From a new twist on an ancient concept — thinking caps — to tapeworms as treatment, here is this week's collection of the latest research news collected by the MedPage Today staff.
Time to Put on Your Thinking Cap?
People solved three times as many unfamiliar or difficult problems as a control group when exposed to direct electrical brain stimulation, Australian researchers reported.
Study participants solved 60 percent of the problems on a validated math test when a weak electrical current was applied to the scalp. With sham stimulation, participants in the control group solved 20% of the same problems within the allotted time (P=0.022).
When the study was repeated with simpler problems, 85 percent of the test group versus 45 percent of the control solved the problems, as reported online in PLoS ONE.
The findings support the concept that simultaneous inhibition of certain nerve pathways, while opening up the throttle on others, removes the constraints of preconception and learned processes and provides access to a level of perception normally hidden by conscious awareness. That's a complicated way to describe the more familiar term "thinking outside the box," said Dr. Richard Chi, and Dr. Allan Snyder, of the University of Sydney.
"Our observations are strongly influenced by our preconceptions," the authors wrote in the background of their report. "Information consistent with our expectations or mental templates is often accepted at face value, whereas inconsistent information is discounted or hidden from conscious awareness. "While this hypothesis-driven mechanism helps us in efficiently dealing with the familiar, it can prevent us from seeing better solutions in a different and/or unfamiliar context."
The authors hope to gain more insight into the underlying mechanisms of their observations by conducting additional studies with simultaneous brain imaging.
— Charles Bankhead
Genome Leader Nothing to Crab About
A microscopic crustacean — Daphnia pulex or water flea — is leading the genome-size sweepstakes, with at least 30,907 genes, researchers are reporting in Science. In contrast, we humans have about 23,000.
The genetic excess is apparently a result of an elevated rate of gene duplication and the extra genes play a role in allowing the animal to cope with environmental stress, including such things as water pollution.
The water flea has been used as a sentinel animal to monitor the integrity of aquatic ecosystems — a sort of watery canary in the mine shaft — but it turns out that we share a number of the animal's genes. That means D. pulex could also be used to study how environmental issues directly affect human health, the researchers argued.
— Michael Smith
Epigenetics Give Mice the Blues
Getting depressed from chronic stress could be a matter not just of the genes but a sort of epigenetic modification of them by the environment, Japanese researchers reported in Neuron.
They found that two types of mice — one bred to be sensitive to stress and the other resilient to it — showed different responses to social and environmental stressors that were reflected in the level of activity of specific gene — glial cell-derived neurotrophic factor (Gdnf).
Reduced Gdnf resulted in depressed mice, but when the stress-prone mice were fed antidepressants, it was a happier day on the treadmill.
Similar effects may influence susceptibility or adaptation to chronic daily stressful events in humans, the researchers suggested. If so, these mechanisms could lead to novel approaches to treatment of depression, they noted.
— Crystal Phend
Building a Better Blood Vessel — Faster
While heart surgery patients can have the new blood vessels they need grafted from their own cells, the process can take up to nine months — time that these patients don't necessarily have.
So to make vessels more readily available, a team of researchers in Durham, N.C., grew tissue-engineered vascular grafts (TEVGs) by seeding a tube-shaped, biodegradable polymer scaffolding with smooth muscle cells from random donors.
The muscle cells produced collagen and other molecules that formed an extracellular matrix. When the scaffold degraded, the researchers used a detergent to strip away the initial muscle cells. The result: fully formed blood vessels that the researchers say are non-immunogenic, and thus can be implanted into any patient who needs them.
Researchers have used the technique to grow other organs, including livers and kidneys. Dr. Shannon Dahl, of Humacyte, Inc., in Durham, N.C., and colleagues, reported in Science Translational Medicine that the engineered blood vessels retained their strength and elasticity and remained unclogged after being stored in a salt solution for a year.
And when they tested the grafts in baboon heart surgery patients, they found restored blood flow and improved function for up to six months. They also showed no evidence of fibrosis or thickening of vessel walls.
"These data support a possible future use for decellularized human TEVGs in a range of vascular applications for patients who have no available autologus vascular conduit," they wrote.
— Kristina Fiore
Tapeworms — Mother Nature's Answer to Arthritis
Infection with a tapeworm called helminthic parasites may provide a new way of turning on the immune system to protect against joint inflammation, according to research conducted at the University of Calgary in Canada and reported this week in Arthritis & Rheumatism.
Chronic inflammation, whether of the intestinal tract, airway, or joints can occur when there is an imbalance in inflammatory and anti-inflammatory mediators. Attempts to target these mediators, such as with tumor necrosis factor inhibitors, are successful in many patients but can be very costly and can have potentially serious adverse effects.
The research team, led by Dr. Derek M. McKay, previously demonstrated that mice infected with tapeworms were protected against colitis, and two small clinical trials suggested that patients with colitis given whipworm ova had symptomatic improvement.
To see if arthritic symptoms also could be affected by helminth infection, the researchers chemically induced arthritis into the knees of mice, which resulted in swelling of the joints, decreased pain threshold, and increased production of inflammatory cytokines such as tumor necrosis factor.
In mice that had been treated two weeks earlier with Hymenoleptis diminuta the knee swelling was 35% to 40% less than in controls. In addition, when the helminths were given after the onset of arthritis, swelling significantly decreased within days. The response was equivalent to that seen after treatment with standard arthritis drugs and appears to result from a host immune response involving T cells, according to the researchers.
"The potential of helminth therapy in patients with arthritic disease in whom conventional treatments have failed is intriguing," they concluded.
— Nancy Walsh
Making Mice Realistically Diabetic
Animal research on type 1 diabetes has typically relied on brute-force models in which mice have their insulin-producing islet cells blasted away with chemicals such as streptozotocin.
For researchers interested in treatment that interrupt the autoimmune process that causes the human disease, such models aren't much use.
Now a research group has developed a more realistic model of type 1 diabetes in mice, according to their report this week in Science Translational Medicine.
The researchers, in France and England, engineered mice to express the epsilon chain of the CD3 protein, which is believed to be a key mediator of the immune process that eventually destroys pancreatic islet cells.
These animals spontaneously develop an autoimmune diabetes — which was reversed when the animals were treated with a monoclonal antibody called otelixizumab, which targets the CD3 protein.
According to the researchers, this mouse model will be key to determining whether CD3 is a realistic drug target for type 1 diabetes, which currently has no treatment other than insulin replacement.
— John Gever
An Escort for Tumor Killers
A common blood pressure medicine — losartan — may be useful in treating cancer patients by boosting the efficacy of cancer treatments that work by manipulating molecules within tumors.
The dense network of collagen fibers in many tumors impedes the penetration of these treatments, which are called nanotherapies.
As a possible solution to the problem, researchers led by Dr. Rakesh Jain, of Massachusetts General Hospital in Boston, evaluated the use of losartan, which is known to have antifibrotic activity in addition to lowering blood pressure.
Within cultures of breast cancer cells and within tumors implanted in mice, losartan inhibited the production of collagen by carcinoma-associated fibroblasts.
That was accompanied by improved distribution of two nanotherapies — oncolytic herpes simplex viruses injected directly into the tumors and IV-administered pegylated liposomal doxorubicin (Doxil).
Combining losartan and the IV treatment resulted in smaller tumors than those resulting from IV treatment alone.
"By ‘normalizing' the abnormal extracellular matrix of tumors, which keeps many therapies from reaching cancer cells, losartan improved both the delivery and efficacy of cancer nanotherapies," Jain said in a statement.
The findings were reported in the Proceedings of the National Academy of Sciences.
— Todd Neale