Bulletin Board August 20, 2010 Contact us

Smog Might Trigger Cell Death in the Heart, Study Finds

2010-07-27

At the recent American Heart Association’s Basic Cardiovascular Sciences 2010 Scientific Sessions -- Technological and Conceptual Advances in Cardiovascular Disease, researchers reported that an earlier study in rats provided the first direct indication that a major component of smog might trigger cell death in the heart. The study found that exposure to ground-level ozone over several weeks increased the activity of a substance that triggers cell death in the heart. Ozone (O3) is a highly reactive gas made up of three oxygen molecules. In the upper atmosphere, it protects Earth from the sun’s radiation. However, O3 becomes a major component of smog when it forms near the ground through reactions between sunlight, nitrogen oxides and hydrocarbons from fossil fuels and industrial processes. “Several epidemiological studies have linked air pollution to the development of cardiovascular disease, but air pollution contains hundreds of chemicals and those studies were unable to separate out the effects of individual components,” said Rajat Sethi, Ph.D., an assistant professor in the Department of Pharmaceutical Sciences at the Texas A&M Health Science Centre Irma Lerma Rangel College of Pharmacy in Kingsville, Texas. “Our study looked for direct evidence of the role of ozone alone in cardiac dysfunction by creating a controlled environment.” During the study, the researchers tested four groups of 10 rats living in clear plastic-glass boxes. The first two groups were exposed for eight hours a day to 0.8 parts per million (ppm) of O3 for either 28 or 56 consecutive days. The other two groups were exposed to 28 days or 56 days of clean, filtered air for eight hours per day. After the eight hours of testing, all the rats experienced 16 hours of clean air overnight. The results demonstrated that the hearts of the O3-exposed rats had increased levels of tumour necrosis factor-alpha (TNF α), an indication of inflammation compared to hearts of the control rats. Increased TNF α levels have been linked to a drop in levels of a heart-protective protein called Caveolin-1 (Cav1). Scientists believe Cav1 protects the heart by binding to a chemical called p38MAPK alpha (p38MAPK α), which is known to be a cell death signalling chemical, Sethi said. The researchers found that Cav1 levels decreased in the hearts of rats exposed to O3 compared to the hearts of control rats who breathed filtered air. “We believe the decreased levels of Cav1 make more unbound p38MAPK α available for telling the heart cells to die. That link between Cav1 and O3 has never been shown in the heart,” Sethi said.

Science Daily, 22 July 2010 http://www.sciencedaily.com

Zinc sprays dull sense of smell in some users

2010-07-27

New research has concluded that homeopathic zinc nasal sprays don’t fight colds, and they probably cause some people to lose their sense of smell. “Increased Food and Drug Administration oversight of homeopathic medications is needed to monitor the safety of these popular remedies,” Drs. Terence M. Davidson and Wendy Smith of the University of California, San Diego, and the Veterans Affairs San Diego Health System write in the July issue of the Archives of Otolaryngology -- Head and Neck Surgery. Homeopathic remedies contain tiny amounts of certain substances mixed with inactive ingredients. While the FDA requires people dispensing homeopathic drugs for “serious disease conditions” to be licensed, Davidson and Smith note, regulation of over-the-counter products is virtually nonexistent. While over-the-counter zinc gluconate sprays remain a popular cold remedy, a number of well-designed studies have shown that the sprays don’t work, the researchers point out. There’s also growing evidence that zinc nasal sprays could dull people’s sense of smell, or even eliminate it, possibly permanently, they add. During the new study, the researchers investigated whether zinc sprays could actually be causing users to lose their sense of smell by examining 25 people who lost their sense of smell soon after using zinc gluconate gel. All had sought care at the university’s Nasal Dysfunction Clinic. In addition, they reviewed the medical literature on the relationship between zinc use and olfactory problems. The researchers used a set of nine requirements known as the Bradford Hill Criteria to determine whether zinc caused the patients’ olfactory problems. Researchers developed the criteria in 1965 so they could test whether tobacco smoking causes lung cancer without having to perform a large - and unethical - study in which they assigned some people to smoke. The seven criteria require that several people in different parts of the world see the same relationship, which the effect occurs soon after the potential cause, and other findings. The researchers discovered that the zinc-olfaction relationship fulfilled all nine criteria. For example, people report a loss of sense of smell within minutes to hours after using the spray; also, the relationship between zinc use and loss of sense of smell has been reported by several independent groups of researchers. “Based on our analysis, it appears evident that intranasal zinc can and does cause anosmia,” the clinical term for loss of sense of smell, the researchers say. Right now, they add, homeopathic remedies aren’t required to follow FDA rules on expiration dating or laboratory testing to confirm that they actually contain the active ingredients they claim, at the stated strength. “Protecting our patients from the potential risks of intranasal zinc medications and other homeopathic drugs, especially ones with limited therapeutic benefit, should be a high priority of the FDA,” Davidson and Smith conclude.

