A 4-year-old child with acute lymphoblastic leukemia is receiving high-dose methotrexate during interim maintenance. He receives ondansetron and арrepitant during his stay, which control his nausea and vomiting well. These medications work by inhibiting signaling in which part of the brain?
- A. Vestibular system
- B. Cerebral cortex
- C. Hypothalamus
- D. Vomiting center
Correct Answer: E
Rationale: The correct answer is D: Vomiting center. Ondansetron and aprepitant are antiemetic medications that work by inhibiting signaling in the vomiting center of the brain. The vomiting center is located in the medulla oblongata in the brainstem, which plays a crucial role in triggering the reflexes that lead to nausea and vomiting. By blocking signals in the vomiting center, these medications effectively prevent and control nausea and vomiting.
Incorrect choices:
A: The vestibular system is responsible for balance and spatial orientation, not for controlling nausea and vomiting.
B: The cerebral cortex is involved in higher brain functions such as thinking and decision-making, not in regulating nausea and vomiting.
C: The hypothalamus regulates various physiological processes like temperature regulation and hormone release, but it is not directly involved in controlling nausea and vomiting.
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A patient has an altered level of T and B cells. The nurse realizes that these cells are members of which cell type?
- A. Platelets
- B. Eosinophils
- C. Lymphocytes
- D. Red blood cells
Correct Answer: C
Rationale: The correct answer is C: Lymphocytes. T and B cells are subtypes of lymphocytes, which are crucial components of the immune system. T cells are involved in cell-mediated immunity, while B cells are responsible for producing antibodies. Platelets (A), eosinophils (B), and red blood cells (D) do not have the same functions or roles as T and B cells in the immune system. Platelets are involved in blood clotting, eosinophils are a type of white blood cell involved in allergic reactions, and red blood cells are responsible for oxygen transport.
A 2-month-old girl is found to have a small, hard mass on her scalp. The mass increases in size over the next 4 weeks. A biopsy is performed that confirms a diagnosis of embryonal rhabdomyosarcoma. You initiate chemotherapy with vincristine, dactinomycin, and cyclophosphamide. The child presents to clinic for day 1 of cycle 3 of chemotherapy, and the mass on her scalp is smaller. She is afebrile, absolute neutrophil count is 1,405 cells/mcL, platelet count is 154,000/mcL, and total bilirubin is 0.8 mg/dL. Her mother reports she looks very tired because her eyelids have been 'very droopy,' and she thinks she has a sore throat because her cry is hoarse. Her last bowel movement was 2 days ago. What is the most appropriate chemotherapy plan?
- A. Continue vincristine, dactinomycin, and cyclophosphamide at full dosage.
- B. Do not administer any chemotherapy; rhabdomyosarcoma is progressing and she needs different therapy.
- C. Administer dactinomycin and cyclophosphamide but hold the vincristine and reevaluate weekly. If the ptosis and hoarse cry resolve, vincristine can be resumed with a dose reduction and, if tolerated, re-escalated to the full dose in the future.
- D. Administer dactinomycin and cyclophosphamide but discontinue vincristine permanently.
Correct Answer: C
Rationale: The correct answer is C: Administer dactinomycin and cyclophosphamide but hold the vincristine and reevaluate weekly. If the ptosis and hoarse cry resolve, vincristine can be resumed with a dose reduction and, if tolerated, re-escalated to the full dose in the future.
Rationale:
1. Ptosis and hoarse cry are symptoms of vincristine-induced neurotoxicity.
2. Holding vincristine allows for resolution of these side effects.
3. Reevaluating weekly ensures close monitoring of symptoms.
4. If symptoms resolve, vincristine can be cautiously reintroduced with a dose reduction to prevent further neurotoxicity.
Summary:
A: Continuing all chemotherapy may worsen neurotoxicity.
B: Withholding all chemotherapy is not appropriate if two agents are effective.
D: Discontinuing vincristine permanently may limit treatment options.
You are consulted on a 4-year-old girl who is newly diagnosed with standard-risk pre-B acute lymphoblastic leukemia. After reviewing her previous complete blood examinations, you note she has had a platelet count ranging from 80,000 to 100,000 cells/mcL over the past 2 years. Her father mentions that he has also been told he has mild thrombocytopenia. You suspect the child may have a cancer predisposition syndrome. Which sample should you send for analysis, and which gene is most likely implicated?
- A. Skin fibroblasts to evaluate the RUNXI gene
- B. Skin fibroblasts to evaluate the ETV6 gene
- C. Buccal swab to evaluate the RUNXI gene
- D. Buccal swab to evaluate the ETV6 gene
Correct Answer: B
Rationale: The correct answer is B: Skin fibroblasts to evaluate the ETV6 gene. In individuals with familial thrombocytopenia and a history of malignancy, ETV6 gene mutations are often implicated. Sending skin fibroblasts for analysis allows for genetic testing to identify any ETV6 gene mutations that may be present. Skin fibroblasts are commonly used for genetic testing as they provide a stable and reliable source of DNA.
Choice A (Skin fibroblasts to evaluate the RUNXI gene) is incorrect because RUNXI gene mutations are not typically associated with familial thrombocytopenia and cancer predisposition syndromes. Choice C (Buccal swab to evaluate the RUNXI gene) is also incorrect for the same reason. Choice D (Buccal swab to evaluate the ETV6 gene) is incorrect because buccal swabs may not provide enough genetic material for comprehensive testing of the ETV6 gene, which is
Plat. Transfusion is not indicated in:
- A. aplastic an.
- B. uraemia with bleeding
- C. DIC
- D. immunogenic thrombocytopenia
Correct Answer: D
Rationale: The correct answer is D: immunogenic thrombocytopenia. Platelet transfusion is not indicated in immunogenic thrombocytopenia because it involves antibodies attacking platelets, which would render transfused platelets ineffective. Platelet transfusion is indicated in aplastic anemia (A) to increase platelet count, in uremia with bleeding (B) to replace dysfunctional platelets, and in DIC (C) to help manage severe bleeding. In summary, platelet transfusion is contraindicated in immunogenic thrombocytopenia due to ineffective platelet response.
Which of the following is not true in thrombasthenia:
- A. prolonged bleeding time
- B. normal plat .Count
- C. plat .Aggregation defect
- D. prolonged clotting time
Correct Answer: D
Rationale: In thrombasthenia, there is a deficiency or dysfunction of integrin αIIbβ3 (GPIIb/IIIa), leading to impaired platelet aggregation. Prolonged bleeding time (A) is seen due to defective platelet function. Platelet count (B) is typically normal as thrombasthenia does not affect platelet production. Platelet aggregation defect (C) is a characteristic feature of thrombasthenia. Prolonged clotting time (D) is not associated with thrombasthenia as it primarily affects platelet function, not the coagulation cascade. Hence, choice D is the correct answer.