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Archive - 2014

January 6th

10-Year Study Shows Keys to Successful Long-Term Weight Loss Maintenance

Researchers from The Miriam Hospital in Providence, Rhode Island, together with collaborators, have published one of the first studies of its kind to follow weight loss maintenance for individuals over a 10-year period. The results show that long-term weight loss maintenance is possible if individuals adhere to key health behaviors. The study is published in the January 2014 issue of the American Journal of Preventive Medicine. J. Graham Thomas, Ph.D., is the lead author on a 10-year observational study of self-reported weight loss and behavior change in nearly 3,000 participants. The participants had lost at least 30 pounds and had kept if off for at least one year when they were enrolled in the National Weight Control Registry (NWCR).vThe participants were then followed for 10 years. Dr. Thomas explains that the goal of the study was to determine how well they kept the weight off and to identify predictors of successful weight loss maintenance. Dr. Thomas says, "On average, participants maintained the majority of their weight loss over this extended follow-up period, and better success was related to continued performance of physical activity, self-weighing, low-fat diets, and avoiding overeating." Other findings from the study show that more than 87 percent of the participants were estimated to be still maintaining at least a 10 percent weight loss at years five and 10. The researchers found that a larger initial weight loss and longer duration of maintenance were associated with better long-term outcomes. Conversely, they found that decreases in physical activity, dietary restraint and self-weighing along with increases in fat intake were associated with greater weight regain. Dr. Thomas concludes, "This is one of the only studies to follow weight loss maintenance over such a long term.

January 3rd

Mating Observed for First Time in Sleeping Sickness Parasites

Caught in the act! Researchers from the University of Bristol in the UK have observed mating for the first time in the microbes responsible for African sleeping sickness. This tropical disease is caused by trypanosomes, single-celled parasites that are found in the blood of those afflicted. The Bristol team was able to see what the trypanosomes were doing inside the tsetse flies that carry the disease by using fluorescent markers. The microscopic parasites were seen twirling and gyrating together before joining up into one hybrid cell. To tell which was which, individual trypanosomes were tagged with different colors, with the result that the hybrid cells had both colours. Professor Wendy Gibson, who led the research, commented: “It’s not only bigger animals that have intricate courtship – but you need a powerful microscope to see this!” Sex matters for microbes because it enables genes to be swapped between different strains, leading to new combinations of genes. In the case of disease-causing microbes like the trypanosome, sex can potentially lead to a lot of harmful genes being combined in one strain. These new results suggest that sex is not an optional or rare part of this microbe’s life cycle, but probably happens every time two different trypanosomes find themselves together in the same tsetse fly. Trypanosomes (see image) belong to a strange group of protozoa that includes several other medically important parasites such as Leishmania, Trichomonas, and Giardia. In the past, all these microbes were thought to reproduce just by splitting in half, but now results show that they also use sex to swap genes between strains.

Loss of Function of Singe Gene Causes Type 2 Diabetes in Mice

Researchers from the University of Illinois at Chicago (UIC) College of Medicine have found that dysfunction in a single gene in mice causes fasting hyperglycemia, one of the major symptoms of type 2 diabetes. Their findings were reported online on December 30, 2013 in the journal Diabetes. If a gene called MADD (which codes for MAP kinase-activating death domain protein) is not functioning properly, insulin is not released into the bloodstream to regulate blood sugar levels, says Dr. Bellur S. Prabhakar, professor and head of microbiology and immunology at UIC and lead author of the paper. Type 2 diabetes affects roughly 8 percent of Americans and more than 366 million people worldwide. It can cause serious complications, including cardiovascular disease, kidney failure, loss of limbs and blindness. In a healthy person, beta cells in the pancreas secrete the hormone insulin in response to increases in blood glucose after eating. Insulin allows glucose to enter cells where it can be used as energy, keeping glucose levels in the blood within a narrow range. People with type 2 diabetes don’t produce enough insulin or are resistant to its effects. They must closely monitor their blood glucose throughout the day and, when medication fails, inject insulin. In previous work, Dr. Prabhakar isolated several genes from human beta cells, including MADD, which is also involved in certain cancers. Small genetic variations found among thousands of human subjects revealed that a mutation in MADD was strongly associated with type 2 diabetes in Europeans and Han Chinese. People with this mutation had high blood glucose and problems of insulin secretion – the “hallmarks of type 2 diabetes,” Dr. Prabhakar said.