Reuters Health, 21 July 2010 http://www.reuters.com/news/health

Gulf Oil Dispersants Unlikely to Be Endocrine Disruptors and Have Relatively Low Cell Toxicity, Tests Find

2010-07-27

Government researchers have reported that eight of the most commonly used oil dispersants used to fight oil spills, such as the massive episode in the Gulf of Mexico, appear unlikely to act as endocrine disruptors -- hormone-like substances that can interfere with reproduction, development, and other biological processes. In addition, the tested dispersants had a relatively low potential for cytotoxicity (cell death), with JD-2000 and SAF-RON GOLD showing the least potential. The researchers were from the U. S. Environmental Protection Agency and the National Institutes of Health Chemical Genomics Centre. The study was published in the journal Environmental Science & Technology. Richard Judson and colleagues note that more than 1.5 million gallons of dispersants have been used so far in the Deepwater Horizon spill. These detergent-like chemicals break up oil slicks into small drops. Scientists are concerned that some dispersants contain ingredients that turn into endocrine disruptors in the environment, and could harm marine mammals, fish, and humans. But only limited toxicity testing data is available on currently-used dispersants, and this is only results from the first round of EPA dispersant testing, they state. With an urgent need for such information in the Deepwater Horizon spill, the scientists applied a rapid screening method using mammalian cells to determine the eight dispersants’ potential to act as endocrine disruptors and relative toxicity to living cells. The dispersants included a type widely being used to treat the Gulf oil spill. None of the substances showed significant endocrine disruption activity and cytotoxicity was not seen until dispersants were tested at concentrations above 10 parts per million, the scientists said. However, they note that “there are other routes by which chemicals can cause endocrine disruption, as well as other types of toxicity that have not been tested for here.”

