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DURHAM, N.C. – Researchers at Duke University are addressing
important unanswered questions about the effectiveness of
proposed "topical microbicides" that when applied
intravaginally would prevent sexually transmitted HIV viral
infections.

The Duke biomedical engineers will explore whether the
virus-killing chemicals would reach the right tissues, adhere
to them, and remain in place over time.

Investigations into the biophysics of candidate topical
microbicides are being led by David Katz in Duke's Pratt School
of Engineering. His laboratory's work is being supported by a
new $2.3 million grant from the National Institutes of Health, as well
as another $90,000 award from the American Foundation for AIDS
Research.

Katz's microbicide research also is supported by grants from
the Food and Drug Administration's Office of Women's Health and
the Contraceptive Research and Development Program – the latter
being a non-profit organization supported by U.S. Agency for
International Development, the Gates Foundation and other
sources. As part of the FDA grant, researchers from the FDA's
Center for Drug Evaluation and Research are collaborating in
the Duke studies.

There is need for such female-controlled prevention methods,
said Katz, who is the Nello L. Teer Jr. Professor of Biomedical
Engineering. The Centers for Disease Control estimates that
between 120,000 and 160,000 adult and adolescent females in the
United States now have AIDS-causing HIV infections, rates that
have increased over the last decade. Most were infected by
heterosexual exposure to HIV.

While researchers hope that women could someday shield
themselves by applying such topical microbicides
intravaginally, "objective, effective standards for evaluation
of such proposed formulations do not yet exist," Katz said.

His laboratory aims to address that deficit by developing a
base of practical knowledge about candidate topical
microbicides. For example, his laboratory is measuring
candidate chemicals' viscosity and surface tension, and
experimentally testing how they flow and adhere to surfaces
similar to those in the vagina.

"Our methods also include theoretical applications of the
laws of physics," said Katz, who is also a professor of
obstetrics and gynecology at the Duke Medical Center. "These
mathematical exercises reveal particular relationships between
properties of formulations and their deployment
characteristics."

Human studies of microbicide formulations in the vagina are
being conducted through a Duke Medical Center clinic, using an
endoscope-like instrument built in Katz's lab. This instrument
measures coating of the tissue surfaces, and detects bare spots
of uncoated tissue that might be particularly vulnerable to
infection, he said.

"We plan to compare the results of our studies in the
laboratory with the measurements of formulation deployment in
women in the clinic," Katz added. "Our goal here is to develop
understanding and confidence in the accuracy of our laboratory
methods to predict features of microbicide deployment that
occur in women in the body."