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December 9, 2008, 9:25 PM CT

Genetic underpinnings of nicotine addiction

Genetic underpinnings of nicotine addiction
A new study from the Abramson Cancer Center and Department of Psychiatry in the University of Pennsylvania School of Medicine shows that smokers who carry a particular version of a gene for an enzyme that regulates dopamine in the brain may suffer from concentration problems and other cognitive deficits when abstaining from nicotine a problem that puts them at risk for relapse during attempts to quit smoking. The findings, newly reported in the journal Molecular Psychiatry, pave the way to identify novel medications to treat nicotine addiction.

"These findings also provide an important step toward personalized treatment for nicotine addiction by clarifying the role of inherited genetic variation in smoking abstinence symptoms that promote relapse," says senior author Caryn Lerman, PhD, the Mary W. Calkins Professor in Penn's Department of Psychiatry and Scientific Director of Penn's Abramson Cancer Center.

"The new data identify a novel brain-behavior mechanism that plays a role in nicotine dependence and relapse during quitting attempts," says lead author James Loughead, PhD, assistant professor in the Department of Psychiatry. Loughead and Lerman studied groups of smokers with different inherited variations in a gene which influences levels of dopamine in the prefrontal cortex, the part of the brain that governs working memory and complex decision-making. Spurred by their prior findings that carriers of the catechol-O-methyltransferase (COMT) val gene variant are more susceptible to smoking relapse, the Penn scientists set out to learn if smokers with this genetic background would be more likely to exhibit altered brain function and cognitive deficits during periods of abstinence from smoking.........

Posted by: Scott      Read more         Source


December 8, 2008, 10:14 PM CT

An Achilles heel in cancer cells

An Achilles heel in cancer cells
A protein that shields tumor cells from cell death and exerts resistance to chemotherapy has an Achilles heel, a vulnerability that can be exploited to target and kill the very tumor cells it commonly protects, scientists from the University of Illinois at Chicago show in a new study reported in the Dec. 9 issue of Cancer Cell

Akt is a signaling protein, called a kinase, that is hyperactive in the majority of human cancers.

"Akt is perhaps the most frequently activated oncoprotein (cancer-promoting protein) in human cancer," says Nissim Hay, professor of biochemistry and molecular genetics at the UIC College of Medicine. Pharmaceutical companies have been trying to find ways to inhibit Akt to improve cancer treatment, he said, but most candidate drugs have acted too broadly and proved toxic.

"One of Akt's major functions in tumor cells is promoting cell survival," Hay said. "Tumor cells with hyperactive Akt are not only resistant to the external stresses that can induce cell death but also to chemotherapy."

But Akt is also mandatory for metabolism and the proliferation of cancer cells, and it was as a byproduct of its role in metabolism that the scientists were able to exploit Akt hyperactivity against the tumor cell.

"We observed that cells with hyperactive Akt have increased intracellular levels of reactive oxygen species (ROS) and at the same time impaired ability to scavenge ROS," Hay said. These ROS are highly reactive byproducts of metabolism that can damage the cell. Cells commonly respond to high levels of ROS by undergoing cell suicide, or apoptosis.........

Posted by: Janet      Read more         Source


December 6, 2008, 4:12 PM CT

Insight on wonder of cell division

Insight on wonder of cell division
A photomicrograph made using fluorescent light microscopy shows a one-cell stage Caenorhabditis elegans (roundworm) embryo undergoing cell division. Microtubules (green) are rigid protein polymers that organize, capture and move chromosomes (blue) made up of DNA. Chromosomes are in two groups, which are being pulled by microtubules towards opposite poles of the bipolar spindle. The microfilament cytoskeleton (red) is at the cell cortex just underneath the cell membrane. These longer, more flexible protein polymers must be organized into a "cleavage furrow" that pulls a circumferential ring of the cell surface into the center of the cell, ultimately dividing the single parent cell into two daughter cells at the end of cell division -- each with one complete set of chromosomes and genes. The organization and constriction of the cleavage furrow happens slightly later.

Credit: Courtesy of Bruce Bowerman
Biologists have discovered a mechanism that is critical to cytokinesis -- nature's completion of mitosis, where a cell divides into two identical daughter cells.

The scientists have opened a new window on the assembly and activity of a ring of actin and myosin filaments that contract to pinch a cell at just the right time. They focused on key proteins whose roles drive signaling mechanisms that promote the production of both linear and branching microfilaments along the inside surface membrane of a dividing cell. By down-regulating the production of branched microfilaments at the right time, the membrane may be more malleable and better able to pinch inward and complete cytokinesis.

The findings-- detailed in the Dec. 5 issue of the journal Science -- come from basic research using Caenorhabditis elegans (roundworm) embryos. The discovery provides more basic insight than immediate biomedical application, but the implications could lead to a fine-tuning of anti-cancer drug therapies or to isolating new targets for drugs to stop malignant cell division, said Bruce Bowerman, professor of biology in the University of Oregon's Institute for Molecular Biology.

