Nokea
Which of the following interferes with mycolic acid synthesis an essential component of mycobacterial cell walls for which resistance will develop rapidly if the drug is used alone?
- A. Isoniazid
- B. Rifampicin
- C. Pyrazinamide
- D. Ethanbutol
Correct Answer: A
Rationale: The correct answer is A: Isoniazid. Isoniazid inhibits the synthesis of mycolic acid, a crucial component of mycobacterial cell walls. If used alone, resistance can develop rapidly due to its specific mechanism of action. Rifampicin (B) acts on RNA polymerase, not mycolic acid synthesis. Pyrazinamide (C) targets mycobacteria in acidic environments, not mycolic acid. Ethambutol (D) inhibits arabinosyltransferase, not mycolic acid synthesis.
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The process by which water is reabsorbed by following solutes when they are reabsorbed is called
- A. obligatory water reabsorption
- B. facultative water reabsorption
- C. osmotic water reabsorption
- D. renin-angiotensin water reabsorption
Correct Answer: B
Rationale: The correct answer is B: facultative water reabsorption. This process occurs in the collecting ducts of the nephron in the kidney, where water reabsorption is regulated based on the body's hydration levels. When solutes like sodium are reabsorbed, water follows passively through aquaporin channels, adjusting the amount of water reabsorbed according to the body's needs.
A: Obligatory water reabsorption refers to the constant reabsorption of water in the proximal tubule and descending loop of Henle, not regulated based on hydration levels.
C: Osmotic water reabsorption is a general term referring to the movement of water based on osmotic gradients, not specifically regulated by solute reabsorption.
D: Renin-angiotensin water reabsorption involves the renin-angiotensin-aldosterone system in response to low blood pressure, focusing on sodium reabsorption rather than direct regulation of
Which of the following antifungal agent act as fungicidal by inhibiting the * synthesis of β1,3 glucan used for the disseminated mucocutaneous Candida infections?
- A. Caspofungin
- B. Amphoterecin B
- C. Flucytosine
- D. Ketoconazole resistance rapidly?:
Correct Answer: A
Rationale: Rationale:
Caspofungin is a echinocandin antifungal that inhibits the synthesis of β1,3 glucan in the fungal cell wall, leading to cell death. This mechanism makes it fungicidal against Candida infections. Amphotericin B disrupts fungal cell membranes, while Flucytosine interferes with DNA/RNA synthesis. Ketoconazole inhibits ergosterol synthesis. Therefore, A is correct as it targets the specific mechanism for Candida infections.
Antiviral agents that is/ are active against cytomegalovirus (CMV) include * which of the following?
- A. Ganciclovir
- B. Foscarnet
- C. Acyclovir
- D. (
Correct Answer: A
Rationale: Step-by-step rationale for choice A (Ganciclovir) being the correct answer:
1. Ganciclovir is a nucleoside analog that inhibits CMV DNA synthesis.
2. It is specifically approved for the treatment of CMV retinitis in immunocompromised patients.
3. Ganciclovir has a high specificity for CMV, making it an effective antiviral agent against CMV.
Summary of why the other choices are incorrect:
- Choice B (Foscarnet) is also active against CMV but is not as commonly used as Ganciclovir.
- Choice C (Acyclovir) is not effective against CMV as it primarily targets herpes simplex virus and varicella-zoster virus.
- Choice D ( ) is an incomplete choice and does not correspond to any known antiviral agent.
Which laboratory result is of most concern for a patient with cystitis?
- A. Serum WBC 9000/mm?
- B. Urinalysis with 1-2 WBCs present
- C. Urine bacteria 100,000 colonies/mL
- D. Serum hematocrit 36%
Correct Answer: C
Rationale: The correct answer is C because a urine bacteria count of 100,000 colonies/mL indicates a significant bacterial infection, which is concerning for cystitis. This result suggests an active infection in the urinary tract, requiring prompt treatment.
A: Serum WBC of 9000/mm³ is within the normal range and may not necessarily indicate an active infection.
B: Urinalysis with 1-2 WBCs present is also within the normal range and may not be indicative of an acute infection.
D: Serum hematocrit of 36% is a measure of the proportion of red blood cells in the blood and is not directly related to cystitis.
A 70 year old man has severe urinary hesitancy associated with BPH. He has tried alpha blockers with little effect. His physician recommends a drug that blocks 5α-reductase in the prostate which is:
- A. Leuprolide
- B. Finasteride
- C. Flutamide
- D. Ketoconazole
Correct Answer: B
Rationale: The correct answer is B: Finasteride. Finasteride is a 5α-reductase inhibitor that reduces the conversion of testosterone to dihydrotestosterone in the prostate, thereby shrinking the prostate gland and improving urinary symptoms in BPH. Leuprolide (A) is a GnRH agonist used in prostate cancer, not BPH. Flutamide (C) is an antiandrogen used in prostate cancer. Ketoconazole (D) is an antifungal drug and not indicated for BPH.