Biological Psychology Links

By Emily Sohn Chemicals on our produce may contribute to behavior problems in our kids, suggest three new studies. The studies, which looked at a class of pesticides called organophosphates (OP), linked exposure to the chemicals with attention disorders in children, with perhaps the most dramatic impacts to kids who are exposed in the womb and those who are genetically most susceptible. Because pesticide residues linger on fruits and vegetables, the findings suggest that people either buy organic or take the time to wash their produce well. "We don't want women to not eat fruits and vegetables because it's very important to eat them during pregnancy," said Brenda Eskenazi, an epidemiologist and neuropsychologist at the University of California, Berkeley. "I just let water run really thoroughly over fruits, and I rub them so they're clean." Organophosphates are a set of common pesticides that work by attacking the nervous systems of insects. When people are exposed to high levels of the chemicals, they can develop anxiety, confusion impaired concentration, and other serious symptoms. More recently, scientists have started to wonder how chronic exposure at low levels might be affecting people, especially kids, whose nervous systems are still developing. To find out, Eskenazi and colleagues followed up on a long-term study that has tracked more than 300 Mexican-American women in an agriculturally intensive region of California since they first became pregnant in 1999 or 2000. When the women were pregnant, the researchers measured levels of pesticide breakdown products in their urine. More recently, they collected urine samples from the kids and evaluated measures of attention. Â© 2010 Discovery Communications, LLC.

By Marla Cone, Emily Elert and Environmental Health News In a sweltering summer in New York City back in 1999, Yolanda Baldwin was eight months pregnant with her first child. She lived near a gas station and across the street from an intersection choked with exhaust-spewing cars and buses. Sometimes the air was so thick with pollution that she could see it, breathe it, smell it, even taste it. And she often wondered what it might be doing to her unborn child. Now Baldwin and several hundred other mothers whose sons and daughters have been monitored for a decade have an answer: Before children even take their first breath, common air pollutants breathed by their mothers during pregnancy may reduce their intelligence. A pair of studies involving more than 400 women in two cities has found that 5-year-olds exposed in the womb to above-average levels of polycyclic aromatic hydrocarbons, or PAHs, score lower on IQ tests. The compounds, created by the burning of fossil fuels, are ubiquitous in urban environments. In African American and Dominican communities of New York City, 249 children are being monitored for the effects of environmental contaminants until the age of 11. And across the Atlantic, in Krakow, Poland, another 214 children are participating in a parallel study. The findings in Poland, reported this spring, are strikingly similar to New York Cityâ€™s: The children whose mothers had above-average exposure to PAHs scored about four points lower on IQ tests than children whose mothers had below-average exposure. Â© 2010 Scientific American,

LAURA NELSON Jon-Paul Bingham fumbles around for a condom. Big Bertha is waiting. There’s an awkward pause. “It has to be the non-lubricated kind,” he says. Bingham rips open the packet and slips the prophylactic over a small plastic test tube. Big Bertha is one of Bingham’s nine tropical marine cone snails. These colourful creatures are some of the most venomous beasts on the planet. But the powerful poisons they produce can, in tiny doses, help to reveal how nerve cells function — and potentially help to treat conditions from chronic pain to epilepsy. Currently, most neuroscientists obtain their cone snail toxins from dead animals taken from the wild. But Bingham, a biochemist at Clarkson University in upstate New York, believes that the future lies with cone snail farming. Not only might it help conserve wild populations, he says, but it can also yield a wider range of useful toxins. ‘Milking’ the live snails is a hazardous business. One false move and Bingham could be dead in half an hour. Using forceps, he dangles a dead goldfish, the same length as Big Bertha, in front of her. Behind the bait, the condom is stretched over the mouth of the plastic tube. © Nature News Service / Macmillan Magazines Ltd 2004

