Showing posts with label research. Show all posts
Showing posts with label research. Show all posts

Tuesday, April 07, 2015

Air pollution slows brain development: study

Air pollution takes a double toll on babies' brains

Studies have tied air pollution to a wide range
of problems in children.
A common pollutant in vehicle exhaust, power plant emissions and cigarette smoke can shrink white matter in fetal brains and cause developmental damage during the toddler years, a new study suggests.

In 40 children examined by researchers, prenatal exposure to polycyclic aromatic hydrocarbons was correlated with reduced white matter on the left side of children's brains during their early childhood.

Those physical changes in the brain's internal wiring also were correlated with slower cognitive processing and with symptoms of attention deficit and hyperactivity, according to the study published in the journal JAMA Psychiatry.

“They tend to be fidgety and hyperactive and very impulsive, so they leap before they look,” said Dr. Bradley Peterson, director of the Institute for the Developing Mind at Children's Hospital Los Angeles and the lead author of the report.

The researchers had previously tied behavioral and cognitive problems to eight common types of these pollutants, which are a product of incomplete combustion of organic materials.

The new study now suggests those problems have a biological root in the altered architecture of the brain.

The research involved 655 New York City women of Dominican and African American descent who gave birth between 1997 and 2006.

During late pregnancy, the women carried detector backpacks that measured exposure to PAHs over 48 hours. Their children later were tested for exposure and underwent several rounds of cognitive and behavioral testing.

For the JAMA Psychiatry study, Peterson and his colleagues selected a representative sample from the original study group: 20 children whose own PAH readings were below the median and 20 whose PAH levels were above it.

All the children were about 8 years old when they underwent magnetic resonance imagery scans.

Those scans showed that white matter was significantly reduced from normal volumes throughout the left hemisphere, an area that controls language and cognition, among other higher functions.

In fact, the higher their prenatal exposure to PAH was, the more white matter was reduced and the more acute the behavioral and developmental problems were, the study found.

Scientists don’t know why the left side seemed to be affected more, but they suspect the compounds interfere with an early biochemical process that helps the fetal brain divide into slightly asymmetrical hemispheres.

The damage, however, is not isolated to prenatal stages, or to the left hemisphere. Postnatal PAH exposure, measured at age 5, correlated with diminished white matter in areas of the prefrontal cortex of both hemispheres, the study found.

“It’s a double hit,” Peterson said. “They have the abnormality from prenatal life throughout the left hemisphere and then on top of that they have this bilateral frontal hit from exposures around age 5.”

The 40 children were from nonsmoking homes and had little or no exposure to lead or insecticides that likewise have been linked to developmental and behavioral problems, according to the study. All were right-handed.

Although it remains possible that other pollutants could be affecting the results, the researchers said their sampling methods eliminated the major contenders, helping to isolate the effects of the PAH compounds.

Numerous studies have linked air pollution — especially particulate matter — to respiratory and cardiac problems. But over the last decade, researchers have accumulated more evidence that particles and other types of airborne pollution can affect brain development.

A 2012 study using a database of 19,000 nurses found greater cognitive decline among older women exposed to high levels of particulate matter.

A 2011 Boston study involving 680 men showed similar results. A series of studies involving children in Mexico City linked air pollution with the brain inflammation that is typical of diseases such as multiple sclerosis.

“It is worrisome,” Peterson said of the latest findings. “California has gone a long way toward improving and cleaning up the air, but there’s a long way to go. Future generations depend on it.”

Source: LA Times

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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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Thursday, July 31, 2014

Asthma drugs suppress children's growth say researchers

Corticosteroid drugs that are given by inhalers to children with asthma may suppress their growth, evidence suggests.

Two new systematic reviews published in The Cochrane Library focus on the effects of inhaled corticosteroid drugs (ICS) on growth rates.

The authors found children’s growth slowed in the first year of treatment, although the effects were minimized by using lower doses.

Inhaled corticosteroids are prescribed as first-line treatments for adults and children with persistent asthma.

They are the most effective drugs for controlling asthma and clearly reduce asthma deaths, hospital visits and the number and severity of exacerbations, and improve quality of life.

Yet, their potential effect on the growth of children is a source of worry for parents and doctors.

Worldwide, seven ICS drugs are currently available: beclomethasone, budesonide, ciclesonide, flunisolide, fluticasone, mometasone and triamcinolone.

Ciclesonide, fluticasone and mometasone are newer and supposedly safer drugs.

The first systematic review focused on 25 trials involving 8,471 children up to 18 years old with mild to moderate persistent asthma.

