More bacteria in the air than previously thought

Thousands of bacteria that change with the weather drift in the atmosphere

The air is a hostile place for bacteria. Often dry, lacking in nutrients and filled with deadly ultraviolet radiation, the atmosphere would seem to be the last place a bacteria would want to find itself. Yet, a new genetic census of some air samples from Austin and San Antonio, Tex., finds that as many as 2,000 different kinds of bacteria may be present in the air we breathe on any given day.

Microbial ecologist Gary Andersen of Lawrence Berkeley National Laboratory and his colleagues collected air samples in the two Texas cities over a period of 17 weeks, starting in 2003. They then used a specially designed microarray--a small chip roughly the size of a quarter that carries probes to detect specific genetic information--to search for a gene involved in the making of a protein (16S) that is found in many bacteria. "We designed a 500,000-probe array to identify up to about 9,000 different groups of bacterial and archaean organisms," Andersen explains. "It looks at the differences in the 16S sequence to identify a specific type of prokaryotic organism."

In the air samples, the researchers uncovered at least 1,800 different types of microbes, including those such as the diarrhea-causing Arcobacter and ulcer-inducing Heliobacter genera that can be dangerous to human health. Previous efforts to determine bacteria counts in the atmosphere had relied on culturing the air to see what grew. "Over 90 percent you can't recover even though it was not only present but viable," Andersen notes. "It's just something about the physiological state it gets in; when it's not in rich media, it has a different physiology."

This puts the diversity of bacteria in the air on par with the diversity of bacteria in the soil, a fertile environment for such life-forms. In fact, there is a large crossover between the bacteria in the air of a city and the bacteria in its soil. The ecologists found that airborne bacteria were broadly the same in Austin and San Antonio as well, and varied more depending on the weather than any other factor.

The most common bacteria included those that thrive in hay fields and deteriorating exterior paint, according to the paper published online December 18 in Proceedings of the National Academy of Sciences USA. "We were surprised at how many different types of sequences we were seeing," Andersen adds. "Obscure phyla, like TM7, which have been seen in soil and gum tissue; hot springs type organisms; and bacteria from sewage treatment plants."

The census provides a background for ongoing efforts by the U.S. Department of Homeland Security to monitor city air for potential bioterrorism attacks as well as fills in a gaping hole in the understanding of where bacteria persist. For example, storms of Saharan dust--and their attendant microbes--have been linked to local meningitis outbreaks and tracked across the Pacific to coral deaths and an increase in childhood asthma in the Caribbean. "It's important to do a microbial census to see what's in the air we breathe. I believe it's going to change as the climate changes," Andersen says. "We may see very different populations of microbes in the air and that may have some health implications."

The air is now being tested in at least 30 U.S. cities and Andersen hopes the effort will be broadened. "How is it in the middle of the oceans?" he asks. "Is it just what's coming up from the sea's surface or is it a long-range dispersal of organisms?" Whatever the case, fresh, clean, bacteria-free air is rarer than previously thought.

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Congenital heart disease increasingly more common in adults, children

American Heart Association rapid access journal report

The prevalence of congenital heart disease (CHD) has increased strikingly in adults and children in a new population study, researchers reported in Circulation: Journal of the American Heart Association.

Severe CHD has risen in adults by 85 percent and 22 percent in children during the 15-year study (1985-2000). Congenital heart defects are structural problems arising from abnormal formation of the heart or major blood vessels near the heart that occurs before birth. Most heart defects either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal way.

"This is the first study to measure the changing number of patients in a North American population during a period of major progress in the management of CHD," said Ariane J. Marelli, M.D., lead author of the study and director of the McGill Adult Unit for Congenital Heart Disease Excellence at McGill University in Montreal, Quebec, Canada.

The study measured prevalence, age and proportion of adults relative to children at four time points: 1985, 1990, 1995 and 2000, and analyzed the Quebec administrative databases recorded for the general population where access to health care is universal. Quebec accounts for 25 percent of Canada's population.

"This is the largest population study of CHD to have been performed in North America," Marelli said. "There is no reason to believe that the predominantly Caucasian population of Quebec and Canada is different from the United States."

Extrapolating the study findings to the U.S. population, Marelli estimated 1.8 million Americans had CHD in 2000 and that this number is increasing and will have implications for women, pregnancy and genetics. She estimated about 900,000 adults and 900,000 children had CHD.

