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January 28, 2009, 6:13 AM CT

How memories change in the brain over time

How memories change in the brain over time
A new brain imaging study illustrates what happens to memories as time goes by. The study, in the January 28 issue of The Journal of Neuroscience, shows that distinct brain structures are involved in recalling recent and older events.

The findings support earlier studies of memory-impaired patients with damage limited to the hippocampus. These patients show deficits in learning new information and in recalling events that occurred just previous to their injuries. However, they are able to recall older events, which are thought to involve other regions of the brain, especially the cortex.

"It has long been known that older memories are more resistant to hippocampal damage than newer memories, and this was thought to reflect the fact that the hippocampus becomes less involved in remembering as a memory gets older," said Russell Poldrack, PhD, an expert on the cognitive and neural mechanisms of memory at the University of California, Los Angeles, who was not involved in the study. "However, there has been a recent debate over whether the hippocampus ever really stops being involved, even for older memories," Poldrack said.

To address this debate, Christine Smith, PhD, and Larry Squire, PhD, at the University of California, San Diego and the San Diego VA Medical Center, imaged study participants as they answered 160 questions about news events that occurred over the past 30 years. The hippocampus and related brain structures were most active when recalling recent events. Hippocampal activity gradually declined as participants recalled events that were 1-12 years old and remained low when they recalled events that were 13-30 years old.........

Posted by: Daniel      Read more         Source


January 26, 2009, 11:37 PM CT

Statins may treat blood vessel disorder

Statins may treat blood vessel disorder
In a finding that could save thousands of lives a year, University of Utah School of Medicine scientists have shown that a blood vessel disorder leading to unpredictable, sometimes fatal, hemorrhagic strokes, seizures, paralysis or other problems is treatable with the same statin drugs that millions of people take to control high cholesterol.

If the results of a study in mice are confirmed in a pilot trial with people, statins could provide a safe, inexpensive therapy for cerebral cavernous malformation (CCM), a disorder with no known drug treatment, as per U of U heart specialist Dean Y. Li, M.D., Ph.D., director of the Molecular Medicine Program and corresponding author of a study published Jan. 18 in Nature Medicine online.

"Brain surgery or radiation therapy has been the only option for CCM patients. But because of the risks in those operations, neurosurgeons are reluctant to perform them unless the patient is in immediate danger," Li said. "Our study proposes a potential strategy for a simple drug treatment that could cost only a few dollars a month at a pharmacy. However, our animal studies must first be reviewed in a pilot clinical trial being initiated".

Kevin J. Whitehead, M.D., also a heart specialist, assistant professor of internal medicine, and first author of the study, now is recruiting 50 to 100 people diagnosed with CCM to join a pilot trial of statins.........

Posted by: Daniel      Read more         Source


January 26, 2009, 11:32 PM CT

Gene therapy for rheumatoid arthritis

Gene therapy for rheumatoid arthritis
Scientists have reported the first clinical evidence that gene treatment reduces symptoms in patients with rheumatoid arthritis, an important milestone for this promising therapy which has endured a sometimes turbulent past. Described in the recent issue of the journal Human Gene Therapy the findings stem from a study of two patients with severe rheumatoid arthritis conducted in Gera number of and led by an investigator at Beth Israel Deaconess Medical Center (BIDMC).

Originally conceived as a means of treating genetic diseases, such as cystic fibrosis and hemophilia, gene treatment involves implanting a normal gene to compensate for a defective gene in the patient. The first clinical trial to test gene treatment was launched in 1990 for the therapy of a rare, genetic immunodeficiency disease.

"This study helps extend gene treatment research to nongenetic, nonlethal diseases," explains principal investigator Christopher Evans, PhD, Director of the Center for Advanced Orthopaedic Studies at BIDMC. "Rheumatoid arthritis [RA] is an extremely painful condition affecting multiple joints throughout the body. Arthritis is a good target for this therapy because the joint is a closed space into which we can inject genes," adds Evans, who is also the Maurice Muller Professor of Orthopaedic Surgery at Harvard Medical School.........

Posted by: Mark      Read more         Source


January 26, 2009, 6:21 AM CT

Brain's memory 'buffer' in single cells

Brain's memory 'buffer' in single cells
Dr. Don Cooper and colleagues have reported that individual nerve cells in the front part of the brain can hold traces of memories on their own for as long as a minute and possibly longer. The finding has implications for addiction, attention disorders and stress-related memory loss.

Credit: UT Southwestern Medical Center
Individual nerve cells in the front part of the brain can hold traces of memories on their own for as long as a minute and possibly longer, scientists at UT Southwestern Medical Center have found.

