Changing Our Clocks: New Research Explores How Our Bodies Keep Time

February 11, 2008 — Our alarm clocks may spring forward on March 9, but our biological clocks may take longer to adjust. That's because our internal clocks are so tightly wound to many physiological and behavioral ... > full story

• HIV Drugs, Abacavir And Didanosine Increase The Risk Of Heart Attack, Study Suggests
• February 11, 2008 — A study to assess the adverse effects of anti-retroviral drugs shows that two widely-used HIV drugs are associated with an increased risk of heart attack/the formation of blood clots in the heart. ... > full story
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• New Therapy Possibilities For Lung Disease Patients
  February 11, 2008 — A new study may change current thinking about how best to treat patients in respiratory distress in hospital intensive care units. It has been commonly believed that high levels of carbon dioxide or ... > full story
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• How One Protein Binds To Genes And Regulates Human Genome
  February 11, 2008 — Out of chaos, control: Molecular biologists have discovered how a protein called PARP-1 binds to genes and regulates their expression across the human genome. Knowing where PARP-1 is located and how ... > full story
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• Discovery Of Good -- And Bad -- Liver Stem Cells Raises Possibility Of New Treatment
  February 11, 2008 — Many scientists believe up to 40 percent of liver cancer is caused by stem cells gone wild. Despite years spent looking, no one has ever found these liver "cancer stem cells." Now, researchers report ... > full story
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• Why Certain Ovarian Cancers Develop Resistance To Platinum-based Chemotherapy
  February 11, 2008 — Scientists have identified a new mechanism that explains why some recurrent ovarian tumors become resistant to treatment with commonly used platinum-based chemotherapy drugs such as cisplatin and ... > full story
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• Some 'Junk' DNA Is Important Guide For Nerve-cell Channel Production
  February 11, 2008 — Researchers have discovered that introns, or junk DNA to some, associated with RNA are an important molecular guide to making nerve-cell electrical channels. They hope to relate this knowledge to ... > full story
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• Drug-resistant E. Coli And Klebsiella Bacteria Found In Hospital Samples And Elsewhere In US
  February 11, 2008 — A research team examining bacterial isolates obtained in hospital and non-hospital clinical settings between 2000 and 2006, has identified drug-resistant strains of E. coli and Klebsiella bacteria in ... > full story
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• Artificial Sweeteners Linked To Weight Gain
  February 11, 2008 — Want to lose weight? It might help to pour that diet soda down the drain. Researchers have laboratory evidence that the widespread use of no-calorie sweeteners may actually make it harder for people ... > full story
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• New Virus Responsible For Deaths Of Transplant Recipients In Australia, Scientists Confirm
  February 11, 2008 — In the first application of high throughput DNA sequencing technology to investigate an infectious disease outbreak, scientists link the discovery of a new arenavirus to the deaths of three ... > full story

Diabetes Makes It Hard For Blood Vessels To Relax

ScienceDaily (Feb. 1, 2008) — One way diabetes is bad for your blood vessels is by creating too much competition for an amino acid that helps blood vessels relax, researchers say.

That amino acid, L-arginine, is broken down by the enzyme arginase to urea, which helps the body eliminate toxins resulting from the proteins we eat. Diabetics have a lot of arginase activity, which means they use a lot more L-arginine, says Dr. Maritza Romero, postdoctoral fellow at the Medical College of Georgia and lead author of the paper published in the current issue of Circulation Research.

It also means too little L-arginine is available to help nitric oxide synthase make nitric oxide, the powerful vasodilator that helps blood vessels relax, says Dr. Romero, who works in the lab of Dr. R. William Caldwell, chair of the MCG Department of Pharmacology and Toxicology and the study's corresponding author.

Researchers also found the amino acid, L-citrulline, as well as statins, compounds known to lower cholesterol, prevent elevation of arginase activity, restoring normal dilation abilities in animal models of type 1 diabetes. In fact, L-citrulline can be recycled into L-arginine.

