February 20, 2009, 6:18 AM CT
Bacteria with burglar's tools
Differences in the way they use their genes cause different strains of the E. coli bacterium to take on different hues. The beaker in the foreground contains strains of bacteria linked to urinary tract infections, while the background beaker holds more benign strains of bacteria isolated from the gut. Scientists are hoping to develop drugs that specifically target infection-causing strains of bacteria like those in the foreground beaker.
Credit: Michael Purdy/Washington University School of Medicine in St. Louis
Bacteria that cause urinary tract infections (UTIs) make more tools for stealing from their host than friendly versions of the same bacteria found in the gut, scientists at Washington University School of Medicine in St. Louis and the University of Washington have found.
The tools, compounds called siderophores, allow the bad bacteria to steal iron from their hosts, making it easier for the bacteria to survive and reproduce. But they also provide a potential way to target the bad strains of bacteria for eradication without adversely affecting the good strains, scientists report as per a research findings published online Feb. 20 by PLoS Pathogens
"When we treat an infection with antibiotics, it's like dropping a bombnearly everything gets wiped out, regardless of whether it's helpful or harmful," says main author Jeff Henderson, M.D., Ph.D., a Washington University infectious disease specialist who treats patients with UTIs at Barnes-Jewish Hospital. "We'd like to find ways to target the bad bacteria and leave the good bacteria alone, and these siderophores are a great lead in that direction".
UTIs are one of the most common infections, causing around $1.6 billion in medical expenses every year in the United States. Half of all women will experience a UTI at some point in their lives, and recurrent UTIs affect 20 to 40 percent of these patients. Researchers believe 90 percent of all UTIs are caused by the bacterium Escherichia coli
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February 19, 2009, 6:18 AM CT
Brain cancers linked to gene mutations
Researchers at the Johns Hopkins Kimmel Cancer Center and Duke University Medical Center have linked mutations in two genes, IDH1 and IDH2, to nearly three-quarters of several of the most common types of brain cancers known as gliomas. Among the findings: people with certain tumors that carry these genetic alterations appear to survive at least twice as long as those without them.
Further research on the genes could also lead to more precise diagnosis and therapys, they said.
Reporting in the Feb. 19 issue of the New England Journal (NEJM)
, researchers say they looked for IDH1 and IDH2 gene alterations in material taken from 500 brain tumors and 500 non-central nervous system cancers. They located changes in the IDH1 gene in more than 70 percent of three common types of gliomas: low-grade astrocytomas, oligodendrogliomas, and secondary glioblastomas. The changes occurred within a single spot along a string of thousands of genetic coding letters. Some of the brain cancers that did not have alterations in IDH1 had equivalent mutations in another closely related gene, IDH2.
"For patients with these types of common brain tumors, mutations of IDH1/IDH2 are the most frequent genetic alterations yet identified," says D. Williams Parsons, M.D., Ph.D., visiting professor in pediatric oncology at Johns Hopkins and assistant professor at Baylor College of Medicine.........
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February 19, 2009, 6:06 AM CT
Genetics comes to help in anticoagulant dosing
Each year in the United States, doctors start about 2 million patients on warfarin (Coumadin), an anticoagulant drug that's notoriously hard to administer. Now a study from the International Warfarin Pharmacogenetics Consortium (IWPC), which includes scientists from Washington University School of Medicine in St. Louis, confirms that using a patient's genetic information can make it easier to get the warfarin dose right.
"If the warfarin dose is too high, patients are at risk of hemorrhage, and if it's too low, they risk blood clots that can lead to stroke, heart attack or even death," says Brian F. Gage, M.D., associate professor of medicine at the School of Medicine and director of the outpatient Anticoagulation Service at Barnes-Jewish Hospital. "Unfortunately, getting the warfarin dose right is like walking a tightrope it's very easy to give too little or too much".
Doctors prescribe warfarin to prevent blood clots or reduce the risk of stroke in patients with atrial fibrillation or artificial heart valves and those with a history of blood clots in the legs or lungs. It is also helpful in preventing blood clot formation after certain orthopedic surgeries such as knee or hip replacement.
Recently, Gage, Charles Eby, M.D., associate professor of pathology and immunology, and his colleagues at the School of Medicine developed improved dosing formulas. They calculate the warfarin dose by taking into account the effect of two genes involved in warfarin sensitivity and metabolism. Their research demonstrated that gene-based dosing could more quickly and accurately estimate the appropriate dose of warfarin.........
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February 19, 2009, 5:58 AM CT
Medication used for blood pressure control may be useful in brain tumors
A widely used blood pressure medicine appears to be the key to preventing brain function loss common after radiation therapy, as per a newly published study by scientists at Wake Forest University Baptist Medical Center. The findings offer the hope of an improved quality of life for cancer patients.
