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Archive - 2010

Date

February 10th

Owls Chattier on Moonlit Nights

An international team of scientists from Spain, Finland, and Portugal recently discovered that eagle owls (Bubo bubo) communicate with each other using a patch of white throat plumage that is repeatedly exposed during each call and is only visible during vocal displays. The scientists found that the owls use moonlight to increase the conspicuousness of this visual signal during their call displays. Call displays were found to be directly influenced by the amount of moonlight, with silent nights being more frequent during periods with no moonlight versus those with moonlight. Furthermore, high numbers of calling bouts were more frequent at moonlight. Finally, call posts were located on higher positions on moonlit nights. The researches said that their results support the idea that moon phase affects the visual signaling behavior of this species, and provide a starting point for examination of this method of communication by nocturnal species. This work was reported on January 20, 2010, in PLoS ONE. [PLoS ONE article]

Bees Prefer Nicotine and Caffeine in Nectar

Bees prefer nectar with small amounts of nicotine and caffeine over nectar that does not contain these substances at all, according to results of a recent study from the University of Haifa in Israel. “This could be an evolutionary development intended, as in humans, to make the bee addicted,” stated Dr. Ido Izhaki, one of the researchers who conducted the study. The researchers emphasized, however, that their study has proved a preference, not an addiction, and they are currently conducting additional studies to determine if bees do indeed become addicted to nicotine and caffeine. Flower nectar is primarily composed of sugars, which provide energy for the potential pollinators. But the floral nectar of some plant species also includes small quantities of substances known to be toxic, such as caffeine and nicotine. Nicotine is found naturally in floral nectar at a concentration of up to 2.5 milligrams per liter, primarily in various types of tobacco trees. Caffeine is found at concentration levels of 11-17.5 milligrams per liter, mostly in citrus flowers. In the nectar of grapefruit flowers, however, caffeine is present in much higher concentrations, reaching 94.2 milligrams per liter. In order to examine whether bees prefer the nectar containing caffeine and nicotine, the researchers offered artificial nectar that contained various natural sugar levels and various levels of caffeine and nicotine, alongside “clean” nectar that included sugar alone. The caffeine and nicotine concentrations ranged from the natural levels in floral nectar up to much higher concentrations than found in nature. The results showed that bees clearly prefer nectar containing nicotine and caffeine over the “clean” nectar. The preferred nicotine concentration was 1 milligram per liter, similar to that found in nature.

February 9th

Experimental Drug Targets Cognitive Defects in Huntington’s Disease

The experimental drug dimebon (latrepirdine), being developed for patients with Alzheimer's disease and long used as a hay fever treatment in the former Soviet Union, appears well tolerated and may improve cognition (thinking, learning, memory skills) among individuals with Huntington's disease, according to results of an early-stage clinical trial. "This is the first clinical trial that has focused on what is perhaps the most disabling aspect of the disease," said University of Rochester Medical Center neurologist Dr. Karl Kieburtz, the lead author of the study. "While more investigation needs to be done, these results are encouraging and show, for the first time, a statistically significant benefit in terms of improved cognitive function in patients with Huntington's disease." The dominantly inherited genetic disease, which killed famous American folk singer Woody Guthrie, is a progressive neurodegenerative disorder that impacts movement, behavior, and cognition, and generally results in death within 20 years of the disease's onset. The disease steadily erodes a person's memory and his/her ability to think and learn. Over time, this cognitive impairment contributes to the loss of the ability to work and perform the activities of daily life. There are no treatments currently available that effectively alter the course of the disease or improve cognition. The only approved therapy for Huntington's disease, tetrabenazine, treats only motor symptoms and does not alter the course of the disease or prevent cognitive decline. Abnormalities in mitochondria have been implicated in the development of Huntington's disease and dimebon stabilizes and improves mitochondrial function.

