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June 13, 2005

Nitric Oxide Finding May Yield Better Cancer Treatments and Blood Substitutes

Topics: Medicine

Reduced oxygen in tissues can decrease the efficacy of cancer treatments, including radiation and some forms of chemotherapy. But Duke University Medical Center researchers have demonstrated how to safely deliver more oxygen to oxygen-deprived tissues in the body, a finding that could lead to more effective blood substitutes, wound healing therapies and cancer treatments.

Oxygen is critical to proper functioning and healing of all tissues in the body, but altering its levels with current therapies can elevate blood pressure and constrict blood vessels - serious risks for heart disease. Additionally, such effects reduce the efficacy of many cancer therapies, including radiation and some forms of chemotherapy.

The Duke team showed that simply adding a molecule called nitric oxide to the blood's hemoglobin can make it deliver more oxygen to tissues -- without boosting heart rate or constricting blood vessels. Hemoglobin is the blood's oxygen-carrying component.

(...) "Hemoglobin needs its natural partner in the blood, nitric oxide, to do its job of delivering oxygen to tissues, but current treatments deliver hemoglobin without nitric oxide.

(...) "Hemoglobin by itself actually reduces oxygenation to tissue because it constricts blood vessels, reducing blood flow." Thus, when delivered alone, hemoglobin may cause potentially fatal side effects and limit the effectiveness of radiation and chemotherapy.

(...) "If we could raise the level of tumor oxygenation before radiation, we would have a better chance of killing more of the cancer cells," added Dewhirst.

(...) The team hypothesized that hemoglobin containing nitric oxide would hold onto its oxygen until reaching the hypoxic environment of the tumor. Once there, it would release nitric oxide and dilate blood vessels to increase oxygen delivery.

(...) The researchers confirmed this scenario by comparing the effects in animals of pure oxygen versus injections of combined hemoglobin and nitric oxide. The pure oxygen, breathed in naturally, raised the level of circulating oxygen, but not oxygen levels in the arteries feeding the tumor. The hemoglobin plus nitric oxide, by contrast, raised oxygen levels in the tumors.

(...) "This is the strongest proof yet that hemoglobin senses oxygen levels and unloads nitric oxide when oxygen levels are low," said Sonveaux.

(...) "These results open up the possibility of using nitrosohemoglobin therapeutically in patients where there is not adequate oxygen perfusion to tissue.

More ...

Cross posted to NewHopeBlog

Posted by Hyscience at June 13, 2005 11:55 AM



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