Bowerman and Karen Oegema of the Ludwig Institute for Cancer Research at the University of California, San Diego, were principal researchers of a seven-member team funded by the National Institutes of Health.........

Posted by: Scott      Read more         Source


December 6, 2008, 3:46 PM CT

Improving patient outcomes in several platelet disorders

Improving patient outcomes in several platelet disorders
Four studies that highlight significant advances in therapy and survival outcomes for patients with various forms of thrombocytopenia, a group of bleeding disorders characterized by a low number of platelets in the blood, will be presented in a press conference on Saturday, December 6, at 8:00 a.m., during the 50th Annual Meeting of the American Society of Hematology in San Francisco, CA. The studies featured in the press conference will report on a new combination treatment for previously untreated idiopathic thrombocytopenic purpura (ITP), an investigational oral therapy for chronic ITP, a low-dose platelet transfusion strategy for patients with hypoproliferative thrombocytopenia, and a new therapeutic platelet transfusion approach following high-dose chemotherapy and autologous stem cell transplantation.

"We have some very exciting data on novel therapeutic approaches to minimize bleeding episodes in patients with platelet disorders," said press conference moderator Kenneth Kaushansky, MD, 2008 President of the American Society of Hematology and Helen M. Ranney Professor and Chair of the Department of Medicine at the University of California, San Diego School of Medicine. "The results of these studies will likely transform the way hematologists treat and manage these conditions, ultimately resulting in improvements in overall patient outcomes such as reducing bruising and unnecessary bleeding that can result if left untreated."........

Posted by: Scott      Read more         Source


December 4, 2008, 7:44 PM CT

Gene packaging tells story of cancer development

Gene packaging tells story of cancer development
To decipher how cancer develops, Johns Hopkins Kimmel Cancer Center researchers say scientists must take a closer look at the packaging.

Specifically, their findings in the December 2, 2008, issue of PLoS Biology point to the three dimensional chromatin packaging around genes formed by tight, rosette-like loops of Polycomb group proteins (PcG). The chromatin packaging, a complex combination of DNA and proteins that compress DNA to fit inside cells, provides a repressive hub that keeps genes in a low expression state.

"We think the polycomb proteins combine with abnormal DNA methylation of genes to deactivate tumor suppressor genes and lock cancer cells in a primitive state," says Stephen B. Baylin, M.D., Virginia and D.K. Ludwig Professor of Oncology and senior author.

Previous to this discovery, researchers studying cancer genes, looked at gene silencing as a linear process across the DNA, as if genes were flat, one dimensional objects. Research did not take into account the way genes are packaged.

To better understand the role of the PcG packaging, the team compared embryonic cells to adult colon cancer cells. The gene studied in the embryonic cells was packaged by PcG proteins, in a low expression state, and had no DNA methylation. When the gene received signals for cells to mature, the PcG loops were disrupted and the gene was highly expressed. However, when the same gene was abnormally DNA methylated, as is the case in adult, mature colon cancer cells, the PcG packaging loops were tighter and there was no gene expression. "These tight loops touch and interact with a number of gene sites folding it into a structure that shuts off tumor suppressor genes," says Baylin. However, when the scientists removed DNA methylation from the cancer cells, the loops loosened somewhat, back to the state of an embryonic cell, and some gene expression was restored.........

Posted by: Scott      Read more         Source


December 3, 2008, 5:28 AM CT

Surgery to treat medication-resistant epilepsy

Surgery to treat medication-resistant epilepsy
Persons with temporal lobe epilepsy who do not respond to medicine could receive a substantial gain in life expectancy and quality of life by undergoing surgery of the temporal lobe part of the brain, as per an analysis published in the December 3 issue of JAMA.

Despite currently available anti-epileptic drugs, 20 percent to 40 percent of all patients with epilepsy do not respond to medical management. Temporal lobe epilepsy is the most common form of epilepsy and the most likely to be medically non-responsive, and these patients are at increased risk of premature death, as per background information in the article. An alternative form of therapy is temporal lobe resection (procedure in which brain tissue in the temporal lobe is cut away). Patients becoming seizure free after anterior (toward the front) temporal lobe resection have reduced death rates relative to patients continuing to have seizures.

"Studies have reported the effectiveness of temporal lobe resection since the 1950s, yet a minority of patients are being referred to surgery and those only after an average of 20 years of illness. For adolescents and young adults, this delay may be especially significant during a critical period in their psychosocial development," the authors write.

Hyunmi Choi, M.D., M.S., of the Columbia University Medical Center, New York, and his colleagues conducted an analysis using a simulation model to estimate the effect of anterior temporal lobe resection vs. continued medical management on life expectancy and quality-adjusted life expectancy among patients with medication-resistant temporal lobe epilepsy. The model incorporated possible surgical complications and seizure status and was populated with health-related quality-of-life data obtained directly from patients and data from the medical literature.........

