The team, led by Patrick Kochanek of the University of Pittsburgh School of
Medicine, is analysing cerebrospinal fluid from children and adults. The
researchers are comparing fluid drained from patients with severe head trauma to
relieve a build-up of pressure with fluid from patients given spinal taps for
other reasons.

Some of the children studied had been injured by adults who admitted abusing
them. Preliminary evidence suggests that victims of abuse usually have a “whole
host of biochemical derangements in the brain”, says Kochanek. His team has
studied a range of biochemicals, including amino acids, immune system signalling
molecules called cytokines, and quinolinic acid, produced by immune cells that
slowly infiltrate the brain after an injury.

“With any metabolite that we look at, seven times out of 10 we see really
high levels in victims of child abuse,” says Kochanek. “I think it really is a
reflection of how severely these infants are injured.”

High levels of quinolinic acid may be the closest thing so far to a “marker”
of child abuse, says Kochanek. Adults who assault children usually don’t take
them straight to hospital—instead, they show up later with a story about
how the child was injured in a fall, or some other “accident”. Because
quinolinic acid accumulates slowly in the brain, its presence may reveal whether
a parent is lying about the timing of the injury. High levels might also
indicate prior injuries, signalling a history of abuse.

Kochanek and his colleagues could find no trace of quinolinic acid in
cerebrospinal fluid taken from 39 adults with head injuries who went to hospital
within 24 hours of being injured. But in a study to be published early next year
in the Journal of Critical Care Medicine, conducted with Melvyn Heyes
of the National Institute of Mental Health near Washington DC, they say that two
out of 17 children with head injuries had high levels of quinolinic acid. Both
children had been abused. A third abused child in the sample did not have
elevated levels of quinolinic acid. Kochanek is now expanding the study. “We
need to study more patients to determine if this preliminary finding holds up or
not,” he says.

The team has also found that the cerebrospinal fluid of babies who have been
shaken violently contains particularly high levels of the amino acid
glutamate—which causes further damage to neurons in injured brains.
Randall Alexander, former vice-chair of the US Advisory Board on Child Abuse and
Neglect and a paediatrician at the Morehouse School of Medicine in Atlanta, says
that this is further evidence that victims of shaken baby syndrome can suffer
more widespread damage than those who receive blows to the head.

Kochanek warns that levels of a single biochemical are unlikely ever to give
a definitive diagnosis of whether or not a child has been abused. But analysed
together with other evidence, such as X-rays, he believes biochemistry could
become an important tool for doctors investigating suspicions of abuse.

The reproductive systems of up to two-thirds of men are infected with
anaerobic bacteria such as Fusobacterium nucleatum and Bacteroides
fragilis. These infections usually go unnoticed unless extremely large
numbers of the bacteria are present, when they can cause pain and discharge.

Bela Molnar of Albert Szent-Györgyi Medical University in Szeged
wondered if these bacteria could be one factor in some men’s fertility problems.
So his team isolated F. nucleatum and B. fragilis from 43
infected men and incubated sperm of normal motility with various concentrations
of the bacteria. These ranged from concentrations comparable to a mild case
without symptoms to a dose equivalent to a raging infection.

Sperm will swim in a culture medium for a day or more. But even in the
samples with low concentrations of bacteria, only 1 per cent of the sperm were
still moving after 18 hours. At the highest dose, they all stopped moving after
3 hours.

Molnar says that the bacteria may inhibit sperm motility in several ways: by
competing for fructose, a sugar that sperm need for energy; by producing
products that are toxic to sperm; or by physically interfering with the lashing
of sperm tails.

If infertile men have asymptomatic infections, Molnar thinks they should be
given broad-spectrum antibiotics for three months to eliminate the bacteria,
before beginning IVF. “We should first treat them and let them try to conceive
the normal way,” he says.

In the autumn of 1996, David Spiller of the University of California at Davis
and Jonathan Losos of Washington University in St Louis counted spiders and
lizards on 19 small islands in the Bahamas as part of a study of food chains.
Just hours after they completed their census, the ferocious hurricane Lili
struck.

The next day, the researchers salvaged their boat from a tree and went back
to count the spiders and lizards that remained. A year later, they surveyed the
islands again to assess how the animals had recovered.

The researchers found that on islands that were sheltered from the storm by
other nearby islands, lizards survived better than spiders. But the spiders
bounced back within a year, while the lizards remained at immediate post-storm
levels. This fits with the theory that small animals that breed fast can recover
their populations faster than larger animals.

On unprotected islands, all spiders and lizards were initially wiped out.
After one year, spiders had returned to the islands, but only one of the exposed
islands had any lizards. Spiller says that while lizards rarely cross water,
spiders can ride on the wind and repopulate islands quickly (Science,
vol 281, p 695).

Spiller says the work has been a rare chance to see how natural catastrophes
alter species distributions. “Many ecological propositions are sort of
common-sense theories, and until hard data come along, they cannot be taken as
facts,” he says. “The hurricane caused a lot of grief for many people, but from
a scientific view, it was a once-in-a-lifetime opportunity.”

Sexually transmitted diseases (STDs), which cause genital ulceration or
discharge, can increase the risk of transmitting or acquiring HIV. So in theory,
treating STDs should slow the spread of AIDS. And in 1995, a study in Tanzania
showed that aggressive antibiotic treatment cut HIV transmission rates by more
than 40 per cent (This Week, 2 September 1995, p 4). At the time, experts argued
that treating STDs might be the best way of controlling Africa’s AIDS
epidemic.

