Research Topics
Species | J T BrosnanSummaryAffiliation: Memorial University of Newfoundland Country: Canada Publications
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Publications
Methylation demand: a key determinant of homocysteine metabolismJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
Acta Biochim Pol 51:405-13. 2004..There are also important genetic influences on homocysteine metabolism...- Amino acids and the regulation of methyl balance in humansJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland, Canada
Curr Opin Clin Nutr Metab Care 10:52-7. 2007..Amino acids are intimately involved in these processes... - Interorgan amino acid transport and its regulationJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NF Canada A1B 3X9
J Nutr 133:2068S-2072S. 2003..There is no single means of regulating amino acid fluxes; rather, such varied mechanisms as substrate supply, enzyme activity, transporter activity and competitive inhibition of transport are all found... 
Creatine synthesis is a major metabolic process in neonatal piglets and has important implications for amino acid metabolism and methyl balanceJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada A1B 3X9
J Nutr 139:1292-7. 2009..Creatine synthesis is a quantitatively major metabolic process in piglets...- Creatine: endogenous metabolite, dietary, and therapeutic supplementJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland, Canada
Annu Rev Nutr 27:241-61. 2007..It is evident that creatine plays a critical, though underappreciated, role in brain function... - The sulfur-containing amino acids: an overviewJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada A1B 3X9
J Nutr 136:1636S-1640S. 2006..Cysteine may be converted to such important products as glutathione and taurine. Taurine is present in many tissues at higher concentrations than any of the other amino acids. It is an essential nutrient for cats... - Branched-chain amino acids: enzyme and substrate regulationJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada
J Nutr 136:207S-11S. 2006..Cytosolic and mitochondrial isoenzymes of BCAT have been identified. They are thought to play an important role in brain neurotransmitter metabolism... - Amino acids, then and now--a reflection on Sir Hans Krebs' contribution to nitrogen metabolismJ T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
IUBMB Life 52:265-70. 2001..This paper addresses three of Krebs' early contributions-urea synthesis, glutamine metabolism, and D-amino acid oxidase-and relates them to our modern understanding of amino acid metabolism... - Creatine metabolism and the urea cycleJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada
Mol Genet Metab 100:S49-52. 2010..It is clear that patients with urea cycle disorders also have altered creatine metabolism. Whether this contributes in a significant way to their neurological symptoms remains an open question... - The metabolic burden of creatine synthesisJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada
Amino Acids 40:1325-31. 2011..Creatine synthesis is, therefore, a quantitatively major pathway in amino acid metabolism and imposes an appreciable burden on the metabolism of methionine and of arginine... 
Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfurationSimon G Lamarre
Dept of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada
Am J Physiol Endocrinol Metab 302:E61-7. 2012....- Methylation demand and homocysteine metabolism: effects of dietary provision of creatine and guanidinoacetateL M Stead
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland, Canada A1B 3X9
Am J Physiol Endocrinol Metab 281:E1095-100. 2001..Creatine, however, was without effect. These results suggest that homocysteine metabolism is sensitive to methylation demand imposed by physiological substrates... - Hyperglucagonemia in rats results in decreased plasma homocysteine and increased flux through the transsulfuration pathway in liverR L Jacobs
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
J Biol Chem 276:43740-7. 2001..These results indicate that glucagon can regulate plasma homocysteine through its effects on the hepatic transsulfuration pathway... - Effects of streptozotocin-induced diabetes and of insulin treatment on homocysteine metabolism in the ratR L Jacobs
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
Diabetes 47:1967-70. 1998..These results suggest that insulin is involved in the regulation of plasma homocysteine concentrations by affecting the hepatic transsulfuration pathway, which is involved in the catabolism of homocysteine... - Threonine metabolism in isolated rat hepatocytesJ D House
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X9, Canada
Am J Physiol Endocrinol Metab 281:E1300-7. 2001..In summary, the majority of threonine oxidation occurs through the threonine dehydratase pathway in rat hepatocytes, and threonine oxidation is increased by glucagon, which also increases threonine's transport... - Creatine synthesis: production of guanidinoacetate by the rat and human kidney in vivoErica E Edison
