Breathing in diesel exhaust leads to changes 'deep under the hood'

A student participates in the study while seated in a booth.
Credit: Image courtesy of University of British Columbia

Just two hours of exposure to diesel exhaust fumes can lead to fundamental health-related changes in biology by switching some genes on, while switching others off, according to researchers at the University of British Columbia and Vancouver Coastal Health.

The study involved putting volunteers in a polycarbonate-enclosed booth -- about the size of a standard bathroom -- while breathing in diluted and aged exhaust fumes that are about equal to the air quality along a Beijing highway, or a busy port in British Columbia.

The researchers examined how such exposure affected the chemical "coating" that attaches to many parts of a person's DNA. That carbon-hydrogen coating, called methylation, can silence or dampen a gene, preventing it from producing a protein -- sometimes to a person's benefit, sometimes not. Methylation is one of several mechanisms for controlling gene expression, which is the focus of a rapidly growing field of study called epigenetics.

The study, published this month in Particle and Fibre Toxicology, found that diesel exhaust caused changes in methylation at about 2,800 different points on people's DNA, affecting about 400 genes. In some places it led to more methylation; in more cases, it decreased methylation.

How these changes in gene expression translate to health is the next step for researchers. But this study shows how vulnerable our genetic machinery can be to air pollution, and that changes are taking place even if there are no obvious symptoms.

"Usually when we look at the effects of air pollution, we measure things that are clinically obvious -- air flow, blood pressure, heart rhythm," said senior author Dr. Chris Carlsten, an associate professor in the Division of Respiratory Medicine. "But asthma, higher blood pressure or arrhythmia might just be the gradual accumulation of epigenetic changes. So we've revealed a window into how these long-term problems arise. We're looking at changes 'deep under the hood.'"

The fact that DNA methylation was affected after only two hours of exposure has positive implications, said Carlsten, the AstraZeneca Chair in Occupational and Environmental Lung Disease.

"Any time you can show something happens that quickly, it means you can probably reverse it -- either through a therapy, a change in environment, or even diet," he said.

Carlsten's team, having catalogued the changes along the entire human genome, is now sharing its data with scientists who are further exploring the function of specific genes.

Source: University of British Columbia

A lab in your pocket: Using CAD to load dozens of tests on a lab-on-a-chip

Two computer-generated configurations for routing a droplet through multiple lab-on-a-chip diagnostic tests, many more than are currently possible using manual methods. The software was developed by Michigan Tech's Shiyan Hu and Chen Liao. The figure is reproduced with permission of IEEE Transactions on NanoBioscience. Credit: Chen Liao and Shiyan Hu

When you get sick, your physician may take a sample of your blood, send it to the lab and wait for results. In the near future, however, doctors may be able to run those tests almost instantly on a piece of plastic about the size of credit card.

These labs-on-a-chip would not only be quick -- results are available in minutes -- but also inexpensive and portable. They could be used miles from the nearest medical clinic to test for anything from HIV to diabetes. But as powerful as they may be, they could be far better, says Shiyan Hu, an associate professor of electrical and computer engineering at Michigan Technological University.

Generally, a lab-on-a-chip (LOC) can run no more than a test or two. That's because the chips are designed manually, says Hu. If the LOC were made using computer-aided design, you could run dozens of tests with a single drop of blood.

"In a very short time, you could test for many conditions," he said. "This really would be an entire lab on a chip."

With PhD student Chen Liao, Hu has taken the first step. "We have developed software to design the hardware," he said. Their work focuses on routing the droplet of blood or other fluid through each test on the chip efficiently while avoiding any chip contamination.

"It has taken us four years to do the software, but to manufacture the LOC would be inexpensive," Hu said. "The materials are very cheap, and the results are more accurate than a conventional lab's."

Ultimately, Hu aims to fabricate their own biochip using their software.

Their work was featured on the cover of the March edition of IEEE Transactions on Nanobiosciences and described in the article "Physical-Level Synthesis for Digital Lab-On-a-Chip Considering Variation, Contamination, and Defect." Liao was partially supported by an A. Richard Newton Graduate Scholarship, awarded by the Design Automation Conference.

Source: Michigan Technological University