Link between mitochondria and tumors found

BETHESDA, Md., -- U.S. scientists say they have discovered a link between stem cell potency and the metabolic rate of their mitochondria. The scientists said they discovered stem cells with more active mitochondria have a greater capacity to differentiate and are more likely to form tumors. The researchers led by Dr. Toren Finkel at the National Heart, Lung and Blood Institute said they sorted mouse embryonic stem cells by their mitochondrial potential -- the amount of voltage going across mitochondrial membranes, similar to how nerve activity is measured. They found both visually and in the expression of key stem cell markers, low and high metabolism stem cells were indistinguishable. But, when tran- splanted into mice, the researchers said the two types of cells had contrasting properties, as cells with lower meta- bolic rates were more efficient at differentiating into other cell types and the highly metabolic cells were more prone to keep dividing and form teratomas -- tumors characterized by having various tissue types mixed together. Although the study was conducted with mouse cells, the researchers said they expect a similar relationship to hold true in human stem cells. The study appears in the Journal of Biological Chem- istry.

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Body's natural anti-HIV enzyme is examined

LOS ANGELES, -- U.S. medical scientists say they've deter- mined the atomic structure of a key enzyme involved in in- hibiting the human immunodeficiency virus. The researchers, led by Professor Xiaojiang Chen of the University of South- ern California, said the enzyme APOBEC-3G -- present in every human cell -- is capable of stopping HIV at the first step of replication, when the retrovirus transcribes its RNA into viral DNA. The reason APOBEC-3G works so well, but peo- ple still develop AIDS, is because the HIV virus has evolved to encode the protein Vif, which blocks APOBEC-3G. But Chen said his group's research offers important clues on where Vif binds to APOBEC-3G. Those findings, he said, could be used to design drugs that would prevent Vif from binding, allowing APOBEC-3G to do its job. That, he added, would un- lock humans' innate ability to fight HIV. The study that included Lauren Holden, Courtney Prochnow, Y. Paul Chang, Ronda Bransteitter, Linda Chelico, Udayaditya Sen and Pro- fessors Raymond Stevens and Myron Goodman appears in the online edition of the journal Nature.

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FDA reviews Enbrel, Humira and Remicade

WASHINGTON, -- The U.S. Food and Drug Administration has announced a safety review of several drugs known as tumor necrosis factor, or TNF, blockers. The agency said the drugs -- Enbrel, Humira and Remicade -- are being reviewed for a possible association with development of lymphoma and other cancers in children and young adults treated for juvenile idiopathic arthritis and Crohn's disease. The drugs suppress the immune system by blocking the activity of TNF, a substance in the body that can cause inflammation and lead to immune system-related diseases. The FDA said it has asked the makers of the TNF blockers to supply information about all cases of cancer reported in children and young adults taking TNF blockers. While the review is ongoing, FDA advises doctors to weigh the possible association with lymphoma and other cancers against the benefits of treatment when prescribing TNF blockers to children and young adults. Enbrel is manufactured by Amgen and Wyeth Pharmaceuticals, Humira is produced by Abbott Laboratories and Remicade is manufactured by Centocor Inc.

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New research in otolaryngology is reported

ALEXANDRIA, Va., -- The American Academy of OtolaryngologyHead and Neck Surgery has detailed three studies focusing on tongue cancer, ear infections and hearing implants. The Virginia-headquartered academy said University of MilanoBicocca researchers in Italy have found although oral cancer is more prevalent in men, gender does not influence prognosis. Based on this, the researchers concluded that employing a less aggressive course of treatment in female patients with tongue cancer is not justified. A second study by Taiwanese scientists looks into speech performance when using digital hearing aids among the "young elderly" -- those in the 65-80 age group -- compared with people more than 80 years of age. The study showed age plays no role in the improvement of a patient's ability to hear with hearing aid implants. A third study focuses on pediatric care, looking into the cause and treatment of chronic ear infections where fluid is present behind a child's ear drum. Results of the study conducted by Australian researchers indicate the presence of intracellular bacteria in the middle ear plays an important role in the development of inflamed tissue and mucus in the area. The studies appear in the journal Otolaryngology-Head and Neck Surgery.

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New technique for malaria control reported

LONDON, -- British scientists say they've demonstrated the feasibility of preventing malaria parasites from becoming sexually mature, thereby controlling the disease. Researchers at the London School of Hygiene & Tropical Medicine and the Wellcome Trust Sanger Institute said the parasite -- Plasmodium falciparum -- is responsible for more than a million malaria deaths a year. They said their discovery of a parasite enzyme could also have implications for controlling the spread of drug resistance. "The enzyme we have discov- ered, a protein kinasea, is essential for the development of malaria parasite gametes," said David Baker, senior author of the study. "Working with genetically modified parasites, in combination with inhibitors of this enzyme, we have demonstrated that it is feasible to block the sexual stage of the life cycle of the malaria parasite. "This has exciting implications in terms of improving how we go about tackling malaria," he added. "If a drug can be developed that targets this stage of the life cycle, and combined with a curative drug, it would be an important new approach for controlling malaria transmission and the spread of drug resistance." The findings appear in the journal PLoS Biology.

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Damaged brains helped by stem cell therapy

CHAPEL HILL, N.C., -- U.S. medical scientists say they have found a way in which neuronal stem cells in the adult brain might be used in treating brain injuries. According to some experts, newly born adult neuronal brain stem cells could help repair brain injuries, but first a way must be found to regulate the manner in which they are created -- a process known as neurogenesis. The researchers led by Laurence Katz of the University of North Carolina School of Medicine suggest a way in which that might be achieved. According to the study, neurogenesis can be regulated through induced hypothermia. In rat subjects, a mild decrease in body temperature was found to substantially decrease the proliferation of newly-born neurons, the researchers said. "Many questions remain before we adequately understand how to control these cells to repair a damaged brain," said Katz. "However, the findings represent an important step in demonstrating these cells can be controlled by simple external forces like hypothermia." He presented the findings last weekend in Washington during the annual meeting of the Society for Academic Emergency Medicine. Abstracts of that presentation appear in the May supplemental issue of the journal Academic Emergency Medicine.

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