Dept of Biochemistry, Memorial Univ of Newfoundland, St John s, NL, Canada, A1B 3X9
Am J Physiol Renal Physiol 293:F1799-804. 2007..9 microM. In humans, [GAA] was 2.4 microM in arterial plasma, with a renal A-V difference of -1.1 microM. These studies show, for the first time, that GAA is produced by both rat and human kidneys in vivo... - Hepatic glutaminase--a special role in urea synthesis?John T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland A1B 3X9, Canada
Nutrition 18:455-7. 2002..To investigate the relationship between hepatic glutaminase and the urea cycle with particular reference to the possibility of the existence of a metabolic channel between glutaminase and carbamylphosphate synthetase I (CPS-I)... - Is it time to reevaluate methyl balance in humans?Lori M Stead
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
Am J Clin Nutr 83:5-10. 2006.... - Systemic activation of glutamate dehydrogenase increases renal ammoniagenesis: implications for the hyperinsulinism/hyperammonemia syndromeJason R Treberg
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland, Canada
Am J Physiol Endocrinol Metab 298:E1219-25. 2010..These results are discussed in relation to the organ source of the ammonia in the HI/HA syndrome as well as the role of GDH in regulating renal ammoniagenesis... - Orotic acid excretion and arginine metabolismMargaret E Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada A1B 3X9
J Nutr 137:1656S-1661S. 2007.... - The Fourth Workshop on the Assessment of Adequate intake of Dietary Amino Acids: general discussion of sessions 1 and 2John T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, Canada
J Nutr 135:1576S-9S. 2005 - A window into cellular metabolism: hepatic metabolism of (15)N-labelled substratesJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NF, Canada A1B 3X9
Metab Eng 6:6-11. 2004..Our studies indicate that a metabolic channel does not exist between glutaminase and carbamoylphosphate synthetase 1... - Methylation demand and homocysteine metabolismLori M Stead
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, Canada A1B 3X9
Adv Enzyme Regul 44:321-33. 2004 - Renal arginine metabolismMargaret E Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada, A1B 3X9
J Nutr 134:2791S-2795S; discussion 2796S-2797S. 2004..Arginine is transported out of the proximal tubular cells at the basolateral membrane by another heteromeric transporter, which also transports lysine and ornithine. Defects in this transporter cause lysinuric protein intolerance... - The simultaneous determination of NAD(H) and NADP(H) utilization by glutamate dehydrogenaseJason R Treberg
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada
Mol Cell Biochem 344:253-9. 2010..These results illustrate that simple assumptions of cofactor preference by mammalian GDH are incomplete without an appreciation of allosteric effects when both cofactors are simultaneously present... - Homocysteine metabolism in diabetesE P Wijekoon
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, Canada A1B 3X9
Biochem Soc Trans 35:1175-9. 2007.... - Creatine synthesis: hepatic metabolism of guanidinoacetate and creatine in the rat in vitro and in vivoRobin P da Silva
Dept of Biochemistry, Memorial Univ of Newfoundland, St John s, NL, Canada A1B3X9
Am J Physiol Endocrinol Metab 296:E256-61. 2009..They also illustrate the interplay between the dietary provision of creatine and its de novo synthesis and point to the crucial role of renal AGAT expression in regulating creatine synthesis in the rat... - Amino acid metabolism in the Zucker diabetic fatty rat: effects of insulin resistance and of type 2 diabetesEnoka P Wijekoon
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada
Can J Physiol Pharmacol 82:506-14. 2004..These changes in amino acid concentrations are similar to changes seen in type 1 diabetes. It is evident that insulin resistance alone is capable of bringing about many of the changes in amino acid metabolism observed in type 2 diabetes... - Homocysteine metabolism in ZDF (type 2) diabetic ratsEnoka P Wijekoon
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland, Canada
Diabetes 54:3245-51. 2005..These results emphasize the importance of betaine metabolism in determining plasma Hcy levels in type 2 diabetes... - Alanine metabolism in the perfused rat liver. Studies with (15)NJ T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
J Biol Chem 276:31876-82. 2001..Under these circumstances, the liver must summon internal pools of protein in order to accommodate the ammonia burden... - Application of 15N to the study of hepatic nitrogen metabolismJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NF A1B 3X9, Canada
