tag:blogger.com,1999:blog-77817001100419040992024-03-13T20:26:37.824-07:00Clinical Cases | VignettesMedical Scenarios|Cases|VignettesAnonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comBlogger31125tag:blogger.com,1999:blog-7781700110041904099.post-31542601156953863942013-01-25T00:56:00.001-08:002013-01-25T00:56:17.598-08:00HIV Patient With Confusion and Disorientation<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-family: 'Courier New', Courier, monospace;"><b style="text-decoration: underline;">Clinical Vignette:</b> </span><span style="font-family: Courier New, Courier, monospace;">A 42-year-old HIV-seropositive man presents to Casualty with a two-week history global headache. His partner</span><br />
<span style="font-family: Courier New, Courier, monospace;">says that he has become increasingly confused and disorientated. The patient's latest CD4 count, taken three </span><span style="font-family: 'Courier New', Courier, monospace;">weeks ago, was 50 cells/mm3. He had chosen not to take antiretroviral therapy, but was taking co-trimoxazole as </span><span style="font-family: 'Courier New', Courier, monospace;">prophylaxis against Pneumocystis carinii pneumonia.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">On examination he had mild weakness of his left arm and </span><span style="font-family: 'Courier New', Courier, monospace;">leg in all muscle groups and a right homonymous hemianopia. Fundoscopy was normal with no evidence of </span><span style="font-family: 'Courier New', Courier, monospace;">papilloedema.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">A CT scan of his brain showed several areas of low attenuation in both cerebral hemispheres, but </span><span style="font-family: 'Courier New', Courier, monospace;">there was no enhancement with contrast and no mass effect. What is the most likely diagnosis?</span><br />
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<br />
<ol style="text-align: left;">
<li><span style="font-family: 'Courier New', Courier, monospace;">Cerebral lymphoma</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace;">Cerebral toxoplasmosis</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace;">HIV encephalopathy</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace;">Neurosyphilis</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace;">Progressive multifocal leukoencephalopathy</span></li>
</ol>
<a name='more'></a><br />
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<span style="font-family: Courier New, Courier, monospace; font-size: small;"><u><b>Answer to clinical vignette|case:</b></u> (5)</span><br />
<span style="font-family: Courier New, Courier, monospace; font-size: small;"><br /></span>
<div style="font-family: 'Courier New', Courier, monospace;">
</div>
<br />
<span style="font-family: Courier New, Courier, monospace;">The most likely diagnosis is Progressive multifocal leukoencephalopathy (PML), a demyelinating disease</span><br />
<span style="font-family: Courier New, Courier, monospace;">seen in advanced HIV/AIDS and caused by the JC virus.</span><br />
<span style="font-family: Courier New, Courier, monospace;">Cerebral lymphoma and cerebral toxoplasmosis are often </span><span style="font-family: 'Courier New', Courier, monospace;">associated with mass effect on CT brain scanning. In CNS lymphoma there is usually a solitary lesion. Cerebral </span><span style="font-family: 'Courier New', Courier, monospace;">toxoplasmosis is frequently associated with multiple lesions that show ring enhancement with iv contrast.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">HIV </span><span style="font-family: 'Courier New', Courier, monospace;">encephalopathy may be associated with confusion, but is not associated with this CT appearance.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">This is not a typical </span><span style="font-family: 'Courier New', Courier, monospace;">presentation of neurosyphilis in any of its forms.</span><br />
</div>
Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-60768271839888882782013-01-24T13:49:00.002-08:002013-01-24T13:51:01.042-08:00Female with papules and vesicles<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-family: Courier New, Courier, monospace;"><b style="text-decoration: underline;">Clinical Vignette:</b> <span style="font-size: 12pt;">A 40-year-old female presents with a
six month history of pruritic papules, vesicles and excoriations on the elbows,
knees, buttocks and scalp. Her GP has prescribed topical betamethasone therapy
which has been unhelpful. What is the most likely diagnosis? <o:p></o:p></span></span></div>
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<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;"><br /></span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
</div>
<ol style="text-align: left;">
<li><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Atopic dermatitis (Eczema)</span></span></li>
<li><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Dermatitis herpetiformis</span></span></li>
<li><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Hennoch-Schonlein purpura</span></span></li>
<li><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Psoriasis</span></span></li>
<li><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Scabies</span></span></li>
</ol>
<a name='more'></a><span style="font-family: Courier New, Courier, monospace; font-size: small;"><u><b>Answer to clinical vignette|case:</b></u> (2)</span><br />
<span style="font-family: Courier New, Courier, monospace; font-size: small;"><br /></span>
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</div>
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">The question describes the
characteristic distribution of the lesions of dermatitis herpetiformis. DH is
one of the immunobullous conditions and characteristically has very intensely
pruritic vesicles. It is not usually responsive to topical steroids, but would
respond well to dapsone. It is associated with gluten sensitivity and coeliac
disease.</span></span><br />
<div>
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Atopic eczema is non vesicular and would respond to potent topical
steroids.</span></span></div>
<div>
<span style="font-family: 'Courier New', Courier, monospace; font-size: 16px;">Hennoch-Schonlein purpura </span><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">is a purpuric rash and is non pruritic.</span></span></div>
<div>
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Scabies usually affect
the extremities and rarely affects above the neck line. It does not cause
papules and vesicles.</span></span></div>
</div>
Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-48180348170959565332013-01-24T13:38:00.002-08:002013-01-24T13:40:26.566-08:00Diabetic male with Erectile dysfunction and decreased libido<div dir="ltr" style="text-align: left;" trbidi="on">
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<u style="font-family: 'Courier New', Courier, monospace;"><b>Clinical Vignette:</b></u><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;"> A 36-year-old male with
insulin-dependent diabetes mellitus of three years duration presented with
decreased libido and erectile dysfunction since diagnosis. No abnormalities
were noted on genital examination. Investigations revealed:<o:p></o:p></span></span></div>
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<br /></div>
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<ul style="text-align: left;">
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">plasma testosterone 6.0 nmol/L (9 -
35)</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">plasma follicle stimulating hormone
1.0 u/L (1-8)</span></li>
</ul>
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<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Which of the following investigations
is most appropriate next step?<o:p></o:p></span></span></div>
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</div>
<ol style="text-align: left;">
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">autonomic function testing</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Doppler studies of penile
artery</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Nerve conduction studies</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Serum ferritin</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Serum prolactin</span></li>
</ol>
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"></span><br />
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<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"></span></span></div>
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">
</span>
<a name='more'></a><u style="font-family: 'Times New Roman'; font-size: medium;"><b><br /></b></u><br />
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<span style="font-family: Courier New, Courier, monospace;"><u style="font-size: medium;"><b>Answer to clinical vignette|case:</b></u><span style="font-size: small;"> (4)</span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Times New Roman'; font-size: small;"><br /></span></div>
<span style="font-family: Courier New, Courier, monospace;">This IDDM patient appears to have
hypogonadotrophic hypogonadism (HH) as reflected by low testosterone and low
FSH. The combination is compatible with a diagnosis of haemochromatosis and measuring
ferritin would be a reasonable investigation.</span><br />
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"> Haemochromatosis typically causes
hypogonadotrophic hypogonadism as a consequence of the ferritin deposition
within the pituitary rather than primary testicular dysfunction.</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"> Autonomic
nerve dysfunction is one of the commoner causes of impotence in a diabetic but
in this case is not the cause of his HH. For similar reasons, both nerve
conduction studies and dopplers are irrelevant.</span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"> Prolactin would be a sensible
measurement but probably if you were looking to confirm a diagnosis that
incorporates the diabetes as well, Ferritin would be the investigation of
choice. </span></div>
</div>
Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-87736254222566694972013-01-24T13:27:00.003-08:002013-01-24T13:30:05.196-08:00Female With Acutely Painful Goiter<div dir="ltr" style="text-align: left;" trbidi="on">
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<u style="font-family: 'Courier New', Courier, monospace;"><b>Clinical Vignette:</b></u><span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;"> A 40-year-old female with no
prior history of thyroid disease, presents with a 5 day history of an acutely
painful, left-sided goitre. Clinically she appeared euthyroid, and was
apyrexial.</span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Investigations revealed the following:</span></div>
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<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
</div>
<ul style="text-align: left;">
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Haemoglobin 13.0 g/dL</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">White cell count 7.0 x 109/l</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Platelets count 200,000/mm3</span></li>
</ul>
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">What is the most likely diagnosis?</span><br />
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
</div>
<ol style="text-align: left;">
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">De Quervain's thyroiditis</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Haemorrhage into a cyst</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Hashimoto's thyroiditis</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Staphylococcal abscess</span></li>
<li><span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;">Thyroid carcinoma</span></li>
</ol>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: 'Courier New', Courier, monospace; font-size: 12pt;"></span></div>
<a name='more'></a><br />
<u><b>Answer to clinical vignette|case:</b></u> (2)<br />
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">The left side of this patient's
goitre becomes acutely swollen with no other signs and FBC is normal which
suggests acute haemorrhage into a cyst.</span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">Thyroid cancer is usually painless.</span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-size: 12pt;"><span style="font-family: Courier New, Courier, monospace;">De
Quervain's thyroiditis is a diffusely tender goitre typically with systemic
features such as weight loss, pyrexia and a raised ESR. </span><span style="font-family: Tahoma, sans-serif;"><o:p></o:p></span></span></div>
</div>
Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-23994216720927928332010-12-25T22:48:00.000-08:002010-12-25T22:48:28.521-08:00Clinical Vignette: Young Married Woman With Amenorrhea and Jaundice<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><u><b>Clinical Vignette:</b></u> A 27-year-old married woman with amenorrhoea of 7 months duration is found to have mild jaundice, hepatosplenomegaly, lymphadenopathy and palmar erythema.<br />
Investigations show:</span></div><ul><li><span style="font-size: small;"> Hb 10.4 g/dL</span></li>
<li><span style="font-size: small;"> WBC 2.8 × 109/L</span></li>
<li><span style="font-size: small;"> Platelets 72 × 109/L</span></li>
<li><span style="font-size: small;"> ESR 29 mm in first hour</span></li>
<li><span style="font-size: small;"> Plasma bilirubin 58 μmol/L</span></li>
<li><span style="font-size: small;"> Plasma AST 190 IU/L (normal range 5–35)</span></li>
<li><span style="font-size: small;"> Plasma ALT 105 IU/L (normal range 2–17)</span></li>
