Proteins from two samples of animal blood, A and B, were tested by the double-diffusion (Ouchterlony) test in agar against antibody to bovine albumin. Which sample(s) contain horse blood?

Correct Answer: B

Rationale: The correct answer is B (sample B) because the double-diffusion test in agar against antibody to bovine albumin is specific for detecting the presence of bovine albumin. Since horse blood does not contain bovine albumin, sample B must contain horse blood. Sample A does not contain horse blood as it would not react with the antibody to bovine albumin. Both samples (C) cannot contain horse blood because the test is specific for bovine albumin. Neither sample (D) is incorrect because sample B does contain horse blood.

Correct Answer: D

Rationale: The correct answer is D. Naïve Th cells do not produce both gamma interferon and interleukin-4 simultaneously. They differentiate into Th-1 or Th-2 cells based on signals received. Th-1 cells produce gamma interferon and promote cell-mediated immunity, while Th-2 cells produce interleukin-4 and -5 and promote antibody-mediated immunity. Both Th-1 and Th-2 cells have CD3 and CD4 proteins, but this is not the least accurate statement among the choices.

Correct Answer: D

Rationale: The correct answer is D: protect the body against pathogens. White blood cells are a vital part of the immune system and play a key role in defending the body against infections and diseases caused by pathogens such as bacteria, viruses, and other harmful substances. They do this by identifying and destroying pathogens through various mechanisms like phagocytosis and producing antibodies. Choice A (transport oxygen to body cells) is incorrect because the function of transporting oxygen is primarily carried out by red blood cells. Choice B (produce hormones that regulate cell communication) is incorrect as white blood cells do not produce hormones for this purpose. Choice C (carry glucose to body cells) is incorrect because the transportation of glucose is mainly performed by the bloodstream and facilitated by insulin.

Correct Answer: C

Rationale: The correct answer is C: Standard precautions. Standard precautions are essential to prevent transmission of HIV, which spreads through blood and body fluids. These precautions include hand hygiene, personal protective equipment, safe injection practices, and proper disposal of sharps. Airborne precautions (choice A) are not necessary for HIV, as it is not transmitted through the air. Contact precautions (choice B) only during wound care are not sufficient, as HIV can be transmitted through various body fluids, not just wounds. Droplet precautions (choice D) are not appropriate for HIV, as it is not primarily spread through respiratory droplets. Therefore, standard precautions are the most effective and comprehensive approach to prevent HIV transmission.

Correct Answer: B

Rationale: The correct answer is B, as rifampin can cause skin and/or urine discoloration, turning them reddish-orange. This is a common side effect known as rifampin-induced discoloration. Choice A is incorrect because blurry vision is an adverse effect of ethambutol, not rifampin. Choice C is incorrect as rifampin does not improve hearing. Choice D is incorrect as sunlight sensitivity is not associated with rifampin. Therefore, understanding the potential side effect of skin discoloration is crucial for patient education regarding the new prescription for rifampin.