PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “CITRIC 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 505 records · Page 28Linked to original sources
PubMed1989

Activities of pyruvate dehydrogenase, enzymes of citric acid cycle, and aminotransferases in the subcellular fractions of cerebral cortex in normal and hyperammonemic rats.

Activity levels of pyruvate dehydrogenase, enzymes of citric acid cycle, aspartate and alanine aminotransferases were estimated in mitochondria, synaptosomes and cytosol isolated from brains of normal rats and those injected with acute and subacute doses of ammonium acetate. In mitochondria isolated from animals treated with acute dose of ammonium acetate, there was an elevation in the activities of pyruvate, isocitrate and succinate dehydrogenases while the activities of malate dehydrogenase (malate----oxaloacetate), aspartate and alanine aminotransferases were suppressed. In subacute conditions a similar profile of change was noticed excepting that there was an elevation in the activity of alpha-ketoglutarate dehydrogenase in mitochondria. In the synaptosomes isolated from animals administered with acute dose of ammonium acetate, there was an increase in the activities of pyruvate, isocitrate, alpha-ketoglutarate and succinate dehydrogenases while the changes in the activities of malate dehydrogenase, aspartate and alanine amino transferases were suppressed. In the subacute toxicity similar changes were observed in this fraction except that the activity of malate dehydrogenase (oxaloacetate----malate) was enhanced. In the cytosol, pyruvate dehydrogenase and other enzymes of citric acid cycle except malate dehydrogenase were enhanced in both acute and subacute ammonia toxicity though their activities are lesser than that of mitochondria. In this fraction malate dehydrogenase (oxaloacetate----malate) was enhanced while activities of malate dehydrogenase (malate----oxaloacetate), aspartate and alanine aminotransferases were suppressed in both the conditions. Based on these results it is concluded that the decreased activities of malate dehydrogenase (malate----oxaloacetate) in mitochondria and of aspartate aminotransferase in mitochondria and cytosol may be responsible for the disruption of malate-aspartate shuttle in hyperammonemic state.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1986

The effectiveness of citric acid as an adjunct to surgical re-attachment procedures in humans.

The purpose of this study was to clinically evaluate the effect of citric acid on re-attachment and re-adaptation in conjunction with periodontal surgery. A split-mouth design was used in 10 patients involving 30 quadrants of surgery. A total of 120 teeth were treated. Each quadrant consisted of at least 2 teeth from cuspid to second molar. One quadrant was treated with a modified Widman flap alone while the root surfaces of the contralateral side were also treated with a 3 min application of citric acid. Immediately following hygienic phase and at 3 and 6 months postsurgically, the following measurements were taken in this sequence: gingival index, gingival crevicular fluid flow, plaque index, furcation involvement, level of attachment and probing depth. All the data were statistically analyzed using the paired t-test, chi 2 and Fisher exact probability test. The biometric results showed that both surgical techniques resulted in a loss of attachment in shallow pockets and a gain in deeper pockets. Both techniques resulted in similar amounts of recession and probing depth reduction at 6 months. Gingival index, plaque index and furcation values decreased at 3 and 6 months postsurgically. The gingival crevicular fluid values remained essentially the same up to 6 months postsurgically.

Adult↗
PubMed2004

Effect of three different time periods of irrigation with EDTA-T, EDTA, and citric acid on smear layer removal.

OBJECTIVE: An in vitro study was conducted to evaluate the effect of EDTA-T, 17% EDTA, and 10% citric acid on the removal of smear layer from root canal dentin after final irrigation for 3, 10, and 15 min. STUDY DESIGN: Root canals of 90 extracted human canines were divided into 9 groups of 10 teeth; each group received a final irrigation with one of the irrigants for the established time intervals. After irrigation, the teeth were split and prepared for SEM analysis to determine the number of open dentinal tubules. RESULTS: There were statistically significant better results (P <.05) when irrigation with 10% citric acid for 3 min was compared to 10 and 15 min, and when irrigation with EDTA for 3 min was compared to 15 min. In all cases, irrigation for 3 min presented the greatest number of open dentinal tubules. There were no significant differences (P>.05) for the 3 time intervals of irrigation for EDTA-T, although there were a greater number of open tubules at 3 min. CONCLUSION: These 3 irrigants were effective at the shortest time tested and did not demonstrate an improved effect with an increase in time.

Citric Acid↗
PubMed1984

A histometric evaluation of the effect of citric acid preparation upon healing of coronally positioned flaps in nonhuman primates.

