This study examined exposure to traffic in urban areas as a potential trigger of myocardial infarction. A significant association was found between exposure to traffic and the onset of a myocardial infarction one hour later, whether the time spent in traffic was in a car, on a form of public transportation, or on a bicycle.

The explanation for the finding is uncertain, but it is probably related to the detrimental effects of air pollution in heavily traveled areas — although mental stress experienced in conditions of dense traffic could also have a role.

This randomized trial compared preoperative with postoperative chemoradiotherapy for locally advanced rectal cancer. Overall survival was similar in the two groups, but patients assigned to preoperative chemoradiotherapy had lower rates of local recurrence and fewer long-term toxic effects than patients in the postoperative group.

At five years, overall survival among patients with locally advanced rectal cancer is about 75 percent. Advances in the management of this disease can evolve from earlier diagnosis, improvements in surgical technique, and more effective chemotherapy.

Even with antituberculosis therapy, tuberculous meningitis causes death or severe disability in more than half of affected adults. In this double-blind, placebo-controlled trial, conducted in Vietnam, dexamethasone treatment was associated with a reduced risk of death as compared with placebo (31.8 percent vs. 41.3 percent).

This major study establishes that adjunctive corticosteroid treatment improves survival in patients over 14 years of age who have tuberculous meningitis.

This study shows that three polymorphisms of the prostanoid prostaglandin D receptor gene (PTGDR) are associated with protection against asthma. Each of the polymorphisms affects the binding of a transcription factor that, in turn, influences the expression of PTGDR. Inheritance of the three polymorphisms that result in a low level of expression of PTGDR is associated with protection against asthma in European-American and African-American populations.

A 42-year-old woman presents with a palpable mass on the left side of her neck. She has no neck pain and no symptoms of thyroid dysfunction. Physical examination reveals a solitary, mobile thyroid nodule, 2 cm by 3 cm, without lymphadenopathy. The patient has no family history of thyroid disease and no history of external irradiation. Which investigations should be performed? Assuming that the nodule is benign, which, if any, treatment should be recommended?

RNA interference (RNAi) involves the use of easily generated RNA fragments to down-regulate gene expression in a highly specific manner. Since its discovery, about seven years ago, the method has quickly evolved and is now a routine application in many molecular laboratories. Recent success in treating animal models of disease indicates that RNAi also has the potential to treat human disease.

A 68-year-old man was found to have a large retroperitoneal mass on routine physical examination. Biopsy disclosed a gastrointestinal stromal tumor. After four months, the tumor had increased in size, although the patient remained asymptomatic. The discussants review recent advances in diagnosis and treatment of this type of tumor as they apply to the patient.