<li><span style="font-size: small;"> Plasma alkaline phosphatase 65 IU/L (normal range 30–100)</span></li>
<li><span style="font-size: small;"> Serum albumin 35 g/L</span></li>
<li><span style="font-size: small;"> Serum globulin 68 g/L</span></li>
<li><span style="font-size: small;"> Hepatitis B surface antigen negative</span></li>
<li><span style="font-size: small;"> Antinuclear factor positive at titre of 1/512</span></li>
<li><span style="font-size: small;"> Anti-smooth muscle antibodies positive</span></li>
<li><span style="font-size: small;"> Anti-mitochondrial antibodies positive at titre of 1/64</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;">1 What is the diagnosis?<br />
<b>(a)</b> Primary biliary cirrhosis<br />
<b>(b)</b> Chronic active hepatitis<br />
<b>(c)</b> Wilson’s disease<br />
<b>(d)</b> Hepatitis C infection<br />
<b>(e)</b> Drug toxicity</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"></span></div><a name='more'></a><span style="font-size: small;"><u><b>Answer to clinical vignette | case:</b></u> <span style="font-size: large;"><u>(b)</u></span></span><br />
<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
The diagnosis is based on the differential of jaundice associated with elevated transaminases (transaminitis) rather than an obstructive picture. In the presence of autoimmune serology, an<br />
autoimmune disease is the most likely cause.</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Courier New",Courier,monospace;"><u><span style="font-size: small;"><b>Causes Of Hepatocellular Jaundice:</b></span></u></div><div style="font-family: "Courier New",Courier,monospace;"><br />
</div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>Infections</b><br />
<b>– Viral</b></span></div><ul><li><span style="font-size: small;"> Hepatitis A, B, C, D, E</span></li>
<li><span style="font-size: small;"> EBV</span></li>
<li><span style="font-size: small;"> CMV</span></li>
<li><span style="font-size: small;"> HIV</span></li>
<li><span style="font-size: small;"> Arboviruses</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>– Spirochaetes</b></span></div><ul><li><span style="font-size: small;"> Leptospira</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>– Protozoa</b></span></div><ul><li><span style="font-size: small;"> Toxoplasma</span></li>
<li><span style="font-size: small;"> Amoeba</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><b><span style="font-size: small;">- Toxins</span></b></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>- Drugs</b></span></div><ul><li><span style="font-size: small;"> Nitrofurantoin</span></li>
<li><span style="font-size: small;"> Halothane</span></li>
<li><span style="font-size: small;"> Isoniazid</span></li>
<li><span style="font-size: small;"> Many others</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>- Inherited disorders</b></span></div><ul><li><span style="font-size: small;"> Wilson’s disease</span></li>
<li><span style="font-size: small;"> Galactosaemia</span></li>
</ul><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>- Autoimmune disease/connective tissue disorders</b></span></div><ul><li><span style="font-size: small;"> Chronic active hepatitis</span></li>
<li><span style="font-size: small;"> SLE</span></li>
<li><span style="font-size: small;"> Scleroderma</span></li>
</ul>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-80549969329877658582010-12-23T22:34:00.000-08:002010-12-23T22:34:23.114-08:00Clinical Case: Newborn With Severe Acidosis, Vomiting, Hypotonia, and Neurologic Deficits<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A newborn presents with severe acidosis, vomiting, hypotonia, and neurologic deficits. Serum analysis </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">reveals </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">elevated levels of lactate and alanine. These observations suggest a deficiency in which of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">following </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">enzymes? </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Alanine aminotransferase </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. Glutamate dehydrogenase </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Lactate dehydrogenase </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Pyruvate carboxylase </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Pyruvate dehydrogenase </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Explanation: </b></span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is E.</b> A common Biochem clinical vignette. Pyruvate dehydrogenase (PDH) catalyzes the irreversible conversion of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">pyruvate to </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">acetyl-CoA. If PDH is absent, pyruvate will be used in other pathways instead. Pyruvate will be </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">converted to </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">alanine via alanine aminotransferase (choice A) and to lactate via lactate dehydrogenase (choice C). </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Glutamate dehydrogenase (choice B) is involved in oxidative deamination, releasing ammonium ion </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">for urea </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">synthesis. Deficiency of this enzyme would not cause the symptoms described. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Pyruvate carboxylase (choice D) is a gluconeogenic enzyme that catalyzes the conversion of pyruvate </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">to </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">oxaloacetate. Deficiency of this enzyme would not cause the symptoms described.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-11752593305371202832010-12-23T22:27:00.000-08:002010-12-23T22:27:28.566-08:00Clinical Case: Trisomy 21 Complications<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 42-year-old woman is pregnant and undergoes amniocentesis. The results of the amniocentesis </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are consistent with trisomy 21, but the woman wishes to carry the pregnancy to term. After </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">birth, this child will be at increased risk for the development of which of the following </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">neoplasms? </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Acute lymphoblastic leukemia </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>B</b>. Basal cell carcinoma </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>C</b>. Colon cancer </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>D</b>. Glioblastoma multiforme </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>E</b>. Hodgkin's disease </span><br />
<br />
<a name='more'></a><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Explanation: </b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><br />
</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>The correct answer is A. </b>This clinical vignette mentions another common USMLE question. In addition to the well-known mental retardation associated with Down's </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">syndrome (trisomy 21), affected individuals have an increased incidence of a variety of medical </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">problems. Acute myeloblastic leukemia is seen in newborns and acute lymphoblastic leukemia is </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">seen in older children. Epilepsy, which can be very difficult to manage, affects up to 10% of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">children with Down's. On occasion, the malformed head and neck region can undergo atlantoaxial </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dislocation, causing a sudden or progressive quadriparesis. Congenital malformations of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">cardiac system are common (40% of cases), and include (in decreasing order of frequency) atrial </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">and ventricular septal defects, tetralogy of Fallot, and patent ductus arteriosus. The </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">development of the hypopharynx is often poor, predisposing to both aspiration pneumonia and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">obstruction by enlarged adenoids. Other malformations that occur with lower frequency include </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">duodenal atresia and imperforate anus. Acquired autoimmune hypothyroidism is frequent. Boys are </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infertile; girls are subfertile but can get pregnant. Alzheimer-like changes develop in mid-</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">adulthood. Visual problems related to strabismus, nystagmus, or myopia are common. None of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">other neoplasms occur with increased frequency in individuals with trisomy 21.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-1656331147319129882010-12-23T22:22:00.000-08:002010-12-23T22:22:39.145-08:00Clinical Case: Number Of Nucleotides....<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> Transcription of a prokaryotic gene by RNA polymerase yields an mRNA corresponding to a single p</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">olypeptide chain containing 64 amino acids. The mRNA has a 5' untranslated region of 120 </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">nucleotides and a 3' untranslated region of 240 nucleotides. Approximately how many nucleotides </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are in the coding region of the mRNA? </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. 64 </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>B</b>. 128 </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>C</b>. 192 </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>D</b>. 424 </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>E</b>. 552 </span><br />
<br />
<a name='more'></a><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Explanation: </b></span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>The correct answer is C.</b> This vignette has distractors, so beware. Regardless of how long the untranslated regions are, the number of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">nucleotides in the coding region of an mRNA is three times the number of amino acids, since </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">three nucleotides are required to code for each amino acid, and 3 X 64 = 192. In reality, three </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">nucleotides code for the first amino acid (formyl-methionine in prokaryotes, methionine in </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">eukaryotes), which may be removed in posttranslational steps, and three nucleotides at the 3' </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">end (are needed to terminate the process (i.e., a STOP codon), so the actual number would likely </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">be slightly higher.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-43968692500149582602010-12-23T22:16:00.000-08:002010-12-23T22:16:30.423-08:00Clinical Case: A Child With Microcephaly, Cat-Like Cry.....<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 6-month-old child with severe mental retardation is brought to a specialty clinic. Physical </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">examination is remarkable for microcephaly, a cat-like cry, and an anti-mongoloid slant to the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">palpebral fissures. This child should be further evaluated for which of the following disorders?</span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Duodenal atresia </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>B</b>. Hepatocellular carcinoma </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>C</b>. Nephroblastoma </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Renal cysts </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>E</b>. Ventricular septal defect </span><br />
<br />
