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Results for “CITRIC ACID”

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PubMed1986

Dietary citric acid enhances absorption of aluminum in antacids.

Ten healthy men ingested, twice daily between meals, during each of the seven-day experimental periods: (a) citric acid (as lemon juice), (b) Al(OH)3, or (c) Al(OH)3 + citric acid. Whole blood sampled after each dietary period was analyzed electrothermally after digestion with nitric acid. Moderate, but significant, increases in mean Al concentrations as compared with pretreatment values [5 (SD 3) micrograms of Al per liter] were seen after ingestion of either citric acid or Al(OH)3: 9 (SD 4) and 12 (SD 3) micrograms/L, respectively. Ingestion of both Al(OH)3 and citric acid resulted in a more pronounced, highly significant (p less than 0.001) increase in Al concentrations, to 23 (SD 2) micrograms Al/L, probably owing to formation and absorption of Al-citrate complexes.

Adult↗

PubMed1973

Intergenic complementation of glucoamylase and citric acid production in two species of Aspergillus.

All auxotrophs of Aspergillus foetidus and all but two auxotrophs of A. niger which we isolated yield glucoamylase and citric acid, respectively, at levels below that of the prototrophic strain from which they were derived. Results of representative heterokaryon tests suggest that the nucleus was principally responsible for the inheritance of citric acid or glucoamylase production. Most somatic diploid strains of A. foetidus gave rise to higher yields of glucoamylase when compared to their haploid component strains. Both heterokaryons and somatic diploid strains of A. niger synthesized between auxotrophs which were simultaneously reduced in citric acid yields also gave rise to enhanced yields when compared with their haploid components. The yields of a heterokaryon and somatic diploid synthesized between two high producers of citric acid were not higher than those of respective haploid components. We concluded from these results that gene dosage (or ploidy) does not increase the yield of citric acid. The apparent enhancement in yields observed in diploids or heterokaryons synthesized between auxotrophs with reduced yields in both species can be interpreted as resulting from intergenic complementation.

Amino Acids↗

PubMed2000

Citric acid demineralization and subepithelial connective tissue grafts.

BACKGROUND: The present study was designed to evaluate the effect, if any, of citric acid root demineralization in the outcome of subepithelial connective tissue grafts performed to cover localized gingival recessions. METHODS: Thirty-six patients participated, each providing one gingival recession; 19 received citric acid demineralization, while 17 did not. All were treated surgically with subepithelial connective tissue grafts and followed for 6 months. At baseline and 6 months, the following parameters were recorded: plaque index, gingival index, recession height, probing depth, recession width, and amount of keratinized tissue. Data were analyzed statistically to 1) evaluate the results achieved with each procedure individually over time and 2) compare the results obtained with the 2 procedures after 6 months. RESULTS: Results showed significant reductions in recession height after 6 months independently of whether citric acid was applied or not (2.79+/-0.79 versus 2.56+/-0.73). Similarly, recession width was significantly reduced (3.74+/-1.19 versus 3.50 +/-0.73), and the width of keratinized tissue was significantly increased (2.47+/-1.6 versus 2.3+/-1.2). No significant changes in probing depth were found (-0.16+/-0.06 versus -0.13+/-0.81). No significant differences were found when both techniques were compared in any one of the parameters analyzed (all P >0.30). CONCLUSIONS: It is concluded that: 1) the subepithelial connective tissue graft procedure provides a satisfactory solution in the treatment of localized gingival recessions, and 2) citric acid demineralization does not affect the clinical outcome of the surgical technique.

Adolescent↗

PubMed1991

A morphological comparison of radicular dentin following root planing and treatment with citric acid or tetracycline HCl.

The conditioning of root surfaces with saturated solutions of citric acid or tetracycline is unpredictable in facilitating new attachment, perhaps due to the low pH of these solutions which may be denaturing the organic matrix of the root as well as demineralizing the surface. The purpose of the present study was to compare the effects of a saturated solution of citric acid (pH = 1) with that of a 0.5% solution of tetracycline HCl (pH = 3.2) on radicular dentin with regard to the removal of the smear layer, exposure of dentinal tubule openings, and demineralization of the peritubular dentin. 10 bovine incisors were used in this study. The crowns and apical 1/3 of the root were resected and the resulting root segments were then frozen in icy freon. The cementum was fractured off of the root to produce a fracture-exposed, non-instrumented dentin surface. This fracture-exposed dentin surface was divided into 4 specimens, the 1st being a fracture-exposed, non-instrumented dentin control specimen (FE). After removal of the (FE) specimen from the root segment, the remainder of the fracture-exposed dentin surface was thoroughly root planed and then subdivided into the 3 remaining specimens. One of these specimens served as the root planed dentin surface (RP); another specimen (CA) was immersed in saturated citric acid (pH = 1) for 5 min and then washed in water for 5 min; the final specimen (T) was immersed in a 0.5 mg/ml solution of tetracycline HCl for 5 min and rinsed in water for 5 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2003

Decalcifying effect of EDTA-T, 10% citric acid, and 17% EDTA on root canal dentin.

