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PubMed1993

[Physiology and clinical aspects of the extracellular bicarbonate pool: plea for cognizant use of HCO3-].

OBJECTIVE: Derived from literature data the function of bicarbonate (HCO3-) is described together with its extracellular pool, the regulating organs, and the clinical variations. DATA SOURCES AND SELECTION CRITERIA: The medical German and English literature was reviewed. No special literature retrieval was performed. Results from measurements at the author's laboratory were used. RESULTS: HCO3- may be described as the most potential nonrespiratory buffer base. For a 65 kg patient, the extracellular HCO3- pool amounts to approximately 350 mmol with a maximum tolerance limit of +/- 200 mmol. An influx of H+ ions (acidosis) and/or a reduction in the pCO2 (hyperventilation) will reduce this pool, whereas alkalosis and hypoventilation will enlarge it. The lungs (in close cooperation with the erythrocytes), liver and kidneys all contribute to the regulation of this HCO3- pool. The paramount organ for this regulation seems to be the liver, since it is able, even within a period of only a few hours, to eliminate much larger amounts of H+ ions (and correspondingly release HCO3-) than the kidneys are able to eliminate even under extreme conditions. It is primarily the liver which regulates the size of the HCO3- pool through the metabolism of the so-called metabolizable anions (bases) such as acetate, lactate, malate and citrate. The metabolism of these anions in the form of acetic, lactic, malic or citric acid requires (per mol) 1 mol H+ (acetate, lactate), 2 mol H+ (malate) or even 3 mol H+ (citrate), with the corresponding release of HCO3-. Iatrogenic alterations in the HCO3- pool occur more frequently than previously assumed. Infusion solutions may lead to a dilution acidosis (dilution of HCO3-), an infusion acidosis (addition of H+) or an infusion alkalosis (administration of metabolizable anions). CONCLUSION: An improvement in the declaration accompanying infusion solutions is recommended according to their actual pH-dependent composition. In particular, the concepts of base excess (BE, mmol/l) and BE pot. (mmol/l) should be introduced, in order to give an indication of potential alterations in the HCO3- pool after infusion and metabolism. This also applies to blood derivatives, where transfusion acidosis as well as alkalosis may occur, and in hemodialysis and peritoneal dialysis where the occurrence of acidosis and alkalosis during therapy need to be reckoned with.

Acid-Base Imbalance↗
PubMed1997

Effect of calcium addition and acidification on the quality characteristics of canned okra (Hibiscus esculentus L).

A study was conducted on calcium chloride treatments of canned okra acidified by adding either acetic, citric, lactic, malic or tartaric acids or by lactic fermentation. The quality of the processed okra was determined by physical, chemical, microbiological and sensory analyses after a two month storage period at room temperature. The results indicated the possibility of processing high quality canned okra by small canneries, with low cost equipment and low energy requirements. The acidification procedures ensure minimal risk of botulism.

Acetic Acid↗
PubMed2006

Assessment of urea degradation rate in model wine solutions by acid urease from Lactobacillus fermentum.

The specific activity (piA) of a whole cell acid urease preparation was assessed in model wine solutions at different levels of malic (M) and lactic acids, metabisulfite, ethanol, and pH by performing a central composite design. M and then pH were found to be the most controlling variables, their effects being practically coincident but of opposite sign. For urea concentrations up to approximately 1 mol m(-3) the ammonium formation rate was assumed of the pseudo-first-order with respect to urea, this being confirmed by two independent validation tests performed at 20 degrees C for as long as 24 h. In the case of real wines the effective pseudo-first-order kinetic rate constants were found to be smaller than those pertaining to the model solutions having the same wine composition and pH by a factor varying from 10 to 1000, this affecting significantly the specific urease treatment costs per liter of wine treated.

Ethanol↗
PubMed2006

The effects of weight cycling on serum leptin levels and lipogenic enzyme activities in adipose tissue.