By HENRY FOUNTAIN To the long list of the unintended effects of environmental contaminants, add one — eating polluted worms affects the songs of male starlings. Researchers from Cardiff University in Wales report in the open-access online journal PLoS One that male starlings that consume estrogen and similar compounds, chemicals normally found in sewage, showed brain and behavioral changes related to singing. Shai Markman, now at the University of Haifa in Israel; Katherine L. Buchanan, now of Deakin University in Australia; and colleagues studied wild starlings foraging at sewage treatment works in southwestern Britain. The birds eat small worms found in huge quantities along filter beds. The worms accumulate natural estrogen excreted in human waste and estrogenlike compounds from plastics manufacturing. The chemicals are known to disrupt endocrine function, with anatomical and behavioral effects. Dr. Buchanan said he was not certain of the effects the chemicals might have on the birds’ songs. With some contaminants toxic to neural development, a result might be less complex songs. “But if you have estrogenic chemicals, that could affect song complexity in the opposite direction,” she said. Copyright 2008 The New York Times Company

Although children in North America are exposed to less lead than children 30 years ago, the lead problem has not disappeared. Lead exposure in inner-city and certain minority populations remains a serious problem. Depending on the intensity of exposure and the age of the exposed person, lead can cause developmental problems, mental retardation, stunted growth, and fertility problems. Add to that a potential new effect of lead exposure: an increased risk of Alzheimer’s Disease. University of Rhode Island neurologist Nasser Zawia and colleagues have published a study in the Journal of Neuroscience, pointing to an association between lead exposure in infancy and Alzheimer’s in adulthood. “People mostly think of lead exposure as being something that only affects children, and nobody has been studying the elderly and adults to see if they’re impacted,” says Zawia. But by studying monkeys exposed to low lead levels in 1980 and 1981, Zawia and his team found evidence that childhood lead exposure could trigger growth of brain plaques associated with Alzheimer’s Disease. “What we found was simply, in the monkeys that were exposed to lead as infants, there was an increase in the expression of the genes involved in Alzheimer’s Disease and the proteins…that are part of the core of the plaques,” Zawia explains. © ScienCentral, 2000-2008.

By CARL ZIMMER The Komodo dragon is already a terrifying beast. Measuring up to 10 feet long, it is the world’s largest lizard. It delivers a devastating bite with its long, serrated teeth, attacking prey as big as water buffaloes. But in a provocative paper to be published this week, an international team of scientists argues that the Komodo dragon is even more impressive. They claim that the lizards use a potent venom to bring down their victims. Other biologists have greeted the notion of giant venomous lizards with mixed reactions. Some think the scientists have made a compelling case, while others say the evidence is thin. Biologists have long been intrigued by the success Komodo dragons have at killing big prey. They use an unusual strategy to hunt, lying in ambush and then suddenly delivering a single deep bite, often to the leg or the belly. Sometimes the victim immediately falls, and the lizards can finish it off. But sometimes a bitten animal escapes. Biologists have noted that the lizard’s victims may collapse later, becoming still and quiet, and even die. For decades, many scientists have speculated that the dragons infected their victims with deadly bacteria that lived in the bits of carrion stuck in their teeth. Yet others have always been skeptical of the bacteria hypothesis. “Your average lion has a much dirtier bite,” said Bryan Fry, a biologist at the University of Melbourne. “It’s complete voodoo.” Copyright 2009 The New York Times Company

