19 November 2008

Biomedicine News

Alexey Levin, Voice of America

Teeth and nerves
Stem cells of soft dental tissue contribute to the emergence of new brain neuronsEmployees of the American National Yerkes Center for Primatological Research, associated with Emory University in Atlanta, have discovered a way to renew nerve cells in the brain.

As the results of experiments on primates have shown, this effect can be achieved with the help of dental pulp stem cell transplantation. This is the name of the loose connective tissue of the central part of the tooth, which contains nerve endings and small blood vessels in abundance. There are also many specialized stem cells in the pulp, which not only renew the stock of its own cells, but also give rise to hard dental tissue, dentin. Although their concentration is especially high in baby teeth, they are also present in the dental pulp of adults.

Anthony Chan and his assistants isolated stem cells from the dental pulp of adult rhesus monkeys and planted them in the brains of mice. They chose the hippocampus, the part of the brain that is responsible for the formation of long-term memory, as the transplantation zone. After this procedure, new cells appeared in the hippocampus, many of which developed into full-fledged neurons.

This result is of interest not only for fundamental biology. When a person develops Alzheimer's disease, it first causes the death of hippocampal neurons, and then affects the cerebral cortex. It is possible that the progress of this terrible disease will be slowed down by transplanting stem cells isolated from the pulp of the patient himself into the hippocampus. In any case, Dr. Chen believes that this technique should be tested in subsequent experiments.

It is worth noting that the possibility of using pulp stem cells to combat neurodegenerative diseases was realized several years ago. Cells of this type were first isolated in 2000. 4 years later, researchers at the University of Michigan published the results of experiments that gave reason to hope that these cells could become a weapon against Parkinson's disease. New experiments by scientists from Atlanta confirm these hopes.

Aging without neurofibrils
The peculiarity of the brain tissues of people who are completely immune to senile memory loss has been revealedFortunately for humanity, mental abilities do not necessarily weaken in old age.

There are many centenarians who are 80, 90 years old, and even 100 years old, are distinguished by a sharp mind and excellent memory. Researchers from Northwestern University of Chicago decided to see if there were any specific features in the brain tissues of such lucky people that could be associated with the long-term preservation of their mental abilities.

To answer this question, Professor of neurology Changiz Geula and his colleagues conducted a detailed postmortem analysis of brain tissue slices of five people who, during their ninth decade, showed excellent results in memory and intelligence tests. They presented their findings on November 16 in Washington at the 38th annual conference of the Society for Neurological Research.

Almost all elderly people have deposits of beta-amyloid peptides in the brain tissues, which accumulate on the surface of nerve cells. At the same time, microscopic glomeruli of tangled strands of insoluble tau protein (such strands are called neurofibrils) appear inside these cells. When the number of neurons containing beta-amyloid coatings and neurofibrillary inclusions crosses some boundary, a person begins to develop Alzheimer's disease. However, such structures are a thousand times less present in the brains of people who do not show any symptoms of this disease.

The study of these age-related changes in brain tissue just made it possible to notice the difference that the Chicago scientists wanted to find. The number of beta-amyloid plaques in five centenarians with fully preserved intelligence was about the same as in their peers, who still had moderate forgetfulness during their lifetime, quite common for very elderly people. However, the number of neurofibrillary glomeruli inside the neurons of the brain was noticeably less than the typical age norm.

Of course, so far it cannot be ruled out that scientists just stumbled upon a random fluctuation, because the five is a small number. Now these conclusions first of all have to be verified, and if confirmed, explain. It's not worth guessing further yet.

Anti-RNA to protect the heart
Scientists from Colorado have successfully tested an experimental drug on mice that prevents the development of heart failureHeart failure is one of the most common and very severe cardiac disorders.

With this disease, the heart muscle stops pumping blood in a normal mode, which leads to the development of severe pathological processes affecting the lungs, liver and other organs. Heart failure most often occurs as a consequence of coronary thrombosis, congenital heart valve defects, arrhythmia and severe hypertension. According to medical statistics, more than 20 million people of different ages suffer from this disease worldwide.

Last year, researchers at the University of Texas found that the accumulation of very short miR-208 ribonucleic acid molecules in the blood, consisting of only 22 nucleotides, contributes to the development of heart failure. They appear during the copying of genetic information recorded on one of the "empty" fragments of the gene involved in the production of the muscle protein alpha-myosin.

Such fragments, the so-called introns, do not contain information about the structure of proteins and are therefore cut out when editing RNA chains synthesized during gene transcription. However, micro-RNA molecules play an important role in many biochemical processes unfolding inside cells.

Employees of the biotech firm Miragen Therapeutics, established last year, located in Boulder, Colorado, have found a way to neutralize miR-208 molecules. To do this, they synthesized other RNA chains capable of connecting with miR-208 and depriving them of the ability to participate in biochemical reactions. A drug containing antagonist molecules was injected into mice with artificially blocked venous blood outflow. Such therapy prevented the development of heart failure, which in these conditions inevitably occurred in untreated mice from the control group.

Scientists from Boulder intend to repeat these experiments on larger animals, most likely pigs or sheep. If the results do not disappoint their expectations, it will be possible to think about clinical trials of the new method.

Portal "Eternal youth" www.vechnayamolodost.ru19.11.2008

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