Existing Drug May Be Useful in Treating 37 Million with River Blindness

Researchers at The Scripps Research Institute, together with colleagues, have reported that a drug (closantel) currently used as the standard treatment for sheep and cattle infected with liver fluke may be useful in treating river blindness, a tropical disease that is the world's second leading infectious cause of blindness for humans (the leading cause is trachoma, caused by infection with Chlamydia trachomatis). Dr. Kim Janda, an author of the new report, said that there is an urgency to fighting the infection that leads to river blindness, which is also known as onchocerciasis. Despite several eradication efforts, the disease affects more than 37 million people in Africa, Central and South America, and Yemen. "Victims of onchocerciasis suffer severe skin lesions, musculoskeletal pain, and various stages of blindness," said Dr. Janda, adding that patients also experience decreased body mass index, decreased work productivity, and social stigmatization. The new research shows that clostanel has the potential to inhibit the molting process of the parasite (Onchocerca volvulus) that causes river blindness. "We think this finding holds terrific potential for the treatment of river blindness, one of 13 recognized neglected tropical diseases," said Dr. Christian Gloeckner, the first author of the study. River blindness is caused by thread-like filarial nematode worms, O. volvulus, which are transmitted among humans through the bite of a black fly. The worms then multiply and spread throughout the body. When the worms die, they cause a strong immune system response that can destroy surrounding tissue, including that of the eye. Currently, the only drug available for mass treatment of river blindness is ivermectin, and it now appears that resistance to that drug is emerging.

February 7th

First Genetic Variants Associated with Biological Aging in Humans

Scientists announced that they have identified, for the first time, definitive genetic variants associated with biological aging, as indicated by mean telomere length, in humans. An international team, led by researchers at the University of Leicester and King’s College London, analyzed more than 500,000 genetic variations across the entire human genome to identify the aging-related variants which are located near a gene called TERC, a gene that is known to play a role in telomere length. Telomeres are capping-like structures located at the tips of chromosomes. “Individuals are born with telomeres of certain length and in many cells telomeres shorten as the cells divide and age,” said Dr. Nilesh Samani, a co-leader of the project. “Telomere length is therefore considered a marker of biological aging." Dr. Samani explained that there are two forms of aging--chronological aging, i.e., how old you are in years, and biological aging whereby the cells of some individuals are older (or younger) than suggested by their chronological age. “In this study,” Dr. Samani said, “what we found was that those individuals carrying a particular genetic variant had shorter telomeres, i.e., looked biologically older. Given the association of shorter telomeres with age-associated diseases, the finding raises the question whether individuals carrying the variant are at greater risk of developing such diseases." Dr. Tim Spector, also a co-leader of the project, noted, “What our study suggests is that some people are genetically programmed to age at a faster rate. The effect was quite considerable in those with the variant, equivalent to between 3-4 years of 'biological aging’ as measured by telomere length loss.

Serotonin Inhibitor Appears to Cure Osteoporosis in Rodents

An investigational drug that inhibits serotonin synthesis in the gut effectively cured osteoporosis in mice and rats when administered orally once a day, according to a report by an international team led by researchers from the Columbia University Medical Center. "New therapies that inhibit the production of serotonin in the gut have the potential to become a novel class of drugs to be added to the therapeutic arsenal against osteoporosis," said Dr. Gerard Karsenty, Chair of the Department of Genetics and Development at the Columbia University College of Physicians and Surgeons, and a senior author of the report. "With tens of millions of people worldwide affected by this devastating and debilitating bone loss, there is an urgent need for new treatments that not only stop bone loss, but also build new bone. Using these findings, we are working hard to develop this type of treatment for human patients." The current study followed up on an earlier report, in Cell (November 28, 2008), by Dr Karsenty’s group and colleagues, showing that serotonin released by the gut inhibits bone formation, and that regulating the production of serotonin within the gut affects the formation of bone. Prior to that discovery, serotonin was primarily known as a neurotransmitter acting in the brain. Yet, 95 percent of the body's serotonin is found in the gut, where its major function is to inhibit bone formation (the remaining 5 percent is in the brain, where it regulates mood, among other critical functions). By turning off the intestine's release of serotonin, the team was able, in the new study, to cure osteoporosis in rodents that had undergone menopause. The results demonstrated that osteoporosis was prevented from developing, or when already present, could be fully cured.

