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Fish offer hope for blind

The ability of a small tropical fish to regenerate damaged retinas could lead to an experimental treatment for blindness within five years. 'Our findings have enormous potential,' says Astrid Limb of University College London. Unlike mammals, zebrafish have an abundant supply of adult stem cells that they use to regenerate their retinas, Reuters reports. The British researchers have been able to easily grow the cells in the laboratory, and have successfully tested them on rats with diseased retinas. They hope to inject them into people's eyes to treat such diseases as macular degeneration, glaucoma and diabetes-related blindness.

Jog and java help ward off skin cancer

Combining exercise and coffee (not necessarily at the same time) may significantly increase protection from skin cancer, Rutgers University researchers have found in tests on mice. 'We think this will extrapolate to humans,' says team leader Allan Connery. When cells exposed to ultraviolet-B radiation become precancerous, they're programmed to self-destruct - a process called apoptosis. Failure to do so can lead to cancer developing and spreading. Mice that drank caffeine had a 95 per cent increase in apoptosis in damaged cells, AP reports. Those that exercised had a 120 per cent increase; and those that did both had a 400 per cent increase.

Coffee reduces colon cancer risk

Meanwhile, Japanese researchers have found that drinking three or more cups of coffee a day may halve the risk of colon cancer in women - but not in men. The 12-year study of more than 96,000 people aged between 40 and 69 found no beneficial link between drinking green tea and colon cancer, Reuters reports. National Cancer Centre researchers aren't sure why coffee seems to benefit women: caffeine may stimulate the working of the colon, or the effect may be due to coffee's antioxidant properties.

Weighing up the cost of friendship

Obesity is socially contagious, a landmark three-decade Harvard University study of more than 12,000 people has found - as is being thin. 'This reinforces the idea that because people are interconnected, their health is interconnected,' says team leader Nicholas Christakis. For example, a person's odds of becoming obese increase by 57 per cent if they have a friend who became obese, healthday.com reports. If an adult sibling becomes obese, the chance that the other will also become obese increases by 40 per cent. And for spouses, the chance rises to 37 per cent.

Spliff the difference

Smoking a single marijuana joint obstructs the flow of air as much as five tobacco cigarettes, researchers at the New Zealand Medical Research Institute have found. But although long-term users can develop symptoms of asthma and bronchitis, and excessive lung inflation, they appear to be at no greater risk of emphysema than non-smokers, AP reports.

Handy signs from orangutans

Orangutans use a form of charades to communicate, giving clear hand signals and other gestures to indicate whether they've been understood. A small study by researchers at University of St Andrews, Scotland, has found that orangutans not only express what they want using gestures but give feedback depending on the response, healthday.com reports. 'You can easily work out whether the orangutan thinks it has been understood,' the researcher say.

Schizophrenic squeaks

Researchers at Johns Hopkins University have created a schizophrenic mouse - which will allow testing of new drugs and treatments before they are used on humans. The genetically engineered schizophrenic mice will also enable scientists to track the progression of the disease, AFP reports. Previously, researchers could only induce schizophrenic symptoms, such as delusions, mood changes and paranoia, by administering drugs.

Sex feels good? Who knew?

After five years' research of almost 240 reasons why people have sex, University of Texas researchers have discovered that most of the time they do it because 'it feels good'. Among the key findings of the study of almost 2,000 people aged 17 to 52 were that lust beats love (the No1 reason for having sex was being attracted to the other person) and that, contrary to gender stereotypes, men and women do it for much the same reasons (20 of the top 25 were the same for both sexes), AP reports.

Jason Sankey is a tennis professional