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Brainstorming

some brain tumours may be caused by a common virus, indicates a new study conducted by researchers of the Philadelphia-based Temple University. During their study, they analysed a particular type of tumour called medulloblastoma. The tumour is the most common type of malignancy found in the brains of children across the globe. The researchers traced proteins that are produced by the jc virus (jcv) in numerous samples of the tumour.

Though the virus infects at least 70 per cent children worldwide very early in life, it lies dormant in most cases. The virus is already known to cause a fatal disease of the nerves called progressive multifocal leukoencephalopathy (pml). "The virus was detected in a good number of the brain tumours we sampled,' said Kamel Khalili, researcher at the university. Two types of protein produced by jcv were found by the researchers. They are known as agnoprotein and T antigen.

Evidence of agnoprotein was found in 69 per cent of 16 medulloblastoma samples, while evidence of T antigen was found in 65 per cent of 20 medulloblastoma samples. T antigen causes tumours in particular parts by blocking the action of other proteins that suppress developing tumours. The role of agnoprotein in the development of brain tumours remains unknown. Researchers have concluded from their observations that jcv might also be stimulating the rapid and uncontrolled cell growth, which is typical of cancer ( www.bbc.co.uk , February 19, 2002).

However, they cautioned by saying that this does not mean that every single brain tumour is caused by the jcv. Even Howard Fine of the us National Cancer Institute has criticised the findings. According to him, the presence of the protein in tumour cells may simply be a sign of an old infection not directly linked to the development of cancer.

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