Weight cycling is one of the widely used weight reduction strategies; however, the adverse effects of this method include regaining significant amounts of weight. The molecular mechanisms underlying weight gain following cycles of dietary deprivation and refeeding are still poorly understood. One of the possibilities is that repeated loss and gain of weight may promote fat deposition in adipose tissue. To test this hypothesis we investigated serum leptin levels and lipogenic enzyme activities in white adipose tissue (WAT) of male Wistar rats during 12 days of ad libitum feeding following multiple cycles of alternating food deprivation and refeeding. Rats subjected to eight cycles of food deprivation and refeeding (MFR group) showed significantly decreased circulating leptin levels when compared with control rats (nearly 50% decrease in leptin levels, P < 0.01). Throughout 12 days of ad libitum feeding, serum leptin levels increased modestly but remained significantly (24%, P < 0.05) lower than control levels. Fatty acid synthase (FAS) and malic enzyme (ME) activities (chosen as representatives of enzymes directly involved in fatty acid synthesis) were found to be considerably higher in WAT of MFR rats refed for 3 days in comparison to control rats, and remained elevated even after 12 days of refeeding. These observations suggest that the elevation of lipogenic enzyme activities induced by multiple cycles of dietary deprivation followed by refeeding persists for several days, markedly increasing the lipogenic capacity of adipose tissue, which, accompanied by a decrease in circulating leptin levels, may promote weight gain.

Adipose Tissue, White↗
PubMed1994

Characterization of the nutritional interactions between organic acids and inorganic bases in the pig and chick.

Four experiments were conducted to characterize the interactions between fumaric (FA), malic (MA), or citric acid (CA) and NaHCO3. In two experiments, seven diets were formulated containing 2.5% FA, MA, and CA, with or without 2.3, 1.9, or 1.4% NaHCO3, respectively, as well as a control diet (no addition of organic acids or NaHCO3) for 28-d-old pigs (Exp. 1, corn-soy protein concentrate-based diet) and 1-wk-old chicks (Exp. 4, corn-soy-based diet). In Exp. 1, at 2 and 4 wk, the FA+NaHCO3 treatment resulted in greater average daily gain (ADG) and feed intake (ADFI) compared with the control (P < .05). In Exp. 2, 28-d-old pigs were fed corn-soy diets with .9, 1.6, and 2.3% NaHCO3 in addition to 2.5% FA. After wk 2, there was a quadratic response in ADG (P < .08) and ADFI (P < .05) when increasing levels of NaHCO3 were added to the diet. This was true at wk 4 for both ADG and ADFI (P < .05). In Exp. 3, finishing pigs were fed corn-soy diets containing 2.5% FA or 2.5% FA + 2.3% NaHCO3 added to a control diet. No effect (P < .05) of FA or NaHCO3 was observed. In Exp. 4, the combination of CA+NaHCO3 or MA+NaHCO3 was superior to FA+NaHCO3 for ADG (P < .08) and ADFI (P < .05) when fed to young chicks.

Animal Feed↗
PubMed1964

THE GENUS VEILLONELLA. I. GENERAL CULTURAL, ECOLOGICAL, AND BIOCHEMICAL CONSIDERATIONS.

Rogosa, M. (National Institutes of Health, Bethesda, Md.). The genus Veillonella. I. General cultural, ecological, and biochemical considerations. J. Bacteriol. 87:162-170. 1964.-Arguments are presented for excluding Veillonella discoides, V. reniformis, V. orbiculus, and V. vulvovaginitidis from the genus, and for restricting it to aerogenic organisms such as V. parvula and V. alcalescens. The genus Veillonella thus would comprise species which are anaerobic and nonmotile; are small, spherical, gram-negative cocci appearing as pairs, masses, and short chains; and are cytochrome-oxidase- and benzidine-negative. Veillonella would be further characterized in that glucose or any other carbohydrate is not fermented; indole is not produced; gelatin is not liquefied; nitrate is reduced; H(2)S is produced; propionic and acetic acids, CO(2), and H(2) are produced from lactate during growth; and pyruvic, oxaloacetic, malic, fumaric, and succinic acids are metabolized by resting cells, but citric, isocitric, and malonic acids are not. In addition to the above, a number of cultural, ecological, and biochemical characteristics are described. At present, V. parvula (the type species) and V. alcalescens would be retained as valid species. Errors in the descriptions of V. parvula and V. alcalescens are corrected by amended statements. These species are differentiated serologically. Also, V. alcalescens differs from V. parvula in having an absolute requirement for putrescine or cadaverine and in decomposing H(2)O(2).

Cadaverine↗
PubMed2006

[Determination of organic acids in cane vinasse by micellar electrokinetic capillary chromatography with indirect ultraviolet detection].

