Women who have breast cancer due to a BRCA1 gene mutation are usually:

Correct Answer: D

Rationale: Women with breast cancer due to a BRCA1 gene mutation commonly have a triple-negative breast cancer subtype, which means they are negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2). This subtype tends to be more aggressive and harder to treat. Choice A is incorrect as they are typically negative for HER2. Choice B is incorrect because they are usually negative for estrogen receptor. Choice C is incorrect as they are usually negative for progesterone receptor and HER2.

Correct Answer: D

Rationale: Colon cancer is more likely associated with blood in stool due to the presence of bleeding from the tumor in the colon. Gastroesophageal reflux (Choice A) typically presents with heartburn and regurgitation but not blood in stool. Crohn's disease (Choice B) can cause gastrointestinal symptoms, but bloody stools are more commonly associated with ulcerative colitis. Irritable bowel syndrome (Choice C) is characterized by abdominal pain, bloating, and changes in bowel habits, but it does not typically cause blood in stool. Therefore, the correct answer is D, Colon cancer.

Correct Answer: A

Rationale: The clinical findings of thin hair, exophthalmos (bulging eyes), hyperreflexia, and pretibial edema are classic manifestations of Graves disease, an autoimmune condition that results in hyperthyroidism. Choice B is incorrect because weight gain and constipation are more indicative of hypothyroidism, not hyperthyroidism seen in Graves disease. Choice C is incorrect as the symptoms described are more characteristic of hypothyroidism, not hyperthyroidism. Choice D is also incorrect as the symptoms listed are not consistent with Graves disease but rather suggest hypothyroidism.

Correct Answer: B

Rationale: The correct answer is B: Underexcretion of uric acid. In gouty arthritis, the crystallization within the synovial fluid of the affected joint is caused by the underexcretion of uric acid, leading to the accumulation and subsequent crystallization of urate crystals. Choice A, destruction of proteoglycans, is incorrect as it is not directly related to the crystallization process in gouty arthritis. Choice C, overexcretion of uric acid, is incorrect because gout is primarily associated with underexcretion or decreased excretion of uric acid rather than overexcretion. Choice D, increased absorption of uric acid, is also incorrect as the primary issue in gouty arthritis is the body's inability to properly eliminate uric acid.

Correct Answer: B

Rationale: In this scenario, the rising lactic acid levels in a 65-year-old man after a coronary artery bypass graft could indicate bowel ischemia. Bowel ischemia can lead to anaerobic metabolism, causing an increase in lactic acid levels. Excessive sedation may cause respiratory depression but would not directly lead to rising lactic acid levels. Excessive volume infusion in the operating room might cause fluid overload but would not typically result in rising lactic acid levels. Mild hypothermia postoperatively could lead to shivering and increased oxygen consumption, but it is less likely to be the primary cause of rising lactic acid levels in this context.