OBJECTIVE: An in vitro study was conducted to determine the efficacy of 17% EDTA plus 1.25% sodium lauryl ether sulfate (EDTA-T), 10% citric acid, and 17% EDTA with respect to Ca(++) extraction. STUDY DESIGN: The root canals of 90 extracted human canines were instrumented by using the step-back technique. The teeth were randomly divided into 9 groups of 10 teeth each according to the solution and time intervals involved (ie, 3, 10, and 15 minutes). The Ca(++) concentration of the solution was determined by using atomic absorption spectroscopy. RESULTS: At 3 minutes, there was no significant difference between Ca(++) extraction by 10% citric acid and 17% EDTA (P >.05). EDTA-T had the least efficacy for Ca(++) extraction (P <.05). At 10 minutes and 15 minutes, there were no significant differences between 10% citric acid and 17% EDTA or between EDTA-T and 17% EDTA (P >.05). However, 10% citric acid was significantly better than EDTA-T in terms of Ca(++) extraction (P <.05). CONCLUSION: Both 10% citric acid and 17% EDTA are good decalcifying agents when the step-back technique is used.

Chelating Agents↗

PubMed1980

Influence of micronutrients on citric acid production by Candida lipolytica (Y 1095).

FeSO4 . 7 H2O, PbSO4, CuSO4 . 5 H2O, MnSO4 . 4 H2O, ZnSO4 . 7 H2O, CoCl2 . 6 H2O, and (NH4)6Mo7O24 . 4 H2O were added to the fermentation medium to investigate their potentialities on citric acid production by Candida lipolytica (Y 1095). FeSO4 . 7 H2O and MnSO4 . 4 H2O were more suitable than the other micronutrients for citric acid production. Addition of certain amino acids to the fermentation medium completely inhibited biosynthesis of citric acid by Candida lipolytica (Y 1095). When the fermentation medium was supplied with certain vitamins, yield of citric acid was increased in the presence of thiamine, nicotinic acid, and nicotinamide. The optimum concentration of thiamine which favoured yield of citric acid was 6 mg/l.

Amino Acids↗

PubMed1998

The effects of microbial phytase, citric acid, and their interaction in a corn-soybean meal-based diet for weanling pigs.

Crossbred weanling pigs (an equal number of barrows and gilts) with an average initial weight of 7.4 (Exp. 1) or 9.6 kg (Exp. 2) were used in two 4-wk experiments (Exp. 1, n = 96; Exp. 2, n = 96) to investigate the effects of added phytase or citric acid on performance, rib mineralization, gastric pH, and digestibility measurements. A corn-soybean meal-based diet low in Ca and P was used in both experiments. In Exp. 1, three citric acid levels (0, 1.5, or 3.0%) and four phytase levels (0, 250, 500, or 750 U/kg) were used in a 3 x 4 factorial arrangement of treatments. In Exp. 2, two citric acid levels (0 or 2.0%) and three phytase levels (0, 250, or 500 U/kg) were used in a 2 x 3 factorial arrangement of treatments. Phosphorus was maintained at .33 and .34% in Exp. 1 and 2, respectively. Calcium was maintained at a 2.5:1 ratio with total available P (available P plus the estimated released phytate P by phytase) in Exp. 1 and at a level of .44% in Exp. 2. In both experiments, BW and feed consumption were measured weekly, and pen fecal samples were collected twice daily for 5 d during wk 4. At the end of wk 4, the barrow in each pen was killed following a fast-refeed-fast (22-1-2 h) regimen for collection of 10th ribs and stomach digesta. In Exp. 1 and 2, phytase addition did not affect (P > .05) performance but linearly increased (P < .05) rib shear force, shear energy, dry bone weight, ash weight, ash percentage, and Ca and P digestibilities. Addition of citric acid in both experiments reduced dietary pH and stomach digesta pH (P < .05). The addition of citric acid improved (P < .05) ADG, feed efficiency, and Ca digestibility in Exp. 1, but it had no effect on performance and Ca digestibility in Exp. 2. In summary, the additions of citric acid and phytase to weanling pig diets were each beneficial, but no synergistic effects were observed.

6-Phytase↗

PubMed1986

The effect of citric acid on growth of proteolytic strains of Clostridium botulinum.

In strictly anaerobic conditions in a culture medium adjusted to pH 5.2 with HCl and incubated at 30 degrees C, inocula containing less than 10 vegetative bacteria of Clostridium botulinum ZK3 (type A) multiplied to give greater than 10(8) bacteria per ml in 3 d. Growth from an inoculum of between 10 and 100 spores occurred after a delay of 10-20 weeks. Citric acid concentrations of 10-50 mmol/l at pH 5.2 inhibited growth from both vegetative bacteria and spore inocula, a concentration of 50 mmol/l increasing the number of vegetative bacteria or of spores required to produce growth by a factor of approximately 10(6). The citric acid also reduced the concentration of free Ca2+ in the medium. The inhibitory effect of citric acid on vegetative bacteria at pH 5.2 could be prevented by the addition of Ca2+ or Mg2+ and greatly reduced by Fe2+ and Mn2+. The addition of Ca2+, but not of the remaining divalent metal ions, restored the concentration of free Ca2+ in the medium to that in the citrate-free medium. The inhibitory effect of citric acid on growth from a spore inoculum was only partially prevented by Ca2+. Citric acid (50 mmol/l) did not inhibit growth of strain ZK3 at pH 6 despite the greater chelating activity of citrate at pH 6 than at pH 5.2. The effect of citric acid and Ca2+ at pH 5.2 on vegetative bacteria of strains VL1 (type A) and 2346 and B6 (proteolytic type B) was similar to that on strain ZK3.

