A 54-year-old man with tuberculosis is maintained on a multidrug regimen including cycloserine. He complains of intermittent chest pressure and dyspnea but this does not limit his daily activities. On a cellular level, which of the following amino acids is blocked by this agent?

A 54-year-old man with tuberculosis is maintained on a multidrug regimen including cycloserine. He complains of intermittent chest pressure and dyspnea but this does not limit his daily activities. On a cellular level, which of the following amino acids is blocked by this agent?

A 45-year-old woman complains of facial wrinkles and lines. She heard of a drug for wrinkles from a friend that is a bacterial toxin and works by paralyzing skeletal muscles. What is the mechanism of action of this drug?

A 29-year-old man with recurrent herpes viral infections of the scrotum and penile shaft presents to his primary care physician because the medication is not working for him. He takes oral acyclovir for these outbreaks. Physical examination reveals active genitourinary herpes disease. What is the most likely explanation for the resistance to this medication?

Five patients with cancer and/or inflammatory disease are being considered for treatment with single agent methotrexate therapy intravenously. Which of the following patients would be expected to have the greatest objective clinical response to therapy?

A 42-year-old woman with bilateral metastatic breast cancer undergoes surgery followed by radiation and a cycle of chemotherapy. PET scan still reveals the presence of metastatic disease. She undergoes therapy with a novel chemotherapy agent capecitabine. This medication works through inhibition of which of the following?