Why circumcision may minimise HIV risk
Circumcision reduces a man’s risk of acquiring and transmitting HIV and other sexually transmitted diseases,and now researchers have found a possible explanation: the procedure reduces the quantity and diversity of bacteria at the head of the penis.
Researchers in Uganda studied 79 men randomly assigned to circumcision and 77 who remained uncircumcised,controlling for age,number of sexual partners and other factors. After a year,the bacterial load had decreased in both groups,possibly because being in a study spurred behaviour changes. But the decrease was significantly larger in those who were circumcised.
Diversity of bacteria also decreased more in the circumcised men than in the uncircumcised,and almost all of the bacteria that decreased were anaerobic the kind that do not survive when exposed to oxygen at the exposed tip of the penis.
“Were not trying to prove that everyone should be circumcised,” said the senior author,Lance B Price,a professor of occupational and environmental health at George Washington University. NYT
Mental workouts add to brain power A review of the best evidence for interventions to prevent declining brain power finds that only one mental exercise consistently makes a difference.
The analysis of clinical trial results for assorted drugs,supplements and activities still cant say,however,whether the brain training programmes that do seem to sharpen mental function also improve peoples daily lives or lower their risk of developing dementia.
“All we know is you will do better on certain (cognitive) tests. Whether that delays dementia remains to be seen,” said Dr Raza Naqvi,the studys lead author and a researcher at the University of Toronto.
To see whether any approach fits that bill,or at least seems promising,Naqvi and his colleagues gathered results from all the randomized controlled trials they could find comparing the mental functioning of adults given a particular treatment to others who received no intervention.
Among drugs,hormone therapy,physical exercise and mental training,it was found that only the last yielded positive results every time.