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March 19, 2007, 9:38 PM CT
Cause of Smokers' Cravings
Video of Jed Rose explaining the regions of the brain that control craving is available in the following formats: RealMedia, QuickTime and Windows Media Video.
DURHAM, N.C. -- Within the mind of every smoker trying to quit rages a battle between the higher-order functions of the brain wanting to break the habit and the lower-order functions screaming for another cigarette, say scientists at Duke University Medical Center. More often than not, that cigarette gets lit.
Brain scans of smokers studied by the scientists revealed three specific regions deep within the brain that appear to control dependence on nicotine and craving for cigarettes. These regions play important roles in some of the key motivations for smoking: to calm down when stressed, to achieve pleasure and to help concentration.
"If you can't calm down, can't derive pleasure and can't control yourself or concentrate, then it will be extremely difficult for you to break the habit," said lead study investigator Jed E. Rose, Ph.D., director of the Duke Center for Nicotine and Smoking Cessation Research. "These brain regions may explain why most people try to quit several times before they are successful."
Understanding how the brain responds to cigarette cravings can help doctors change nicotine cessation therapys to address all three of these components of withdrawal, Rose said. Drugs or therapies that target these regions may help smokers stave off the cravings that often spoil their attempts to quit.........
Posted by: JoAnn Read more Source
March 19, 2007, 9:26 PM CT
Protein May Increase Chances of Pregnancy
In its early and most critical stages, human reproduction requires precise, vital functions. The role of one sperm-delivered protein, which is crucial to the process, is being closely observed by researchers from the United States and Canada. Lab tests in recent years have produced valuable information and hopes of regulating that protein to enhance fertility.
Peter Sutovsky, assistant professor of animal sciences in the University of Missouri-Columbia's College of Agriculture, Food and Natural Resources and assistant professor of clinical obstetrics and gynecology in the School of Medicine, has collaborated with Richard Oko, professor of anatomy and cell biology at Queen's University (Ontario), and other academic scientists examining the role of postacrosomal sheath WW domain binding protein (PAWP), which during fertilization must function properly to initiate the reproduction process. If not, reproduction won't occur, Sutovsky said.
PAWP's role is one of the earliest reproduction requirements, he said. The protein is located inside of the sperm head and separates from the sperm shortly after the sperm fuses with the egg cell. PAWP activates the fertilized egg to divide and become an embryo, and triggers a defense mechanism that stops additional sperm from penetrating the egg cell.........
Posted by: Emily Read more Source
March 14, 2007, 10:09 PM CT
This Drug Delivers Itself
The problem of efficiently delivering drugs, particularly those that are hydrophobic or water-repellant, to tumors or other disease sites has long challenged researchers to develop innovative delivery systems that keep these drugs intact until reaching their targets.
Now researchers in the University at Buffalo's Institute for Lasers, Photonics and Biophotonics and Roswell Park Cancer Institute have developed an innovative solution in which the delivery system is the drug itself.
They describe for the first time in Molecular Pharmaceutics a drug delivery system that consists of nanocrystals of a hydrophobic drug.
The system involves the use of nanocrystals measuring about 100 nanometers of pure HPPH, (2-devinyl-2-(1'-hexyloxyethyl) pyropheophorbide), a photosensitizer currently in Phase I/II human clinical trials at RPCI for treating various types of cancer.
The UB scientists observed that the nanocrystals of HPPH were taken up by tumors in vivo, with efficacy comparable to conventional, surfactant-based delivery systems.
A patent has been filed on this work.
"In this case, the drug itself acts as its own carrier," said Haridas Pudavar, Ph.D., UB research assistant professor of chemistry and a co-author.
The nanocrystals present a major advantage over methods of delivery involving other carriers, as per Paras Prasad, Ph.D., SUNY Distinguished Professor in the Department of Chemistry in UB's College of Arts and Sciences, executive director of the institute and a co-author.........
Posted by: Scott Read more Source
March 13, 2007, 10:20 PM CT
why we smell better when we sniff?
Cross section of olfactory sensory neurons in a mouse nose visualized by fluorescent staining.
Credit: Huikai Tian, PhD, Minghong Ma, PhD, University of Pennsylvania School of Medicine.
Unlike most of our sensory systems that detect only one type of stimuli, our sense of smell works double duty, detecting both chemical and mechanical stimuli to improve how we smell, as per University of Pennsylvania School of Medicine scientists in the recent issue of Nature Neuroscience.
This finding, plus the fact that both types of stimuli produce reaction in olfactory nerve cells, which control how our brain perceives what we smell, explains why we sniff to smell something, and why our sense of smell is synchronized with inhaling.
