Researchers report that very minute quantities of the hormone found in the birth control pill alter sperm development in rainbow trout by changing the number of chromosomes, which can lead to lower survival and long-term health problems in the offspring. This error in cell division is called aneuploidy.
ABOUT half of all miscarriages and many common human birth defects occur because embryos receive too many or too few chromosomes from their mother. Now geneticists in the US believe they know why. They have identified a hiccup in the production of human egg cells that triggers a tug of war over a single chromosome.
Human cells normally have 46 chromosomes. But egg and sperm cells have 23. This is because their precursors divide twice to produce four cells, each with half the normal number of chromosomes. This process, known as meiosis, is designed to ensure that each parent donates only one copy of each chromosome to their child.
In practice, however, this equable allocation of chromosomes sometimes breaks down. The best known example is Down's syndrome, caused by an embryo inheriting an extra copy of chromosome 21. "Until now we haven't had a clue what causes these chromosome segregation errors," says Terry Hassold of Case Western Reserve University in Cleveland, Ohio.
Hassold's group joined forces with a team led by Stephanie Sherman of Emory University in Atlanta, Georgia, to study chromosome 16. Although less well-known than Down's syndrome, faulty chromosome 16 segregation is even more common. More than one in 100 embryos have an extra copy of chromosome 16, and this inevitably results in spontaneous abortion.
The researchers examined 62 miscarried embryos for some hint of what went wrong. They knew that in the early part of meiosis, chromosomes line up like pairs of shoes set instep to instep at the centre of the cell. The outer edge of each chromosome then attaches to protein cables that pull it towards one end of the cell, so that each chromosome ends up in the correct daughter cell when cell division is completed.
Hassold, Sherman and their colleagues suspected that the problem might lie in a feature of meiosis called crossing over. In this process, which occurs many times in each chromosome pair, the two chromosomes break and reattach to each other, thus swapping portions of their genetic material. This introduces extra genetic variability and also serves two other functions. First, the crossovers weave the two chromosomes together and prevent them from moving away from one another before the cell is ready to divide. And secondly, by holding the "instep" sides of the paired chromosomes closely together, the crossovers ensure that each chromosome can only attach to a protein cable on one side.
The researchers compared the genetic sequence of parts of chromosome 16 from the miscarried embryos and their mothers. This revealed that the rate of crossing over for the eggs that gave rise to these embryos had been normal near the ends of the chromosomes, but reduced by about one-third near the middle (American Journal of Human Genetics, vol 57, p 867).
This dearth of crossing over could explain the problem, says Hassold, as it would mean that the two copies of chromosome 16 were not properly anchored together at the start of meiosis. The chromosomes would have flopped around, he says, exposing their inner edges. Hassold speculates that the exposed inner edge of one copy of chromosome 16 became attached to a protein cable. Because the same chromosome was also attached on its other side, a tug of war began between the two daughter cells. If the wrong cell won the battle, the loser would be left without chromosome 16 and would soon die. The other would end up with two copies, and after dividing again would give two abnormal eggs.
But what could cause the lack of crossing over? Hassold believes the culprit could lie among the proteins that help bring paired chromosomes together, or which cut and splice DNA to form the crossovers. In simpler organisms such as yeast, similar abnormalities can result if one of these meiosis proteins is missing or mutated.
From issue 2000 of New Scientist magazine, 21 October 1995, page 20
Source: http://www.newscientist.com/article/mg14820002.900-tugofwar-that-can-wreck-a-fetus.html Recent Keyword Searches: can excericise make you miscarriage, secrets that help prevent miscarriage, age related miscarriages keep trying, miscarriage fsh successful pregnancy, odds of miscarrying 40, miscarriage is high at age 42 using own eggs, chances of miscarriage at age 45, miscarriage how long does it take for hormone levels to normalise?, remedies to avoid miscarriage, misdiagnosed miscarriages
Instead of holding a woman responsible for recurrent pregnancy loss, try blaming unhealthy sperms, say Indian scientists who have developed new technology to study the quality of sperms.
When a female faces miscarriage more than twice in a row, it's called recurrent pregnancy loss. In around 80 per cent such cases, imperfect and inefficient sperms lead to a weak embryo formation, finally ending with miscarriage, say scientists at the National Institute of Health and Family Welfare (NIHFW).
"We took the cases of 35 women who were facing recurrent pregnancy loss. As we did not find much problem with them, the samples of their husbands' semen were tested in our laboratory," said MM Misro, a scientist at NIHFW's department of biomedicine.
