Which of the following antimicrobial which acts by interfering with DNA * function in the bacteria and can cure most cases of uncomplicated gonorrhea?:

Correct Answer: B

Rationale: The correct answer is B: Ciprofloxacin. Ciprofloxacin is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase, an enzyme crucial for bacterial DNA replication and repair. By interfering with DNA function, it disrupts bacterial growth and can effectively treat most cases of uncomplicated gonorrhea. Rationale: A: Chloramphenicol inhibits protein synthesis, not DNA function. C: Streptomycin inhibits protein synthesis by binding to the bacterial ribosome. D: Erythromycin also inhibits bacterial protein synthesis and is not primarily targeted at DNA function.

Correct Answer: B

Rationale: The main reason for using combination therapy in tuberculosis treatment is to delay or prevent the emergence of resistance. By using multiple drugs that target different aspects of the bacteria's life cycle, it becomes harder for the bacteria to develop resistance to all drugs simultaneously. This helps to ensure that the treatment remains effective in the long term. Explanation for other choices: A: While combination therapy can sometimes help reduce side effects by using lower doses of each drug, the primary reason for using it in tuberculosis treatment is to prevent resistance, not side effects. C: While combination therapy can increase antimycobacterial activity, the main goal is to prevent resistance, not to enhance the drugs' effects. D: Providing prophylaxis against other bacterial infections is not the main reason for using combination therapy in tuberculosis treatment; the focus is on preventing resistance.

Correct Answer: B

Rationale: The correct answer is B. Alprostadil is a prostaglandin E1 analogue that works by increasing cyclic guanosine monophosphate (cGMP) levels. This leads to smooth muscle relaxation and vasodilation, which helps in treating conditions like erectile dysfunction. Choice A is incorrect because alprostadil does not primarily increase cyclic adenosine monophosphate (cAMP). Choice C is incorrect as there is no known mechanism of action involving PD for alprostadil. Choice D is an incomplete option and not a valid answer.

Correct Answer: B

Rationale: The correct answer is B: Lithium. Lithium is known to cause nephrogenic diabetes insipidus, a condition where the kidneys are unable to respond to antidiuretic hormone (ADH), leading to excessive urination and thirst. This is due to lithium disrupting the normal function of the kidneys in retaining water. Diazepam (A) is a benzodiazepine used for anxiety and does not affect ADH secretion. Haloperidol (C) is an antipsychotic that can cause hyperprolactinemia but not inappropriate ADH secretion. Phenytoin (D) is an anticonvulsant and does not impact ADH secretion.

Correct Answer: B

Rationale: The correct answer is B: Thiazides. Thiazides inhibit the Na+Cl- transporter in the distal convoluted tubule of the kidney, leading to increased excretion of sodium and water. This results in diuresis and decreased blood pressure. A: Spironolactone acts on the aldosterone receptor in the collecting duct, not on the Na+Cl- transporter in the distal convoluted tubule. C: Furosemide and D: Ethacrynic acid act on the Na-K-2Cl symporter in the thick ascending limb of the loop of Henle, not on the Na+Cl- transporter in the distal convoluted tubule.