Nokea
What chemical in poison ivy is responsible for triggering contact dermatitis?
- A. Histamine
- B. Urushiol oil
- C. Lipopolysaccharide (LPS)
- D. C3a
Correct Answer: B
Rationale: The correct answer is B: Urushiol oil. Urushiol oil is the allergen in poison ivy that triggers contact dermatitis. When urushiol oil comes into contact with the skin, it can cause an allergic reaction leading to redness, itching, and inflammation. Histamine (choice A) is a compound released by the body in response to allergens but is not the specific chemical in poison ivy. Lipopolysaccharide (LPS) (choice C) is a component of the outer membrane of certain bacteria and not present in poison ivy. C3a (choice D) is a complement protein involved in the immune response but not related to poison ivy dermatitis.
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In each of the following situations identify which option has the highest risk for human immunodeficiency virus (HIV) transmission?
- A. Transmission to women OR to men during sexual intercourse
- B. Hollow-bore needle used for vascular access OR used for IM injection
- C. First 2 to 6 months of infection OR 1 year after infection
- D. Perinatal transmission from HIV-infected mothers taking antiretroviral therapy OR HIV-infected mothers using no therapy
Correct Answer: C
Rationale: During the acute phase of HIV infection (first 2-6 months), viral loads are extremely high, increasing the likelihood of transmission.
What outcome would you least expect if the amount of template in a PCR fell significantly below the optimal amount?
- A. non-specific amplification
- B. increased yield
- C. Allelic drop-out (some alleles fail to amplify)
- D. Longer targets amplify poorly or fail
Correct Answer: B
Rationale: The correct answer is B: increased yield. If the amount of template in a PCR falls significantly below the optimal amount, it would be expected to result in a decreased yield rather than an increased yield. The template is essential for DNA amplification in PCR, and a lower amount would lead to fewer copies being produced. Non-specific amplification (choice A) can occur if there is too much template or incorrect primer annealing. Allelic drop-out (choice C) is likely to happen if there is insufficient template present to amplify all alleles. Longer targets amplifying poorly or failing (choice D) is also a common outcome when template concentration is low. Therefore, the least expected outcome would be an increased yield as that goes against the principle of PCR amplification.
A patient had a complicated vaginal hysterectomy. The student nurse provided perineal care after the patient had a bowel movement. The student nurse tells the nurse there was a lot of light brown, smelly drainage seeping from the perianal area. What should the nurse suspect when assessing this patient?
- A. Dehiscence
- B. Hemorrhage
- C. Keloid formation
- D. Fistula formation
Correct Answer: D
Rationale: Fistula formation involves abnormal connections between organs or tissues, often caused by infection or trauma. Light brown, smelly drainage suggests communication between the bowel and skin, indicative of a fistula.
Signal 2 for T cell activation is
- A. Necessary for re-activation of memory T cells
- B. Required to develop tolerance to self-antigens
- C. Mediated by CD3
- D. Essential for the activation of naïve T cells
Correct Answer: D
Rationale: The correct answer is D because Signal 2 is essential for the activation of naïve T cells. Signal 1 provides the antigen recognition, while Signal 2, typically provided by co-stimulatory molecules, is required for full T cell activation. A is incorrect because Signal 2 is not specifically for memory T cell re-activation. B is incorrect because Signal 2 is not related to self-tolerance, which is typically maintained by regulatory T cells. C is incorrect because CD3 is a component of the T cell receptor complex, not the primary mediator of Signal 2.
Identify the incorrect statement in regard to immunoglobulins (Ig)
- A. Are made up of two identical light chains and two identical heavy chains
- B. Cannot recognize conformational antigens on viral particles
- C. Can recognize only exposed epitopes of pathogens
- D. Expressed early during B cell development on the membrane of B cell precursors (pre- B cells)
Correct Answer: B
Rationale: The correct answer is B because immunoglobulins can indeed recognize conformational antigens on viral particles. Immunoglobulins have variable regions that can bind to a wide range of antigen shapes. Choice A is correct as Ig structure consists of two light and two heavy chains. Choice C is incorrect as immunoglobulins can also bind to internal epitopes. Choice D is incorrect as Ig expression starts during the late B cell development stage.