Biomedicine
Council Biologist Discovers Stem Leydig Cells
Population Council
reproductive biologist Matthew P. Hardy and his colleagues have discovered
the precursors of Leydig cells, the primary source of testosterone in males.
These precursor cells, known as stem Leydig cells, were isolated from rats.
Unlike embryonic stem cells, which are derived from embryos, these stem
cells were found in fully developed animals. Stem Leydig cells could
potentially be used to treat hypogonadal boys and men who suffer from
male-hormone deficiency.
Biomedicine
Council Researchers Wrestle with SUMO
Little is understood about the molecular
mechanisms that regulate sperm production—knowledge that would be key to
the development of male contraceptives. Recent research conducted in the
laboratory of Patricia L. Morris, a cell biologist and pharmacologist at the
Population Council’s Center for Biomedical Research, suggests that a protein
known as SUMO-1 is involved in numerous aspects of this process. Gaining a
greater understanding of SUMO’s role in producing sperm, or spermatogenesis,
may lead to insights about male infertility and reveal potential targets for
male contraception.
Biomedicine
Low Chemical Exposure May Speed Male Puberty
A recent, much-publicized study highlighted the adverse
effects that prenatal exposure to chemicals known as phthalates has on
the genital development of male infants. Population Council biomedical
researchers are now studying the effect of prepubertal exposure to these
chemicals on the onset of male puberty. They have found that
exposure to low levels of phthalates can
alter the levels of testosterone (the male sex hormone), increase the
proliferation of cells in the testes, and significantly accelerate the
onset of male puberty. Phthalates are chemicals
used to make plastics—such as those used in food packaging and infant
toys—more flexible. They are also used as stabilizers in many common
cosmetic products, such as nail polish, shampoo, and lotion.
Biomedicine
Emergency Contraception's Mode of Action Clarified
Emergency contraceptive pills, a hormonal treatment that can prevent
pregnancy if taken within 72 hours of unprotected intercourse, have been
the subject of heated debate. At issue is the method’s mechanism of
action: does it prevent the meeting of egg and sperm, or does it prevent
a fertilized egg from implanting in the uterus? Recent research by
members of the Population Council’s International Committee for
Contraception Research (ICCR) and other scientists shows that the most
popular method of emergency contraception appears to work by interfering
with ovulation, thus preventing fertilization, and not by disrupting
events that occur after fertilization.
En
español:
"Se esclarece mecanismo de
acción de la anticoncepción de emergencia" (PDF)
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Biomedicine
Sperm with Bent Tails Point to Possible Male
Contraceptive
New research on mice by scientists at the Population Council and
Rockefeller University sheds light on male infertility. The findings,
reported in the March issue of Developmental Cell, may also lay
the groundwork for a reversible male contraceptive.
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Biomedical Research
Unlocking the Mechanism of Androgen Action
Conducting basic
biomedical research, such as illuminating the events in cells at a molecular
level, is a painstaking endeavor that can take decades to produce major
results. But knowledge garnered from this type of study is crucial to the
formulation of new drugs and the development of successful strategies for
tackling health problems. For more than 15 years, Population Council
biomedical researcher, James F. Catterall and his colleagues have been
studying the genetic mechanisms of action of male sex hormones. His lab has
devised ingenious ways of gleaning information about how androgens regulate
the activity of genes and why they affect certain tissues and not others.
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Reproductive Health
Hormone Choice May Reduce Risks of Menopause Therapy
The type of progestin hormone used in menopausal hormone therapy may have a
large influence on the safety and potential side effects of that therapy,
says Régine Sitruk-Ware, Population Council Executive Director for Product
Research and Development. “The results of a recent study have made many
women and doctors skeptical of hormone therapy in general,” says Sitruk-Ware.
“But this study was based on a single hormone therapy. Other therapies,
particularly ones using different progestin hormones, may have fewer side
effects than the one studied.” Sitruk-Ware recently outlined the properties
of various progestins and progesterone, paying particular attention to
potential risks and benefits.
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Basic Research
Illuminating the Role of Inhibins and Activins in Fertility
All currently available hormonal contraceptives for
women reduce fertility by influencing levels of the steroid hormones
estrogen and progesterone. Altering the level of these hormones, however,
can cause unpleasant side effects in some cases. Population Council
molecular endocrinologist Daniel Bernard is conducting basic research that
may one day lead to a contraceptive for women that leaves estrogen and
progesterone levels largely unaffected, theoretically resulting in fewer
side effects. His research concerns two types of protein hormones that
play a role in women’s fertility: inhibins and activins.
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