<a name='more'></a><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Explanation: </b></span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>The correct answer is E.</b> This clinical vignette describes a common USMLE scenario, in which the diagnosis is not asked but something related to that diagnosis is asked. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The presentation is classic for cri-du-chat syndrome, caused by a </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">deletion of the short arm of chromosome 5(5p-). Approximately one-quarter of such patients have </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">a ventricular septal defect. Other features of the syndrome include short stature, distorted </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">laryngeal anatomy, profound mental retardation, microcephaly, a wide nasal bridge, and an anti-</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">mongoloid slant to the palpebral fissures. The laryngeal malformation causes feeding and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">respiratory difficulties, as well as the cat-like cry, which typically disappears by age 1. Many </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">patients survive to adulthood, but are usually institutionalized.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-69415769213123537902010-12-23T07:19:00.000-08:002010-12-23T07:19:18.208-08:00Clinical case: A young woman with recurrent episodes of diarrhea, crampy abdominal pain, and slight fever over the last 2 years....<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b style="text-decoration: underline;">Clinical Vignette:</b> A 22-year-old woman has had recurrent episodes of diarrhea, crampy abdom</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">inal pain, and slight fever over the last 2 years. At first the episodes, which usu</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ally last 1 or 2 weeks, were several months apart, but recently they have </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">occurred more frequently. Other symptoms have included mild joint pain and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sometimes red skin lesions. On at least one occasion, her stool has been </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">guaiac-positive, indicating the presence of occult blood. Colonoscopy reveals </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">several sharply delineated areas with thickening of the bowel wall and mucosal </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ulceration. Areas adjacent to these lesions appear normal. Biopsies of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">affected areas show full-thickness inflammation of the bowel wall and several </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">noncaseating granulomas.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ What is the most likely diagnosis?</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ What are the common complications of this disease?</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<blockquote>Summary: A 22-year-old woman has a 2-year history of recurrent diarrhea, abdominal pain, slight fever, joint pain, and red skin lesions. Colonoscopy reveals several sharply delineated areas with thickening of the bowel wall and mucosal ulceration, which on biopsy show full-thickness inflammation of the bowel wall and several noncaseating granulomas.</blockquote><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ <b>Most likely diagnosis:</b> Crohn disease</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ <b>Common complications of this disease</b>: Malabsorption and </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">malnutrition, fibrous strictures of the intestine, and fistulae to other </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">organs, such as from bowel to skin or bowel to bladder</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>CLINICAL CORRELATION</u></b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">This clinical vignette test a very common question asked on the USMLE step 1.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The patient’s presentation is very characteristic for inflammatory bowel dis</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ease, that is, a several-year history of diarrhea and abdominal pain.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Additionally, the colonoscopy revealing full-thickness inflammation with non-</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">caseating granulomas is consistent with Crohn disease. Crohn disease is a </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">chronic inflammatory condition that is ubiquitous in its distribution in the gas</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">trointestinal tract. It most commonly manifests in the small intestine, in par</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ticular the terminal ileum. The disease exhibits aggressive activity of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">gastrointestinal immune system, but the exact cause is unknown. Published </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">studies in the United States report incidence rates that vary between 1.2 and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">8.8 per 100,000 population; the prevalence is 44 to 106 per 100,000. The con</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dition is more common in the cold climates of the northeastern United States </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">than in the south. Those of Jewish ethnicity have a high incidence. The disor</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">der, which is slightly more common in females, has a bimodal age distribution, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">peaking in the early twenties and again emerging in the mid-sixties. Theories </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">regarding pathogenesis have referred to genetics, infection, autoimmune or </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">allergic processes, thromboembolic disorders, and dietary disorders.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-46206052545884369422010-12-22T06:49:00.000-08:002010-12-23T07:24:35.996-08:00Clinical Case: Woman With Fevers and Fatigue ........<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><u style="font-weight: bold;">Clinical Vignette:</u> A 32-year-old African American woman complains of mild fevers and fatigue for the past month. She has no significant past medical history. Her temperature is 38.I C (100.6 F), blood pressure is 115/70 mm Hg, pulse is 75/min, and respirations are 18/min. Nontender, mobile, cervical and axillary lymph nodes are noted. Auscultation of the lungs reveals fine crackles bilaterally. A chest x-ray film shows hilar lymphadenopathy and diffuse interstitial infiltrates. Lymph node biopsy shows noncaseating granulomas. Which of the following is the most appropriate therapy?</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(A)</b> Allopurinol</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(B)</b> Angiotensin converting enzyme (ACE) inhibitor</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(C)</b> Cyclosporine</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(D)</b> Gluoocorliooids</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(E)</b> Isoniazid</span><br />
<br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>The correct answer is D</b>. This clinical vignette will be asked on the USMLE one way or the other... </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">This patient has pulmonary </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sarcoidosis. The peak age group for sarcoidosis is 20-40 </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">years, and the disease seems to be more common in </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">blacks. Noncaseating granulomas can occur in the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">lungs, heart, kidneys, skin, liver, or other organs. Most </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">characteristically, the patients are asymptomatic, and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">the disease is detected by an abnormal chest x-ray film. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">which usually shows bilateral symmetric hilar adenopa</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">thy often associated with paratracheal adenopathy </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">and/or parenchymal infiltrates. Patients may have </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">uveitis, peripheral arthritis, skin involvement with </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">granulomas, or erythema nodosum. The lungs are the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">most frequently involved organs; pulmonary symptoms, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">when present, include dyspnea on exertion, nonpro</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ductive cough, and wheezing. Radiologic abnormalities </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are graded 0-3. Grade 0 is associated with a normal x-</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ray. Grade I is associated with lymph node enlargement </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">without pulmonary parenchymal abnormalities. Grade </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">2A is a combination of lymph node and diffuse pul</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">monary parenchymal disease. Grade 2B is a diffuse </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">parenchymal disease without lymph node enlargement,</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Grade 3 is associated with radiographic changes indi</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">cating more chronic disease with pulmonary fibrosis </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(“honey-combing”). Many patients show spontaneous </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">total remission of disease for a period up to 3 years.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Prednisone is usually the drug of choice for treatment, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">with a starting dose of 30-40 mg/day. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Neither allopurinol (choice A) nor cyclosporine </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(choice C), an immune modulator, has been proven to</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">be of benefit in sarcoidosis.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Levels of ACE may be elevated in patients with sarcoidosis but are also elevated in many other diseases. This enzyme elevation is thought to be related to induction by the granulomas. There is no evidence that ACE inhibitors (choice B) have any therapeutic value in treatment of sarcoidosis.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">At one point in history, some theorized that sarcoidosis was caused by a type of mycobacterium, related to tuberculosis. However, this has not been definitively proven. Furthermore, isoniazid (choice E) has not been shown to be beneficial.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-12670402532292049142010-12-22T06:07:00.000-08:002010-12-23T07:25:51.006-08:00Clinical Case: A Young Obese Woman With Irregular Menses Presents With Acne And Hirsutism<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 20-year-old Caucasian woman was referred with persistent severe acne and hirsutism. Her menses were </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infrequent, irregular and heavy. She was on no medication and used barrier methods of contraception. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Her mother also had irregular menses. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">On examination, she was obese, had moderately severe acne, greasy skin, and excessive amounts of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">body hair in a male pattern distribution. The distribution of her obesity was uniform. Her visual fields </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">were normal. There were no other abnormalities on examination or urinalysis.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Results of investigations were as follows:</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Plasma luteinizing hormone 20 IU/L (normal range 3–8)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Plasma follicle stimulating hormone 6 IU/L (normal range 2–8)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Plasma prolactin 423 IU/L (normal range <600)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Plasma thyroxine 98 nmol/L (normal range 70–140)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Plasma testosterone 11 nmol/L (normal range 1–3)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Dehydroepiandrosterone sulphate(DHAS) 6 μmol/L (normal range 3–7)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Urinary 17-oxosteroids 39 μmol/L (normal range 14–59)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>1</u></b> <b>What is the diagnosis?</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(a)</b> Congenital adrenal hyperplasia</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(b)</b> Anabolic steroids</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(c)</b> Pituitary adenoma</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(d)</b> Polycystic ovary syndrome</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>(e)</b> Cushing’s syndrome</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>2</u></b> <b>How would you confirm this?</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(a) MRI pituitary</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(b) 24-hour urinary cortisol</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(c) Pelvic ultrasound scan</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(d) CT abdomen and pelvis</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(e) LH suppression test</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Answers:</u></b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u></u>1 (d)</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>2 (c)</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Essence</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A young obese woman with irregular menses presents with acne and hirsutism. There is a family history of this problem and she has raised LH and testosterone.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Differential diagnosis</u></b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Another USMLE and MRCP favourite clinical vignette...</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">If hirsutism is not associated with menstrual irregularities you are unlikely to find an underlying cause. This woman does have menstrual irregularity. However, there are specific reasons to exclude most of the differential diagnoses. Her corticosteroid production is normal (DHAS and 17-oxysteroids) which make adrenal causes unlikely.