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Archive - Oct 4, 2014

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Genetic Test Indicates Risk of Atrial Fibrillation and Stroke

Many of those who are genetically predisposed to develop atrial fibrillation, which dramatically raises the risk of stroke, can be identified with a blood test. This has just been shown by new research from Lund University in Sweden. The number of people affected by atrial fibrillation is rising rapidly, partly as a result of the aging population. Over recent years, a research group at Lund University in Sweden, working with other universities and hospitals in Europe and the United States, has identified twelve genetic variants in the human genome that increase the risk of atrial fibrillation. The research group has now studied the possible clinical benefits of a DNA test: "One in five people has a genetic weakness that means they have twice as high a risk of developing atrial fibrillation as those with a low genetic risk. This genetic risk is therefore one of the strongest risk factors for atrial fibrillation that we know of in people without overt cardiac disease. It increases the risk as much as high blood pressure, for example," said Dr. Olle Melander, Professor of Internal Medicine, and Dr. Gustav Smith, Associate Professor in Cardiology, both from Lund University. Because the symptoms of atrial flutter can be weak and unclear, they are sometimes difficult to pick up. However, even those with weak or absent symptoms of atrial flutter are at significantly higher risk of stroke. "In patients who are suspected of having temporary, but recurrent, episodes of atrial fibrillation, or in people with high blood pressure, it can be important for doctors to look at their genetic predisposition using a blood test. The test can give guidance as to how often and how intensively doctors need to screen for presence of atrial fibrillation in these individuals.

Cattle Genome Variation Mapped in Unprecedented Detail

By creating a global database, an international consortium of scientists has increased the detailed knowledge of the variation in the cattle genome by several orders of magnitude. The first generation of the new data resource, which will be open access, forms an essential tool for scientists working with cattle genetics and livestock history. The results are published in as the cover story (image) of the August 2014 issue of Nature Genetics. It's momentous, says one of the scientists behind the international effort, associate professor Dr. Bernt Guldbrandtsen from the Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, Denmark. Scientists from Aarhus University – the only Danish university to participate – have been part of the consortium from the start and have contributed 15 percent of the data. The data used in the huge database are derived from key ancestor bulls. These bulls have produced millions of descendants and have had enormous influence on the genetic composition and characteristics of modern cattle breeds. For example, Holstein bulls in the database have fathered at least 6.3 million daughters worldwide. The data consist of sequenced genomes for a number of bulls and are based on new sequencing techniques. The article in Nature Genetics describes data from 232 bulls and 2 cows of the breeds Angus, Holstein, Jersey, and Fleckvieh. Because these animals are key ancestors, they carry most of the genetic variations present in the three races. Currently, the database contains genomes of more than 1,200 animals of different cattle breeds, but as more scientists from other countries gradually join the project, there is a continual influx of data.

Viral Infection in Utero May Trigger Type 1 Diabetes; Seasonality and Winter Epidemics Seem to Be Factors

The incidence of type 1 childhood diabetes has been increasing rapidly worldwide. If blood sugar levels aren't well-controlled, juvenile diabetes can affect nearly every organ of a child's body. And while long-term complications of the disease develop gradually, they may become disabling and even life-threatening. The exact cause of juvenile diabetes has eluded scientists, but a new study from Tel Aviv University (TAU) in Israel suggests a likely pre-birth trigge. In an article published in the June 2014 issue of Diabetic Medicine, Professor Zvi Laron, Professor Emeritus of Pediatric Endocrinology at TAU's Sackler Faculty of Medicine, Director of the Endocrinology and Diabetes Research Unit at Schneider Children's Medical Center of Israel, and Head of the WHO Collaborating Center for the Study of Diabetes in Youth, puts forth evidence that the autoimmune disease is initiated in utero. According to the research, conducted in collaboration with an international team of researchers, women who contract a viral infection during pregnancy transmit viruses to their genetically susceptible fetuses, sparking the development of type 1 diabetes. Professor Laron is internationally known for the discovery of the Laron Syndrome, also known as Laron-Type Dwarfism, an autosomal recessive disorder characterized by an insensitivity to growth hormone. "We knew that type 1 diabetes was associated with other autoimmune diseases like Hashimoto thyroiditis, celiac disease, and multiple sclerosis, so we investigated the seasonality of birth months for these respective diseases in Israel and other countries," said Professor Laron. "We found that the seasonality of the birth of children who went on to develop these diseases did indeed differ from that of the general public.

RCas9 Is a Programmable RNA Editing Tool, New Nature Article Says

A powerful scientific tool for editing the DNA instructions in a genome can now also be applied to RNA, the molecule that translates DNA’s genetic instructions into the production of proteins. A team of researchers with Berkeley Lab and the University of California (UC) Berkeley has demonstrated a means by which the CRISPR/Cas9 protein complex can be programmed to recognize and cleave RNA at sequence-specific target sites. This finding has the potential to transform the study of RNA function by paving the way for direct RNA transcript detection, analysis, and manipulation. Led by Dr. Jennifer Doudna (photo), biochemist and a leading authority on the CRISPR/Cas9 complex, the Berkeley team showed how the Cas9 enzyme can work with short DNA sequences known as “PAM,” for protospacer adjacent motif, to identify and bind with specific sites of single-stranded RNA (ssRNA). The team is designating this RNA-targeting CRISPR/Cas9 complex as RCas9. “Using specially designed PAM-presenting oligonucleotides, or PAMmers, RCas9 can be specifically directed to bind or cut RNA targets while avoiding corresponding DNA sequences, or it can be used to isolate specific endogenous messenger RNA from cells,” says Dr. Doudna, who holds joint appointments with Berkeley Lab’s Physical Biosciences Division and UC Berkeley’s Department of Molecular and Cell Biology and Department of Chemistry, and is also an investigator with the Howard Hughes Medical Institute (HHMI).

Review Questions Advisability of Aggressive Treatment with High Doses and Long Duration to Stem Emergence & Spread of Resistant Pathogens

In response to the rise of drug-resistant pathogens, doctors are routinely cautioned against overprescribing antimicrobials. But when a patient has a confirmed bacterial infection, the advice is to treat aggressively to quash the infection before the bacteria can develop resistance. A new study questions the accepted wisdom that aggressive treatment with high drug dosages and long durations is always the best way to stem the emergence and spread of resistant pathogens. The review of nearly 70 studies of antimicrobial resistance, which was authored by researchers at Princeton and other leading institutions, and published online in an open-access article on September 24, 2014 in the journal Proceedings of the Royal Society B, reveals the lack of evidence behind the practice of aggressive treatment in many cases. The article was entitled, “The Path of Least Resistance: Aggressive or Moderate Treatment?” "We found that while there are many studies that test for resistance emergence between different drug regimens, surprisingly few have looked at the topic of how varying drug dosage might affect the emergence and spread of resistance," said Ruthie Birger, a Princeton graduate student who works with Dr. C. Jessica Metcalf, an assistant professor of ecology and evolutionary biology and public affairs at Princeton's Woodrow Wilson School, and Dr. Bryan Grenfell, the Kathryn Briger and Sarah Fenton Professor of Ecology and Evolutionary Biology and Public Affairs in Princeton's Woodrow Wilson School. Birger, Drs. Metcalf and Grenfell coauthored the paper with colleagues from 16 universities. "We are a long way from having the evidence for the best treatment decisions with respect to resistance for a range of diseases," Dr. Birger said.