Archives for posts with tag: fetus

Greenwire: Prenatal exposures prompt EPA to re-examine chemical regulations.

U.S. EPA regulators convened with scientists last month to discuss how to design regulations for chemicals based on emerging science that connects exposures during pregnancy with disease much later in life.

A mother exchanges with her child in the womb chemicals that have remained constant for much of human evolution. They dictate which genes will be turned on and off in the child, which proteins the child will make in his body and how much of them.

New research, in a field called epigenetics, now suggests that these changes, made during the earliest part of gestation, could spell out the child’s longer-term medical record. It could determine his propensity for mood swings, his tendency to gain weight into the realms of obesity, his risk of developing cardiovascular disease or cancer when he hits 50, and his propensity of passing on his genes to his children.

The idea is that the child adapts to environmental cues in the womb that will reflect the chemical composition of the world, thus conferring a Darwinian fitness advantage.

The mix of chemicals a fetus is exposed to has exploded in the past 200 years, heralded by the Industrial Revolution. Technology has outstripped evolution, said Robert Chapin, senior research fellow in drug safety research and development at Pfizer Inc. People were suddenly surrounded by particulate matter from cars, coal-plant emissions, metals, organic molecules from hand sanitizers, body lotions and other chemicals, some of which could cross into the placenta and merge into the child’s aqueous world.

Some, such as folic acid, were intentionally given to moms as beneficial; others such as bisphenol A became common in the modern environment and had the ability to mimic hormones that are naturally present in humans. Yet others, such as arsenic and tin, are naturally present in some places.

Scientists now suspect that the altered chemical cues during the critical windows of pregnancy — at stages when gender is still developing and the human is little more than a collection of cells — could trigger pathways that manifest as disease well into adulthood.

More . . .

From the Milwaukee Journal Sentinel:

Scientists are learning that health is the function of genes and environment. The work of Milwaukee-based researchers suggests that this principle also applies to the health of a growing fetus and a premature infant.

Michael Laiosa, assistant professor at the University of Wisconsin-Milwaukee School of Public Health, and neonatologist Venkatesh Sampath, an assistant professor of pediatrics at the Medical College of Wisconsin, want to understand how genetics and the environment affect the health of humans during the most vulnerable stages of development.

In Milwaukee, there were 807 infant and fetal deaths between 2005 and 2008, according to the city’s Fetal Infant Mortality Review. A disproportionate number were African-American. Of the 499 who were not stillborn, nearly 54% died from complications of being born too soon.

During gestation and early in life, infants reach developmental milestones at a rapid pace. But in the presence of a dysfunctional gene, toxic exposures, or a combination of both, development is prone to error.

According to Sampath, who is collaborating with colleague Ronald Hines, professor of pharmacology and toxicology at the Medical College, some premature babies may be more susceptible to necrotizing enterocolitis, or NEC, a leading cause of mortality and disability in very low birth-weight preterm infants weighing less than 3½ pounds.

What causes this disease is unknown, but doctors believe that an underdeveloped immune system or intestinal lining may leave a preterm infant’s bowel vulnerable to infection or injury. What results is severe inflammation, which can lead to a deadly infection. Between 25% and 40% of babies afflicted with NEC die.

In their recent study published in the Journal of Surgical Research, Sampath and Hines detected a variant of a gene called NFKB1, differing slightly from the normal form, which is involved in mounting an immune response. Investigators said premature infants with a genetic variant may be at higher risk for developing the potentially fatal NEC.

In the study of 270 very low birth-weight preterm infants, investigators reported that of the 15 infants diagnosed with NEC, all had at least one copy of the defective gene and were disproportionately African-American.

“African-American infants run a higher risk of NEC,” Sampath said of the study findings.

The defective gene turned up in 65% of infants not diagnosed with NEC, suggesting that other factors are involved in the onset of the disease. Sampath said it may be the presence of a particular bacteria, poor blood flow to the intestines, or another malfunctioning gene.

Infants with NEC experience pain, according to Sampath. “It’s a nasty disease,” he said.

Sampath added that those infants who survive a severe case of NEC are at greater risk for developmental delays and cerebral palsy.

Jackie Sevallius, supervisor of the newborn intensive care center at Wheaton Franciscan-St. Joseph hospital in Milwaukee, cares for infants with NEC and said signs of pain in a preterm infant are often subtle and manifest as changes in blood pressure, heart rate, breathing and color.

Very low birth-weight babies unable to muster a cry will express their pain through a facial grimace, said Sevallius.

Whether the variant gene can be used as a marker of NEC susceptibility in preterm infants is not yet clear.

“At this stage, it is preliminary, which means it needs to be addressed in a large amount of patients before we can tell for sure. It is worth further digging,” Sampath said.

David Hackam, professor of surgery at the University of Pittsburgh School of Medicine, said Sampath’s studies may one day offer doctors a way to screen premature infants for increased risk for NEC. Early screening could lead to earlier diagnosis and treatment, he said. Current treatments include changes in feeding, antibiotics and surgery. “These studies make a strong case for further genetic studies to understand this complex and devastating disorder,” Hackam said.

Sampath said he hopes to explore whether this genetic variant can be used to predict other diseases of prematurity.

Developmental origins

How the outside world leaves its imprint on a growing fetus and potentially affects health later in life is an emerging field of research. A pregnant woman’s lifestyle choices, nutrition, exposure to toxicants – and even stress – may modify when and how genes are expressed during the course of fetal development.

More.

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