Which of the following signaling pathways likely mediates the therapeutic efficacy of oxytocin during labor induction?

Correct Answer: A

Rationale: The correct answer is A: Cyclic adenosine monophosphate (cAMP) synthesis. Oxytocin induces uterine contractions during labor by binding to its receptor and activating the G-protein coupled receptor, leading to increased cAMP synthesis. This results in the activation of protein kinase A, which ultimately leads to smooth muscle contraction in the uterus. Phosphoinositide hydrolysis (choice B) is not involved in oxytocin signaling. Cyclic guanosine monophosphate (cGMP) synthesis (choice C) is typically associated with nitric oxide signaling, not oxytocin. Tyrosine residue phosphorylation (choice D) is more related to growth factor signaling pathways, not oxytocin-induced labor contractions.

Correct Answer: D

Rationale: The correct answer is D: Cell nucleus. Levothyroxine acts by binding to thyroid hormone receptors in the cell nucleus, where it regulates gene expression. This is essential for controlling metabolism and energy production. Choices A, B, and C are incorrect because levothyroxine's mechanism of action does not involve the cell membrane, mitochondria, or smooth endoplasmic reticulum. The nucleus is where genetic material is stored and gene expression is controlled, making it the main site of action for levothyroxine.

Correct Answer: A

Rationale: The correct answer is A: Disorientation and lethargy. Inappropriate increase of drug dose can lead to drug toxicity, resulting in central nervous system depression. Disorientation and lethargy are common signs of CNS depression. Shallow breathing (choice B) may indicate respiratory depression, but it typically occurs after severe drug overdose. Unconsciousness (choice C) is a more severe manifestation that may occur after prolonged CNS depression. Severe pain in both legs (choice D) is unlikely to be directly related to drug overdose but may indicate an unrelated condition.

Correct Answer: A

Rationale: The correct answer is A: Fludrocortisone. Fludrocortisone is a synthetic mineralocorticoid used to treat adrenal insufficiency by replacing aldosterone. It helps regulate electrolyte balance and blood pressure. Edrophonium, Azathioprine, and Neostigmine are not mineralocorticoids and are used for different conditions like myasthenia gravis and autoimmune diseases.

Correct Answer: C

Rationale: The correct answer is C: To avoid opportunistic infections after surgery. Prednisone is a corticosteroid that suppresses the immune system, which can increase the risk of infections. Restarting prednisone post-surgery may be necessary to prevent opportunistic infections due to the patient's suppressed immune response. Choices A, B, and D are incorrect because adrenal insufficiency, wound healing, and gallbladder relaxation are not typically primary goals for restarting prednisone treatment in this context.