Posted by: Daniel      Read more         Source


November 21, 2008, 8:19 PM CT

Better cancer diagnosis, drugs

Better cancer diagnosis, drugs
A Florida State University College of Medicine research team led by Yanchang Wang has discovered an important new layer of regulation in the cell division cycle, which could lead to a greater understanding of the way cancer begins.

Wang, an assistant professor of biomedical sciences at the College of Medicine, said the findings will lead to an improved ability to diagnose cancer and could lead to the design of new drugs that kill cancer cells by inhibiting cell reproduction. His paper on the discovery has been reported in the journal Proceedings of the National Academy of Sciences

"The correct timing of chromosome segregation during cell division is necessary to ensure normal, healthy growth," Wang said. "Now we have discovered a previously undetected layer of regulation in how the chromosomes separate, which helps to ensure the correct timing and decreases the potential for the formation of malignant growth".

The cell division cycle is a collection of tightly regulated events that lead to cell duplication. The most important events are the doubling of the hereditary information encoded within a set of chromosomes, and the division of that duplicated information into two daughter cells that are genetically identical to each other and the mother cell.........

Posted by: Janet      Read more         Source


November 18, 2008, 5:15 AM CT

Gene associated with epilepsy

Gene associated with epilepsy
A University of Iowa-led international research team has found a new gene linked to the brain disorder epilepsy. While the PRICKLE1 gene mutation was specific to a rare form of epilepsy, the study results could help lead to new ideas for overall epilepsy therapy.

The findings, which involved nearly two dozen institutions from six different countries, appear in the Nov. 7 issue of the American Journal of Human Genetics

In epilepsy, nerve cells in the brain signal abnormally and cause repeated seizures that can include strange sensations, severe muscle spasms and loss of consciousness. The seizures may not have lasting effects but can affect activities, such as limiting a person's ability to drive. Most seizures do not cause brain damage but some types of epilepsy lead to physical disabilities and cognitive problems. Medications can control symptoms, but there is no cure.

"The study results were surprising not only because the PRICKLE1 gene had never been linked to epilepsy but also because the gene was not linked to any other human disease," said the study's lead author Alex Bassuk, M.D., Ph.D., assistant professor of pediatrics at the University of Iowa Carver College of Medicine and a pediatric neurologist with University of Iowa Children's Hospital.........

Posted by: Daniel      Read more         Source


November 14, 2008, 8:20 PM CT

Tiny backpacks for cells

Tiny backpacks for cells
MIT researchers have developed a technique to attach tiny polymer "backpacks" to cells.
MIT engineers have outfitted cells with tiny "backpacks" that could allow them to deliver chemotherapy agents, diagnose tumors or become building blocks for tissue engineering.

Michael Rubner, director of MIT's Center for Materials Science and Engineering and senior author of a paper on the work that appeared online in Nano Letters on Nov. 5, said he believes this is the first time anyone has attached such a synthetic patch to a cell.

The polymer backpacks allow scientists to use cells to ferry tiny cargoes and manipulate their movements using magnetic fields. Since each patch covers only a small portion of the cell surface, it does not interfere with the cell's normal functions or prevent it from interacting with the external environment.

"The goal is to perturb the cell as little as possible," said Robert Cohen, the St. Laurent Professor of Chemical Engineering at MIT and an author of the paper.

The scientists worked with B and T cells, two types of immune cells that can home to various tissues in the body, including tumors, infection sites, and lymphoid tissues -- a trait that could be exploited to achieve targeted drug or vaccine delivery.

"The idea is that we use cells as vectors to carry materials to tumors, infection sites or other tissue sites," said Darrell Irvine, an author of the paper and associate professor of materials science and engineering and biological engineering.........

Posted by: Janet      Read more         Source


November 12, 2008, 10:37 PM CT

Hormone shows promise in reversing Alzheimer's disease

Hormone shows promise in reversing Alzheimer's disease
Saint Louis University scientists have identified a novel way of getting a potential therapy for Alzheimer's disease and stroke into the brain where it can do its work.

"We found a unique approach for delivering drugs to the brain," says William A. Banks, M.D., professor of geriatrics and pharmacological and physiological science at Saint Louis University. "We're turning off the guardian that's keeping the drugs out of the brain".

The brain is protected by the blood-brain barrier (BBB), a gate-keeping system of cells that lets in nutrients and keeps out foreign substances. The blood-brain barrier passes no judgment on which foreign substances are trying to get into the brain to treat diseases and which are trying to do harm, so it blocks them without discrimination.

"The problem in treating a lot of diseases of the central nervous system such as Alzheimer's disease, HIV and stroke is that we can't get drugs past the blood-brain barrier and into the brain," says Banks, who also is a staff doctor at Veterans Affairs Medical Center in St. Louis.

"Our new research shows a way of getting a promising therapy for these types of devastating diseases to where they need to be to work".

The treatment known as PACAP27 -- is a hormone produced by the body that is a general neuro-protectant. PACAP stands for pituitary adenylate cyclase-activating polypeptide. "It is a general protector of the brain against a number of types of insult and injury," Banks says.........

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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