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Archive - Mar 26, 2011

Research Sheds Light on Sense of Smell

Researchers seeking to unravel the most ancient yet least understood of the five senses – smell – have discovered a previously unknown step in how odors are detected and processed by the brain. The four-year study, focusing on how mice respond to odors, showed that smells are picked up by the olfactory bulb – the first stop on the way to the brain – then sent to the olfactory cortex for further analysis. But scientists discovered something else – a dialogue between the bulb and the cortex conducted by rapidly firing nerve cells. "It was originally thought that the olfactory bulb filtered and the olfactory cortex made decisions on whether something is, for example, edible," said lead researcher Dr. Diego Restrepo, professor of Cell and Developmental Biology and co-director of the University of Colorado School of Medicine Center for NeuroScience. "Our study says it's not quite like that. You process information on reward in the olfactory bulb, send it to the cortex and there is a dialogue between the two. Then the brain will act." The study was featured on the cover of the March 24, 2011 issue of Neuron. Dr. Restrepo, an expert on the science of taste and smell, said the discovery expands our understanding of how the olfactory system filters and categorizes the thousands of odors that bombard the brain daily. "We know very little about olfaction and we tend to think that it is not very important in humans compared to the other creatures," he said. "But much of what goes on is subtle and we are only beginning to understand it." For example, scientists recently found that when men sniffed the odorless tears of women, their levels of testosterone dropped. And for years it's been known that humans, like animals, secrete pheromones that may subconsciously help them choose a mate.

HIV Integration Requires Use of Host DNA-Repair Pathway

The human immunodeficiency virus (HIV), the cause of AIDS, makes use of the base excision repair pathway when inserting its DNA into the host-cell genome, according to a new study led by researchers at the Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute. Crippling the repair pathway prevents the virus from completing this critical step in the retrovirus's life cycle. The findings offer potential new targets for novel anti-HIV drugs that may not lead as quickly to viral resistance as current drugs, the researchers say. "HIV continues to develop resistance to current therapies," says first author Dr. Kristine Yoder, assistant professor of molecular virology, immunology, and medical genetics. "But the proteins we talk about in this paper are made by the cell, so drugs that target them might not lead to resistance as quickly as drugs that target viral proteins. And while targeting host proteins does have the potential for side effects, studies of mice suggest that targeting some of these genes may not lead to significant side effects." The paper was published online on March 23, 2011, in the journal PLoS ONE. Cells normally use base excision repair to fix oxidative damage to DNA caused by reactive molecules such as hydrogen peroxide and oxygen radicals, which form during energy production and other metabolic processes. For this study, Dr. Yoder and her colleagues investigated the role of the repair pathway in the virus insertion process by engineering four strains of mouse fibroblast cells that each lacked a component of the pathway. Specifically, they deleted genes for three glycosylase enzymes – Ogg1, Myh, and Neil1 – and one polymerase gene, Pol-beta.

Neural-Like Stem Cells Found in Pig Blood

A group of scientists at Marshall University in West Virginia is conducting research that may someday lead to new treatments for repair of the central nervous system. Dr. Elmer M. Price, who heads the research team and is chairman of Marshall’s Department of Biological Sciences, said his group has identified and analyzed unique adult animal stem cells that can turn into neurons. Dr. Price said the neurons they found appear to have many of the qualities desired for cells being used in development of therapies for slowly progressing, degenerative conditions like Parkinson’s disease, Huntington’s disease and multiple sclerosis, and for damage due to stroke or spinal cord injury. According to Dr. Price, what makes the discovery especially interesting is that the source of these neural stem cells is adult blood, a readily available and safe source. Unlike embryonic stem cells, which have a tendency to cause cancer when transplanted for therapy, adult stems like those identified in Dr. Price’s lab are found in the bodies of all living animals and do not appear to be carcinogenic. “Neural stem cells are usually found in specific regions of the brain, but our observation of neural-like stem cells in blood raises the potential that this may prove to be a source of cells for therapies aimed at neurological disorders,” Dr. Price added. So far, the group at Marshall has been able to isolate the unique neural cells from pig blood. Price said pigs are often used as models of human diseases due to their anatomical and physiological similarities to humans. In the future, his lab will work to isolate similar cells from human blood, paving the way for patients to perhaps one day be treated with stem cells derived from their own blood.