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PubMed2001

Interaction of Cd and citric acid, EDTA in red soil.

Adsorption and desorption process of cadmium in red soil (Ferrisols) as well as the influence by media's pH were investigated in detail with and without citric acid and EDTA. Experimental results clearly showed that Cd adsorption in red soil was affected significantly by the coexisted organic chemicals. In the presence of citric acid and EDTA, Cd adsorption in red soil increased with pH in acid media but decreased in high pH one. Further studies placed stress on the adsorbed Cd in red soil which was found to be existed mainly as exchangeable one at pH < 5.5, and desorption rate by 0.10 mol/L NaNO3 gave a peak-shaped curve due to the difference of specifically and nonspecifically adsorbed Cd with pH's change.

Adsorption↗
PubMed1976

Preparation and properties of solid dispersion system containing citric acid and primidone.

Solid dispersions containing 1--32% (w/w) primidone were prepared by fusing the drug with citric acid and rapidly cooling the melt. The solidified dispersions were clear glasses which devitrified on aging or when stored at 60 degrees for up to 3 days. The phase diagram of the devitrified system indicated that the drug may exist as a solid solution at 1--3% (w/w) concentrations but that a eutectic mixture is formed at higher concentrations. The solubility of primidone increased in the presence of citric acid. Preliminary dissolution studies showed that the dissolution rate from the solid dispersion was greater than that of the pure drug or the physical mixture.

Chemical Phenomena↗
PubMed1988

Cough threshold to citric acid in diabetic patients with and without autonomic neuropathy.

The cough reflex has been investigated in insulin dependent diabetic patients with and without autonomic neuropathy. The cough response to inhaled citric acid was determined in eight patients with diabetes who had severe autonomic neuropathy and compared with that in 10 who had no evidence of neuropathy. The patients with autonomic neuropathy had a higher median threshold for the cough response to citric acid (median 50%, range 20- greater than 100%) than non-neuropathic control patients (median 10%, range 2-20%). These results suggest that vagal innervation of the bronchial tree is damaged by diabetic autonomic neuropathy.

Adult↗
PubMed1989

Cell and fiber responses to cementum from periodontitis-affected root surfaces after citric acid treatment.

The purpose of this study was to assess connective tissue and epithelial responses to periodontitis-affected cementum (from exposed roots of human teeth) after surface demineralization with citric acid. Cementum specimens were obtained from root surfaces covered by calculus. Each rectangular specimen had a face of cementum and an opposite surface composed of pulpal dentin. One half of the specimens were treated with citric acid (experimental group), while the remainder served as untreated control specimens. Specimens were implanted vertically into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. 4 specimens in each group were available for examination 1, 3, 5, and 10 days after implantation. Histologic and histometric analyses of the implants included counts of adhering cells, evaluation of attached connective tissue fiber density and diameter, and assessment of epithelial migration. At 1 day, a distinct zone of surface demineralization was not present on the surface of the cementum in the experimental group, although such a zone was present on the dentin surfaces of the same specimens. Histometric comparisons between experimental and control groups at 1 day showed no differences in cell attachment or length of cementum surface within connective tissue. By 10 days, there was a trend for greater cell attachment to demineralized cementum, but the differences were not statistically significant. Although connective tissue fiber attachment has been shown to occur to demineralized dentin and to normal cementum in this model system, fiber attachment did not occur to the cementum in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Citric acid treatment of severe electric burns complicated by multiple antibiotic resistant Pseudomonas aeruginosa.

A case of severe electric burns complicated by multiple antibiotic resistant Pseudomonas aeruginosa not responding to various antibiotics administered systemically is presented. Citric acid (3%) was used successfully to eliminate Pseudomonas aeruginosa from burn wounds and infection was completely controlled in 14 days. Citric acid treatment is evidently of value in the clinical control of burn wound colonization caused by difficult strains of Pseudomonas aeruginosa.