Micellar electrokinetic capillary chromatography (MECC) with indirect ultraviolet (UV) detection method for the separation and determination of several organic acids in cane vinasse, including malonic, formic, tartaric, malic, succinic, glutaric, acetic, lactic and glutamic acids, were developed. Electrophoretic conditions were as follows: uncoated fused silica capillary (56 cm/ 64 cm (effective/total length), 50 microm i. d. ), 7.5 mmol/L potassium acid phthalate-1. 5 mmol/L cetyltrimethyl-ammonium bromide (CTAB) at pH = 6.50 as buffer solution, applied voltage -25 kV, temperature 25 degrees C, detection wavelength 300 nm, reference wavelength 210 nm. Good linearities were obtained for nine organic acids, and the detection limits were 0.5 mg/L, 0.3 mg/L, 1.5 mg/L, 1.5 mg/L, 0.3 mg/L, 0.3 mg/L, 0.4 mg/L, 0.4 mg/L, 0.4 mg/L for malonic, formic, tartaric, malic, succinic, glutaric, acetic, lactic and glutamic acid, respectively. The relative standard deviations (RSDs) for migration times and peak areas of nine organic acids within a day were 0.4% - 0.6% and 2.3% - 4.8%, respectively. The corresponding data for five days were 0.5% -0.7% and 3.3% - 5.2%. The recoveries of acid standards were above 93%. The method can be applied to determine the organic acids in cane vinasse with satisfactory results.

Acids↗
PubMed2001

Effect of ion-exchange site and eluent modifiers on the anion-exchange of carboxylic acids.

The chromatographic behavior of carboxylic acids has been investigated, on three different latex-based anion-exchange columns, in order to define the effect of the ion-exchange site structure on selectivity. The analytical columns produced are characterized by alkyl amines containing zero, one or two hydroxyl groups on the anion-exchange functional site. Divalent carboxylic acids, namely fumaric, maleic, trans-beta-hydromuconic, trans,trans-muconic, oxalic, malonic, succinic, glutaric, adipic, malic, tartaric and mucic acids, have been chosen as test solutes. The performance of the three stationary phases has been studied employing NaOH eluents and has been discussed with respect to the different hydrophilicity of the ion-exchange sites and analytes. Considering on previous results obtained using organic solvents (methanol and acetonitrile) with carbonate eluents on a highly hydrophilic column, the performance of the three exchangers has also been studied using acetonitrile, methanol and n-propanol. The chromatographic behavior was similar for the three columns studied, but the different organic solvents gave variations in selectivity. In order to characterize these differences, particle size measurements of the latices were performed both in pure water and in the presence of each organic solvent studied.

Anion Exchange Resins↗
PubMed2003

Effect of organic acids and hydrogen peroxide on Cryptosporidium parvum viability in fruit juices.

Cryptosporidium parvum has historically been associated with waterborne outbreaks of diarrheal illness. Foodborne cryptosporidiosis has been associated with unpasteurized apple cider. Infectious oocysts are shed in the feces of common ruminants like cattle and deer in and near orchards. In this study, the ability of organic acids and hydrogen peroxide (H2O2) added to fruit juice to inhibit the survival of C. parvum was analyzed. Oocyst viability was analyzed by a cell culture infectivity assay with the use of a human ileocecal cell line (HCT-8) whose infectivity pattern is similar to that for human oral infectivity. Cell monolayers were infected with 10(6) treated oocysts or a series of 10-fold dilutions. Parasitic life stages were visualized through immunohistochemistry with 100 microscope fields per monolayer being counted. In vitro excystation assays were also used to evaluate these treatments. Organic acids and H2O2 were added to apple cider, orange juice, and grape juices on a weight/volume basis. Malic, citric, and tartaric acids at concentrations of 1 to 5% inhibited C. parvum's infectivity of HCT-8 cells by up to 88%. Concentrations ranging from 0.025 to 3% H2O2 were evaluated. The addition of 0.025% H2O2 to each juice resulted in a >5-log reduction of C. parvum infectivity as determined with a most-probable-number-based cell culture infectivity assay. As observed with differential interference contrast and scanning electron microscopy, reduced infectivity may be mediated through effects on the oocyst wall that are caused by the action of H2O2 or related oxygen radicals. The addition of low concentrations of H2O2 can represent a valuable alternative to pasteurization.

Animals↗
PubMed1988

[The structuro-functional state of the ischemic myocardium under the action of a terrilitin-nicotinic acid mixture in animal experiments].

Histochemical evidence of the activity and distribution of glycolysis redox enzymes, tissue respiration and terminal oxidation pattern (dehydrogenase of lactic, malic, succinic and isocitric acids, NAD-N- and NADPh-N-ase, cytochrome oxidase) as well as the levels of the major carbohydrates (glycogen, neutral aminopolysaccharides, glucose) were experimentally studied in the cardiomyocytes of myocardial necrotic, perinecrotic and intact areas in the control and in the experimental material under the administration of terrilitin-nicotinic acid mixture. It was stated that the use of aforementioned mixture contributed to the retention of enzymatic activity and optimal levels of energy formation in the cardiomyocytes of the marginal infarction zone and noticeably prevented the destructive involvement of the considered area as well as the impairment of functional activity of oscillating cardiomyocytes. Therefore, the application of the mixture improved the outcome prognosis in acute myocardial infarction.

