PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “VALERIC ACID”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed1976

The effect of selenium or vitamin E supplementation on volatile fatty acid content of rumen liquor in sheep fed a purified diet.

Twelve crossbred wethers, four per diet, were allotted at random as follows: (1) purified control diet; (2) purified diet plus a weekly oral dose of 1 mg sodium selenite per sheep; (3) purified diet plus a weekly oral dose of 1000 l.U. vitamin E. The wethers were maintained on the diets for six months. Weight gains during the initial 140 days of the experiment were significantly greater in selenium (Se)-supplemental sheep than in the others. The rumem liquor from the untreated sheep contained lower proportions (molar %) of acetic acid than from the Se or vitamin E-supplemented sheep and had higher butyric acid concentration than the Se-supplemented sheep. Concentrations of acetate, butyrate and valerate were higher in vitamin E than in Se-supplemented sheep. In addition, the concentration and molar percent of isovaleric acid was significantly higher in Se-supplemented sheep than in the other sheep.

Acetates↗
PubMed1992

Hindgut fermentation in the wombats: two marsupial grazers.

The wombats Vombatus ursinus and Lasiorhinus latifrons have a capacious proximal colon with only a vestigial caecum. The pattern of microbial fermentation in the hindgut of both species was studied in captive animals fed a pelleted straw diet and in wild wombats feeding on their natural winter diets. Digesta pH was low in the stomach but near neutrality along the hindgut, indicating effective absorption and/or buffering of the colonic contents. Initial proportions and production rates of short chain fatty acids in vitro reflected the fermentation of plant cell walls. Proportions of isobutyrate, isovalerate and n-valerate increased towards the distal colon indicating proteolysis and subsequent fermentation of amino acids. The low ammonia content of digesta fluid suggested that ammonia released from these amino acids was absorbed and utilized by the wombats and their gut microbes. Wild wombats had higher concentrations and production rates of short chain fatty acids than captive animals, which was consistent with the higher apparent digestibility of their natural diet. The energy from short chain fatty acids in captive animals was 30-33% of digestible intake. Energy intakes were low and similar to resting metabolic rates estimated for marsupials. Actual resting metabolic rates of the wombats are probably lower than these estimates, and the proportion of energy derived from fermentation substantially higher than the 53-61% estimated in wild wombats. The energy from fermentation clearly enables wombats to utilize diets high in fibre.

Animals↗
PubMed2003

Kinetics of thermophilic, anaerobic oxidation of straight and branched chain butyrate and valerate.

The degradation kinetics of normal and branched chain butyrate and valerate are important in protein-fed anaerobic systems, as a number of amino acids degrade to these organic acids. Including activated and primary wastewater sludge digesters, the majority of full-scale systems digest feeds with a significant or major fraction of COD as protein. This study assesses the validity of using a common kinetic parameter set and biological catalyst to represent butyrate, n-valerate, and i-valerate degradation in dynamic models. The i-valerate degradation stoichiometry in a continuous, mixed population system is also addressed, extending previous pure-culture and batch studies. A previously published mathematical model was modified to allow competitive uptake of i-valerate, and used to model a thermophilic manure digester operated over 180 days. The digester was periodically pulsed with straight and branched chain butyrate and valerate. Parameters were separately optimized to describe butyrate, i-valerate, and n-valerate degradation, as well as a lumped set optimized for all three substrates, and nonlinear, correlated parameter spaces estimated using an F distribution in the objective function (J). Each parameter set occupied mutually exclusive parameter spaces, indicating that all were statistically different from each other. However, qualitatively, the influence on model outputs was similar, and the lumped set would be reasonable for mixed acid digestion. The main characteristic not represented by Monod kinetics was a delay in i-valerate uptake, and was compensated for by a decreased maximum uptake rate (k(m)). Therefore, the kinetics need modification if fed predominantly i-valerate. Butyrate (i- and n-) and n-valerate could be modeled using stoichiometry consistent with beta-oxidation degradation pathways. However, i-valerate produced acetate only, supporting the stoichiometry of a reaction determined by other researchers in pure culture. Therefore, lumping i-valerate stoichiometry with that of n-valerate will not allow good system representation, especially when the feed consists of proteins high in leucine (which produces i-valerate), and the modified model structure and stoichiometry as proposed here should be used. This requires no additional kinetic parameters and one additional dynamic concentration state variable (i-valerate) in addition to the variables in the base model.