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Similarly, there are no other clinical features of pituitary disease, making acromegaly unlikely, Cushing’s is excluded by the clinical clue of the uniform distribution of the obesity, and the thyroxine level is normal. She is on no medication and there are no features of systemic disease.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The cause is likely to be ovarian. A malignant disease is very rare and unlikely, whereas polycystic ovary syndrome (Stein–Leventhal syndrome) is common – it is the cause of 80 per cent of all cases of oligomenorrhoea and 25 per cent cases of amenorrhoea. It is classically associated with greasy skin and acne as well as obesity and a family history is common. Levels of LH are raised, FSH normal or low, and testosterone/DHAD at the upper limit of normal or raised. It can be confirmed with a pelvic ultrasound scan; a CT is unnecessary and has a high radiation dose.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Excess androgens cause the hirsutism and masculinization and excess oestrogens inhibit FSH and stimulate LH, leading to failure of ovulation.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-78450907340635166312010-12-22T05:55:00.000-08:002010-12-23T07:27:22.066-08:00Clinical Case: A Child With Swollen Left Knee<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 6-year-old boy was referred with swelling of his left knee. He had played football in his school </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">playground 48 hours before and had not noticed any problems until the morning of referral. He had had </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">no other problems. There was no family or personal history of significance. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">On examination, an otherwise well-looking boy had a red swollen knee which was warm and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">moderately painful to move. He was not systemically unwell and had a pyrexia of 37.3°C. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Results of investigations were as follows:</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Hb 11.8 g/dL</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">WBC 6.9 × 109</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">/L</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Platelets 405 × 109</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">/L</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Bleeding time normal</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Prothrombin time 13 s (normal range 11–15)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Activated partial thromboplastin time 60 s (control 25–34)</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Factor VIII level 123 per cent</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">What is the diagnosis?</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>(a)</b> Von Willebrand’s disease</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>(b)</b> Factor VIII deficiency</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>(c)</b> Factor V (Leiden) mutation</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>(d)</b> Factor IX deficiency</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>(e)</b> Protein C deficiency</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Answer: (d)</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><br />
</b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Essence</u></b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A 6-year-old boy presents with a painful, red,</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">swollen knee. There is no evidence of systemic </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infection but he has a prolonged APTT with </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">normal factor VIII levels</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Differential diagnosis</u></b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Well I cant stress it more but know these disease in the clinical vignette for your USMLE.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The clinical history suggests a differential diagno</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sis of haemarthrosis or septic arthritis. However,</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">the prolonged APTT make this a haemarthrosis.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The normal bleeding time and platelet level make </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">this a defect of the clotting cascade, and the APTT </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">and prothrombin time put it in the intrinsic </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">pathway. The most common defect, factor VIII </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">deficiency or haemophilia A, is excluded; the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">answer is the next most likely, factor IX deficiency </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">or haemophilia B. The lack of a family history is </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">of no significance as one-third of patients carry </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">new mutations.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-34574796706688809922010-12-21T08:42:00.000-08:002010-12-23T07:29:15.527-08:00USMLE Genetics Question<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> NlaIII is a restriction enzyme recognizing the short palindrome GTAC, which is not present in the normal exon 9. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The researcher digests the amplified exon 9 with this enzyme, then subjects it to Southern blotting with a probe </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">directed against the entire amplified region. Which of the following banding patterns would most likely be found in </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">an individual heterozygous for the mutation described? </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. One thick band of 222 bp </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. Three bands of 180, 32 and 10 bp </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Three bands of 222, 126 and 96 bp </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Two thick bands of 126 and 96 bp </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Two bands of 444 and 222 bp </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Explanation: </b></span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is C.</b> You will surely get questions like these in your USMLE. The point mutation has resulted in the introduction of the palindrome recognized by </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">NlaIII, GTAC. Enzymatic digestion of the amplified 222 bp mutated exon 9 should therefore result in two </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">fragments, of combined mass 222. Digestion of the normal 222 bp amplified exon should not result in </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">fragmentation, and it should remain a 222 bp fragment. A heterozygote individual has one normal allele of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">LDL receptor gene and one mutated allele. Digestion of the PCR-amplified exon 9 should therefore result in 3 </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">different restriction fragments: the 222 bp normal allele, and the fragmented mutant allele. Note that 126 and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">96 add up to 222. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> One thick band at 222 (choice A) would be expected in an homozygous normal individual, both alleles </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">remaining intact after NlaIII digestion. The thickness of the band only shows the abundance of the restriction </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">fragment of that size. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Three bands of 180, 32 and 10 bp (choice B) would indeed indicate digestion by the restriction enzyme. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">However, the lack of 222 bp restriction fragment would rule out the presence of a normal allele. Also note that </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">since the sum of the three fragments is 222, it would indicate the presence of 2 restriction sites for the enzyme, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">which is not compatible with the information given. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Two bands of 126 and 96 bp (choice D) would be the pattern expected from a homozygous individual for the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">mutated allele. The thickness of the band reflects the abundance of restriction fragment of that size. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Two bands of 444 and 222 bp (choice E) would be very difficult to interpret. A fragment that is larger than the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">original amplified material could not be created by enzyme digestion.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-19023248200497626472010-12-20T09:19:00.000-08:002010-12-23T07:30:45.811-08:00Clinical Case: Man With Progressive Low Back Pain And Weakness With Episode Of Loin Pain<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b><u>Clinical Vignette:</u></b> A 24-year-old man with progressive low back pain and weakness finally sees his doctor on account of an episode of left loin pain. Investigations show haematuria and a urinary pH of 7.<br />
Other investigations show:</span><br />
<ul><li><span style="font-size: small;"> Plasma sodium 135 mmol/L</span></li>
<li><span style="font-size: small;"> Plasma potassium 2.8 mmol/L</span></li>
<li><span style="font-size: small;"> Plasma urea 5.7 mmol/L</span></li>
<li><span style="font-size: small;"> Plasma creatinine 107 μmol/L</span></li>
<li><span style="font-size: small;"> Plasma chloride 115 mmol/L</span></li>
<li><span style="font-size: small;"> Plasma bicarbonate 16 mmol/L</span></li>
</ul><span style="font-size: small;"> </span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><u><b>1</b></u> What is the diagnosis?</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
(a) Type I (distal) renal tubular acidosis<br />
(b) Type II (proximal) renal tubular acidosis<br />
(c) Type IV renal tubular acidosis<br />
(d) Bartter’s syndrome<br />
(e) Gittleman’s syndrome</span></div><span style="font-family: 'Courier New', Courier, monospace; font-size: small;"></span><br />
<a name='more'></a><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><u><b>2</b></u> Suggest two abnormalities which might be seen on a plain radiology:</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><br />
(a) Small renal outlines<br />
(b) Horseshoe kidney<br />
(c) Renal calculi<br />
(d) Sloughed renal medullary papillae<br />
(e) Brown tumours<br />
(f) Greenstick fractures<br />
(g) Looser’s zones<br />
(h) Subchondral erosions<br />
(i) Osteitis fibrosa et cystica<br />
(j) Erosion of subendostial bone on ulnar aspect of hand bones</span><br />
<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;">Answers:</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>1 (a)<br />
2 (c), (g)</b></span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b> </b><br />
<u><b>Explanation</b></u></span><br />
<span style="font-size: small;">Grasp the concept in this clinical vignette for both USMLE and MRCP.<br />
In renal tubular acidosis (RTA) there is a failure to acidify urine to a level appropriate for blood pH; systemic acidosis is therefore not corrected. Unlike renal failure, anions such as sulphate and phosphate are filtered normally and are therefore unavailable to balance the loss of bicarbonate; electrical neutrality is instead maintained by renal chloride absorption, resulting in a hyperchloraemic metabolic acidosis with a normal anion gap.</span><br />
<span style="font-size: small;"> </span><span style="font-size: small;">In proximal (type II) RTA, there is a diminished renal bicarbonate threshold because bicarbonate reabsorption in the proximal tubules is incomplete. The increased urinary bicarbonate excretion lowers the plasma bicarbonate concentration until a new<br />
