Study
Shows Cause Of Infertility In Some Women With Endometriosis
Key Molecule Lacking
In Uterine Wall
Some women who have
infertility as a result of endometriosis lack molecules in the
uterus that allow the embryo to attach to the uterine wall,
according to a report in the medical journal Endocrinology.
The researchers suspect
that because the embryo cannot attach to the uterine wall, a
pregnancy cannot become established, and infertility results.
Endometriosis is a
major cause of infertility, occurring in from 35 percent to
50 percent of women who have difficulty becoming pregnant.
The researchers also
reported that a number of genes present in the uteri of women
with endometriosis appear to be functioning inappropriately.
Many of the genes identified in this study had not been shown
previously to contribute to endometriosis and the infertility
that commonly accompanies the disorder.
"The causes of endometriosis
and of the infertility that's associated with it have eluded
scientists for many years," says Dr. Duane Alexander, director
of the National Institute of Child Health and Human
Development (NICHD), at the National Institutes
of Health (NIH).
"This study provides
a better understanding of this disease, and may lead to new
therapies to treat women who have the disorder," Dr. Alexander
says.
The NICHD
and the Office of Research on Women's Health
provided part of the funding for the study.
The research builds
upon an earlier NICHD-funded study, which reported
that the molecule L-selectin needs to be present on the uterine
wall before an embryo can attach itself to the uterus and a
pregnancy can begin.
In the current study,
researchers found that at the time the uterus is most receptive
to the embryo, women with infertility because of endometriosis
have very low levels of an enzyme that is involved in synthesizing
the ligand for L-selectin.
The ligand is a rubber-band
like molecule that tethers L-selectin to the wall of the uterus.
Because the women lack the enzyme that makes the L-selectin
ligand, the embryo may not be able to attach to the uterine
wall, and a pregnancy could not begin.
Endometriosis is a
disorder in which endometrial tissue -tissue that normally lines
the inside of the uterus - begins growing in other areas
within a woman's abdomen, including on the fallopian tubes,
on the outside of the uterus, the ovaries, or intestines.
This disorder affects
10 percent to 15 percent of women of reproductive age and often
causes pelvic pain.
Scientists
Study Genes' Role
In this multicenter
study, researchers collected samples of endometrium from
15 non-pregnant volunteers, eight with endometriosis and seven
without. They did this during the "window of implantation,"
the days of a woman's menstrual cycle (day 20-24 of a 28-day
cycle) when the uterus is receptive to an embryo.
The scientists in
this study used a new technology called microarray analysis,
which makes it possible to screen a large number of genes at
one time. This allows researchers to identify genes much more
quickly than do traditional methods that look for only one gene
at a time.
The researchers measured
gene expression - the turning on or off of a particular
gene.
They analyzed over
12,000 genes. They found 91 genes that had more than a two-fold
increase in gene expression in women with endometriosis, compared
to those without the disease, and 115 genes that had more than
a two-fold decrease in expression in women with endometriosis
compared to those without.
These genes are likely
to play a role in the development of endometriosis in the pelvis
and its associated infertility.
"This study's findings
support the theory that women who have this abnormal tissue
are prone to develop endometriosis and its infertility," says
the study's senior author, Dr. Linda Giudice, director of the
Center for Research on Women's Health and Reproductive Medicine
at Stanford University.
Hope
for New Treatments
Dr. Giudice explains
that the study's findings might lead to a new way to screen
women for the disease. Currently, diagnosis requires a laparoscopy
(a procedure in which a small incision is made in the abdomen)
or laparotomy (a larger incision is made), usually with a general
anesthetic.
This new research
may one day enable scientists to develop a less invasive test,
based on the detection of abnormal gene activity, she says.
Dr. Giudice says
that the study's findings need to be verified in larger studies
of women who have endometriosis.
Nonetheless, she says,
"This now offers an opportunity to create drugs to correct this
error in gene expression, and therefore a treatment for endometriosis-related
infertility."
