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May 6, 2008, 9:44 PM CT

Neurons duke it out for survival

Neurons duke it out for survival
The developing nervous system makes far more nerve cells than are needed to ensure target organs and tissues are properly connected to the nervous system. As nerves connect to target organs, they somehow compete with each other resulting in some living and some dying. Now, using a combination of computer modeling and molecular biology, neuroresearchers at Johns Hopkins have discovered how the target tissue helps newly connected peripheral nerve cells strengthen their connections and kill neighboring nerves. The study was reported in the April 18th issue of Science.

It was hard to imagine how this competition happens because the signal that leads cells to their targets also is responsible for keeping them alive, which begs the question: How do half of them die? says David Ginty, Ph.D., a professor of neuroscience and investigator of the Howard Hughes Medical Institute.

Target tissues innervated by so-called peripheral neurons coax nerves to grow toward them by releasing nerve growth factor protein, or NGF. Once the nerve reaches its target, NGF changes from a growth cue to a survival factor. In fact, when some populations of nerve cells are deprived of NGF they die. To further investigate how this NGF-dependent survival effect works the scientists looked for genes that are turned on by NGF in developing nerve cells.........

Posted by: Daniel      Read more         Source


May 5, 2008, 9:19 PM CT

Immune exhaustion in HIV infection

Immune exhaustion in HIV infection
Its the virus, stupid: immune exhaustion in HIV infection

As HIV disease progresses in a person infected with the HIV virus, a group of cells in the immune system, the CD8+ T lymphocytes, become exhausted, losing a number of of their abilities to kill other cells infected by the virus. For a number of years researchers have debated whether this exhaustion of CD8+ T cells is the cause, or the consequence, of persistence of the HIV virus. As per a research findings published this week in PLoS Medicine, Marcus Altfeld and his colleagues studied the immune response over time amongst 18 individuals who had very recently become infected with HIV.

These scientists observed that the presence of high amounts of HIV in the blood seemed to cause CD8+ T cell exhaustion; when antigen was reduced, either as a result of therapy with antiretroviral drugs, or evolution of viral epitopes to avoid recognition by CD8+ T cells, these epitope-specific CD8+ T cells recovered some of their original functions. These findings suggest that CD8+ T cell exhaustion is the consequence, rather than the cause, of persistent replication of HIV.

In a related article, Sarah Rowland-Jones and Thushan de Silva (from the Medical Research Council in Gambia), who were not involved in the study, discuss approaches to treat HIV efficiently by suppressing the viral load early in infection aimed at preserving HIV-1-specific immune function. They evaluate whether such strategies are likely to be practical.........

Posted by: Mark      Read more         Source


April 29, 2008, 8:11 PM CT

How cancer spreads

How cancer spreads
Metastasis, the spread of cancer throughout the body, can be explained by the fusion of a cancer cell with a white blood cell in the original tumor, as per Yale School of Medicine researchers, who say that this single event can set the stage for cancers migration to other parts of the body.

Their work was Reported in the recent issue of Nature Reviews Cancer. The studies, spanning 15 years, have revealed that the newly formed hybrid of the cancer cell and white blood cell adapts the white blood cells natural ability to migrate around the body, while going through the uncontrolled cell division of the original cancer cell. This causes a metastatic cell to emerge, which like a white blood cell, can migrate through tissue, enter the circulatory system and travel to other organs.

This is a unifying explanation for metastasis, said John Pawelek, a researcher in the Department of Dermatology at Yale School of Medicine and at Yale Cancer Center, who conducted the studies with colleague Ashok K. Chakraborty and several other Yale scientists. Eventhough we know a vast amount about cancer, how a cancer cell becomes metastatic still remains a mystery.

The fusion theory was first proposed in the early 1900s and has attracted a lot of scientific interest over the years. Pawelek and colleagues began their research several years ago by fusing white blood cells with tumor cells. These experimental hybrids the scientists observed, were remarkably metastatic and lethal when implanted into mice. In addition, the researchers noted, some of the molecules the hybrids used to metastasize originated from white blood cells, and these molecules were the same as those used by metastatic cells in human cancers. Pawelek and his team then validated prior findings that hybridization occurs naturally in mice, and results in metastatic cancer.........

Posted by: Janet      Read more         Source


April 28, 2008, 5:44 PM CT

Brain's Reaction to Potent Hallucinogen

Brain's Reaction to Potent Hallucinogen
Jacob Hooker
Brain-imaging studies performed in animals at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory provide scientists with clues about why an increasingly popular recreational drug that causes hallucinations and motor-function impairment in humans is abused. Using trace amounts of Salvia divinorum - also known as "salvia," a Mexican mint plant that can be smoked in the form of dried leaves or serum - Brookhaven researchers observed that the drug's behavior in the brains of primates mimics the extremely fast and brief "high" observed in humans. Their results are now published online in the journal NeuroImage.

Quickly gaining popularity among teenagers and young adults, salvia is legal in most states, but is grabbing the attention of municipal lawmakers. Numerous states have placed controls on salvia or salvinorin A - the plant's active component - and others, including New York, are considering restrictions.