Using a rat model, the study drew on a hypothesis from prior studies that a compound similar to the anti-hypertensive drug losartan can prevent the cognition loss that has been closely-linked to radiation treatment for brain tumor therapy.
The findings, recently reported in the International Journal of Radiation Oncology, Biology, Physics
, appear to validate the hypothesis in rats and scientists are optimistic that the same theory could easily be applied in a human clinical trial setting because the drug used has a long-established safety profile in patients who have taken it to treat high blood pressure.
"We need to kill cancer cells but also prevent or reduce therapy-related side effects," said Mike E. Robbins, Ph.D., a professor in the department of radiation oncology at the Brain Tumor Center of Excellence, part of Wake Forest University School of Medicine. "One very interesting feature of this compound is that it has never shown any pro-tumor effects. If anything, it appears to have anti-tumor properties. We're very close to having a compound that will protect the normal brain from cognitive injury as a result of radiation and, at the same time, we may very well increase the likelihood of one day curing brain cancer patients of their tumors."........
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February 18, 2009, 6:18 AM CT
Why do you experience fatigue with inflammatory disease?
Image showing a brain blood vessel (outlined in red) and a monocyte within the blood vessel and adherent to the vessel wall (yellow), and a monocyte within the brain after being recruited from the blood (green) in a mouse with liver inflammation.
Credit: The Journal of Neuroscience
people feel so tired and listless. Eventhough the brain is commonly isolated from the immune system, the study suggests that certain behavioral changes suffered by those with chronic inflammatory diseases are caused by the infiltration of immune cells into the brain. The findings suggest possible new therapy avenues to improve patients' quality of life.
Chronic inflammatory diseases like rheumatoid arthritis, inflammatory bowel disease, psoriasis, and liver disease cause "sickness behaviors," including fatigue, malaise, and loss of social interest. However, it has been unclear how inflammation in other organs in the body can impact the brain and behavior.
The scientists observed that in mice with inflamed livers, white blood cells called monocytes infiltrated the brain. These findings support prior research demonstrating the presence of immune cells in the brain following organ inflammation, challenging the long-held belief that the blood-brain barrier prevents immune cells from accessing the brain.
"Using an experimental model of liver inflammation, our group has shown for the first time the existence of a novel communication pathway between the inflamed liver and the brain," said the study's senior author Mark Swain, MD, Professor of Medicine at the University of Calgary.........
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February 12, 2009, 6:21 AM CT
Removing those skin wrinkles
As we get older, fat cells in the subcutaneous layer of the skin become smaller and fewer in number so that they are not longer able to "fill in" damage to the epidermal and dermal skin layers. The results are wrinkles and sagging.
Hollywood stars of a certain age take note: Research at Berkeley Lab suggests that a protein associated with the spread of several major human cancers may also hold great potential for the elimination of wrinkles and the rejuvenation of the skin. If this promise bears fruit, controlling concentrations of the RHAMM protein could one day replace surgical procedures or injections with neurotoxins that carry such unpleasant side-effects as muscle paralysis and loss of facial expressions.
RHAMM stands for Receptor for Hyaluronan Mediated Motility. Mina Bissell, a cell biologist with Berkeley Lab's Life Sciences Division and a leading authority on breast cancer, was collaborating with Eva Turley, an oncology professor at the University of Western Ontario and leading authority on tissue polysaccharides, on a study of the role that RHAMM plays in regulating the signaling of adipocytes (fat cells) during the repairing of tissue wounds from injuries such as skin cuts, heart attacks and stroke. Earlier research by Turley, who discovered RHAMM, had shown that over-expression of this protein points to a poor patient outcome for such human cancers as breast, colon, rectal and stomach.
In the course of their collaborative study, Bissell and Turley, working with mice, discovered that blocking the expression of the RHAMM protein - either by deleting its gene, or through the introduction of a blocking reagent - can be used to selectively induce the generation of fat cells to replace those lost in the aging process. At the same time blocking RHAMM expression also reduces deposits of unhealthy visceral fat.........
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February 12, 2009, 6:16 AM CT
New platinum compound to combat cancer
Scientists in the Department of Chemistry at Wake Forest University in collaboration with colleagues at the Wake Forest University Health Sciences Comprehensive Cancer Center have developed a new class of platinum-based anti-tumor drugs that animal studies have shown to be 10 times more effective than current therapys in destroying certain types of lung cancer cells.