Always consult your
physician for a diagnosis.
What
Is Endometriosis?
The name comes from
the word "endometrium", which is the tissue that lines the uterus.
During a woman's regular
menstrual cycle, this tissue builds up and is shed if she does
not become pregnant. Women with endometriosis develop tissue
that looks and acts like endometrial tissue outside the uterus,
usually on other reproductive organs inside the pelvis or in
the abdominal cavity.
Each month, this misplaced
tissue responds to the hormonal changes of the menstrual cycle
by building up and breaking down just as the endometrium does,
resulting in internal bleeding.
Unlike menstrual fluid
from the uterus which is shed by the body, blood from the misplaced
tissue has nowhere to go, resulting in the tissues surrounding
the endometriosis becoming inflamed or swollen.
This process can produce
scar tissue around the area which may develop into lesions or
growths. In some cases, particularly when an ovary is involved,
the blood can become embedded in the tissue where it is located,
forming blood blisters that may become surrounded by a fibrous
cyst.
Always consult your
physician for more information.
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August 2003
Study
Shows Cause Of Infertility In Some Women With Endometriosis
Scientists
Study Genes' Role
Hope
for New Treatments
What
Is Endometriosis?
Calcium
Can Be Critical Before Menopause
Nutritional
Needs After Menopause
Online
Resources
Calcium
Can Be Critical Before Menopause
Many women start taking
calcium supplements during menopause, but calcium deficiency
increasingly is being seen in younger women, according to a
report in the Mayo Clinic Women's HealthSource.
Women who are not
getting enough calcium in their diets should take a supplement,
regardless of their age, experts say.
Women should ask their
physician how much calcium is needed because the amount required
changes based on age and health factors.
A physician also can
recommend which kind of calcium supplement should be taken,
when to take it for best absorption, and if it should be combined
with vitamin D or other minerals.
If dietary intake
of calcium is insufficient, calcium supplements can provide
special benefit to the bones at certain times in life, such
as puberty or in early menopause.
But at any age, calcium
benefits a woman's bones as well as muscles and nerves.
A well-balanced diet
can provide all the calcium a woman needs. Good sources
of calcium include: dairy products; vegetables such as broccoli,
spinach, brussels sprouts and kale; tofu; calcium-fortified
juices, cereals and breads; and canned fish, such as salmon.
Always consult your
physician for a diagnosis.
Nutritional
Needs After Menopause
As a person ages,
nutritional requirements change.
A premenopausal woman
should consume about 1,000 mg of calcium daily. Women after
menopause should consume 1,200 mg of calcium per day, according
the American Academy of Orthopaedic Surgeons.
Vitamin D is also
very important for calcium absorption and bone formation.
According to a 1992
study, women with postmenopausal osteoporosis who took vitamin
D for three years, significantly reduced their risk of spinal
fractures.
This issue is controversial,
however, as vitamin D can cause kidney stones, constipation,
or abdominal pain, especially in women with kidney problems.
Other nutritional
guidelines recommended by the National Research Council
of the National Institutes of Health include:
Choose foods low in
fat, saturated fat, and cholesterol. Fat intake should be less
than 30 percent of daily calorie intake.
Eat fruits, vegetables,
and whole grain cereal products, especially those high in vitamin
C and beta carotene. Persons of all ages should consume 20 to
30 grams of fiber daily.
Avoid foods and drinks
with processed sugar, as many of these products contain empty
calories and promote weight gain.
Avoid salt-cured and
smoked foods such as sausages, smoked fish, ham, bacon, bologna,
and hot dogs. These foods are high in sodium, which can lead
to high blood pressure, a serious risk for aging women.
Always consult your physician for more information.
Online Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
College of Sports Medicine
American
Society for Reproductive Medicine (ASRM)
Centers
for Disease Control and Prevention (CDC)
HealthierUS.Gov
National
Institutes of Health (NIH)
National
Women's Health Information Center
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