Every cell contains a tiny clock called a telomere, which shortens each time the cell divides. Short telomeres are linked to a range of human diseases, including HIV, osteoporosis, heart disease and aging.

Shakespearean characters experiencing strong emotions are prone to fits, faints and even death, according to research published in this week’s Christmas issue of the BMJ.

Researchers have uncovered new evidence in mice that may explain how emotionally charged situations can leave such a powerful mark on our memories. Surges of the stress hormone norepinephrine (also known as noradrenaline) that often accompany strong emotions spark a series of molecular events that ultimately strengthen the connections between neurons, the team reports in the October 5, 2007, issue of the journal Cell, a publication of Cell Press.

Subjecting mice to repeated emotional stress, the kind we experience in everyday life, may contribute to the accumulation of neurofibrillary tangles, one of the hallmarks of Alzheimer's disease, report researchers at the Salk Institute for Biological Studies. While aging is still the greatest risk factor for Alzheimer's disease, a number of studies have pointed to stress as a contributing factor.

Scientists from Wake Forest University School of Medicine are the first to report that the stress hormone epinephrine causes changes in prostate and breast cancer cells that may make them resistant to cell death.