steady state is reached. At this stage the urine is free of bicarbonate and has an acid pH to match the systemic acidosis. Proximal RTA in its primary form usually presents in infants with failure to thrive, polyuria and growth retardation. Secondary forms may occur in patients with generalized proximal tubular damage due to cystinosis, Wilson’s disease or myeloma, and after renal transplantation. There is no metabolic bone disease and nephrocalcinosis is unusual.</span><span style="font-size: small;"> </span><span style="font-size: small;">The pathophysiology of distal (type I) RTA is complex, but can be thought of in simple terms as a failure of hydrogen ion secretion in the distal tubules. The urine is therefore never acid, even in the presence of systemic acidosis.</span><span style="font-size: small;"> </span><span style="font-size: small;">The systemic acidosis reduces tubular reabsorption of calcium, resulting in hypercalciuria and secondary hyperparathyroidism: nephrocalcinosis and bone disease are therefore characteristic.</span><span style="font-size: small;">Distal RTA is most commonly a dominantly inherited condition.</span><span style="font-size: small;"> </span><span style="font-size: small;">In both disorders acidosis provokes potassium loss and hypokalaemia, and patients often complain of weakness as a result.</span><span style="font-size: small;"> </span><span style="font-size: small;">The diagnosis of distal RTA can be made in a patient with a hyperchloraemic metabolic acidosis and a urinary pH above 5.5. If acidosis is mild or absent, an ammonium chloride loading test may be necessary. Normal individuals should lower their urinary pH to below 5.5; patients with distal RTA will not.</span><span style="font-size: small;"> </span><span style="font-size: small;">Proximal tubular acidosis should be considered especially in patients with hyperchloraemic acidosis and associated features such as glycosuria and aminoaciduria. If the metabolic acidosis is severe enough, an early morning urine of pH 5.5 or less supports the diagnosis. If a low urinary pH is not found, an ammonium chloride test should be performed to exclude the diagnosis of distal RTA. A definitive diagnosis can be made by bicarbonate titration. The characteristic finding is an elevated urinary excretion of bicarbonate in the face of a normal plasma bicarbonate.</span><span style="font-size: small;"> </span><span style="font-size: small;">This patient has distal RTA as the urine pH is high despite systemic acidosis, and because there is clinical evidence of bone disease and nephrocalcinosis. </span></div>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-45899441251290421192010-12-20T01:03:00.000-08:002010-12-23T07:31:56.642-08:00Clinical Case: Reason For Higher Insulin Levels<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b><u>Clinical Vignette:</u></b> Two normal, healthy subjects volunteer for a study on insulin secretion. In Patient 1, blood glucose is increased to 150 mg/dL by direct intravenous infusion. In Patient 2, blood glucose is increased to 150 mg/dL by ingestion of oral glucose. The peak plasma insulin concentration produced in Patient 1 is 70 µU/mL while in Patient 2, it is 95 µU/mL. Which of the following best explains the higher insulin concentration in Patient 2? <br />
<br />
<b>A</b>. Ingested glucose activates a sympathetic reflex that increases beta cell release of insulin. <br />
<br />
<b>B</b>. Ingested glucose increases duodenal secretion of gastric inhibitory peptide (GIP), increasing beta cell release of insulin. <br />
<br />
<b>C</b>. Intravenous glucose increases islet cell secretion of somatostatin, inhibiting beta cell release of insulin. <br />
<br />
<b>D</b>. Intravenous glucose increases islet cell secretion of glucagon, inhibiting beta cell release of insulin. </span></div><a name='more'></a><br />
<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;">Explanation: <br />
<br />
<b>The correct answer is B.</b> Learn it and understand for your USMLE. Ingestion of glucose results in secretion of a "gut factor" into the blood that subsequently increases insulin secretion by &beta; cells. The most likely candidate for this action is the intestinal peptide known as gastric inhibitory peptide (GIP), which obviously was named for its effects on the stomach. GIP secretion is increased during ingestion of glucose and the blood level produced is sufficient to stimulate insulin secretion. Because of this effect on insulin secretion, GIP is sometimes referred to as glucose-dependent insulinotropic peptide. <br />
<br />
Activation of the sympathetic innervation to the pancreas inhibits insulin secretion via an &alpha;2-adrenergic mechanism. Hence, any sympathetic reflexes activated during ingestion of glucose would decrease (not increase, choice A) insulin secretion. <br />
<br />
While paracrine release of somatostatin (choice C) by Delta; cells in the islets does inhibit insulin secretion by beta; cells, there is no reason to suspect that intravenous versus ingested glucose would have a differential effect on somatostatin release. The same holds true for glucagon secretion by &alpha; cells. Furthermore, glucagon has a paracrine effect to increase (not decrease, choice D) insulin secretion.</span></div>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-5203406506825738742010-12-17T08:26:00.000-08:002010-12-23T07:33:38.174-08:00Clinical Case: Patient With Elevated Serum Cortisol level Not Suppressed With Dexamethasone<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b><u>Clinical Vignette:</u></b> A 57-year-old man complains of fatigue, weakness, and weight gain, particularly around the abdomen. On examination, he is found to have hypertension, fullness over the upper back, and abdominal striae. Laboratory studies include an elevated serum cortisol level that is not suppressed with dexamethasone. Imaging studies reveal no pituitary or adrenal masses, but a computed tomography (CT) scan of the chest shows a right lung mass arising near the hilum. <br />
<br />
◆ What is the most likely diagnosis? <br />
◆ What other disorders may cause similar clinical findings? <br />
◆ What are the underlying mechanisms involved? </span></div><div style="font-family: "Courier New",Courier,monospace;"><br />
</div><div style="font-family: "Courier New",Courier,monospace;"></div><a name='more'></a><br />
<div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
</span></div><blockquote style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><b>Summary:</b> A 57-year-old man complains of cushingoid features. Laboratory studies include an elevated cortisol level that is not suppressed with dexamethasone. A CT scan of the chest shows a right lung mass arising near the hilum.</span></blockquote><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;">◆ <b><u>Most likely diagnosis:</u></b> Cushing syndrome caused by small cell carcinoma of lung through a paraneoplastic process.</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
◆ <u><b>Other disorders causing similar clinical findings:</b></u> Cancers of various origins; commonly seen in pancreatic cancer, small cell carcinoma of lung, and thymoma.</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
◆ <u><b>Underlying mechanisms:</b></u> The lung cancer cells probably are producing ectopic adrenocorticotropic hormone (ACTH), resulting in Cushing syndrome.</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"><br />
<b>CLINICAL CORRELATION</b></span><br />
<span style="font-size: small;">Another great clinical vignette for USMLE... Grasp the concept in this Clinical Vignette for your USMLE.<br />
The paraneoplastic syndromes are collections of symptoms that result from substances produced by a tumor, and they occur remotely from the tumor. Approximately 10 percent of malignancies manifest these syndromes. Small cell carcinoma is the most common type of cancer that causes clinical hormone syndromes, and it causes a number of paraneoplastic effects. These manifestations can result from immune reactivity to tumor and/or tissue antigens, metabolic disorders causing electrolyte abnormalities, and endocrine dysfunction. The tumor cells may produce ectopic ACTH, resulting in Cushing syndrome. The symptoms of Cushing syndrome are nonspecific and often are attributed to other factors. Another paraneoplastic hormone syndrome that commonly occurs in small cell carcinoma of lung is the syndrome of inappropriate antidiuretic hormone (SIADH), which is caused by the secretion of adrenocorticotropic hormone (ACTH) from the tumor. Symptoms are related to the plasma hypotonicity that is secondary to water retention.</span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"> </span></div><div style="font-family: "Courier New",Courier,monospace;"><span style="font-size: small;"> </span></div><br />
<table border="1" cellpadding="0" cellspacing="0" class="MsoTableGrid" style="border-collapse: collapse; border: none; mso-border-alt: solid windowtext .5pt; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-yfti-tbllook: 1184;"><tbody>
<tr style="mso-yfti-firstrow: yes; mso-yfti-irow: 0;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0in;"><span style="font-size: large;"><b>CLINICAL <o:p></o:p></b></span></div><div class="MsoNormal" style="line-height: normal; margin-bottom: 0in;"><span style="font-size: large;"><b>SYNDROMES</b></span></div></td> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0in;"><span style="font-size: large;"><b>MECHANISM<o:p></o:p></b></span></div><div class="MsoNormal" style="line-height: normal; margin-bottom: 0in;"><span style="font-size: large;"><b>OF ACTION</b></span></div></td> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0in;"><span style="font-size: large;"><b>MAJOR FORMS OF CANCER</b></span></div></td> </tr>
<tr style="mso-yfti-irow: 1;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Cushing syndrome</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Adrenocorticotropic hormone (ACTH) or ACTH-like substance</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Small cell carcinoma of lung, pancreatic<br />
cancer</div></td> </tr>
<tr style="mso-yfti-irow: 2;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Syndrome of inappropriate <o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">ADH secretion</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Antidiuretic hormone (ADH) or<br />
atrial natriuretic hormone</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Small cell carcinoma of lung, <o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">brain tumors</div></td> </tr>
<tr style="mso-yfti-irow: 3;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Hypoglycemia</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Insulin or insulin like <o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">substance</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;"><span class="SpellE">Fibrosarcoma</span>, hepatocellular<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">carcinoma</div></td> </tr>
<tr style="mso-yfti-irow: 4;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;"><span class="SpellE">Hypercalcemia</span></div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Parathyroid<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">hormone-related protein</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Breast cancer, renal<br />
carcinoma,<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">squamous cell carcinoma of the<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">lung</div></td> </tr>
<tr style="mso-yfti-irow: 5;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Carcinoid syndrome</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Serotonin, <span class="SpellE">bradykinin</span></div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Bronchial adenoma, pancreatic<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Carcinoma, gastric carcinoma<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;"><br />
</div></td> </tr>
<tr style="mso-yfti-irow: 6;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Polycythemia</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Erythropoietin</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Renal cell carcinoma,</div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Cerebellar <span class="SpellE">hemangioma</span><o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;"><br />
</div></td> </tr>
<tr style="mso-yfti-irow: 7;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Myasthenia (Eaton-<span class="SpellE">Lamber</span><o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">syndrome)</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Immune-mediated<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">(autoantibodies)</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Bronchogenic carcinoma, <o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">breast cancer<o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;"><br />
</div></td> </tr>
<tr style="mso-yfti-irow: 8; mso-yfti-lastrow: yes;"> <td style="border: 1pt solid windowtext; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Venous thrombosis</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Tumor products that <o:p></o:p></div><div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">induce thrombosis</div></td> <td style="border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color; border-style: none solid solid none; border-width: medium 1pt 1pt medium; font-family: "Courier New",Courier,monospace; padding: 0in 5.4pt; width: 159.6pt;" valign="top" width="213"><br />
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in;">Pancreatic cancer and others</div></td> </tr>
</tbody></table>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-12930949669266951532010-12-17T07:51:00.000-08:002010-12-23T07:35:10.951-08:00Clinical Case: Anticancer Drug Side Effects<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><b><u>Clinical Vignette:</u></b> A 71-year-old man presents with a complaint of dyspnea for the past week. The patient has a history of diabetes and hypertension and was recently diagnosed with cancer. He is currently on multiple drug therapy. On examination, temperature is 37.2 C (99.0 F), his blood pressure is 140/90 mm Hg, pulse is 90/min, and respirations are 22/min. His lungs have a few crackles at the bases with no wheezing. A chest x-ray film shows bilateral diffuse interstitial markings. Which of the following medications is likely responsible for the patient’s dyspnea?</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><br />
<b>A. </b>Bleomycin<br />
<b>B. </b>Cisplatin<br />
<b>C. </b>Mithramyvcin<br />
<b>D. </b>Verapamil<br />
<b>E. </b>Vincristine</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><br />
</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"></span><br />
