November 15, 2006, 9:32 PM CT
New Way To Manipulate DNA
Polymers, large molecules comprised of chains of repeating structures, are used in everything from the coatings on walls of ships and pipes to reduce flow drag to gene treatment.
But long polymer chains are subject to breakage, called scission, and a new study by the University of Michigan shows that as it turns out, much of what researchers previously thought about why polymers break when subjected to strong flows, such as waves crashing against a ship's bow, was wrong.
This is important for a few reasons, said Michael Solomon, associate professor in the Department of Chemical Engineering, Macromolecular Science and Engineering Program. Broken polymers don't function as intended, and if researchers don't know what causes them to break, they can't keep them from breaking, nor can they design them to break in specific places.
For the past 40 years, researchers have not understood exactly which forces caused scission, said Solomon, who is the co-author on a paper published last week in the Proceedings of the National Academy of Sciences. The paper, "Universal scaling for polymer chain scission in turbulence," defines which flow forces and at what levels those forces cause polymers to break in turbulence.
"This paper understands how they are breaking in a new way that resolves some issues that have been present for 40 years," Solomon said.........
Posted by: Scott Permalink Source
November 15, 2006, 5:10 AM CT
No Link Found Between Viagra and HIV
Erectile dysfunction (ED) medications known as Phosphodiesterase type 5 (PDE-5) inhibitors have been used by millions of men as safe and effective management options linked to high rates of patient and partner satisfaction. Recent reports have appeared, however, that some individuals have misused this class of drug, combining them with narcotics such as methamphetamines. These reports further note that such individuals may be, in particular, at an increased risk for HIV. If such claims of a large and expanding use of PDE-5 inhibitors are correct, this would signify an important public health concern.
A comprehensive, multi-disciplinary conference funded by the National Institutes of Health sought to determine whether the drug class of PDE-5 inhibitors was contributing to an overall increase in HIV infection. The results of this conference appear in the latest issue of The Journal of Sexual Medicine.
Convincing evidence was not found to support the conclusion that PDE-5 inhibitor use is a risk factor for HIV infection. For the large majority of men, PDE-5 inhibitor use is conducted in a stable, committed partner relationship. Under such circumstances, the risk of HIV infection is relatively small. Clinicians and educators did emphasize, however, the importance of safe sex practices for those engaging in risky sexual relations.........
Posted by: Janet Permalink Source
November 15, 2006, 5:01 AM CT
Obesity An Advantage In Hemodialysis Patients
Despite significant improvements in dialysis therapys, currently over 20% of the 350,000 maintenance hemodialysis (MHD) patients in the United States die each year. A study published in Hemodialysis International finds that this high mortality rate may be attributed to malnutrition.
MHD patients experience what has been termed the "obesity paradox," wherein obesity is linked to increased chance of survival. "A larger body fat mass as seen in obesity probably represents protective reserves that may mitigate the adverse effects of malnutrition in patients," as per Kamyar Kalantar-Zadeh M.D., author of the study.
MHD patients tend to have a high degree of protein-energy malnutrition and inflammation. The combination of these two conditions, termed Kidney Disease Wasting (KDW), leads to increased risk of death. On the other hand, it has been shown that an increase in protein intake yields the greatest survival in patients.
The study suggests that improved diet as well as appetite-stimulating agents may be a way to improve nutrition and, consequently, outcome in MHD patients. Understanding the factors that lead to KDW will be the key to improving survival in MHD patients, as well as in the 20 to 40 million Americans who exhibit similar risk-factor paradoxes such as those with chronic heart failure, AIDS, rheumatoid arthritis and malignancy.........
Posted by: Mark Permalink Source
November 15, 2006, 4:57 AM CT
New Angioplasty Procedure More Effective
Over the last several years angioplasty has exceeded coronary bypass surgery as the preferred way to treat coronary artery disease. The stents (narrow tubes inserted into the artery to facilitate blood flow) usually used in the procedure are less invasive than open-heart surgery and offer greater convenience to the patient and the ability to perform more complex procedures.
