Thursday, October 15, 2015

The Cords Not Cut After Birth Of a Child


A team of pathologists Leiden University Medical Center in the Netherlands recently carried out an experiment that might seem doomed to failure.

They collected tissue from 26 women who had died during or just after pregnancy. All of them had been carrying sons. The pathologists then stained the samples to check for Y chromosomes.

The scientists were looking for male cells in female bodies. And their search was successful.

As reported in the journal Molecular Human Reproduction recently, the researchers found male cells in every female organ they studied: brains, hearts, kidneys and others.

In the 1990s, scientists found the first clues that cells from both sons and daughters can escape from the uterus and spread through a mother’s body. They called the phenomenon fetal microchimerism, after the chimera, a monster from Greek mythology that was part lion, goat and dragon.

But fetal cells don’t just drift passively. Studies of female mice show that fetal cells that end up in their hearts develop into cardiac tissue.

“They’re becoming beating heart cells,” said Dr. J. Lee Nelson, an expert on microchimerism at the Fred Hutchinson Cancer Research Center in Seattle.

The new study suggests that women almost always acquire fetal cells each time they are pregnant.
They have been detected as early as seven weeks into a pregnancy. In later layers, the cells may disappear, but sometimes the cells settle in for a lifetime.

In a 2012 study, Dr. Nelson and her colleagues examined the brains of 59 deceased older women and found Y chromosomes in 63 percent of them. (Many studies on fetal microchimerism focus on the cells left behind by sons, because they are easier to distinguish from the cells of their mother.)

Experts now believe that microchimerism is far from rare.

“Most of us think that it’s very common, if not universal,” Dr. Nelson said. But it remains quite mysterious.

In recent years, researchers have found many clues suggesting that microchimerism can effect a woman’s health. Tumors may be loaded with fetal cells, for example, suggesting that they might help drive cancer. Yet other studies have suggested that fetal microchimerism protects women against the disease.

“In each instance of a disease, it seems like there is this paradox,” said Amy M.Boddy, a postdoctoral fellow at Arizona State University.

Fetal microchimerism has been found in a number of mammal species, including dogs, mice and cows.

It’s likely that fetal cells have been a part of maternal life for tens of millions of years.

Microchimerism is something that humans have been evolving with since before we were humans, “said Melissa Wilson Sayres, a biologist at Arizona State.

During that time, fetal cells could have evolved into more than just bystanders. Writing in the journal  in August, Dr. Boddy, Dr.Sayres and their colleagues suggested that fetal cells may produce chemicals that influence the mother’s biology, allowing fetuses to manipulate her from within.

Some cells may help maintain the health of the mother- For example, by healing wounds. But there is also an evolutionary conflict of interest between mothers and their young.

A mother’s reproductive success depends on the total number of children she raises to adulthood over the course of her life. Devoting too many resources to a single child may leave her too frail to care for later children.

If a child can somehow coax its mother to provide more resources, on the other hand, he or she may be more likely to survive to adulthood and reproduce. Fetal cells may let children manipulate their mothers to this end, Dr. Sayres and her colleagues suggest.

Fetal cells are frequently found in breast tissue, even in milk, for instance. The researchers argue that children might thrive more if their fetal cells drove up milk production.

Mothers also nurture their babies with body heat. The thyroid gland, located in the neck, acts like a thermostat, and fetal cells in the thyroid gland in theory could cause mothers to generate more heat than they would otherwise.

This biological tension might help explain how fetal microchimerism sometimes causes harm to a mother. It may simply be an occasional side effect of the cells ‘manipulations.

There are some clues that mothers, too, pull hard in this evolutionary tug of war. The immune system kicks into high gear after giving birth, possibly to clear away left-over fetal cells. This defense may pose its own risks: Women with auto immune disorders such as rheumatoid arthritis can have relapses after pregnancy.

