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Agent orange chemical, dioxin, attacks the mitochondria to cause cancer, says Penn research team

Contact: Jordan Reese
jreese@upenn.edu
215-573-6604
University of Pennsylvania

PHILADELPHIA— Researchers with the University of Pennsylvania School of Veterinary Medicine have demonstrated the process by which the cancer-causing chemical dioxin attacks the cellular machinery, disrupts normal cellular function and ultimately promotes tumor progression.

The team identified for the first time that mitochondria, the cellular sub-units that convert oxygen and nutrients into cellular fuel, are the target of tetrachlorodibenzodioxin, or TCDD. The study showed that TCDD induces mitochondria-to-nucleus stress signaling, which in turn induces the expression of cell nucleus genes associated with tumor promotion and metastasis.

The mechanism the research team has described is directly relevant to understanding incidences of breast and other cancers in human populations exposed to these chemicals. With a better understanding of this underlying cellular mechanism, researchers hope to improve their understanding of tumor growth and promotion.

“Now that we have identified this signaling mechanism we can look at ways to disrupt this complex chain of events,” said Narayah Avadhani, chair of the Department of Animal Biology at Penn’s School of Veterinary Medicine and the study’s lead investigator. “Our ultimate goal is to block the propagation of this mitochondrial stress signaling and inhibit the expression of the proteins that combine to assist cancer growth.”

A well-characterized mechanism of TCDD action occurs through activation of arylhydrocarbon receptors, AhR, by directly binding to the protein subunits. Activated AhR mediates the transcriptional activation of many genes including those involved in fatty acid metabolism, cell cycle regulation and immune response. The present study, however, shows that TCDD starts the chain of events that promote tumor progression in vivo by directly targeting mitochondrial transcription and induction of mitochondrial stress signaling. A unique feature of this TCDD-induced signaling is that it does not involve the action of AhR but occurs through increased calcium levels in cells and activation of calcium responsive factors. A net result of signaling cascade is slowing down of cellular apoptosis, increased cell proliferation and tumor cell metastasis. Taken together, this study describes a novel mechanism of TCDD-induced tumor progression and emergence of metastatic cancer cells.

TCDD is the most toxic compound in the dioxin family. Formed as a by-product during waste incineration, paper, chemical and pesticide manufacturing, it was the toxic ingredient in Agent Orange and closed the Love Canal in Niagara Falls. The public health impact of dioxin, according to the Environmental Protection Agency, compares to that of the pesticide DDT.

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The study appears online and in the Dec. 17 issue of the Proceedings of the National Academy of Sciences and was performed by Avadhani, Gopa Biswas, Satish Srinivasan and Hindupur Anandatheerthavarada of the Penn School of Veterinary Medicine.

The research was supported by a grant from the National Cancer Institute and the National Institutes of Health.

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December 18, 2007 Posted by | Cancer, Cancer Biology, FMS Global News, Global, Global News, London, London UK Feed, National Cancer Institute, NIH, Ottawa, Ottawa City Feed, PTSD, RSS Feed, Toronto, Toronto City Feed, Washington DC, Washington DC City Feed, World News | , , , , | Leave a comment

Cholesterol-lowering drugs and the risk of hemorrhagic stroke

Contact: Angela Babb
ababb@aan.com
651-695-2789
American Academy of Neurology

ST. PAUL, Minn. – People taking cholesterol-lowering drugs such as atorvastatin after a stroke may be at an increased risk of hemorrhagic stroke, or bleeding in the brain, a risk not found in patients taking statins who have never had a stroke. But researchers caution the risk must be balanced against the much larger overall benefit of the statin in reducing the total risk of a second stroke and other cardiovascular events when making treatment decisions. The research is published in the December 12, 2007, online issue of Neurology®, the medical journal of the American Academy of Neurology.

For the study, researchers conducted a secondary analysis of the results of the Stroke Prevention with Aggressive Reduction in Cholesterol Levels (SPARCL) clinical trial. The trial enrolled 4,731 people who were within one to six months of having had a stroke or transient ischemic attack, or mini-stroke, and with no history of heart disease. Half of the participants received atorvastatin and half received a placebo. The participants were then followed for an average of four and a half years.

Overall, treatment was associated with a 16-percent reduction in total stroke, the study’s primary endpoint, as well as significant reductions in coronary heart events. However, secondary analysis found that the overall reduction in stroke included an increase in the risk of brain hemorrhage. Of those people randomized to atorvastatin, the study found 2.3 percent experienced a hemorrhagic stroke during the study compared to 1.4 percent of those taking placebo. The study also found there was a 21-percent reduction in ischemic stroke, a more common type of stroke involving a block in the blood supply to the brain, among people taking atorvastatin.

Other factors were also found to increase the risk of brain hemorrhage. For example, those who had experienced a hemorrhagic stroke prior to the study were more than five times as likely to suffer a second stroke of this kind. Men were also nearly twice as likely as women to suffer a hemorrhagic stroke. People with severe high blood pressure at their last doctor’s visit prior to the hemorrhagic stroke had over six times the risk of those with normal blood pressure.