Now they want to know specific factors and pathways involved in arginase activation and develop pharmaceutical agents to combat excessive arginase activity in diabetes. They also suggest clinical trials of L-citrulline as a supplemental therapy for diabetics with vascular problems.

Their findings also help explain why L-arginine supplement, marketed to treat hypertension, chest pain, heart failure and more, may not work long term. In the January 4, 2006 issue of the Journal of the American Medical Association, Johns Hopkins researchers reported that a clinical trial of patients taking an L-arginine supplement following a heart attack didn't improve in their vascular tone or their hearts' ability to pump. In fact, more patients died who were taking L-arginine than placebo and the study was closed with the recommendation the supplement not be used by heart attack patients. The supplement still is widely marketed.

"The findings of increased arginase I activity in diabetes may limit other therapeutic approaches proposed for early endothelial dysfunction such as oral L-arginine supplementation," Drs. Thomas L. Luscher and Jan Steffel, of the University of Zurich Cardiovascular Research Institute write in an accompanying editorial. "Although dietary L-arginine supplementation has been shown to exert vascular protective effects in certain clinical settings, this approach is unlikely to be effective in diabetes, if the results of this study can be confirmed by patients in vivo. In fact, the findings of Romera et al may provide a possible explanation for the unexpected neutral or even adverse effects of oral L-arginine in some clinical studies, in particular patients with coronary artery disease and infarction."

A short intravenous course of L-arginine may provide short-term improvement in blood vessel tone, Dr. Romero notes. However most of L-arginine ingested goes directly to the liver to be broken down, not the bloodstream where it can promote relaxation of blood vessels, Dr. Romero says.

Arginase also is associated with vascular problems related to aging, hypertension, sickle cell disease, atherosclerosis and erectile dysfunction, Dr. Romero says. L-citrulline already is taken by some sickle cell patients to reduce breath-taking fibrosis in their lungs. In addition to helping the body turn toxins into urea that can be safely eliminated from the body, arginase also helps in collagen formation and cell proliferation, but too much can be bad. In fact, Drs. Caldwell and Romero are pursuing studies of how increased arginase activity may harden blood vessel walls.

Adapted from materials provided by Medical College of Georgia.

Taking More Than One Anti-inflammatory Drug May Lead To Complications

February 2, 2008 — A new study found that taking two NSAIDs was associated with lower scores on a health-related quality of life assessment. Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to treat arthritis, ... > full story

• Study Paves Way For Development Of Macular Degeneration Cures
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• Virtual Human In HIV Drug Simulation
  February 2, 2008 — The combined supercomputing power of the UK and US 'national grids' has enabled scientists to simulate the efficacy of an HIV drug in blocking a key protein used by the lethal virus. The method -- an ... > full story
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• People Had More Intense Dreams After Sept. 11, 2001, Sleep Research Shows
  February 2, 2008 — The terrorist attacks of Sept. 11, 2001, changed our lives in a number of different ways, not only socially and politically, but also in the way in which we dream. According to the results, dreams ... > full story
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• Smoking Can Double Risk Of Colorectal Polyps
• February 2, 2008 — Smokers have a two-fold increased risk of developing colorectal polyps, the suspected underlying cause of most colorectal cancers, according to a new ... > full story
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• Anemia Treatment May Improve or Worsen Disease, Based on Timing
• February 2, 2008 — A treatment commonly given for anemia, promotes blood-vessel growth in the eye, an effect that could either improve/worsen disease for patients with cancer, diabetic retinopathy, or retinopathy of ... > full story
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• Chronic Insomnia Can Predict Future Functioning Of Adolescents
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• Protein Associated With Poor Breast Cancer Prognosis
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• Expression Patterns Of MicroRNAs Appear Altered In Colon Cancer, And Associated With Poor Outcomes
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• New Gene Linked To Fragile X Syndrome -- Suggests Potential Targets For Autism And Other Neurological Disorders
  February 1, 2008 — Scientists have discovered a new gene involved in fragile X syndrome, a condition that often shares many symptoms of autism. The discovery may lead to new tests or treatments for several neurological ... > full story