However, they are also more likely to lead to restenosis, a recurrence of artery clogging. As per findings in Journal of Cardiac Surgery, newly developed drug-eluting stents (DES) that release a drug directly to the injured blood vessels are less likely to lead to restenosis than traditionally used bare-metal stents (BMS). Controversy exists regarding the role of stents in the therapy of complex multi-vessel coronary artery disease and the potential for late complications.
While studies have observed that DES procedures limit restenosis and, consequently, improve quality of life, the associated medical care would cost patients an average of $900 more during the two-year period following the procedure than with BMS. This cost is expected to decrease within five years, however, rendering DES cost-neutral or cost-saving when in comparison to BMS.
Despite the positive outcomes linked to DES, the procedure should not be viewed as a replacement for surgery. DES have proven to be safe and effective over the short and medium term, but long term effects have not been sufficiently explored.........
Posted by: Daniel Permalink Source
November 15, 2006, 4:51 AM CT
Vascular Targeting Agent Halts Bone Metastasis
A novel vascular targeting agent completely prevented the development of bone tumors in 50 percent of the mice tested in a preclinical study, providing early evidence that it could treat, or thwart, growth of tumors in bone, a common destination for many cancers when they start to spread.
Scientists at The University of Texas M. D. Anderson Cancer Center published in the journal Cancer Research that this "Trojan Horse" agent, VEGF121/rGel, stopped specialized cells within the bone from chewing up other bone material to make room for the implanted tumor to grow.
Eventhough this study tested the ability of VEGF121/rGel to halt the growth of human prostate cancer cells in the bones of mice, researchers say it likely could help prevent the growth of other cancers in bones such as breast, multiple myeloma, lung and renal cell.
"A number of tumors invade bone in the same way, so these findings suggest it may be possible to shut down this process regardless of the tumor type," says the study's lead author, Michael G. Rosenblum, Ph.D., professor in the Department of Experimental Therapeutics. "If that could be done - and we are a long way from determining if it is possible - we may be able to offer the first therapy that specifically targets bone metastasis".........
Posted by: Janet Permalink Source
November 15, 2006, 4:47 AM CT
Enriching Education For Disadvanted
While studies have shown that disadvantaged children benefit from high-quality preschool programs, they would benefit even more if they had additional tutoring and mentoring during their elementary and high school years, as per research at the University of Chicago.
Scientists have previously noted that a number of of the advantages children receive from preschool experiences begin to wane as they continue through school. A study by James Heckman, a Nobel-Prize winning economist at the University of Chicago and an expert on early childhood education, now shows for the first time that systematic interventions throughout childhood and adolescence could sustain the early gains and build on them.
"Childhood is a multistage process where early investments feed into later investments. Skill begets skill; learning begets learning," wrote Heckman in the paper, "Investing in our Young People." Heckman, the Henry Schultz Distinguished Service Professor in Economics, co-wrote the paper with Flavio Cunha, a graduate student in economics at the University of Chicago. The study is being released in Washington, D.C. November 15 as part of a larger report by America's Promise Alliance's titled Every Child, Every Promise: Turning Failure into Action.
The scholars studied data from the 1979 National Longitudinal Study of Youth to estimate a model that would describe how different inputs contribute to the accumulation of abilities. They used the model to predict the outcomes of children born to disadvantaged mothers when the children received a variety of extra learning assistance. In particular, they simulated the potential outcome of continued high-quality interventions beyond preschool.........
Posted by: Janet Permalink Source
November 15, 2006, 4:42 AM CT
Nanoparticles To Target Brain Cancer
Tiny particles one-billionth of a meter in size can be loaded with high concentrations of drugs designed to kill brain cancer. What's more, these nanoparticles can be used to image and track tumors as well as destroy them, as per scientists at the University of Michigan Comprehensive Cancer Center.
Scientists incorporated a drug called Photofrin along with iron oxide into nanoparticles that would target malignant brain tumors. Photofrin is a type of photodynamic treatment, in which the drug is drawn through the blood stream to tumor cells; a special type of laser light activates the drug to attack the tumor. Iron oxide is a contrast agent used to enhance magnetic resonance imaging, or MRI.