Facial recession defects were created on maxillary canine teeth of six Macaca irus monkeys and left untreated and exposed to oral fluids for 6 to 12 weeks. Notches were placed in the exposed root surfaces at the level of the free gingival margins. Following root planing with the addition of topical citric acid application on experimental surfaces, pedicle flaps were coronally positioned over the previously exposed roots. After euthanasia, block sections representing postsurgical time periods of 0, 3, 7, 14, 21, 28 and 42 days were secured and tissues were processed for histologic evaluation. All citric acid-treated surfaces exhibited new connective tissue attachment of pedicle flaps to previously exposed areas by 14 days with transmission electron micrographs confirming beginning cementum deposition. In contrast, controls demonstrated epithelial migration to, or apical to, reference notches. Although the total number of samples available for statistical comparison was small, a two-tailed t test for correlated samples showed citric acid application did not result in enhanced clinical root coverage, but did result in significantly greater amounts of new connective tissue attachment (P less than 0.05, df = 3). Pedicle flap healing against teeth with devital pulps was identical to that seen in teeth with vital pulps, while citric acid application to root-planed surfaces of vital teeth had no observable effect upon pulpal tissues.

Animals↗
PubMed1992

ATP-citrate lyase as a target for hypolipidemic intervention. Sulfoximine and 3-hydroxy-beta-lactam containing analogues of citric acid as potential tight-binding inhibitors.

Citric acid analogues (+/-)-12a,b and (+/-)-17a,b, where one of the primary carboxylates has been replaced by a sulfoximinoyl and a 3-(3-hydroxy-beta-lactamyl) moiety, respectively, have been synthesized and evaluated as inhibitors of ATP-citrate lyase. The design of these inhibitors was based on methionine sulfoximine and tabtoxinine beta-lactam, potent, tight-binding inhibitors of glutamine synthetase. Both ATP-citrate lyase and glutamine synthetase employ phosphate-carboxylate anhydrides as a method for carboxylate activation during catalysis. Only one diastereomer, (+/-)-12a, displayed weak, reversible inhibition, while the remaining citrate analogues (+/-)-12b and (+/-)-17a,b were inactive against the lyase. No time-dependent inactivation of the enzyme was observed.

ATP Citrate (pro-S)-Lyase↗
PubMed1978

Human pulpal response to citric acid cavity cleanser.

Treatment of cavities with citric acid cavity cleanser, also used as an etchant, before restoration with zinc oxide-eugenol cement, was toxic to the human dental pulp in comparison to sham-treated controls. The cleanser caused a significantly (P less than .01) greater intensity and incidence (P less than .01) of inflammation. The added insult from cleanser pretreatment caused destruction of the odontoblast processes withnin the cut dentinal tubules, and an increase in diameter of the tubules. These effects on dentin and odontoblasts probably contributed to the observed increase in adverse pulp responses.

Adolescent↗
PubMed1993

Contents of fructose, citric acid, acid phosphatase, proteins and electrolytes in secretions of the accessory sex glands of the male golden hamster.

Secretions were collected from the ampullary gland, dorsolateral prostate, ventral prostate, coagulating glands and seminal vesicles of male golden hamsters aged 15-20 weeks. The concentrations of total protein, citric acid, fructose, acid phosphatase, chloride, sodium, potassium, calcium, magnesium and zinc were determined. The ampullary gland secreted predominantly citric acid, sodium and acid phosphatase. Zinc was secreted only by the prostatic complex, with the largest quantity coming from the coagulating gland. The highest concentrations of potassium, calcium and magnesium were found in secretions of the ventral prostate. The coagulating gland and dorsolateral prostate were the principal contributors to total protein. The hamster appears to be more related to the mouse than to the rat in terms of the secretory functions of its accessory sex glands.

Acid Phosphatase↗
PubMed1995

The effect of inhaled and oral dextromethorphan on citric acid induced cough in man.

1. Dextromethorphan is a widely used antitussive agent which is a non-narcotic codeine analogue. We have investigated whether inhaled administration of dextromethorphan provides antitussive activity in a citric acid induced cough model. 2. Twenty normal subjects underwent repeated cough challenge with 5% citric acid. Subjects were studied on six occasions. Study medication consisted of oral dextromethorphan 30 mg or oral matched placebo or 1, 3 and 30 mg inhaled dextromethorphan or matched inhaled placebo. Cough challenge was administered 10 min after study medication and hourly thereafter up to 250 min. 3. No significant differences were seen between baseline cough responses. Oral dextromethorphan (30 mg) produced a mean percentage reduction in cough of 38% (P < 0.002), which remained significant at 250 min. Inhaled dextromethorphan had no clinically significant effect although activity at later time points was not excluded. The antitussive effect of oral dextromethorphan is confirmed with prolonged inhibition of induced cough. It is possible that dextromethorphan or its active metabolites act centrally to inhibit the cough reflex.

