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HIV Cocaine Link and ?Missing Link?

Cocaine may not only be associated with HIV infections because it causes people to act recklessly and have unsafe sex?it may also help the HIV virus spread faster through the body, killing off more immune cells and reproducing 200 times faster than usual.

?Cocaine not only influences risky behaviors, it also has a direct and profound effect on the AIDS virus,? says Dr. Gayle Baldwin, an AIDS researcher at UCLA. The spread of the HIV virus and its effects on immune cells known as CD4 T-cells are directly related to how sick a person becomes with HIV infection.

Baldwin already knew that people who use drugs are more likely to become infected with HIV. ?There were some studies done quite some time ago that suggested a correlation between cocaine use and the progression of disease in HIV-positive individuals,? she says. What was puzzling was why this held true for cocaine, which is not usually injected. The usual way that drug users get HIV is through sharing needles, so it was assumed this is because cocaine, especially crack, encourages unsafe sexual behavior. But she also knew that cocaine can affect the immune system.

Baldwin and her colleagues tested specially bred mice that are infected with the human AIDS virus. Half the mice got daily injections of liquid cocaine and half got salt water. They tested the mice 10 days later. ?We saw a 200-fold increase in AIDS viral load in the blood of the animals injected with cocaine compared to those that received the placebo,? Baldwin says. ?In only two weeks, the drug radically stimulated the production and spread of HIV.?

Baldwin also found out how many CD4 cells had been killed. ?The cocaine increased HIV?s efficiency so dramatically that it nearly wiped out the CD4 T-cells. We found nine times fewer CD4 T-cells in the cocaine-treated mice than in the animals that received the placebo,? she say. ?This means that the cocaine produced a spectacular double outcome. Not only did the drug double the number of HIV-infected cells, it produced a nine-fold plunge in the number of T-cells that fight off the virus.?

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Researchers have discovered genetic mutations in the children of HIV-positive mothers who were treated with drugs aimed at preventing the transmission of the virus to their infants. ?We have confirmed that the risk is more than theoretical,? says Vernon Walker, formerly at the New York State Department of Health. These types of drugs are called nucleoside reverse transcriptase inhibitors (NRTI). Third-world countries with large populations of AIDS-infected women are trying to obtain these drugs for pregnant women.

No evidence of harm has been found in any children as yet but rat studies by Walker in 2001 showed that children exposed to NRTIs as embryos were healthy until middle age, when NRTI-induced cancers began to develop.

The oldest children treated with NRTIs are now just seven years old. ?We will have to wait decades to see what happens,? says Walker. He adds that different combinations of NRTIs have different effects and hopes that further work will reveal the sets of drugs with the lowest risks.

The benefits of taking the NRTIs may still outweigh the risk. But Rochelle Diamond, of the National Organization of Lesbian and Gay Scientists says, ?Most of the talk has been about HIV-positive women who [accidentally] become pregnant. But HIV-positive people are now making a conscious decision to have a child [because of NRTI drugs]?that?s a different risk-versus-benefit question.?

NRTIs work by inserting themselves into the DNA of the HIV virus, preventing the production of a specific enzyme needed for the replication of the virus. But the drug can also insert itself into the genes of the patient and the unborn child.

Walker's new study compared 71 babies who had been exposed to the drugs in the womb. He analyzed umbilical cord lymphocyte cells for two reporter genes and found significantly higher genotoxic and mutagenic effects in the exposed babies.

NRTIs have been successful in reducing transmission of HIV to babies, lowering the rate from about 25 per cent to eight per cent, and in some cases just two percent. Walker contrasts this success with the probably low rate of any cancer caused by the mutations and says, ?I don?t think the cancers that you might see in these children in their forties or fifties will ever reach the numbers of the children you are preventing getting a fatal disease.?

But the previous medical experience warns that long-term side effects can be devastating. The drug DES was taken by women for 20 years until 1971 to reduce the miscarriages, but DES daughters were eventually found to have much higher rates of cervical cancer.

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As many as 1 million Americans are now living with HIV infections and about half are undiagnosed or untreated, according to the Centers for Disease Control and Prevention.

AIDS death rates in the U.S. have declined sharply because of successful therapies. As recently as 1996, the last year before new combinations of drugs began prolonging survival, there were 38,025 AIDS deaths reported. By 2000, 15,245 people died. At the same time, however, the number of Americans becoming newly infected hasn?t gone down but has remained steady at about 40,000 each year.

As a result, the number of people living with the virus that causes the disease is now increasing by about 25,000 a year, bringing the total number of people infected to an all-time high. The CDC thinks that about a quarter of those infected do not know they have the disease, which puts them at the highest risk for spreading the illness.

?A major part of what we are trying to do at CDC is to get people tested,? says Dr. Harold Jaffe, director of the CDC's National Center for HIV, Sexually Transmitted Diseases and Tuberculosis Prevention. ?The take-home message is that there are more people living with HIV than ever before, there are too many who are diagnosed too late, and there are an unacceptable number not receiving treatment and services.?

According to the latest figures on the course of the AIDS epidemic--estimates that have been revised over the years--about 400,000 to 450,000 Americans were infected with the disease in 1984. By 1986, the number had grown to 550,000 to 650,000. By 1992, the figure was 650,000 to 900,000.

Data from the 25 states that have extensive HIV and AIDS reporting shows that the total number of Americans living with HIV increased by about 25,000 a year from 1998 to 2000, bringing the total in 2000 to between 850,000 to 950,000, and the total is now nearing 900,000 to 1 million.

When AIDS victims do die, fewer are dying from such conditions as tuberculosis and pneumocystic pneumonia. A higher percentage are dying from liver and kidney disease, reports show. The shift in causes of death is probably due to several factors, says Dr. Mitchell I. Wolfe of the CDC. Some of the drugs used to treat HIV infections can produce kidney and liver damage, so at least some of the increase may be attributable to these complications. Also, because effective drug treatments mean people can live longer with AIDS than before, the average age of the population with AIDS is increasing, and both kidney and liver diseases are more common in the elderly.

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Scientists have discovered a new type of HIV-like virus in monkeys which they believe may provide the ?missing link? between the similar primate virus and the human form. The new simian immunodeficiency virus, called SIVgsn, has been found in 19 greater spot-nose monkeys in Cameroon.

SIVgsn is similar to HIV-1, a strain that causes Aids in humans, and also to a form of the virus that is found in chimpanzees. French researcher Eric Delaporte believes the new virus may help to explain the connection between SIV and HIV.

Chimpanzees eat greater spot-nose monkeys, and the research suggests that this is how they originally became infected with SIV. Unlike humans, monkeys are natural carriers of the virus and can have it without developing AIDS. However, the meat of the smaller monkey is also eaten by humans. HIV may have begun when some people became infected with SIVgsn, possibly by cutting themselves while preparing infected meat.

The French researchers found that SIVgsn contains a gene which controls the way it reproduces itself, and which gives it the potential to jump from monkeys to man. Dr. Delaporte says, ?The virus could therefore very well be transmitted to humans, or other monkeys, to create either new strains of divergent HIV viruses, or it could combine with existing viruses thus complicating the virological specter of HIV.?

John Godwin, head of policy and advocacy, National AIDS Trust, says, ?We have known for some years now that in all likelihood HIV jumped the species barrier between monkeys and humans sometime last century.?

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