The study, available online and appearing in the recent issue of Nature Neuroscience, is the first to identify the specific signal that establishes nonpermanent cellular memory and reveals how the brain holds temporary information. It has implications for addiction, attention disorders and stress-related memory loss, said Dr. Don Cooper, assistant professor of psychiatry at UT Southwestern and senior author of the study conducted in mice.

Scientists have known that permanent memories are stored when the excitatory amino acid glutamate activates ion channels on nerve cells in the brain to reorganize and strengthen the cells' connections with one another. But this process takes minutes to hours to turn on and off and is too slow to buffer, or temporarily hold, rapidly incoming information.

The scientists observed that rapid-fire inputs less than a second long initiate a cellular memory process in single cells lasting as long as minute, a process called metabotropic glutamate transmission. This transmission in the most highly evolved brain region holds moment-to-moment information.........

Posted by: Daniel      Read more         Source


January 20, 2009, 7:28 PM CT

Is genetic theory of inheritance incorrect?

Is genetic theory of inheritance incorrect?
Scientists at the Centre for Addiction and Mental Health (CAMH) have detected evidence that DNA may not be the only carrier of heritable information; a secondary molecular mechanism called epigenetics may also account for some inherited traits and diseases. These findings challenge the fundamental principles of genetics and inheritance, and potentially provide a new insight into the primary causes of human diseases.

Your mother's eyes, your father's height, your predisposition to disease-- these are traits inherited from your parents. Traditionally, 'heritability' is estimated by comparing monozygotic (genetically identical) twins to dizygotic (genetically different) twins. A trait or disease is called heritable if monozygotic twins are more similar to each other than dizygotic twins. In molecular terms, heritability has traditionally been attributed to variations in the DNA sequence.

CAMH's Dr. Art Petronis, head of the Krembil Family Epigenetics Laboratory, and his team conducted a comprehensive epigenetic analysis of 100 sets of monozygotic and dizygotic twins in the first study of its kind. Said Dr. Petronis, "We investigated molecules that attach to DNA and regulate various gene activities. These DNA modifications are called epigenetic factors."

The CAMH study showed that epigenetic factors acting independently from DNA were more similar in monozygotic twins than dizygotic twins. This finding suggests that there is a secondary molecular mechanism of heredity. The epigenetic heritability may help explain currently unclear issues in human disease, such as the presence of a disease in only one monozygotic twin, the different susceptibility of males (e.g. to autism) and females (e.g. to lupus), significant fluctuations in the course of a disease (e.g. bipolar disorder, inflammatory bowel disease, multiple sclerosis), among numerous others.........

Posted by: Scott      Read more         Source


January 20, 2009, 6:14 AM CT

Turning those tumor suppressor genes on

Turning those tumor suppressor genes on
Scientists at Mayo Clinic have observed that the experimental drug they are testing to treat a deadly form of thyroid cancer turns on a powerful tumor suppressor capable of halting cell growth. Few other cancer drugs have this property, they say.

In the Feb. 15 issue of Cancer Research (available online Jan. 20), they report that RS5444, being tested in a Phase 1/2 clinical trial to treat anaplastic thyroid cancer, might be useful for treating other cancers. The agent is also known as CS-7017.

From prior research, the researchers knew that RS5444 binds to a protein known as PPAR-gamma, a transcriptional factor that increases the expression of a number of genes. They had observed that human anaplastic thyroid tumor cells treated with RS5444 expressed a protein known as p21, which inhibited cell replication and tumor growth. But they did not understand how. They have now discovered that the agent actually forces PPAR-gamma to turn on the RhoB tumor suppressor gene, which in turn induces p21 expression.

"This is very unusual," says the study's lead investigator, John Copland, Ph.D., a cancer biologist at the Mayo Clinic campus at Jacksonville. "Drugs typically target genes and proteins that are over-expressed and turn them off. We observed that RS5444 turns on a valuable tumor suppressor gene. We rarely find a drug that can take a suppressed gene and cause it to be re-expressed."........

Posted by: Janet      Read more         Source


January 19, 2009, 6:18 AM CT

Does water pollution cause male infertility?

Does water pollution cause male infertility?
New research strengthens the link between water pollution and rising male fertility problems. The study, by Brunel University, the Universities of Exeter and Reading and the Centre for Ecology & Hydrology, shows for the first time how a group of testosterone-blocking chemicals is finding its way into UK rivers, affecting wildlife and potentially humans. The research was supported by the Natural Environment Research Council and is now reported in the journal Environmental Health Perspectives

The study identified a new group of chemicals that act as anti-androgens. This means that they inhibit the function of the male hormone, testosterone, reducing male fertility. Some of these are contained in medicines, including cancer therapys, pharmaceutical therapys, and pesticides used in agriculture. The research suggests that when they get into the water system, these chemicals may play a pivotal role in causing feminising effects in male fish.