Administration, Inhalation↗
PubMed2005

Safety and efficacy evaluation of aqueous citric acid to degrade B-aflatoxins in maize.

Chemical inactivation of aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) in maize grain by means of 1N aqueous citric acid was confirmed by the AFLATEST immunoaffinity column method, high performance liquid chromatography (HPLC), and the Ames test (Salmonella-microsomal screening system). The AFLATEST assay showed that aflatoxins in the maize grain with an initial concentration of 29 ng/g were completely degraded and 96.7% degradation occurred in maize contaminated with 93 ng/g when treated with the aqueous citric acid. Aflatoxin fluorescence strength of acidified samples was much weaker than untreated samples as observed in HPLC chromatograms. On the other hand, the Ames test results indicated that the mutagenic activity of acidified samples was greatly reduced compared with that of untreated samples based on his- --> his+ reversions in the Salmonella TA100 strain. Chemical inactivation appears to be a promising method of removing aflatoxin from food commodities.

Aflatoxin B1↗
PubMed1992

The effect of pH on the thermal resistance of Clostridium sporogenes (PA 3679) in asparagus purée acidified with citric acid and glucono-delta-lactone.

The influence of type of acid, pH and temperature on heat resistance of Clostridium sporogenes (PA 3679) spores were investigated in white asparagus pureé acidified with citric acid and glucono-delta-lactone (GDL). The pH values studied were: 4.5, 4.8, 5.1 and 5.4 at temperatures of 110, 115, 118 and 121 degrees C. The addition of citric acid and GDL to reduce pH significantly diminished heat resistance of the spores. The two acids investigated differed in their effect on heat resistance at the various pH-levels. The most pronounced effect was observed at the lower heat treatment temperatures investigated. The z values ranged from 10.24 to 13.09 degrees C in the asparagus purée with acids added and with significant differences between the two acids and the various pH levels.

Citrates↗
PubMed1966

Enzymes in glycolysis and the citric acid cycle in the yeast and mycelial forms of Paracoccidioides brasiliensis.

Kanetsuna, Fuminori (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela), and Luis M. Carbonell. Enzymes in glycolysis and the citric acid cycle in the yeast and mycelial forms of Paracoccidioides brasiliensis. J. Bacteriol. 92:1315-1320. 1966.-Enzymatic activities in glycolysis, the hexose monophosphate shunt, and the citric acid cycle in cell-free extracts of the yeast and mycelial forms of Paracoccidioides brasiliensis were examined comparatively. Both forms have the enzymes of these pathways. Activities of glucose-6-phosphate dehydrogenase and malic dehydrogenase of the mycelial form were higher than those of the yeast form. Another 15 enzymatic activities of the mycelial form were lower than those of the yeast form. The activity of glyceraldehyde-3-phosphate dehydrogenase showed the most marked difference between the two forms, its activity in the mycelial form being about 20% of that in the yeast form.

Blastomyces↗
PubMed1976

Coordination of citric acid cycle activity with electron transport flux.

Feedback control between flux through the phosphorylating electron transport chain and the coordination of flux through individual steps of the citric acid cycle have been investigated under a number of different conditions of substrate availability and workloads in the isolated perfused rat heart. The transition from substrate-free perfusion to perfusion with glucose and insulin with no change of workload was associated with increases in the pool sizes of citric acid cycle intermediates except for oxaloacetate, but with an initial imbalance of flux through individual steps in the cycle and transport of anions of the malate-aspartate cycle across the mitochondrial membrane. Flux through citrate synthase initially increased while that through alpha-ketoglutarate dehydrogenase decreased. Of the components of the malate-aspartate cycle, flux through the malate-alpha-ketoglutarate exchange was increased prior to that through the glutamate-aspartate exchange and intramitochondrial aspartate aminotransferase. These changes can be accounted for on the basis of known kinetic controls of the enzyme and transport steps in response to increased pyruvate, acetyl-CoA, and NADH delivery at an approximately constant rate of ATP turnover.

Adenine Nucleotides↗
PubMed1995

Effect of the two tachykinin antagonists, SR 48968 and SR 140333, on cough induced by citric acid in the unanaesthetized guinea pig.