By SEAN B. CARROLL Have you ever tried to think up the worst meal you could imagine? How about blue-ringed octopus, floral egg crab, basket shell snails and puffer fish. Sure, some people may think these are delicacies, and puffer fish is certainly treated as such in parts of Asia. But each dish has something more important in common: they are all deadly. Each of these animals is chock full of a powerful neurotoxin called tetrodotoxin. First isolated from the puffer fish, tetrodotoxin is among the most potent toxins known. It is 100 times as toxic by weight as potassium cyanide — two milligrams can kill an adult human — and it is not destroyed by cooking. Just half an ounce of the fish liver, known as fugu kimo in Japan and eaten by daring connoisseurs, can be lethal. When ingested, the toxin paralyzes nerves and muscles, which leads to respiratory failure and, in some cases each year, death. In 1975, the Kabuki actor Bando Mitsugoro VIII ordered four fugu kimo in a restaurant in Kyoto, claiming he could resist the poison. He was wrong. Tetrodotoxin is found in more than just marine creatures. It is present in high concentrations in the skin of certain newts in North America and Japan, and in several kinds of frogs in Central and South America and Bangladesh. The widespread occurrence of tetrodotoxin poses some intriguing riddles. First, how is it that such different animals, belonging to separate branches of the animal kingdom, have all come to possess the same deadly poison? And how is it that they are able to tolerate high levels of tetrodotoxin while others cannot? Copyright 2009 The New York Times Company

Tiny particles enter the brain after being inhaled. JIM GILES Nanoparticles - tiny lumps of matter that could one day to be used to build faster computer circuits and improve drug delivery systems - can travel to the brain after being inhaled, according to researchers from the United States1. The finding sounds a cautionary note for advocates of nanotechnology, but may also lead to a fuller understanding of the health effects of the nanosized particles produced by diesel engines. Günter Oberdörster of the University of Rochester in New York and colleagues tracked the progress of carbon particles that were only 35 nanometres in diameter and had been inhaled by rats. In the olfactory bulb - an area of the brain that deals with smell - nanoparticles were detected a day after inhalation, and levels continued to rise until the experiment ended after seven days. © Nature News Service / Macmillan Magazines Ltd 2004

Meredith Wadman Some parents blame their children’s autism on mercury in vaccines.R. Faris/CorbisThe leading US government funder of autism research is drawing fire over its proposal to run a randomized clinical trial of a treatment widely viewed by experts to be useless and potentially harmful, but that is broadly used for autism. Chelation therapy, in which agents such as dimercaptosuccinic acid (DMSA) are used to bind metal ions in the blood so that they can be excreted easily, is an approved treatment for heavy-metal poisoning. Parents are using such therapy on children with autism because of their belief — which has been scientifically discredited — that mercury from vaccinations caused their children’s condition. In May, investigators at the US National Institute of Mental Health (NIMH) in Bethesda, Maryland, won approval from the US Food and Drug Administration to use DMSA in a trial of children with autism who are aged four to ten years and have detectable, but not toxic, levels of mercury or lead in their blood. The trial, ‘Mercury Chelation to Treat Autism’, is now under ethics review and has not enrolled any patients. Critics say the trial will put children at risk for what is certain to be no medical gain. The American Academy of Pediatrics has concluded that there is no justification for giving children DMSA in the absence of very high levels of heavy-metal exposure, notes epidemiologist Ellen Silbergeld of the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland. “I don’t know why we have to do this experiment again on children.”

HELEN PEARSON
A cell door that automatically snaps shut in milliseconds - this isn't the latest jailbreak deterrent but a fundamental part of our cells. Nearly 50 years after this microscopic marvel was discovered, researchers in New York have dissected the inner workings of the molecule responsible for generating the body's electrical impulses1. All excitable cells - such as those responsible for nerve signals, muscle contraction or the heart beat - depend on ion channels in the cell membrane. Triggered to open by a small voltage, such channels let through a flood of electrically charged ions, then promptly slam shut. The 'ball-and-chain' model was put forward in the 1970s to explain how this 'inactivation' occurs. The model suggested that a plug - or ball - swinging on a molecular 'chain' on the inside of the channel stops up the opening. Now Roderick MacKinnon and his colleagues at Rockefeller University in New York have found that the ball is more like a snake that sneaks inside the channel to block it. 1.Zhou, M., Morais-Cabral, J. H., Mann, S. & MacKinnon, R. Potassium channel receptor site for the inactivation gate and quaternary amine inhibitors. Nature 411, 657–661 (2001). © Macmillan Magazines Ltd 2001 - NATURE NEWS SERVICE Nature © Macmillan Publishers Ltd 2001 Reg. No. 785998 England.