Adv Enzyme Regul 42:305-15. 2002 - Lack of phosphatidylethanolamine N-methyltransferase alters plasma VLDL phospholipids and attenuates atherosclerosis in miceYang Zhao
Department of Biochemistry, University of Alberta, Edmonton, Canada
Arterioscler Thromb Vasc Biol 29:1349-55. 2009..We, therefore, tested the hypothesis that lack of phosphatidylethanolamine N-methyltransferase (PEMT), a hepatic enzyme catalyzing PC biosynthesis, attenuates the development of atherosclerosis... - Characterization of homocysteine metabolism in the rat kidneyJ D House
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
Biochem J 328:287-92. 1997..These studies indicate that factors that influence the transulphuration of homocysteine may influence the renal clearance of this amino acid... - Suckling rat pups accumulate creatine primarily via de novo synthesis rather than from dam milkSimon G Lamarre
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
J Nutr 140:1570-3. 2010..The great bulk of creatine accretion was via de novo synthesis by the pups, which imposed a substantial metabolic burden on them... - Hormonal regulation of cystathionine beta-synthase expression in liverShobhitha Ratnam
Department of Biochemistry, Memorial University of Newfoundland, St John s, Newfoundland A1B 3X9, Canada
J Biol Chem 277:42912-8. 2002..These results show that insulin has a direct role in regulating homocysteine metabolism. Altered insulin levels in diseases such as diabetes may influence homocysteine metabolism by regulating the hepatic transsulfuration pathway... - Hepatic glutamate metabolism: a tale of 2 hepatocytesMargaret E Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St John s, Canada
Am J Clin Nutr 90:857S-861S. 2009..Knowledge of the acinar localization of metabolic processes is essential for an appreciation of their relation to other hepatic functions and their regulation... - Effects of diabetes and insulin on betaine-homocysteine S-methyltransferase expression in rat liverShobhitha Ratnam
Dept. of Biochemistry, Memorial University of Newfoundland, St. John's, NF, Canada, A1B 3X9
Am J Physiol Endocrinol Metab 290:E933-9. 2006.... - New insights into creatine function and synthesisMargaret E Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, Canada A1B 3X9
Adv Enzyme Regul 47:252-60. 2007 - Elevated tissue betaine contents in developing rats are due to dietary betaine, not to synthesisKathy A Clow
Department of Biochemistry, Memorial University of Newfoundland, St John s, NL, A1B 3X9, Canada
J Nutr 138:1641-6. 2008..We conclude that the transient increase in betaine reflects high dietary betaine and not a change in endogenous betaine synthesis... - Metabolic design principles: chemical and physical determinants of cell chemistryJohn T Brosnan
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada A1B 3X9
Adv Enzyme Regul 45:27-36. 2005 - Plasma homocysteine is regulated by phospholipid methylationAnna A Noga
Department of Biochemistry and Canadian Institutes for Health Research Group on the Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
J Biol Chem 278:5952-5. 2003..Thus, phosphatidylethanolamine N-methyltransferase is an important source of plasma homocysteine and a potential therapeutic target for hyperhomocysteinemia... - Homocysteine and cardiovascular disease: interactions between nutrition, genetics and lifestyleJohn T Brosnan
Biochemistry Department, Memorial University of Newfoundland, St Johns, Newfouondland
Can J Appl Physiol 29:773-80. 2004..This is due to an impairment in homocysteine removal in renal disease. The role of these factors, and of modifiable lifestyle factors, in affecting methionone metabolism and in determining plasma homocysteine levels is discussed... - Physiological regulation of phospholipid methylation alters plasma homocysteine in miceRene L Jacobs
Canadian Institutes of Health Research Group on the Molecular and Cell Biology of Lipids and Department of Biochemistry, University of Alberta, Edmonton, Canada
J Biol Chem 280:28299-305. 2005..These data suggest that phospholipid methylation in the liver is a major consumer of AdoMet and a significant source of plasma Hcy... - Hyperglycinemia due to folate deficiency in rats: evidence for the lack of involvement of the hepatic glycine cleavage systemTyra M Dickson
Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2
J Nutr Biochem 16:736-42. 2005.... - Methyl balance and transmethylation fluxes in humansS Harvey Mudd
Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, MD 20892, USA
Am J Clin Nutr 85:19-25. 2007.... - Localization-independent regulation of homocysteine secretion by phosphatidylethanolamine N-methyltransferaseDavid J Shields
Department of Biochemistry and Canadian Institutes of Health Research Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
J Biol Chem 280:27339-44. 2005..Thus, our data suggest that Hcy homeostasis is regulated concomitantly with PEMT activity but independently of PEMT localization...