There are beneficial as well as harmful bacteria. Now it seems that "good" ones can save patients from infection by "bad ones," according to a Hebrew University researcher. Mark Spigelman, a visiting professor at the faculty's Sanford Kuvin Center for the Study of Infectious and Tropical Diseases, looked at the deadly MRSA (methacillin resistant Staphylococcus aureus) bacteria found almost only in hospitals. Spigelman, a visiting professor at University College London, argues in the on-line edition of the Annals of the Royal College of Surgeons of England that the stress on antibiotics and scrubbing with antiseptic soap may actually create an opportunity for the more virulent bacteria to attack patients. This is so because these "preventive" measures destroy beneficial bacteria, while the more "nasty" bacteria are often able to survive by adapting to the pharmacological weapons used against them. Since different strains of bacteria do not generally occupy the same surfaces, it would be better, argues Spigelman, to allow "good" bacteria to live in the hospital environment, thus creating a kind of natural shield against the deadlier strains. To test his hypothesis, Spigelman suggests experimenting with antibiotic-free hospitals in which harmless bacteria are free to exist and in which there would be no environmental "incentive" for the more virulent strains to develop. Any patients needing antibiotics would be transferred to hospitals where those are in use. Along the same lines, he suggests that when doctors finish washing their hands with antiseptics, they plunge them into a solution saturated with harmless bacteria - for example bioactive yogurt. The same approach should perhaps be applied to patients' tissues that are to be exposed to surgery. Admitting that his ideas may sound absurd, Spigelman notes that MRSA has become widespread in hospitals - including those in Israel - where the most advanced antibiotics and rigorous antiseptic measures are taken. One must ask, says Spigelman, why more of the same doesn't seem to be working. THYROID DRUG CUTS RISK OF COLON CANCER Long-term use of L-thyroxin, the main hormone secreted by the thyroid gland, reduces the risk of colorectal cancer by half, according to an Israeli study presented at the recent American Association for Cancer Research meeting in Baltimore. If L-thyroxin, commonly used to treat hypothyroidism, is taken for five or more years, there is a significantly reduced risk of colorectal cancer in male and female patients of all ages, origins and religions. It seems most effective, however, in Jewish females aged 65 and older and European-American born participants, which were the largest study sub-populations. Researchers from the Carmel Medical Center, the Technion's Rappaport Faculty of Medicine and Clalit Health Services' National Cancer Control Center in Haifa, along with colleagues at the University of Michigan, conducted a population-based case-control study of patients in northern Israel who had a diagnosis of colorectal cancer between 1998 and 2004 and controls matched according to age, sex, clinic and ethnic group. Protection against colorectal cancer was seen with the use of L-thyroxin in both the right and left colon as well as the rectum. Use of L-thyroxin was protective even after adjusting for patients' use of aspirin, non-steroidal anti-inflammatory and statin drugs, first-degree family history of cancer, level of sports activity and amount of vegetable consumption. Lead author Dr. Gad Rennert said that "we believe that knowledge about the role of L-thyroxin could lead to development of a potential preventive treatment against this deadly disease." Studies have shown that right-sided colon cancer is associated with an increased risk of thyroid cancer, and a predisposition to thyroid cancer is a well-described feature of familial adenomatous polyposis - a disease involving the formation in the colon and rectum of benign polyps that become cancerous if left untreated. Also, hypothyroidism is known to impair colonic motility, suggesting its relation to colon cancer. NO EARLY TO BED If your teenagers seem unable to fall asleep until late at night, they may not be to blame. A new sleep medicine study has found that the "sleep pressure" rate - the biological trigger that causes sleepiness - changes in adolescence. Published in the November issue of Sleep, the study suggests that as children mature, the internal, chemically driven pressure to sleep builds up more slowly, so teens really aren't sleepy until later in the evening. "We've found another part of the story - the mechanism in the brain that builds up sleep pressure is working at a different rate in adolescents than in pre-pubescent children," says coauthor Dr. Mary Carskadon, a psychiatrist and director of the sleep lab at Brown University Medical School. Numerous studies have found that as children go through puberty, they struggle against going to bed early - a phenomenon attributed to changes in their brain's internal clock. The results show that "early to bed, early to rise" presents a real challenge for adolescents. The authors suggest that the shift in sleep-cycles for teenagers helps physically prepare them for performing tasks under sleep deficits that are common in modern adults.