6936
Article 6936 (113 more) in sci.bio:
From: cccrsbc8@brolga.cc.uq.oz.au (cc rs)

Subject: Re: H2O2 as a disinfectant
Organization: Prentice Centre, University of Queensland
Date: Tue, 1 Dec 1992 12:17:07 GMT
Lines: 32

Hydrogen peroxide is a very strong oxidising agent
which can react with metal ions for example to form
reactive mutagen hydroxyl radicals HO-.  Normally
cells counteract the production of free radicals by
neutralising them with enzymes which for example
convert 2 x H2O2 to 2 x H2O + O2 (superoxide
dismutase).

the powerful oxidising effects of H2O2 also affect the
proteins in membranes - thus ion transporters and other
integral proteins are oxidised and become non-functional.
The overall effect is to kills the cells.

hydrogen peroxid mouthwash will turn all of the cells
around your gums white as it kills them.  Not all cells
will be killed - depending on the strength (30% will
--MORE--(68%)lose your sense of taste very quickly tho)

An example of the importance of the enzymes which remove
free radicals - hemolytic anemias where enzymes responsible for
the production of other molecules required by superoxide dismutase
are deficient.  Superoxide dismutase works less effectively,
the breakdown of red cells is enhanced --> anemia.

There is a growing body of literature on free radicals and their
role in mutagenesis, cancer, membrane disorders and metabolic
disease.

C.Zimitat
Biochemistry Dept, University of Queensland
Australia.   4072.

End of article 6936 (of 7055)--what next? [npq] Article 6943 (111 more) in sci.bio:
From: pburch@bcm.tmc.edu (Paula Burch)
Newsgroups: sci.med,sci.bio,sci.chem

Subject: Re: Tobacco, How Does It Cause Cancer ???
Date: 1 Dec 1992 17:42:45 GMT
Organization: Baylor College of Medicine, Houston, Tx
Lines: 15
Distribution: world
NNTP-Posting-Host: roc.mbcr.bcm.tmc.edu
Originator: pburch@roc.mbcr.bcm.tmc.edu


In article <70398@cup.portal.com>, mmm@cup.portal.com (Mark Robert Thorson) writ
es:
|> Mark Fulk's posting is very interesting, it implies that there is something
|> special about the tobacco plant which makes it carcinogenic.  Is tobacco
|> especially rich in benzo-a-pyrene?  If people smoked some other plant,
|> such as lettuce, would they be expected to get lung cancer at a much
|> lower rate?

Supposedly, smoking wheat or cocoa can also give you cancer. Wheat and cocoa 
are both commonly added to cigarettes for that much advertised "flavor." I 
expect that they probably lower the average carcinogenicity of the mix, 
--MORE--(96%)though.

Paula Burch
pburch@bcm.tmc.edu
End of article 6943 (of 7055)--what next? [npq] Article 6985 (109 more) in sci.bio:
Newsgroups: sci.med,sci.bio,sci.chem
From: polowin@chem.queensu.ca (Joel Polowin)

Subject: Re: Tobacco, How Does It Cause Cancer ???
Organization: Dept. of Chemistry, Queen's University
Date: Wed, 2 Dec 1992 15:56:24 GMT
Lines: 24

In article <1992Dec1.081414.1@bb1t.monsanto.com> bjgaed@bb1t.monsanto.com writes
:
>> Think again.  I don't have the decay chain of U-238 handy, but I know this
>> portion:  ...Rn-222 -> Po-218 -> Pb-214 -> Bi-214 -> Po-214 -> Pb-210 ->
>> Bi-210 -> Po-210 -> Pb-206       ^^^^^^                        ^^^^^^
>
>With the rather short half lives of Pb-214 (26.8 minutes) and Pb-210 
>(25 years) they are being destroyed much faster than they are being 
>produced.  Perhaps I am missing something here, so shoot me an e-mail 
>before I make too big a fool of myself.  

I'm afraid so...  Look at it from the time frame of the parent isotope,
with the really long half-life: The parent atom goes, and then all of the
daughter products sputter and bang almost instantaneously -- on that
relative time scale.  For every parent atom that decays, you get one
--MORE--(78%)decay from each of the daughter products in the chain.  Assuming that
your sample has acheived a steady state, the activity of each daughter
product is the same as the activity of the parent.  The relative    
concentrations will vary inversely with half-life, but the actual
activities will be the same.

Joel Polowin
polowin@silicon.chem.queensu.ca, polowin@chem.queensu.ca,
polowinj@qucdn.queensu.ca

End of article 6985 (of 7055)--what next? [npq] End of article 7008 (of 7055)--what next? [npq] 7008
Article 7008 (108 more) in sci.bio:
Newsgroups: sci.med,sci.bio,sci.chem
From: bjgaed@bb1t.monsanto.com

Subject: Re: Tobacco, How Does It Cause Cancer ???
Lines: 81
Organization: Monsanto Company, St. Louis, MO
Date: Thu, 3 Dec 1992 13:27:30 GMT

People...

