Biguanides are used in the following conditions EXCEPT:

Correct Answer: D

Rationale: Step-by-step rationale for why choice D is correct: 1. Biguanides like metformin are not used in hyperglycemic shock due to their slower onset of action. 2. In hyperglycemic shock, rapid-acting medications like insulin are needed for immediate correction. 3. Choices A, B, and C are incorrect because biguanides are commonly used as an initial treatment for type 2 diabetes to improve insulin sensitivity and reduce glucose production in the liver.

Correct Answer: D

Rationale: The correct answer is D because I.V. IgG preparations compete for Fc receptors with autoantibodies. This blocks the binding of autoantibodies to their target antigens, thereby preventing autoimmune reactions. Choice A is incorrect as I.V. IgG does not inhibit CD3 receptors. Choice B is incorrect as it does not inhibit calcineurin. Choice C is incorrect as I.V. IgG does not induce complement-mediated cytolysis of T lymphocytes.

Correct Answer: A

Rationale: The correct answer is A: Scurvy is a disease caused by a deficiency of vitamin C. This deficiency leads to symptoms such as spongy bleeding gums, bleeding under the skin, and weakness. - Choice B is incorrect because extreme dryness of the conjunctiva is not a symptom of scurvy, and it is more related to a deficiency of vitamin A. - Choice C is incorrect because it describes symptoms of pellagra, a disease caused by a deficiency of niacin, not scurvy. - Choice D is incorrect because it includes all the incorrect options, making it incorrect as well. In summary, the correct choice (A) accurately describes the cause and symptoms of scurvy, while the other choices describe different diseases with unrelated symptoms.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Cholesterol synthesis inhibitors, like statins, reduce cholesterol production in the liver, leading to an upregulation of LDL receptors on hepatocytes. This increases the clearance of LDL cholesterol from the plasma, ultimately lowering LDL levels. Therefore, the statement that cholesterol synthesis inhibitors increase the rate of clearance of LDL cholesterol from the plasma is true. Choices B, C, and D are incorrect because they do not accurately reflect the relationship between cholesterol synthesis inhibitors and LDL cholesterol clearance.

Correct Answer: B

Rationale: The correct answer is B: Rickets. Calcifediol is administered for the treatment of vitamin D deficiency-related conditions like rickets, which is a bone disorder caused by a lack of vitamin D, leading to soft and weak bones. The other choices are incorrect because: A) Primary hyperparathyroidism is treated with medications that target the parathyroid gland, not vitamin D. C) Hypercalcemia is an excess of calcium in the blood and is not treated with calcifediol since it can exacerbate the condition. D) Failure of vitamin D formation in the skin is not an indication for calcifediol administration as it is used to treat vitamin D deficiency, not a failure in its formation.