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Archive - May 2009

Date

May 31st

Ancient Skeleton Reveals Signs of Leprosy in India in 2000 B.C.

Previously, the earliest widely accepted evidence for leprosy was in Asian texts dated 600 B.C. Now, scientific analysis of an ancient male skeleton has revealed signs of leprosy infection and indicated that leprosy was present in India in 2000 B.C. The presence and patterning of lesions in the skeleton allowed a differential diagnosis for leprosy. These results represent the oldest documented skeletal evidence for the disease. Leprosy is a chronic infectious disease caused by Mycobacterium leprae that still today affects almost 250,000 people worldwide. The timing of first infection, the geographic origin, and the pattern of transmission of the disease are still under investigation. Comparative genomics research has suggested that M. leprae evolved either in East Africa or South Asia during the Late Pleistocene period before spreading to Europe and the rest of the World. The current work was published on May 27 in PLoS One. [PLoS One article]

Common Gene Variants Associated with Testicular Cancer

Testicular cancer is the most common cancer among young men between the ages of 15 and 40 and its incidence in non-Hispanic Caucasian men has doubled in the last 40 years. Researchers have now identified two common gene variants that are associated with increased susceptibility to this disease. This discovery lays the groundwork for genetic tests for susceptibility to testicular cancer which is over 90% curable if detected early. In a genome-wide association study, Dr. Katherine Nathanson, senior author of the report, and collaborators, found that men who have two copies of the common version of the c-KIT ligand (KITLG) gene have a 4.5-fold higher risk of testicular cancer than men who have two copies of the less common or minor version of the gene. Additionally, men with two copies of the common version of variants next to another gene, sprouty 4 (SPRY4), have a 1.48-fold higher risk than men with two copies of the less common version of this gene. "This finding is quite different than those observed in many other genome-wide association studies," Dr. Nathanson said. "In most studies, the increased risk of disease is associated with the less common variant of the gene. In this case, it is the more common variant in Caucasians that is associated with risk. If you carry two copies of the less common variant you are probably at incredibly low risk.” “Our observed strong association is intriguing and may reflect the impact of the genetic effect of KITLG," lead author Dr. Peter Kanetsky noted. "However, since the prevalence of the common variant is so high, it may also reflect other underlying factors required in conjunction with KITLG for disease development. This remains to be determined.” Additionally, the new findings may begin to explain why white men are more often diagnosed with testicular cancer than African American men.

May 30th

Blue-Light Goggles May Address Sleep Disturbances in Elderly

Scientists have created a blue-light-emitting goggle and shown that it may be effective in addressing fitfulness of sleep in the elderly. In recent years, scientists at Rensselaer Polytechnic Institute’s Lighting Research Center (LRC), and elsewhere, have demonstrated that blue light is the most effective at stimulating the circadian system, when combined with the appropriate light intensity, spatial distribution, timing, and duration. In the current work, a team at the LRC has tested a goggle-like device designed to deliver blue light directly to the eyes to improve sleep quality in older adults. “The study suggests that the light goggles might be a practical, comfortable, and effective way to deliver light treatment to those suffering from circadian sleep disorders. The next steps are to conduct field studies where we will be testing the effectiveness of this personal light-treatment device on those suffering from circadian-related sleep disorders, while also verifying the acceptance of the device among the test groups,” said Dr. Mariana Figueiro, the lead author of the study published in Chronobiology International. [Press release] [Chronobiology International abstract]

May 29th

Reason for Long, Prime-Numbered Life Cycles in Cicadas

Scientists may have discovered the reason for the long, prime-numbered life cycles (13 and 17 years) in periodical cicadas. A mathematical model used to predict the life cycles of these insects yielded these prime-numbered periods only when the so-called Allee effect was considered. This effect is a general model used to predict evolution that links large numbers of organisms to high survival rates. These results suggest that natural selection during times of low population size has favored the evolution of non-overlapping broods; broods emerging at the same time ultimately drive both populations to extinction. With 13- and 17-year life cycles, two neighboring broods of cicadas co-emerge approximately once every 221 years (13 times 17), greatly limiting the accompanying population crash. As cicadas depend on their overwhelming numbers to ward off predators, a smaller cicada population would result in increased mortality. This work was published online on May 18 in PNAS. [PNAS abstract]

May 28th

Mice with Human Speech Gene Show Suggestive Changes

Mice engineered to carry the humanized version of the FOXP2 gene show changes in brain circuits that have previously been linked to human speech, and the engineered mouse pups show qualitative differences in the ultrasonic vocalizations they use when placed outside the comfort of their mothers' nests. The FOXP2 gene has previously been putatively associated with development of speech in humans. One important difference between humans and chimpanzees are two amino acid substitutions in FOXP2. Those changes became fixed after the human lineage split from chimpanzees and earlier studies have yielded evidence that the gene underwent positive selection. That evolutionary change is thought to reflect selection for some important aspects of speech and language. "Currently, one can only speculate about the role these effects may have played during human evolution," the researchers wrote. "However, since patients that carry one nonfunctional FOXP2 allele show impairments in the timing and sequencing of orofacial movements, one possibility is that the amino acid substitutions in FOXP2 contributed to an increased fine-tuning of motor control necessary for articulation, i.e., the unique human capacity to learn and coordinate the muscle movements in lungs, larynx, tongue, and lips that are necessary for speech. We are confident that concerted studies of mice, humans, and other primates will eventually clarify if this is the case." The authors cautioned that not enough is known about mouse communication to yet read too much into what the current results might mean. The senior author of the report was Dr. Svante Paabo. The work was published in the May 29 issue of Cell.