Acetates↗
PubMed1984

Effect of carbon-4 and carbon-5 volatile fatty acids on growth of mixed rumen bacteria in vitro.

Mixed ruminal bacteria (400 mg cells/liter) were incubated in artificial media containing ammonia, sodium carbonate, macrominerals, vitamins, sulfide, microminerals, acetate, propionate, and butyrate. When mixed carbohydrates (equal parts glucose, maltose, sucrose, cellobiose, and soluble starch) were added at 155 mg/liter per h for 10 h, average bacterial growth rate was slow, and dry weight yield was greater than 23%. Additions of isobutyrate, valerate, isovalerate, and 2 methylbutyrate had little influence on synthesis of bacterial dry weight, deoxyribonucleic acid, ribonucleic acid, or carbohydrate. When a timothy hay inoculum was used, isovalerate and 2 methyl-butyrate increased protein synthesis by 11.2 and 16.4%, but isobutyrate and valerate alone were without effect. All four acids combined increased bacterial protein by 18.7%. Responses with an inoculum of 60% concentrate and mixed hay were smaller and not statistically different from control incubations. Low concentrations of Trypticase (less than 250 mg/liter) improved efficiency of microbial protein synthesis from organic matter, but more was associated with decreased efficiency and utilization of extracellular ammonia.

Ammonia↗
PubMed2005

Effects of adding valerate, caproate, and heptanoate to ruminal buffers on splanchnic metabolism in steers under washed-rumen conditions.

Four steers fitted with a ruminal cannula and chronic indwelling catheters in the mesenteric artery, mesenteric vein, hepatic portal vein, hepatic vein, and the right ruminal vein were used to study VFA absorption from bicarbonate buffers incubated in the washed reticulorumen, and metabolism by splanchnic tissues. Portal and hepatic vein blood flows were determined by infusion of p-aminohippurate into the mesenteric vein. The steers were subjected to four experimental treatments in a Latin square design. The treatments were Control (ruminal bicarbonate buffer with [mmol/kg]: acetate = 72; propionate = 30; isobutyrate = 2.1; butyrate = 12; valerate = 1.2; caproate = 0; and heptanoate = 0); Val (same as control except for valerate = 8 mmol/kg); Cap (same as control except for caproate = 3.5 mmol/kg); and Hep (same as control except for heptanoate = 3 mmol/kg). All buffers were incubated for 90 min in the rumen, and ruminal VFA absorption rates were maintained by continuous intraruminal infusion of VFA. The arterial concentrations of valerate and heptanoate showed a small increase (< or = 1 micromol/L; P < 0.05) with inclusion of the respective acid in the ruminal buffer, but no change (P = 0.57) in arterial concentration of caproate was detected. Valerate increased (P < 0.05) the net portal flux of butyrate and valerate, as well as the net splanchnic flux of propionate, butyrate, and valerate. With Cap and Hep, the net portal flux of caproate and heptanoate accounted for 54 and 45% of ruminal disappearance rates, respectively, indicating that these acids were extensively metabolized by the ruminal epithelium. Caproate was ketogenic both in the ruminal epithelium and in the liver, and Cap increased (P < 0.05) the arterial concentration, ruminal vein minus arterial concentration difference, net hepatic flux, and net splanchnic flux of 3-hydroxybutyrate. The net hepatic flux of glucose decreased (P = 0.02) with Cap and Hep compared with Control and Val; however, no effect (P = 0.14) on the net splanchnic flux of glucose could be detected. We conclude that the strong biological activity of valerate, caproate, and heptanoate warrant increased emphasis on monitoring their ruminal presence and their potential systemic effects on ruminant metabolism.

Absorption↗
PubMed1977

Essential fatty acid deficient hairless mouse: the effects of topical agents on the epidermis.

Essential fatty acid deficient (EFA deficient) hairless mice were used to test the ability of topical agents to reduce the high epidermal DNA synthesis and acanthosis present in EFA deficiency. An established therapeutic agent known to be effective in psoriasis (betamethasone 17-valerate) significantly reduced the epidermal DNA synthesis, mitotic count and epidermal cell thickness. Linoleic acid reduced DNA synthesis and returned epidermal histology towards that of normal skin. Prostaglandin E2 analogue (15 (S)-15-methyl PGE2 methyl ester) reduced epidermal DNA synthesis both in treated and distant skin sites. Prostaglandin E2 was less effective than the analogue but slightly reduced epidermal DNA synthesis and thickness. Prostaglandin F2alpha had no obvious effect on the epidermis. Chlorambucil reduced epidermal DNA synthesis and thickness. Vitamin A acid increased DNA synthesis and epidermal cell thickness but reduced the hyperkeratosis of EFA deficiency. A rapid epidermal cell transit was found in EFA deficient mice, approximately three times faster than in normal mouse epidermis.