The results were reported in the December 11 issue of the Journal of Medicinal Chemistry and highlighted in Science-Business eXchange (SciBX), produced by the publisher of the journal Nature. They suggest a new approach to fighting non-small cell lung cancer, which accounts for more than three-quarters of all lung cancers. Lung cancer is the leading cause of cancer-related deaths in both men and women. Less than a third of non-small cell patients with lung cancer respond to traditional platinum-based therapies, and those who do respond have a median survival of less than a year.
"We are able to slow the growth of this cancer substantially in mice," said principal investigator Ulrich Bierbach, Z. Smith Reynolds Foundation Fellow and associate professor of chemistry at Wake Forest. "That is very good news, since this is such a rapidly growing, intractable type of cancer".
The new compound's potency derives from its ability to rapidly bind with and disable a tumor cell's DNA before the cell's natural repair mechanisms are activated. That repair process causes drug resistance, which reduces the effectiveness of currently used platinum-based drugs.........
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February 12, 2009, 5:38 AM CT
Starving those cancer cells to death
The development of malignant tumours is highly dependent on the nutrients the tumours receive through the blood. The team of Dr. Janusz Rak, of the Research Institute of the McGill University Health Centre (MUHC) at the Montreal Children's Hospital, including Dr. Khalid Al-Nedawi and Brian Meehan, has just discovered a new mechanism that tumours use to stimulate the growth of the blood vessels that feed them. The scientists have also proposed a new way to control this process, which may translate into future therapies. These findings were published this week in the Proceedings of the National Academy of Sciences
).An innovative method
As per the researchers, tumour cells can release "bubbles" called microvesicles, which allow the tumours to communicate with the endothelial cells of blood vessels and stimulate changes in their behaviour. The microvesicles are armed with specific cancer proteins as they leave the tumour. When they are taken up by endothelial cells, the specific cancer proteins that they carry can trigger mechanisms that promote the abnormal formation of new blood vessels. The vessels then grow towards the tumour and supply it with the nutrients it requires to grow.
"We had already demonstrated the existence of these vesicles as well as their importance in the communication process between cancer cells and their environment. But this new discovery is much more targeted and represents a new direction in terms of treatment," said a delighted Dr. Rak.........
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February 11, 2009, 6:10 AM CT
Improve memory by increasing brain processing speed
Mayo Clinic scientists observed that healthy, elderly adults who participated in a computer-based training program to improve the speed and accuracy of brain processing showed twice the improvement in certain aspects of memory, in comparison to a control group.
"What's unique in this study is that brain-processing activities seemed to help aspects of memory that were not directly exercised by the program -- a new finding in memory research," says Glenn Smith, Ph.D., Mayo Clinic neuropsychology expert and lead researcher on the study.
The research, a controlled, multisite, double-blind study, would be reported in the recent issue of the Journal of the American Geriatrics Society
A copy is available online Feb. 9, 2009.
For an hour a day, five days a week for eight weeks, study participants worked on computer-based activities in their homes. The participants, from Minnesota and California, were age 65 or older. No one had a diagnosis of cognitive impairment, such as early Alzheimer's disease.
The control group, with 245 adults, watched educational videos on art, history and literature topics. They completed quizzes on the content.
The experimental treatment group, with 242 adults, completed six auditory exercises designed to help the brain improve the speed and accuracy of processing. For example, participants were asked to distinguish between high- and low-pitched sounds. To start, the sounds were slow and distinct. Gradually, the speed increased and separation disappeared.........
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February 10, 2009, 6:01 AM CT
Reading minds with infrared scan
Scientists at Canada's largest children's rehabilitation hospital have developed a technique that uses infrared light brain imaging to decode preference with the goal of ultimately opening the world of choice to children who can't speak or move.
As per a research findings published this month in The Journal of Neural Engineering,
Bloorview researchers demonstrate the ability to decode a person's preference for one of two drinks with 80 per cent accuracy by measuring the intensity of near-infrared light absorbed in brain tissue. http://www.iop.org/EJ/abstract/1741-2552/6/1/016003.
"This is the first system that decodes preference naturally from spontaneous thoughts," says Sheena Luu, the University of Toronto PhD student in biomedical engineering who led the study under the supervision of Tom Chau, Canada Research Chair in pediatric rehab engineering.
Most brain-computer interfaces designed to read thoughts require training. For example, in order to indicate yes to a question, the person needs to do an unrelated mental task such as singing a song in their head.
The nine adults in Luu's study received no training. Previous to the study they rated eight drinks on a scale of one to five.
Wearing a headband fitted with fibre-optics that emit light into the pre-frontal cortex of the brain, they were shown two drinks on a computer monitor, one after the other, and asked to make a mental decision about which they liked more. "When your brain is active, the oxygen in your blood increases and depending on the concentration, it absorbs more or less light," Luu says. "In some people, their brains are more active when they don't like something, and in some people they're more active when they do like something".........
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