Administration, Topical↗
PubMed1987

Effect of citric acid and various concentrations of fibronectin on healing following periodontal flap surgery in dogs.

The purpose of this histologic and histometric study was to examine the effect of citric acid and increasing concentrations of fibronectin on new connective tissue attachment following periodontal flap surgery. Full thickness, mucoperiosteal flaps were elevated in six healthy mongrel dogs. Two to 3 mm of alveolar bone were removed along the buccal aspect of the teeth in the mandible and into the interproximal areas of each surgical site. Cementum was removed from the exposed root surfaces and reference notches were inscribed into the roots at the margin of the recontoured bone. Citric acid, pH 1.0, was applied to the instrumented root surfaces for 3 minutes and rinsed with sterile saline. Both the root surfaces and the inner surface of the flap were then bathed in either sterile saline or increasing concentrations (0.38, 0.75 and 1.5 mg/ml saline) or exogenous fibronectin. All the flaps were returned to their original preoperative positions, secured using figure 8 sutures with 4-0 braided silk and allowed to heal. Two dogs per time-point were sacrificed at 1, 2 and 6 weeks after surgery. Block specimens of the surgical sites were demineralized and serial sections prepared for histologic and histometric evaluations. Histologically, tissue sections were examined for: (1) epithelial proliferation and attachment, (2) periodontal fiber organization and maturation, (3) inflammatory cell types, (4) presence or absence of new cementum deposition and (5) degree of vascularity of the tissues. Histometric measurements were taken: (1) from the root surface notch to the apical extent of the junctional epithelium and (2) from the apical extent of the junctional epithelium to the free gingival margin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Anti-tussive activity of benproperine enantiomers on citric-acid-induced cough in conscious guinea-pigs.

The anti-tussive effect of the R-(+)- and S-(-)-enantiomers of benproperine was evaluated and compared with that of the racemate on cough induced by 7.5% citric acid in conscious guinea-pigs. All the three compounds, intraperitoneally administered 1.5 h before the test, significantly inhibited citric-acid-induced cough. The ID50 values (effective doses for 50% inhibition) (with 95% confidence intervals) were 16.1 (9.1-28.4), 23.3 (11.2-48.6), 25.4 (11.7-55.1) mg kg(-1) for the number of coughs in the 3 min of challenge, and 11.9 (5.3-26.6), 13.5 (5.6-32.4), 19.2 (12.8-28.9) mg kg(-1) for the number of coughs in the 5 min immediately after the challenge, for (+/-)-benproperine, R-(+)-benproperine and S-(-)-benproperine, respectively. These findings suggest that the use of either enantiomer does not show any advantage over the racemate with regard to their anti-tussive effect.

Animals↗
PubMed2004

Acetate enhances citric acid production by Yarrowia lipolytica when grown on sunflower oil.

It was discovered that the addition of 10 g/l acetate to a medium containing 30 g/l sunflower oil caused a drastic increase in citric acid production by Yarrowia lipolytica UOFS Y-1701 i.e. from 0.5 g/l in the absence of acetate to 18.7 g/l in the presence of acetate. Similarly, the ratio of citric acid:isocitric acid increased significantly from 1.7:1 in the absence of acetate to 3.7:1 in the presence of acetate after 240 h of growth.

Acetates↗
PubMed1979

Changes in the contents of adenine nucleotides and intermediates of glycolysis and the citric acid cycle in flight muscle of the locust upon flight and their relationship to the control of the cycle.