Administration, Topical↗
PubMed1982

Properties of acetate kinase isozymes and a branched-chain fatty acid kinase from a spirochete.

Spirochete MA-2, which is anaerobic, ferments glucose, forming acetate as a major product. The spirochete also ferments (but does not utilize as growth substrates) small amounts of l-leucine, l-isoleucine, and l-valine, forming the branched-chain fatty acids isovalerate, 2-methylbutyrate, and isobutyrate, respectively, as end products. Energy generated through the fermentation of these amino acids is utilized to prolong cell survival under conditions of growth substrate starvation. A branched-chain fatty acid kinase and two acetate kinase isozymes were resolved from spirochete MA-2 cell extracts. Kinase activity was followed by measuring the formation of acyl phosphate from fatty acid and ATP. The branched-chain fatty acid kinase was active with isobutyrate, 2-methylbutyrate, isovalerate, butyrate, valerate, or propionate as a substrate but not with acetate as a substrate. The acetate kinase isozymes were active with acetate and propionate as substrates but not with longer-chain fatty acids as substrates. The acetate kinase isozymes and the branched-chain fatty acid kinase differed in nucleoside triphosphate and cation specificities. Each acetate kinase isozyme had an apparent molecular weight of approximately 125,000, whereas the branched-chain fatty acid kinase had a molecular weight of approximately 76,000. These results show that spirochete MA-2 synthesizes a branched-chain fatty acid kinase specific for leucine, isoleucine, and valine fermentation. It is likely that a phosphate branched-chain amino acids is also synthesized by spirochete MA-2. Thus, in spirochete MA-2, physiological mechanisms have evolved which serve specifically to generate maintenance energy from branched-chain amino acids.

Acetate Kinase↗
PubMed1987

Delta-guanidinovaleric acid as an endogenous and specific GABA-receptor antagonist: electroencephalographic study.

Sporadic spike discharges recorded on EEGs from epidural electrodes appeared 5-10 min after topical application of 0.3 nmol delta-guanidinovaleric acid (DGVA) on the pia mater of the sensorimotor cortex, on the same side as the application. Spike discharges induced by DGVA were completely suppressed within 10 min of supplementary application of GABA (50 nmol), (3R)-(-)-4-amino-3-hydroxybutanoic acid (L-GABOB) (5 nmols) or muscimol (5 nmols) on the pia mater, but the discharges were not affected by supplementing with 500 nmol of alpha-amino-DGVA, i.e., arginine (Arg). Whereas spike discharges were not induced by DGVA together with L-GABOB or muscimol, DGVA applied together with Arg induced spike discharges. Neither phenobarbital (PB) (20 mg/kg, i.m.), diazepam (DZ) (10 mg/kg, i.p.), sodium valproate (200 mg/kg, i.p.) nor diphenylhydantoin (20 mg/kg, i.p.) showed any suppressive effects on spike discharges induced by DGVA. DGVA induced spike discharges 20 min after pre-injection of PB or DZ. These electroencephalographic findings suggest that DGVA, which has one more carbon in its chain than N-amidino-GABA, might act directly on the GABA-receptor to induce spike discharges and might be a specific GABA-receptor antagonist.

Animals↗
PubMed1988

Luminal propionate-induced secretory response in the rat distal colon in vitro.

