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Posts Tagged ‘fetus’

Chemical Cocktail Turns Mice Clear

August 31st, 2011 08:32 admin View Comments

Science

sciencehabit writes “Researchers have serendipitously discovered that a mixture of urea, glycerol, and soap makes membranes transparent. When they tried the mixture on a developing mouse fetus, they found that it removed all of the pigment from the cells, rendering the fetus completely transparent. The technique allowed scientists to see fluorescent neurons buried several millimeters in the brain.”

Source: Chemical Cocktail Turns Mice Clear

Could a Fetus’s Genetic Disorder Be Cured by Mom’s Stem Cells?

January 21st, 2011 01:31 admin View Comments

Talk about early intervention. One day, a fetus with a genetic disease may be able to get treatment before it even leaves the womb–and that treatment will come in the form of an extra gift from mom. While this scenario will only come to pass if new mouse research can be translated to humans, the finding are exciting.

The new work solves a medical mystery. When researchers realized they could diagnose a fetus with certain genetic illnesses as early as the first trimester, they plunged into the search for in utero treatments. Ailments like sickle cell anemia and some immune disorders might be treatable with blood stem cells taken from a donor’s bone marrow, researchers thought: the transplanted cells would multiply and populate the fetus’s bone marrow with healthy blood-forming cells, and the fetus’s immature immune system wouldn’t reject the foreign entities. But when researchers tried such transplants, they didn’t work.

“The fact that fetal stem cell transplantation has not been very successful has been puzzling, especially given the widely accepted dogma that the immature fetal immune system can adapt to tolerate foreign substances,†said co-senior author Qizhi Tang…. “The surprising finding in our study is that the mother’s immune system is to blame.†[press release]

The research team behind the current study, published in The Journal of Clinical Investigation, realized that the mother’s immune system was rejecting the transplants. They figured it out by examining the blood of a fetal mouse, and determining that up to 10 percent of the blood cells came from the mother–a surprisingly high figure. Then they monitored the blood of the mouse fetus during a stem cell transplant, and watched maternal immune cells rush to the transplant site. When they tried the procedure again with mouse moms who lacked the immune T-cells, the transplant worked.

Once they’d figured out the problem, it was easy to find the solution. The researchers harvested blood stem cells from the mouse mom and transplanted them into the fetus, and watched as the cells successfully settled down in the fetus.

“This research is really exciting because it offers us a straightforward, elegant solution that makes fetal stem cell transplantation a reachable goal,” said senior author Tippi MacKenzie at the University of California, San Francisco. [AFP]

But there’s still a long way to go before these mouse results can help humans.

“The critical question is how this applies to large animals and humans,” says Alan Flake, a pediatric surgeon and the director of the Center for Fetal Research at the Children’s Hospital of Philadelphia. Part of the issue with humans is that even when adult stem cells do survive in the fetus, it’s difficult for them to compete with the resident fetal stem cells, which can proliferate much more rapidly. [Technology Review]

To answer such questions, the research team will keep studying the interactions between the mother’s immune system and her fetus. They also hope to try the improved transplant procedure on monkeys.

Image: iStockphoto

Source: Could a Fetus’s Genetic Disorder Be Cured by Mom’s Stem Cells?

Blood Test Scores High on Detecting Down Syndrome

January 14th, 2011 01:34 admin View Comments

Not everybody is a big fan of being poked with needles to have their blood drawn. But from a medical perspective, blood tests are far less invasive and carry less potential for harm than other diagnostic tools. That’s why medical researchers are increasingly hunting for reliable blood tests for serious diseases, like the experimental Alzheimer’s disease test we covered last week. And this week, researchers report progress on assessing a new condition: a promising blood test for determining Down syndrome in a fetus.

The technique involves a blood test for the mother and an ultrasound for the baby. From the combined results, doctors can estimate the chance that the baby has Down’s. [CBS News]

Down syndrome happens when a baby has an extra copy of chromosome 21. Because the fetus’ DNA can cross over into the plasma of the mother, doctors can seek out the extra chromosome in a blood sample taken from the mother.

