October 9, 2008, 10:39 PM CT
A low-cholesterol diet leaves a bitter taste in the gut
One role for the proteins on the tongue that sense bitter tasting substances, type 2 taste receptors (T2Rs), is to limit ingestion of these substances, as a large number of natural bitter compounds are known to be toxic. T2Rs are also found in the gut, and it has been suggested that there they have a similar role to their function in the mouth (i.e., they might limit intestinal toxin absorption). Data to support this idea has now been generated in mice by Timothy Osborne and his colleagues, at the University of California, Irvine.
By supplementing the food that mice eat with the drugs lovastatin and ezetimibe (L/E), it is possible to reduce the amount of cholesterol that they take up, and they are therefore considered to be consuming a low-cholesterol diet. Such a diet increases the activity of the protein SREBP-2 in the gut. In this study, SREBP-2 was shown to directly induce the expression of T2Rs in cultured mouse intestinal cells as well as in the intestine of mice consuming food supplemented with L/E. In addition, SREBP-2 was shown to directly enhance T2R-induced secretion of the intestinal peptide cholecystokinin in both the cultured mouse intestinal cells and mice consuming food supplemented with L/E. As low-cholesterol diets are naturally composed of high amounts of plant matter that is likely to contain dietary toxins, and one function of cholecystokinin is to decrease food intake, the authors suggest that SREBP-2induced expression of T2Rs might provide a mechanism both to inform the gut that food-borne toxins could be present and to initiate a response that limits their absorption.........
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October 9, 2008, 10:28 PM CT
Communication Between Neurons And Muscle Cells
You can't raise a finger without your brain directing muscle cells, and researchers have figured out another reason that commonly works so well.
A neuron sends a message, or neurotransmitter, to the muscle cell to tell it what to do. To get the message, the receiving cell must have a receptor. Oddly, the unstable protein rapsyn is responsible for anchoring the receptor so it's properly positioned to catch the message.
Medical College of Georgia researchers have found what keeps rapsyn in proper conformation.
It is a heat shock protein, one of a large family of molecular chaperones that make sure proteins get where they are needed and do what they should, says Dr. Lin Mei, chief of developmental neurobiology at MCG and Georgia Research Alliance Eminent Scholar in Neuroscience.
Hsp90ß helps stabilize rapysn so receptors can get and stay where needed, as per research reported in the Oct. 9 issue of Neuron. Dr. Mei suspects that other hsp siblings have a similar caretaker role in neuron-to-neuron communication in the brain.
Researchers knew rapsyn's role in getting neuromuscular receptors to aggregate and stay where needed, but they didn't know what stabilized it. "It makes you wonder how to control this naughty boy which is very important," says Dr. Mei, the study's corresponding author.........
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October 9, 2008, 10:21 PM CT
Steroid Treatment Offers No Benefit In Preemies
Results of a multicenter study led by Johns Hopkins Children's Center challenge the longstanding practice of treating premature babies with hydrocortisone, a steroid believed to fight inflammation and prevent lung disease. The scientists observed that such therapy offers little or no benefit and that low cortisol levels are not even necessarily harmful. High cortisol levels, conversely, appeared to increase the risk of dangerous bleeding in the brain and require that babies be monitored aggressively to ward off life-threatening complications, as per the study reported in the recent issue of Pediatrics.
Premature babies and adults with a condition known as relative adrenal insufficiency have abnormally low levels of the stress hormone cortisol. The standard therapy for this condition in newborns has been hydrocortisone treatment. These findings, however, shed new light on the clinical meaning of low cortisol levels in preemies, showing that contrary to common belief, low blood concentrations of this hormone do not put extremely low-birth-weight babies (those born weighing less than 2.2 pounds) at higher risk for retinopathy of prematurity - a potentially blinding eye condition - inflammation and lung disease.
Scientists also found no difference in health outcomes between babies with low cortisol levels who were treated with hydrocortisone and those given a placebo. While hydrocortisone had no adverse effects on a baby's health, it also did nothing to prevent or reduce respiratory diseases, infections, hemorrhages or retinopathy.........
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October 8, 2008, 9:59 PM CT
Human Mind and Future Infrastructure Systems
The National Science Foundation (NSF) Office of Emerging Frontiers in Research and Innovation (EFRI) has announced 12 grants for fiscal year 2008, awarding a total of $23,779,056 over four years to 54 researchers representing 20 institutions.
