X-Message-Number: 12807
Date: Sat, 20 Nov 1999 09:01:54 -0800 (PST)
From: Doug Skrecky <>
Subject: Optimism and Realism

In Message #12796 "George Smith" <> wrote:

>I applaud Doug's efforts.  I will be curious to hear what he
>and other experts have to say on the Italian mice longevity
>breakthrough:
>
  I have not had the opportunity to read the
latest issue of Nature, so I can not comment
on the details of the experiments. However with
an average lifespan of 973 days (or 32.4 months),
the modified mice did not out-live control mice
from a variety of strains used in other
experiments. I would suggest that a certain amount
of skepticism would be in order here. All this
experiment may prove is that the treatment helps
prevent the life shortening effect of poor animal
care.
  The game of over-stating your results is an
old one, which has been used many times in the
past. For example Roy Walford increased the mean
lifespan of C57BL/6J mice from 24.9 to 29.0 months
by restricting calories. (Science 215(12) 1415-1418
March 1982) Looks good, until you realize a previous
experiment by Walford found mean lifespan of one
group of control C57BL/6J mice was 32.8 months,
while for the restricted group it was 28.8 months.
(Expt Gerontology 15: 237-258 1980)
  For those who are interested, C57BL/6J mice die
mostly from lymphoma cancer. The survival enhancing
effect of CR in this strain is dependant on
housing temperature. Higher housing temperature blocks
both the induction of torpor by CR, and
largely eliminates its benefit on mean lifespan.
(Mechanisms of Ageing and Development 92: 67-82 1996) The 
anti-lymphoma effect of reduced body temperature is a key 
determining factor in C57BL/6J lifespan.
  For the record the rodent chow used by scientists does not resemble
either the natural foods the rodents might encounter, or chow 
available in pet food stores. Lab chow is an artificial, 
phytochemical striped, potassium reduced, ultra high glycemic 
index diet. There are usually no whole seeds for example, and the 
main source of calories is either table sugar, or corn starch. 
Insulin resistance, enhanced tumor growth, and renal
failure are avoidible side effects of lab chow.

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12807