Humans energy metabolism

Carnitine is a vitamin-like quaternary ammonium salt, playing an important role in the human energy metabolism by facilitating the transport of long-chained fatty acids across the mitochondrial membranes. An easy, fast, and convenient procedure for the separation of the enantiomers of carnitine and 0-acylcarnitines has been reported on a lab-made teicoplanin-containing CSP [61]. The enantioresolution of carnitine and acetyl carnitine was enhanced when tested on a TAG CSP, prepared in an identical way [45]. Higher a values were reached also in the case of A-40,926 CSP [41]. 

AH values for various food substances and their application to human energy metabolism are discussed later in this chapter. 

Coward, W. A., Prentice, A. M., Murgatroyd, P. R., Davies, H. L., Cole, T. J., Sawyer, M., Goldberg, G. R., Halliday, D., and Macnamara, J. P. (1984). Measurement of COj and water production rates in man using H, -labelled H2O comparison between calorimeter and isotope values. In Human Energy Metabolism Physical Activity and Energy Expenditure Measurements in Epidemiological Researdi Based Upon Direct and Indirect Calorimetry (A. J. H. van Es, ed.), pp. 126-128. EURO-NUT, The Netherlands. 

Figure 2. Force generation and energy metabolism in human quadriceps femoris muscle stimulated intermittently at 20 Hz, with 1.6 sec tetani with 1.6 sec rest periods between tetani. The upper panel shows force, ATP turnover rate, and pH the middle panel, the concentrations of PCr, P and lactate and the lower panel, ATP, ADP, IMP, H, and calculated H2PO4. From Hultman et al. (1990), with permission from Human Kinetics Publishers.

Feron et al. (1990) have concluded that, in general, adjustment for differences in body size between experimental animals and humans should be based on caloric requirement (energy metabolism) as this was considered to be both scientifically sound and of practical significance. 

CFS patients and is related to autonomic dysfunction. In a separate rat study, Giannesini et al. used citrulline malate (CM) to treat asthenia and found that the supplementation prevented the basal PCr/ATP ratio reduction and normalized the pHi time-course during muscular activ-ity. They conclude that CM supplementation corrects the impaired control of oxidative function and has protective effect on basal energy metabolism. The data from either human or animal studies provide a potential approach to therapy. 

In practice, animal calorimetry is quite complicated because of the inherent difficulty of accurate heat measurements, uncertainties about the amount of food stored, and the necessity of corrections for AHc of the waste products. However, the measurement of energy metabolism has been of considerable importance in nutrition and medicine. Indirect methods of calorime-tery have been developed for use in measuring the basal metabolic rate of humans. For a good discussion see White et al.u... 

Levine SR, Helpern JA, Welch KM, Vande Linde AM, Sawaya KL, Brown EE, Ramadan NM, Deveshwar RK, Ordidge RJ (1992) Human focal cerebral ischemia evaluation of brain pH and energy metabolism with P-31 NMR spectroscopy. Radiology 185 537-544... 

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