January 3rd

Cleveland Clinic Researchers Create Online Colorectal Cancer Risk Calculator

Researchers at Cleveland Clinic have developed a new tool called CRC-PRO that allows physicians to quickly and accurately predict an individual's risk of colorectal cancer, as published in an open-access article in the January-February 2014 issue of the Journal of the American Board of Family Medicine. CRC-PRO, or Colorectal Cancer Predicted Risk Online, is designed to help both patients and physicians determine when screening for colorectal cancer is appropriate. Current guidelines recommend patients are screened at the age of 50. However, with this new tool, physicians will be better able to identify who is truly at risk and when screenings for patients are necessary. To develop the calculator, the researchers – led by Brian Wells, M.D., Ph.D., of the Department of Quantitative Health Sciences in Cleveland Clinic's Lerner Research Institute – analyzed data on over 180,000 patients from a longitudinal study conducted at the University of Hawaii. Patients were followed for up to 11.5 years to determine which factors were highly associated with the development of colorectal cancer. "Creating a risk calculator that includes multiple risk factors offers clinicians a means to more accurately predict risk than the simple age-based cutoffs currently used in clinical practice," said Dr. Wells. "Clinicians could decide to screen high-risk patients earlier than age 50, while delaying or foregoing screening in low-risk individuals." Dr. Wells and his colleagues hope that their new, user-friendly calculator will help improve the efficiency of colorectal cancer screenings. They also believe prediction tools like this can help lower healthcare costs by cutting down on unnecessary testing. The Multiethnic Cohort Study comprised a diverse ethnic population.

Deletion Increases Milk Production, Decreases Fertility in Dairy Cattle

Scientists have found a genomic deletion that affects fertility and milk yield in dairy cattle at the same time. The discovery can help explain a dilemma in dairy cattle breeding: the negative correlation between fertility and milk production. The work was published online on January 2, 2014 in the open-access journal PLOS GENETICS. For the past many years, milk yield in Scandinavian dairy cattle has gone in one clear direction: up. This has been due to targeted breeding programs and modern breeding methods. Despite putting large weight on the breeding goal in Nordic countries, almost no improvement is achieved for fertility. It now seems that this unfavourable correlation between milk yield and fertility is partially affected by a deletion of a simple gene sequence. The presence and effects of this mutation have recently been discovered by scientists from Aarhus University, the University of Liège, and MTT Agrifood Research Finland, in collaboration with the Danish Agricultural Advisory Service and the Nordic Cattle Genetic Evaluation. Scientists, farmers, and advisors have generally assumed that the reduction in fertility is primarily due to the negative energy balance of high-producing cows at the peak of their lactation, but now the scientists have also found a genetic explanation. “We have discovered a deletion encompassing four genes as the causative variant and shown that the deletion is a recessive embryonically lethal mutation,” explains Dr. Goutam Sahana. This means that the calves die while they are still embryos and are aborted or reported as insemination failure. The fact that the mutation is recessive means that both parents must carry it and pass the genes on to their calf for the calf to be affected.

Dogs Sense Small Variations in the Earth’s Magnetic Field

Researchers analyzed the body orientation of 70 dogs of different breeds, while the dogs relieved themselves in the open country and without being on the leash. The statistical analyses of the more than 7,000 observations (recorded together with the currently prevailing environmental conditions of the location, time of day, and other important parameters such as the familiarity of the terrain for each dog) was frustrating. In contrast to grazing cows, hunting foxes, and landing waterfowl (previous studies of the research collective), the dogs showed no clear preference for a particular body alignment while doing number one or number two. But then the researchers around Dr. Vlastimil Hart and Prof. Dr. Hynek Burda made a striking discovery. They sorted the collected data according to the small variations of the geomagnetic field during the period of data collection. These irregular, tiny changes in the intensity and declination of the magnetic field lines are recorded by magnetic observatories and freely accessible online. The emerging picture of the analysis of the categorized data is as clear as it is astounding: dogs prefer a body-alignment along the magnetic north-south axis, but only during periods of calm magnetic field conditions. After taking into account all other factors, the researchers concluded that with this discovery they provide clear indication of a magnetic sense in our four-legged friends. To many dog owners who know about the good navigation abilities of their protégés, the findings might not come as a surprise – but rather as an explanation for the "supernatural" abilities, although it is not clear to the researchers what the dogs might use their magnetic sense for.

Japanese Team Shows Jumping DNA in the Brain May Be a Cause of Schizophrenia

Stretches of DNA called retrotransposons, often dubbed “junk DNA,” might play an important role in schizophrenia. In a study published online on January 2, 2013 in the journal Neuron, a Japanese team revealed that LINE-1 retrotransposons are abnormally abundant in the schizophrenia brain, modify the expression of genes related to schizophrenia during brain development, and may be one of the causes of schizophrenia. Retrotransposons are short sequences of DNA that autonomously amplify and move around the genome. One class of retrotransposons named Long Interspersed Nuclear Elements (LINEs) make up a large part of the eukaryotic genome and it is believed that they may contribute to a number of disorders and diseases, such as cancer. LINE-1 retrotranspons have been shown to be more abundant in brain cells than in other cells in the body in adults, providing evidence for enhanced activity of LINE-1s in the human brain. However, the role played by LINE-1s in mental disorders, and in particular schizophrenia, has remained unclear. The team led by Dr. Kazuya Iwamoto from the University of Tokyo and Dr. Tadafumi Kato from the RIKEN Brain Science Institute demonstrated that the number of LINE-1 copies is elevated in the post-mortem brains of patients with schizophrenia. They show, using mouse and macaque models for schizophrenia and induced pluripotent stem (iPS) cells, that exposure to environmental risk factors during development, as well as the presence of genetic risk factors for schizophrenia, can lead to increased levels of LINE-1 copies in neurons. Employing whole genome analysis, the authors reveal that in schizophrenia patients LINE-1 reinserts into genes involved in synaptic function or schizophrenia and may result in disruptions in their normal functions.