Earlier research by Brunel University and the University of Exeter has shown how female sex hormones (estrogens), and chemicals that mimic estrogens, are leading to feminisation of male fish. Found in some industrial chemicals and the contraceptive pill, they enter rivers via sewage therapy works. This causes reproductive problems by reducing fish breeding capability and in some cases can lead to male fish changing sex.........

Posted by: Janet      Read more         Source


January 19, 2009, 6:13 AM CT

Progress in cancer treatment

Progress in cancer treatment
Dr. Andr Veillette, a researcher at the Institut de recherches cliniques de Montral (IRCM), and his team led by postdoctoral fellow Dr. Mario-Ernesto Cruz-Munoz, will publish in the upcoming issue of the prestigious journal Nature Immunology of Nature Publishing Group. This discovery could have a significant impact on the therapy of cancers and infectious diseases. Current therapys frequently achieve only limited results with these types of diseases, which affect hundreds of thousands of Canadians.

Dr. Veillette's team identified one of the basic mechanisms controlling NK ("natural killer") cell activity. Produced by the immune system, NK cells are responsible for recognizing and killing cancer cells and cells infected by viruses, such as viruses causing hepatitis and herpes. NK cell deficiency is linked to a higher occurence rate of cancers and serious infections. "Our breakthrough, comments Dr. Veillette, demonstrates that a molecule known as CRACC, which is present at the surface of NK cells, increases their killer function." Using mice, the scientists have shown that CRACC greatly improves the animals' ability to eliminate cancer cells such as melanoma (a skin cancer) and lymphoma (a blood cancer). Mice lacking the CRACC gene, generated in Dr. Veillette's laboratory, were found to be more susceptible to cancer persistence. On the other hand, stimulation of CRACC function was found to improve cancer cell elimination. Thus, stimulating CRACC could boost NK cell activity, helping to fight cancers. In addition, it could improve the ability to fight infections, which are also handled by NK cells.........

Posted by: Janet      Read more         Source


January 15, 2009, 7:16 PM CT

Genes and pancreatic cancer

Genes and pancreatic cancer
Abnormalities in genes that repair mistakes in DNA replication may help identify people who are at high risk of developing pancreas cancer, a research team from The University of Texas M. D. Anderson Cancer Center reports in the Jan. 15 issue of Clinical Cancer Research

Defects in these critical DNA repair genes may act alone or in combination with traditional risk factors known to increase an individual's likelihood of being diagnosed with this very aggressive type of cancer.

"We consider DNA repair to be the guardian of the genome," said main author Donghui Li, Ph.D., professor in the Department of Gastrointestinal Medical Oncology at M. D. Anderson. "If something is wrong with the guard, the genes are more readily attacked by tobacco carcinogens and other damaging agents".

With this in mind, Li and her colleagues set out to identify DNA repair genes that could act as susceptibility markers to predict pancreas cancer risk. In a case-control study of 734 patients with pancreas cancer and 780 healthy individuals, they examined nine variants of seven DNA repair genes. The repair genes under investigation were: LIG3, LIG4, OGG1, ATM, POLB, RAD54L and RECQL.

The scientists looked for direct effects of the gene variants (also called single nucleotide polymorphisms) on pancreas cancer risk as well as potential interactions between the gene variants and known risk factors for the disease, including family history of cancer, diabetes, heavy smoking, heavy alcohol consumption and being overweight.........

Posted by: Sue      Read more         Source


January 14, 2009, 11:34 PM CT

Alzheimer's research based on family consent

Alzheimer's research based on family consent
By the time they have been diagnosed with Alzheimer's disease, a number of patients' decision-making ability is so impaired that they cannot give informed consent to participate in research studies.

Close family members are left with the decision, but there is no clear policy for this so-called "surrogate" consent. Because of that, research about the increasingly common disease is often stalled.

But a newly released study led by the University of Michigan Health System suggests that older Americans are very supportive of family surrogate-based research, and would support having their family members enroll them in research in case of future incapacity. The study appears in the new issue of the journal Neurology.

Because of uncertainties about federal policy, some institutions have gone so far as to not allow surrogate consent at all and research has been halted at other institutions, says main author Scott Y. H. Kim, M.D., Ph.D., associate professor in the U-M Medical School's Department of Psychiatry; investigator in the U-M Center for Behavioral and Decision Sciences in Medicine; and core member of the U-M Bioethics Program.

The federal policy states that surrogate consent can be provided by legally authorized representatives of adult patients, but the federal government defers to states to define who these representatives are. The lack of a clear definition has caused widespread confusion and uncertainty for three decades, notes Kim.........

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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