1. The stimulatory action of propionate on colonic electrolyte transport and involvement of the enteric reflex in this was studied in vitro using an Ussing chamber in the rat. The short-circuit current (Isc) and bidirectional fluxes of Na+ and Cl- were measured. Mucosa-submucosa preparations, containing the submucosal nerve, from the distal colon were used in most cases. 2. Mucosal application of propionate caused transient increases in the transmural potential difference, with the mucosal side negative, Isc and conductance. Serosal application of the acid had no effect. 3. Adaptation of the Isc response occurred when the acid was applied to the bathing solution cumulatively without washing out the first dose. If tissues were washed and held more than 20 min before the next application, the response was almost completely restored. 4. The increase in Isc in response to propionate was concentration dependent, with a 50% effective concentration of approximately 7 x 10(-5) M. 5. Two other short-chain fatty acids (SCFAs), n-butyrate and n-valerate, but not acetate, increased Isc when added to the mucosal bathing solution. 6. Bumetanide (3 x 10(-5) M) and the serosal chloride-free condition, but not amiloride (10(-4) M), inhibited the responses of Isc to propionate. Propionate-stimulated Cl- secretion resulted mainly from an increase in unidirectional serosal-to-mucosal Cl- movement. Propionate did not affect the Na+ flux. 7. Tetrodotoxin (10(-7) M), somatostatin (10(-7) M) and hexamethonium (10(-4) M) inhibited the propionate-evoked increase in Isc by 40, 70 and 30%, respectively. 8. Atropine (10(-5) M) also inhibited the Isc-increase response to propionate more than 90%. 9. Pre-treatment (2 min) of the mucosal surface with procaine (5 x 10(-4) M) inhibited the propionate-evoked increase in Isc by 90%. 10. The results suggest that luminal propionate transiently stimulated the colonic chloride secretory response that is not due to direct action on colonocytes, but due in large part to release of acetylcholine at neuro-colonocyte junctions, probably via an enteric reflex involving a mucosal sensory mechanism, cholinergic motor nerves and submucosal ganglia.

Action Potentials↗
PubMed1988

Delta-aminovaleric acid antagonizes the pharmacological actions of baclofen in the central nervous system.

The action of delta-aminovaleric acid (AVA) on the muscle relaxant properties of baclofen, a GABAB receptor agonist, was investigated in two experimental models: (1) the pathologically increased muscle tone of the gastrocnemius muscle in spastic mutant Han-Wistar rats and (2) the Hoffmann (H)-reflex recorded from plantar foot muscles after electrical stimulation of the tibial nerve in barbiturate (60 mg/kg) anaesthetized rats. In both paradigms coadministration of AVA (500 nmol/5 microliter) antagonized the muscle relaxant action of intrathecally applied baclofen (0.2-2 nmol), but failed to affect the muscle relaxant effects of intrathecally injected muscimol (2-20 nmol). In contrast, coadministration of bicuculline (1 nmol) did block the muscle relaxant action of muscimol, but failed to alter the effects of baclofen. When administered alone, bicuculline (1 nmol), or AVA (500 nmol-2 mumol) were without intrinsic action in both paradigms. In an additional series of experiments we investigated the action of AVA on a supraspinal effect of baclofen. Coadministration of AVA (12.5 nmol/0.5 microliter) in the ventromedial thalamic nucleus antagonized the catalepsy induced by baclofen (ED50 10 pmol/0.5 microliter), as indicated by an increase in ED50 of baclofen by a factor of 4.835 and a parallel shift of the probit-log dosage regression line to the right. The parallel shift seems to be consistent with a competitive mechanism of action of AVA. This study presents evidence that AVA antagonizes central pharmacological actions of baclofen at both spinal and supraspinal sites without affecting the actions of a GABAA agonist, muscimol.

Animals↗
PubMed1991

Determination of short-chain fatty acids in equine caecal liquor by ion exchange high performance liquid chromatography after solid phase extraction.

A high performance liquid chromatography (HPLC) method was developed for the determination of seven short-chain fatty acids in equine caecal liquor. Samples were cleaned up on a Sep-pak (C18) cartridge, and the analyte was eluted from the extraction cartridge and filtered through a 0.45 micron cellulose nitrate filter. The analyte was chromatographed by ion exchange HPLC. Detection was by UV at 210 nm. Recovery from phosphate buffer (0.05 M, pH 7.0) and equine caecal liquor was 76.95% (lactic), 76.76% (valeric). The limit of (propionic), 89.35% (isobutyric), 88.73% (butyric), 80.33% (isovaleric) and 72.61% (valeric). The limit of detection of the short-chain fatty acids in phosphate buffer was 0.00006 M (lactic), 0.0001 M (acetic), 0.0002 M (propionic), 0.0001 M (isobutyric), 0.0002 M (butyric), 0.0002 M (isovaleric) and 0.0003 M (valeric). The specificity and sensitivity of this method was sufficiently high to allow the characterization of the pattern of these short-chain fatty acids in equine caecal liquor following intravenous administration of oxytetracycline at the recommended dose rate in a pony.

