Nokea
The physician plans to prescribe trastuzumab (Herceptin) for the patient with breast cancer. What testing will the physician order before prescribing this medication?
- A. HER2 protein levels
- B. BRCA2 gene mutation
- C. BRCA1 gene mutation
- D. Stage II cancer identification
Correct Answer: A
Rationale: Trastuzumab targets HER2-positive breast cancers, so HER2 protein level testing is essential to determine eligibility.
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Which of the following is correct with respect to measles:
- A. Outbreaks of the disease have recently occurred in developed countries as a consequence of decreased vaccination rates
- B. The disease has been eradicated globally
- C. There is no effective vaccine for this disease
- D. The disease is now easily treated and has no known long-term effects
Correct Answer: A
Rationale: Rationale for Choice A: Outbreaks of measles in developed countries are due to decreased vaccination rates, leading to lower herd immunity. This is supported by data showing increasing cases in countries with vaccine hesitancy. Other choices are incorrect because B is false - measles has not been eradicated globally, C is false - there is an effective vaccine for measles, and D is false - measles can lead to severe complications and long-term effects, especially in unvaccinated individuals.
What is NOT true about Shigella?
- A. Causes a form of bloody diarrhea
- B. It is a motile species possessing a flagellum
- C. It exploits specialized intestinal cells, called M cells, to infect the host
- D. It can travel from cell to cell, propelled by actin comets
Correct Answer: B
Rationale: The correct answer is B because Shigella is a non-motile species and does not possess a flagellum. Shigella relies on non-flagellar mechanisms for its movement within host cells. Choice A is true as Shigella causes bloody diarrhea. Choice C is also true as Shigella exploits M cells to infect the host. Choice D is true as Shigella can move from cell to cell using actin comets. In summary, choice B is incorrect because Shigella does not have a flagellum, while choices A, C, and D are all true characteristics of Shigella.
The major histocompatibility complex was given its name because the genes in this complex influence:
- A. T cell receptor gene rearrangement
- B. Acceptance or rejection of transplanted organs and cells
- C. Polarization of T helper cells
- D. The ratio of CD4+ and CD8+ T cells in an individual
Correct Answer: B
Rationale: The correct answer is B because the major histocompatibility complex (MHC) plays a crucial role in the immune system by determining whether transplanted organs or cells will be accepted or rejected. MHC molecules present antigens to T cells, which then trigger an immune response leading to acceptance or rejection. Choice A is incorrect because T cell receptor gene rearrangement is not directly influenced by the MHC. Choice C is incorrect as MHC does not directly polarize T helper cells. Choice D is incorrect because MHC does not directly regulate the ratio of CD4+ and CD8+ T cells in an individual.
Mature naïve T cells that leave the thymus
- A. Are all tolerant to self-antigens because all self-reactive developing T cells have been killed in the thymus
- B. Might include some self-reactive T cells that have not been tolerized against a specific Ag
- C. Go first to LN where they acquire the ability to recognize antigen presented by MHC
- D. Go first to LN to be tested for self-reactivity
Correct Answer: B
Rationale: The correct answer is B because mature naïve T cells that leave the thymus can include self-reactive T cells that have not been tolerized against a specific antigen. This is because the process of negative selection in the thymus eliminates most self-reactive T cells but does not catch all of them. Some self-reactive T cells may escape negative selection and circulate as mature naïve T cells. Therefore, it is possible for mature naïve T cells leaving the thymus to include self-reactive T cells that have not been tolerized against a specific antigen.
Choices:
A: This is incorrect because although negative selection in the thymus eliminates most self-reactive T cells, it does not catch all of them, so some self-reactive T cells may still be present in the mature naïve T cell population.
C: This is incorrect because mature naïve T cells already have the ability to recognize antigens presented by MHC, which is developed in the th
Which of the following is NOT a common condition associated with Type I hypersensitivity?
- A. Asthma
- B. Food allergies
- C. Anaphylaxis
- D. Systemic lupus erythematosus (SLE)
Correct Answer: D
Rationale: The correct answer is D: Systemic lupus erythematosus (SLE). Type I hypersensitivity involves IgE-mediated reactions to allergens, leading to immediate responses like asthma, food allergies, and anaphylaxis. SLE is an autoimmune disease involving immune complexes and not IgE antibodies. Therefore, SLE is not directly associated with Type I hypersensitivity. Asthma, food allergies, and anaphylaxis are all examples of Type I hypersensitivity reactions due to IgE-mediated mechanisms.