© Romeo Gacad/AFP/Getty ImagesChildren whose mothers were exposed to certain pesticides during pregnancy are at a slightly elevated risk of developing attention problems, a new study shows.
Doctors have long known that diabetics are prone to getting infections, but they couldn't say with any certainty why these patients are so vulnerable to microbial invaders.
Now British researchers think they have solved the mystery. They conducted a series of lab experiments that suggest elevated levels of glucose in the bloodstream - a hallmark of diabetes - inhibit the ability of the body's immune system to detect and fight bacterial and fungal infections.
Diabetes occurs when the pancreas doesn't secrete enough insulin or the body's cells don't use insulin properly. Insulin is the hormone that clears glucose (sugar) from the blood and moves it to cells where it is used for energy. As a result, diabetics often have much higher blood levels of glucose than normal.
For their study, the research team, led by Daniel Mitchell, an associate professor and biochemist at the University of Warwick, first analyzed the similarities between the chemical structure of glucose and two other sugars called mannose and fucose.
These sugars are found on the surfaces of certain bacteria and fungi. Under normal circumstances, specialized cells of the immune system use these sugars as target sites and will latch onto them to begin their counteraction. In other words, mannose and fucose serve as red flags that give away the presence of potentially harmful microbes, alerting the immune system to get in high gear.
Using tissue samples, the researchers tried to replicate what happens when the bloodstream is flooded with too much glucose. "When we introduced increased amounts of glucose, we found that the normal binding of an immune receptor starts to fail," Dr. Mitchell said. And some immune cells begin attaching to glucose, rather than the foreign invaders.
"It really is just a case of the glucose resembling parts of the bacterial structure," he said. "You could use the analogy that the immune cells have become blind, or their ability to sense the pathogens diminishes," said Dr. Mitchell, whose study was published in the journal Immunobiology.
If additional research confirms that elevated glucose does indeed hinder the immune system, researchers may able to develop new treatments - and possibly medications - to help bolster the body's defences against infections, he said. But those developments are still a long way off.
In the meantime, the study helps drive home the message that it's important for diabetics to keep their blood glucose levels under control through lifestyle factors including a proper diet. After all, controlling blood glucose is considered to be paramount in preventing long-term complications of diabetes such as heart disease, nerve damage and kidney disease.
Early exposure
Children whose mothers were exposed to certain pesticides during pregnancy are at a slightly elevated risk of developing attention problems, a new study shows.
The researchers collected urine samples from a group of pregnant women to check for exposure to organophosphate pesticides, which are widely used in agriculture. Years later, the offspring were tested for signs of decreased attention. The mothers were also asked questions about the behavior of their children.
"At age 5, we saw an association between in utero exposure [to pesticides] and child performance on these tests as well as other measures of attention problems," said lead researcher Brenda Eskenazi, director of the Center for Children's Environmental Health Research at the University of California, Berkley.
The researchers stopped short of saying the children had either attention deficit disorder or attention deficit hyperactivity disorder. Dr. Eskenazi said that additional testing would have been needed to confirm a clinical diagnosis of ADD or ADHD.
Still, the current study, published in the journal Environmental Health Perspectives, and other recent studies point to a link between pesticides and some cases of attention problems. "ADHD is multifactoral," she said. "There are going to be many, many causes for attention problems in children. What we are showing is one."
In a separate study, published in the same edition of the journal, Dr. Eskenazi found that some people carry a gene that could increase their vulnerability to organophosphate pesticides, which are known to affect the central nervous system. And, in particular, the genetic trait makes it harder to excrete the chemical from the body. "It may mean the toxic effects are greater for them than other children," she speculated.
Dr. Eskenazi noted that food represents a significant source of pesticide exposure for the general population. "I would recommend thoroughly washing fruits and vegetables before eating them, especially if you're pregnant."
But she also stressed that pregnant women shouldn't shy away from these foods out of fear of pesticides. The health of their offspring depends upon eating a well-balance diet - and that includes an ample supply of fruits and veggies, she said. The pesticides "are pretty water-soluble and if you use a little bit of soap they should wash off."
A case for exercise
When it comes to weight loss, exercise apparently does more than just burn off calories. It can also help dampen your appetite, according to Brazilian researchers.
In a study involving obese rodents, they found that exercise helps to restore the sensitivity of neurons in the brain involved in the control of satiety (or feeling full), which, in turn, contributes to reduced food consumption - and consequently weight loss.
The researchers noted that excessive fat consumption, over an extended period of time, can lead to a disruption in the normal process of appetite control and can contribute to overeating. Exercise gets it back on track, suggests the study, published in the journal PLoS Biology.
"Thus, exercise leads to a decrease in food intake and an increase in energy expenditure," said lead researcher Jose Carvalheira of the University of Campinas.
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