(Philadelphia, PA) – Later this fall, emergency-medicine physicians enter into what they call the "CO season" – a time when faulty furnaces and other mechanical mishaps lead to a spike in cases of carbon monoxide (CO) poisoning. CO poisoning is the leading cause of injury and death by poisoning worldwide, with about 40,000 people treated in the U.S. annually. Brain damage occurs – days to weeks later – in half of the patients with a serious case of CO poisoning. The physiological causes of this delayed decline were not well understood until now. A team led by Stephen R. Thom, MD, PhD, Professor of Emergency Medicine and Chief of Hyperbaric Medicine, at the University of Pennsylvania School of Medicine, report this week online in the Proceedings of the National Academies of Sciences, that CO causes profound changes in myelin basic protein (MBP) – a major protein constituent of myelin, the protective sheath surrounding neurons. Using an animal model, they showed that the CO-induced changes in MBP set into motion an autoimmune response in which lymphocytes, triggered to eliminate altered MBP, continue to attack normal MBP. Specifically, the researchers found that by-products of CO metabolism in the brain alter the charge and structure of MBP. "These changes in MBP have also been demonstrated in multiple sclerosis, which is why we paralleled the study along those lines," says Thom.

DALLAS – – UT Southwestern Medical Center at Dallas researchers have uncovered damage in a specific, primitive portion of the nervous systems of veterans suffering from Gulf War syndrome. UT Southwestern researchers report that damage to the parasympathetic nervous system may account for nearly half of the typical symptoms – including gallbladder disease, unrefreshing sleep, depression, joint pain, chronic diarrhea and sexual dysfunction – that afflict those with Gulf War syndrome. Their findings will be published in the October issue of the American Journal of Medicine and are currently available online. "The high rate of gallbladder disease in these men, reported in a previous study, is particularly disturbing because typically women over 40 get this. It's singularly rare in young men," said Dr. Robert Haley, chief of epidemiology at UT Southwestern and lead author of the new study. The parasympathetic system regulates primitive, automatic bodily functions such as digestion and sleep, while the sympathetic nervous system controls the "fight or flight" instinct.

Although recent reports on mercury have focused on the dangers to humans, some researchers feel that public health could be better guarded if standards were enforced that protect wildlife. Gary Heinz, a research biologist with the U.S. Geological Survey (USGS) at the Patuxent Wildlife Research Center in Laurel, Md., has found that some bird species are much more sensitive than humans to mercury. “To a large extent, researchers in human toxicology ignore the work that is being done in wildlife toxicology,” he says. “The reverse is also unfortunately true.” Human dietary guidelines for mercury range from a high of 1.0 parts per million (ppm) in the United States to a low of 0.4 ppm in Japan. However, birds can show ill effects at much lower dietary concentrations than humans. Mallard ducks, for instance, experience harmful influences to eggs when fed as little as 0.1 ppm of methylmercury, and ring-necked pheasant show effects at 0.2 ppm. Yet, only four species of birds have been well studied, because captive breeding experiments with wild animals are both daunting and expensive, say USGS researchers. Heinz has used direct injection of methylmercury into eggs as a quick and effective means to test chick mortality in 20 bird species. While mallards have increased chick mortality at 0.8–1.0 ppm, the most sensitive species is the white ibis, whose chicks begin dying at methylmercury concentrations of only 0.1 ppm. He also notes that these are mercury levels that birds are likely to encounter in the wild. Copyright © 2004 American Chemical Society

