Saturday, September 9, 2006 | Categories: Episodes
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Martian Gas Jets
As if there weren't already reason enough to visit Mars, Dr. Phil Christensen and his colleagues have found yet another amazing Martian feature that begs to be explored. For the past few years, scientists have been puzzled by strange dark spots that appear on Mars' southern ice cap each spring, as it starts to melt. Dr. Christensen is in charge of the THEMIS (Thermal Emission Imaging System) cameras aboard NASA's Mars Odyssey Orbiter, and is a professor of Geological Sciences at Arizona State University. He's found evidence that these dark spots are caused by violent jets of carbon dioxide (CO2) gas and sand bursting out of the ice cap. Dr. Christensen says sunlight passes through the CO2 ice, warming up the ground beneath it, and melting the ice cap from the ground up. This means the entire ice cap eventually rests on a cushion of high-pressure CO2 gas until -- ka-boom! -- the gas finds a weakness in the ice and blows a kilometre-high jet of sand and CO2 into the atmosphere. The sand falls back to the surface, forming the mysterious dark spots on the surface of the ice. Listen to this segment:
XVI International AIDS Conference: Prevention Science
Last August, Quirks & Quarks producer, Pat Senson attended the AIDS conference in Toronto, looking for the latest trends in preventing HIV transmission.
For most of the last 25 years, prevention has focused on the "ABCs" of prevention: Abstinence, Behaviour (being faithful) and Condom use. But, while partially successful, they haven't stemmed the tide of new infections, with an estimated 4 million new cases appearing last year. So researchers are looking for other, science-based solutions.
One of the closest to being introduced is male circumcision. Dr. Stephen Moses, from the University of Manitoba, is running a clinical trial to see whether circumcising men lowers their risk of catching HIV. If anecdotal data can be believed, it does; early observational studies in Africa showed that populations where men are routinely circumcised have a lower prevalence of HIV infection. His isn't the only trial. Dr. Maria Wawer, from Johns Hopkins University, is also running a trial, and expects results some time in the next year. A third trial showed a 60 per cent reduction of infection rates among circumcised men. According to Dr. Moses, if this result is reflected in the remaining two trials, circumcision could reduce overall infection of both men and women, by two thirds, if widely adopted.
Another very important development is the creation of microbicides. These are products that a women can apply vaginally before engaging in sexual activity, to prevent transmission of the virus. Dr. Zeta Rosenberg is the CEO of the International Partnership for Microbicides and says microbicides are critical in allowing women to protect themselves. All the existing methods of preventing HIV transmission are initiated by men, and microbicides would give some of the control to women. Various products are being tested. The first may reach the market by 2010.
A third major arm of protection research is pre-exposure prophylaxis (PreP). PreP involves giving healthy, but high-risk, individuals the same drugs used to treat HIV-infected people. In theory, this would prevent the virus from getting a foothold if the person is exposed. Currently, this approach is being tested in a number of clinical trials. Dr. Helene Gayle, President and CEO of CARE, is overseeing a number of these trials.
The "holy grail" of prevention is the successful creation of a protective vaccine. However, early work in this area has been only partially successful. Dr. Rafick-Pierre Sekaly, a professor at Université de Montréal, says we're only a few years away from a partially protective vaccine, but full protection will take much longer. He says the virus itself is what has made the research so complicated up until now, but we're getting much closer to finding a solution.
All these technical solutions to the spread of HIV are only half the battle, though. Dr. Christina Pimenta, the Executive Director of the Brazilian Interdisciplinary AIDS Association cautions that unless we address the issues of human, and especially women's rights in the developing world, we'll never beat AIDS.
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The official website for the XVI International AIDS conference
The International Partnership for Microbicides
Dr. Moses paper on circumcision and infection rates in Africa
A National Institutes of Health Q&A on circumcision and HIV
Dr. Wawer's trial in Uganda
The Global Campaign for Microbicides
WHO information page on microbicides
Audio and video clips from the Microbicides 2006 meetings
Reports on PreExposure Prophylaxis at AIDS 2006
Dr. Sekaly's homepage
The HIV Vaccine Trials Network
The International AIDS Vaccine Initiative
Women and AIDS
One of the dominant themes of this year's International AIDS Conference was the plight of women with HIV/AIDS. In the early years of the disease, women represented only a tiny fraction of those affected, but now they are becoming the main casualty of the global AIDS epidemic. By 2004, the number of women living with HIV around the world had skyrocketed to 20 million. If those rates of infection continue to rise, women will soon become the majority of people infected across the globe.
One of the people at the conference with a particular interest in the issue of women and HIV/AIDS was Dr. Ann Stewart. She is currently a resident in family medicine at the University of Toronto, and has noticed a significant increase in the number of female patients with HIV/AIDS, especially among recent immigrants. Dr. Stewart also happens to be a former Senior Producer of Quirks, who traded in her microphone several years ago for a stethoscope. So we sent Dr. Stewart to the International AIDS conference to investigate the issue for us. Here are some of the people she spoke to:
Esther Tharao, a researcher who works with the African and Caribbean Council on HIV/AIDS in Toronto, says many immigrant women who arrive in Canada with HIV/AIDS are isolated from their communities, and are afraid of telling anyone about their status.
Sherri Weiser, is a physician from the Centre for AIDS Prevention Studies at UCSF. She conducted a study on food insufficiency and HIV in Africa, and found that women are likely to engage in unsafe sex practises when they are forced to exchange sex for food.
Gretchen Domek is a medical student at Harvard University, who used to be a medical anthropologist. She studied orphans at a childrens' home in Johannesburg, South Africa, and found that the anti-retroviral drugs have given these children a new lease on life, but created other problems for those who were not expected to live.
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