1. The contents of some intermediates of glycolysis, the citric acid cycle and adenine nucleotides have been measured in the freeze-clamped locust flight muscle at rest and after 10s and 3min flight. The contents of glucose 6-phosphate, pyruvate, alanine and especially fructose bisphosphate and triose phosphates increased markedly upon flight. The content of acetyl-CoA is decreased after 3min flight whereas that of acetylcarnitine is decreased markedly after 10s flight, but returns towards the resting value after 3min flight. The content of citrate is markedly decreased after both 10s and 3min flight, whereas that of isocitrate is changed very little after 10s and is increased by 50% after 3min. The content of oxaloacetate is very low in insect flight muscle and hence it was measured by a sensitive radiochemical assay. The content of oxaloacetate increased about 2-fold after 3min flight. A similar change was observed in the content of malate. The content of ATP decreased about 15%, whereas those of ADP and AMP increased about 2-fold after 3min flight. 2. Calculations based on O(2) uptake of the intact insect indicate that the rate of the citric acid cycle must be increased >100-fold during flight. Consequently, if citrate synthase catalyses a non-equilibrium reaction, the activity of the enzyme must increase >100-fold during flight. However, changes in the concentrations of possible regulators of citrate synthase, oxaloacetate, acetyl-CoA and citrate (which is an allosteric inhibitor), are not sufficient to account for this change in activity. It is concluded that there may be much larger changes in the free concentration of oxaloacetate than are indicated by the changes in the total content of this metabolite or that other unknown factors must play an additional role in the regulation of citrate synthase activity. 3. The increased content of oxaloacetate could be produced via pyruvate carboxylase, which may be stimulated during the early stages of flight by the increased concentration of pyruvate. 4. The decreases in the concentrations of citrate and alpha-oxoglutarate indicate that isocitrate dehydrogenase and oxoglutarate dehydrogenase may be stimulated by factors other than their pathway substrates during the early stages of flight. 5. Calculated mitochondrial and cytosolic NAD(+)/NADH ratios are both increased upon flight. The change in the mitochondrial ratio indicates the importance of the intramitochondrial ATP/ADP concentration ratio in the regulation of the rate of electron transfer in this muscle.

Adenine Nucleotides↗
PubMed1990

The influence of inflammation of the human male genital tract on secretion of the seminal markers alpha-glucosidase, glycerophosphocholine, carnitine, fructose and citric acid.

Biochemical analysis was made of specific accessory gland products in the ejaculates of 362 men suffering from various acute inflammatory diseases of the reproductive tract and 33 normozoospermic patients acting as controls. The ejaculate content of the epididymal markers alpha-glucosidase and L-carnitine, but not glycerophosphocholine, was significantly reduced in ejaculates from men with epididymitis; citric acid was reduced in men suffering from prostatitis; both citric acid and alpha-glucosidase were reduced in men suffering from adnexitis. The ejaculate content of epididymal and prostatic markers in prostato-urethritis (adnexitis), where the exact localization of the inflammation was unclear, was not as low as in epididymitis or prostatitis. Seminal vesicle function, as judged from semen volumes and seminal fructose, was not different in these groups of patients. The results, although strongly related to the clinical diagnosis, were unrelated to the microbiological flora of the semen and indicate that both the epididymis and the prostate glands are involved in some forms of adnexitis.

Adolescent↗
PubMed1997

Use of labeling pattern of liver glutamate to calculate rates of citric acid cycle and gluconeogenesis.

The use of the labeling pattern of hepatic glutamate during infusion of L-[3-13C]- or [3-14C]lactate to calculate rates of citric acid cycle activity and gluconeogenesis has been proposed. We tested the validity of this approach by perfusing isolated rat livers (48 h starved) with pyruvate and lactate (10% enriched with [3-13C]lactate) without (control) or with infusion of glucagon (to inhibit pyruvate kinase), mercaptopicolinate (to inhibit phosphoenolpyruvate carboxykinase), or dichloroacetate (to stimulate pyruvate dehydrogenase). Compared with control experiments, glucagon increased glucose output (P < 0.05) and decreased the calculated flux through pyruvate kinase (P < 0.05). Mercaptopicolinate almost totally suppressed glucose production and dramatically reduced the calculated gluconeogenic rate and flux through phosphoenolpyruvate carboxykinase (P < 0.001). Dichloroacetate moderately increased the calculated flux through pyruvate dehydrogenase (P < 0.05). In experiments with perfused livers from fed rats, the calculated gluconeogenic rate and flux through phosphoenolpyruvate carboxykinase were very low compared with control experiments (P < 0.001), whereas the pyruvate dehydrogenase flux was increased (P < 0.05). Therefore, the expected modifications of the citric acid cycle activity and gluconeogenic rate were clearly detected using the labeling pattern of glutamate to calculate these metabolic rates. Except for the perfusions with mercaptopicolinate, the dilution by isotopic exchange in the oxaloacetate pool calculated from the model agreed with the actual dilution of enrichment between liver pyruvate and phosphoenolpyruvate. The present results support the validity of this approach to trace liver metabolism.

