Turning Mosquitoes Against Malaria
Mosquitoes spread malaria, but soon they may be used to stop it.
Previous attempts have been made to infect mosquitoes with bacteria that kill malaria parasites with the hope that such an approach would halt transmission of the disease. But researchers have had difficulty getting such infections to pass through multiple generations of mosquitoes.
As reported in Science by Zhiyong Xi, PhD, of Michigan State University, and colleagues, that obstacle has been overcome. Using an embryo microinjection technique, they successfully infected Anopheles stephensi mosquitoes -- the primary vectors for spreading malaria in the Middle East and South Asia -- with the bacterium Wolbachia, and the infections were passed through 34 generations by the end of the study.
Infected mosquitoes became resistant to the malaria parasite Plasmodium falciparum. When they were introduced into uninfected populations, the bacterial infection spread to 100% of mosquitoes within eight generations.
The study "offers a potential approach to permanently reduce the vectorial capacities of dominant malaria vectors in sub-Saharan Africa, one of the most challenging goals in current malaria vector control," the authors wrote.
-- Todd Neale
Stem Cells Versus Gliomas
High-grade gliomas are hard to treat because they can't be cured by surgery, and toxicity limits the effectiveness of chemotherapy. Now researchers led by Karen Aboody, MD, of City of Hope National Medical Center in Duarte, Calif., think they may have found at least a partial solution to the latter problem.
Neural stem cells are known to migrate to tumor sites and might therefore be useful in targeted chemotherapy, they report in Science Translational Medicine. So they modified neural stem cells to express cytosine deaminase, an enzyme that converts the oral prodrug 5-fluorocytosine to its active form, the common chemotherapy agent 5-fluorouracil.
In mice with glioma, they reported, the average tumor volume in animals that got the modified cells was about 30% smaller than in control animals. There was no evidence of toxicity attributable to the cells. Based on the preclinical work, the researchers reported, a phase I study in people with recurrent glioma has been approved.
-- Michael Smith
Stun Guns May Kill
Tasers and other "stun gun" devices that deliver brief, heavy, electric shocks -- used by police to incapacitate aggressive suspects -- may be less safe than commonly believed, a study in pigs suggested.
Some researchers have warned that the shocks from these devices could trigger cardiac arrhythmias, but no firm evidence has come forth. Now, researchers at Toronto General Hospital in Canada have run tests in anesthetized pigs, with results suggesting a genuine danger.
According to a presentation at the Heart Rhythm Society's annual meeting this week, the group placed sensors in the pigs' hearts and then zapped the animals with one of the devices. They found that even very short discharges from the devices altered cardiac rhythms, even within a single cardiac cycle.
Specifically, out of 38 discharges, four produced temporary bursts of ventricular tachycardia. "These results suggest that there is no discharge duration that is safe for stun gun discharges across the chest," they concluded.
-- Crystal Phend and John Gever
Grapes Heal the Wrath of Heart Failure
A grape-enriched diet helped turn on a cascade of cardioprotective processes that had depleted at the onset of hypertension-related heart failure, according to a rat study in the Journal of Nutritional Biochemistry.
E. Mitchell Seymour, PhD, of the University of Michigan Cardiovascular Center in Ann Arbor, and colleagues previously found that grapes reduced hypertension-associated diastolic dysfunction. However, they didn't know if the mechanism was associated with the reduction of hypertension or was a process more specific to the heart.
They found that phytochemical-rich grapes increase the presence of cardiac-specific gene expressions and proteins related to antioxidant defense.
The researchers hypothesized that it is the whole grape, rather than any of its individual components, that is responsible for the cardioprotective benefit.
-- Chris Kaiser
Immune Cells Boost Atherosclerosis in Diabetes
High blood sugar may ramp up production of certain immune cells, which could play a role in atherosclerosis in patients with diabetes, researchers found.
Diabetic mice had increased numbers of circulating neutrophils and monocytes, Ira Goldberg, MD, of Columbia University, and colleagues reported in Cell Metabolism.
They identified a possible molecule mediating this effect. Neutrophils secrete S100A8/S100A9, which interacts with the Receptor for Advanced Glycation Endproducts (RAGE) on bone marrow cells, stimulating monocyte production. These cells impair healing of plaques, the researchers said.
Treating hyperglycemia in the animals reduced monocytosis, diminished the entry of monocytes into atherosclerotic lesions, and promoted disease regression, the researchers reported.
"Both this molecule and its receptor in the bone marrow could be targeted to prevent the inflammation that occurs with type 1 diabetes," Goldberg said in a statement.
-- Kristina Fiore
New Method Improves Microbial Genome Sequencing
A barrier to rapid, accurate sequencing of bacterial and fungal genomes appears to have been broken down, according to a paper published this week in Nature Methods.
Previously, the best rapid sequencing method involved producing large numbers of short "reads" within a bacterium's genome, and then stitching them together. But this method often left gaps and had difficulty coping with repetitive and palindromic sequences. Longer reads could eliminate the gaps, but they were prone to errors under existing methods.
In the new study, researchers led by Jonas Korlach, PhD, of Pacific Biosciences in Menlo Park, Calif., hit on a way to paste much longer reads (more than 3,000 base pairs in length, on average) together while reducing errors to nearly zero.
To do so, they used Pacific Biosciences' Single Molecule Real-Time sequencing technology to generate many reads of an E. coli genome. The longest reads were pasted together to cover the entire genome, and accuracy was then checked using shorter reads from the same library.
With interest increasing in using genomic information to track disease outbreaks in real time, the method could provide a boost to such investigations.
-- John Gever