題名には必ず「阿修羅さんへ」と記述してください。
掲示板,ＭＬを含むこのサイトすべての
一切の引用、転載、リンクを許可いたします。確認メールは不要です。
引用元リンクを表示してください。
投稿者 佐藤雅彦 日時 2001 年 1 月 24 日 08:08:24:
「狂牛病」病原体は宇宙から飛来した、だって?!
●「狂牛病」（BSE：ウシ海綿状脳症）の病原体と発症メカニズム
については、いまだに不明な部分が多い。いちおう「プリオン」と
いう感染性タンパク質が「病原体」だということになっていますが、
十数年前、この説を提唱した米国の生化学者は、キ■■イ呼ば
わりされていたものです。
●謎多き「狂牛病」の突発出現（エマージング）を説明する仮説
として、ついに「狂牛病プリオン宇宙飛来説」が登場しました。
●とりあえず近代科学ってのは「怪力乱心を語らず」という姿勢
をモットーにしてきたわけですが、それを簡単に「天から降ってき
た」ことにしてしまって、いいんですかねぇ？ 狂牛病って、蛋白
工学が本格化した時期にタイミングよく登場したんですが、実験
的に生み出され故意または事故によって環境中に放出されたと
いうシナリオのほうが、よほど無理がないと思うんですが……。
「天から降ってきた」説が出てくるんなら、生物兵器説や、神の怒り
説が出てきたって全然おかしくないでしょうな。エイズのときがそう
だった。
●ＨＩＶも、いわゆる「人食いバクテリア」も、病原性大腸菌0-157も
９０年代にインドやペルー沖に登場した新型コレラ菌も、あるいは
変異型のエボラウイルスなんかもそうですが、７０年代以降に顕著
になった各種の突発出現病原体って、人為操作によって生じた可
能性が高いんですけど、にもかかわらず科学者たちは相当理不尽
な“理屈”をつけて「自然発生した」ことにしようとする傾向が強いの
ですよ。（このあたりの不自然さについては、８９年にロックフェラー大
学やイェール大学のウイルス学者や米軍生物兵器担当者が集って
“突発出現ウイルス”の概念を練り上げた研究集会の記録である
『突発出現ウイルス』［S・モース編、海鳴社］が絶対的な必読書です。
ちなみに日本の感染症研究の――アメリカ軍陣医学のひも付き――
研究者どもは、“突発出現ウイルス”という概念とその発生メカニズム
の公認シナリオづくりの事実に目をむけようとせず、数年後にWHOで
“突発出現ウイルス”概念が公認された時点からのことしか語って
いない点が、なんともイカガわしいのです。）
■■■■@■■■.■■■■■■■■■■■■■■■■■■■
Small Steps, Big Questions
Mad Cow Research Steady, But Slow Due to Diseases Bizarre Form
By Amanda Onion
http://abcnews.go.com/sections/scitech/DailyNews/madcowresearch010119.html
Jan. 22 Mad cow disease is so terrifying and perplexing that some
researchers have begun to believe it could have alien origins.
STORY HIGHLIGHTS
Infectious, Warped Proteins Solutions From Car Paint? New Ways to
Diagnose The Mad Cow Holy Grail
Two astronomy and mathematics professors in England announced last month
that cows in England and Wales may have picked up the disease after
eating grass laced with a sprinkling of interstellar dust. The dust, the
scientists proposed, fell as the Earth was bombarded by comets which
hosted infectious, extraterrestrial matter.
The notion may seem outlandish (and many scientists think it is), but
research shows the disease, itself, is outlandish. And its bizarre
nature has stumped many efforts to find effective screening tools and
treatment.
"When you're trying to design drugs, it's especially difficult when you
don't fully understand the nature of the infectious agent," says Byron
Caughey, a biochemist at the Rocky Mountain Laboratory branch of the
National Institutes of Health.
MAD COW MENACE
LAST WEEK:
Blood Donor Bans: Protecting The U.S. Blood Supply
Food, Vaccines and Supplements: How Vulnerable Is America?
TODAY:
Searching For Answers
Infectious, Warped Proteins
To defeat the disease, however, scientists must understand its nature.
So researchers across the U.S. and Europe are furiously studying mad cow
and its infectious agent's puzzling behavior to try and come up with
treatments as well as better screening tests for the disease.
Creuztfeld-Jacob disease, one of a group of terrible animal and human
diseases called Transmissible Spongiform Encephalo
pathies (TSE), has
been recognized as a rare human scourge for decades. But a new variant
of the disease emerged in Great Britain in the late 1980s which
scientists believe is related to eating beef infected with BSE, or mad
cow disease.
