The constitutive COX-2 isoform tends to be homeostatic in function, while COX-1 is induced during inflammation and tends to facilitate the inflammatory response. The consideration is:

Correct Answer: B

Rationale: The correct answer is B: FALSE. COX-1 is constitutively expressed and involved in homeostatic functions, while COX-2 is inducible during inflammation to facilitate the inflammatory response. COX-1 is responsible for maintaining normal physiological functions, such as protecting the stomach lining and regulating blood flow, while COX-2 is primarily involved in producing prostaglandins during inflammation. Therefore, COX-1 is not induced during inflammation, and COX-2 is not homeostatic. Choice A is incorrect because COX-1, not COX-2, is homeostatic. Choice C is incorrect because there is a clear distinction between the functions of COX-1 and COX-2. Choice D is incorrect because not all options are correct; only option B is accurate based on the roles of COX-1 and COX-2 in the body.

Correct Answer: D

Rationale: Step-by-step rationale for why D (Pellagra) is correct: 1. Dermatitis: Pellagra is characterized by skin rashes due to niacin deficiency. 2. Diarrhoea: Niacin deficiency in Pellagra affects the digestive system, leading to diarrhea. 3. Dementia: Niacin deficiency affects the brain, causing neurological symptoms like dementia. Summary of why other choices are incorrect: A: Dry beriberi is caused by thiamine (B1) deficiency, not niacin. B: Pyridoxine deficiency (vitamin B6) does not typically present with dermatitis, diarrhea, or dementia. C: Scurvy is caused by vitamin C deficiency and is characterized by bleeding gums, weakness, and fatigue, not the symptoms mentioned in the question.

Correct Answer: C

Rationale: The correct answer is C. Gemfibrozil (Lopid) has not been shown to reduce mortality associated with heart disease. This statement is false as fibric acid derivatives, including gemfibrozil, primarily work by lowering triglycerides and increasing HDL cholesterol levels, which may help in reducing the risk of heart disease but not mortality directly. Choices A, B, and D are all true statements about fibric acid derivatives. A: Clofibrate is indeed used for Type III hyperlipidemia. B: Gemfibrozil increases HDL cholesterol and lowers LDL cholesterol. D: Gemfibrozil is generally well tolerated with common side effects being gastrointestinal upset and myopathy.

Correct Answer: B

Rationale: The correct answer is B: Metastatic calcifications. Vitamin D3 can lead to hypercalcemia, causing calcium to deposit in soft tissues like blood vessels and kidneys, leading to metastatic calcifications. Choice A is incorrect because vitamin D deficiency, not excess, causes defective bone mineralization. Choice C is incorrect as vitamin D toxicity primarily affects calcium levels, not the liver. Choice D is incorrect as nephrolithiasis is more commonly associated with excess intake of calcium supplements, not vitamin D3.

Correct Answer: B

Rationale: Step 1: Plicamycin inhibits RNA synthesis in cancer cells, leading to myelosuppression. Step 2: Myelosuppression results in decreased production of blood cells, causing anemia, thrombocytopenia, and neutropenia. Step 3: Diarrhea is not a common adverse effect of plicamycin. Step 4: Nephrolithiasis and metastatic calcifications are not directly associated with plicamycin use.