Amylases↗
PubMed1984

The distribution of six enzymes of oxidative metabolism along the rat nephron.

Using quantitative methods, citrate synthase (CS), fumarase, beta-hydroxyacyl-coenzyme A (CoA) dehydrogenase (beta OAC), 3-keto-acid CoA transferase (KCT), malic dehydrogenase (MDH), and malic enzyme were measured in seven defined parts of the nephron and in thin limb and papilla areas dissected from freeze-dried microtome sections of rat kidney. The results not only show a wide range of activity along the nephron for each of the enzymes, but that the proportions between the enzymes vary markedly among the different parts of the nephron. This suggests the existence of major regional differences in the capacity to oxidize specific metabolites. The ratio between two citrate cycle enzymes, fumarase and CS, was 4- or 5-fold higher in proximal segments than in the glomerulus or thin limb areas. The ratio between beta OAC (an enzyme of fatty acid oxidation) and CS was 3- to 5-fold higher in the middle proximal segments than in glomeruli or thin limb and papilla areas. The key enzyme for ketone body metabolism, KCT, was essentially confined to the thick tubule segments. Malic enzyme, in contrast to the other five enzymes, was highest in the proximal straight segments. New methods, sufficiently sensitive for this histochemical study, are described for malic enzyme and 3-keto-acid CoA transferase.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1986

Biochemical changes in liver and blood during liver fattening in rats.

Excessive fat accumulation in the liver is a common metabolic disorder seen in humans and animals. Fatty liver was induced in the rat by feeding the animals with a sucrose rich diet containing 1% orotic acid for 2-3 weeks. In the sera from fatty liver rats there were significant changes in the level of alanine aminotransferase (+ 68.7%), malic dehydrogenase (+ 77.8%), gamma-glutamyl transpeptidase (- 53.4%) and total lipids (+ 26.6%). There were small to no changes in the levels of aspartate aminotransferase, glucose-6-phosphate dehydrogenase, lactic dehydrogenase, aldolase, malic enzyme, 6-phosphogluconic acid dehydrogenase, alkaline phosphatase and albumin. In fatty liver, significant differences were seen in the levels of glucose 6-phosphate dehydrogenase (+ 235%), malic enzyme (+ 170%), gamma-glutamyl transpeptidase (+ 113%), 6-phosphogluconate dehydrogenase (+ 63%), aspartate aminotransferase (+ 35.6%), malic dehydrogenase (+ 38%), lactic dehydrogenase (+ 37%), and alanine aminotransferase (- 23%). Comparison of the non-fatty part with the fatty part of the fatty liver showed larger changes in the non-fatty part of the liver, suggesting that during the fattening process, there is an induction of enzymes in the liver reaching a peak prior to lipid accumulation, declining thereafter during liver fattening. The increase in NADPH-generating lipogenic enzymes suggests that accumulated fat in the liver is at least partially from de-novo increased synthesis in the liver.

Animals↗
PubMed2006

Thermodynamic models of aqueous solutions containing inorganic electrolytes and dicarboxylic acids at 298.15 K. 1. The acids as nondissociating components.

Atmospheric aerosols contain a significant fraction of water-soluble organic compounds, including dicarboxylic acids. Water activities at approximately 298.15 K (including data for highly supersaturated solutions) of oxalic, malonic, succinic, glutaric, maleic, malic, and methyl succinic acids are first correlated as a function of concentration, treating the acids as nondissociating components. Methods proposed by Clegg et al. (J. Aerosol. Sci. 2001, 32, 713-738), and by Clegg and Seinfeld (J. Phys. Chem. A 2004, 108, 1008-1017) for estimating water activities and solute activity coefficients in aqueous mixtures containing both electrolytes and uncharged solutes are then evaluated from comparisons with literature data. These data include water activities, solubilities, and determinations of the eutonic points of solutions containing up to five acids, and solutions containing one or more acids and the salts (NH(4))(2)SO(4), NH(4)NO(3), or NaCl. The extended Zdanovskii-Stokes-Robinson approach of Clegg and Seinfeld yields the more accurate predictions for aqueous mixtures containing dicarboxylic acids only, and for aqueous mixtures of the acids and salts (though by a lesser margin). A number of hybrid modeling approaches, which contain elements of both methods, are outlined.

