Penis toughener discovered

RESEARCHERS believe the spread of HIV could be reduced with a world-first discovery at the University of Melbourne. The study, to be published today in PLoS One medical journal, reveals that the application of oestrogen to the human penis increased the thickness of the natural keratin layer on the skin, which could prevent HIV from infecting the male.

Dr Andrew Pask, of the Department of Zoology at the university, made the discovery after analysing the tissue samples from 12 foreskins. "This suggested that oestrogen could induce a thickening of the keratin layer of the foreskin epidermis in the same way as it acts in the vagina," Dr Pask said. Topical oestrogen was applied to the human foreskin for a two-week trial to confirm its effect. This resulted in a rapid and substantial increase in keratin thickness.

Professor Roger Short, of the university's faculty of medicine, said today: "We have found a new avenue to possibly prevent HIV infection of the penis. "In countries where circumcision is not religiously or culturally accepted, oestrogen treatments to the penis could be very effective in reducing the spread of the disease."

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Cannabis 'shrinks brain volume'

HEAVY marijuana use over many years appears to shrink those parts of the brain that control emotion and memory, an Australian study has shown. Brain scans on 15 men who smoked at least five joints a day for more than a decade show for the first time that they have structural brain abnormalities not seen in non-smokers.

The researchers from the University of Melbourne say their findings should settle the historic controversy over the long-term effects of cannabis use with solid proof of the damage it causes. "These findings challenge the widespread perception of cannabis as having limited or no consequences on the brain," said study leader Dr Murat Yucel, a clinical neuropsychologist at the Melbourne Neuropsychiatry Centre. "Although modest use may not lead to significant neurotoxic effects, these results suggest that heavy daily use might indeed be toxic to human brain tissue."

The study, published in the US journal Archives of General Psychiatry, showed two important areas of the brain were smaller in long-term smokers. The hippocampus, thought to regulate emotion and memory, was 12 per cent smaller in volume and the amygdala, involved with fear and aggression, was reduced by seven per cent. The smokers also were more likely to show mild signs of psychiatric disorders, but not enough to be formally diagnosed with one, Dr Yucel said. The men also performed "significantly worse" in a memory test that involved trying to recall a list of 15 words.

He admitted the findings did not necessarily prove marijuana was responsible for the difference in brain volume but the findings strongly suggest this was the cause. If this was the case, this indicated everyone was vulnerable to potential changes in the brain, some memory problems and psychiatric symptoms if they used heavily enough and for long enough, the researchers said.

The study involved men who were around the age of 40 and who had not taken other illicit drugs more than 10 times.

Another recent research review from the University of NSW showed that cannabis smokers had a 40 per cent increased risk of developing schizophrenia, and smoking daily drives the risk up two-fold. Other studies have linked the habit to gum disease and lung cancer. Statistics show a third of Australians have smoked at least once in their life, with about 300,000 using daily.

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