Science Daily, 22 July 2010 http://www.sciencedaily.com

Chemicals higher, thyroid hormone lower in pregnant women near e-waste recycling

2010-07-27

Yet another study has raised concerns regarding e-waste recycling and its effects on human health following a new report, which found that pregnant women in China who live nearer the facilities have higher levels of toxic chemicals and depressed levels of thyroid hormones. Pregnant women who live in areas close to electronic waste dismantling sites have higher exposures to persistent organic pollutants and depressed thyroid hormone levels than those who live farther away from the facilities, a new study that compares women in two regions of China, has found. Despite the fact that they have no interactions with the e-waste facility, the recycling activities affect the women living adjacent to the sites. This study raises concerns about e-waste practices and health effects on both the mothers and the developing foetuses. This is the first study to evaluate the levels of these three groups of pollutants in people who live near e-waste recycling sites and to determine their effect on thyroid hormone levels. The results of this study mostly agree with findings from the few prior studies that have also looked at the effects of the chemical groups – either alone or in pairs – on thyroid hormones. PCBs and PBDEs are widely-used chemicals found in electronic products. PCDDs/Fs are typically formed when the electronic products containing these chemicals burn – as sometimes happens during their gutting and recycling. These chemicals have been either banned or phased out from use due to persistence, bioaccumulation and toxicity concerns. Yet, the compounds are still present in residential areas and in consumer products. Electronic waste recycling – including burning, acid leaching and dismantling – can release the pollutants into the air, water and soil where people can be exposed to high levels. All of the chemicals measured affect thyroid regulation in animal exposure studies. Several of these studies document significant associations between exposure to the contaminants and depression of thyroid hormone levels in both children and adults. Steady thyroid hormone levels are critical to the developing foetus, particularly for physical and mental development. Low thyroid hormone levels can cause delays and brain and nervous system problems.
During the study, the researchers examined 50 pregnant women who lived in two different regions in southeast China for at least five years. One region is a well-known e-waste recycling area (zone A), in which recycling has been going on for more than 25 years. The second region represents a control reference site (zone B) and is located more than 250 kilometres away from the first region. Researchers measured the levels of about 17 chlorinated dioxins (i.e. PCDDs and PCDFs), six polychlorinated biphenyls (PCBs) and six polybrominated diphenyl ethers (PBDEs) in cord blood collected during delivery. Thyroid hormone levels – T3, thyroxine (T4) and thyroid stimulating hormone (TSH) – were measured in the women’s blood samples taken during the sixteenth week of pregnancy. The results demonstrated that in general, women living near the recycling facilities had higher body burdens – and thus, higher exposures – to all three chemical classes than the women who lived farther away. Median concentrations of PCDDs/Fs, PCBs and PBDEs in cord blood collected from those who live close were 3 times, 5.4 times and 1.4 times higher, respectively, than the levels measured in cord blood collected from women who lived farther away. Furthermore, total thyroxine and thyroid stimulating hormone (TSH) were significantly lower in women nearer the recycling activities. The researchers found that as PCDDs/Fs and PCBs levels increased, levels of T4 decreased. This association was statistically significant. The researchers concluded that the findings from the latest study suggest that further research into human health effects of both employees in e-waste sites and for people living in cities with e-waste facilities from exposure to chemicals released during e-waste practices is warranted.

Environmental Health News, 20 July 2010 http://www.environmentalhealthnews.org/

Recreational Pool Disinfectants Linked to Health Problems

2010-07-27

Splashing around in a swimming pool on a hot summer day may not be as safe as you think. According to the findings from a new study by researches at the University of Illinois, the application of disinfectants in recreational pools is linked to previously published adverse health outcomes such as asthma and bladder cancer. Each year, 339 million visits take place at pools and water parks across the United States. Not only is swimming fun, but it’s also the second most popular form of exercise in the country. Because of this, disinfection of recreational pools is critical to prevent outbreaks of infectious disease. However, Michael Plewa, U of I professor of genetics, said negative outcomes can occur when disinfection by-products form reactions with organic matter in pool water. Pool water represents extreme cases of disinfection that differ from the disinfection of drinking water as pools are continuously exposed to disinfectants. “All sources of water possess organic matter that comes from decaying leaves, microbes and other dead life forms,” Plewa said. “In addition to organic matter and disinfectants, pool waters contain sweat, hair, skin, urine, and consumer products such as cosmetics and sunscreens from swimmers.” These consumer products are often nitrogen-rich, causing concern that they may contribute to the generation of nitrogenous disinfection by-products, Plewa added. When mixed with disinfectants, these products may become chemically modified and converted into more toxic agents. These disinfection by-products can mutate genes, induce birth defects, accelerate the aging process, cause respiratory ailments, and even induce cancer after long-term exposures.

In this study, collections from public pools and a control sample of tap water were evaluated to identify recreational water conditions that could be harmful to your health. During the new study, a systematic mammalian cell genotoxicity analysis was used to compare the water samples. Plewa said this sensitive DNA technology examined genomic damage in mammalian cells, allowing researchers to investigate damage at the level of each nucleus within each cell. The study compared different disinfection methods and environmental conditions. The findings proved that all disinfected pool samples exhibited more genomic DNA damage than the source tap water, Plewa said. “Care should be taken in selecting disinfectants to treat recreational pool water,” Plewa advised. “The data suggest that brominating agents should be avoided as disinfectants of recreational pool water. The best method to treat pool waters is a combination of UV treatment with chlorine as compared to chlorination alone.” Plewa recommends that organic carbon be removed prior to disinfection when the pool water is being recycled. Furthermore, swimmers can help reduce the genotoxicity of pool water by showering before entering the water. Pool owners should also remind patrons about the potential harm caused by urinating in a pool. These simple steps can greatly reduce the precursors of toxic disinfection by-products, Plewa said.