In 2000, the study indicated that one of every 85 children had CHD and one of 250 adults had CHD.

"For comparison purposes, cystic fibrosis occurs in one of 4,500 live births, so there are 45 times more children with CHD than children with cystic fibrosis and most of these children are now becoming adults," Marelli said.

Furthermore, more adults have had CHD than children since 1985, and a preponderance are women, the study found.

"Between 1985 and 2000, the group of patients that rose the most rapidly was adults with severe CHD, so, as of 2000, there were a nearly equal number of children and adults with severe CHD," Marelli said

The most significant increases in CHD were in adolescents (13 to 17 years old) and in young adults (18 to 25), according to the study. The median age of those with severe CHD increased markedly from 1985 to 2000. The median age in 1985 was 11 years compared to 17 years in 2000.

"CHD has been thought of as a disease of childhood, but it has become an important disease of adulthood as well," Marelli said. Researchers said the significant new data in the study reflects advances in the diagnosis and surgical treatment of CHD.

"Since the mid-1980s, the advent of cardiac ultrasound has improved the diagnosis of CHD," Marelli said. "This technique can be used to detect CHD beyond the first year of life. Advances in corrective pediatric cardiac surgery have made an impact, enabling children with CHD to live longer." Marelli considers CHD a major public health problem in North America that is largely under-recognized.

"The increasing prevalence of CHD means these children will live longer and acquire other forms of heart disease," Marelli said. "We need to increase public awareness for congenital heart disease in order to be able to better care for the increasing number of young people with heart disease."

Vision Loss Can Be Prevented in People With Diabetes

The millions of Americans afflicted with Type 1 and 2 Diabetes face many potential complications, including: heart and kidney disease; nerve damage and stroke; foot and skin problems; and gastrointestinal disorders and hypoglycemia.

Another major complication, affecting up to 24,000 new people per year, is permanent blindness due to diabetic retinopathy, a degenerative disease of the retina (the sensitive area at the back of the eye). Overall, diabetic retinopathy affects 5.3 million Americans 18 and older.

But there’s hope. The American Academy of Ophthalmology wants Americans to know that even though diabetes is the leading cause of new cases of blindness, vision loss can be prevented if the disease is diagnosed and treated in time.

“Only 50 to 60 percent of those with diabetes get the recommended yearly eye examinations,” said Jose S. Pulido, MD, Academy clinical correspondent and professor of ophthalmology at the Mayo Clinic in Rochester, Minn. “Studies show effective treatments, including an annual dilated eye exam, can reduce severe vision loss by up to 94 percent.”

According to the American Diabetes Association, there are 20.8 million people in the United States, or 7 percent of the population, who have diabetes. While an estimated 14.6 million have been diagnosed, 6.2 million people (or nearly one-third) are unaware that they have the disease.

“This is a tragedy waiting to happen because people who are unaware they have the disease are at a substantially greater risk for vision loss and other complications,” said Dr. Pulido. “The first step in preventing complications is finding out if you have the disease. It’s important for all healthy adults over the age of 45 to have a blood sugar test once every three years.”

Dr. Pulido said that the longer a person has diabetes, the greater the risk for developing diabetic retinopathy.

“Diabetic retinopathy does not only affect people who have had diabetes for many years, it can also appear within the first year or two after the onset of the disease,” he said. “For some people, diabetic retinopathy is one of the first signs of the disease.”

Anatomy of Diabetic Retinopathy High blood sugar levels weaken blood vessels in the eye's retina, causing them to leak blood or fluid. This causes the retina to swell and can lead to vision loss.

Blood sugar fluctuations can also promote growth of new, fragile blood vessels on the retina, which can easily break and leak blood into the vitreous (the clear, jelly-like substance that fills the center of the eye). This can blur vision and lead to permanent blindness.

In its earliest stages diabetic retinopathy may not affect vision, but over time it can cause vision loss and even blindness in both eyes.

What are the Signs of Diabetic Retinopathy? “Fluctuations in blood sugar levels can temporarily affect vision, so it's sometimes difficult to know if a serious eye problem is developing," said Dr. Pulido. "That's one of the reasons strict control of your blood sugar is so important. If you notice a vision change in one eye, a change that lasts more than a day or two, or changes not associated with fluctuations in blood sugar, contact your Eye M.D. immediately."

