All of the following statements concerning the fibric acid derivatives are true, EXCEPT:

Correct Answer: C

Rationale: The correct answer is C. Gemfibrozil (Lopid) has not been shown to reduce mortality associated with heart disease. This statement is false as fibric acid derivatives, including gemfibrozil, primarily work by lowering triglycerides and increasing HDL cholesterol levels, which may help in reducing the risk of heart disease but not mortality directly. Choices A, B, and D are all true statements about fibric acid derivatives. A: Clofibrate is indeed used for Type III hyperlipidemia. B: Gemfibrozil increases HDL cholesterol and lowers LDL cholesterol. D: Gemfibrozil is generally well tolerated with common side effects being gastrointestinal upset and myopathy.

Correct Answer: B

Rationale: Step 1: Plicamycin inhibits RNA synthesis in cancer cells, leading to myelosuppression. Step 2: Myelosuppression results in decreased production of blood cells, causing anemia, thrombocytopenia, and neutropenia. Step 3: Diarrhea is not a common adverse effect of plicamycin. Step 4: Nephrolithiasis and metastatic calcifications are not directly associated with plicamycin use.

Correct Answer: B

Rationale: The correct answer is B: Enlarged uptake of the drug by a microorganism. This is incorrect because mechanisms of bacterial resistance involve reducing the uptake of the drug (choice D), modifying the drug's target (choice C), and actively transporting the drug out of the microorganism or hydrolyzing it with enzymes (choice A). Enlarged uptake would actually make the bacteria more susceptible to the antimicrobial agent, not resistant.

Correct Answer: D

Rationale: The correct answer is D. Sulfonamides inhibit folic acid synthesis, which is essential for the growth of bacteria, Chlamydia, Actinomyces, and some protozoa. This mechanism makes them effective against all the mentioned microorganisms. Choice A is incorrect because it does not include protozoa. Choice B is incorrect because sulfonamides are effective against Actinomyces. Choice C is incorrect because sulfonamides are not effective against all protozoa.

Correct Answer: B

Rationale: The correct answer is B: Diloxanide. Diloxanide is the drug of choice for treating the asymptomatic intestinal form of amebiasis because it acts specifically against the trophozoites in the lumen of the intestine without affecting the cysts. Chloroquine (A) is used for malaria, emetine (C) is used for invasive amebiasis, and doxycycline (D) is an antibiotic not typically used for amebiasis.