"This is probably one of the most potent hallucinogens known," said Brookhaven chemist Jacob Hooker, the lead author of the study, which is the first to look at how the drug travels through the brain. "It's really important that we study drugs like salvia and how they affect the brain in order to understand why they are abused and to investigate their medicinal relevance, both of which can inform policy makers."........

Posted by: Daniel      Read more         Source


April 28, 2008, 5:11 PM CT

Stem Cells In the Pituitary

Stem Cells In the Pituitary
A team of scientists led by researchers at Cold Spring Harbor Laboratory have for the first time identified stem cells that allow the pituitary glands of mice to grow even after birth. They observed that, in contrast to most adult stem cells, these cells are distinct from those that fuel the initial growth of this important organ. The results suggest a novel way that the hormone-secreting gland may adapt, even in adolescents and adults, to traumatic stress or to normal life changes like pregnancy.

Seeking Adult Stem Cells

Maturity, in some respects, brings diminished possibilities. As a fertilized egg cell repeatedly divides to grow into a mature animal, most of the resulting cells become ever more specialized. But a small number of cells, known as stem cells, remain uncommitted even as they spawn more specialized progeny. The most versatile stem cells, taken from days-old embryos, are able to form any cell type - but studying them in people is controversial. Even in adults, however, other types of stem cell persist that have a more limited repertoire. Some replace specific cells as they wear out; others help to rebuild damaged tissues. Still other stem cells are suspected by some researchers of starting or maintaining cancers.

In spite of their importance, stem cells are hard to spot among the multitude of cells in complex tissue. Several years ago, neuroscientist Grigori Enikolopov, Ph.D., an associate professor at Cold Spring Harbor Laboratory (CSHL), and colleagues developed a tool to look for stem cells that give rise to new adult brain cells. Scientists had known that a gene called Nestin was active in these neural stem cells. The CSHL team genetically engineered mice so that the same conditions that activate Nestin in a particular cell also make it glow green under ultraviolet light.........

Posted by: Scott      Read more         Source


April 24, 2008, 10:09 PM CT

New technology for boosting vaccine efficiency

New technology for boosting vaccine efficiency
One of the most pressing biomedical issues is the development of techniques that increase the efficiency of vaccines. In a paper published on April 24, 2008 in the journal Vaccine, a Massachusettss biotechnology company, Cure Lab, Inc. has proposed a new technology for anti-viral vaccination. This technology consists of two major elements. First, each vaccine antigen should be made in two forms. One is easily processed within the organisms cells by an intracellular chopping machine called the proteosome, while another is resistant to the chopping. Thus both these forms of an antigen would be used in combination to elicit a much stronger immune response than either of them would be able to do alone.

Imagine a vaccine that could make a cell within our body produce a viral protein. This is called a recombinant vaccine. Recombinant vaccines give the most hope today as anti-viral and anti-cancer vaccines. They train the immune system to recognize and eliminate first infected or malignant cells, preventing a disease progression. In order for a recombinant vaccine to be effective, the produced viral protein must be presented by the cell to our immune system. This antigen presentation process is very complex and remains poorly understood.

A few years ago the situation seemed to be simple- said Dr. Alex Shneider, Founder and CEO of Cure Lab, Inc. - Vaccinologists believed that a recombinant vaccine makes the cell able to produce a viral protein. The proteosome cuts this protein into pieces. These pieces are then presented on the cell surface and stimulate immunity. If this was the complete story, life-saving solutions would be so close. A lot of research groups rushed to enhance their vaccines by fusing different viral proteins used in vaccines with specific transport signals directing the proteins to the proteosome. The logic was pretty straightforward. The more protein that would be targeted to a proteosome, the more protein segments generated for presentation to the immune system. This would then result in an elevated immune response.........

Posted by: Scott      Read more         Source


April 24, 2008, 5:11 AM CT

Heart derived stem cells develop into heart muscle

Heart derived stem cells develop into heart muscle
Dutch scientists at University Medical Center Utrecht and the Hubrecht Institute have succeeded in growing large numbers of stem cells from adult human hearts into new heart muscle cells. A breakthrough in stem cell research. Until now, it was necessary to use embryonic stem cells to make this happen. The findings appear in the latest issue of the journal Stem Cell Research.

The stem cells are derived from material left over from open-heart operations. Scientists at UMC Utrecht used a simple method to isolate the stem cells from this material and reproduce them in the laboratory, which they then allowed to develop. The cells grew into fully developed heart muscle cells that contract rhythmically, respond to electrical activity, and react to adrenaline.

Weve got complete control of this process, and thats unique, says principal investigator Prof. Pieter Doevendans. Were able to make heart muscle cells in unprecedented quantities, and on top of it theyre all the same. This is good news in terms of therapy, as well as for scientific research and testing of potentially new drugs.

