Meat metabolic activation

Although pyridoxine, pyridoxamine, and pyridoxal are different forms of vitamin Be, pyridoxal-5 -phosphate is the metabolically active form, acting as a cofactor in different reactions involving amino acids, mainly, transamination. Good food sources of this vitamin include meat, poultry, fruit, potatoes, and some vegetables. From the different forms in which... 

A second important difference between mitochondrial and peroxisomal fi oxidation in mammals is in the specificity for fatty acyl-CoAs the peroxisomal system is much more active on very-long-chain fatty acids such as hexacosanoic acid (26 0) and on branched-chain fatty acids such as phytanic acid and pristanic acid (see Fig. 17-17). These less-common fatty acids are obtained in the diet from dairy products, the fat of ruminant animals, meat, and fish. Their catabolism in the peroxisome involves several auxiliary enzymes unique to this organelle. The inability to oxidize these compounds is responsible for several serious human diseases. Individuals with Zellweger syndrome are unable to make peroxisomes and therefore lack all the metabolism unique to that organelle. In X-linked adrenoleukodystrophy (XALD), peroxisomes fail to... 

Although it would seem reasonable to apply the electronic noses for measuring biological variables such as metabolic products and microbial activity, only a limited number of studies have been described. Of these, the following can be mentioned detection of infection bacteria activity in ulcers [10], microbial contamination in meat [11], classification of microbial strains [12,13], and monitoring of bioreactors [ 14]. 

Several mechanisms may contribute to the association of meat with colon cancer. The heterocyclic amines and polycyclic aromatic hydrocarbons present in cooked meat are metabolized, in the body, to mutagens that may condense with DNA to form adducts. If the adduct occurs at a vital base, and if the adduct is not promptly repaired, cancer may result. Another possible mechanism is related to the enhanced excretion of bile salts into the intestines that occurs with a high-fat diet. In brief, the increased amount of bile salts (with a high-fat diet) that reaches the large intestines is metabolized by the gut microflora to an increased amount of modified bile salts. Specifically, lithocholic acid and deoxycholic acid are formed. These modified bile salts are thought to contribute to the conversion of a normal gut cell to a cancer cell. Recent studies suggest that chronic exposure of gut cells to these modified bile salts may result in chronic activation of protein kinase C and chronic... 

Aromatic amines are released during biodegradation and metabolism of azo dyes. More recently, they have been detected as AIAs following the cooking of meat and fish. Bioactivation of heterocyclic amines leading to AIA-DNA adducts, involving activation through phase I and phase II, and mutations, is almost identical with the processes found with other aromatic amines. 

McLean, P., Reid, E., and Gurney, M. W., Effect of azo-dye carcinogenesis on enzymes concerned with urea synthesis in the rat. Biochem. J. 91, 464-473 (1964). McLean, P., and Rossi, F., Changes in the activities of urea-cycle enzymes after the administration of carbon tetrachloride. Biochem. J. 91, 261-270 (1964). McMurray, W. C., Mohyuddin, F., Bayer, S. M., and Rathbun, J. C., Citrul-linuria a disorder of amino acid metabolism associated with mental retardation. Int. Copenhagen Congr. Sci. Study Meat. Retard., Proc. 3rd 1, 117 (1964). McMurray, W. C., Rathbun, J. C., Mohyuddin, F., and Koegler, S. J., Citrul-linuria. Pediatrics 32, 347-357 (1963). 

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