Other ways to reduce the risk of eye disease:

Keep your blood glucose level as close to normal as possible through diet, exercise and, if needed, medication

Keep your blood pressure under control

Keep your cholesterol levels low

Don’t smoke

Make sure your hemoglobin A1c levels (a measure of good blood sugar control) are measured at least every four months and are less than 7.1.

Diabetic Retinopathy: A New Hope

Although incurable, diabetic retinopathy can be treated to retard its onset and progression. There’s hope for the development of new pharmacological treatments that would not require invasive laser surgery. These treatments might even restore the vision that the disease destroys.

These potential treatments signal a move away from laser photocoagulation to drugs injected into the eye, as well as oral treatments.

Many of these drugs block the pathways that contribute to the vascular disruptions that characterize diabetic retinopathy. Specifically, they aim to inhibit the growth of new blood vessels or the activity of proteins in the nerve cells of the retina.

These treatments hold promise of intervention at earlier, non-sight-threatening stages, but they will require renewed emphasis on early detection. The newest and best treatments will be most effective only when the underlying disease—diabetes—is under control.   

Vegetables Lower Blood Pressure

WebMD

Scientists in Sweden have found a type of nutrient in vegetables that may help keep blood pressure in check.

And it could explain why the U.S. government-recommended DASH diet (Dietary Approaches to Stop Hypertension) has been proven to actually lower blood pressure rates within two weeks.

Dr. Eddie Weitzberg, professor of anesthesiology and intensive care at the Karolinska Institute in Stockholm, gave 17 young adults a dietary supplement of sodium nitrate. The nitrate is a compound found in foods such as spinach, beet root, and lettuce.

The subjects were given the nitrate (150 grams to 250 grams) for three days then a placebo for three days. Results showed that the average diastolic blood pressure (the bottom number in a blood pressure measurement) was 3.7 mm hg lower after the supplement.

The DASH diet, which advises those with high blood pressure to consume four to six fruits and four to six vegetables daily, reduces the diastolic blood pressure by an average of 3 mm hg.

“What this study suggests is that the well-known beneficial effects of vegetables on cardiovascular disease may at least partly depend on nitrate,” said Weitzberg.

The findings from the small study were published in the December issue of the New England Journal of Medicine.

While nitrate is currently considered to be “a substance that should be avoided or at least reduced in our drinking water and food” because it is believed to increase the risk of blood infections and cancer, the ingested pill version may be a path way for natural nitric oxide production within one’s own body.

Dr. Steven Nissan, chairman of cardiovascular medicine at the Cleveland Clinic countered that one would need to consume about half a pound of spinach a day to derive the benefits from the 250 gram supplement.

Still, “Everyone has been asking why this [the DASH] diet worked,” he said, adding that the study does provide evidence for the possible effect of the sodium nitrate in green, leafy vegetables.

Obesity linked to Bacteria

By Elizabeth Weise, USA TODAY

You are what your bacteria eat.

Two new studies show that there are different colonies of bacteria in the intestines of the obese than there are in the innards of the slim. The research, published in today's edition of the journal Nature, finds that bacteria in an overweight body are more efficient at extracting calories from food.

So what can a person do?

"Not everyone sitting down to a bowl of cereal will necessarily absorb the same number of calories from it," says Jeffrey Gordon, lead author of the papers and a professor of medicine at Washington University in St. Louis.

About two-thirds of adults, about 136 million Americans, are overweight or obese, the government says. These findings open up a new area of research, says Sam Klein, a study co-author and professor of gastroenterology at the university.

"It's not just your brain and your body fat and your body organs involved in your energy balance equation," he says. "It may also be the bugs that are in your body as well."

One study focused on mice, the other on humans. They found that in both man and rodent, a family of bacteria known as firmicutes were more plentiful in the obese than in the lean. Conversely, bacteria called bacteroidetes were less abundant than in normal-weight subjects.

The research showed that obese mice were more efficient than lean mice at harvesting calories from complex sugars found in fruits, vegetables and grains, and depositing those calories in fat — most likely because of the bacterial colonies.

And when they transplanted bacteria from obese and thin mice into mice raised in a sterile environment, those that got bacteria from the obese mice gained twice as much fat.

When obese people lost weight, virtually all the bacteroidetes increased, while the firmicute group shrank, Gordon says.

The bacteria inside us are a huge and mysterious part of life. "There are trillions of them, they outnumber the human cells in our bodies," Klein says. Gordon quips, "you never eat alone."