Scientists Uncover Most Detailed Picture Yet of Muscular Dystrophy Defect, Then Design Targeted New Drug Candidates

Scientists from The Scripps Research Institute (TRSI) have revealed an atomic-level view of a genetic defect that causes a form of muscular dystrophy, myotonic dystrophy type 2, and have used this information to design drug candidates with potential to counter those defects—and reverse the disease. “This the first time the structure of the RNA defect that causes this disease has been determined,” said TSRI Associate Professor Matthew Disney, who led the study. “Based on these results, we designed compounds that, even in small amounts, significantly improve disease-associated defects in treated cells.” Myotonic dystrophy type 2 is a relatively rare form of muscular dystrophy that is somewhat milder than myotonic dystrophy type 1, the most common adult-onset form of the disease. Both types of myotonic dystrophy are inherited disorders that involve progressive muscle wasting and weakness, and both are caused by a type of genetic defect known as an “RNA repeat expansion,” a series of nucleotides repeated more times than normal in an individual’s genetic code. The repeat binds to the protein MBNL1, rendering it inactive and resulting in RNA splicing abnormalities—which lead to the disease. Many other researchers had tried to find the atomic-level structure of the myotonic dystrophy 2 repeat, but had run into technical difficulties. In a technique called X-ray crystallography, which is used to find detailed structural information, scientists manipulate a molecule so that a crystal forms. This crystal is then placed in a beam of X-rays, which diffract when they strike the atoms in the crystal. Based on the pattern of diffraction, scientists can then reconstruct the shape of the original molecule.

January 2nd

Pacific Plant Has Absorbed Six “Foreign” Genomes into Its Mitochondria

Amborella trichopoda, a sprawling shrub that grows on just a single island in the remote South Pacific, is the only plant in its family and genus. It is also one of the oldest flowering plants, having branched off from others about 200 million years ago. Now, researchers from Indiana University, with the U.S. Department of Energy Joint Genome Institute (DOE JGI), Penn State University, and the Institute of Research for Development in New Caledonia, have determined a remarkable expansion of the genome of the plant's critical energy-generating structures. Its mitochondria, the plant's energy-producing organelles, in an epic demonstration of horizontal gene transfer, have acquired six genome equivalents of foreign DNA -- one from a moss, three from green algae, and two from other flowering plants. It is the first time that an organelle has captured entire "foreign" genomes, those from other organisms, and the first description of a land plant acquiring genes from green algae. "It swallowed whole genomes from other plants and algae as well as retained them in remarkably whole forms for eons," said Indiana's Dr. Palmer, the senior author of the findings published December 20, 2013 in the journal Science. This work reports on the extent of Amborella's genomic gluttony. The work n the mitochondrial genome is accompanied by a report of the Amborella trichopooda nuclear genome by the Amborella Genome Project, the establishment of a high-quality Amborella trichopoda genome sequence by another group, and a Perspective piece linking the reports together. The DOE JGI Plant Program focuses on fundamental biology of photosynthesis, the conversion of solar to chemical energy, and the role of terrestrial plants and oceanic phytoplankton in global carbon cycling.

More Evidence Suggests Type 2 Diabetes Is an Inflammatory Disease

As people's waistlines increase, so does the incidence of type 2 diabetes. Now scientists have a better understanding of exactly what happens in the body that leads up to type 2 diabetes, and what likely causes some of the complications related to the disease. Specifically, scientists from Denmark have found that in mice, macrophages (see image of isolated macrophage), a specific type of immune cell, invade the diabetic pancreatic tissue during the early stages of the disease. Then, these inflammatory cells produce a large amount of pro-inflammatory proteins, called cytokines, which directly contribute to the elimination of insulin-producing beta cells in the pancreas, resulting in diabetes. This discovery was published in the January 2014 issue of the Journal of Leukocyte Biology. "The study may provide novel insights allowing development of tailor-made anti-inflammatory based therapies reducing the burden of type 2 patients," said Alexander Rosendahl, Ph.D., a researcher involved in the work from the Department of Diabetes Complication Biology at Novo Nordisk A/S, in Malov, Denmark. "These novel treatments may prove to complement existing therapies such as insulin and GLP-1 analogues." To make their discovery scientists compared obese mice that spontaneously developed diabetes to healthy mice. The mice were followed from a young age when the obese mice only showed early diabetes, to an age where they displayed systemic complication in multiple organs. Presence of macrophages around the beta cells in the pancreas and in the spleen was evaluated by state-of-the-art flow cytometric technology allowing evaluation on a single cell level. At both the early and late stages, the diabetic mice showed significant modulations compared to healthy mice.