Nokea
With respect to vaccination against a particular infectious disease 'herd immunity' refers to:
- A. The total number of people who are immunized in a given population
- B. The protection offered to non-immunized people when high rates of immunization prevent the pathogen from spreading
- C. The percentage of people who generate a protective response to the vaccine
- D. The tendency of people to choose to be vaccinated if close contacts (friends and family) have been vaccinated
Correct Answer: B
Rationale: The correct answer is B. Herd immunity refers to the protection offered to non-immunized individuals when a high percentage of the population is immunized, preventing the pathogen from spreading easily. This is because when a large portion of the population is immune to a disease, it creates a barrier that reduces the overall transmission of the pathogen, thus protecting those who are not vaccinated or cannot be vaccinated.
Choice A is incorrect because herd immunity is not solely about the total number of immunized individuals, but rather about the impact on the entire population. Choice C is incorrect as it refers to the efficacy of the vaccine in generating a protective response, not the concept of herd immunity. Choice D is incorrect as it relates to social influence rather than the collective protection provided by high rates of immunization.
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Which of the following is a characteristic of CTL?
- A. They kill target cells through recognition of peptide-MHC class I complexes
- B. They die in the process of killing a target cell
- C. They can kill target cells by activating complement
- D. They carry out their effector function in secondary lymphoid tissues
Correct Answer: A
Rationale: The correct answer is A because cytotoxic T lymphocytes (CTLs) kill target cells by recognizing specific peptide antigens presented on major histocompatibility complex (MHC) class I molecules. This recognition triggers the CTLs to release cytotoxic molecules that induce apoptosis in the target cells. Choice B is incorrect because CTLs do not die in the process of killing target cells; they survive to continue their immune response. Choice C is incorrect as CTLs do not kill target cells by activating complement, but rather through direct cell-cell contact. Choice D is incorrect because CTLs carry out their effector function in peripheral tissues where they encounter target cells, not specifically in secondary lymphoid tissues.
While caring for an HIV-positive patient who is hospitalized with Pneumocystis carinii pneumonia,you note that all of these drug therapies are scheduled for 10:00 AM. Which nursing action is most essential to accomplish at the scheduled time?
- A. Administer the protease inhibitor indinavir (Crixivan) 800 mg PO.
- B. Infuse pentamidine (Pentam-300) 300 mg IV over 60 minutes.
- C. Have the patient “swish and swallow” nystatin (Mycostatin) 5 mL.
- D. Apply acyclovir (Zovirax) cream to oral herpes simplex lesions.
Correct Answer: B
Rationale: Pentamidine is a critical medication for treating Pneumocystis carinii pneumonia and must be administered on time to ensure therapeutic levels. The other medications while important can be administered slightly later if necessary without significantly impacting the patient’s condition.
The nurse is performing an assessment on the patient who is in bilateral Buck traction. Which finding indicates the need to reposition the patient?
- A. The patient's heels are not touching the surface of the mattress.
- B. The elastic bandages need to be revrapped.
- C. The patient's feet are against the footboard.
- D. The weights are hanging free.
Correct Answer: C
Rationale: The correct answer is C because if the patient's feet are against the footboard in Buck traction, it can cause pressure ulcers and compromise circulation. Repositioning the patient is necessary to ensure proper alignment and prevent complications.
Incorrect choices:
A: The patient's heels not touching the mattress can be due to the traction pulling the legs in a specific position.
B: Rewrapping the elastic bandages may be necessary for proper traction maintenance but doesn't indicate immediate need for repositioning.
D: The weights hanging free is a normal finding in Buck traction and indicates proper traction application.
Which of the following is NOT a function of innate immunity?
- A. Killing virally infected cells
- B. Phagocytosis
- C. Activating adaptive immunity
- D. Producing antigen-specific antibodies
Correct Answer: D
Rationale: The correct answer is D. Innate immunity does not involve producing antigen-specific antibodies. This is because innate immunity is the first line of defense against pathogens and does not have the ability to produce antibodies that target specific antigens. Instead, innate immunity works through mechanisms like phagocytosis and killing infected cells to eliminate pathogens. Choices A, B, and C are functions of innate immunity. A - Killing virally infected cells is a common function of innate immunity. B - Phagocytosis is the process by which immune cells engulf and destroy pathogens, a key function of innate immunity. C - Activating adaptive immunity is also a role of innate immunity, as it helps initiate the adaptive immune response for a more targeted defense.
Terminal deoxynucleotidyl transferase catalyzed reactions produce fragments with
- A. poly A or poly C tails
- B. poly C tails
- C. poly A tails
- D. poly A or poly T tail
Correct Answer: A
Rationale: Terminal deoxynucleotidyl transferase (TdT) adds nucleotides to the 3' end of DNA fragments in a template-independent manner. This results in the production of fragments with poly A or poly C tails. TdT does not add poly T tails, making option D incorrect. It also does not specifically add only poly C tails (option B) or poly A tails (option C). The addition of poly A or poly C tails by TdT is essential for techniques like DNA sequencing and PCR, where these tails are utilized for downstream applications.