The researchers reporting in the British Medical Journal say that in a pool of 753 women, their tests had no false negatives. It accurately found all 86 fetuses with Down (The women selected were all at high risk for down in their fetus; the prevalence among the general public is only about 1 in 800). That’s a larger pool of women sampled than in similar research we covered in 2008, and with a higher success rate. The test is not perfect, though: It also identified false positives for Down in 2 percent of the fetuses that did not have the syndrome, which is why even a test more accurate than this one must have a backup to verify positive results.

The false positive rate could be higher in lower-risk women, which means that any positive test result might still need to be verified with a definitive result — a drawing of amniotic fluid to look at the fetus’s chromosomes themselves — before a woman makes a decision about whether to continue the pregnancy. [Boston Globe]

A blood for Down syndrome would be hugely welcome:

Currently, women in the United States are offered a blood test combined with an ultrasound test — called the combined test — to assess the risk of Down syndrome in pregnancy. The combined test still leaves an estimated 3% to 5% of women in need of invasive testing. [Los Angeles Times]

The invasive testing for Down often includes amniocentesis—drawing amniotic fluid for testing. That method carries with it an approximately 1 percent chance for miscarriage.

Image: iStockphoto

Source: Blood Test Scores High on Detecting Down Syndrome

From a Pregnant Woman’s Blood Sample, Researchers Determine Baby’s Genome

December 9th, 2010 12:25 admin View Comments

pregnant-cartoonIn a remarkable medical feat, researchers used a blood sample from a pregnant woman to work out the entire genome of her unborn fetus. The technique, published in the journal Science Translational Medicine, could provide a safer and less invasive way to check a fetus for fatal genetic mutations.

Currently, determining a fetus’s genome requires either amniocentesis, in which a needle is inserted through the mother’s abdomen into the amniotic sac, or chorionic villus sampling, in which a piece of placenta is removed. But both techniques carry a small risk to the baby, and are reserved for cases when there is an increased risk of genetic defects.

“The major advantage of the technique in this paper is that there’s no risk of miscarriage,” said Dr. Diana W. Bianchi, a reproductive geneticist at Tufts University who called the work a “technological tour de force.” Amniocentesis and CVS testing carry about a 1% risk of miscarriage, she said. [LA Times]

The new technique sequences the fetal genome from fragments present in the mother’s blood. In the late 1990s researchers discovered that fragments of fetal DNA are present in maternal plasma, presumably because the DNA gets broken down and crosses over the placental barrier.

In the years since, researchers have evaluated this DNA to detect many genetic and chromosomal problems in the fetus. But until now, researchers have focused on a single disease or genetic characteristic. [WebMD Health News]

Lead researcher Dennis Lo thought it should be possible to piece together the child’s entire genome from these fragments. But it wasn’t an easy task, since only 10 percent of the DNA present in the plasma is fetal–the rest belongs to the mother.

The fetal DNA was broken up into tiny pieces of about 150 base pairs each; a complete genome contains about 3 billion base pairs. “It’s like trying to assemble a jigsaw puzzle with millions of DNA molecules,” Lo said. [LA Times]

Lo tested his approach with a couple who were both carriers of beta-thalassemia mutations. If they had both passed on the mutation, their child would have the potentially fatal disease. Lo started by sequencing both the mother and father’s genomes. The researchers could then pick out the father’s genetic contribution to the fetal DNA in the maternal blood, since the father and mother’s genomes are different. The more difficult part was determining the fetal DNA that had been inherited from (and is genetically identical to) the mother, via one of her two sets of chromosomes.

“The deciphering of the part that the fetus had inherited from its mother was technically more challenging,” Lo says. “This was because the fetal DNA was surrounded by an ocean of DNA that the mother had released from her own cells.” [WebMD Health News]

To figure out which genes were inherited from the mother, the researchers checked the ratio of the mother’s two copies of DNA in the plasma. Whichever sequence the ratio was skewed toward would be the inherited sequence (since it would have extra copies from the fetus). The end result: The researchers discovered that the fetus had inherited the mutation from its father, but not its mother. It would be a carrier, but not suffer from the disease.

Because of the need to completely sequence both parents’ genomes, fetal whole-genome screening is prohibitively expensive. Scanning of particular gene regions, where there are known fatal mutations, could be much cheaper.