Thanks to all the nice folks who sent me e-mail.  It has been a *long*
time since I dealt with nuclear chemistry kinetics.  (I'm really just
a potboiler. 8{). . . . )

My point in all of this was that people were speculating on mechanisms
of carcinogenisis, specifically by ingestion of polonium, without
looking very hard at the facts.  At about 100 ppm U-238 in fertilizer,
and about 0.1 ppm polonium in pitchblende that gives us about 1X10^-11
parts polonium in fertilizer. This is almost exactly the quoted 
permissible body burden of polonium (6.8X10^-11 g.)  Thus you would 
need to *completely* ingest 1 gram of fertilizer particles to achieve 
the maximum permissible body burden.           

--MORE--(29%)Whoever posted that number did not state the time period for that 
number.  Is it per day, per year, or per lifetime?

In any event it does not seem reasonable (to me, anyway) that *all* of 
the polonium in 1 gram of fertilizer particles could be vaporized, 
drawn into the lungs, and *completely* absorbed by the body in a year. 
A *lifetime* of smoking, maybe.  Then take into account the fact that 
maximum permissible body burdens are established *very* conservatively 
to be at a *zero effect level*.

Without *facts* such as maximum permissible body burden over a 
specific period of time, assays of the amount of fertilizer remaining 
on processed tobacco, a rational model for transfer of the volatile 
components of fertilizer particles into the body, actual *average* 
amounts of U-238 in fertilizers applied to tobacco fields, some idea 
of the amounts of U-238 in fertilizers applied to Chinese tobacco 
fields, and on and on ..., statements such as "...plausible 
explanation for the difference in cancer rates between Chinese and 
American smokers..." (or words to that effect) are *just plain 
irresponsible*.

Such things lead to all kinds of panic on the part of the public.  
Such things are often used by interest groups such as the tobacco 
--MORE--(57%)industry to claim that it isn't their product that causes cancer, it's 
the fertilizer.  When the public hears a scientist making those kind 
of statements they get into the mindset that "It's radioactive, 
therefore it causes cancer, therefore we must expend any amount of 
resources to eliminate that risk."  As I have said here many times, we 
have to put some rational, scientific numbers on those risks before we 
start expending resources on eliminating them.  Unless you live in a 
world with unlimited resources (I don't) you had better apply 
resources first and foremost to the highest areas of risk if you want 
to improve public health.

In another thread someone speculated that asbestos fibers intercalate 
between base pairs in DNA.  Asbestos fibers can be seen with a 
light microscope.  Nothing that big could even get near DNA.  The 
fiber is orders of magnitude larger than the DNA strand.

That's what I meant when I said "Think before you post."  Think about 
how the public (this is a public newsgroup, and is read by all kinds 
of people) will take your statement.  Legitimate requests for 
information are fine; that's how we all learn.  Unsupported and 
unreasonable statements on epidemiology or toxicology are 
irresponsible.

--MORE--(85%)There is an old sea ditty that goes:

"When in danger or in doubt,
        Port your helm and come about."

This is would be well applied to all of us.  If you are unsure, take 
the prudent course.  Find out first, if you can.  Clarify the 
situation before taking action.  Otherwise, you get the Navy sailor's 
view of how officers make decisions:

"When in danger or in doubt,
        Run in circles, scream and shout."



--Electric Monk            (Bruce Gaede); 
                            e-mail: bjgaed@ccmail.monsanto.com

"...and then time started seriously to pass."
--Douglas Adams, _Dirk Gently's Holistic Detective Agency_
End of article 7008 (of 7055)--what next? [npq] 7031
Article 7031 (107 more) in sci.bio:
Newsgroups: sci.med,sci.bio,sci.chem
From: small@bcstec.ca.boeing.com (Peter Small)

Subject: Re: Tobacco, How Does It Cause Cancer ???
Organization: Boeing
Date: Thu, 3 Dec 1992 18:03:53 GMT
Lines: 22

In article <1fj6g9INNfn7@gazette.bcm.tmc.edu> pburch@bcm.tmc.edu (Paula Burch) w
rites:
>
>I've heard that it's possible to buy pre-rolled "all natural" cigarettes 
>which contain nothing but tobacco, but I'm stymied as to where you'd go to 
>find them. The usual source for "all natural" products, the health food 
>store, surely wouldn't...or would they?

You can find them in Tobacco shops; they're called American Spirit...

The tobacco companies in the US are not required to report what tha add to the
tobacco in their cigarettes.  I have read that when Marlboros are sold in
France the label says 90% tobacco, with a few other flavoring agents (10%!).

In China, where they smoke only tobacco in their cigarettes, there is a much
--MORE--(75%)less incidence on lung cancer among smokers even though the Chinese are in
general heavy smokers.  Who knows what American cigarette companies are adding 
to their cigarettes, which may be major contributors to lung cancer.
-- 
-----------------------------|**************************************************
-- small@bcstec.ca.boeing.com|
-- uunet!bcstec!small        |
-----------------------------|
End of article 7031 (of 7055)--what next? [npq] 