Some straightforward experiments could put all of these ideas to the test. Scientists could look at which genes become active in fetal cells in different parts of the body, for example. They could then see how the activity of the genes influenced a mother’s physiology, such as the production of milk.

If the preliminary results hold up, Dr. Boddy and her colleagues suggest scientists should consider how fetal cells in the brain might influence women’s behavior.

“It’s the most exciting part, but it’s the part where there’s the least research at the moment,” said Athena Aktipis, a psychologist at Arizona State and an author of the Bioessays article.” There may be a role of microchimerism in postpartum mental health.”

Dr. Nelson, who was not involved in the new paper, said that is raised a lot of ideas worth pursuing. “It’s going to be interesting to see how the data coming in over the next several years stacks up,” she said.

Taken from TODAY Saturday Edition, The New York Times International Weekly, October 3, 2015

Wednesday, July 15, 2015

Food May Be Too Clean For Our Gut’s Good Health

Color-enhanced scanning electron micrograph sh...
Color-enhanced scanning electron micrograph showing Salmonella typhimurium (red) invading cultured human cells (Photo credit: Wikipedia)

With the recent recalls of millions of liters of ice cream as well as several tons of hummus, pine nuts, frozen vegetables and various meat products, you might think the American food supply is an unholy mess. It’s not. It’s arguably the safest in the world.

Yet despite continually improving processing methods and quality controls, the number of cases of food-borne illness has remained high since the 1990s, with the incidence of people getting sick from some pathogens increasing.

Some experts wonder if we’ve reached a point of diminishing returns in food safety-whether our food could perhaps be too clean.

Industrial food sanitation practices – along with home cooks’ antibacterial veggie washes, chlorine bleach kitchen cleaners and sterilization cycle dishwashers – kill off so-called good bacteria naturally found in foods that bolster our health. Moreover, eliminating bad or pathogenic bacteria means we may not be exposed to the small doses that could inoculate us against intestinal crises.

“No one is saying you need to eat a peck of dirt before you die to be healthy,” said Jeffrey T. Le Jeune, a professor and head of the food animal research program at Ohio State University in Wooster. “But there is a line somewhere when it comes to cleanliness. We just don’t know where it is.”

The theory that there might be such a thing as “too clean” food stems from the hygiene hypothesis, which has been gaining traction over the last decade. It holds that our modern germaphobic ways may be making us sick by harming our microbiome, which is the system made up of all the microbes-bacteria, viruses, fungi, mites-that live in and on human bodies.

A result of a diminished microbiome is an immune system that gets bored, spoiling for a fight and apt to react to harmless substances ad even attack the body’s own tissues. This could explain the increasing incidence of allergies and autoimmune disorders such as asthma, rheumatoid arthritis and inflammatory bowel disease.

There is also the suggestion that a diminished microbiome disrupts hormones that regulate hunger, which can cause obesity.

When it comes to food-borne illness, the idea is that fewer good bacteria in your gut means there is less competition to prevent colonization of the bad microbes, leading to more frequent and severe bouts of illness. Moreover, an underutilized immune system may lose its ability to discriminate between friend and foe, so it may marshal its defenses inappropriately (against gluten, for example) or not at all.

Animal experiments have lent some credence to the theory. Researchers at Texas Tech University in Lubbock have found that guinea pigs fed less virulent strains of listeria are less likely to get sick or die when later fed a more pathogenic strain. And anyone who has visited a country with less than rigorous sanitation knows the locals don’t get sick from foods that can cause tourists days of toilet-bound torment.

“We have these tantalizing bits of evidence that to my mind provide pretty good support for the hygiene hypothesis, in terms of food-borne illness,” said Guy Loneragan, a professor of food safety and public health at Texas Tech.

This is not to say we’d be better off if chicken producers eased up on the salmonella inspections, we ate recalled ice cream sandwiches and didn’t rinse our produce. But it raises questions about whether it might be advisable to eradicate microbes more selectively.

Taken from TODAY Saturday Edition, The New York Times International Weekly, May 23, 2015