The red Mozambique spitting cobra stiffens, fixing its gaze on the victim's face, which is moving backwards and forwards in front of it. For several seconds it remains erect like this; then its head flashes forwards. For an instant the fangs in front of its pale pink throat are visible in its wide-open mouth, as they squirt the venom at high pressure towards the victim. On the plastic visor two red spiral patterns appear. The eyes behind it look surprisingly unperturbed. "I sprayed the visor beforehand with rhodamine," Katja Tzschätzsch calmly explains, "It's a pigment which dyes liquids red. This makes the traces of venom easier to see." In her undergraduate dissertation the trainee teacher investigated what spitting cobras aim at when spitting. "In the literature it often says: they aim at the eyes," her supervisor Dr. Guido Westhoff, junior lecturer in Professor Horst Bleckmann's team, explains. "However, up to now nobody has investigated it." The cocktail of toxins partly consists of nerve poisons, but also contains components which are harmful to tissue. Through a narrow channel in their fangs the snakes can spray the liquid at high pressure – similar to a bullet in the barrel of a gun. If they manage to hit an eye, the sensitive cornea reacts with severe stinging pain. In the worst case these burns can ultimately lead to blindness.

Researchers have long known that mercury increases mortality and decreases fertility in fish, but the underlying metabolic processes are still unknown. New research posted on the ES&T Research ASAP website (es0483490) helps uncover some of the mystery by examining which genes respond when fish are fed methylmercury (MeHg). Although multiple genes turn on in the muscle and liver to help store and detoxify the metal, the brain appears unresponsive and accumulates high levels of mercury. This leads researchers to believe that neural tissue might be unable to defend itself against this toxic compound. The brains of zebrafish fail to mount a defense against methylmercury. "It was a big surprise when we found that genes in the neural system were not responding," says study author Jean-Paul Bourdineaud, a professor of biochemistry at the University of Bordeaux (France). Previous research has shown that mercury can cause lesions in the brain, and a recent study found that MeHg can decrease the density of neurotransmitters in otters that consume diets heavy in fish contaminated with MeHg. (Environ. Sci. Technol. 2005, 39, 218A) The zebra fish in the study were fed diets that contain MeHg at concentrations similar to those found in wild fish (Environ. Sci. Technol. 2002, 36, 877–883). Thirteen different genes were then tested in liver, muscle, and brain tissue. These genes encode for proteins known to be involved in different functions such as antioxidant defense, metal chelation, DNA repair, and cell death. "Testing this range of genes gives us a toxicological survey of mercury's effects," says Bourdineaud. Copyright © 2005 American Chemical Society

Durham, N.C. -– Duke University Medical Center researchers have found that the naturally occurring marine toxin domoic acid can cause subtle but lasting cognitive damage in rats exposed to the chemical before birth. Humans can become poisoned by the potentially lethal, algal toxin after eating contaminated shellfish. The researchers saw behavioral effects of the toxin in animals after prenatal exposure to domoic acid levels below those generally deemed safe for adults, said Edward Levin, Ph.D. Those effects –- including an increased susceptibility to disruptions of memory -- persisted into adulthood, he said. The findings in rats, therefore, imply that the toxin might negatively affect unborn children at levels that do not cause symptoms in expectant mothers, said Levin. While the researchers note that eating seafood offers significant health benefits, they said their findings suggest that the current threshold of toxin at which affected fisheries are closed should perhaps be lowered. The Federal Drug Administration (FDA) set the current limit based on levels safe for adults, Levin said. "A single administration of domoic acid to pregnant rats had a lasting affect on the performance of their offspring as adults," Levin said. "The consequences are life-long. "The findings suggest we may need to re-evaluate monitoring of waters, shellfish and fish to make sure that the most sensitive parts of the human population are protected from toxic exposure to domoic acid," he continued. © 2001-2005 Duke University Medical Center