The disappointing results from the new study, reported last week at the 12th
World AIDS Conference in Geneva, may force a rethink. “The interaction between
STDs and HIV is more complex than previously thought,” says Maria Wawer of
Columbia University School of Public Health in New York, who presented the
findings.

Wawer and her colleagues at Johns Hopkins University in Baltimore, Makerere
University in Kampala and the Ugandan Ministry of Health worked in 56 villages
in the Rakai region. About 16 per cent of the villagers—whose ages ranged
from 15 to 59 years—were infected with HIV at the start of the study. Ten
per cent had syphilis, 4 per cent chlamydia and 2 per cent gonorrhoea. Half of
the women in the study had bacterial vaginosis.

In 1994, some 6000 villagers were treated with broad-spectrum antibiotics
effective against common STDs. A control group was given a drug that combats
parasitic worms. These treatments were repeated twice, at 10-month
intervals.

After the second 10-month follow-up, the rate of STDs in the group given
antibiotics had been cut by half for each infection apart from bacterial
vaginosis, which does not respond well to treatment. But there was no difference
in the number of people becoming HIV-positive. In both groups the rate of new
HIV infections remained at around 1.5 per cent per year.

“What we found was that STDs overall contributed relatively little to HIV
infection in this group,” says Wawer. “One reasonable theory we are now
examining is that the rate of infection with HIV was so high that it overwhelmed
the STD effect.” Among the rural Tanzanians in the successful 1995 study, 4 per
cent were HIV-positive—one-quarter of the proportion in the Ugandan study
population.

“The results of this study make us think more carefully about the variations
in the epidemics of different areas,” says Nelson Sewankambo, the Ugandan
principal investigator at Makerere. Helene Gayle of the US Centers for Disease
Control and Prevention in Atlanta agrees: “The studies show that interventions
will need to depend on the circumstances of the local HIV epidemic.”

BY WORKING out how to extract aromas from foods, two scientists in California
may have solved one of America’s most vexing environmental problems: cleaning up
groundwater contaminated with a potentially carcinogenic fuel additive.

To improve the efficiency of combustion and to minimise air pollution, many
US states have added methyl tertiary-butyl ether (MTBE) to vehicle
fuel. But MTBE dissolves readily in water and is building up in reservoirs of
groundwater used for drinking, especially in California.

Chemical engineer Marc Sims, who runs a company in Berkeley called Marc Sims
Supercritical Fluid Extraction, and molecular biologist Jim Robinson, who has a
company in Livermore called Setec, have developed a powerful yet simple device
for separating molecules using liquid carbon dioxide. Their contraption sends
fluid through a tube made of polypropylene membranes suspended in a chamber of
liquid CO₂. The CO₂, but not the fluid, can flow back and
forth across the membranes. It collects molecules that prefer to dissolve in
liquid CO₂. These molecules gradually disappear from the fluid, which
is left slightly carbonated.

The researchers originally used their device, called PoroCrit, to extract the
chemicals responsible for the aromas in foods such as orange, lemon, apple,
garlic, onion and butter. But while they were busy purifying these essences,
problems with MTBE in groundwater hit the news in California. “It took a little
while to sink in,” says Sims. “It’s an ether; exactly the sort of compound that
we’ve been extracting all along.”

Sims and Robinson began to experiment with MTBE-contaminated water about
three months ago. They found that just one pass through their device reduced
MTBE levels up to one million-fold. They are now testing a larger model that can
purify water at a rate of 10 litres per minute.

Existing methods of decontamination do not work very well for MTBE. Sims and
Robinson are confident that PoroCrit will be the most effective way to clean up
MTBE-tainted water. The researchers have been contacted by the California state
government, fuel associations and the federal Environmental Protection
Agency.

Although the US government classifies MTBE as a “possible carcinogen” only at
concentrations above 20 parts per billion, water smells of turpentine when the
chemical is present at just 15 ppb. “People can smell it when they’re in the
shower,” says Sims. However, the slightly fizzy liquid produced by the PoroCrit
device has no aroma at all.

Robert Dow of the pharmaceuticals company Pfizer’s laboratories in Groton,
Connecticut, told last week’s meeting of the American Chemical Society in San
Francisco that his team has made a molecule that can boost the metabolism of
rats by almost a third without increasing their appetites.

The molecule, called CP-331679, mimics one effect of adrenaline. This hormone
binds to three types of receptors: one in the heart, which boosts the heart
rate; another in blood vessels, which causes them to dilate; and the third on
the surface of fat storage cells, which causes fats to be broken down for
energy.

Dow’s team targeted the third type, called beta-3 adrenergic receptors,
reasoning that this would help to burn fat without affecting the cardiovascular
system. The researchers tinkered with molecules known to stimulate adrenaline
receptors until they came up with one that affected just the beta-3
receptors.

Dow has not yet tested the molecule in humans, but if its effects on rats
were translated into human terms, people would shed just over a kilogram a week.
However, human fats occur in different proportions to those of rats, which could
limit the molecule’s effect. Dow’s molecule works on the brown fat of rats, of
which adult humans have very little.

David Kreutter, a member of the Pfizer team, stresses that overweight people
will always need to exercise. “No drug should be considered a substitute for
lifestyle changes,” he says.

Other drugs companies are also betting that beta-3 adrenergic stimulators
will improve on today’s diet pills. Merck of Rahway in New Jersey, for instance,
has a beta-3 adrenergic stimulator under development.