Random USMLE Facts volume 7-2

Rahul's Noteblog Notes on USMLE facts, Exam Tips, and USMLE Lab Values Random USMLE Facts volume 7-2

Random USMLE Facts volume 7-2:

USMLE Facts 1	USMLE Facts 2	USMLE Facts 3	USMLE Facts 4	USMLE Facts 5
USMLE Facts 6	USMLE Facts 7	USMLE Facts 8	USMLE Facts 9	USMLE Facts 10

What would a superior orbital lesion cause?

Double vision, inability to adduct the left eye, and lack of corneal reflex on the left side.

What is the histological description of papillary thyroid cancer?

Branching papillae with a fibrovascular stalk lined by single or multiple layers of cuboidal epithelium. The nuclei of these epithelial cells have a characteristic ground glass appearance, and concentrically calcified structures (psammoma bodies) are present.

What is the histological description of follicular thyroid cancer?

Sheets of follicular cells or large cells with eosinophilic cytoplasm (Hurthle cells).

What is elastase?

Elastase is a neutral protease contained within macrophage lysosomes and in azurophil granules of neutrophils. Excess elastase activity in lungs is a cause of centriacinar and panacinar emphysema.

In MEN, why are multiple endocrine organs affected?

Because they all have the same embryological origin - neural crest cells. For example, in MEN I (pituitary/parathyroid/pancreas), both chromaffin cells of the adrenal medulla and parafollicular cells (C-cells) originate from the neural crest. The genetic defect associated with MEN 2A and 2B is a germ-line mutation from the RET proto-oncogene. Neural crest cells arise from the ectoderm at the margin of the neural tube. Then, they migrate to various locations through the body. In the end, neural crest cells form the thyroid and the adrenal medulla. So, a defect in one germ-line cell can produce both medullary thyroid cancers from parafollicular C-cells and pheochromocytomas from adrenal medullary cells.

How can some cells generate ribose from fructose-6-phosphate?

Using the enzyme transketolase.

What are some findings of aplastic anemia?

Pancytopenia, very low reticulocyte count, and lack of splenomegaly. Also note that aplastic anemia is marked by bone marrow hematopoietic elements that are replaced by fat cells and fibrous stroma. Bone marrow biopsy reveals a "dry tap."

What are the important immunological cells on sarcoidosis?

Cell-mediated immunity is driven by Th1 type CD4+ helper T cells which secrete IL-2 and INF-gamma. IL-2 stimulates the proliferation of Th1 cells and INF-gamma activates macrophages, promoting granuloma formation.

What are some findings in Reiter's syndrome?

Non-gonococcal urethritis, conjunctivitis, and artiritis. See: Notes on Musculoskeletal Disorders

How to determine if a particular gene is expressed?

Northern blot (target mRNA).

What is the usage of ELISA?

ELISA is used to measure the amount of protein in body fluids. For example, ELISA may be used to measure plasma insulin levels.

What is common with C. trachomatis and U. urealyticum?

They both lack peptidoglycan cell walls, hence, they cannot be treated with antibiotics that target peptidoglycan synthesis. C. trachomatis and U. urealyticum are better treated with agents like macrolides and tetracyclines.

What is the pathological cause of Dubin-Johnson syndrome?

Defective hepatocellular excretion of bilirubin glucuronides. This causes hepatocytes to accumulate abundant pigment inclusions in the lysosomes. Findings include occurrences of several episodes of intermittent self-resolving jaundice.

What is one way to minimize cyanide toxicity associated with nitroprusside usage?

Donate sulfur to liver rhonadase to enhance conversion of cyanide to thiocyanate.

What happens to CO₂ tension in a panic attack?

Decreases.

Infective endocarditis is caused by what two bacterial organisms?

• S. aureus: right-sided infective endocarditis in IV drug users. Complications may include perforations of the heart valves, rupture of the chordae tendineae, very high fevers, and septic embolism to the lung. There may be tricuspid regurgitation on transthoracic echocardiogram.
• S. viridans: infective endocarditis due to dental work.
• HACEK organisms: haemophilus, actinobacillus, cardiobacterium, eikenella, and kingella. These organisms can cause culture-negative infective endocarditis (negative blood cultures!). Findings may include mitral valve vegetation on transesophegal echocardiogram.

USMLE Facts 1	USMLE Facts 2	USMLE Facts 3	USMLE Facts 4	USMLE Facts 5
USMLE Facts 6	USMLE Facts 7	USMLE Facts 8	USMLE Facts 9	USMLE Facts 10

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