Interdisciplinary teams will pursue transformative, fundamental research in two areas of great promise: understanding the brain and how its abilities may be used through cognitive optimization and prediction; and developing ways to make complex, interdependent infrastructure systems more resilient and sustainable.
What scientists learn from the brain may open a number of new paths of discovery, in areas such as computing, robotics, medicine and education. Understanding how the brain moves the hand, for example, could illuminate entirely novel ways to help people who are paralyzed or use prosthetic limbs. Understanding how the brain visually recognizes objects will enable advances in artificial vision systems, robotic intelligence and more.
The second area of research will examine complex challenges in our nation's interwoven infrastructures as demands on these interdependent systems are changing. Scientists will investigate how to increase their resiliency and sustainability as, for example, numerous electric vehicles interact with the power grid. In addition to drawing electricity from the grid, electric vehicles may send stored energy to the grid. New research may find a role for these vehicles in stabilizing the electric power grid during a catastrophe and in managing fluctuations in electricity from renewable energy sources.........
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October 8, 2008, 9:43 PM CT
Women, the elderly and weekend admissions
Women, the elderly, and patients admitted to the emergency department on weekends are all less likely to receive same-day coronary angioplasty for a life-threatening heart attack in Florida, University of South Florida scientists found. Their study was published this month in the American Journal of Cardiology.
Angioplasty, also known according tocutaneous coronary intervention (PCI), uses a catheter-guided balloon to open a blocked artery and restore blood and oxygen to the heart. A stent is commonly placed to hold open the artery. The procedure is the recommended therapy for the most serious and deadly of heart attacks known as ST-elevation myocardial infarctions or STEMIs, as per guidelines published by the American College of Cardiology and the American Heart Association. Studies show that rapid access to PCI can reduce heart muscle damage, hasten recovery, improve survival and prevent long-term disability better than clot-busting drugs alone.
Elizabeth Pathak, PhD, and Joel Strom, MD, both of USF, examined same-day PCI rates in over 58,000 acute heart attack patients who were admitted to emergency rooms in more than 200 Florida hospitals from 2001 to 2005.
The study included men and women ages 18 and older from the three largest ethnic groups in Florida: whites, blacks, and Hispanics. The scientists observed that the use of same-day PCI for heart attack patients more than doubled -- from 20 percent to 40 percent -- during the study period.........
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October 8, 2008, 9:39 PM CT
Circadian clock may be critical for remembering
The circadian rhythm that quietly pulses inside us all, guiding our daily cycle from sleep to wakefulness and back to sleep again, may be doing much more than just that simple metronomic task, as per Stanford researchers.
Working with Siberian hamsters, biologist Norman Ruby has shown that having a functioning circadian system is critical to the hamsters' ability to remember what they have learned. Without it, he said, "They can't remember anything".
Though not known for their academic prowess, Siberian hamsters nonetheless normally develop what amounts to street smarts about their environment, as do all animals. But hamsters whose circadian system was disabled by a new technique Ruby and colleagues developed consistently failed to demonstrate the same evidence of remembering their environment as hamsters with normally functioning circadian systems.
Until now, it has never been shown that the circadian system is crucial to learning and memory. The finding has implications for diseases that include problems with learning or memory deficits, such as Down syndrome or Alzheimer's disease. The work is described in a paper published Oct. 1 online in the early edition of the Proceedings of the National Academy of Sciences
Ruby is lead author on the paper. Siberian hamsters, also known as dwarf hamsters, are about the size of a mouse.........
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October 8, 2008, 9:37 PM CT
Guidelines urge physical activity during pregnancy
Moderate physical activity during pregnancy does not contribute to low birth weight, premature birth or miscarriage and may actually reduce the risk of complications, as per a Michigan State University professor who contributed to the U.S. government's first-ever guidelines on physical activity.
Kinesiology professor James Pivarnik and doctoral students Lanay Mudd and Erin Kuffel wrote the section on pregnancy and postpartum activity as part of the 2008 Physical Activity Guidelines unveiled Oct. 7 in Washington, D.C., by the Department of Health and Human Services. Pivarnik, president-elect of the American College of Sports Medicine, attended the event and spoke on behalf of the organization and MSU.
"There has been quite a dramatic change in regards to pregnancy and exercise," said Pivarnik, who has studied the topic for more than 20 years. "While it used to be thought that avoiding exercise meant avoiding harm to the fetus, research now shows physical activity can not only improve health of the mother but also provide potential long-term benefits for the child".