"Though the sperm count and mobility were almost normal, we found that 80 per cent of the cases were because of defects in sperms," Misro, who carried out the study, told IANS.
"While 20 cases of the 35 showed a defect in the sperm plasma membrane and enzyme in the top of the sperm (Acrosome), 29 cases reported problems in the nuclear chromatin de-condensation."
The new findings on sperm quality are greatly expected to help women who suffer from recurrent pregnancy loss.
"The revelation is startling and will help millions of such women who are socially ridiculed. This study proves that men should not blame women alone for recurrent miscarriage. They are equally responsible," he added.
Elaborating on the inferior quality of sperms, Misro said environmental pollution is one of the factors. "Through polluted air and water, a compound called Xenoestrogen enters our bodies and alternates the reproductive hormone."
Misro said the technology developed by him in the institute not only keeps track of sperm mobility and its count (20 million per millilitre) but is also capable of testing three other aspects.
"Along with mobility and sperm count it allows three tests - hypo osmotic swelling, Acrosome status and nuclear chromatin de-condensation - to stay assured about the competence of sperms leading to a healthy pregnancy."
Misro claimed the new technology was unique and they were trying to patent it.
"It would be of great help for sperm banks and clients going to fetch them. I think a man should test these above factors in his sperm to make sure that his wife does not suffer."
Source: http://www.hindustantimes.com/StoryPage/StoryPage.aspx?id=a24673b1-39fa-4ba1-a5ca-efd0f6319fd4&ParentID=87312da7-0a5f-44b4-8aad-610f696c6561&MatchID1=4501&TeamID1=2&TeamID2=6&MatchType1=1&SeriesID1=1122&PrimaryID=4501&Headline=Don't+blame+women+for+pregnancy+loss
New Delhi, June 24 (IANS) - Instead of holding a woman responsible for recurrent pregnancy loss, try blaming unhealthy sperms, say Indian scientists who have developed new technology to study the quality of sperms.
When a female faces miscarriage more than twice in a row, it's called recurrent pregnancy loss. In around 80 percent such cases, imperfect and inefficient sperms lead to a weak embryo formation, finally ending with miscarriage, say scientists at the National Institute of Health and Family Welfare (NIHFW).
'We took the cases of 35 women who were facing recurrent pregnancy loss. As we did not find much problem with them, the samples of their husbands' semen were tested in our laboratory,' said M.M. Misro, a scientist at NIHFW's department of biomedicine.
'Though the sperm count and mobility were almost normal, we found that 80 percent of the cases were because of defects in sperms,' Misro, who carried out the study, told IANS.
'While 20 cases of the 35 showed a defect in the sperm plasma membrane and enzyme in the top of the sperm (Acrosome), 29 cases reported problems in the nuclear chromatin de-condensation.'
The new findings on sperm quality are greatly expected to help women who suffer from recurrent pregnancy loss.
'The revelation is startling and will help millions of such women who are socially ridiculed. This study proves that men should not blame women alone for recurrent miscarriage. They are equally responsible,' he added.
Elaborating on the inferior quality of sperms, Misro said environmental pollution is one of the factors. 'Through polluted air and water, a compound called Xenoestrogen enters our bodies and alternates the reproductive hormone.'
Misro said the technology developed by him in the institute not only keeps track of sperm mobility and its count (20 million per millilitre) but is also capable of testing three other aspects.
'Along with mobility and sperm count it allows three tests - hypo osmotic swelling, Acrosome status and nuclear chromatin de-condensation - to stay assured about the competence of sperms leading to a healthy pregnancy.'
Misro claimed the new technology was unique and they were trying to patent it.
'It would be of great help for sperm banks and clients going to fetch them. I think a man should test these above factors in his sperm to make sure that his wife does not suffer.'
Source: http://www.andhracafe.com/index.php?m=show&id=24375
In a study conducted at Columbia University's Mailman School of Public Health and the New York Psychiatric Institute researchers found that increasing paternal age is significantly associated with increased rates of spontaneous abortion, a pregnancy loss occurring before twenty weeks of gestation. Results indicate that as the male partner ages there is a steady increase in rate of miscarriage. Women with partners aged 35 or older had nearly three times as many miscarriages as compared with women conceiving with men younger than 25 years of age. This finding is independent of the woman's age and not explained by other factors such as diabetes, smoking, or previous spontaneous abortions, and adds to the growing realization of the importance of paternal characteristics for successful reproductive outcome.
