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AUTISM: Bad air, genetics add up to higher risk

Posted on Dec 7, 2013

AUTISM: Bad air, genetics add up to higher risk

Air pollution and a common genetic makeup may interact to significantly increase a baby’s risk for autism, USC scientists found. The researchers at USC’s Keck School of Medicine cautioned in an interview that they need to do more studies to replicate their findings. The study, to be published in the January 2014 edition of the journal Epidemiology, found that children with the specific gene who spent their in-utero months and their first year after birth in polluted areas of California had three-fold higher risks for autism disorders. “We need to do more studies, but the genetic disposition and air pollution appear to work together to increase the risk of autism more than the risk of each one alone,” said the study’s lead author, Heather E. Volk, an assistant professor of research in preventive medicine at the medical school. Volk’s earlier work found that children had twice the risk of developing autism if their mothers lived within 1,000 feet of a busy freeway during pregnancy. For this research, Volk collaborated with genetics expert Daniel B. Campbell, an assistant professor in psychiatry and behavioral science at the USC medical school. Campbell explained by telephone that roughly half the population has what geneticists call the “MET receptor tyrosine kinase gene.” The gene is found in about 60 percent of people who have autism, indicating that those with the gene have a higher risk, he said. THE CHILDREN To probe the potential interplay between the gene and air quality, Volk, Campbell and their colleagues analyzed the genetics and air pollution exposures of 408 children in the Sacramento, San Francisco and Los Angeles areas; the children’s cases already were being tracked for research purposes. Of those children, 252 met the diagnostic criteria for the spectrum of autism disorders. Using regional air quality readings and traffic proximity data, the research team determined each child’s air pollution exposure while they were fetuses and in their first year after birth — a critical period in the development of the brain and other organs. The scientists used a blood test to determine each child’s genetics. The team found no increase in the autism risk among the children who had the gene but breathed relatively clean air. But those who had the gene and were exposed to air pollution were three times more likely to have the disease, Volk said. Beth Burt, president of the Autism Society Inland Empire, said she appreciates the research. “It is fascinating and important work,” said Burt, a Corona resident who has an autistic son who is 20. “It is not an either/or situation — genetics or the environment,” she said. “But it may be the combination of a genetic predisposition with an environmental trigger.” Lillian Vasquez, who also has a 20-year-old son with autism, said she was not surprised by USC’s findings. She said she has always thought autism was the result of genetics and some sort of trigger, such as a vaccination or an artificial sweetener. “Air pollution as a trigger seems quite plausible,” she said. Vasquez, vice president of the Inland autism society, has lived in Colton since before her pregnancy. Colton, like most of the Inland area, has long had unhealthful levels of air pollution. OTHER RESEARCH Autism disorders are incurable, lifelong brain disabilities characterized by problems with social interaction, communication and repetitive behaviors. The Centers for Disease Control and Prevention estimates that one in 88 children in the United States has an autism disorder. Thousands of studies have linked air pollution to lung, heart and circulatory disorders. The work by Volk and her colleagues, however, is part of a...

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Toxin-Emitting Bacteria May Be Environmental Trigger for MS

Posted on Nov 15, 2013

Toxin-Emitting Bacteria May Be Environmental Trigger for MS

Could eating meat from animals infected with one type of Clostridia bacteria be the MS ‘smoking gun?’ Researchers may have unearthed a trigger for multiple sclerosis (MS) that’s been hiding in plain sight. Scientists from Weill Cornell Medical College and Rockefeller University have identified a bacterium they believe can trigger MS—and it’s found just about everywhere, including dirt. Their study, published in PLOS ONE, is the first to identify the bacterium, Clostridium (C.) perfringens type B, in humans. They first identified it in the blood of a 21-year-old woman with MS who was having a relapse. She was part of the Harboring the Initial Trigger for MS (HITMS) observational study launched by Timothy Vartanian, a professor of neurology and neuroscience at Weill Cornell Medical College and director of the Judith Jaffe Multiple Sclerosis Center at New York-Presbyterian Hospital and Weill Cornell, and Kareem Rashid Rumah, an MD/PhD student at Weill Cornell and lead investigator. See 13 Early Signs of MS » Getting the Dirt on C. perfringens C. perfringens, found in soil, is one of the most common types of bacteria in the world. It has five subsets, A through D. Type A commonly occurs in the human gastrointestinal tract and is thought to be harmless. Types B and D, however, can emit a harmful substance called epsilon toxin when eaten by grazing livestock. The substance travels through the bloodstream, crossing the blood-brain barrier and destroying myelin, causing MS-like symptoms in the animals. Vartanian, Rashid, and their team wondered if C. perfringens types B or D could be identified in humans. They tested the blood of both MS patients and healthy control subjects. In samples from MS patients, the levels of antibodies to the toxins were 10 times higher than in the healthy controls. They also noted that only one sample in 100 from the healthy controls showed any sign of exposure to the bacteria. Researchers hypothesize that eating grazing animals who are infected with the bacteria could be the way C. perfringens Type B is introduced into the human digestive system. The human gut plays host to many types of bacteria, not all of them bad. Some are actually necessary for maintaining good health. Researchers suppose that the reason one person reacts to the toxin emitted by the bacteria while another does not may depend on the natural balance of bacteria in a person’s gut. Learn 6 Surprising Facts About the Microbes Living in Your Gut » “We believe the toxin enters the blood from the gut,” said Vartanian in an interview with Healthline. “Once in the blood, the toxin binds to a specific receptor present on the [lining of] the brain blood vessels, resulting in injury to the blood brain barrier (BBB). The toxin in the blood can then enter the brain at focal sites of BBB injury and bind to the same receptor on oligodendrocytes, the myelin forming cells of the central nervous system, resulting in oligodendrocyte death.” Bacterial “Relapses” The type B bacteria, once settled in the gut, goes through growth cycles followed by periods of dormancy. Since the toxin is only emitted during active periods, it is not always present in the bloodstream. Researchers are intrigued by this cyclical activity and hope to investigate whether these growth cycles coincide with relapses in people with relapsing-remitting forms of MS. “We are working on that now and need funding to push this project faster,” said Vartanian. The findings of this small study are exciting, but must be replicated by other researchers. Could the immune response seen in MS patients in fact be caused by the body’s attempt to fight the toxin? According to the researchers, it’s possible....

