Thursday, April 17th, 2014
The protein mechanism that allows a sperm and egg to connect to each other and fertilize to become an embryo has been identified by British scientists. More from Reuters:
Fertilization takes place when an egg cell and a sperm cell recognize one another and fuse to form an embryo. But how they recognize each other in order to hook up had remained a mystery.
Researchers said on Wednesday they have identified a protein on the egg cell’s surface that interacts with another protein on the surface of a sperm cell, allowing the two cells to join.
This protein, dubbed Juno in honor of the ancient Roman goddess of fertility and marriage, and its counterpart in sperm, named Izumo after a Japanese marriage shrine, are essential for reproduction in mammals including people, they said.
This new understanding of the role of these two proteins could help improve the treatment of infertility and guide the development of new contraceptives, the researchers said.
“By identifying this interaction between Juno and Izumo, we now know the identity of the receptor proteins found on the surface of our father’s sperm and our mother’s egg that must interact at the moment at which we were conceived,” said Gavin Wright of the Welcome Trust Sanger Institute in Britain, one of the researchers in the study published in the journal Nature.
The researchers are now screening infertile women to try to determine whether problems with the Juno receptor are to blame.
“It is remarkable that about 20 percent of infertility cases have an unexplained cause,” said Enrica Bianchi of the Sanger Institute, another of the researchers.
“We are now asking whether Juno is involved in these cases of unexplained infertility,” Bianchi added.
Wright said that if defects in the Juno receptor are in fact implicated in human infertility, a simple, non-invasive genetic screening test could be developed to identify affected women.
“This then would allow us to guide the fertility treatment,” Wright said, letting affected women proceed directly to a procedure called intracytoplasmic sperm injection involving direct injection of sperm into an egg obtained from in vitro fertilization.
Image: Sperm and egg, via Shutterstock
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Wednesday, April 16th, 2014
New research has linked a mother’s weight with the risk that her baby could either be stillborn or die shortly after birth. Reuters has more:
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The risk was greatest among the most obese women, the authors write in The Journal of the American Medical Association.
“The main message of the study is that maternal overweight and obesity increases the risk of fetal death, stillbirth and infant death,” said Dagfinn Aune, the study’s lead author, from Imperial College London.
“Since excess weight is a potentially modifiable risk factor, further studies should assess whether lifestyle and weight changes modifies the risk of fetal and infant death,” he told Reuters Health in an email.
Stillbirths, when a child dies in the womb toward the end of pregnancy, account for a large part of the estimated 3.6 million neonatal deaths that occur each year, the researchers point out.
Previous studies have linked women’s weight during pregnancy to the risk of their children dying in the womb or shortly after delivery due to complications. Some could not show their findings were not due to chance, however.
For the new study, the researchers pulled together data from 38 studies. Together, these included over 45,000 accounts of child deaths that occurred shortly before or after delivery, although a few studies counted deaths up to one year after birth.
According to the U.S. National Institutes of Health, a person of normal weight would have a body mass index (BMI) – which is a measure of weight in relation to height – between 18.5 and 24.9.
An adult who is 120 pounds and five feet, five inches tall, for example, would have a BMI of 20.
A BMI between 25 and 29.9 is considered overweight, and a score of 30 or above is considered obese.
Friday, April 11th, 2014
Pregnant women who take antidepressant medications during pregnancy may face a higher risk of delivering their babies prematurely, according to a new study that stopped short of declaring a direct link between the two. More from The New York Times:
Researchers reviewed data from 41 studies, some of which controlled for factors like smoking, alcohol or coffee drinking, weight gain during pregnancy, and other behavioral and health issues. They found no increase in the risk of early birth with the use of antidepressants during the first trimester, a 53 percent higher risk over all and a 96 percent higher risk with antidepressant use late in pregnancy.
Depression itself is a risk factor for premature births, and a few studies tried to account for this by using, as a control, a group of women with a diagnosis of depression who did not take antidepressants during their pregnancy. Generally, researchers still found a higher, though diminished, risk from taking antidepressants. The review was published in March in PLOS One.
Does this mean that all pregnant women should avoid these drugs? No, said the senior author, Dr. Adam C. Urato, an assistant professor of maternal-fetal medicine at Tufts University. Risks and benefits have to be balanced, he said.