Animals↗
PubMed1984

The effect of citric acid on repair after delayed tooth replantation in dogs.

An experimental study of maxillary incisors in dogs was carried out to test the hypothesis that demineralization of denuded root surfaces by citric acid to expose collagen matrix fibrils might improve the rate of periodontal regeneration after replantation of traumatically avulsed and dried teeth, provided that the root surface is not traumatized during replantation or postoperatively. Experimental teeth (group 4) were allowed to dry in air for 45 min. A mid-portion of the root was then root-planed extensively, treated with citric acid for 3 min, rinsed with saline, and replanted. The apical region and a cervical collar were not instrumented, ensuring precise reseating and stability of the tooth during the postoperative period. Control teeth were either replanted immediately (group 1), bench-dried for 45 min and replanted (group 2), or bench-dried and the entire root surface root-planed and acid-treated before replantation (group 3). Histological examination of block specimens after 21 days of healing showed complete periodontal regeneration in group 1 and, by contrast, a high rate of ankylosis, inflammatory resorption, and surface resorption in group 2. Root planing and acid treatment of bench-dried teeth (group 3) did not improve the healing response, whereas the mid-root region of teeth in group 4 showed an absence of inflammatory resorption and less ankylosis than groups 2 and 3. These preliminary observations indicate that the frequency of adverse healing results after delayed replantation can be reduced by removing nonvital soft tissue remnants, demineralizing the root surface, and preventing mechanical trauma to the root surface in the postoperative period.

Animals↗
PubMed2003

Biofilm bacteria inactivation by citric acid and resuspension evaluations for drinking water production systems.

The study investigates the inactivation of biofilm bacteria colonized on the surface of polyvinyl chloride (PVC) pipes delivering either groundwater or treated wastewater. It does so using a citric acid (C6H8O7) solution. The results of the study showed that the optimal conditions of the biofilm bacteria inactivation were over 10,000 mg/L citric acid concentration and 60 minutes of contact time at least. Under these conditions, the removal efficiency could reach above 99.999% for heterotrophic plate count (HPC) bacteria and 99.95% for coliform bacteria. The study also showed that the biofilm bacteria were the major sources of planktonic bacteria resuspended into water purified by drinking water production systems (DWPS).

Biofilms↗
PubMed1987

Hormonal regulation of fluxes through pyruvate dehydrogenase and the citric acid cycle in mammalian tissues.

Three key dehydrogenases in the mitochondria of higher animals have been found to be activated by Ca2+ ions; these are pyruvate dehydrogenase and two enzymes in the citric acid cycle, NAD-isocitrate dehydrogenase and oxoglutarate dehydrogenase. Activation can also be demonstrated within permeabilized and intact mitochondria. Evidence is summarized that when hormones and other extracellular stimuli increase the cytoplasmic concentration of Ca2+, then this results in an increase in the intramitochondrial concentration of Ca2+. In this way, rates of pyruvate oxidation and citric acid cycle flux are increased, and hence there is an increase in NADH supply for the respiratory chain under conditions where there is an enhanced demand for ATP. In contrast, the activation of pyruvate dehydrogenase which is observed in adipose and other tissues exposed to insulin is brought about by a Ca2+-independent mechanism.