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Lizards Slow Lyme Disease in Western U.S.

Posted on Nov 11, 2013

Lizards Slow Lyme Disease in Western U.S.

It may sound like witchcraft, but Berkeley scientists have found that ticks who feast on the blood of the common western fence lizard are purged of any Lyme disease bacteria hiding in their gut. The newly published findings may explain why there is less tick-borne Lyme disease in California than in the eastern United States, where the debilitating illness was first discovered and given its name. Researchers suspect that a yet- to-be-identified protein in the lizard’s blood destroys the microbes that would otherwise flourish in the tick’s belly and can be later transmitted to human victims. “We’ve speculated on this for years, and now we have fairly good evidence that this is the case,” said Robert Lane, a University of California at Berkeley insect biologist who has been studying ticks and Lyme disease for more than a decade. Lane and his colleague Gary Quistad conducted a series of laboratory experiments using young Lyme disease-infected ticks and fence lizards. In the nymphal stage during which they feed on the blood of lizards, the ticks are only about the size of a poppy seed. But it is common to find 30 to 40 at one time sharing the blood of a single fence lizard. Although infected adult female ticks pose a serious threat of transmitting Lyme disease to humans, the smaller nymphal ticks are the most dangerous because they are harder to find and are still capable of transmitting the disease. Lane had determined eight years ago that the lizards appeared to be immune to Lyme disease despite infestation with tick nymphs. His latest research, published recently in the Journal of Parasitology, suggest why this happens. The experiments first ruled out the possibility that antibodies produced by the lizard’s immune system were able to neutralize the Lyme disease bacteria. Test tube experiments found that Lyme disease bacteria bathed in lizard’s blood died within one hour, while control samples grown in mouse blood lasted three days. In another experiment, the researchers heated lizard blood to the boiling point, and found that it no longer killed the bacteria in a test tube. The sum of these tests points to what Lane calls a “spirochete-killing factor” that is probably a large protein. “It’s an extremely important paper,” said Vicky Kramer, chief of the vector-borne disease section of the California Department of Health Services. Researchers are now trying to determine the precise nature of the Lyme disease-killing protein, and perhaps find out if it can be used to create a treatment for the disease. Lane said he has not yet discussed his findings with biotechnology companies. California health officials long have been pleasantly puzzled by the fact that Lyme disease is a relative rarity in the state, despite an abundance of ticks. Lane points out that in the eastern regions with higher Lyme disease rates, “they don’t have fence lizards there.” Berkeley’s Tilden Park served as the field laboratory for Lane, where he previously also uncovered a curious quirk about Lyme disease and the black-legged ticks that carry it there: the infection rates for young ticks, while low, was three to four times higher than the rate in adult ticks. The latest findings again suggest why: When young nymphal ticks feed on the fence lizards, the mysterious protein not only protects the lizard from infection — it actually leaches into the tick’s gut and kills the bacteria there. READ...

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Research finds brain scans may aid in diagnosis of autism

