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Friday, March 29, 2013
Tuesday, March 12, 2013
How Contagious Tasmanian Devil Cancer Goes Invisible
A cancer that has wiped out 70 percent of wild Tasmanian devils became contagious by "switching off" certain genes that would otherwise enable the immune system to recognize it, a new study finds.
Devil facial tumor disease is one of only two contagious cancers in the world (the other affects dogs and is nonfatal). It spreads when the Australian marsupials bite or nip each other, transmitting cancerous cells that grow into enormous face tumors. The cancer either metastasizes to other organs or prevents Tasmanian devils from eating or drinking. Either way, death usually occurs within six months. Experts predict the species could vanish within 20 years if the tumor disease isn't stopped.
The immune system should catch these tumor cells, but the cancerous invasion causes no immune response in devils, said Hannah Siddle, a University of Cambridge immunology researcher. Siddle and her colleagues have now discovered why: The tumor cells lack surface molecules called major histocompatibility complex molecules. These MHC molecules allow the immune system to detect the invading cells. Without them, the cancer is essentially invisible.
"That explains why the immune system of the devils doesn't recognize those DFTD (devil facial tumor disease) cells as foreign, as it should, or as cancerous, for that matter," Siddle told LiveScience.
But there is good news. Typically, cancer cells that ditch their surface coating of MHCs do so via a permanent genetic mutation. That's not the case for DFTD cells, said study researcher Jim Kaufman, also of Cambridge.
"What we stumbled on was the fact that the MHC molecules disappeared by regulation," Kaufman told LiveScience.
Regulating genes
In other words, the genes that hold the instructions for making the MHC molecules still exist in the cancer cells' genome. Those instructions simply aren't transcribed, and the molecules never form. What that means, Kaufman said, is that the cancer cells' invisibility is reversible.
The researchers proved the concept by using a communication protein called gamma interferon to "switch on" the MHC-coding genes in a culture of devil tumor cells in a Petri dish. The once-MHC-free cells started making MHC molecules again.?
In addition, the researchers examined tumor biopsies from wild Tasmanian devils and found that in some rare portions of tumor, immune cells were invading. In these areas, the cancer cells were making MHC molecules, suggesting that the genes can sometimes be spontaneously switched back on. It's not enough to save Tasmanian devils from death, but it does suggest hope for a vaccine, Kaufman and Siddle said. [See Photos of the Infected Tasmanian Devils]
"What we hope to do is to figure out a way to tip the balance so that the immune system does a better job of recognizing and can get rid of the tumor," Kaufman said. The researchers published the findings today (March 11) in the journal Proceedings of the National Academy of Sciences.?
Key to contagious cancers
Development is going to take some time, Siddle said, but the researchers suspect the MHC finding could be a key step to creating a vaccine for the disease in the wild. Currently, the only way to save Tasmanian devils from extinction is to keep non-infected captive populations in zoos.
The finding is also a useful weapon in the arsenal against human diseases, Kaufman said. The more known about a particular disease agent in animals, the better prepared scientists are to face it should it ever strike humans. When the human immunodeficiency virus (HIV), a lentivirus, appeared on the scene, lentiviruses were largely a mystery, Kaufman said. It took years to catch up on a basic understanding of how the disease worked as humans died. In contrast, health professionals were much better prepared for the emergence of mad cow disease, because similar disorders such as scrapie had been studied in sheep and goats.
"There aren't any contagious tumors in humans yet," Kaufman said. "But one never knows when one is going to arise, whether it's next year or 1,000 years from now."
Follow Stephanie Pappas @sipappas. Follow LiveScience on Twitter @livescience, Facebook?or Google+. Original article on LiveScience.com.
Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.Source: http://news.yahoo.com/contagious-tasmanian-devil-cancer-goes-invisible-191803176.html
Last anti-Chavez TV station to be sold
FILE - In this Oct. 3, 2003 file photo, an employee at Globovision, a 24-hour television news channel, works behind a glass reading "News" with Globovision's logo "G" at the channel's headquarters in Caracas, Venezuela. Employees of the last remaining opposition television channel in Venezuela said on March 11, 2013 that it is being sold to a businessman friendly to the government. The employees said the sale would occur after April 14 elections, which Hugo Chavez's hand-picked successor is favored to win. (AP Photo/Leslie Mazoch, File)
FILE - In this Oct. 3, 2003 file photo, an employee at Globovision, a 24-hour television news channel, works behind a glass reading "News" with Globovision's logo "G" at the channel's headquarters in Caracas, Venezuela. Employees of the last remaining opposition television channel in Venezuela said on March 11, 2013 that it is being sold to a businessman friendly to the government. The employees said the sale would occur after April 14 elections, which Hugo Chavez's hand-picked successor is favored to win. (AP Photo/Leslie Mazoch, File)
CARACAS, Venezuela (AP) ? The only remaining pro-opposition television channel in Venezuela, Globovision, is being sold to an insurance company owner friendly with the government, employees told The Associated Press on Monday.
They said its editorial line is sure to change and that many journalists sobbed when informed of the sale, certain some would lose their jobs.
The sale will occur after April 14 elections, which Hugo Chavez's hand-picked successor, Nicolas Maduro is highly favored to win, they said.
International human rights and press freedom groups have accused Chavez and his political heirs of trying to strangle Globovision financially by inventing alleged transgressions. Under constant state pressure, it has been forced to pay millions of dollars in fines.
The state telecommunications agency has repeatedly sanctioned the channel and threatened to shut it down. It was accused in one instance of running allegedly incendiary reports on a 2011 prison riot. In another case, it was accused of sowing panic for running spots challenging the constitutionality of the government's decision to postpone the swearing in of Chavez, supposed to have occurred Jan. 10, due the cancer that ultimately killed him.
Globovision President Guillermo Zuloaga informed staff at a meeting Monday, naming the buyer as Juan Domingo Cordero, president of the insurance company La Vitalicia, the employees said. The company had no immediate comment but said it would issue a statement later in the day.
The Zuloaga family owns 80 percent of Globovision. The other 20 percent belonged to a banker but was expropriated years ago by Chavez.
The employee said Cordero is friendly with government officials such as National Assembly speaker Diosdado Cabello. He spoke on condition of anonymity for fear of losing his job.
In the meeting with employees, Zuloaga said that "politically, economically and legally" Globovision was no longer a viable business and had no access to dollars at preferential rates to buy equipment, as Cordero's business does.
The employee said the buyers had presented themselves as politically neutral.
"A lot of journalists were crying and surely more than one of them will have to go," the official said.
Zuloaga had been living outside of Venezuela since 2010 after a court ordered his arrest for allegedly illegally storing 24 automobiles at one of his homes.
It became the lone opposition channel in that year after RCTV was forced off cable and satellite networks.
Four private channels exist in Venezuela, all ostensibly neutral, while the government has four state-run channels and the regional news network Telesur. In print, two major national newspapers, El Nacional and El Universal, remain highly critical of the government.
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Frank Bajak on Twitter: http://twitter.com/fbajak
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Thursday, March 7, 2013
'Rhoda' Star Valerie Harper Diagnosed With Terminal Brain Cancer
Veteran TV actress Valerie Harper has been diagnosed with terminal brain cancer.
The Mary Tyler Moore Show actress 73, who played Rhoda Morgenstern in the hit series and its spin-off Rhoda, underwent a series of tests which showed she has leptomeningeal carcinomatosis, a condition that occurs when cancer cells spread into the fluid-filled membrane surrounding the brain.
Harper received the devastating news in January and has been told by doctors she has as little as three months to live.
Opening up about the diagnosis to People magazine, Harper says, "I don't think of dying. I think of being here now."
Harper previously battled lung cancer in 2009.
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