SNIPPETS.

Protein CCR key to smallpox, AIDS

Operation Smallpox Zero was launched in India in 1975 and was certified globally eradicated on December 9, 1979. But relief over the first success story of modern medicine was short-lived.

The experts of the immunisation drive did not know that another virus, lurking in the African forests, was as keen for smallpox to clear out as they were. It came to light in the 1980s as HIV and is still counting its victims. The period that marked the eradication of smallpox and merged into the rapid spread of AIDS had caught Weinstein’s eye but he couldn’t ignore a protein called CCR, essential to both the viruses. “CCR5 and CXCR4 are two receptors on cell surfaces that help immune cells go to infection sites. HIV uses them to invade cells as a part of its life-cycle,” said Michael, geneticist from the University of California at Los Angeles. “Some European people have a mutated CCR5 gene which makes them HIV-resistant,” said Michael Bukrinsky, vice-chair of microbiology, immunology, tropical medicine at George Washington University in USA.

How does the study explain HIV-positive people who also received the smallpox vaccine?  “In our case, it is the innate immunity induced by the vaccine that conferred protection but it is short-lived usually. So it was exciting to see protection even a year later,” said Bukrinsky. Virologist T Jacob John, however, thinks the link made by the study is a mere speculation. The doctor from the the Christian Medical College in Vellore, said: “Imagine the smallpox vaccine continuing into the 1980s and thereafter, it would have been impossible to control the spreading of both the fatal diseases.”
Susmita Dey, Down to Earth Features

Proton four pc smaller than thought
For most of us, four per cent off around the waist would be a great triumph. Not so for the proton that anchors atoms and is the building block of all ordinary matter, of stars, planets and people. Physicists announced recently that a new experiment had shown that the proton is about four per cent smaller than they thought.

Such a big discrepancy, say the physicists, led by Randolf Pohl of the Max Planck Institute for Quantum Optics in Garching, Germany, could mean that the most accurate theory in the history of physics, quantum electrodynamics, which describes how light and matter interact, is in trouble.“What you have is a result that actually shocked us,” said Paul Rabinowitz, a chemist from Princeton University, who was a member of Pohl’s team. The results were published in Nature. Protons, of course, have not shrunk. They have been whatever size they are ever since they congealed out of a primordial soup of energy and even smaller particles – quarks and gluons – in the early moments of the Big Bang.
Determining how big they are, however, is both important to fundamental physics and extremely difficult.

Unable to calculate a radius directly from theory, physicists have measured protons in different ways. One is by scattering electrons off them. Another more accurate way is by spectroscopic measurements of the wavelength of the light emitted as electrons in the atom jump from one orbit to another and using quantum theory to compute the proton’s properties. Pohl and his colleagues created atoms in which the electron had been replaced by a muon, which is a sort of fat electron. Weighing 200 times more than an electron, the muon circles its proton more closely and thus gives a better reading of the proton size.
Dennis Overbye

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