"Photofrin goes into tumor blood vessels and collapses the vasculature, which then starves the tumor of the blood flow needed to survive. The problem with free photofrin treatment is that it can cause damage to healthy tissue. In our study, the nanoparticle becomes a vehicle to deliver the drug directly to the tumor," says study author Brian Ross, Ph.D., professor of radiology at the U-M Medical School and co-director of Molecular Imaging at the U-M Comprehensive Cancer Center.
Photofrin has been used to treat several types of cancer, including esophageal, bladder and skin cancers. It works by traveling through blood vessels until it reaches the vessels supplying blood to the tumor. When activated by light, the Photofrin collapses these blood vessels, starving the tumor of the blood it needs to survive.........
Posted by: Janet Permalink Source
November 15, 2006, 4:38 AM CT
Holiday Season Could Ring In 'Heartburn Season'
Making merry is often synonymous with overindulging whether from holiday feasts or rich desserts or alcoholic beverages ringing in the holiday season as "heartburn season".
Heartburn generally caused by naturally occurring acids splashing back up from the stomach is often marked by a characteristic burning sensation that sufferers describe as rolling up into their chest. Fatty foods play a starring role in this process.
"Most of the time heartburn is a nuisance, not a tremendous threat to your health," said Dr. Stuart Spechler, professor of internal medicine in digestive and liver diseases at UT Southwestern Medical Center. "I tell most of my patients that it's going to be a tradeoff is the food going to taste good enough to suffer through the heartburn?
"If you know you're going to eat something that ordinarily gives you heartburn, there are medications that you can take before eating that food that might help".Prevention now emphasized
For decades, the plop-plop-fizz-fizz approach of antacids taken after people already were experiencing heartburn was the only treatment available. Emphasis has since shifted to prevention.
Those who are planning to indulge in foods likely to cause them heartburn can now take a histamine receptor blocker (H2 blockers), which slow the production of stomach acid and are generally available over the counter.........
Posted by: Sue Permalink Source
November 15, 2006, 4:31 AM CT
Vaccine Against Colorectal Cancer
British scientists have developed a vaccine that stimulates colorectal cancer patients' immune systems to fight malignant cells.
In a clinical trial of 67 patients, scientists at the University of Nottingham found that when the vaccines were administered before and after surgery to remove malignant tumors, they helped stimulated immune cell production in up to 70 percent of patients. These results are reported in the November 15 issue of Clinical Cancer Research.
"This is the first vaccine shown to stimulate TNF-alpha an immune-system protein that is very effective at killing cancer cells," said Lindy Durrant, senior author of the study and professor of cancer immunotherapy at the university.
The vaccine works by stimulating the patients' immune response to generate infection-fighting white blood cells called T cells, which in turn produce immune system proteins called cytokines that destroy cancer cells. The antibody contained in the vaccine, called 105AD7, was cloned from a patient who survived seven years with liver metastases from colorectal cancer, Durrant explained.
"This is very unusual as most patients die within one year of getting liver metastases," she said. "I thought if this antibody had helped this patient, if we could clone it, it might help others".........
Posted by: Sue Permalink Source
November 14, 2006, 4:54 AM CT
Sibling relationships reflect family dynamics
Most children in the United States grow up with sisters and brothers. Connections that commonly last a lifetime, these relationships can be strained at times, particularly during childhood. New research concludes that sibling ties are best understood in the context of their families, and that efforts to improve relationships should take into account not just the siblings, but the family as a whole.
This research also observed that, overall, sisters feel closer to their siblings than do brothers, and that relationships between sisters and brothers become closer in later adolescence. Further, for all siblings, discord is highest when the first-born child is about 13 and the second-born is about 10.
As published in the November/December 2006 issue of the journal Child Development, scientists at Pennsylvania State University interviewed mothers, fathers, and first- and second-born children in 200 white, working- and middle-class, two-parent families. During the course of the study, first-born children ranged from 10 to 19 years of age, with an average age of 12 at the start of the study and 17 at the end. Second-born children ranged from 7 to 17 years of age during the study, with an average age of 9 at the start and 15 at the end.Among the study's key findings are:
Posted by: JoAnn Permalink Source