Animals↗
PubMed1985

The pharmacokinetics of chlortetracycline orally administered to turkeys: influence of citric acid and Pasteurella multocida infection.

A physiologically based pharmacokinetic model was developed to describe the absorption and disposition of chlortetracyline (CTC) in the healthy and diseased (fowl cholera) turkey. The CTC was given (with and without citric acid) as an oral (15 mg/kg) or i.v. (1 mg/kg) dose. When minerals (0.3 g/L Ca2+, 0.1 g/L Mg2+) were dissolved in the bird's drinking water, the model indicated that the addition of citric acid (mass ratio of 10 citrate: 1 CTC) increased the fraction of dose absorbed from 0.06 to 0.16; once absorbed, the fractions of drug eliminated by renal excretion, biliary secretion, and chemical decomposition were 50, 46, and 4%, respectively. The presence of fowl cholera appeared to increase plasma levels by increasing the intestinal permeability and lowering the hepatic and/or renal clearance.

Administration, Oral↗
PubMed1989

[Study on new gingival tissue attachment following flap surgery. Gingival attachment to cementum in curettage of the superficial layer following the use of citric acid].

Since endotoxin may be absorbed only in the superficial layer of cementum leaving the deep cementum unchanged morphologically, the cementum of teeth with periodontal involvement was examined. The author considered that the application of citric acid after curetting of only the superficial cementum was better root treatment than complete removal of the cementum. The aim of this study was to examine histological events during the formation of new fibrous attachment to demineralized cementum after flap surgery following citric acid treatment in fifteen dogs. The demineralized cementum prevented the apical proliferation of junctional epithelium. The fibroblasts apposed to the exposed cemental collagen produced numerous new fibrils. Furthermore, the newly-formed collagen fibrils appeared to link with the exposed ones. These findings suggest that this root treatment would facilitate the formation of new fibrous attachment.

Animals↗
PubMed1997

Influence of calcium on fungal growth, hyphal morphology and citric acid production in Aspergillus niger.

Addition of 0.5 g/L CaCl2 to the fermentation medium lowered the final biomass dry mass by 35% and increased the uptake of phosphate and sucrose, and the production of citric acid by 15, 35 and 50%, respectively. In a medium deprived of Ca2+ the microorganism displayed both a pelleted and a filamentous form of growth, the hyphae being scarcely branched, without bulbous cells. An addition of Ca2+ induced a pelleted form of growth, highly branched hyphae and numerous bulbous cells. Bulbous cells growing in the presence of Ca2+ exhibited cell walls composed of laminated layers, and featured vesicles associated with the wall and/or the cell membrane, containing numerous inclusions. The cytotoxic effect of high concentrations of citric acid in the medium as well as an increase of the activity of N-acetyl-beta-D-glucosaminidase, a lytic enzyme, might be involved in these morphological changes.

Aspergillus niger↗
PubMed1984

Connective tissue regeneration to periodontally diseased roots, planed and conditioned with citric acid and implanted into the oral mucosa.

This investigation used autogenous submucosal implants of root sections to study the connective tissue healing to periodontally diseased roots which had previously been planed and demineralized with citric acid. Eighteen implants were performed, with each being removed 2 to 24 weeks after implantation. The results showed new connective tissue attachment to the old cementum and to the dentin. After 18 weeks, in all specimens new cementum had formed on the dentin, with collagen fibers attached to it. No deposition of new cementum on the old cementum was noted. The formation of new cementum on roots placed in an environment without periodontal ligament cells might be ascribed to the inductive principle of demineralized dentin. The results suggest that a diseased root which has been planed and conditioned with citric acid is likely to form a new connective tissue attachment, even if it is placed in an environment without periodontal ligament cells. They also suggest that the factor inhibiting potential new connective tissue attachment is the condition of the root surface, rather than the lack of an adjacent progenitor cell population.

Adult↗