Wednesday, August 30, 2006

A centuries-old canine sexually-transmitted tumor

` At last, another strange science posting... but before I go into it, I would like to announce that I have discovered jpeg files of my pencil sketchbook (starting here) and can therefore continue posting them! Wooohooo!!!

` Anyway....

` According to an article in Nature, one dog or wolf that lived in Asia over 200 years ago has been linked to a disease called 'canine transmissible venereal tumor' or CTVT, that now affects dogs the world over.
` Unlike most cancers - which are merely caused by your own body's cells growing out of control - it is propagated by tumor cells that can actually spread while the animals have sex. After infection, tumors can develop on the dog's face and genitals, though usually they clear up in a few months.
` In the past, this disease was apparently more aggressive, unlike most cancers, and so figuring out why this is might help us to figure out how to make other cancers less lethal.

` Examining the DNA of the tumor cells of 16 unrelated dogs being treated in Italy, India and Kenya, Claudio Murgia and team at University College London have found a few things out. For one thing, virologist Robin Weiss says; "We can tell that the tumor didn't belong to the dog because it's genetically different from its host."
` So, the team analyzed over 400 dogs from 85 breeds and found that the cancer's DNA was most similar to modern wolves, and linked to certain Asian breeds. Judging by the number of mutations the cancer has sustained over the generations, as compared to wolves, it has been found that it is at least 200 years old.
"If it is any older than 250 years than it's the oldest cancer known to mankind," says Weiss. The work is published in Cell1.
` Looking at various frozen dog cancers of the past 30 years, collected from seven different countries, show that it was indeed once more aggressive. So, finding out why this had happened can help to cure human tumors, says Murgia.
` What happens today is that a new CTVT infection secretes a chemical that inhibits the dog's immune system from defending itself. A few months later, however, the dog fights it off. Sadly, the Tasmanian devil, a very inbred sort of marsupial, is being killed by contagious facial tumors - 90% are killed by it in some populations. Apparently, their immune systems have trouble recognizing the invader due to their limited gene pool (and thus, the cancer's).
` Humans, however, do not catch cancer from one another unless a transplanted organ contains one and their immune system isn't doing very well.

` Uhhhh.... yeah. And if that didn't do anything for you, I have a bonus post for you and more of my old sketches - which I'd totally forgotten that there were jpegs of - will be up and coming!


Galtron said...

Thank goodness that isn't something we have! Can you imagine? "WHOA! That bitch gave me face and genital cancer! I shoulda known she was up to something!!!"

I'm looking forward to the artwork.

S E E Quine said...

` Yeah... but at least they can easily fight it off because it is genetically different from the host. Otherwise it's not the easiest thing.

` I shall have glorious Dexters up at some point.

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