“We’re about a factor of 100 away from commercial capability, but that will change,” says Charles Cantor, one of the co-authors of the study. [Nature News]

Image: flickr / raebrune

Source: From a Pregnant Woman’s Blood Sample, Researchers Determine Baby’s Genome

New Report Says a Fetus Can’t Feel Pain Before 24 Weeks

June 25th, 2010 06:05 admin View Comments

24weeksIn a development that’s certain to stir passions in the abortion debate, the Royal College of Obstetricians and Gynaecologists in the UK published a report today on “fetal awareness.” The group states, citing a review of current research, that human fetuses cannot feel pain before 24 weeks.

The group’s reasoning, as described in a press release, is based on these points:

-The fetus cannot feel pain before 24 weeks because the connections in the fetal brain are not fully formed
-The fetus, while in the chemical environment of the womb, is in a state of induced sleep and is unconscious
-Because the 24 week-old fetus has no awareness nor can it feel pain, the use of analgesia is of no benefit
-More research is needed into the short and long-term effects of the use of fetal analgesia post-24 weeks [Royal College of Obstetricians and Gynaecologists]

This is certainly not the first debate over whether a fetus can feel pain. Fetal surgeries have led doctors to ask this question, as they determined whether anesthesia was appropriate and at what stage in development. As summarized in a 2008 New York Times Magazine article, researchers have looked at fetal flinch responses, heart rate, and levels of stress hormones. But any metric has remained controversial. Take stress hormones, for example. Do you say that any fetus that can release these hormones feels pain? Or do you wait until it develops the nervous system to register those hormones? Or do you say that an undeveloped nervous system makes the fetus more susceptible to pain, since it hasn’t developed the system to suppress it?

In April, Kanwaljeet Anand, director of the Pain Neurobiology Laboratory at the University of Tennessee Health Science Center in Memphis and an often-quoted researcher in the debate, described some of the issues:

When a fetus of that age [18 to 20 weeks] gets a blood transfusion, for example, changes in heart rate and blood pressure accompany shifts in circulation and spikes in stress hormones. A morphine-like drug calms all of those responses down. “The die-hards will say these are all reflexes,” Anand said. But new evidence, he argued, suggests that the very young brain is developed enough in the right places to take in those sensations and translate them into pain. [Discovery News]

The Royal College of Obstetricians and Gynaecologists’ report differs from Anand’s assessment, and argues that fetuses younger than 24 weeks don’t have the brain connections to register pain, and if they could register the chemical signals, they couldn’t make out what they mean.

The report on pain perception says: “It was apparent that connections from the periphery to the cortex are not intact before 24 weeks of gestation and, as most neuroscientists believe that the cortex is necessary for pain perception, it can be concluded that the foetus cannot experience pain in any sense prior to this gestation.” Even after 24 weeks, “it is difficult to say that the foetus experiences pain because this, like all other experiences, develops post-natally along with memory and other learned behaviours”. [The Gaurdian]

Understanding when a fetus can feel pain has implications for abortion laws, and groups on both side of the debate have weighed in on today’s reports.

As the BBC reports, those in the United Kingdom question the reports’ implications for the 1967 Abortion Act, which covers all parts of the UK apart from Northern Ireland, and caps legal abortion at 24 weeks (with some exceptions, regarding dangers to the life of the pregnant woman or evidence of serious fetal abnormality). Some activists had campaigned to reduce that timeframe, but UK government representatives have said that there are currently no plans to change the act.

A Downing Street spokeswoman said: “The Prime Minister’s view is that he will be led by the science.” She added: “At the moment there are no plans to change the policy.” [BBC]

Image: flickr / Chris Denbow

Source: New Report Says a Fetus Can’t Feel Pain Before 24 Weeks

Studies Prove BPA Can Cross Placenta To Fetuses

June 8th, 2010 06:53 admin View Comments

Totes McGotes writes “From canned food to plastic bottles, Bisphenol-A seems to be cropping up everywhere, and now two new studies show that BPA freely crosses the placenta from pregnant mother to fetus. Plus, the research found that chemical transformations occur in the fetus allowing inactive BPA to be converted to the active form.”

Source: Studies Prove BPA Can Cross Placenta To Fetuses