<a name='more'></a><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"><b> The correct answer is A.</b> Learn about anticancer drugs, high yield stuff for USMLE. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><a href="http://www.amazon.com/Bleomycin-Current-Status-New-Developments/dp/0121615502?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Bleomycin</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=0121615502" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> can cause pneumonitis, which progresses to pulmonary fibrosis. Cough and shortness of breath are indications of the development of this complication. The pulmonary toxicity is usually age- and dose-related, although an allergic form of pneumonitis has been reported.</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"> <a href="http://www.amazon.com/Revivin/dp/B0009SY9R8?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Cisplatin</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B0009SY9R8" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> (chioice B) produces tinnitus, hearing loss,<br />
and nephrotoxicity.</span><br />
<span style="font-family: 'Courier New', Courier, monospace; font-size: small;"> <a href="http://www.amazon.com/Mithramycin-Websters-Timeline-History-1960/dp/B003TXS3LS?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Mithramycin</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B003TXS3LS" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> (choice C) is associated with hemolytic<br />
uremic syndrome, thrombocytopenia, hepatotoxicity and nephrotoxicity.<br />
Calcium-channel blockers, such as <a href="http://www.amazon.com/Verapamil-Lambert-M-Surhone/dp/6131150303?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">verapamil</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=6131150303" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> (choice<br />
D), cause headache, dizziness, and nausea. They may increase the extent of heart block and worsen congestive heart failure.<br />
<a href="http://www.amazon.com/Vincristine-vinblastine-production-Biotechnological-intervention/dp/3843374643?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Vincristine</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=3843374643" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> (choice E) causes neuropathy rather than<br />
pulmonary symptoms.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-91799107327706994622010-12-15T22:46:00.000-08:002013-01-25T02:58:52.453-08:00Clinical Case: Old Man With Colonoscopic Findings Of Small Pedunculated Polyps In The Right Colon<div dir="ltr" style="text-align: left;" trbidi="on">
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 45-year-old man with a family history of colon cancer undergoes a screeni</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ng colonoscopy. No invasive carcinomas are identified, but two small pedun</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">culated tubular adenomas are removed and one villous adenoma measuring </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">5 mm in diameter is biopsied. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ What is the most likely diagnosis? </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ What are the syndromes that could predispose this individual </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ What other dietary factors could play a role in the</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> development </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> of colon cancer? </span><br />
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<b>Summary:</b>A 45-year-old man with a family history of colon cancer underwent colonoscopy for rectal bleeding. Colonoscopic findings included several small pedunculated polyps in the right colon, all measuring less than 5 mm.</blockquote>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ <u>Most likely diagnosis:</u> Hyperplastic polyps or tubular adenomas.</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ <u>Syndromes predisposing to colon cancer:</u> Familial adenomatous</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> polyposis (FAP) and hereditary nonpolyposis <a href="http://www.amazon.com/American-Cancer-Societys-Complete-Colorectal/dp/0944235557?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">colon cancer</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=0944235557" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> (HNPCC)</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are two common inherited colon cancer syndromes.</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">◆ <u>Dietary factors that play a role in the development of colon</u></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <u>cancer:</u></span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Diets rich in fat and red meat and low in fiber may</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> contribute to the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">development of colon cancer.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>CLINICAL CORRELATION</u></b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Learn it for your USMLE..... Another Clinical Vignette with lots of explanation...</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Colon cancer is the third most common malignant neoplasm worldwide and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">the second leading cause of cancer death in the United States. The peak inci</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dence is in the seventh decade of life. Recommended screening for colon </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">cancer for patients without increased risk starts at age 50, but for at-risk </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">patients with a positive family history, screening should start at age 40 (</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">some recommend 10 years earlier than the age at which the youngest</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">index case presents). Annual fecal occult blood tests should be performed as </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">well as digital rectal examination and flexible <a href="http://www.amazon.com/Sigmoidoscopy-Explicit/dp/B004ADWETI?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">sigmoidoscopy</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B004ADWETI" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> every 5 years.</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Additional screening can be done by colonoscopy every 10 years, or a double </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">contrast barium enema can be done every 5 to 10 years. These recommended </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">screening intervals may be maintained after a negative examination. For </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">patients at high risk for cancer or with polyps, rescreening by colonoscopy at </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">3-year intervals is recommended. New technologies such as virtual colonog</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">raphy and genetic testing of stool specimens are being examined for their </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">appropriate clinical settings. In this patient, the colonic polyps showed prolif</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">eration of tubular glands, arising from a fibromuscular base with normal</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">colonic epithelium consistent with a polyp stalk. The polyps showed no evi</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dence of malignant transformation (i.e., carcinoma). The diagnosis was multi</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ple tubular adenomas of the colon.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>APPROACH TO COLON ADENOMAS</b></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Objectives</b></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">• <u>Describe the adenoma-dysplasia-carcinoma sequence.</u></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">• <u>List the risk factors for colon cancer.</u></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">• <u>Describe the hereditary polyp disorders.</u></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Definitions</u></b></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><i><b>Adenoma:</b></i> Neoplastic proliferation of colonic epithelium that results in the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">formation of a polyp.</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Neoplasia:</i></b> Usually implies abnormal, often clonal proliferation of cells </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">that results in the formation of a tumor.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Dysplasia:</i></b> Usually the result of additional genetic abnormalities in cells </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">that lead to further dysfunction or abnormal cell maturation.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Adenoma-dysplasia-carcinoma sequence:</i></b> Model for colon cancer devel</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">opment that outlines the genetic pathway involved in the progression </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">from a benign neoplastic polyp (adenoma) to frankly invasive cancer </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(carcinoma).</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Familial adenomatous polyposis syndrome:</i></b> The prototypic inherited</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">colon cancer phenotype; affected patients have hundreds to thousands of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">polyps and are at high risk for cancer development.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Hereditary nonpolyposis colorectal cancer:</i></b> Also known as Lynch syn</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">drome. Often presents as right-sided colon cancer and involves muta</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">tion in mismatch repair genes. It is inherited in an autosomal dominant </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">fashion, and affected individuals are also at high risk for extracolonic </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">malignancies such as endometrial carcinomas.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>DISCUSSION</u></b></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Polyps of the colon can be classified broadly into inflammatory /reactive, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hyperplastic, and neoplastic. Inflammatory polyps can be seen in chronic </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">colitides such as ulcerative colitis and Crohn disease. Hyperplastic polyps are </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">some of the more frequently encountered polyps and are thought to represent </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">nonneoplastic proliferation of colonic epithelium. There is accumulating evi</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dence that some hyperplastic polyps may transform to adenomas through a </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">serrated adenoma pathway. Adenomas are truly neoplastic proliferations and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">have the potential to transform and progress to carcinomas.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">With increasing age, there is an increased incidence of adenoma formation. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Approximately 50 percent of patients who have one adenoma have additional </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">synchronous adenomas present. Most polyps are present in the rectosigmoid </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">colon, but with increasing age, there is a tendency to see more right-sided </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">involvement by polyps.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Types of Adenomas</u></b></span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Adenomas can be classified on the basis of the pattern of growth: whether they </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are flat, sessile, and broad without a stalk, or pedunculated and on a stalk.</span></div>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Histologically, depending on the extent of tubular gland formation versus fin</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">gerlike villous projections, they are classified as tubular adenomas, villous </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">adenomas, or tubulovillous adenomas.</span><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2_kvBDPPPQGT_-wNTsCdOJbl_O89sjqB7vQaovkWwtQLgOAX-8jYd2ElhB0s7peckMu9IRDG8oVthonrTpryir2y_lieHxIbLspu1IsDGy1hUFi0pVAvkvBAq1rqX73rNVYhRTobvrok/s1600/F1.large.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="207" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2_kvBDPPPQGT_-wNTsCdOJbl_O89sjqB7vQaovkWwtQLgOAX-8jYd2ElhB0s7peckMu9IRDG8oVthonrTpryir2y_lieHxIbLspu1IsDGy1hUFi0pVAvkvBAq1rqX73rNVYhRTobvrok/s400/F1.large.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Adenoma-carcinoma sequence</td></tr>
