A 33-year-old woman is brought to the emergency department 30 minutes after being rescued from a fire in her apartment. She reports nausea, headache, and dizziness. Physical examination shows black discoloration of her oral mucosa. Pulse oximetry shows an oxygen saturation of 99% on room air. The substance most likely causing symptoms in this patient primarily produces toxicity by which of the following mechanisms?
AInhibition of mitochondrial complex V
BDegradation of 2,3-bisphosphoglycerate
COxidation of Fe2+
DRise in serum pH
ECompetitive binding to heme
A 72-year-old man has been recently diagnosed with stage 3 squamous cell carcinoma of the oral cavity. After the necessary laboratory workup, concurrent chemoradiation therapy has been planned. Radiation therapy is planned to take place over 7 weeks and he will receive radiation doses daily, Monday–Friday, in 2.0 Gy fractions. For concurrent chemotherapy, he will receive intravenous cisplatin at a dosage of 50 mg/m2 weekly for 7 weeks. Which of the following best explains the mechanism of action of the antineoplastic drug that the patient will receive?
AFree radical-mediated lipid peroxidation
BInhibition of polymerization of tubulin
CInhibition of topoisomerase 1
DInhibition of topoisomerase 2
EFormation of interstrand DNA cross-links
A healthy 34-year-old woman comes to the physician for advice on UV protection. She works as an archaeologist and is required to work outside for extended periods of time. She is concerned about premature skin aging. The physician recommends sun-protective clothing and sunscreen. In order to protect effectively against photoaging, the sunscreen should contain which of the following active ingredients?
AZinc oxide
BVitamin E
CPara-aminobenzoic acid
DTrimethoprim/sulfamethoxazole
ETrolamine salicylate
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