Science Daily, 22 July 2010 http://www.sciencedaily.com
New membrane makes fresh water from sea and sewage feasible

2010-07-27

A special membrane turns salty sea water into fresh water, paving the way for large-scale desalination that would provide desperately needed drinking water. The technology, developed by researchers at Yale University, can clean and purify water from oceans, salty ground water or sewage water with far less energy input than currently is required to do a similar job. The membrane may be a big step forward in reaching the goal of reliable and affordable sources of fresh water. Finding sustainable sources of clean drinking water is a major global challenge, especially in most of the developing world. The need is apparent in both urban areas, due to growing population and demand, and rural regions, where sometimes scarce water supplies are quickly drying up. As fresh water becomes more scarce, desalination and filtering will be increasingly necessary to satisfy the world’s unquenchable thirst for this precious commodity. Yet, neither of the existing desalination technologies – distilling sea water vapours by boiling then collecting the water vapours or reverse osmosis where water is pushed through membranes to filter the salt – are feasible on a large scale. Both require high amounts of energy to either boil the water or create pressure. A newer approach does not require external heat or pressure but lacks an adequate membrane to filter the water. The technique uses a mixture of dissolved carbon dioxide and ammonia gas in water on one side and salty or dirty water on the other side of the membrane. The gas/water mixture draws the clean water through the membrane and leaves the salt and dirt on the other side. A small amount of heat is then applied to drive off the carbon dioxide and ammonia, leaving just pure, fresh water. However, no current membranes can stand up to the ammonia. Now, researchers report that they have developed one – a thin-film composite forward osmosis membrane. They describe the new development in the journal Environmental Science and Technology. The membrane is permeable enough to allow water to flow freely through it but resistant enough to keep the ammonia and chemicals in sewage from passing through it. This landmark development is a beginning. More research is required to bring down the costs of the membranes and make this technology accessible in all parts of the world.

