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Thousands of the nation’s largest water polluters are outside the Clean Water Act’s reach because the Supreme Court has left uncertain which waterways are protected by that law, according to interviews with regulators. As a result, some businesses are declaring that the law no longer applies to them. And pollution rates are rising. Companies that have spilled oil, carcinogens and dangerous bacteria into lakes, rivers and other waters are not being prosecuted, according to Environmental Protection Agency regulators working on those cases, who estimate that more than 1,500 major pollution investigations have been discontinued or shelved in the last four years. Story continues below ↓advertisement | your ad heredap('&PG=NBCMSN&AP=1089','300','250');The Clean Water Act was intended to end dangerous water pollution by regulating every major polluter. But today, regulators may be unable to prosecute as many as half of the nation’s largest known polluters because officials lack jurisdiction or because proving jurisdiction would be overwhelmingly difficult or time consuming, according to midlevel officials.

To explore how such memories are recorded, the researchers showed ten volunteers three short films and asked them to memorise what they saw. The films were very simple, sharing a number of similar features - all included a woman carrying out an everyday task in a typical urban street, and each film was the same length, seven seconds long. For example, one film showed a woman drinking coffee from a paper cup in the street before discarding the cup in a litter bin; another film showed a (different) woman posting a letter. The volunteers were then asked to recall each of the films in turn whilst inside an fMRI scanner, which records brain activity by measuring changes in blood flow within the brain. A computer algorithm then studied the patterns and had to identify which film the volunteer was recalling purely by looking at the pattern of their brain activity. The results are published in the journal Current Biology. "The algorithm was able to predict correctly which of the three films the volunteer was recalling significantly above what would be expected by chance," explains Martin Chadwick, lead author of the study. "This suggests that our memories are recorded in a regular pattern." Although a whole network of brain areas support memory, the researchers focused their study on the medial temporal lobe, an area deep within the brain believed to be most heavily involved in episodic memory. It includes the hippocampus - an area which Professor Maguire and colleagues have studied extensively in the past. They found that the key areas involved in recording the memories were the hippocampus and its immediate neighbours. However, the computer algorithm performed best when analysing activity in the hippocampus itself, suggesting that this is the most important region for recording episodic memories. In particular, three areas of the hippocampus - the rear right and the front left and front right areas - seemed to be involved consistently across all participants. The rear right area had been implicated in the earlier study, further enforcing the idea that this is where spatial information is recorded. However, it is still not clear what role the front two regions play.

"Exposure to BPA may be harmful during pregnancy; this exposure may permanently affect the fetus," said Hugh S. Taylor, Ph.D., co-author of the study from Yale University School of Medicine in New Haven, Connecticut. "We need to better identify the effects of environmental contaminants on not just crude measures such as birth defects, but also their effect in causing more subtle developmental errors." Taylor and colleagues made this discovery by exposing fetal mice to BPA during pregnancy and examining gene expression and DNA in the uteruses of female fetuses. Results showed that BPA exposure permanently affected the uterus by decreasing regulation of gene expression. These epigenetic changes caused the mice to over-respond to estrogen throughout adulthood, long after the BPA exposure. This suggests that early exposure to BPA genetically "programmed" the uterus to be hyper-responsive to estrogen. Extreme estrogen sensitivity can lead to fertility problems, advanced puberty, altered mammary development and reproductive function, as well as a variety of hormone-related cancers. BPA has been widely used in plastics and other materials. Examples include use in water bottles, baby bottles, epoxy resins used to coat food cans, and dental sealants. "The BPA baby bottle scare may be only the tip of the iceberg." said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Remember how diethylstilbestrol (DES) caused birth defects and cancers in young women whose mothers were given such hormones during pregnancy. We'd better watch out for BPA, which seems to carry similar epigenetic risks across the generations. "

