Metabolism scaling

Bergmann (1847) hrst noted that metabolic rate in mammals appeared to scale with mass to a 2/3 power. Rubner (1883) observed that heat production appeared to be more closely correlated with surface area than with mass, positing the widely cited Rubner s rule or surface law. Huxley (1932) advocated htting metabolic rate to a power function of mass, and based on the most extensive empirical analysis to date, Kleiber (1932) concluded that the exponent was 3/4. By mid-century we had the 3/4 rule. Surface area explanations of metabolic scaling were abandoned. For one thing, they required a 2/3 exponent (representing the linear dimension squared) that did not ht the data. In addition, metabolic rate scaled to body mass by a similar power function in ectotherms, for which the metabolic replacement of surface-mediated heat loss was not relevant. 

Clarke, A. and Fraser, K. P. (2004). Why does metabolism scale with temperature Functional Ecology, 18, 243-51. 

Table 1. OLS and RMA estimates of efficiency (k and ME for 3/4 and 2/3 metabolic scaling laws in relation to steers of 120 kg LW.

Often heat removal causes design problems for scale-up. Mechanical agitation coupled with a metabolic heat from the growing biomass... 

Hunger-stein, m. salt-pan scale (sulfates of calcium and sodium, etc.), -stoffwechsel, m. starvation metabolism. -tod,w. (death from) starvation. 

Salz-schicht, /. layer of salt, -schmelze,/. salt melt, fused salt, -see, /. salt lake, -siede-pfanne, /. salt pan. -sieder, m. salt boiler, salt maker, -siederei, /. salt making salt works, -sole, -soole, f. brine, salt water salt spring, -speck, m. bacon, -stein, m. boiler scale rock salt, -stoffwechsel, m. salt metabolism, -ton, m. salt clay, saliferous clay. -wa(a)ge,/. brine gage, salinometer. 

Valentini, R., Scarascia Mugnozza, G.E., De Agnelis, P. and Matteucci, G. 1995 Coupling water and carbon metabolism of natural vegetation at integrated time and space scales. Agricultural and Forest Meteorology 73 297-306. 

The samples of l,6-T2-DBpD and l,6-T2-2,3,7,8-Cl4-DBpD are useful in metabolism and mode of action studies. For example, when incubated with rabbit liver microsomes, l,6-T.>-DBpD is extensively metabolized to polar product(s) but only when these preparations are fortified with reduced nicotinamide-adenine dinucleotide phosphate. Under the same conditions l,6-T2-2,3,7,8-Cl4-DBpD is completely resistant to metabolic attack. In some types of studies, a higher specific activity possibly is desirable i.e., >1 Ci/mmole), and this can be achieved, with the methodology already developed, by using larger amounts of tritium gas or working on a larger synthetic scale so that it is not necessary to add unlabeled materials to assist in crystallization steps where a certain minimum amount of compound is necessary. 

West GB, Woodruff WH, Brown JH. Allometric scaling of metabolic rate from molecules and mitochondria to cells and mammals. Proc Natl Acad Sci USA 2002 99 Suppl 1 2473-8. 

Famili I, Forster J, Nielsen J, Palsson BO. Saccharomyces cerevisiae phenotypes can be predicted by using constraint-based analysis of a genome-scale reconstructed metabolic network. Proc Natl Acad Sci USA 2003 100 13134-9. 

Schilling CH, Covert MW, Famili I, Church GM, Edwards JS, Palsson BO. Genome-scale metabolic model of Helicobacter pylori 26695. J Bacteriol 2002 184 4582-93. 

Sato et al. (1991) expanded their earlier PBPK model to account for differences in body weight, body fat content, and sex and applied it to predicting the effect of these factors on trichloroethylene metabolism and excretion. Their model consisted of seven compartments (lung, vessel rich tissue, vessel poor tissue, muscle, fat tissue, gastrointestinal system, and hepatic system) and made various assumptions about the metabolic pathways considered. First-order Michaelis-Menten kinetics were assumed for simplicity, and the first metabolic product was assumed to be chloral hydrate, which was then converted to TCA and trichloroethanol. Further assumptions were that metabolism was limited to the hepatic compartment and that tissue and organ volumes were related to body weight. The metabolic parameters, (the scaling constant for the maximum rate of metabolism) and (the Michaelis constant), were those determined for trichloroethylene in a study by Koizumi (1989) and are presented in Table 2-3. 

An overall osteoprotective effect is associated with soy diets, the major active component being the isoflavones although the contribution (if any) of soy protein has to be clarified. The spine, rather than the femur, appears to be the most consistently protected bone site. The average daily intake in Japanese women is around 50 mg/day and appears to be sufficient to have a long-term protective effect on the spine. In non-Asian, postmenopausal women, the demonstrated effective dose is 80-90 mg/day. In future clinical studies, investigating the effect of isoflavones on bone metabolism, larger scale, randomized, controlled, intervention trials for longer time periods (1-3 years) will be necessary with a standardized source of soy protein/isoflavones and... 

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