eyespy
Eyespy brings you the latest quirky medical stories
from around the world
Against Nature?, an
exhibition at the Natural History Museum in Oslo, does not tell biologists
anything new. Homosexuality has been noted in more than 1500 species so
far, and its prevalence has been known since antiquity, Aristotle being one
observer of the phenomenon. The evolutionary origins of sexual orientation
remain a mystery, particularly for exclusive homosexuality. But
that's not the main reason the museum held this exhibition to wide
acclaim and the disapproval of churches. It's just to let us know
that gay men and women do not "disturb" natural order. In
Norway, where 14 year olds learn about homosexuality as part of their
national curriculum, this exhibition can only serve as positive
reinforcement (Economist 2006 Oct 26).
Photos.com
We're here and queer
First left handedness, then dogs, and now it's
red meat. The list of (arguably dubious) risk factors for breast cancer in
premenopausal women is rising. Researchers in the United States followed up
more than 90 000 women for 12 years (Archives of
Internal Medicine 2006;166:2253-9). Having
one and a half servings of red meat a day almost doubled the risk of
hormone receptor positive breast cancer compared with having three or fewer
servings a week. Two arguments have been advanced. One relates to the
chemicals that are used to process red meat and the second to the use of
growth hormones in animals in the US. The responsible media, of course,
cooked up sensational headlines.
The modish field of stem cell research holds great
promises, and US scientists have moved a step closer to manipulating them
for use in diabetes (Nature Biotechnology2006;24:1392-401, doi: 10.1038/nbt1259). Human embryonic
stem cells have now been coaxed through the stages of normal fetal
pancreatic development in the hope that they might become functional b cells, which produce
insulin. Although the stem cells did produce insulin, and at high
concentrations, this did not happen in response to the body's normal
chemical triggers.
If you thought a Y chromosome entitled you to
masculinity, think again. Even if you have two X chromosomes (the female
complement), you might develop as a male. This conclusion comes from a
study of four brothers, each of whom had two Xs instead of the normal male
complement, XY (Nature Gene 2006;38:1304-9, doi: 10.1038/ng1907). Most female to male
sex reversals occur when the second X chromosome inherited from the father
acquires the sex determining region of the Y chromosome, contained in the
gene SRY. The brothers, however, had no copy of SRY, instead they harboured
a mutation in a gene called RSPO1. Researchers propose that this is
necessary for the formation of ovaries, and, in its absence, the embryo
will develop testes.
The hunt for the next big antibiotic is gathering
momentum. Platensimycin is naturally produced by the bacterium Streptomyces platensis and has
been shown to belong to a new class of antibiotic. It might be effective
against so called superbugs, which are resistant to many established
antibiotics, but only in the form of a pure single optical isomer. A team
from California has completed the first step and synthesised a racemic
mixture from which the right enantiomer must now be extracted (Angewandte Chemie International Edition 2006;45:7086-90, doi: 10.1002/anie.200 892).
Who would you most trust to tell the truth? Nine out
of 10 members (92%) of the British public place most trust in their doctor.
A survey by the Royal College of Physicians found that the next most
trusted people are teachers, professors, and judges. But if medics are at
92% and journalists are at 19% where does that leave Eyespy
(www.guardian.co.uk)?
Any neuroscientist, when asked about the function of
chloride channels in neurones, would usually answer in one
word-housekeeping. By maintaining electric polarity across the
membrane and by preserving cell volume, they are crucial for the normal
firing of neurones in response to stimuli. Another function attributed to
these ion channels during early development of neurones is exactly the
opposite of what it does in adults (Neuron 2006;52:321-33). They amplify cell to cell
communication, thereby propagating, rather than promoting recovery
from, action potentials. The housekeeper has more than one job after all.
It takes a great deal for humans to stay in shape,
particularly in the age of supermodels and metrosexuals. But how do cells
within the body, particularly epithelial cells, maintain their shape? Say
hello to Tuba, a protein that controls the shaping of junctions between
cells by modulating the local activation of an enzyme that is essential for
the proper functioning of the cytoskeleton within. The ever so popular RNA
interference was used to reduce the activity of the gene for Tuba, and
researchers say that the epithelial cells looked "curved and
slack." And that is not good for your skin (Journal of Cell Biology 2006;175:
135-46).
The drug ecstasy is supposed to be bad for the brain,
because, the story went, it damages neurones signalled by serotonin, and
these have a say in memory storage. But when researchers from the United
States gave pregnant rats the drug, they saw no damage in the newborn pups
but a threefold rise in the number of highly functional dopamine producing
cells. The same findings have been replicated in vitro, using cultured
embryonic dopaminergic neurones. Given that the loss of such neurones lies
at the heart of Parkinson's disease, this could be a possible
therapeutic candidate-in rats at least (New
Scientist 2006 Oct 28).
When Barbara McClintock discovered "jumping
genes" or transposons, little did she realise the importance of the
phenomenon to cell biology. As well as playing important roles in processes
such as virus replication inside human cells, they are involved in gene
amplification-that is, increasing the number of copies of a given
gene. Researchers have discovered a new mechanism of potent gene
amplification in yeasts that involves transposons flanking a crucial region
of the organism's genome. The latter includes genes that are
important for DNA replication. Forty five per cent of the human genome
consists of transposons, which means that this mechanism may be more than
relevant to human physiology (Nature 2006;443:1003-7).
Adjudin is a novel drug that once held great promise to
become the first "male pill." But hopes soon faded because oral
intake caused severe hepatitis and muscular deterioration in rats. The
solution, says the same team that initially found the drug, lies in
coupling Adjudin to a mutant form of follicle stimulating hormone, which
targets the testes and triggers sperm development (Nature Medicine 2006;12:1323-8,
doi: 10.1038/nm1420). Injection into the rats rendered them infertile
within four weeks, and they stayed so for another four weeks. Because the
average man is unlikely to want to inject himself every four weeks, the
development of a gel is now underway.
Fountain of youth. Fat, healthy, and tipsy. Grapes
versus gluttony. The media frenzy, as shown by these headlines, is
understandable because researchers have found that resveratrol, a compound
found in red grapes, improves the health and lifespan of mice on a high
calorie diet (Nature 2006;444:
280-1). Mice fed on the same diet without resveratrol had a shorter life.
The compound itself did not prevent obesity, but it seems able to prevent
the start of disease associated with obesity, and it conferred a longer
life. You may think you've found an excuse to relax with a glass of
red wine, but it contains only 0.3% of the resveratrol dose that was given
to the gluttonous mice, and, increasing the dose via the wine is certainly
not a good idea.
studentBMJ 2006;14:441-484 December ISSN 0966-6494
