Wednesday, October 01, 2014

Study sheds light on asthma and respiratory viruses

Researchers try to find out why people with asthma have
more difficulty when contracting a respiratory virus.
People with asthma often have a hard time dealing with respiratory viruses such as the flu or the common cold, and researchers have struggled to explain why.

In a new study that compared people with and without asthma, the answer is becoming clearer. The researchers found no difference in the key immune response to viruses in the lungs and breathing passages.

The work, at Washington University School of Medicine in St. Louis, suggests that a fundamental antiviral defense mechanism is intact in asthma.

This means that another aspect of the immune system must explain the difficulty people with asthma have when they encounter respiratory viruses.

Among researchers who study asthma, there is debate over why patients with this common breathing disorder might have more trouble dealing with airway viruses than people without asthma.

The debate has centered on the role of proteins called interferons, which are released by cells lining the airways and are so named because they "interfere" with an invading virus.

"One school of thought says there is a defect in interferon production — that patients with asthma don't produce enough interferon," said senior author Michael J. Holtzman, MD, the Selma and Herman Seldin Professor of Medicine. "But we couldn't find any significant differences between the two groups. In fact, we were struck by how similar they were."

Holtzman and his colleagues looked at two common airway viruses — influenza A and respiratory syncytial virus (RSV) — and the interferon response they triggered in airway cells sampled from 11 patients with mild to severe asthma and seven control participants without asthma.

Though the study's sample size was small, the researchers performed an elaborate analysis that took into consideration the downstream events triggered by interferon release.

"Even though we showed both groups made similar amounts of interferon, we recognized that there might be a difference in effectiveness, a difference in how well it triggered downstream events necessary to fighting the virus," Holtzman said.

To find out whether the same amount of interferon might be less effective in patients with asthma, the investigators compared the genes activated by interferon in both groups of patients.

"The products of these genes are very effective in their antiviral action," Holtzman said. "But on the other side, the virus has a lot of ways of getting around them. So it's a battlefield. Who will win out? The interferon-stimulated genes or the viral genes?"

Holtzman and his colleagues showed that even in this downstream activation of genes, asthma patients and those without the condition were remarkably similar.

They also measured similar amounts of virus living in the cells at various points of time during the study, indicating that the battles against the viruses progressed similarly in both groups.

"Whatever is causing asthmatics and non-asthmatics to experience differences in how well they recover from these respiratory infections — why patients with asthma are more likely to end up in the hospital, for example — this interferon mechanism is not the deciding factor based on what we've seen so far," Holtzman said.

Given the complexity of the immune system, there are many other possible culprits to investigate. Holtzman and his colleagues are continuing to research these possibilities in similar studies with larger sample sizes and in studies looking at different aspects of the immune system.

One likely possibility that the group has proposed is that viruses have a special means to induce inflammatory airway disease, and the susceptibility to this process may be an essential feature of asthma and related lung diseases such as chronic obstructive pulmonary disease.

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Wednesday, September 10, 2014

Greenest neighbourhoods produce bigger babies

Expecting mothers with access to trees and
grass delivered heavier babies: Study
Mothers who live in Metro Vancouver’s greenest neighbourhoods tend to deliver bigger babies and are more likely carry a baby to term than those who live in less green parts of the city, according to a new study published in the journal Environmental Health Perspectives.

Using data from more than 64,000 births and analysis of satellite imagery, researchers found that babies from the greenest residential spaces ­­— those with access to trees and grass within 100 metres — were up to 45 grams heavier, had a reduced likelihood of preterm birth and were less likely to be small for gestational age, according to the lead researcher Michael Brauer, a professor in the School of Population and Public Health at the University of British Columbia.

The positive effects of greenness persist even when the researchers control for other factors known to influence gestation and birth weight, including air pollution, noise, income, access to parks, opportunities for physical activity and the walkability of the immediate neighbourhood.

