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Results for “NICOTINIC ACID”

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At least 757 records · Page 42Linked to original sources
PubMed1988

Utilization of tryptophan, nicotinamide and nicotinic acid as precursors for nicotinamide nucleotide synthesis in isolated rat liver cells.

1. Incubation of isolated rat hepatocytes with nicotinamide or nicotinic acid showed that while both vitamers were taken up from the incubation medium, neither was utilized to any significant extent as a precursor of the nicotinamide nucleotide coenzymes, NAD and NADP, and neither was capable of preventing the loss of nucleotides that occurs on incubating the cells. 2. Incubation of hepatocytes with tryptophan showed that de novo synthesis from tryptophan permitted replacement of the nucleotides lost during incubation; at high concentrations of tryptophan there was an increase above the initial intracellular concentration of NAD(P). Incubation of hepatocytes with tryptophan also resulted in the formation and release from the cells of a considerable amount of niacin, as well as the two principal metabolities of NAD(P), N1-methyl nicotinamide and methyl pyridone carboxamide. 3. It is suggested that, in the liver, performed niacin is not utilized for nucleotide synthesis, and indeed the function of the liver appears to be synthesis of niacin from tryptophan, and its release for use by extrahepatic tissues that lack the pathway for de novo synthesis of nicotinamide nucleotides from tryptophan.

Animals↗
PubMed1984

Plasma clearance of nicotinic acid and rifamycin-SV, and their interaction in Gilbert's syndrome: application of a compartmental model.

The bicompartmental kinetics of nicotinic acid (NA) and rifamycin-SV (R-SV)--2 organic anions that probably share a common hepatic uptake mechanism--were studied in 7 cases of Gilbert's syndrome (GS) and in 7 healthy controls matched for sex and age. In GS the NA and R-SV uptake constants (K21) were significantly decreased. In GS patients, simultaneous loads of NA and R-SV, the latter at increasing doses, produced: 1) a progressive lowering only of R-SV K21; and 2) an increase in R-SV hepatic plasma reflux (K12). Changes in biliary excretion ( Kee ) and hepatocellular pool (Ke) of both NA and R-SV probably depend on the rates of uptake and reflux constants of the two anions. The study of the parameters of compartmental kinetics of NA and R-SV confirms that the two organic anions, which have different metabolic routes and/or a different affinity for intracellular carriers, share common uptake mechanisms.

Adolescent↗
PubMed2005

[Screening and identification of a strain for hydroxylation of nicotinic acid].

Strain screening was conducted on a large scale in order to develop a biotransforming process for 6-hydroxynicotinic acid production. A strain named as NA-1 was isolated from soil which could transform nicotinic acid into a new product showed by HPLC. The new product was identified as 6-hydroxynicotinic acid by MS and 1H-NMR. The morphology, physiological and biochemical characteristics of strain NA-1 were studied and showed that characteristics of strain NA-1 were essentially consistent with Pseudomonas putida. The analysis of 16S rDNA sequence from strain NA-1 suggested that strain NA-1 was clustered together with P. putida in phylogenetic tree and the sequence identity between stain NA-1 and Pseudomonas putida was 99%. So strain NA-1 was identified to P. putida.

Chromatography, High Pressure Liquid↗