Ontogenetic study of the effects of energetic nutrients on amino acid metabolism of rat cerebral cortex.
Karla Renata de OliveiraLiane Nanci RottaSandra Costa ValleDiogo André PilgerCristina W. NogueiraAna Maria Pandolfo FeóliElena Aida BernardDiogo O. SouzaMarcos Luiz Santos Perry
4
Citation
29
Reference
10
Related Paper
Citation Trend
Keywords:
Carbohydrate Metabolism
Abstract Transport and pathways of leucine and glutamine degradation were evaluated in resting human peripheral lymphocytes and compared with the changes induced by concanavalin A (ConA). Cells were incubated with [1‐ 14 C]leucine (0.15 mM), [U‐ 14 C]leucine (0.15 mM), or [U‐ 14 C]glutamine (0.4 mM) after culture with or without 2, 5, 7, or 10 μg/ml ConA for 2, 18, or 24 hours, respectively. Initial rates of transport of leucine and glutamine were augmented 2.7‐fold and threefold by the mitogen. Leucine transamination, irreversible oxidation, and catabolism beyond isovaleryl‐CoA were increased by 90%, 20%, and 60%, respectively. Glu‐tamine utilization increased threefold; accumulation of glutamate, aspartate, and ammonia increased by 700%, 50%, and 100%, respectively, and 14 CO 2 production by about 400% in response to ConA. The results indicate that ConA stimulates to about the same extent transport of leucine and glutamine into lymphocytes. Glutamine is mainly channeled into catabolic pathways, while leucine remains largely preserved. It is suggested that these metabolic changes provide more leucine for incorporation into protein and more N‐ and C‐atoms required for the synthesis of macromolecules and energy from glutamine.
Transamination
Catabolism
Cite
Citations (33)
Cite
Citations (5)
Abstract Butyrate, the four‐carbon fatty acid, is formed in the human colon by bacterial fermentation of carbohydrates (including dietary fiber), and putatively suppresses colorectal cancer (CRC). Butyrate has diverse and apparently paradoxical effects on cellular proliferation, apoptosis and differentiation that may be either pro‐neoplastic or anti‐neoplastic, depending upon factors such as the level of exposure, availability of other metabolic substrate and the intracellular milieu. In humans, the relationship between luminal butyrate exposure and CRC has been examined only indirectly in case–control studies, by measuring fecal butyrate concentrations, although this may not accurately reflect effective butyrate exposure during carcinogenesis. Perhaps not surprisingly, results of these investigations have been mutually contradictory. The direct effect of butyrate on tumorigenesis has been assessed in a number of in vivo animal models, which have also yielded conflicting results. In part, this may be explained by methodological differences in the amount and route of butyrate administration, which are likely to significantly influence delivery of butyrate to the distal colon. Nonetheless, there appears to be some evidence that delivery of an adequate amount of butyrate to the appropriate site protects against early tumorigenic events. Future study of the relationship between butyrate and CRC in humans needs to focus on risk stratification and the development of feasible strategies for butyrate delivery.
Cite
Citations (213)
Cite
Citations (49)
Essential amino acid
Cite
Citations (34)
Abstract A haemolytic method has been used for the determination of the isotonic concentrations of dextrose, fructose, galactose and mannose. Fructose, galactose and mannose produce haemolytic effects deviating from those of dextrose. The isotonic concentration in mM per cent of fructose was found to be 20.3; of galactose, 38.9; of mannose, 33.3; whereas that of dextrose is 26 mM per cent.
Cite
Citations (0)
The rate of leucine C-2 incorporation into glutamine was compared in control and septic rats. Female Sprague-Dawley rats (n = 46, 210-260 g) were fed parenterally for 3 days and then randomized into two groups (control and septic). Sepsis was induced by the injection of 10(10) live Escherichia coli/kg on day 4 into the septic group. Rats in each group were given a continuous (8 h) infusion of one of three different isotopes. The isotopes were given 24 h after inoculation. Leucine oxidation and incorporation into protein were determined with [1-13C]leucine; glutamine flux and oxidation were determined with [5-13C]glutamine, and the fraction of leucine C-2 incorporated into glutamine was determined by giving [1,2-13C]leucine. Results were as follows: sepsis caused a significant increase in the rate of leucine C-2 incorporation into glutamine (66.0 +/- 3.7 as against 29.6 +/- 3.7 mumol/h per kg, P less than 0.01). This increase was due to both an increase in glutamine production (2331 +/- 76 as against 1959 +/- 94 mumol/h per kg, P less than 0.01) and an increase in the proportion of glutamine derived from leucine (2.83 +/- 0.27% as against 1.51 +/- 0.31%, P less than 0.01). The ratio of leucine C-2 incorporated into glutamine to leucine oxidized increased from 7.16 +/- 0.91% to 11.49 +/- 1.12% with sepsis (P less than 0.05).
Cite
Citations (33)
Cite
Citations (19)
Distal colon
Short-chain fatty acid
Cite
Citations (4)
Metabolites produced by microbial fermentation in the human intestine, especially short-chain fatty acids (SCFAs), are known to play important roles in colonic and systemic health. Our aim here was to advance our understanding of how and why their concentrations and proportions vary between individuals. We have analysed faecal concentrations of microbial fermentation acids from 10 human volunteer studies, involving 163 subjects, conducted at the Rowett Institute, Aberdeen, UK over a 7-year period. In baseline samples, the % butyrate was significantly higher, whilst % iso-butyrate and % iso-valerate were significantly lower, with increasing total SCFA concentration. The decreasing proportions of iso-butyrate and iso-valerate, derived from amino acid fermentation, suggest that fibre intake was mainly responsible for increased SCFA concentrations. We propose that the increase in % butyrate among faecal SCFA is largely driven by a decrease in colonic pH resulting from higher SCFA concentrations. Consistent with this, both total SCFA and % butyrate increased significantly with decreasing pH across five studies for which faecal pH measurements were available. Colonic pH influences butyrate production through altering the stoichiometry of butyrate formation by butyrate-producing species, resulting in increased acetate uptake and butyrate formation, and facilitating increased relative abundance of butyrate-producing species (notably
Valerate
Short-chain fatty acid
Cite
Citations (20)