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><i>Polyposis and Inherited Colon Cancer Syndromes</i></b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Syndromes that involve the formation of multiple gastrointestinal polyps occur </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infrequently. Some, such as Peutz-Jeghers syndrome and Cowden disease, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are autosomal dominant, resulting in the formation of nonneoplastic </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hamartomatous polyps; others, such as Canada-Cronkhite syndrome, are not </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hereditary and result in multiple juvenile polyps. Other clinically significant </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">polyposis or colon cancer syndromes include familial adenomatous polypo</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sis and hereditary nonpolyposis colorectal cancer.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The autosomal dominant FAP gene on chromosome 5q21 contains the</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">tumor suppressor gene APC (adenomatous polyposis coli). Affected individuals </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">have hundreds to thousands of polyps, typically presenting in the left colon.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Almost all individuals with APC gene mutations eventually develop colon </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">cancer. Hence, carriers usually are candidates for prophylactic colectomy.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Recent studies have shown that cyclooxygenase inhibitors can suppress polyp </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">formation and possibly carcinoma development in patients with FAP.</span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>Adenoma-Dysplasia-Carcinoma Sequence</b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A variant of FAP is Gardner syndrome, which involves the formation of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">osteomas of the bone, desmoid fibromatosis. HNPCC also is known as </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Lynch syndrome, named after the gastroenterologist Dr. Henry Lynch. The </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">autosomal dominant inherited disease presents early in life, often with right-</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sided cancer, and can be associated with polyps, although much less numer</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ous (usually fewer than 10) than what is seen in FAP. Patients with HNPCC </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">are also at risk for extra–gastrointestinal tract tumors.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">There are also less-well-defined familial cancer syndromes involving glan</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">dular elements (adenocarcinomas) that are ssociated with a family history or </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">personal history of breast, ovarian, endometrial, or colon cancer.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">The development of colon cancer is a multifactorial process involving </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">not only predisposition genes but also factors such as diet (low-fiber foods, red </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">meat, and refined carbohydrates are nonfavorable), obesity, and inactivity.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Genetically, it is known that adenomas can progress and transform through </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">additional mutations (i.e., genetic “hits”) and progressively grow in size, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">increase in the degree of dysplasia, and acquire full malignant potential </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(carcinoma). Additional genes that have been shown to be involved in this </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">process include the K-ras oncogene, the DCC (deleted in colon cancer) adhe</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">sion molecule gene, and the p53 tumor suppressor gene.</span><br />
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Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-17367804678446693432010-12-15T01:26:00.000-08:002010-12-23T07:37:58.975-08:00Clinical Case: AIDS Patient With Headache, Photophobia, Nausea and Weakness<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b><u>Clinical Vignette:</u></b> A 38-year-old AIDS patient presents to his physician's office in Kansas City, Missouri, complaining of fever for the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">past week and an increasing headache. He also states that sunlight hurts his eyes and that he has been feeling </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">nauseated and weak. His past medical history is significant for Pneumocystis pneumonia and a total CD4 count of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">89. Current medications are <a href="http://www.amazon.com/Aqua-Sulfa-800mg-Sulfamethoxazole-160mg-Trimethoprim/dp/B002WPNXDC?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">trimethoprim/sulfa</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B002WPNXDC" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> and <a href="http://www.amazon.com/Indan-Donepezil-Indacaterol-Aminodihydroindendicarbons%C3%A4ure-Atipamezol/dp/1159063842?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">indinavir</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=1159063842" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />. Cerebrospinal fluid (CSF) reveals 4 WBC, and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">budding encapsulated yeast forms grow on Sabouraud's agar. Which of the following is an accurate description </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">of the morphology of the infectious form of the organism responsible for the man's illness? </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Broad-based, budding yeasts </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. Budding yeasts in a "pilot's wheel" arrangement</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Cylindrical arthroconidia </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Encapsulated budding yeasts </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Filamentous molds </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>F</b>. Septate hyphae with microconidia and macroconidia </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>Explanation: </b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is D.</b> This clinical vignette has some nice info for USMLE, LEARN everything about HIV/AIDS. This is a classic case of Cryptococcus neoformans meningitis. Clues included the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">patient population (HIV positive), geographic area (Mississippi and Missouri river beds), and diagnostic form (</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">encapsulated yeast). <a href="http://www.amazon.com/Harrisons-Infectious-Diseases-ebook/dp/B003WJR5WC?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Cryptococcus </a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B003WJR5WC" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />is a monomorphic fungus, unlike many of the classic pathogens within the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">fungal group, so the encapsulated yeast form would be found both in clinical specimens and in the environment </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">as the infectious form. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Broad-based, budding yeasts (choice A) would be the forms expected to be found in clinical specimens (not </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">environmental forms) from patients infected with Blastomyces dermatitidis, which is far more likely to present </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">with skin and bone lesions than with meningitis. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Budding yeasts in a "pilot's wheel" arrangement (choice B) would be the form expected to be found in clinical </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">specimens (not environmental forms) from patients infected with Paracoccidioides brasiliensis, which is limited in </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">geographic region to Central and South America and typically presents as a primary pulmonary disease. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Cylindrical arthroconidia (choice C) would be the transmission forms characteristic of Coccidioides immitis, w</span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hich may be a cause of fungal meningitis in immunologically compromised individuals, but is geographically </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">restricted to the sub-Sonoran desert zone of the U.S. (San Joaquin valley fever). </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Filamentous molds (choice E) are the transmission forms of several of the fungal agents (eg, Coccidioides, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Blastomyces, Paracoccidioides) but Cryptococcus does not have a filamentous form. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Septate hyphae with microconidia and macroconidia (choice F) are the transmission (environmental) forms of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Histoplasma capsulatum, which is not an encapsulated yeast in spite of its name. It is primarily a pulmonary </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infection acquired by exposure to the droppings of birds or bats.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-25958705895022731622010-12-15T01:12:00.000-08:002010-12-15T01:16:39.446-08:00Diarrhea After Eating Raw Oysters<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A 57-year-old fisherman with a history of alcoholism is hospitalized in Gulfport, Mississippi with a 1-day history of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">severe, watery <a href="http://www.amazon.com/Imodium-A-D-Anti-Diarrhea-72-Count-Caplets/dp/B000FVOMVM?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">diarrhea</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B000FVOMVM" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> after eating several raw oysters. He is badly dehydrated on admission, and within 12 </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hours, he becomes severely hypotensive and dies. Which of the following pathogens is the most likely cause of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">this man's death? </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Citrobacter diversus </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. Enterotoxigenic E. coli </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Providencia stuartii </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Vibrio cholerae </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Vibrio vulnificus </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b> Explanation: </b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is E.</b><a href="http://www.amazon.com/Official-Patients-Sourcebook-Vulnificus-Infection/dp/0597829764?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Vibrio vulnificus</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=0597829764" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> is an extremely invasive organism, producing a septicemia in patients </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">after eating raw shellfish, or causing wound infections, cellulitis, fasciitis, and myositis after exposure to </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">seawater or after cleaning shellfish. Patients at high risk for septicemia include those with liver disease, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">congestive heart failure, diabetes mellitus, renal failure, hemochromatosis, and immunosuppression. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Citrobacter diversus(choice A) produces neonatal meningitis and can be frequently cultured from the umbilicus. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Enterotoxigenic E. coli(choice B) produces the classic <a href="http://www.amazon.com/Anti-Diarrheal-Loperamide-Hydrochloride-800-Caplets/dp/B00471400O?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">traveler's diarrhea</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B00471400O" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />. The toxin is ingested in water and </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">salads. The incubation period is approximately 12 hours. The diarrhea is non-inflammatory and treatment is </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">supportive. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Providencia stuartii(choice C) is a gram-negative rod related to Proteus. It is a common cause of nosocomial </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">bacteremia in nursing home patients with chronic catheterization. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <a href="http://www.amazon.com/Cholera-Ecology-Vibrio-cholerae-ebook/dp/B000PY3P8K?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">Vibrio cholerae</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B000PY3P8K" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />(choice D) produces a non-invasive, non-inflammatory, high-volume secretory diarrhea that is </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">toxin-mediated.