During a secondary humoral response:

Correct Answer: D

Rationale: During a secondary humoral response, memory B cells are activated, leading to a faster and more robust production of Ig antibodies than in the primary response. IgG antibodies, in particular, are produced in higher amounts and persist longer than IgM antibodies. This is because memory B cells are already primed to quickly differentiate into plasma cells upon re-exposure to the same antigen, resulting in a more rapid and efficient immune response. Therefore, choice D is correct. Choices A, B, and C are incorrect because they do not accurately reflect the characteristics of a secondary humoral response.

Correct Answer: C

Rationale: The correct answer is C: Hearing loss. Amikacin, an aminoglycoside antibiotic, is known to cause ototoxicity, which can manifest as hearing loss. The client should contact the PHCP immediately if hearing loss occurs as it may be a sign of irreversible damage. Nausea (A), lethargy (B), and muscle aches (D) are common side effects of Amikacin but are not urgent or indicative of a serious adverse reaction requiring immediate medical attention.

Correct Answer: C

Rationale: The correct answer is C: Desmopressin (DDAVP). This patient likely has von Willebrand disease, a common bleeding disorder. Desmopressin releases von Willebrand factor and factor VIII from endothelial cells, aiding in hemostasis. Factor VIII concentrate (A) is used for hemophilia A, not von Willebrand disease. Fresh frozen plasma (B) contains various clotting factors but is not specific for von Willebrand disease. Whole blood transfusion (D) is not necessary in this case and does not address the underlying issue.

Correct Answer: A

Rationale: The correct answer is A: CT scan of abdomen. In a 69-year-old man with weight loss, back pain, and hyperglycemia, a CT scan of the abdomen is the most likely diagnostic study to identify potential underlying causes such as pancreatic cancer or other abdominal malignancies. This imaging modality can provide detailed information on the pancreas, surrounding structures, and possible metastases. Summary: B: Glucose tolerance test is not the most appropriate initial study for a patient presenting with these symptoms. C: Colonoscopy is indicated for evaluating lower gastrointestinal symptoms, not typically for weight loss, back pain, and hyperglycemia. D: Whole-body PET scan may be used for cancer staging, but a CT scan of the abdomen is more specific for identifying abdominal malignancies.

Correct Answer: C

Rationale: The correct next diagnostic study for a 26-year-old man with testicular mass and periaortic lymphadenopathy is to measure α-fetoprotein, β-hCG, and LDH levels (Choice C). This is because these tumor markers (α-fetoprotein, β-hCG, LDH) are essential in the evaluation of testicular cancer. Elevated levels of these markers can indicate the presence of germ cell tumors. Needle biopsy of a retroperitoneal mass (Choice A) would not be the initial step as it does not directly evaluate the testicular mass. Needle aspiration of the testicular mass (Choice B) may yield limited information compared to tumor marker levels. PET scan (Choice D) is typically not the first-line investigation for testicular cancer evaluation.