Guest guest Posted May 21, 2005 Report Share Posted May 21, 2005 Hi Al: Is the following passage perhaps the most important in the bone health study you referenced below? " CR: An additional six rats (28 mo old) were CR at the NIA as described by Turturro et al. (40). As per NIA methods, beginning at 14 wk of age, CR animals were introduced to a reduced caloric intake (60% of the calories of the mean food intake of the ad libitum group), while they maintained nutrition equivalent to the ad libitum group " . Now fourteen weeks of age for the introduction of CR in mice does seem very early if one is hoping to draw conclusions for the effects of CR on humans. Mice live three or four years. Humans live 70 to 100 years. So the ratio human/mouse lifespan is roughly 25:1. (Please correct me if I have this wrong). So fourteen weeks of age in mice is the equivalent of about 6.7 years in humans. This is well after weaning, but before puberty and a long time before full growth is attained. For sure this study may have great relevance to humans put on CR at age seven. But I would think it would have little relevance to those of us who started CRON after age 20. Perhaps it is useful input for those thinking of inflicting CR on their kids too early? Rodney. --- In , Al Pater <old542000@y...> wrote: > Hi All, > > See the pdf-available below. It has been is somewhat dated, but the bad details of > CR's affect on bone health may be worth presentation of the details. > > LaMothe JM, Hepple RT, Zernicke RF. > Selected contribution: Bone adaptation with aging and long-term caloric restriction > in Fischer 344 x Brown-Norway F1-hybrid rats. > J Appl Physiol. 2003 Oct;95(4):1739-45. Epub 2003 Jun 13. > PMID: 12807893 > > http://www.ncbi.nlm.nih.gov/entrez/query.fcgi? cmd=Retrieve & db=pubmed & dopt=Abstract & list_uids=12807893 & query_hl=26 > > http://jap.physiology.org/cgi/content/full/95/4/1739/TBL4 > > ... Table 4. Rat L6 vertebral mechanics > -------------------------------------------------------------------- ------------ > Months-------8 28 28-CR 36 > -------------------------------------------------------------------- ------------ > Load at proportional limit, N 341±82 352±88 240±23*** 300±27 > Load at proportional limit/mass, N/g 0.78±0.22 0.70±0.17 0.74±0.08 0.60±0.08 > Stress at proportional limit, MPa 16.6±3.9 16.8±3.9 12.9±2.7 14.9±2.2 > Strain at proportional limit, % 26.1±3.9 35.6±10.2 30.7±2.3 26.5±3.0 > Maximal load, N 404±94 399±118 261±17*** 342±48 > Maximal load/mass, N/g 1.26±0.28 0.80±0.23* 0.80±0.06* 0.69±0.11* > Stress at maximal load, MPa 18.6±4.5 18.2±4.2 13.5±2.6 16.3±3.4 > Strain at maximal load, % 29.1±4.3 36.8±9.1 32.6±1.9 28.2±2.4 > Stiffness, kN/mm 1.41±0.59 1.31±0.98 0.78±0.28 1.18±0.30 > Stiffness/mass, kN·mm-1·g-1 3.23±1.48 2.64±1.95 2.42±0.86 2.36±0.59 > Apparent elastic modulus, MPa 330±129 308±210 237±53 296±90 > -------------------------------------------------------------------- ------------ > Values are means±SD. *Significantly different from 8-mo mean (P </= 0.05). > **Significantly different from 36-mo and 28-mo mean (P </= 0.05). ... > > Al Pater, PhD; email: old542000@y... > > __________________________________________________ > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 22, 2005 Report Share Posted May 22, 2005 Thanks Al. I have emailed a couple of websites asking them at what age mice are full-grown. If I get an answer I will post it. Rodney. > > > > Mice live three or four years. Humans live 70 to 100 years. So the > > ratio human/mouse lifespan is roughly 25:1. (Please correct me if I > > have this wrong). So fourteen weeks of age in mice is the equivalent > > of about 6.7 years in humans. This is well after weaning, but before > > puberty and a long time before full growth is attained. > > > > For sure this study may have great relevance to humans put on CR at > > age seven. But I would think it would have little relevance to those > > of us who started CRON after age 20. > > > > Hi All, > > Mice develop much more quickly than humans for their growth to puberty. Only about > a month should do it, I seem to recall. > > Al Pater, PhD; email: old542000@y... > > > > __________________________________ > Mobile > Take with you! Check email on your mobile phone. > http://mobile./learn/mail Quote Link to comment Share on other sites More sharing options...
Guest guest Posted May 22, 2005 Report Share Posted May 22, 2005 Hi Al: So here is the answer: " A healthy, well fed mouse is generally considered to have reached its adult size by 12 weeks, although internally they may still do a little growing for a couple more weeks, but it will not be noticeable " . So perhaps that is why the study started with 14-weeks old mice. Hmmmmm. So that makes those data in that study possibly very relevant to us. Thank you for correcting me on that. Rodney. > > > > > > Mice live three or four years. Humans live 70 to 100 years. So > the > > > ratio human/mouse lifespan is roughly 25:1. (Please correct me > if I > > > have this wrong). So fourteen weeks of age in mice is the > equivalent > > > of about 6.7 years in humans. This is well after weaning, but > before > > > puberty and a long time before full growth is attained. > > > > > > For sure this study may have great relevance to humans put on CR > at > > > age seven. But I would think it would have little relevance to > those > > > of us who started CRON after age 20. > > > > > > > Hi All, > > > > Mice develop much more quickly than humans for their growth to > puberty. Only about > > a month should do it, I seem to recall. > > > > Al Pater, PhD; email: old542000@y... > > > > > > > > __________________________________ > > Mobile > > Take with you! Check email on your mobile phone. > > http://mobile./learn/mail Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.