Concerning multiple sclerosis (MS), which of the following is NOT correct
- A. Some HLA alleles confer susceptibility to MS
- B. A gender bias is observed with females more at risk for MS than males
- C. Exhibits a North-South gradient, with a higher incidence reported for populations living above the equator
- D. Affects mostly individuals over 65 yrs. of age
Correct Answer: D
Rationale: The correct answer is D because multiple sclerosis (MS) typically affects individuals between 20-50 years old, with the most common age of onset being between 20-40 years. MS is not primarily a disease of older individuals over 65 years. Choices A, B, and C are incorrect because various HLA alleles have been associated with MS susceptibility, females are indeed more at risk for MS than males, and there is a known North-South gradient in MS incidence, with higher rates reported for populations living farther from the equator.
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The three antibiotic-resistant bacteria that are of most current concern in North America are ____________________, ____________________, and ____________________.
- A. Methicillin-resistant Staphylococcus aureus (MRSA)
- B. Carbapenem-resistant Enterobacteriaceae (CRE)
- C. Vancomycin-resistant Enterococcus (VRE)
- D. All of the above
Correct Answer: D
Rationale: The correct answer is all of the above. MRSA, CRE, and VRE are among the most concerning antibiotic-resistant bacteria in North America due to their prevalence and difficulty in treatment.
Why must clients,who will undergo diagnostic skin tests,avoid taking antihistamine or cold preparations for at least 48 to 72 hours before testing?
- A. Antihistamines may increase the potential for excessive bleeding.
- B. Antihistamines may aggravate the allergic reaction.
- C. Antihistamines may increase the potential for false-negative test results.
- D. Antihistamines may cause wheezing.
Correct Answer: C
Rationale: Antihistamines can suppress the allergic response,leading to false-negative results in skin tests.
Which of the following about Influenza virus is NOT correct
- A. It's an RNA virus
- B. In humans influenza infects the lung epithelial cells
- C. Release of newly formed virus from the infected cell is mediated by Hemagglutinin (HA)
- D. Tamiflu is a Neuraminidase (NA) inhibitor
Correct Answer: C
Rationale: The correct answer is C because the release of newly formed virus from the infected cell is actually mediated by Neuraminidase (NA), not Hemagglutinin (HA).
1. Influenza virus is indeed an RNA virus (Choice A).
2. In humans, influenza primarily infects lung epithelial cells (Choice B).
3. Hemagglutinin (HA) helps the virus enter host cells, while Neuraminidase (NA) helps release viral particles from infected cells (Choice C is incorrect).
4. Tamiflu is a Neuraminidase (NA) inhibitor, which prevents the release of viral particles, aiding in the treatment of influenza infections (Choice D).
The percentage of developing thymocytes undergoing negative selection in the thymus is close to
- A. 90%
- B. 50%
- C. 25%
- D. 10%
Correct Answer: A
Rationale: The correct answer is A (90%). Negative selection in the thymus eliminates self-reactive T cells. The process ensures self-tolerance. The majority of developing thymocytes are removed during negative selection, making it close to 90%. Choices B, C, and D are incorrect because negative selection eliminates a high percentage of thymocytes, not a lower percentage as indicated in those options.
Secondary lymphoid tissues are where:
- A. naïve lymphocytes become activated
- B. VDI gene rearrangement occurs
- C. Somatic hypermutation occurs
- D. Two of these options are correct
Correct Answer: D
Rationale: The correct answer is D because secondary lymphoid tissues are where both A and C processes occur. Naïve lymphocytes become activated in secondary lymphoid tissues through interactions with antigens, leading to their differentiation into effector cells. Somatic hypermutation also occurs in secondary lymphoid tissues, specifically in germinal centers of lymph nodes, leading to the generation of high-affinity antibodies. Option B, VDI gene rearrangement, does not occur in secondary lymphoid tissues; it is a process that happens in the primary lymphoid organs (bone marrow and thymus) during the development of lymphocytes. Thus, options A and C are correct, making the correct answer D.