May 27th

Dystrophin Substitute Shows Promise in Mouse Model of Muscular Dystrophy

Researchers have shown that use of a dystrophin-like molecule with a cell-penetrating tag can effectively repair weakened muscle in a mouse model of Duchenne muscular dystrophy (DMD). Muscular dystrophy causes the muscles in the body to progressively weaken. DMD is the most common and most severe form of childhood muscular dystrophy. About one of 3,500 boys is born with the crippling disease. Symptoms usually begin in children who are 2 to 3 years-old, most are in a wheelchair by age 12, and many who have the disease pass away by their late teens to early 20s. Current treatment, limited to corticosteroids, is minimally effective and can cause serious side effects. DMD is caused by mutation in the gene for the dystrophin protein, which is an important structural component within muscle tissue. In this work, the researchers used the dystrophin-like molecule utrophin, attached to a cell-penetrating tag called TAT. "This unique approach can replace the missing protein without the complexities of gene replacement or stem cell approaches," said Dr. James Ervasti, principal investigator of the study. This new method would not be a cure for muscular dystrophy. Rather, it would be a therapy most likely administered on a regular basis. Dr. Ervasti is hopeful that the therapy can move into human clinical trials within three years. This work was published in the May 26 edition of PLoS Medicine. [Press release] [PLoS Medicine article]

Hormone Addition May Solve Pod Shattering Problem in Oilseed Rape

Experiments in the related plant Arabidopsis suggest that artificial production of the hormone auxin in a specific region of the plant can prevent pod shattering and seed loss in brassica plants such as oilseed rape. Oilseed rape is grown for its tiny black oil-containing seeds, prized for cooking oil and margarines low in saturated fat, and increasingly for biodiesel. The meal that remains after oil extraction is also used as a high protein animal feed. Just before harvest, oilseed rape pods are prone to shatter, causing a 10-25% loss of seeds and up to 70% in some cases. Brassica plants normally disperse their seeds by a pod-shattering mechanism. Although this mechanism is an advantage in nature, it is one of the biggest problems in farming oilseed rape. As well as losing valuable seeds, it results in runaway 'volunteer' seedlings that contaminate the next crop in the rotation cycle. If rape seeds are harvested early to circumvent the problem, immature seeds may be collected which are of an inferior quality. This work is published in the May 28 issue of Nature. [Press release] [Nature abstract]

May 26th

Maturation Chemical May Fight Parasitic Worm Infections

A chemical that causes certain parasitic worms, including hookworms, to pass from the infective larval stage to the feeding larval stage may prove useful in reducing the risk posed by these worms throughout the world. The chemical is dafachronic acid and it sends the necessary signals for the worms to mature from the stage in which they infect a host to the stage in which they start feeding on the host, which is what makes the host sick. In this study, researchers treated hookworm parasites pharmacologically at the infective larval stage with dafachronic acid, causing them to pass into the feeding larval stage outside a host, where they had no food supply and died. Treatment of other infectious species had similar effects. Dr. David Mangelsdorf, the senior author of the study, said that the next step in the research is to screen large libraries of chemicals to search for compounds that behave like dafachronic acid and that could possibly be developed into pesticides that could be spread in high-infection areas. Many infectious nematode larvae live in the soil, often in areas where proper sanitation is lacking. According to the World Health Organization, parasitic nematodes infect about 2 billion people worldwide and severely sicken some 300 million, at least 50 percent of whom are school-age children. This report on dafachronic acid will be available online in PNAS and in an upcoming article in the journal. [Press release]

Folic Acid Consumption May Reduce Risk of Early Preterm Births

Folic acid consumption for a year or more before conception is associated with a 50%–70% decrease in early (but not late) spontaneous preterm births and the longer a woman takes folic acid supplements before becoming pregnant, the lower her risk of a preterm birth. These are the conclusions of researchers reporting recently in PLoS Medicine. The findings are particularly significant because premature babies (born before 37 weeks of completed pregnancy) are more likely to die than full-term babies and many have short- and/or long-term health problems. The severity of these health problems depends on the degree of prematurity—preterm babies born between 34 and 36 weeks of pregnancy rarely develop severe disabilities, but a quarter of babies born before 28 weeks of pregnancy develop serious lasting disabilities and half have learning and behavioral problems. The researchers noted the folic acid consumption itself may not be the causative factor as it may be a marker for a healthier lifestyle in general. Nevertheless, they said, the results suggest that long-term folic acid supplementation before conception is worth investigating further as a potential way to prevent preterm births. [PLoS Medicine article]

May 23rd

Specific Extra Phosphate on Tau Protein Crucial to Alzheimer’s Disease

Scientists have shown that a particular one of the multiple extra phosphates on the abnormal tau protein in Alzheimer’s disease appears to be a principal cause of the disease. "The impact of this study is twofold," said Dr. Hemant Paudel, the senior author of the study. "We can now do brain imaging at the earliest stages of the disease. We don't have to look for many different tau phosphates, just this single phosphate. The possibility of early diagnosis now exists. Second, the enzyme which puts this phosphate on the tau can be targeted by drugs, so therapies can be developed. This discovery gives us, for the first time, a clear direction towards the early diagnosis and treatment of Alzheimer's." Several years ago, it was discovered that tau proteins in normal brains contain only three to four attached phosphates, while abnormal tau proteins in Alzheimer's patients have anywhere from 21 to 25 additional phosphates. Here, Dr. Paudel and his team have shown that the addition of a single phosphate to the serine 202 amino acid within the tau protein is a likely principal culprit in Alzheimer's disease. This work was published in the May 15 issue of the Journal of Biological Chemistry. [Press release] [JBC abstract]