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The buzz in pop Soda manufacturers claim that they add caffeine to certain soft drinks to enhance flavor. But Hopkins psychopharmacologists now find that few cola drinkers can tell the difference between a cola containing caffeine and one that does not. In taste tests involving 25 volunteers who said they preferred either caffeinated or caffeine-free cola, the researchers found that only two (8 percent) could detect caffeine in a cola containing a concentration equivalent to that found in most brands of cola (0.1 milligrams per milliliter). The researchers reported their findings in the August Archives of Family Medicine. As drugs go, caffeine has relatively few health risks, says Roland Griffiths, who led the study. But it is mildly addictive. "A person who consumes the caffeine equivalent to that found in two to three 12-ounce cans of caffeinated soda per day and then stops will experience withdrawal symptoms-- headache, lethargy, fatigue-- which can be fairly debilitating in some people," he notes. By its addictive nature, caffeine thus may be contributing to soda consumption, says Griffiths, who has studied the chemical's mood-altering effects for the past 15 years. Approximately 70 percent of the soda sold in the United States--including cola, birch beer, and root beer--contains caffeine. Americans consume 15 billion gallons of soda per year, a total that has increased ninefold since 1942, when the American Medical Association noted that soda is of low nutritional value. Studies suggest that drinking soda rather than other more nutritional beverages increases the risk of tooth decay, obesity, and bone fractures, especially in children and teenagers. --Melissa Hendricks
Change needed in PSA screening?
Physicians might best be advised to begin screening men earlier
for prostate cancer and at less frequent intervals, according to
results of a new study done by
researchers at Johns
Hopkins, Merck Research Labs, and the University of North
Carolina.
Standard practice until now has been to start annual PSA
(prostate specific antigen) blood tests at age 50. But by using a
computer model to simulate prostate cancer outcomes under varied
conditions, the researchers came up with a scenario they believe
could save both money and lives: Test men once at 40, again at
45, and then follow up at age 50 with tests every other year.
This approach "would substantially reduce the cost we spend on
prostate screening," and "also prevent more deaths from prostate
cancer, compared with existing screening practices," says Hopkins
urologist H. Ballentine Carter, a member of the research team,
which reported its findings in the September 19 Journal of the
American Medical Association.
Compared to the standard method for screening, Carter says, the
model "showed you would do 3,000 fewer PSA tests and 200 fewer
biopsies for every 1,000 men screened over a lifetime." Prostate
cancer's slow growth and progression means annual screening is
"probably not necessary," he says.
The scientists embarked on this study because of earlier work
Carter did showing that cure rates for prostate cancer tend to be
higher for younger men--probably because their tumors are smaller
and more confined.
While Carter contends that earlier screening could save lives, he
concedes that the new study is based on a computer model, and
thus may not be persuasive enough to "change screening practices
tomorrow." He adds, however, "because this simulation is
trustworthy, it's very strong evidence indeed that what we're
doing now is probably not the best way."
Improving the "Pill's" protection
If all women who took oral contraceptives strictly followed the
directions, only one out of 1,000 would become pregnant in a
year. But in reality, the error rate is much higher: in the
U.S., 69 out of 1,000 women become pregnant during their first
year of using the pill. Worldwide, the figures range from 17
women per 1,000 in Bangladesh, to 105 per 1,000 in Bolivia.
Improved education could significantly reduce the unintended
pregnancy rate among pill users, according to a report in the
Summer 2000 Population Reports.
Each year, 6.8 million unintended pregnancies occur in women who
stop taking the pill--even briefly--and fail to replace it with
another contraceptive.
Another 2 million pregnancies occur due to improper use, such as
accidentally skipping a pill or taking them out of sequence.
"Many women don't know that starting a new pill pack late poses
the greatest risk of pregnancy," says Vera Zlidar, report author
and research analyst at Hopkins's
Center for Communication
Programs. Better counseling, integrating messages about the
pill into television and radio programs, and improved access
could significantly reduce the unintended pregnancy rate, says
Zlidar. --MH
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Q&A with John D. Gearhart Two years ago, Medicine's professor of physiology John D. Gearhart reported that he had isolated embryonic stem cells and developed a method for growing them in culture. The discovery suggested a vast array of therapeutic uses but also prompted ethical objections, which led to a ban on the use of federal funds for stem cell studies, forcing Gearhart to use private funds. In August, the ban was lifted, and the NIH issued guidelines for scientists receiving federal funding, including: Stem cells may only be obtained from extra embryos created for in vitro fertilization that would otherwise be discarded; they must be donated through informed consent; and donors may not be paid.
How will the new NIH guidelines affect your work?
What injuries or illnesses will be the first candidates for
clinical trials? And how soon?
Do you have any qualms about the clinical use of stem
cells?
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