Doevendans will use the cultured heart muscle cells to study things like cardiac arrhythmia (abnormal heart rhythms). Stem cells from the hearts of patients with genetic heart defects can be grown into heart muscle cells in the lab. Scientists can then study the cells responsible for the condition straight away. They can also be used to test new medicines. This could mean that research into genetic heart conditions can move forward at a much faster pace. In the future, new heart muscle cells can likely be used to repair heart tissue damaged during a heart attack.........

Posted by: Daniel      Read more         Source


April 21, 2008, 7:54 PM CT

Why teens get hooked on cocaine more easily

Why teens get hooked on cocaine more easily
New drug research suggests that teens may get addicted and relapse more easily than adults because developing brains are more powerfully motivated by drug-related cues. This conclusion has been reached by scientists who observed that adolescent rats given cocaine a powerfully addicting stimulant were more likely than adults to prefer the place where they got it. That learned association endured: Even after experimenters extinguished the drug-linked preference, a small reinstating dose of cocaine appeared to rekindle that preference but only in the adolescent rats.

The research, performed at McLean Hospital, Harvard Medical Schools largest psychiatric facility, was published in the recent issue of Behavioral Neuroscience, published by the American Psychological Association.

Evidence that younger brains get stuck on drug-related stimuli reinforces real-world data. Epidemiological studies confirm that of people in various age groups who experiment with drugs, teens are by far the most likely to become addicted. Thus, the new findings may be useful in developing new therapys for youthful addiction.

In the study, psychology experts Heather Brenhouse, PhD, and Susan Andersen, PhD, who directs McLeans Developmental Psychopharmacology Laboratory, introduced rats that were 38 or 77 days old (equivalent to 13 or 20 human years) to an apparatus with one central and two larger side chambers that had different flooring, wall colors and lighting. For three days in a row, the scientists injected the rats with saline solution in the morning and placed them in one side chamber for an hour. Four hours later, they injected them with a preference-forming dose of cocaine (either 10 or 20 mg per kg of weight, to assess two doses known to be habit-forming) and placed them in the opposite-side chamber for an hour. Conditioning this way kept the rats from associating the symptoms of withdrawal with the non-drug chamber.........

Posted by: JoAnn      Read more         Source


April 21, 2008, 6:34 PM CT

Brain reacts to fairness as it does to money and chocolate

Brain reacts to fairness as it does to money and chocolate
The human brain responds to being treated fairly the same way it responds to winning money and eating chocolate, UCLA researchers report. Being treated fairly turns on the brain's reward circuitry.

"We may be hard-wired to treat fairness as a reward," said co-author of study Matthew D. Lieberman, UCLA associate professor of psychology and a founder of social cognitive neuroscience.

"Receiving a fair offer activates the same brain circuitry as when we eat craved food, win money or see a beautiful face," said Golnaz Tabibnia, a postdoctoral scholar at the Semel Institute for Neuroscience and Human Behavior at UCLA and lead author of the study, which appears in the recent issue of the journal Psychological Science.

The activated brain regions include the ventral striatum and ventromedial prefrontal cortex. Humans share the ventral striatum with rats, mice and monkeys, Tabibnia said.

"Fairness is activating the same part of the brain that responds to food in rats," she said. This is consistent with the notion that being treated fairly satisfies a basic need, she added.

In the study, subjects were asked whether they would accept or decline another person's offer to divide money in a particular way. If they declined, neither they nor the person making the offer would receive anything. Some of the offers were fair, such as receiving $5 out of $10 or $12, while others were unfair, such as receiving $5 out of $23.........

Posted by: JoAnn      Read more         Source


April 17, 2008, 8:26 PM CT

Breakthrough in migraine genetics

Breakthrough in migraine genetics
Migraine is the most common cause of episodic headache, and by far the most common neurological cause of a doctors visit. It affects some 15% of the population, including some 41 million people in Europe, and places a considerable burden on healthcare in both the developed and the developing world.

During the last few years, great strides have been made in discovering common genes influencing the susceptibility to common diseases, such as diabetes, Crohns disease and schizophrenia. However, no genes have yet been convincingly linked to migraine susceptibility, probably due to the high degree of variability of the disease phenotype combined with the lack of viable laboratory tests.

To address this problem, we developed a new analysis technique concentrating on different symptoms of migraine, says Professor Aarno Palotie (University of Helsinki, Finland, and the Sanger Institute, Cambridge, UK). The new technique was used in the large international study including 1700 migraine patients and their close relatives from 210 Finnish and Australian migraine families. The Finnish families had been ascertained through neurology clinics, while the Australian families had been collected through a twin study. An initial genome-wide microsatellite study was followed up by an independent targeted replication study.........

Posted by: Daniel      Read more         Source



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Did you know?
Scientists at Yale have brought to light a mechanism that regulates the way an internal organelle, the Golgi apparatus, duplicates as cells prepare to divide, according to a report in Science Express.Graham Warren, professor of cell biology, and colleagues at Yale study Trypanosoma brucei, the parasite that causes Sleeping Sickness. Like a number of parasites, it is exceptionally streamlined and has only one of each internal organelle, making it ideal for studying processes of more complex organisms that have a number of copies in each cell.

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