“We know from other studies that birth outcomes are influenced by pollution and noise in a negative way, so we went looking for something (in the urban environment) that is healthy,” said Brauer.

Cities in most of the developed world are designed to accommodate the automobile, which usually results in relatively barren, noisy and polluted environments. Brauer’s study seeks to quantify the benefits of a different approach to urban planning.

“If we didn’t design for automobiles and instead designed for people, the hope is that we would be healthier,” he said. “With the high cost of health care, modifying urban design features such as increasing green space may turn out to be an extremely cost-effective strategy to prevent disease.”

While 45 grams isn’t a lot of extra weight for one healthy infant, the effect of increased birth weight across the entire distribution of births moves thousands of babies from birth weights that are dangerously low into a healthier range.

“From a medical standpoint, those are small changes in birth weight, but across a large population, those are substantial differences that would have a significant impact on the health of infants in a community,” said co-author Perry Hystad, assistant professor in the College of Public Health and Human Sciences at Oregon State University.

Even in an urban area as rich in green space as Metro Vancouver the benefits conferred by the very greenest neighbourhoods compared with the least green neighbourhoods were substantial, including a 20-per-cent reduction in severely premature births and 13 per cent fewer moderately pre-term births.

The mechanism by which greenness translates into healthier babies is not exactly clear, but greener environments are known to facilitate social connectedness and reduce blood pressure, heart rate and stress-related hormones, according to the study, the third in a series of similar inquiries on the health impacts of urban spaces.

“Even when we eliminate the noise and the pollution and (a measure) of physical activity, we still see this benefit of green space,” he said. “What we don’t know is whether it is enough to see a tree out your window or do you have to have a park across the street where you chat with your neighbours.”

Source: Vancouver Sun

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Friday, August 08, 2014

Air pollution actually beat first explorers to the South Pole

Roald Amundsen/ public domain
Norwegian explorer Roald Amundsen became the first man to reach the South Pole in December 1911, but scientists say industrial air pollution beat him to it.

"Our new record shows the dramatic impact of industrial activities such as smelting, mining and fossil fuel burning on even the most remote parts of the world," said Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada.

Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by McConnell, created the most accurate and precise reconstruction to date of lead pollution over Earth’s southernmost continent.

"It is very clear that industrial lead contamination was pervasive throughout Antarctica by the late 19th century, more than two decades before the first explorers made it to the South Pole," he added. "The idea that Amundsen and Scott were traveling over snow that clearly was contaminated by lead from smelting and mining in Australia, and that lead pollution at that time was nearly as high as any time ever since, is surprising to say the least."
This study included ice cores collected as part of projects funded by the National Science Foundation. Additional ice cores were contributed to the study by international collaborators including the British Antarctic Survey, the Australian Antarctic Division and the Alfred Wegener Institute in Germany.

"The ice cores obtained through international collaborations were critical to the success of this study in that they allowed us to develop records from parts of Antarctica not often visited by U.S.-based scientists," said co-author Tom Neumann of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who participated in a Norway-U.S. traverse that collected several of the cores used in this study. "This included the Law Dome region of East Antarctica and a big section of East Antarctica visited by the Norwegian-United States Scientific Traverse of East Antarctica."

"Lead is a toxic heavy metal with strong potential to harm ecosystems," said co-author Paul Vallelonga of the University of Copenhagen. "While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby Port Pirie."

Data from the new ice core array illustrates that Antarctic lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the Great Depression and the end of World War II. Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.
 "Our measurements indicate that approximately 660 tonnes [1.5 million pounds] of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years," McConnell said. "While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."

The report is published in the online edition of the Nature Publishing Group’s journal Scientific Reports.

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Tuesday, August 05, 2014

Common chemical in mothers may negatively affect the IQ of their unborn children

In some women abnormally high levels of a common and pervasive chemical may lead to adverse effects in their offspring. The study, published recently in the Journal of Clinical Endocrinology and Metabolism, is the first of its kind to shed light on the possible harmful side effects of perchlorate in mothers and their children.