These trials tested all available inhaled corticosteroids except triamcinolone and showed that, as a group, they suppressed growth rates when compared to placebos or non-steroidal drugs. 14 of the trials, involving 5,717 children, reported growth over a year.

The average growth rate, which was around 6-9 cm per year in control groups, was reduced by about 0.5 cm in treatment groups.

The researchers found that growth suppression varied across studies, and so they looked at the relationship between a variety of factors and their effects on growth. Some of the variation could be explained by the drugs used, although since this was an indirect comparison the authors say more evidence is needed.

“Conclusions about the superiority of one drug over another should be confirmed by further trials that directly compare the drugs,” said Zhang.

More long-term trials and trials comparing different doses are also needed, particularly in children with more severe asthma requiring higher doses of inhaled corticosteroids, the researchers conclude.

“Only 14% of the trials we looked at monitored growth in a systematic way for over a year. This is a matter of major concern given the importance of this topic,” said Francine Ducharme, one of the authors of both reviews and senior author of the second review, based at the Department of Paediatrics at the University of Montreal in Montreal, Canada.

“We recommend that the minimal effective dose be used in children with asthma until further data on doses becomes available. Growth should be carefully documented in all children treated with inhaled corticosteroids, as well in all future trials testing inhaled corticosteroids in children.”

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Wednesday, April 09, 2014

Coughs and sneezes staying airborne

Cold and flu pathogens may stay airborne for long
distances after a sneeze or a cough, researchers say.
The next time you feel a sneeze coming on, raise your elbow to cover up that multiphase turbulent buoyant cloud you're about to expel.

That's right: A novel study by MIT researchers shows that coughs and sneezes have associated gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously realized.

"When you cough or sneeze, you see the droplets, or feel them if someone sneezes on you," says John Bush, a professor of applied mathematics at MIT, and co-author of a new paper on the subject.

"But you don't see the cloud, the invisible gas phase. The influence of this gas cloud is to extend the range of the individual droplets, particularly the small ones."

Indeed, the study finds, the smaller droplets that emerge in a cough or sneeze may travel five to 200 times further than they would if those droplets simply moved as groups of unconnected particles � which is what previous estimates had assumed.

The tendency of these droplets to stay airborne, resuspended by gas clouds, means that ventilation systems may be more prone to transmitting potentially infectious particles than had been suspected.

With this in mind, architects and engineers may want to re-examine the design of workplaces and hospitals, or air circulation on airplanes, to reduce the chances of airborne pathogens being transmitted among people.

"You can have ventilation contamination in a much more direct way than we would have expected originally," says Lydia Bourouiba, an assistant professor in MIT's Department of Civil and Environmental Engineering, and another co-author of the study.

The paper, "Violent expiratory events: on coughing and sneezing," was published in the Journal of Fluid Mechanics.

It is co-written by Bourouiba, Bush, and Eline Dehandschoewercker, a graduate student at ESPCI ParisTech, a French technical university, who previously was a visiting summer student at MIT, supported by the MIT-France program.

Smaller drops, longer distances

The researchers used high-speed imaging of coughs and sneezes, as well as laboratory simulations and mathematical modeling, to produce a new analysis of coughs and sneezes from a fluid-mechanics perspective.

Their conclusions upend some prior thinking on the subject. For instance: Researchers had previously assumed that larger mucus droplets fly farther than smaller ones, because they have more momentum, classically defined as mass times velocity.

That would be true if the trajectory of each droplet were unconnected to those around it. But close observations show this is not the case; the interactions of the droplets with the gas cloud make all the difference in their trajectories. Indeed, the cough or sneeze resembles, say, a puff emerging from a smokestack.

A cough or sneeze is a "multiphase turbulent buoyant cloud," as the researchers term it in the paper, because the cloud mixes with surrounding air before its payload of liquid droplets falls out, evaporates into solid residues, or both.

"The cloud entrains ambient air into it and continues to grow and mix," Bourouiba says. "But as the cloud grows, it slows down, and so is less able to suspend the droplets within it. You thus cannot model this as isolated droplets moving ballistically."

The MIT researchers are now developing additional tools and studies to extend our knowledge of the subject. For instance, given air conditions in any setting, researchers can better estimate the reach of a given expelled pathogen.

Source: EurekAlert

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Thursday, October 13, 2011

The science of dust particles

Indoor dust is made up of organic matter like
skin particles, allergens, quartz and chemicals.
Dust is something we simply have to live with, no matter how much we clean or what we clean with.