“Although treatment of patients with a stroke or transient ischemic attack was clearly associated with an overall reduction in a second stroke, hemorrhagic stroke was more frequent in people treated with atorvastatin, in those with a prior hemorrhagic stroke, in men and in those with uncontrolled hypertension,” according to study author Larry B. Goldstein, MD, with Duke University Medical Center in Durham, North Carolina, and Fellow of the American Academy of Neurology. “This risk of hemorrhagic stroke also increased with age.”

“Treatment with atorvastatin did not disproportionately increase the frequency of brain hemorrhage associated with these other factors. The risk of hemorrhage in patients who have had a transient ischemic attack or stroke must be balanced against the benefits of cholesterol-lowering drugs in reducing the overall risk of a second stroke, as well as other cardiovascular events,” said Goldstein.

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The SPARCL trial was funded by Pfizer, the maker of atorvastatin.

The American Academy of Neurology, an association of more than 20,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer’s disease, epilepsy, Parkinson disease, and multiple sclerosis.

For more information about the American Academy of Neurology, visit http://www.aan.com.

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December 13, 2007 Posted by | American Academy of Neurology, Baltimore, Barcelona, Bethesda, Boston, Calgary, Canada, FMS Global News, France, Germany, Global, Global Health Vision, Global News, Hemorrhagic Stroke, Italy, London, London UK Feed, Medical Journals, Newfoundland, News, News Australia, News Canada, News France, News Germany, News Israel, News Italy, News Jerusalem, News Switzerland, News UK, News US, News USA, Nova Scotia, Ottawa, Ottawa City Feed, Quebec, Research, RSS Feed, Slovakia, Spain, Statin Drugs, Stroke, Toronto, Toronto City Feed, UK, US, Virginia, Washington DC, Washington DC City Feed, World News | , , | Leave a comment

Demand for Spanish-language cancer Web materials quadruples

Contact: Beth Bukata
bethb@astro.org
703-431-2332
American Society for Therapeutic Radiology and Oncology

Internet resources and access remain scarce

Although Spanish-speaking cancer patients are rapidly increasing their search for patient education resources on the Internet, there are very few Spanish-language Web sites available to provide this information, according to a study presented October 28, 2007, at the American Society for Therapeutic Radiology and Oncology’s 49th Annual Meeting in Los Angeles.

Spanish-speaking cancer patients were also shown to have more limited access to the Internet compared to English-speaking users of cancer information Web sites, based on the user patterns of the two groups.

“There is an urgent need for more Web-based information to be more available to Spanish-speaking patients with cancer, and Internet access needs to be more widely available,” said Charles Simone II, M.D., lead author of the study and a radiation oncologist at the Hospital of the University of Pennsylvania in Philadelphia. “The increased knowledge gained among these patients will help to eliminate healthcare disparities and lead to improved medical outcomes.”

The Spanish-language cancer information Web site, OncoLink en español, quadrupled their number of unique visitors last year, from 7,000 visitors per month in January 2006 to nearly 29,000 monthly visitors by the end of the year. More than 200,000 users visited the Web site in 2006.

In contrast, the English-language version of the site, OncoLink, had nearly 2 million visitors last year, although their number of unique visitors did not increase throughout the year. OncoLink en espanõl was launched in 2005 by OncoLink, one of the oldest and largest Internet-based cancer information resources. Both sites are managed by the University of Pennsylvania.

The study shows that OncoLink en español users were less likely to browse the Internet during weekends and morning hours, compared to the users who browsed OncoLink, suggesting that they are accessing the Internet more through work or specialized services.

In addition to when they accessed the Internet, OncoLink en español users also differed on the types of cancers they searched for, as well as the timing and method of their Internet search patterns.

“Awareness of these differences can assist cancer education Web sites to tailor their content to best meet the needs of their Spanish-speaking users,” said Dr. Simone.

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The study was carried out using AWStats, a Web-data analyzing program, to collect and compare statistical data from the secure servers of both language versions of OncoLink.

For more information on radiation therapy in English and in Spanish, visit http://www.rtanswers.org.

The abstract, “The Utilization of Radiation Oncology Web-based Resources in Spanish-speaking Oncology Patients,” will be presented for poster viewing starting at 10:00 a.m, Sunday, October 28, 2007. To speak to the study author, Charles Simone, II, M.D, please call Beth Bukata or Nicole Napoli October 28-31, 2007, in the ASTRO Press Room at the Los Angeles Convention Center at 213-743-6222 or 213-743-6223. You may also e-mail them at bethb@astro.org or nicolen@astro.org.

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October 29, 2007 Posted by | Cancer, Cancer Information In Spanish, FMS Global News, Global, Global Health Vision, Global News, London, London UK Feed, Lung Cancer, News, Oncology, Ottawa, Ottawa City Feed, Research, RSS Feed, Spanish, Toronto, Toronto City Feed, Washington DC City Feed | , , , | 7 Comments