It is now well-established that sensory nerves stimulation in the airway induces bronchoconstriction and inflammation, but also protective reflexes, such as coughing. These effects are mediated through the release of tachykinins (substance P and neurokinin A) and we have recently shown that SR 48968, a tachykinin NK2-receptor antagonist, inhibited cough induced by citric acid. In this paper, we have studied the effects of SR 48968 administered by aerosol. We have also investigated the effects of SR 140333, a tachykinin NK1-receptor antagonist, and the combination of both SR 48968 and SR140333 to determine whether tachykinin NK1 receptors are involved in cough. Finally, we have studied the combined effects of SR 48968 and salbutamol to find out whether the antitussive effect of SR 48968 is a consequence of the inhibition of bronchoconstriction. Unanaesthetized guinea-pigs were placed in a transparent chamber and exposed to an aerosol of citric acid (0.4 M). The number of coughs was counted by visual inspection and by determination of sounds and pressure variations in the chamber. By the aerosol route, SR 48968 was an efficient antitussive and 16 times more potent than codeine. SR 140333 (0.1-1 mg.kg-1 i.p.) did not exert any antitussive effect but it potentiated the maximal effect induced by SR 48968. Finally, salbutamol, in a dose (0.3 mg.kg-1) which inhibits bronchoconstriction, but not cough induced by citric acid, did not modify the antitussive effect of SR 48968.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1987

Molecular genetic aspects of the citric acid cycle of Escherichia coli.

The genes encoding all of the citric acid cycle enzymes of Escherichia coli have been cloned and much has been learned about the structure, function and expression of these enzymes from the nucleotide sequences, the mRNA transcripts and site-directed mutagenesis of the corresponding genes. Special features of the expression of the aerobic cycle, and its anaerobic transformation into a branched pathway in a facultative anaerobe, are considered. Aspects of the structure-function relationships of succinate dehydrogenase, succinyl-CoA synthetase, fumarase and related enzymes, and the 2-oxo acid dehydrogenase complexes are reviewed.

Citric Acid Cycle↗
PubMed1984

The production of a root surface smear layer by instrumentation and its removal by citric acid.

The purpose of this study was to characterize, using the scanning electron microscope, the nature of root surfaces denuded by (1) root planing alone or (2) root planing plus citric acid treatment. Six teeth were extracted from three squirrel monkeys, and the coronal half of the root surface was planed to remove attached periodontal ligament fibers and cementum. Citric acid, pH 1, was topically applied to the denuded surfaces of 3 teeth. The surface of only root-planed specimens had an irregular surface which corresponded to a smear layer. Root surfaces that had received acid treatment after root planing exhibited funnel-shaped orifices of dentinal tubules, and intertubular zones with a fibrillar, mat-like morphology. The implications of the different root-surface characteristics are discussed.

Administration, Topical↗
PubMed1992

Inhibition of aluminium toxicity by magnesium and citric acid in tobacco tissue culture.

Using tobacco callus tissues the authors studied the antagonism of magnesium and aluminium, and the inhibition of aluminium toxicity by magnesium and citric acid, as expressed by their effect on growth and alkalod content. In response to an increase in the concentration of MgSO4 in the culture medium the fresh weight of the cultures significantly increased, while with an increase in Al2(SO4)3 growth decreased, 2 mM causing a high degree of inhibition. The toxic effect of aluminium was less marked when Mg was present at a concentration higher by an order (antagonistic inhibition). When citric acid was added to the culture medium, promoting complex formation with Al, the toxic effect of Al was not apparent. The nicotine content of the tissues was in each case inversely correlated with the magnitude of biomass formation.

Alkaloids↗
PubMed2005

Dendrimers of citric acid and poly (ethylene glycol) as the new drug-delivery agents.

Citric acid-polyethylene glycol-citric acid (CPEGC) triblock dendrimers as biocompatible compounds containing G(1), G(2) and G(3) were applied as the drug-delivery systems. Some of the small size molecules and drugs are trapped with the above-synthesized dendrimers. The guest molecules, which are hydrophobic when trapped into the suitable sites of dendrimers, are becoming soluble in aqueous solution. The quantity of trapped molecules and drugs such as 5-amino salicylic acid (5-ASA), pyridine, mefenamic acid, and diclofenac was measured. The drug/dendrimer complexes remained in room temperature for about 10 months and after this long time they were stable and the drugs were not released. Also, the controlled release of the above-mentioned molecules and drugs in vitro conditions was investigated. The structure definition and controlled release of the molecules and drugs were carried out using different spectroscopy methods.

Biocompatible Materials↗