Environmental Health News, 20 July 2010 http://www.environmentalhealthnews.org/

Key Finding: Many Pathogenic Fungi Use the Same Entrance to Invade Host Cells

2010-07-27

In a new study, researchers have discovered that many deadly pathogens use the same protein to gain access to the cells of a potential host. The new findings could have implications for blocking infections by agents ranging from wheat rust to malaria. Pathogenic fungi, such as flax rust and soybean rust, and similar pathogens known as oomycetes, such as the organism behind the Irish potato famine and sudden oak death, make similar proteins to disarm their hosts’ defences. But to work, these effector proteins need to first make their way inside of a cell. Up until now, researchers did not know, in the first place, how these compounds were able to break in. The new study, published in the journal Cell, describes how these blights do it. To infect a plant, pathogenic fungi and oomycetes make a protein called RXLR—a type of effector protein—which enters plant host cells and blocks the plant’s defences. However, the new research shows that both of these types of organisms are able to insert their effector proteins inside the cell by binding with a single type of lipid on the host cell’s surface. This union allows the effector protein to be carried into the cell through the cell wall, where it can start doing damage. “Even though they’re very different, they’re using a similar mode of entry,” says Shiv Kale, a National Science Foundation graduate research fellow at Virginia Tech’s Virginia Bioinformatics Institute and lead author of the new paper, of the various plant pathogens. The “key” that the pathogens use to get into host cells is a lipid known as phosphatidylinositol-3-phosphate (or PI-3-P). That such different organisms would make use of a single lipid was a surprise to Kale and his colleagues. And although PI-3-P had been described before, “that lipid is predominantly on the inside of the cell,” Kale says, so finding it on the exterior surface of the cells was “really exciting.” Even though the universality of the lipid use was unexpected, “it makes sense from an evolutionary standpoint,” Kale explains. If the single key could give pathogens access to a multitude of hosts, the talent would be worth keeping around, leading Kale to conclude that the pathogens’ mode of entry is probably “ancient and highly conserved.” The single common technique for entry could be salutary for humans and the crops we depend on, though, as researchers in agriculture and medicine strive to find the best ways to block fungal and oomycete infections.
“The finding is no doubt a breakthrough in host–pathogen interaction,” Takao Kasuga and Lynn Epstein, both of the Department of Plant Sciences at the University of California, Davis, noted in a joint e-mail. “We now know how pathogens’ effector proteins are delivered into host cells.” These lipid receptors were not just found on the surface of the plant cells tested by Kale and his colleagues, but on some animal cells as well—including human lung epithelial cells. Kale is hopeful that the findings might someday be put to use in new treatments that could suppress PI-3-P and block the pathogen’s path. “It seems that if you can find a target for this entry mechanism, you could develop a therapeutic,” he says. Such a medication might be useful to patients who have compromised immune systems and fall prey to fungal infections that healthier individuals can usually fight off, such as those with AIDS who are more susceptible to cryptococcal meningitis, a fungal infection that can attack the nervous system. However, the new data did not illuminate whether any of the host’s biological processes would be interrupted if the binding capabilities of their cells’ external PI-3-P were inhibited, Kale says. And not everyone is sure blocking the host’s binding lipid is going to be a simple approach. The substance in question is “a ubiquitous and extremely important part of the cell membrane,” Kasuga and Epstein noted. “Manipulating and blocking of effector–PI-3-P interactions without interfering with PI-3-P functions in healthy cells may be a challenge.” More broadly, the findings could help to shed light on other scourges, such as malaria. Red blood cells, which malaria infects, have not been shown to have PI-3-P on their surfaces. Nevertheless, the malaria parasite Plasmodium seems to have developed a similar mechanism for entering the cells, Kale notes. Furthermore, examining various entry methods of pathogens, researchers like Kale hope to zero in on an early, possibly universal step in the infection process. Currently, scientists from various disciplines are designing new trials to start putting these findings to work in agricultural and medical realms. Kale notes that this sort of basic discovery, although minute, is just the kind of jumping-off point many basic science researchers dream of. He hopes that eventually preventive treatments will “have some benefit to humanity because of it.”

Scientific American, 23 July 2010 http://www.sciam.com

Better Sampling Needed in Wastewater Monitoring

2010-07-27

A new study by Australian researchers has shown that improper sampling protocols to detect pharmaceuticals, personal care products, and illicit drugs in sewage can lead researchers to misestimate the chemicals’ concentrations or miss the pollutants altogether. The new study was published in the journal Environmental Science & Technology. Chemical contaminants appear and disappear over time in wastewater, so whether or not researchers detect them depends on when and how frequently scientists collect samples. Scientists want to quantify the flux of pharmaceuticals, personal care products, and illegal drugs through sewage systems to determine how much we release into the environment and to improve sewage plants treatments. However, many scientists lack the instruments that can monitor these contaminants’ dynamics with sufficient time resolution, says environmental engineer Christoph Ort of the University of Queensland in Australia. In a separate study, Ort and colleagues examined 87 recent papers that studied 267 different sewer sites, and found that the authors didn’t cite or heed internationally-accepted sampling practices. Researchers often collected samples too infrequently and then pooled all their samples together for analysis; in doing so, they lost all information about the dynamics of a compound over time and possibly missed pollutants. In the present study, Ort and colleagues illustrate the point by tracking a medical-imaging contrast agent at a sewage treatment plant that served 100,000 inhabitants. Based on how frequently doctors use the chemical, the investigators estimated that at most one or two people in that population would excrete the compound into the sewage system during a weekday. Then, the researchers monitored the wastewater over a four-hour time period. To ensure that they didn’t miss a single toilet flush, they collected 120 samples, each consisting of two minutes of wastewater flow. When they analysed the samples by mass spectrometry, the contrast agent only showed up in 30. If they had sampled less frequently, the scientists may have missed its presence completely. Scientists often resort to improper sampling because of expense or logistical limitations, says chemist Bruce Brownawell at Stony Brook University in New York, but this study highlights its pitfalls: “It makes us vigilant about paying attention to the sampling methods.”

Chemical & Engineering News, 23 July 2010 http://pubs.acs.org/cen/news