Research so far suggests mad cow disease and its cousins, which attack
the brain and slowly transform it into a spongy mass of useless tissue,
are caused by a most unlikely agent a protein. These proteins, known
as prions, are nearly normal, except that rather than folding into an
intricate, orderly pattern, the strings of these proteins are refolded
into tough and toxic deposits.
These abnormal prions infect the body by binding with normal prion
proteins and triggering them to take on the corrupted structure of the
rogue proteins. The body's weapons, known as protease enzymes, which
chop up and dispose of unwanted proteins, are rendered useless against
the transformed prion proteins.
Heat, a common tool for destroying infectious agents, has also been
shown to be less effective against the prion. Paul Brown, a prion
researcher at the Bethesda, Md., branch of the National Institutes of
Health, has exposed rogue prion proteins to temperatures higher than
1,000 degrees Fahrenheit and found some emerged unscathed.
"That's just unheard of," Brown says.
Particularly puzzling to scientists is how a protein, which contains no
genetic information and is usually just a messenger of genetic codes,
can direct its own propagation. By understanding how it influences other
proteins, scientists hope to find a way to stop its ability to infect.
Solutions From Car Paint?
Last year British researchers located compounds that can stop rogue
prions from converting normal prion proteins in animals infected by
scrapie, the oldest known TSE disease, which infects sheep and goats.
And recently, Caughey and his colleagues at the Rocky Mountain Lab in
Montana have zeroed in on other compounds, similar to ones used as
pigments in car paints, that have a similar effect.
But there's a glitch: the compounds are only effective if administered
at the very beginning of infection. This is a big problem since the
symptoms of mad cow-related diseases can take between 10-40 years to
surface.
Caughey thinks the trick lies in finding compounds that can enter the
brain where defective prions tend to congregate.
"We need to find compounds that can cross the barrier into the brain so
they can do their good deeds there," he says.
Since there is concern that mad cow and its related diseases can be
transmitted not only through meat consumption but also through blood
supplies, researchers at University Hospital in Zurich, Switzerland, are
refining a prion-fighting agent that might help disinfect blood tainted
by the disease. The agent, a common blood component, attaches to rogue
prions, but not to harmless ones, the scientists
found.
But some argue it's pointless to find ways of fighting infectious prions
without a simple, affordable method to test for them.
New Ways to Diagnose
"Therapies without a screening test are not worthwhile," says Robert B.
Peterson, a professor of pathology at Case Western Reserve University in
Ohio. "By the time you offer the treatment, you can only stabilize, not
eradicate the disease."
Peterson recently took on the role as chief scientific adviser to a
two-month-old company formed with the sole focus of finding an effective
screening test for TSE diseases. Prion Developmental Laboratories, based
in Maryland, has recruited the likes of Peterson as well as the main
developer of the AIDS screening test, Robert Gallo of the University of
Maryland.
Peterson points out the only way to diagnose mad cow disease or its
human equivalent now is by examining brain samples after death at a cost
of $50-$100 per test. The company's scientists are looking for ways to
amplify the signals of rogue protein prions so that they might be
detected while still at low levels in the blood.
A few screening agents have already emerged that might prove effective
at doing just that. Researchers at Caprion Pharmaceuticals in Montreal,
say they have developed unique antibodies that can tell harmless protein
prions from defective ones. The antibodies have already been tested in
infected mice, hamsters and sheep.
In Ames, Iowa, Mary Jo Schmerr of the National Animals Disease Center,
has produced another hopeful prion detector. Her antibodies, which she
developed in lab rabbits, have spotted rogue proteins in elk and deer
infected with scrapie.
"With further development," Schmerr writes in an e-mail, "this has good
potential for use as screening for detecting TSE's in animals and
humans."
The Mad Cow Holy Grail
Despite such recent advances, it's unlikely any highly effective test or
treatment will be found until scientists gain a better handle on the
biggest question still looming over all investigations of the disease:
whether defective proteins, alone, spread the infection.
"Most feel the prion hypothesis is true that the protein, itself, is
infectious," says David Harris, a prion researcher at Washington
University. "But everyone also recognizes that it's still hard to
definitively rule out other factors, such as a virus or bacterium."
So far scientists have not found any virus or bacterium that helps
spread mad cow and related diseases. The Holy Grail, Harris explains,
will be to somehow manipulate normal prion proteins in the laboratory to
take on the nature of the deformed, infectious prions.
Only then could scientists prove this puzzling, almost alien-like
protein is acting alone.
題名には必ず「阿修羅さんへ」と記述してください。