In a randomized, controlled trial in Thailand, pregnant women infected with the human immunodeficiency virus (HIV) type 1 received zidovudine treatment plus a single dose of either nevirapine or placebo. The rate of transmission of HIV to newborns was 2.8 percent in the nevirapine group and 6.3 percent in the placebo group. The rate was 1.9 percent in a group in which a single dose of nevirapine was also administered to the infants shortly after delivery.

When added to zidovudine prophylaxis, a single dose of nevirapine is highly effective in reducing mother-to-infant transmission of HIV.

After participating in a placebo-controlled trial of antiviral regimens to reduce mother-to-child transmission of the human immunodeficiency virus (HIV) in Thailand, some of the women began taking a nevirapine-containing regimen. After six months, the rate of viral suppression was lower among the mothers who had received intrapartum nevirapine than among those who had not received it (49 percent vs. 68 percent, P=0.03).

These observational data suggest that intrapartum exposure to a single dose of nevirapine may lead to selection for resistance mutations that can adversely affect a woman's subsequent antiviral treatment.

Despite knowledge that women with hypothyroidism should increase their usual levothyroxine dose during pregnancy, biochemical hypothyroidism still occurs. This study found that the levothyroxine requirement increased by a mean of 48 percent during the first half of pregnancy and that monitoring and dose adjustments were required until delivery.

Given the importance of maternal euthyroidism for normal fetal cognitive development, women with hypothyroidism should increase their levothyroxine dose by approximately 30 percent once pregnancy is confirmed.

Using combined immunohistochemical and fluorescence in situ hybridization techniques, these investigators found chromosomal abnormalities typical of B-cell lymphomas not only in the lymphoma cells but also in the microvascular endothelial cells in the lymphoma.

These findings link lymphoma cells to angiogenesis. The discovery of how this link forms will be a major step forward in understanding the origins and growth of lymphomas.

A 52-year-old woman with no history of venous thromboembolism presents with a four-day history of discomfort in her left calf. Proximal deep-vein thrombosis is diagnosed by compression ultrasonography. How should her case be managed?

Arterial thrombosis is an important complication of systemic lupus erythematosus. These investigators found that the presence of variant alleles of mannose-binding lectin (MBL), a serum protein involved in innate immune defense, increases the risk of arterial thrombosis, especially myocardial infarction, in patients with lupus. The results suggest that the common allelic forms of mannose-binding lectin may have a role in protecting against arterial thrombotic events.

A woman sought medical attention because of chest pain and shortness of breath. Physical examination and echocardiographic studies showed evidence of a pericardial effusion and cardiac tamponade. She was admitted to the hospital, and the effusion was drained, yielding fluid that was negative on culture and cytologic analysis. She had traveled to Kenya; a tuberculin skin test five months after the trip had been negative, but a test during hospitalization was positive.