Friday, August 01, 2008

Study shows exposure to some types of air pollution raises blood pressure in some rats in some circumstances

My heading above is accurate. The original heading was: "Study shows exposure to bad air raises blood pressure"

The air people breathe while walking in the park, working in the garden or shopping downtown may be unhealthy enough to seriously spike their blood pressure, a new study suggests.

Cardiovascular researchers at The Ohio State University Medical Center are the first to report a direct link between air pollution and its impact on high blood pressure, or hypertension. If the results from these animal studies hold up, this could be important for human health. "We now have even more compelling evidence of the strong relationship between air pollution and cardiovascular disease," said Sanjay Rajagopalan, section director of vascular medicine at Ohio State's Medical Center and co-author of the study. This builds upon previous research from Rajagopalan's team published in the journals JAMA, Circulation and Inhalation Toxology.

Researchers exposed rats to levels of airborne pollutants that humans breathe everyday, noting the levels were still considerably below levels found in developing countries such as China and India, and in some parts of the U.S.

Researchers found that short-term exposure to air pollution, over a 10-week period, elevates blood pressure in those already predisposed to the condition. The results appear online and are scheduled for publication in an upcoming issue of Arteriosclerosis, Thrombosis, and Vascular Biology, a journal published by the American Heart Association. "Recent observational studies in humans suggest that within hours to days following exposure, blood pressure increases," Rajagopalan says.

In a highly-controlled experiment, hypertensive rats were placed in chambers and exposed to either particulate matter or filtered air for six hours a day, five days a week, over a period of 10 weeks. At week nine, researchers infused angiotensin II, another pollutant, into mini-pumps within the chambers and monitored responses in blood pressure over one week.

The air pollution level inside the chamber containing particulate matter was comparable to levels a commuter may be exposed to in urban areas with heavy traffic such as downtown Manhattan. "Pre-exposure to air pollution markedly increased blood pressure responses following infusion of angiotensin II," added Rajagopalan.

According to the U.S. Environmental Protection Agency (EPA), the four most common pollutants emitted into the air are particulate matter, ozone, nitrogen dioxide and sulfur dioxide. Air pollution is commonly the result of industrial emissions, coal burning, power plants and automobile exhaust. "This study provides guidance for the EPA to change pre-existing stringent standards in the effort to reduce air pollution," says Rajagopalan. "Our study also confirmed a need for a broader based approach, from the entire world, to influence policy development."

Qinghua Sun, first author of the study, will analyze vascular function in humans before and after the upcoming summer Olympics in Beijing, China. With stringent laws to ensure good quality during the games, it is anticipated that the air quality will improve significantly in and around Beijing. "We expect to find a tangible impact on vascular function and blood pressure because ultimately the only thing that will have changed is levels of air pollution," says Sun.


DNA discovery in schizophrenia

Those pesky genes again!

THREE studies of more than 60,000 people have identified a range of genetic abnormalities linked to schizophrenia, including missing sections of DNA. The discoveries represented a milestone in determining the genetic basis of the complex mental disorder which affects one in 100 Australians, scientists said.

Bryan Mowry, executive director of the Queensland Centre for Mental Health Research, and a co-author of one of the studies, said the findings could help determine the biological causes of the debilitating disease so new treatments could be developed. They could also eventually lead to tests for earlier diagnosis of the condition, which doctors can only identify now from symptoms including hallucinations and delusions. "Hopefully, that will be one of the outcomes," he said.

The study, in which Professor Mowry took part, included people with bipolar disorder, and the results suggested this condition had genetic risk factors in common with schizophrenia, he said. The three studies, published in the journals Nature and Nature Genetics, succeeded where smaller studies had failed because they looked at large numbers of people and searched right across the 3 billion letters of the human DNA code.

Two types of abnormalities were found: in single letters in the code, and in large chunks of DNA involving more than 100,000 letters, which were either missing or repeated in some people with the disease.

A team led by scientists at an Icelandic company, deCODE genetics, identified three genetic deletions which can occur spontaneously when eggs and sperm are created. These gaps in the DNA code were rare but increased the risk of schizophrenia between three- and 15-times.

The International Schizophrenia Consortium, involving researchers from 11 institutes in Europe and the US, also independently discovered two of these three deletions. They also found that people with schizophrenia were more likely to have other gaps or duplicated sections elsewhere in their genetic code that could disrupt the action of other genes.

The third international team, which included Queensland researchers, identified three single letter mutations linked to increased risk. The researchers cautioned it would be premature to develop genetic tests for a predisposition to schizophrenia based on the findings because they did not account for all cases of the disease.


No comments: