News (Updated
March 8, 2009)
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06 Mar 2009 18:19:00 GMT
Sharon Davis
Laboratory
studies, published in Science last week (27 February), showed that a combination
of the drugs meropenem and clavulanate inhibited the growth of 13 separate
strains of XDR-TB.
They
also inhibited the growth of drug-susceptible laboratory strains and those that
mimic the 'latent' state of TB an
inactive phase of TB which is difficult to treat.
The
researchers, from the US National Institute of Allergy and Infectious Diseases
and the US-based Albert Einstein College of Medicine, are optimistic that if the
results are reproduced in humans, an effective XDR-TB treatment could be
produced in a relatively short time.
Meropenem
belongs to a class of antibiotics called b-lactams. These widely-used drugs have
never proved useful in TB treatment as Mycobacterium tuberculosis possesses an
enzyme that breaks them down. But clavulanate inhibits the enzyme, allowing
meropenem to kill M. tuberculosis when the two are used in combination.
Phase
II clinical trials of the drug combination will commence on about 100 patients
in
A
smaller trial on 15-20 TB patients in
Currie
says
He
told SciDev.Net that clavulanate was not yet approved in
This
combination was also tested in the current research, and while not as effective
as meropenem and clavulanate, it is still superior to other drugs, says Currie,
and its use will bypass an estimated 12-month delay before preparations of
clavulanate are approved.
By Maggie Fox, Health and
Science Editor Maggie Fox, Health And Science Editor Wed Mar 4, 5:30 pm ET
WASHINGTON (Reuters) – A
cheap ingredient used in ice cream, cosmetics and found in breast milk helps
protect monkeys against infection with a virus similar to AIDS and might work to
protect women against the virus, researchers reported on Wednesday.
The compound, called
glycerol monolaurate, or GML, appears to stop inflammation and helps keep away
the cells the AIDS virus usually infects, the researchers said.
While it does not provide
100 percent protection, it might greatly reduce a woman's risk of being
infected, and she could use it privately and without hurting her chances of
pregnancy, the researchers reported in the journal Nature.
And it costs pennies a
dose, Ashley Haase and Pat Schlievert of the
"For years, people
have used the compound as an emulsifying agent in a variety of foods ... it is
in breast milk," Schlievert told reporters in a telephone briefing.
GML is being considered as
an additive to tampons because it interferes with bacteria, particularly those
that can cause a potentially fatal infection called toxic shock syndrome.
If it can be shown to work
safely in women, GML might provide the first easy route to a microbicide -- a
gel or a cream that women could use vaginally to protect themselves from
infection with the human immunodeficiency virus, or HIV, which causes AIDS.
HIV infects 33 million
people globally and has killed 25 million. It is transmitted sexually, in blood
and breast milk. In
PROTECTING WOMEN
AIDS experts say many
victims are married women whose husbands will not use condoms and who are often
trying to have children. They need a safe and private way to protect themselves.
A microbicide (pronounced
my-CROW-buh-side) might also protect men who have sex with men.
Haase and Schlievert's
team tested GML, carried in KY jelly, in macaque monkeys. They put the gel into
the vaginas of the monkeys and then applied SIV, a monkey version of HIV.
Four out of five monkeys
never became infected and tests showed GML affected the immune response.
HIV is particularly hard
to fight because it infects the very immune cells the body uses to attack a
virus. When HIV infects an area such as the vagina, the CD4 T-cells rush to
defend against it. The body sends out signaling chemicals called cytokines to
call in more T-cells.
HIV can then infect them
all and spread through the body.
GML appears to stop the
cytokine call for help and stops so many T-cells from rushing to the area, Haase
and Schlievert said. This in turn reduces the opportunity for HIV to take hold.
"This result
represents a highly encouraging new lead in the search for an effective
microbicide to prevent HIV transmission that meets the criteria of safety,
affordability and efficacy," they wrote.
Even if it was only 60
percent effective, such a gel could prevent 2.5 million HIV cases over three
years, they said.
They said they plan to
study their gel in more monkeys for longer periods of time to ensure the gel is
not simply delaying infection rather than preventing it.
(Editing by Will Dunham)
Tue Mar 3, 2009 2:11am EST
By Will Dunham
WASHINGTON
(Reuters) - Scientists have created a strain of the human AIDS virus able to
infect and multiply in monkeys in a step toward testing future vaccines in
monkeys before trying them in people, according to a new study.
This strain of HIV, the
human immunodeficiency virus, was developed by altering a single gene in the
human version to allow it to infect a type of monkey called a pig-tailed
macaque, the researchers said on Monday.
The genetically engineered
virus, once injected into this monkey, proliferates almost as much as it does in
people, but the animal ultimately suppresses it and the virus does not make it
sick, they said.
The strain is called
simian-tropic HIV-1, or stHIV-1.
Researchers hope to be
able to test possible new AIDS drugs and vaccines in monkeys before trying them
in people.
There is a
"cousin" virus to HIV called SIV, or simian immunodeficiency virus,
that causes a disease similar to AIDS in certain types of monkeys.
But this monkey AIDS virus
is not identical to the one that infects people and is not a perfect substitute
for testing drugs and vaccines against HIV.
"If our research is
taken further, we hope that one day perhaps in the not-too-distant future, we'll
be able to make vaccines that are intended for use in humans and the very same
product will be able to be tested in animals before human trials," Paul
Bieniasz of the Rockefeller University in New York, one of the researchers, said
in a telephone interview.
Scientists have struggled
to create an AIDS vaccine.
"If you make a drug
that's effective against HIV, sometimes it works against SIV and sometimes it
doesn't. So that basically devalues SIV as an animal model for doing experiments
involved with developing drugs," Bieniasz said.
"Now if you want to
develop a vaccine, essentially what you have to do is to make a parallel vaccine
for HIV and for SIV. You can test the SIV vaccine in animals and then have to
make the leap of faith that the same approach would work equivalently in
humans."
Writing in the journal
Proceedings of the National Academy of Sciences, the scientists said in making
the genetically engineered virus they removed the HIV version of a gene, known
as vif, and inserted the SIV version. This gene acts to thwart proteins made by
the monkey that that kill viruses.
Bieniasz said the
scientists may need to make additional changes in the stHIV-1 to make it better
for testing vaccines.
The genetically engineered
virus infects the monkeys and during the early course of infection is a
reasonably good mimic of what happens in HIV-infected people, Bieniasz said.
But after initially
spreading in the monkey's body, the animal succeeds in suppressing the virus --
not completely clearing the virus but driving it to very low levels.
"The slight problem
is the monkeys don't go on to develop AIDS, they don't get sick," Bieniasz
said.