"The driving force for such synchronization remained a mystery for more than 50 years," says senior author Minghong Ma, PhD, Assistant Professor of Neuroscience. "These results help us understand how the mammalian olfactory system encodes and decodes odor information in the environment".
Scientists tested two different types of stimulation on olfactory neurons in mice: chemical stimuli, such as those used in making perfumes that have almond-like and banana-like scents, and mechanical stimuli, that is pressure carried by air flow to the nostrils while breathing.
The group did this first by puffing a chemical stimulus into the nose. As expected, this produced a reaction in the olfactory neurons, the primary sensory neurons in the nose that perceive odors. Scientists then puffed a solution without the chemical stimuli into the mouse's nose. This also produced a similar, but smaller reaction in the olfactory neurons. By decreasing pressure of the non-odor solution, they also observed that the reaction in the olfactory neurons was less, confirming that it was sensitive to mechanical stimulation.........
Posted by: Sue Read more Source
March 13, 2007, 9:22 PM CT
Vanishing Neurons Of Adolescence
Photo by L. Brian Stauffer
Psychology professor Janice Juraska, right, and graduate student Julie Markham
Scientists at the University of Illinois have observed that adolescence is a time of remodeling in the prefrontal cortex, a brain structure dedicated to higher functions such as planning and social behaviors.
The study of rats observed that both males and females lose neurons in the ventral prefrontal cortex between adolescence and adulthood, with females losing about 13 percent more neurons in this brain region than males.
This is the first study to demonstrate that the number of neurons in the prefrontal cortex decreases during adolescence. It is also the first to document sex differences in the number of neurons in the PFC. The study appears in the Feb. 9 issue of the journal Neuroscience.
Earlier studies in humans have found gradual reductions in the volume of the prefrontal cortex from adolescence to adulthood, said psychology professor and principal investigator Janice M. Juraska. "But the finding that neurons are actually dying is completely new. This indicates that the brain reorganizes in a very fundamental way in adolescence".
Juraska, graduate student Julie Markham and undergraduate student John Morris observed that the number of neurons decreased in the ventral, but not dorsal, prefrontal cortex during adolescence. The number of glial cells, which surround and support the neurons, remained stable in the ventral PFC and increased in the dorsal PFC.........
Posted by: Daniel Read more Source
March 6, 2007, 3:48 PM CT
Light-activated compound silences nerves
A compound that halts nerve cell activity only when exposed to light glows in this image of two nerve cells.
Credit: Washington University School of Medicin
Brain activity has been in comparison to a light bulb turning on in the head. Researchers at Washington University School of Medicine in St. Louis have reversed this notion, creating a drug that stops brain activity when a light shines on it.
The unexpected result, reported online in Nature Neuroscience, turned several lights on in researchers' heads.
"This is daydreaming at this point, but we might one day combine this drug with a small implanted light to stop seizures," says senior author Steven Mennerick, Ph.D. associate professor of psychiatry and of anatomy and neurobiology. "Some current experimental epilepsy therapys involve the implanting of an electrode, so why not a light?".
The new compound activates the same receptor used by a number of anesthetics and tranquilizers, making it harder for a brain cell to respond to stimulation. Mennerick and his colleagues including lead author Larry Eisenman, M.D., Ph.D., assistant professor of neurology, tested the drug on cells in culture set up to behave like they were involved in a seizure, with the cells rapidly and repeatedly firing. When they added the new drug and shone a light on the cells, the seizure-like firing pattern calmed.
If the drug is adapted for epilepsy, Mennerick notes, it is most likely to help in cases where seizures consistently originate from the same brain region. Theoretically, doctors could keep a patient on regular doses of the new drug and implant a small fiber optic light in the dysfunctional region. The light would activate the drug only when seizure-like firing patterns started to appear.........
Posted by: Daniel Read more Source
March 6, 2007, 3:31 PM CT
Receptor For Alcohol Pleasure And Problems
A genetic variant of a receptor in the brains reward circuitry heightens the stimulating effects of early exposures to alcohol and increases alcohol consumption, as per a new study by scientists at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). Conducted in rhesus monkeys, the study extends prior research that suggests an important role for a similar brain receptor variant in the development of human alcohol use disorders. A report of the findings is reported in the March, 2007 issue of the Archives of General Psychiatry.
"Eventhough the pathway to alcoholism is influenced by a number of factors, our findings affirm that individuals who possess this receptor variant may experience enhanced pleasurable effects from alcohol that could increase their risk for developing alcohol abuse and dependence," notes Markus Heilig, M.D., Ph.D., NIAAA Clinical Director and the studys senior author.
Molecules known as opioid peptides bind to opioid receptors in the brain to signal experiences of reward and reinforcement, as well as the euphoria and other positive subjective effects produced by alcohol. Prior studies have shown that, among the brains various subtypes of opioid receptors, the mu-subtype is most likely responsible for transmitting alcohols positive effects.........