ST. PAUL, Minn. – Eighteen years later, people who worked with lead have significant loss of brain cells and damage to brain tissue, according to a new study published in the May 23, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology. The study examined 532 former employees of a chemical manufacturing plant who had not been exposed to lead for an average of 18 years. The workers had worked at the plant for an average of more than eight years. The researchers measured the amount of lead accumulated in the workers' bones and used MRI scans to measure the workers' brain volumes and to look for white matter lesions, or small areas of damage in the brain tissue. The higher the workers' lead levels were, the more likely they were to have smaller brain volumes and greater amounts of brain damage. A total of 36 percent of the participants had white matter lesions. Those with the highest levels of lead were more than twice as likely to have brain damage as those with the lowest lead levels. Those with the highest levels of lead had brain volumes 1.1 percent smaller than those with the lowest lead levels. "The effect of the lead exposure was equivalent to what would be expected for five years of aging,"said study author Walter F. Stewart, PhD.

University of Utah researchers isolated an unusual nerve toxin in an ocean-dwelling snail, and say its ability to glom onto the brain's nicotine receptors may be useful for designing new drugs to treat a variety of psychiatric and brain diseases. "We discovered a new toxin from a venomous cone snail that may enable scientists to more effectively develop medications for a wide range of nervous system disorders including Parkinson's disease, Alzheimer's disease, depression, nicotine addiction and perhaps even schizophrenia," says J. Michael McIntosh. Discovery of the new cone snail toxin will be published Friday, Aug. 25 in The Journal of Biological Chemistry by a team led by McIntosh, a University of Utah research professor of biology, professor and research director of psychiatry, member of the Center for Peptide Neuropharmacology and member of The Brain Institute. McIntosh is the same University of Utah researcher who – as an incoming freshman student in 1979 – discovered another "conotoxin" that was developed into Prialt, a drug injected into fluid surrounding the spinal cord to treat severe pain due to cancer, AIDS, injury, failed back surgery and certain nervous system disorders. Prialt was approved in late 2004 in the United States and was introduced in Europe last month.

Brian Vastag A mercury-containing vaccine preservative is not associated with problems in speech, intelligence, memory, coordination, attention, or other measures of childhood development, a large new study finds. Child-health experts say that the results should allay concerns that thimerosal, a preservative first added to vaccines in the 1930s, affects children's brains. "The study was enough to convince me that this small amount of mercury ... was not harmful to the children," says Michael Goldstein, vice president of the St. Paul, Minn.–based American Academy of Neurology. "I think it's one more piece of evidence that thimerosal doesn't have any negative association with health outcomes," says Penelope Dennehy, professor of pediatrics at the Brown University School of Medicine in Providence, R.I. The study, funded by the Centers for Disease Control and Prevention (CDC) in Atlanta, enrolled 1,047 children, from 7 to 10 years old, whose health needs had been covered from birth by four health maintenance organizations. The researchers combed the health plans' records to assess how much thimerosal each child received through the first 7 months of life. ©2007 Science Service

Nora Schultz There is a cure for zombies after all – if you are a cockroach. A new study has shown that cockroaches that turned into zombies after being stung by a parasitic wasp can be revived with an antidote. Cockroaches can lose their ability to walk when stung by jewel wasps (Ampulex compressa) – the females of which use the cockroaches to feed their young. The wasp, being much smaller than the cockroach, has evolved a fine sting that can deliver a venom cocktail directly into the cockroach’s brain. The poisons effectively turn the cockroach into a zombie. The cockroach is not entirely paralysed, but loses its ability to escape. The wasp then grabs it by the antennae and pulls it into its burrow and lays an egg on its abdomen. The cockroach sits still while the wasp's larva hatches, chews a hole into its belly, and slowly eats its living host from the inside over a period of eight days. To find out if he could revive the cockroaches, Frederic Libersat from Ben-Gurion University in Be'er Sheva, Israel, injected stung zombie cockroaches with candidate chemicals that resembled various neurotransmitters in the brain. Journal reference: The Journal of Experimental Biology (vol 210, p 4411) © Copyright Reed Business Information Ltd.

Links for keyword: Neurotoxins