Metabolic association

Stable metabolic associations generally between pairs of anaerobic bacteria have been termed syntrophs, and these are effective in degrading a number of aliphatic carboxylic acids or benzoate under anaerobic conditions. These reactions have been discussed in reviews (Schink 1991, 1997 Lowe et al. 1993) that provide lucid accounts of the role of syntrophs in the degradation of complex organic matter. Two examples are given here to illustrate the experimental intricacy of the problems besetting the study of syntrophic metabolism under anaerobic conditions ... 

Muscle spasm. The pain induced by muscle spasm results partially from the direct effect of tissue distortion on mechanical nociceptors. Muscle spasm also causes tissue ischemia. The increased muscle tension compresses blood vessels and decreases blood flow. Furthermore, the increased rate of metabolism associated with the spasm exacerbates the ischemia. As discussed earlier, ischemia leads to stimulation of polymodal nociceptors. 

Proprioceptors originating in muscles and joints of the exercising limbs provide substantial input to the medullary respiratory center. In fact, even passive movement of the limbs causes an increase in ventilation. Therefore, the mechanical aspects of exercise also contribute to the ventilatory response. The increased metabolism associated with exercise increases body temperature, which further contributes to the increase in ventilation during exercise. (Not surprisingly, ventilation is also enhanced in response to a fever.) Exercise is associated with a mass sympathetic discharge. As a result, epinephrine release from the adrenal medulla is markedly increased. Epinephrine is believed to stimulate ventilation. 

The remarkable processes of life and decay are based on the ability of enzyme systems to function in a dual role in the dynamic metabolism associated with living systems. On the one hand, the enzymes present in organisms promote the synthesis of complex organic compounds from low molecular weight intermediates, and, on the other hand and simultaneously, other enzymes present therein facilitate the degradation of such compounds. Thus, in the study of the source and ultimate fate of a natural substance in living cells, the investigation of both the pathway of its synthesis and its breakdown are of equal importance. 

The oral form of idazoxan is readily absorbed and has a mean bioavailability of only 34% in humans, indicative of a high first-pass metabolism associated with a plasma half-life of only 5.6 hours. The drug lacks any affinity for muscarinic or histaminergic receptors and does not have any cholinergic or sedative side effects. Side effects that have been reported are consistent with idazoxan-enhancing sympathoneural activity, namely, exertional tachycardia. 

Table 6.2.2 Typical CSF profiles of HVA, 5HIAA and 3-methyldopa (3-MD) for the inborn errors of metabolism associated with a disruption of biogenic amine metabolism. A downward-pointing arrow indicates that a particular metabolite is below the established reference range. An upward pointing arrow is indicative that a metabolite is above the established reference range. WR indicates that the concentration of the metabolite is likely to be within the reference range. AADC Aromatic amino acid decarboxylase, PNPO pyridox(am)ine-5 -phosphate oxidase...

Meguro K, Hatazawa J, Yamaguchi T, Itoh M, Matsuzawa T, Ono S, Miyazawa H, Hishinuma T, Yanai K, Sekita Y et al (1990) Cerebral circulation and oxygen metabolism associated with subclinical periventricular hyperintensity as shown by magnetic resonance imaging. Ann Neurol 28 378-383... 

Understand the mechanisms for /V-acetylglucosamine biosynthesis and degradation of fructose and galactose, and inborn errors of metabolism associated with these pathways Appreciate the physiologic role of the glucuronate pathway and the inborn errors of metabolism associated with its malfunction ... 

Porrino, L., 6c Lucignani, G. (1987). Different patterns of local brain energy metabolism associated with high and low doses of methylphenidate Relevance to its action in hyperactive children. Biological Psychiatry, 22, 126-128. 

Amino Acid Metabolism Associated with Anaerobic Exercise... 

Einspahr, K.J., Peeler, T.C. and Thompson, G.A.Jr., 1988, Rapid changes in polyphosphoinositide metabolism associated with the response of Dunaliella salina to hypoosmotic shock. J. Biol. Chem. 263 5775-5779. 

Systematic large studies of the incidence of HEXA abnormalities among patients in common diagnostic categories such as schizophrenia are in short supply. What studies have been done encourage further work (Goodman, 1994). Studies of another inborn error of metabolism associated with schizophrenia syndromes, metachromatic leukodystrophy, have shown a high incidence of abnormalities in... 

Ethanol production is essentially redox neutral however metabolism associated with biomass production generates nett NADH, which is oxidised largely by glycerol production. Other important NADH oxidising reactions with flavour implications are the production of 2,3-butanediol, L-malic acid and succinic add. When glycerol production is stimulated by non-growth associated reactions (i.e. osmotic stress) NAD+ reduction occurs by other reactions including the oxidation of acetaldehyde to acetic acid... 

Lactic acidosis occurs in two clinical settings (1) type A (hypoxic), associated with decreased tissue oxygenation, such as shock, hypovolemia, and left ventricular failure and (2) type B (metabolic), associated with disease (e.g., diabetes melUtus, neoplasia, liver disease), drugs and/or toxins (e.g., ethanol, methanol, and salicylates), or inborn errors of metabolism (e.g., methylmalonic aciduria, propionic acidemia, and fatty acid oxidation defects). Lactic acidosis is not uncommon and occurs in approximately 1% of hospital admissions. It has a mortality rate greater than 60%, which approaches 100% if hypotension is also present. Type A is much more common. 

Renal osteodystrophy includes all of the disorders of bone and mineral metabolism associated with chronic renal failure. The renal bone diseases include both... 

B5a. Bickel, H., Feist, D., Muller, H., Quadbeck, G., and Kekomaki, M., Ornithi-naemla. Another disorder of aminoacid metabolism associated with brain damage. Ger. Med. Monthly 14, 101-105 (1969). 

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). 

H19. Hsia, D. Y.-Y., Detection and treatment of inborn errors of metabolism associated with mental deficiency. In Enz5rmes in Mental Health (G. J. Martin and B. Kisch, eds.), pp. 121-151. Lippincott, Philadelphia, Pennsylvania, 1966. 

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