Animals↗
PubMed1990

The contribution of protein catabolism to metabolic decompensation in 3-hydroxy-3-methylglutaric aciduria.

Leucine and protein metabolism were studied using stable isotope techniques in 6-year-old twins with 3-hydroxy-3-methylglutaric aciduria during acute metabolic decompensation. The decompensation was preceded by prolonged fasting in twin 1 and by an upper respiratory infection in twin 2. Twin 2 was also studied when well (control study). During infection, leucine oxidation (36 mumol/kg per hour), protein catabolism (6.0 g/kg per day) and urinary excretion of major leucine metabolites (104 mumol/kg per hour) were all increased compared with the control study (16 mumol/kg per hour, 4.7 g/kg per day and 28 mumol/kg per hour respectively). During fasting, leucine oxidation (18 mumol/kg per hour) was unchanged and protein catabolism (4.1 g/kg per day) was decreased despite substantially increased urinary metabolite excretion (87 mumol/kg per hour) compared with the control study. These results indicate that protein mobilisation and leucine oxidation played important roles in metabolic decompensation during infection but not during fasting. It is likely that the increased metabolite excretion during fasting arose primarily from fatty acid catabolism, indicating the importance of this substrate in metabolic decompensation in 3-hydroxy-3-methylglutaric aciduria.

Amino Acid Metabolism, Inborn Errors↗
PubMedDate not supplied

Anaplerotic molecules: current and future.

This review presents the concepts of anaplerosis and cataplerosis in relation to the regulation of citric acid cycle operation. Anaplerosis is the re-filling of the catalytic intermediates of the cycle that carry acetyl-CoA as it is oxidized. The main anaplerotic substrates are pyruvate, glutamine/glutamate and precursors of propionyl-CoA (odd-chain fatty acids, specific amino acids, C(5)-ketone bodies). Cataplerosis balances anaplerosis by removing excess intermediates from the citric acid cycle. The properties of the main anaplerotic substrates are reviewed from the point of view of potential clinical applications to the treatment of some inherited and acquired conditions.

Acyl Coenzyme A↗
PubMed1986

A comparison of different formulations and dosage administrations of gemfibrozil.

To assess the lipid-regulating effects of 2 new gemfibrozil formulations, a nonblind parallel group comparison was performed using Finnish industrial workers with types IIA and IIB primary hyperlipoproteinemia. In all, 670 subjects were evaluated; 416 had total low density lipoprotein (LDL) cholesterol (serum total cholesterol--high density lipoprotein [HDL] cholesterol) levels greater than or equal to 200 mg/dl and thus qualified for the screening period of the trial. During this 2-month period, the subjects were placed on an optimal diet according to their Fredrickson phenotype. Those whose total LDL levels remained greater than or equal to 200 mg/dl until the end of the 2-month period (n = 321) were admitted to the active drug phase of the trial and randomized to 1 of 3 treatment groups. Group 1 received the standard gemfibrozil dosage of two 300-mg capsules 2 times a day, for a total daily dosage equal to 1,200 mg. Group 2 also received a 1,200-mg daily dose, given as a 600-mg tablet of gemfibrozil 2 times a day. Group 3 received a once-a-day dose of two 450-mg tablets in the evening. Preliminary results show that the alternate gemfibrozil formulations are thus far equal to the standard gemfibrozil dosage in their effects on blood lipids. Substantial decreases have been noted in serum cholesterol, serum triglycerides, LDL cholesterol and serum apolipoprotein B. The 3 formulations also produced similar increases in HDL cholesterol and its subfractions HDL2 and HDL3, as well as in serum apolipoproteins AI and AII.

Administration, Oral↗
PubMed1983

Analysis of porphyrin precursors, 5-aminolevulinic acid derivatives by isotachophoresis.

Porphyrin precursors, 5-aminolevulinic acid (ALA), 4,5-dioxovaleric acid (DOVA), and porphobilinogen (PBG) can be simultaneously and conveniently analyzed by isotachophoresis. The quantitative analysis requires a minimum of 12 nmol for ALA, 4 nmol for DOVA, and 35 nmol for PBG. The reproducibility determined as coefficient of variation for qualitative and quantitative determination is within 4 and 5%, respectively. Isotachophoresis permits simple, efficient and quantitative detection, and identification of ALA derivatives in a mixture.

Aminolevulinic Acid↗