Circadian clocks regulate the timing of biological functions in almost all higher organisms. Anyone who has flown through several time zones knows the jet lag that can result when this timing is disrupted.

Now, new research by Cornell and Dartmouth researchers explains the biological mechanism behind how circadian clocks sense light through a process that transfers energy from light to chemical reactions in cells.

Colonoscopies are considered the gold standard for detecting colon cancer, the second leading cause of cancer deaths in the United States. Research presented today at Digestive Disease Week® 2007 (DDW®) discusses contributing factors that could prevent patients from getting optimal results from their colonoscopy, including age of the patient, location of the screening and proper technician training.

Scientists have refuted a longstanding theory of how HIV slowly depletes the body’s capacity to fight infection, in new research published today.

The researchers were looking at T helper cells, a class of white blood cells which recognise infection and co-ordinate the body’s immune defences. They are attacked by HIV, and their numbers gradually decline in HIV positive patients. It has long been a major puzzle why this process of depletion is so slow, often taking 10 years or more.

Wild relatives of plants such as the potato and the peanut are at risk of extinction, threatening a valuable source of genes that are necessary to boost the ability of cultivated crops to resist pests and tolerate drought, according to a new study released today by scientists of the Consultative Group on International Agricultural Research (CGIAR). The culprit is climate change, the researchers said.

It's a scenario straight out of Gray's Anatomy – a paramedic or doctor plops a mask over the face of a person struggling to breathe and begins dispensing pure oxygen.

Yet growing research suggests that inhaling straight oxygen can actually harm the brain. For the first time, a new UCLA brain-imaging study reveals why. The findings fly in the face of national guidelines for medical practice and recommend a new approach adding carbon dioxide to the gas mix to preserve brain function in patients.

Applying topical retinol to the skin appears to improve the wrinkles associated with natural aging and may help to promote the production of skin-building compounds, according to a report in the May issue of Archives of Dermatology.

The wrinkles and brown spots associated with aging appear first and most prominently on skin exposed to the sun, according to background information in the article.