Metabolic interrelationships

Figure 27-1. Metabolic interrelationships between adipose tissue, the liver, and extrahepatic tissues. In extrahepatic tissues such as heart, metabolic fuels are oxidized in the following order of preference (1) ketone bodies, (2) fatty acids, (3) glucose. (LPL, lipoprotein lipase FFA, free fatty acids VLDL, very low density lipoproteins.)...

The metabolism of cholesterol in mammals is extremely complex. A summary sketch (fig. 20.24) helps to draw the major metabolic interrelationships together. Cholesterol is biosynthesized from acetate largely in the liver (fig. 20.24a) or taken in through the diet (fig. 20.24b). From the intestine, dietary cholesterol is secreted into the plasma mainly as a component of chylomicrons. The triacylglycerol components of chylomicrons are quickly degraded by lipoprotein lipase, and the remnant particles are removed by the liver. Apoproteins and lipid components of the chylomicrons and remnants appear to exchange with HDL. Cholesterol made in the liver (fig. 20.24a) has several alternative fates. It can be (1) secreted into plasma as a component of VLDL,... 

Harris, R. A., and Crabb, D. W. 1997. Metabolic interrelationships. In Textbookof Biochemistry with Clinical Correlations (pp. 525 - 562), edited by T. M. Devlin. Wiley-Liss. 

Fig. 3. Metabolic interrelationships of lipoproteins (lipoprotein abbreviations are as given in Table I). LpL, Lipoprotein lipase LCAT, lecithin-cholesterol acyltransferase HL, hepatic lipase CETP, cholesteryl ester transfer protein. Solid lines represent interconversion of particles regular dashed lines represent movement of cholesterol irregular dashed lines represent transfer of lipids mediated by CETP.

Fig. 2. Metabolic interrelationships between free fatty acid and glucose metabolism. (Source Randle et al., 1963.)...

The metabolic interrelationship between mitochondrial carbamoyl phosphate synthesis to urea formation and to cytosolic carbamoyl phosphate channeled into pyrimidine biosynthesis. In ornithine transcarbamoyiase (OTC) deficiency, mitochondrial carbamoyl phosphate diffuses into the cytosol and stimulates pyrimidine biosynthesis, leading to orotidinuria. Administration of allopurinol augments orotidinuria by increasing the flux in the pyrimidine biosynthetic pathway. CPS = Carbamoyl phosphate synthase, AT = aspartate transcarbamoyiase, D = dihydroorotase, DH = dihydroorotate dehydrogenase, OPRT = orotate phosphoribosyltransferase, XO = xanthine oxida.se,... 

M25. Mills, C. F., Metabolic interrelationships in the utilization of trace elements. Proc. Nutr. Soc. Engl. Scot. 23, 38-45 (1964). 

In the present overview, the uptake and metabolic conversion of glucose, fatty acids, and amino acids in mammalian cells have been discussed. Only the main metabolic routes and mechanisms underlying the regulation of enzymes and transport proteins controlling the rate-limiting steps are described. It should be noted that at some points, details are left out and metabolic interrelationships are simplified for the sake of clarity. For details the reader is referred to the original publications and modern textbooks of biochemistry. 

Levander OA. 1972. Metabolic interrelationships and adaptations in selenium toxicity. Ann NY Acad Sci 192 181-192. 

Levander OA. 1977. Metabolic interrelationships between arsenic and selenium. Environ Health Perspect 19 159-164. 

For many years it was thought that the placenta acted as an independent endocrine gland during pregnancy, and only comparatively recently was it realized that the fetus is also considerably involved in steroid production and catabolism, certain mechanisms for the metabolism of steroids being present in the fetus and not in the placenta, and vice versa. The complex steroid metabolic interrelationships which exist between the fetus, the placenta, the maternal endocrine glands and the mother as a whole have been discussed in a previous review (M16) and will be covered only insofar as they affect an understanding of the situation in early infancy. 

LI. Lahiri, S., and Banerjee, S., Metabolic interrelationship between ascorbic acid and pteroylglutamic acid. Proc. Soc. Exptl. Biol. Med. 91, 545-548 (1956). 

The distribution of ingested selenium in organs and tissues depends on its chemical form. Various metabolic interrelationships between both inorganic and organic forms of selenium are illustrated in Figure 7.5, while the relationship of ingested selenium to tissue selenium is illustrated in Figure 7.6 (Burk 1986). Mammals (includ-... 

Fig. 7.5 Metabolic interrelationships between inorganic and organic forms of selenium.

The following scheme C2] shows the metabolic Interrelationships between the 3B-ecdysterolds and their 3a-eplmers... 

The traditional p/s ratio and now the n-6/n-3 PUFA ratio may be of little value because they fail to recognize the multiple effects of dietary PUFA and their metabolic interrelationships. In a multivariate system, attempts to describe a ratio of two variables have little meaning and are an inappropriate description of a mixture of fatty acids having a multiplicity of biosynthetic effects. These values should therefore be considered only as possible targets. It should be no longer valid to base dietary recommendations on the attainment of plasma... 

Much more information is needed about the metabolic characteristics of the fat-storing cells and about the metabolic interrelationships between these cells and parenchymal cells. The mechanism whereby retinol is transferred between these two types of cells requires exploration. This mechanism may involve one of the known retinoid-binding proteins or a different protein present in the intercellular space. Studies in the authors laboratory (M. Kato and D. S. Goodman, unpublished observations) using immunohistochemical methods and antibodies specific for CRBP have shown that CRBP is concentrated in the fatstoring cells. Information is needed about the potential enzymatic capability of... 

In a more recent paper, Svennerholm s group (Martensson et al. 1966) has reviewed the subject and has interpreted the available data on the metabolic interrelationship between cerebrosides and sulfatides according to the following scheme ... 

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