Top stories in health and medicine this morning, March 12, 2012

This series is brought to you by MedPage Today.

1. ‘Superinfection’ with HIV Raises Questions. People who have repeated exposure to HIV can acquire different viral strains at different times, a phenomenon called “superinfection.”

2. Springing Ahead May Uncoil the Heart. When the clocks are moved ahead for daylight saving time, the disrupted circadian rhythm could result in a heart attack.

3. Cancer Survivors Face Major Health Risks. A growing population of cancer survivors faces an increased risk of radiation-related second malignancy and cardiovascular disease (CVD) for which little evidence-based clinical guidance has emerged.