MEDSTUDENTS - USMLE Step 1 Questions and Answers
(A) Incorrect.
(B) Incorrect.
(C) Incorrect
(D) CORRECT. Behavioral desinhibition is a feature of early intoxication due to ethanol and most other alcohols, but not ingestion of the solvent, hexane. Ocular dysfunction, including horizontal nystagmus and diplopia, is also a common finding in poisoning with alcohols, but the complaint of "flickering white spots before the eyes" or "being in a snowstorm" is pathognomonic for methanol intoxication. In some cases, the odor of formaldehyde may be present on the breath. In the patient, blood methanol levels should be determined as soon as possible.
(E) Incorrect.
(A) Incorrect.
(B) CORRECT. In all poisonings situations, it is important to establish adequate respiration. Bicarbonate may be needed to counteract metabolic acidosis. In patients with suspected methanol intoxication, ethanol (10%) is often given intravenously -before laboratory diagnosis is confirmed, to block the formation of toxic products of ADH-catalyzed metabolism of methanol. Blood levels of methanol in excess of 50 mg/dL are an absolute indication of hemodialysis. Activated charcoal does not bind alcohols.
(C) Incorrect.
(D) Incorrect.
(E) Incorrect.
(A) Incorrect.
(B) Incorrect..
(C) CORRECT. Examination of the peripheral blood smear is essential when evaluating a patient for thrombocytopenia. Unreported abnormalities of red cells may offer a clue to the etiology, or occasionally one may find a discrepancy between the number of platelets seen on the smear and that found by the automated count. This occurs in pseudothrombocytopenia, where clumping of platelets in a specific anticoagulant (usually EDTA) results in marked underestimation of the count.
(D) Incorrect.
(E) Incorrect.
(A) Incorrect.
(B) CORRECT. Psychological and physical dependence may occur with chronic use of caffeine. Withdrawal symptoms include headache, lethargy, depression, and increased appetite. Insomnia is associated with the use of caffeine rather than caffeine withdrawal.
(C) Incorrect.
(D) Incorrect
(E) Incorrect.
(A) Incorrect.
(B) Incorrect.
(C) CORRECT.
(D) Incorrect.
(E) Incorrect.
(A) Incorrect.
(B) Incorrect
(C) Incorrect
(D) CORRECTt
(E) Incorrect.
(A) CORRECT. Streptococcus pyogenes causes increased production of IL-1 in macrophages. IL-1 acts on the anterior hypothalamus to increase production of prostaglandins, which increase the hypothalamic set-point temperature. The hypothalamus the "reads" the core temperature as being lower than the new set-point temperature, and activates various heat-generating mechanisms that raise body temperature (fever). These mechanisms include shivering and vasoconstriction of blood vessels in the skin.
(B) Incorrect.
(C) Incorrect.
(D)Incorrect.
produced from VLDL.
(E) Incorrect
(A) Incorrect.
(B) Incorrect.
(C) CORRECT. By inhibiting cyclo-oxigenase, aspirin inhibits the production of prostaglandins and brings the hypothalamic set-point back down to its original value. This activates heat loss mechanisms: sweating, vasodilatation of blood vessels.
(D) Incorrect.
(E) Incorrect
(A) Incorrect.
(B) CORRECT. EBV is associated with nasopharyngeal carcinoma. It is also associated with Burkitt's lymphoma and with infectious mononucleosis, a benign, self-limited lymphoproliferative disoreder.
(C) Incorrect. .
(D) Incorrect.
(E) Incorrect
(A) Incorrect.
(B)CORRECT. The jaundice of hemolytic anemia is due to increased unconjugated bilirrubin. Since unconjugated bilirrubin is not excreted into the urine, the type of juandice is acholuric, jaundice without bilirrubin pigment in the urine.
(C) Incorrect.
(D) Incorrect.
(E) Incorrect. .