Ammonium Sulfate↗
PubMed2003

Analysis of carboxylic acid metabolites from the tricarboxylic acid cycle in Bacillus subtilis cell extract by capillary electrophoresis using an indirect photometric detection method.

With a growing interest in metabolome analysis, there is a need for developing robust methods for analysis of intracellular metabolites profiles in real samples like e.g., bacteria cell. Due to their weak absorbance properties, tri- and dicarboxylic acids from TCA cycle (citric, isocitric, 2-oxoglutaric, succinic, fumaric, malic) as well as carboxylic acid metabolites from glycolysis pathway, urea cycle and metabolism of amino compounds (formic, pyruvic, lactic, acetic, glutamic) were analyzed by capillary electrophoresis (CE) with indirect UV detection. Using 4 mM 2,6-pyridinedicarboxylic acid as a highly UV absorbing carrier electrolyte, 0.2 mM cetyltrimethylammonium bromide, 10% ethylene glycol and 10% acetonitrile, pH 3.5, carboxylic acids metabolites were analyzed in Bacillus subtilis cell extract from two different cultures: glucose and malate. CE with an electrokinetic injection mode achieved limits of detection in the range of 13-54 ppb (1.12-10(-7) - 5.96-10(-7) M). The reproducibility and linearity of method was investigated with RSD for migration time less than 1.3% and acceptable correlation coefficients. The optimized CE method was used to compare metabolome content of cell extract derived from two different culture media containing either glucose or malate as a carbon source. The changes in carboxylic acid metabolites profile were observed depending from used culture medium. Carboxylic acid concentrations ranged: in cell extract from malate culture from 59 to 0.5 microM for lactate and citrate, respectively, and in cell extract from glucose culture from 133 to 0.5 microM for glutamate and citrate, respectively. Appropriate concentrations of carboxylic acid in the single bacterium cell were estimated at mM and sub-mM levels.

Bacillus subtilis↗
PubMed1996

Regulation of gene expression and activity of malic enzyme in liver of hereditary hypertriglyceridemic (hHTG) insulin resistant rat: effect of dietary sucrose and marine fish oil.

The effect of increased dietary intake of n-3 polyunsaturated fatty acids (PUFA) on hepatic malic enzyme (EC 1.1.1.40) gene expression and activity was investigated in either hereditary fixed or dietary induced hypertriglyceridemia after euglycemic hyperinsulinemic (6.4 mU/kg/min) clamp. The hereditary hypertriglyceridemic rats (hHTG) were fed for 2 weeks basal (B) or high (63 cal %) sucrose (HS) diet, with or without fish oil (FO, 30 wt % n-3 PUFA). The results were compared with the data obtained in control (C) animals subjected to identical protocol. In hHTG rats, increased gene expression [hHTG: 1.7 +/- 0.1 vs. C: 0.5 +/- 0.05 arbitrary units (AU), P<0.02] for malic enzyme (ME) was not accompanied by increased activity of this enzyme in liver [hHTG: 1.1 +/- 0.1 vs. C: 3.1 +/- 0.4 nkat/mg, P<0.001]. HS feeding raised the activity [HS-hHTG: 4.2 +/- 0.3 nkat/mg, P<0.001; HS-C: 7.5 +/- 0.9 nkat/mg, P<0.001] and mRNA levels [HS-hHTG: 10.4 +/- 0.3 AU, P<0.001; HS-C: 7.7 +/- 0.3 AU, P<0.001] in liver of both hHTG and control rats. The supplementation of HS diet with FO led to striking suppression of activity by 63 % [2.8 +/- 0.5 nkat/mg, P<0.001] and gene expression [2.9 +/- 0.2 AU, P<0.001] for ME in liver of control rats. Such inhibitory effect was not as pronounced in hHTG rats and reached about 50 % in the ME activity [HS+FO: 2.0 +/- 0.06 nkat/mg vs. HS:4.2 +/- 0.3 nkat/mg, P<0.001] or 30 % decrease in ME mRNA levels [HS+FO: 7.5 +/- 0.8 Au vs. HS:10.4 +/- 0.3 AU, P<0.001]. Thus, hHTG rats have markedly elevated levels of mRNA for malic enzyme in liver accompanied by decreased enzymatic activity. Dietary manipulations leading to alteration of hypertriglyceridemia (HS diet, omega-3 PUFA) influenced both the activity of malic enzyme and its transcription in the liver.

Journal Article↗