A 34-year-old man with a history of recurrent tuberculosis on a multidrug regimen, including isoniazid. He presents to his primary care physician complaining of paresthesias of his hands and feet. What is the most likely explanation for this finding?

A 34-year-old man with a history of recurrent tuberculosis on a multidrug regimen, including isoniazid. He presents to his primary care physician complaining of paresthesias of his hands and feet. What is the most likely explanation for this finding?

A 4-year-old boy is hospitalized on the pediatric service with cough, runny nose, and chest pressure. Concern for respiratory syncytial virus is brought up by the treating physician. Treatment with zanamivir is undertaken. Which of the following underlying conditions can worsen bronchospasm in this patient?

A 52-year-old female presents with facial wrinkling that has not been satisfactorily treated with creams. She requests information on botulinum toxin A at an acquaintance’s recommendation. Botulinum toxin’s mechanism of action is most similar to which other bacterial toxin?

A 45-year-old man with HIV disease and herpesvirus has begun on therapy with foscarnet. The medication is administered intravenously. If serum electrolytes are drawn on this patient after 1 week of therapy, which of the following laboratory values would be expected to be abnormal?

A 43-year-old man with leukemia is hospitalized for treatment after his prior chemotherapeutic regimen failed to produce remission. Bone marrow biopsy is repeated and indicates the presence of hairy cell leukemia. Treatment with fludarabine has begun. This agent likely works in which of the following ways?