Posted by: JoAnn Read more Source
March 5, 2007, 9:57 PM CT
Protein That Appears To Regulate Bone Mass Loss
Typically an estimated ten million americans suffer from osteoporosis, and another 34 million americans are at risk of developing the disease, which is characterized by a severe loss of bone mineral density, fragile bones and an increased risk of hip, spine and wrist fractures. The basic mechanism behind osteoporosis involves an imbalance between bone mineral formation and loss, but the detailed biological processes that lead to this imbalance are not completely understood. Now scientists at the National Institute of Allergy and Infectious Diseases (NIAID), one of the National Institutes of Health (NIH), and his colleagues are reporting new insights into the biology of bone loss based on a study of 14 people with a rare genetic disorder called X-linked Hyper IgM Syndrome.
X-linked Hyper IgM Syndrome strikes about one in a million American--all males--and is caused by a deficiency in an important immune system protein known as CD40 ligand. This protein is crucial for the development and maturation of immune cells, and without it people with X-linked Hyper IgM Syndrome are susceptible to a range of opportunistic infections. Last year, an NIAID doctor treating children with this disease found that several of them sustained unexplained rib fractures that he hypothesized could be, like osteoporosis, caused by a loss of bone mineral density. A new study, published online this week, confirms this unexpected connection. CD40 ligand appears to regulate cells that secrete chemicals that block bone metabolism, and the loss of this protein in people with X-linked Hyper IgM Syndrome appears to accelerate bone loss. The next step, say the researchers, is to determine whether experimental therapys designed to correct the immune deficiency of X-linked Hyper IgM Syndrome can also reverse the bone loss. If so, the knowledge gained from these studies may benefit people who are at risk of developing osteoporosis.........
Posted by: Janet Read more Source
March 5, 2007, 5:10 AM CT
Natural antibiotics yield secrets
Frog skin and human lungs hold secrets to developing new antibiotics, and a technique called solid-state NMR spectroscopy is a key to unlocking those secrets.
That's the view of University of Michigan researcher Ayyalusamy Ramamoorthy, who will discuss his group's progress toward that goal March 3 at the annual meeting of the Biophysical Society in Baltimore, Md.
Ramamoorthy's research group is using solid-state NMR to explore the germ-killing properties of natural antibiotics called antimicrobial peptides (AMPs), which are produced by virtually all animals, from insects to frogs to humans. AMPs are the immune system's early line of defense, battling microbes at the first places they try to penetrate: skin, mucous membranes and other surfaces. They're copiously produced in injured or infected frog skin, for instance, and the linings of the human respiratory and gastrointestinal tracts also crank out the short proteins in response to invading pathogens.
In addition to fighting bacteria, AMPs attack viruses, fungi and even cancer cells, so drugs designed to mimic them could have widespread medical applications, said Ramamoorthy, who is an associate professor of chemistry and an associate research scientist in the Biophysics Research Division.
While scientists have identified hundreds of AMPs in recent years, they're still puzzling over exactly how the peptides wipe out bacteria and other microbes. Unlike conventional antibiotics, which typically inhibit specific bacterial proteins, AMPs get downright physical with invaders, punching holes into their membranes. But they're selectively pugnacious, targeting microbes but leaving healthy host cells alone.........
Posted by: Mark Read more Source
March 1, 2007, 9:43 PM CT
Treating male infertility with stem cells
Los Angeles, CA -- New research has examined the usefulness of bone marrow stem cells for treating male infertility, with promising results. The related report by Lue et al, Fate of bone marrow stem cells transplanted into the testis: potential implication for men with testicular failure, appears in the recent issue of The American Journal of Pathology.
When a couple experiences infertility, the man is just as likely as the woman to be the cause. Male infertility may arise from failed proliferation and differentiation of the germ cells (precursors of sperm) or from dysfunction of the supporting cells. New research is looking to stem cells as a means of replacing nonfunctioning cells, whether germ cells or supporting cells.
Researchers, directed by Dr. Ronald S. Swerdloff of the Harbor-UCLA Medical Center, collected bone marrow stem cells from mice expressing the green fluorescent protein (GFP). These green cells, which could be easily tracked in recipient mice, were injected into the testes of infertile mice, in which infertility was induced either chemically or genetically (via mutations in a gene mandatory for sperm production).
The donor GFP-expressing cells took up residence in the testes and survived within the recipient mice for the entire 12-week study period. The donor stem cells displayed the characteristic shape of either germ cells or supporting cells, suggesting that the stem cells had differentiated. These differentiated donor (green) cells were also found near the native recipient cells of the same type, demonstrating that the local cellular environment likely influenced the fate of the donor stem cells.........
Posted by: Janet 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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