February 5th

HPV Vaccines May Reduce Wide Range of Genital Diseases

High-coverage human papillomavirus (HPV) vaccinations among adolescent and young women may result in a rapid reduction of genital warts, cervical cell abnormalities, and diagnostic and therapeutic procedures, researchers report in a new study published online February 5 in the Journal of the National Cancer Institute. Some of these genital abnormalities are precursors of cervical, vulvar, and vaginal cancers. The study focused on 17,622 women enrolled in one of two randomized, placebo-controlled, efficacy trials for the HPV6/11/16/18 vaccine. All women underwent cervicovaginal sampling and Pap testing. In the group representing uninfected women, vaccination was up to 100% effective in reducing the risk of HPV16/18-related high-grade cervical, vulvar, and vaginal lesions and in reducing the risk of HPV6/11-related genital warts. In the group representing the general population, vaccination reduced the risk of any lesion, genital warts, Pap abnormalities, and definitive therapy, irrespective of HPV type. The reduction in risk was statistically significant. "Our results provide strong evidence to suggest that the ongoing HPV vaccination programs in adolescent girls and young women will result within a few years in a notable reduction of genital warts, cervical cytological abnormalities, and diagnostic and therapeutic procedures related to precursor lesions in the cervix, vulva, and vagina," the authors wrote. "It is anticipated that these reductions will eventually translate into lower rates of cancer of the cervix, vulva, and vagina." [Press release] [JNCI abstract]

Artificial Pancreas System Shows Promise in Type 1 Diabetes

In a study in children and teenagers with type 1 diabetes, researchers have shown that using a first-generation artificial pancreas system overnight can lower the risk of low blood sugar emergencies while sleeping, and at the same time improve diabetes control. The closed-loop system combined commercially available blood glucose sensors and insulin pumps, controlled by a sophisticated computer program that determined insulin dosage based on blood glucose levels while participants slept. Maintaining recommended blood sugar levels overnight is a major issue for people with type 1 diabetes--and particularly for the families of children with diabetes--because of the possibility of blood glucose dropping dangerously low during sleep and going unnoticed, which can lead to seizures, coma, and in some cases be fatal. Notably, the study showed that the children and teenagers spent twice as much time during the night within targeted blood glucose levels when their diabetes was regulated with the artificial pancreas system than when they followed conventional "manual" therapy—and low blood sugars were minimized. "Without a doubt, the biggest worry for parents of kids with type 1 diabetes is that their child will have a low blood sugar emergency during the night, when they're hard to identify," said Dr. Aaron Kowalski, Assistant Vice President of Metabolic Control at the Juvenile Diabetes Research Foundation (JDRF) and Director of the JDRF Artificial Pancreas Project. "This study is proof of principle that diabetes in kids can be safely managed overnight with an artificial pancreas.

February 4th

Potential New Class of AIDS Drugs Identified

Two compounds that act on novel binding sites for HIV protease--an enzyme critical to the life cycle of the virus that causes AIDS--have been identified by researchers at the Scripps Research Institute and collaborating institutions, including Pfizer and GlaxoSmithKline. The discovery lays the foundation for the development of a new class of anti-HIV drugs to enhance existing therapies, treat drug-resistant strains of the disease, and slow the evolution of drug resistance in the virus. Drugs that block the HIV protease already exist and currently make up an important part of the successful AIDS drug cocktail known as highly active anti-retroviral therapy (HAART). Compared with the nine U.S. Food and Drug Administration (FDA)-approved drugs that target HIV protease, however, the two new compounds, which are small chemical units or "fragments," bind with two novel parts of the molecule. This could make future drugs incorporating the fragments' novel structural elements a useful complement to existing treatments. "The study's results open the door to a whole new approach to drug design against HIV protease," said Scripps Research Associate Professor C. David Stout, senior author of the study. "The fragments bound at not one, but two, different crevices in protease outside the active site. This is an important proof-of-concept that the protease molecule has two non-active site binding pockets (allosteric sites) which can now be exploited as a powerful new strategy to combat drug-resistance in HIV." The article describing this work is currently available online and will be featured as the cover story of the March issue of Chemical Biology & Drug Design. [Press release]