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-73646573988740007522010-12-15T01:02:00.000-08:002010-12-15T01:02:40.945-08:00Acute Gastric Ulcer After A Motor Vehicle Accident<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A 35-year-old female, hospitalized after a motor vehicle accident, develops acute gastric stress ulcers. Increases </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">in which of the following normal physiological parameters may have contributed to this condition? </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Bicarbonate transport </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. Epithelial regenerative capacity </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Mucosal blood flow </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Mucus secretion </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Pepsin production </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>Explanation: </b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is E.</b> Pepsin production is a normal physiologic activity of the stomach that, in conditions of </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">stress, may overwhelm the stomach's weakened defenses and result in gastric ulceration. Gastric acid </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">production is another condition that may increase and cause <a href="http://www.amazon.com/American-Natural-Nopalton-Digestive-Cleanser/dp/B002RV6VXA?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">gastric ulceration</a>.<img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B002RV6VXA" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" /> Furthermore, these two factors </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">may remain unchanged and still result in gastric ulcers if the gastric defenses are weakened by stress.</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> All of the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">other choices represent normal defensive forces in the stomach. Increased bicarbonate transport (choice A) would protect the gastric epithelium from the potentially harmful </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">acidity of the gastric contents. The adherent mucus is relatively alkaline, providing local protection to the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">superficial mucosa. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Gastric epithelial cells can normally replicate rapidly, allowing mucosal defects to be rapidly repaired. Increasing </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">the regenerative capacity of the epithelium (choice B) would have a protective effect against ulceration. </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> The gastric mucosa is richly supplied with blood, providing the epithelial cells with an ample supply of nutrients, </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">oxygen, and bicarbonate to contend with the harsh gastric microenvironment. Stress ulcers are associated with </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">compromised gastric blood flow, not increased flow (choice C). </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Mucus protects the gastric epithelium by virtue of being water insoluble, impermeable to pepsin, and slowly </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">permeated by acid (H+). Increasing mucus production (choice D) has a protective effect for the gastric mucosa. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-21656197467012756192010-12-15T00:52:00.000-08:002010-12-15T00:52:08.594-08:00Cause Of Apical Cavitating Lung Lesions<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A patient comes in to the doctor because of a chronic cough. He notes occasional streaks of blood in his sputum. </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Chest x-ray reveals multinodular, cavitating lesions in the apical posterior segments of both lungs with evident </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">satellite lesions. The condition described is likely to occur in the apices of the lungs because they </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. are better perfused than the base </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. are more acidic than the base </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. contain more alveolar macrophages than the base </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. have a higher PO2 than the base </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. ventilate better than the base </span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> Explanation: </b></span><br />
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<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>The correct answer is D.</b> The presentation is typical for reactivation pulmonary tuberculosis. The patient may </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">also note fever, malaise, and weight loss. The high PO2 found in the upper portion of the lungs provides a </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">favorable environment for growth of Mycobacterium tuberculosis, leading to reactivation <a href="http://www.amazon.com/Tuberculosis-Simon-Schaaf-MBChB-Stellenbosch/dp/1416039880?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank">tuberculosis</a><img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=1416039880" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />. (In </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">contrast, primary tuberculosis tends to occur in the lower and middle lobes, where small infectious particles are </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">most likely to lodge after being inhaled.) </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Ventilation increases from the top to the bottom of the lung, so choice E is wrong. Perfusion increases even </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">more rapidly than ventilation, so choice A is also wrong. As a result, the ventilation-perfusion ratio decreases </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">from the top to the bottom of the lung. The higher ratio at the apex of the lung results in a relatively elevated </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">PO2 at that location. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> The apex of the lung has a higher pH than the base, so choice B is wrong. Because the ventilation-perfusion </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">ratio is higher at the apex, PCO2 would be lower, thus increasing the pH. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Regional differences in the density of alveolar macrophages (choice C) are not known to cause the described </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">predisposition. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-80138292657666868812010-12-15T00:36:00.000-08:002010-12-15T00:41:23.900-08:00Morbidly Obese Man With Respiratory Distress<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A morbidly obese (450 lb) individual presents to the emergency department in respiratory distress. Arterial blood gas studies show a PCO2 of 55 mm Hg, a PO2 of 60 mm Hg, and a pH of 7.28. Chest X-ray films are unremarkable, with no evidence of emphysema, tumor, fibrosis, pulmonary infarction, or other disease. Auscultation reveals a rapid but regular heart beat, and the pulse is strong. Which of the following is the most likely explanation of the patient's arterial hypoxemia? </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. Decreased capacity for pulmonary diffusion </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b>B</b></span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">. Decreased surface area of alveolar capillary membranes </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. Hypoventilation of central origin </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. Hypoventilation of peripheral origin </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. Inequalities of ventilation and perfusion </span><br />
<br />
<br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>Explanation: </b></span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> The correct answer is D.</b> It is conceptually worth subclassifying hypoxemia in terms of the groups of the causes listed in the answers. In this case, the patient has no evidence of primary pulmonary or cardiovascular disease, and is known to be morbidly obese. Morbidly obese individuals are vulnerable to the </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><a href="http://www.amazon.com/Pickwickian-Syndrome-Challenge-Statistical-Included/dp/B0008IYCY4?ie=UTF8&tag=clinivigne-20&link_code=btl&camp=213689&creative=392969" target="_blank"><b>Pickwickian Syndrome</b></a> </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">(after a character in a Dickens novel), in which pressure from a fatty neck causes in<img alt="" border="0" height="1" src="http://www.assoc-amazon.com/e/ir?t=clinivigne-20&l=btl&camp=213689&creative=392969&o=1&a=B0008IYCY4" style="border: none !important; margin: 0px !important; padding: 0px !important;" width="1" />termittent airway obstruction. The many other causes of hypoventilation of peripheral origin include suffocation, submersion, skeletal abnormalities, trauma, phrenic nerve paralysis, polio, and tetanus. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Causes for decreased capacity for pulmonary diffusion (choice A) of 02 include processes such as respiratory distress syndrome, emphysema, pulmonary fibrosis, and some granulomatous processes such as sarcoidosis. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Causes for decreased surface area of alveolar capillary membranes (choice B) include resection or </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">compression of the lung and emphysema. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> The usual cause of hypoventilation of central origin (choice C) is respiratory center depression by morphine or barbiturates. </span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Causes for inequalities of ventilation and perfusion (choice E) include chronic bronchitis, asthma, emphysema, bronchiectasis, some granulomatous processes, and tumors.</span>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.comtag:blogger.com,1999:blog-7781700110041904099.post-27823182730838967912010-12-14T07:57:00.000-08:002010-12-14T07:59:12.954-08:00Alcoholic With Lobar Consolidation<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">A 57-year-old alcoholic is hospitalized in the intensive care unit after a multivehicle accident. Twenty </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">hours after the accident, the patient develops a fever and a cough productive of purulent sputum. If a chest </span><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">radiograph shows lobar consolidation and the sputum reveals the presence of gram-negative encapsulated rods, the most appropriate initial therapy would be </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>A</b>. cefotaxime IV </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>B</b>. erythromycin IV </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>C</b>. gentamicin IV + vancomycin IV </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>D</b>. ticarcillin-clavulanic acid IV + vancomycin IV </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>E</b>. trimethoprim-sulfamethoxazole PO </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"></span><br />
<a name='more'></a><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><b> Explanation: </b></span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> <b>The correct answer is A.</b> The patient is presenting with signs and symptoms of pneumonia. Since the </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">patients signs and symptoms are appearing 20 hours after admission, his pneumonia is most likely a "community-acquired" pneumonia; one of the criteria for diagnosing a nosocomial infection is that the </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">infection must not occur before 48 hours after admission. The appearance of plump gram-negative encapsulated rods in an alcoholic is highly suggestive of Klebsiella pneumonia. The most appropriate treatment of Klebsiella pneumonia in this patient is the administration of a third-generation cephalosporin, such as cefotaxime, ceftriaxone, or ceftazidime. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Erythromycin (choice B) is a macrolide antibiotic used in the treatment of a variety of gram-negative </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">and gram-positive infections. Although it is not the treatment of choice in this patient, it is the treatment of </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">choice of Legionella pneumonia. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Gentamicin (choice C) is an aminoglycoside antibiotic that is generally added to improve the efficacy </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">of broad spectrum antibiotics, such as penicillin and cephalosporins, in the treatment of Pseudomonas and </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">Enterococcus infections. </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"> Vancomycin (choices C and D) is an antibiotic used in the treatment of life-threatening infections </span><br />
<span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;">caused by gram-positive infections; the use of this agent in a gram-negative infection is inappropriate. </span><br />
<div><span class="Apple-style-span" style="font-family: 'Courier New', Courier, monospace;"><br />
</span></div><div><br />
</div>Anonymoushttp://www.blogger.com/profile/07481607717351259460noreply@blogger.com