"The reason people really care about perchlorate is because it is ubiquitous. It's everywhere," said Elizabeth Pearce, MD, MSc, associate professor of medicine at the Boston University School of Medicine (BUSM). "Prior studies have already shown perchlorate, at low levels, can be found in each and every one of us."

Using data from the Controlled Antenatal Thyroid Study (CATS), researchers at Boston University School of Medicine (BUSM) and Cardiff University studied the effect of perchlorate, an environmental contaminant found in many foods and in some drinking water supplies, and its effects on children born to mothers with above average levels of this substance in their system. They studied 487 mother-child pairs from women with underactive thyroid glands and in the 50 women with the highest levels of perchlorate in their body, their offspring had below average IQ levels when compared to other children.

Perchlorate is a compound known to affect the thyroid gland, an organ needed to help regulate hormone levels in humans. According to Pearce, previous studies have attempted to implicate this anti-thyroid activity in pregnant mothers as a possible cause of hypothyroidism, or an underactive thyroid gland. Hypothyroidism in newborns and children can lead to an array of unwelcome side effects, including below average intelligence.



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Monday, August 04, 2014

Air pollution and climate change will curb world food supplies

Howden/freedigitalphotos

Researchers at MIT say that the double-whammy of air pollution and rising world temperatures could affect our most important food sources.

The study looked in detail at global production of four leading food crops — rice, wheat, corn, and soy — that account for more than half the calories humans consume worldwide. It predicts that effects will vary considerably from region to region, and that some of the crops are much more strongly affected by one or the other of the factors: For example, wheat is very sensitive to ozone exposure from air pollution, while corn is much more adversely affected by heat.

The research was carried out by Colette Heald, an associate professor of civil and environmental engineering (CEE) at MIT, former CEE postdoc Amos Tai, and Maria van Martin at Colorado State University. Their work is described this week in the journal Nature Climate Change.

Heald explains that while it's known that both higher temperatures and ozone pollution can damage plants and reduce crop yields, "nobody has looked at these together." And while rising temperatures are widely discussed, the impact of air quality on crops is less recognized.

In the United States, tougher air-quality regulations are expected to lead to a sharp decline in ozone pollution, mitigating its impact on crops. But in other regions, the outcome "will depend on domestic air-pollution policies," Heald says. "An air-quality cleanup would improve crop yields."

Overall, with all other factors being equal, warming may reduce crop yields globally by about 10 percent by 2050, the study found. But the effects of ozone pollution are more complex — some crops are more strongly affected by it than others — which suggests that pollution-control measures could play a major role in determining outcomes.

Ozone pollution can also be tricky to identify, Heald says, because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.

Potential reductions in crop yields are worrisome: The world is expected to need about 50 percent more food by 2050, the authors say, due to population growth and changing dietary trends in the developing world.

While heat and ozone can each damage plants independently, the factors also interact. For example, warmer temperatures significantly increase production of ozone from the reactions, in sunlight, of volatile organic compounds and nitrogen oxides. Because of these interactions, the team found that 46 percent of damage to soybean crops that had previously been attributed to heat is actually caused by increased ozone.

Under some scenarios, the researchers found that pollution-control measures could make a major dent in the expected crop reductions following climate change. For example, while global food production was projected to fall by 15 percent under one scenario, larger emissions decreases projected in an alternate scenario reduce that drop to 9 percent.

Air pollution is even more decisive in shaping undernourishment in the developing world, the researchers found: Under the more pessimistic air-quality scenario, rates of malnourishment might increase from 18 to 27 percent by 2050 — about a 50 percent jump; under the more optimistic scenario, the rate would still increase, but that increase would almost be cut in half, they found.

Agricultural production is "very sensitive to ozone pollution," Heald says, adding that these findings "show how important it is to think about the agricultural implications of air-quality regulations. Ozone is something that we understand the causes of, and the steps that need to be taken to improve air quality."


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