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Archive - Apr 27, 2017

Slender Face Identified As Novel Marker for Left-Handedness

Individuals with a slender lower face are about 25 percent more likely to be left-handed. This unexpected finding was identified in 13,536 individuals who participated in three national surveys conducted in the United States. This association may shed new light on the origins of left-handedness, as slender jaws have also been associated with susceptibility to tuberculosis, a disease that has shaped human evolution and which today affects 2 billion people. The finding was published on April 26, 2017 in the journal Laterality: Asymmetries of Body, Brain and Cognition. The article is titled “Handedness and Lower Face Variability: Findings in Three National Surveys.” The author, Philippe Hujoel, PhD, is a professor at the University of Washington School of Dentistry and an Adjunct Professor of Epidemiology at its School of Public Health. Slender jaws are a common facial feature, affecting about one in five U.S. adolescents. Past U.S. surveys measured the prevalence of this condition by evaluating how the upper and lower teeth come together. People with slender jaws typically have a lower jaw which bites a bit backward, giving them a convex facial profile and what's commonly called an overbite. "Almost 2,000 years ago a Greek physician was first to identify slender jaws as a marker for TB susceptibility, and he turned out to be right!" Dr. Hujoel said. "Twentieth-century studies confirmed his clinical observations, as slender facial features became recognized as one aspect of a slender physique of a TB-susceptible person.

Mouse Teeth Providing New Insights into Tissue Regeneration

Researchers hope to one day use stem cells to heal burns, patch damaged heart tissue, even grow kidneys and other transplantable organs from scratch. This dream edges closer to reality every year, but one of the enduring puzzles for stem cell researchers is how these remarkable cells know when it's time for them to expand in numbers and transform into mature, adult cells in order to renew injured or aging tissue. The answer to this crucial decision-making process may lie in a most remarkable organ: the front tooth of the mouse. Constantly growing incisors are the defining feature of all rodents, which rely on these sharp, chisel-like gnashers for burrowing and self-defense, as well as gnawing food. Inside the jaw, a mouse's incisors look more like a walrus's tusks or the teeth of a saber-toothed tiger, with only the sharpened tips showing through the gums at the front of the mouth. As the front of the tooth gets ground down, a pool of stem cells deep inside the jaw, at the very inner part of the tooth, is constantly building up the back of each incisor and pushing the growing tooth forward -- a bit like the lead of a mechanical pencil. "As we grow older, our teeth start to wear out, and in nature, once you don't have your teeth anymore, you die. As a result, mice and many other animals - from elephants to some primates - can grow their teeth continuously," said UC San Francisco's (UCSF’s) Ophir Klein, MD, PhD, a Professor of Orofacial Sciences in UCSF's School of Dentistry and of Pediatrics in the School of Medicine.

Variants in Five Genes Associated with Altitude Adaptation in Tibetans

The Tibetan people have inherited variants of five different genes that help them live at high altitudes, with one gene originating in the extinct human subspecies, the Denisovans. Dr. Hao Hu and Dr. Chad Huff of the University of Texas, Houston, and colleagues report these findings in a new study published online on April 27, 2017 in PLOS Genetics. The open-access article is titled “Evolutionary History of Tibetans Inferred from Whole-Genome Sequencing.” The people of Tibet have survived on an extremely high and arid plateau for thousands of years, due to their amazing natural ability to withstand low levels of oxygen, extreme cold, exposure to UV light, and very limited food sources. Researchers sequenced the whole genomes of 27 Tibetans and searched for advantageous genes. The analysis identified two genes already known to be involved in adaptation to high altitude, EPAS1 and EGLN1, as well as two genes related to low oxygen levels, PTGIS and KCTD12. They also picked out a variant of VDR, which plays a role in vitamin D metabolism and may help compensate for vitamin D deficiency, which commonly affects Tibetan nomads. The Tibetan variant of the EPAS1 gene originally came from the archaic Denisovan people, but the researchers found no other genes related to high altitude with Denisovan roots. Further analysis showed that Han Chinese and Tibetan subpopulations split as early as 44 to 58 thousand years ago, but that gene flow between the groups continued until approximately 9 thousand years ago. The study represents a comprehensive analysis of the demographic history of the Tibetan population and its adaptations to the challenges of living at high altitudes. The results also provide a rich genomic resource of the Tibetan population, which will aid future genetic studies. Co-author Dr.

Landmark Clinical Trial Supports Use of Drug Combination to Treat Eye Inflammation Associated with Juvenile Idiopathic Arthritis

A clinical trial funded by Arthritis Research UK and the National Institute for Health Research (NIHR) led by professors from the Universities of Liverpool and Bristol has discovered a drug combination that could help thousands of children with arthritis. Over 5,000 children and adolescents with Juvenile Idiopathic Arthritis (JIA) in the UK are likely to develop uveitis, a condition that causes inflammation in the middle layer of the eye. The drug combination discovery will help preventing them from serious complications, including blindness. The trial was the first of its kind in the world and the findings are a major step forward for children with JIA. The drug therapy has already been approved for use and the study is published today in The New England Journal of Medicine. The article is titled “Adalimumab Plus Methotrexate for Uveitis in Juvenile Idiopathic Arthritis.” The trial's Co-Chief Investigators, Professors Michael Beresford and A. V. Ramanan, and colleagues from across the UK, found that a drug called adalimumab, in combination with methotrexate, was an effective therapy in children and adolescents with JIA-associated uveitis. The majority (75 per cent) of those children treated with adalimumab experienced a significant reduction in eye inflammation. An early analysis of the data was so convincing that the trial was stopped early. In this randomized, placebo controlled trial on review of 90 of the target 149 patients with JIA-associated uveitis, the data and safety monitoring committee noted that the adalimumab group had evidence of a significantly lower risk of treatment failure than the placebo group.