"There has been a tremendous amount of research on women, and how their characteristics affect pregnancy outcomes. Of course, women's importance and centrality to pregnancy cannot be overstated. However, scientists seem to have forgotten that men are equal partners in reproduction, and their influence should be studied to the same degree. Our group has focused on men's influence on the health of their offspring, and we have made some fascinating discoveries," said Karine Kleinhaus, MD, MPH currently in Columbia's Department of Psychiatry and first author of the study. "This study shows how a man's age affects the likelihood of miscarriage."
Earlier research by the Columbia scientists showed that older men's wives suffer from preeclampsia, while the offspring of older men are more likely to get schizophrenia. "This is not as surprising as it may sound at first, as it was already shown by other researchers that older men have more abnormalities in their sperm, and that their children are more susceptible to certain birth defects," observes Dr. Klienhaus. In fact, the American Society for Reproductive Medicine has set an upper age limit of 40 years old for semen donors because of the increased risk of genetic abnormalities in the offspring of older fathers.
The international team of scientists involved in the study used a large historical data set containing information on many characteristics of mothers and fathers that might contribute to spontaneous abortion. The researchers analyzed data from the ante-natal or post-partum interviews of 13,865 women. This data was recorded in the Jerusalem Perinatal Study, a population-based cohort derived from 92,408 births in Jerusalem in 1964-1976.
Accordingly, the study, which focused exclusively on spontaneous abortion as the outcome, has as one of its strengths its large sample size and its extensive data, which permit consideration of important potential confounders not included together in other analyses. These include variables such as maternal diabetes, parity, history of prior spontaneous and induced abortions, and history of maternal smoking, and socioeconomic status.
The cohort used for this study is unique, with immigrants from many origins, including Iran, Iraq, Afghanistan and countries of North Africa, as well as Central and Eastern Europe. "This broad mix of backgrounds makes our study findings more generalizable," observed Susan Harlap, MD, professor of clinical epidemiology in the Mailman School of Public Health's Department of Epidemiology, and the leader of this research team. "While several previous studies suggested that father's age might contribute to miscarriage, they failed to clarify whether there is a cut-off age or a progressive trend over the whole range of ages."
The study findings generate strong support for the association of increasing paternal age with increasing rates of spontaneous abortion, and are corroborated by other published studies. "Advanced paternal age may result in only a slight increase in the chance of spontaneous abortion for a specific couple. Nevertheless, as child bearing is increasingly delayed in Western societies, this study provides important information for people who are planning their families," said Dr. Kleinhaus. "The study also adds to a growing understanding of how men's age, health, and occupations can affect their partner's pregnancies and the offspring's future development."
Full article: http://www.medicalnewstoday.com/medicalnews.php?newsid=48848
[BioNews, London] Air pollution can damage sperm, reducing the chances of conception and raising the risk of miscarriage, say researchers based in the Czech Republic. The study, published in the journal Human Reproduction, also shows that a man's sperm quality will improve again if pollution levels drop. The findings show that the effects of air pollution on sperm are temporary, suggesting that it affects mature sperm late in their development, say the scientists.
The team studied men living in Teplice, a town in the Czech Republic that has high levels of air pollution during the winter months. They monitored 35 men for two years, and found that their sperm quality deteriorated during the winter, and improved significantly during the months when air quality improved.
Full article: http://www.ivf.net/content/index.php?page=out&id=1659
UroToday.com - Dewan and colleagues conducted a study which demonstrated that the prevalence of y-chromosome microdeletions was higher in patients (couples) undergoing evaluation for recurrent pregnancy loss (n=17) compared to 18 fertile couples without pregnancy loss and 10 infertile men.
Eighty-two (82%) percent of the men from the couples with recurrent pregnancy loss as compared to 0% in the normally fertile males and 20% in the infertile males were found to have microdeletions in the AZFc region of the Y chromosome.
These findings do not only provide an explanation for recurrent miscarriage in a select population, but may have implications for couples utilizing testicular sperm acquisition and IVF/ICSI. This finding supports the "complete" genetic evaluation for patients entertaining the utilization of these technologies.
Full article: http://www.medicalnewstoday.com/medicalnews.php?newsid=58697
Researchers report that very minute quantities of the hormone found in the birth control pill alter sperm development in rainbow trout by changing the number of chromosomes, which can lead to lower survival and long-term health problems in the offspring. This error in cell division is called aneuploidy. 