This is the largest nationally representative study to date of the toll taken by sepsis and pneumonia, two conditions often caused by deadly microbes, including the antibiotic-resistant bacteria MRSA. Such infections can lead to longer hospital stays, serious complications and even death. "In many cases, these conditions could have been avoided with better infection control in hospitals," said Ramanan Laxminarayan, Ph.D., principal investigator for Extending the Cure, a project examining antibiotic resistance based at the Washington, D.C. think-tank Resources for the Future. "Infections that are acquired during the course of a hospital stay cost the United States a staggering amount in terms of lives lost and health care costs," he said. "Hospitals and other health care providers must act now to protect patients from this growing menace." Laxminarayan and his colleagues analyzed 69 million discharge records from hospitals in 40 states and identified two conditions caused by health care-associated infections: sepsis, a potentially lethal systemic response to infection and pneumonia, an infection of the lungs and respiratory tract. The researchers looked at infections that developed after hospitalization. They zeroed in on infections that are often preventable, like a serious bloodstream infection that occurs because of a lapse in sterile technique during surgery, and discovered that the cost of such infections can be quite high: For example, people who developed sepsis after surgery stayed in the hospital 11 days longer and the infections cost an extra $33,000 to treat per person. Even worse, the team found that nearly 20 percent of people who developed sepsis after surgery died as a result of the infection. "That's the tragedy of such cases," said Anup Malani, a study co-author, investigator at Extending the Cure, and professor at the University of Chicago. "In some cases, relatively healthy people check into the hospital for routine surgery. They develop sepsis because of a lapse in infection control—and they can die." The team also looked at pneumonia, an infection that can set in if a disease-causing microbe gets into the lungs—in some cases when a dirty ventilator tube is used. They found that people who developed pneumonia after surgery, which is also thought to be preventable, stayed in the hospital an extra 14 days. Such cases cost an extra $46,000 per person to treat. In 11 percent of the cases, the patient died as a result of the pneumonia infection.

"As far as we can tell, this is the first time this type of behavior has been reported in cells that are part of a larger organism," says Peter T. Cummings, John R. Hall Professor of Chemical Engineering, who directed the study that is described in the March 10 issue of the Public Library of Science journal PLoS ONE. The discovery was the unanticipated result of a study the Cummings group conducted to test the hypothesis that the freedom with which different cancer cells move - a concept called motility - could be correlated with their aggressiveness: That is, the faster a given type of cancer cell can move through the body the more aggressive it is. "Our results refute that hypothesis—the correlation between motility and aggressiveness that we found among three different types of cancer cells was very weak," Cummings says. "In the process, however, we began noticing that the cell movements were unexpectedly complicated." Then the researchers' interest was piqued by a paper that appeared in the February 2008 issue of the journal Nature titled, "Scaling laws of marine predator search behaviour." The paper contained an analysis of the movements of a variety of radio-tagged marine predators, including sharks, sea turtles and penguins. The authors found that the predators used a foraging strategy very close to a specialized random walk pattern, called a Lévy walk, an optimal method for searching complex landscapes. At the end of the paper's abstract they wrote, "...Lévy-like behaviour seems to be widespread among diverse organisms, from microbes to humans, as a 'rule' that evolved in response to patchy resource distributions." This gave Cummings and his colleagues a new perspective on the cell movements that they were observing in the microscope. They adopted the basic assumption that when mammalian cells migrate they face problems, such as efficiently finding randomly distributed targets like nutrients and growth factors, that are analogous to those faced by single-celled organisms foraging for food. With this perspective in mind, Alka Potdar, now a post-doctoral fellow at Case Western Reserve University and the Cleveland Clinic, cultured cells from three human mammary epithelial cell lines on two-dimensional plastic plates and tracked the cell motions for two-hour periods in a "random migration" environment free of any directional chemical signals. Epithelial cells are found throughout the body lining organs and covering external surfaces. They move relatively slowly, at about a micron per minute which corresponds to two thousandths of an inch per hour. When Potdar carefully analyzed these cell movements, she found that they all followed the same pattern. However, it was not the Lévy walk that they expected, but a closely related search pattern called a bimodal correlated random walk (BCRW). This is a two-phase movement: a run phase in which the cell travels primarily in one direction and a re-orientation phase in which it stays in place and reorganizes itself internally to move in a new direction. In subsequent studies, currently in press, the researchers have found that several other cell types (social amoeba, neutrophils, fibrosarcoma) also follow the same pattern in random migration conditions. They have also found that the cells continue to follow this same basic pattern when a directional chemical signal is added, but the length of their runs are varied and the range of directions they follow are narrowed giving them a net movement in the direction indicated by the signal.