“It’s very complex, and depends on the severity of the disease,” Dr. Urato added. “The point is that we have to get the right information out so that we can let pregnant women make an informed decision.”
Image: Pregnant woman, via Shutterstock
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Wednesday, April 9th, 2014
For women who are at high risk of developing pre-eclampsia, a potentially dangerous condition in which pregnant women’s blood pressure spikes and their babies need to be delivered immediately, a low dose of aspirin during pregnancy might be a wise preventative measure, according to a new recommendation by a federal government task force. More from The New York Times:
The United States Preventive Services Task Force’s draft recommendation follows a growing scientific consensus that low doses may be beneficial to some high-risk women and their offspring. Low-dose aspirin reduced the risk of pre-eclampsia by 24 percent in clinical trials, according to a systematic review underpinning the new recommendation, which was published in Annals of Internal Medicine.
Low-dose aspirin also reduced the risk of premature birth by 14 percent and of intrauterine growth restriction — a condition in which the fetus doesn’t grow as fast as expected — by 20 percent.
“For every four women who would have gotten pre-eclampsia, one case is prevented,” said Dr. Ira M. Bernstein, the chair of department of obstetrics, gynecology and reproductive sciences at the University of Vermont. “The ability to prevent a quarter of disease is substantial.”
Pre-eclampsia is a condition usually occurring in the second half of pregnancy and characterized by high blood pressure, protein in the urine, liver disease and blood-clotting abnormalities.
It is a leading complication for expectant mothers and their infants, affecting roughly 4 percent of pregnancies nationwide. The only “cure” is delivery. When a pregnant women develops pre-eclampsia in the second trimester, her infant often must be delivered prematurely to avoid severe maternal complications, like stroke.
The task force recommended that women at high risk for pre-eclampsia take 81 milligrams of low-dose aspirin daily after 12 weeks of gestation. High-risk women include those who have had pre-eclampsia in a prior pregnancy, especially those who have had to deliver preterm; women carrying multiple fetuses; and women who had diabetes or high blood pressure at conception.
But the task force also advised that expectant women with multiple moderate-risk factors “may also benefit from low-dose aspirin.” These risks include obesity, a family history of pre-eclampsia, women older than 35, and African-American women.
Image: Pregnant woman taking pill, via Shutterstock
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Thursday, March 27th, 2014
In a new report published by the New England Journal of Medicine, researchers found that some of the influences that cause autism may start during pregnancy. In the study, the brains of autistic children showed differences in certain regions that normally develop in the second trimester of pregnancy. Additional reporting from TIME.com:
Working with autopsy brains of 11 children with autism and 11 children without the disorder who were between the ages of two and 15 years, the scientists focused on 25 genes responsible for specific nerve cell types in the outer layer for the brain, what’s known as the cortex.
“The outcome was fascinating,” says Ed Lein, one of the co-authors of the paper and an investigator at the Allen Institute for Brain Science. “The regions seemed to correspond to the functional symptoms of autism.”
They found that genes that coded for certain excitatory neurons, for example, were not expressed as robustly as they should have been. And these cell disruptions were often in exactly the areas that correlate with autism symptoms – parts of the brain responsible for functions such as communication and interpreting social cues.
In 10 of the 11 autism brains, the researchers found patches of abnormal gene expression, which they discovered in only one of the 11 control samples. And Lein says the disruption may actually be more widespread than he and his colleagues could document, since they only analyzed tiny pieces of the cortex.
The changes very likely occur prenatally, said Lein, a developmental neurobiologist, since these parts of the cortex are generally laid down in the second trimester. That suggests that at least some of autism’s origins may emerge in the womb. But how these factors interact with other, environmental contributors isn’t known yet.
It’s also unclear whether the autistic brains were deficient in the cells that expressed the genes in question, or whether the cells were there but not functioning properly. Figuring that out could lead to new potential treatments or even reversing the changes. “In principle, this could lead to earlier diagnosis and allow us to take advantage of normal parts of the cortex to rewire the brain with appropriate early behavioral interventions,” says Lein.
Some studies already suggest that such behavior therapies, if begun early enough, can change the brains of autistic children to become more similar to those of normal children. What the current study confirms is that it’s never too early to start.
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