X-Message-Number: 10019
Date: Thu, 9 Jul 1998 02:47:51 -0700 (PDT)
From: Doug Skrecky <>
Subject: caloric restriction, temperature and cancer 

  Koizumi A.  Wada Y.  Tuskada M.  Kayo T.  Naruse M.  Horiuchi K.  Mogi T. 
  Yoshioka M.  Sasaki M.  Miyamaura Y.  Abe T.  Ohtomo K.  Walford RL.
  Department of Hygiene, Akita University School of Medicine, Japan.
  A tumor preventive effect
  of dietary restriction is antagonized by a high housing temperature through
  deprivation of torpor.
  Mechanisms of Ageing & Development.  92(1):67-82, 1996 Nov 29.
  Energy restriction (ER) has proven to be the only effective
  means of retarding aging in mice. The mechanisms of multiplicity of
  effects of ER on aging remain, however, fragmentary. ER
  induces daily torpor, the induction of which is reduced by increasing the
  ambient temperature to 30 degrees C. The effects of
  preventing hypothermia in ER animals were studied in terms of the expected
  consequences of ER on survival, disease pattern and a number of physiological
  parameters in autoimmune prone MRL/lpr mice and lymphoma prone C57BL, 6 mice.
  The results demonstrate that torpor plays a crucial role in the prevention of
  lymphoma development but does not have an affect on other aspects of ER, such
  as prevention of autoimmune diseases.

 Additional data added here by the poster:

   Mortality data for the autoimmune MRL strain and the lymphoma prone
 C57BL strain of mice are as follows: (data derived from table 1)

                     Survival (days)     Percentage alive
                     75%   50%   25%       at 1300 days
 MRL     Control    167   205   255            0%
         Cntl/30C   170   213   230            0
         CR         217   269   519            8
         CR/30C     201   284   340            0

 C57BL   Control    559   778   880            0
         CR         941  1143  1264           19
         CR/30C     739   810  1049            0

   Storage temperature had no effect on early autoimmune related MRL
 mortality, which was mostly cerebral hemorrhage, subarachnoid hemorrhage
 and rupture of aortic aneurysms. However later mortality was reduced in
 calorie restricted MRL mice stored at room temperature as opposed to
 those stored at 30C. Presumably this is due to the anticancer effect of
 CR induced hyperthermia, which is antagonized by elevated storage
   Storage at 30C largely reversed the early antilymphoma effect of CR in
 C57BL mice, reducing the 47% increase in the 50% survival found in CR
 mice to just 4% for the CR/30C group.
   The survival for control C57BL mice varies dramatically from experiment
 to experiment. In one control group from (Experimental Gerontology 15:
 237-258 1980) the 50% survival was about 960 days, which is roughly
 midway between the CR and CR/30C groups in the present experiment.
 Variations in temperature regulation of the laboratory may account for
 some of these differences.

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