Specifically, the guidelines call for women to get at least 150 minutes of moderate-intensity aerobic activity per week during pregnancy and the postpartum period, preferably spread throughout the week. In addition to health benefits, moderate physical activity also may reduce the length of labor, evidence suggests. The guidelines call for women to avoid doing activities that involve lying on their back after the first trimester and activities with high risk of falling or abdominal trauma.........
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October 8, 2008, 9:36 PM CT
Proteins in sperm unlock understanding infertility
Proteins found in sperm are central to understanding male infertility and could be used to determine new diagnostic methods and fertility therapys as per a paper published by the journal Molecular and Cellular Proteomics
(MCP). The article demonstrates how proteomics, a relatively new field focusing on the function of proteins in a cell, can be successfully applied to infertility, helping identify which proteins in sperm cells are dysfunctional.
"Up to 50 percent of male-factor infertility cases in the clinic have no known cause, and therefore no direct therapy. In-depth study of the molecular basis of infertility has great potential to inform the development of sensitive diagnostic tools and effective therapies," write co-authors Diana Chu, assistant professor of biology at San Francisco State University and Tammy Wu, post-doctoral fellow at SF State. The study is included in a special Oct. 10 issue of MCP dedicated to the clinical application of proteomics.
"We suggest how the study of proteins is useful in the clinic, to help people move from infertile to fertile and ultimately to help couples have a baby," Chu said. "The ultimate goal is that a doctor could be able to say to a patient, 'this is the protein that is misregulated in your sperm and this is the drug that corrects it or decreases the level of that protein.' Understanding sperm proteins also means that a doctor could be able to inform patients of the likely success rates of different fertility therapies, an important factor given the high cost of fertility therapys".........
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October 8, 2008, 9:34 PM CT
The pepperoni pizza hypothesis
What's the worst that could happen after eating a slice of pepperoni pizza? A little heartburn, for most people.
But for up to a million women in the U.S., enjoying that piece of pizza has painful consequences. They have a chronic bladder condition that causes pelvic pain. Spicy food -- as well as citrus, caffeine, tomatoes and alcohol-- can cause a flare in their symptoms and intensify the pain. It was thought that the spike in their symptoms was triggered when digesting the foods produced chemicals in the urine that irritated the bladder.
However, scientists from Northwestern University's Feinberg School of Medicine believe the symptoms -- pain and an urgent need to frequently urinate -- are actually being provoked by a surprise perpetrator. Applying their recent animal study to humans, the researchers believe the colon, irritated by the spicy food, is to blame.
Their idea opens up new therapy possibilities for "painful bladder syndrome," or interstitial cystitis, a condition that primarily affects women (only 10 percent of sufferers are men.) During a flare up, the pelvic pain is so intense some women administer anesthetic lidocaine directly into their bladders via a catheter to get relief. Patients typically also feel an urgent need to urinate up to 50 times a day and are afraid to leave their homes in case they can't find a bathroom.........
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October 7, 2008, 10:50 PM CT
Atomic-resolution views suggest function of enzyme
Iris of Eye with Model of GAF Domain
Image of the iris of researcher Clemens Heikaus' eye with a model of a GAF domain imbedded in the pupil. A messenger molecule binds to the GAF domain to regulate an enzyme, PDE6, that is central to the way light hitting the retina is converted to signals to the brain.
Credit: Brad Clifton
An atomic-resolution view of an enzyme found only in the eye has given scientists at the University of Washington (UW) clues about how this enzyme, essential to vision, is activated. The enzyme, phosphodiesterase 6 (PDE6), is central to the way light entering the retina is converted into a cascade of signals to the brain.
This particular form of the enzyme comes from the cone photoreceptors of the retina and has not been well-researched, in contrast to its rod form. Rods are involved in night vision and motion sensation; the cones are responsible for color sensitivity, visual acuity, daylight vision, and adjustment to bright light.
The section of the enzyme molecule that most interests the scientists is the so-called GAF A domain. A small messenger molecule, cGMP, binds to the GAF A domain to regulate the enzyme.
"The domain binds to this small molecule with extremely high sensitivity," said UW biochemist Clemens Heikaus, who along with Sergio E. Martinez, now a research associate at Rutgers, carried out the study. "From our structure, we can infer why it prefers cGMP over other messenger molecules." He added that the domain is quick in recognizing and responding to the messenger molecule to create an instantaneous flow of information to the brain.........
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