At any given time, dust particles will be present in any given room – even the most sterile scientific cleanrooms.

But not all dust is created equal.

Researchers at Ohio State University have looked at the composition of unique dust particles in their lab and isolated a whopping 63 different dust particles.

What kind of dust are we breathing?

Organic matter was the most common ingredient of indoor dust, including skin particles, dander, pollen and more.

Indoor dust also includes quartz, one of the most abundant minerals on the planet’s surface after feldspar.

Many dust particles also contained synthetic chemicals coming from air pollution, fertilizers (pesticides) and construction materials like drywall.

Small dust particles have long been a public health concern, as they can penetrate deep into the lungs and cause inflammation, aggravate existing health conditions or lead to serious illness down the road.

The researchers’ findings have been published in the recent issue of The Journal of Physical Chemistry C.

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Tuesday, September 27, 2011

Study shows the high costs of colds in North America

The cost of colds and the flu weighs heavily on Canadian
and US workers, a new study shows.
A Canadian study on the impact of colds and flu on school absenteeism, the workplace and the economy found that the costs are staggering.

In the first study of its kind, the researchers reviewed published clinical trials, studies and research projects from more than 300 researchers. 

The report with the title "Why the Common Cold and Flu Matter" pointed out the following highlights.
  • 1/3 of Canadian adults have a sore throat, cold or flu in any given month. More common in women than men.  
  • 2/3 of Canadian adults experiencing the first signs of a cold or flu used some type of self-treatment. Women were more likely to self treat and also consult a doctor as compared to men.  
  • 1/5 of Canadian adults ignore symptoms altogether  
  • Cough/cold remedies are the second most commonly used medications in Canada.  
  • Canadians spend more than $300 million a year on over-the-counter cold and flu treatments and prescription antibiotics which, for the most part, neither "...ameliorate symptoms nor change the course of the illnesses."

The researchers say prevention can make a big difference in reducing the impact of colds and the flu.

While children in schools and daycare easily spread infections and colds, adults are also to blame, the study found, as many continue to go to work when they are sick and the spreading diseases lead to much greater productivity losses and increased costs for companies.

In fact, 83% of participants in a U.S. survey on work and illness say they continued to attend work or school while experiencing symptoms of an influenza-like illness. 

This behavior adds up to a significant economic cost as researchers cite direct costs due to lost productivity from colds at $25 billion in the U.S. 

Taking into consideration both indirect (lost productivity) and direct (doctor visits and medicine) costs, of colds, the figure in the U.S. annually is $40 billion.

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Thursday, July 28, 2011

Too much BPA in our environment? EPA considers new action

The chemical BPA even shows up on
money around the world.

The United States Environmental Protection Agency asked for public input earlier this week to determine whether it needed to take more action with regards to the widespread occurrence of BPA.

The commercial chemical bisphenol A is an ingredient in many plastics and food-contact resins and has become a concern because people are more exposed to it than previously believed.

“A number of concerns have been raised about the potential human health and environmental effects of BPA,” a Science New article quoted Steve Owens, assistant administrator for EPA’s Office of Chemical Safety and Pollution Prevention. 

Data from the proposed new tests, he said, “would help EPA better understand and address the potential environmental impacts of BPA.”

It may require new toxicity testing and environmental sampling because of a concern that it “is a reproductive, developmental, and systemic toxicant in animal studies and is weakly estrogenic, there are questions about its potential impact, particularly on children’s health and the environment,” EPA notes on the BPA Action Plan website.

Recent animal studies have shown that even low level exposure to BPA can have worrying health effects.

Recent findings include:

  • Studies involving mice showed that early exposures — in the womb and up through a period equivalent to puberty — could affect gender-linked behaviors in adults: Males became subtly feminized, and in one instance females appeared somewhat masculinized.
  • One human study linked higher BPA exposures in the womb to subtly altered gender-specific behavior in toddlers: Girls became somewhat more aggressive than normal; boys more anxious and withdrawn.
  •  Low-dose exposures in one study, where mice had been exposed to BPA during fetal development, resulted in later prediabetes when the rodents reached early middle age.
  • A 2009 study in mice showed that the uterus of female mice exposed in the womb to BPA became supersensitized to the effects of estrogen in adulthood; a change that the authors said might jeopardize reproduction. (A test-tube study reported by others at the same time — at the Endocrine Society meeting — showed BPA altered the contractile rate of heart-muscle cells, especially in the presence of estrogen).
  • Genetic studies using roundworms showed it affected the genes responsible for successful reproduction and could cause sterility.


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