Posted on Nov 6, 2013

Research finds brain scans may aid in diagnosis of autism

Joint research from the University of Alabama at Birmingham Department of Psychology and Auburn University indicates that brain scans show signs of autism that could eventually support behavior-based diagnosis of autism and effective early intervention therapies. The findings appear online today in Frontiers in Human Neuroscience as part of a special issue on brain connectivity in autism. “This research suggests brain connectivity as a neural signature of autism and may eventually support clinical testing for autism,” said Rajesh Kana, Ph.D., associate professor of psychology and the project’s senior researcher. “We found the information transfer between brain areas, causal influence of one brain area on another, to be weaker in autism.” The investigators found that brain connectivity data from 19 paths in brain scans predicted whether the participants had autism, with an accuracy rate of 95.9 percent. Kana, working with a team including Gopikrishna Deshpande, Ph.D., from Auburn University’s MRI Research Center, studied 15 high-functioning adolescents and adults with autism, as well as 15 typically developing control participants ages 16-34 years. Kana’s team collected all data in his autism lab at UAB that was then analyzed using a novel connectivity method at Auburn. The current study showed that adults with autism spectrum disorders processed social cues differently than typical controls. It also revealed the disrupted brain connectivity that explains their difficulty in understanding social processes. “We can see that there are consistently weaker brain regions due to the disrupted brain connectivity,” Kana said. “There’s a very clear difference.” Participants in this study were asked to choose the most logical of three possible endings as they watched a series of comic strip vignettes while a functional MRI scanner measured brain activity. The scenes included a glass about to fall off a table and a man enjoying the music of a street violinist and giving him a cash tip. Most participants in the autism group had difficulty in finding a logical end to the violinist scenario, which required an understanding of emotional and mental states. The current study showed that adults with autism spectrum disorders struggle to process subtle social cues, and altered brain connectivity may underlie their difficulty in understanding social processes. “We can see that the weaker connectivity hinders the cross-talk among brain regions in autism,” Kana said. Kana plans to continue his research on autism. “Over the next five to 10 years, our research is going in the direction of finding objective ways to supplement the diagnosis of autism with medical testing and testing the effectiveness of intervention in improving brain connectivity,” Kana said. Autism is currently diagnosed through interviews and behavioral observation. Although autism can be diagnosed by 18 months, in reality, earliest diagnoses occur around ages 4-6 as children face challenges in school or social settings. “Parents usually have a longer road before getting a firm diagnosis for their child now,” Kana said. “You lose a lot of intervention time, which is so critical. Brain imaging may not be able to replace the current diagnostic measures; but if it can supplement them at an earlier age, that’s going to be really helpful.” The findings of this study build on Kana’s research collaborations with Auburn that began in 2010. Lauren Libero, a graduate student in the UAB Department of Psychology, assisted in the research. READ...

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Study Points to Methylation-based ‘Clock’ for Determining Tissue Age

Posted on Oct 21, 2013

Study Points to Methylation-based ‘Clock’ for Determining Tissue Age

NEW YORK (GenomeWeb News) – Methylation marks across the human genome may make up an “epigenetic clock” for gauging the chronological age of various tissues in the human body, according to a study published online last night in Genome Biology. A University of California at Los Angeles researcher used a computational method to fish out more than 350 age-informative cytosine methylation markers from thousands of healthy samples collected across the human lifespan and profiled using microarrays for prior studies. Findings from the study suggest the resulting methylation-based aging predictor can accurately determine chronological age across multiple tissue types. The work also offered insights into how tissues age with time and revealed differences in aging profiles between tissues and in tumor samples. More work is needed to untangle the nature of the relationship between age and the methylation profiles described in the study. “The big question is whether the biological clock controls a process that leads to aging,” the study’s author, Steve Horvath, a human genetics and biostatistics researcher affiliated with UCLA’s David Geffen School of Medicine and the UCLA Fielding School of Public Health, said in a statement. “If so, the clock will become an important biomarker for studying new therapeutic approaches to keeping us young,” he added. In an effort to explore previously proposed ties between aging and epigenetics, Horvath brought together cytosine methylation profiles that had been ascertained for 7,844 samples using Illumina 27K or 450K arrays. The sample represented 51 non-cancerous human tissue and/or cell types and came from 82 different datasets, Horvath noted. With a training set that included 39 of the datasets, he used a so-called elastic net regression model to whittle down to a set of 352 cytosine methylation marks that appeared promising for predicting the age of multiple tissues. This methylation-based epigenetic clock was subsequently validated in healthy samples from dozens more studies before being used to assess aging patterns at specific cell stages or in tissue types. After establishing these methylation-based clocks in normal tissues, for instance, Horvath turned his attention to 5,826 cancer samples from 32 different DNA methylation datasets. That arm of the analysis indicated that the ability to predict age using the methylation clock tends to break down somewhat in tumor samples. Generally speaking, though, cancers have DNA methylation “ages” beyond their years and appear far older than corresponding non-cancerous tissue. That was especially true for tumors containing relatively modest somatic mutation burdens. It was also the case for some of the breast cancer samples examined in the study, though even normal breast tissue appeared to acquire more aged methylation marks than other tissues of the same chronological age. “Healthy breast tissue is about two to three years older than the rest of a woman’s body,” Horvath noted. “If a woman has breast cancer, the healthy tissue next to the tumor is an average of 12 years older than the rest of her body.” Breast tissue was one of the tissue types that showed less precise calibration on the DNA methylation-based aging clock, Horvath noted, particularly in the cancerous cases. But for samples from women without cancer, the epigenetic clock came up with age estimates that were within around seven-and-a-half years of individuals’ chronological age, on average. Induced pluripotent stem cells had “young” or “reset” epigenetic clocks, according to the study, reverting to methylation patterns reminiscent of those found in embryonic stem cells. At the other extreme, Horvath saw that methylation marks did not seem to coincide with age in samples from individuals with premature-aging conditions such as Werner syndrome or Hutchinson-Gilford progeria. Based on findings so far,...

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