Washington, April 13 : Making a significant advance towards new infertility treatments and a male contraceptive pill, scientists at Rensselaer Polytechnic Institute have identified key biochemical changes that put sperm "in the mood" for fertilization.

Dr. Mark D. Platt, a researcher from the Department of Chemistry and Chemical Biology, notes that sperm cannot fertilize an egg immediately after entering the female reproductive tract.

Washington, Apr 13 : Scientists at University of Oxford have found that mutations that hide HIV from immune system weaken the virus'' ability to replicate.

According to them, when HIV infects a cell, a complex of human immune proteins called HLA (short for human leukocyte antigen) alert killer T cells by displaying bits of the virus on the surface of the cell, in response to which the T-cells trigger immune attack.

They suggest that individuals who have certain types of HLA proteins control infection better than others.

Washington, April 13 : In what may hold significance for cancer treatment, scientists at Harvard Medical School have found that very dissimilar reactions take place even in genetically similar cells.

Research leader Peter Sorger, a professor of Systems Biology, has revealed that such discrepancies result from protein levels that vary from cell to cell, even among cells that are identical genetic twins.

London, April 13 : Just a drop of blood or a chunk of very tiny tissue is all that will be required to diagnose cancers and assess their response to treatment, if scientists have their way.

In a recently study, researchers at the Stanford University School of Medicine used a specialized machine that was capable of analysing whether individual cancer-associated proteins were present in the tiny samples, and even whether modifications of the proteins varied in response to cancer treatments.

London, Apr 13 : Contradicting the belief that women are born with a finite number of eggs, scientists have discovered stem cells in the ovaries of adult mice that seem to give rise to new eggs and healthy offspring.

If confirmed in humans, the above findings may revolutionise female reproduction by paving the way for women to delay child-rearing almost indefinitely.

It could also offer a new source of eggs for women who have been rendered infertile.

Sydney, April 13 : Drinking coffee could lower women's risk of suffering a stroke, a new study has suggested.

The study of 83,000 women, conducted over a 24-year period by Harvard Medical School and Harvard School of Public Health in Boston, revealed that women who drank five to seven cups of coffee a week were 12 per cent less likely to have a stroke than were those who downed just one cup a month.

However, German experts on stroke prevention in Berlin say that the benefit does not appear to come from caffeine, reports the Sydney Morning Herald.