Calcium↗

PubMed2005

Demineralization effect of EDTA, EGTA, CDTA and citric acid on root dentin: a comparative study.

The purpose of this study was to biochemically compare the decalcifying effects of 1% EDTA (pH 7.4), 1% EGTA (pH 7.4), 1% CDTA (pH 7.4), 1% citric acid solutions (pH 1.0 and 7.4) and saline solution (control) on root dentin. Forty-eight single-rooted teeth were used in this study. The canals were instrumented by the step-back technique and the roots were randomly divided into six equal experimental groups (n = 8) according to the irrigating agent tested. A total of 30 microL of each solution was pipetted into the root canal and allowed to set undisturbed for 5 minutes. After this time, 15 microL of the solutions were removed from each canal using a Hamilton syringe and placed in a container with 5 mL of deionised water. The microg/mL concentration of calcium ion (Ca2+) extracted from the root canal samples was determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by means of the Kruskal-Wallis and Mood's median tests. Citric acid solution at pH 1.0 removed more calcium than at pH 7.4 and than the other chelating solutions tested (p < 0.05). No differences were observed between EDTA and EGTA. Both EDTA and EGTA removed significantly more calcium than CDTA and citric acid at pH 7.4 (p < 0.05). There were no differences between citric acid at pH 7.4 and saline solution, which had the least efficacy for Ca2+ extraction (p > 0.05). These results indicate that citric acid at pH 1.0 is a good alternative as an irrigating solution to remove the smear layer and facilitate the biomechanical procedures.

Chelating Agents↗

PubMed2004

Enhancement of citric acid production with ram horn hydrolysate by Aspergillus niger.

The potential use of ram horn hydrolysate (RHH) as a supplement for improvement of citric acid production by Aspergillus niger NRRL 330 was studied. For this purpose, first RHH was produced. Ram horns were hydrolyzed by treating with acid (6 N-H2SO4) and the RHH was obtained. With the addition of RHH to the fermentation medium with a final concentration of 4% (optimal concentration), citric acid value reached a maximum value (94 g/l), which is 52% higher than that of the control experiment. The addition of 4% (v/v) RHH enhanced citric acid accumulation, reduced residual sugar concentration and stimulated mycelial growth. Adding 4% RHH had no adverse effects on A. niger. As a result, RHH was found to be suitable as a valuable supplement for citric acid production in the submerged fermentation.

Animals↗

PubMed1998

Functional citric acid cycle in an arcA mutant of Escherichia coli during growth with nitrate under anoxic conditions.

The operation of the citric acid cycle of Escherichia coli during nitrate respiration (anoxic conditions) was studied by measuring end products and enzyme activities. Excretion of products other than CO2, such as acetate or ethanol, was taken as an indication for a non-functional cycle. From glycerol, approximately 0.3 mol acetate was produced; the residual portion was completely oxidized, indicating the presence of a partially active citric acid cycle. In an arcA mutant devoid of the transcriptional regulator ArcA, glycerol was completely oxidized with nitrate as an electron acceptor, demonstrating derepression and function of the complete pathway. Glucose, on the other hand, was excreted mostly as acetate by the wild-type and by the arcA mutant. During growth on glucose, but not on glycerol, activities of succinate dehydrogenase and of 2-oxoglutarate dehydrogenase were missing nearly completely. Thus, the previously described strong repression of the citric acid cycle during nitrate respiration occurs only during growth on glucose and is the effect of anaerobic and, more important, of glucose repression. In Pseudomonas fluorescens (but not Pseudomonas stutzeri), a similar decrease of citric acid cycle function during anaerobic growth with nitrate was found, indicating a broad distribution of this regulatory principle.

Anaerobiosis↗

PubMed1999

Determination of the oxygen-18/oxygen-16 isotope ratios of sugar, citric acid and water from single strength orange juice.

The ratio of the stable isotopes of oxygen (18O/16O) has been measured in the sugar, citric acid and water from authentic single strength orange juices, originating from a number of different countries. The sugars and citric acid were recovered from the juices and their 18O/16O ratios were determined by pyrolysis/continuous flow-isotope ratio mass spectrometry (Py/CF-IRMS). The 18O/16O ratio of the fruit juice water was determined by the carbon dioxide/water equilibration method. The delta 18O/1000 values of 45 different sugars ranged from +29.1 to +38.8/1000 and 15 citric acids ranged from +18.9 to +25.4/1000. The delta 18O/1000 value of the water present in the same samples ranged from -2.1 to +7.8/1000. A correlation was evident between the delta 18O/1000 values of the sugar, citric acid and water from the juices. This information can be used to improve the assessment of the authenticity of commercial 'freshly squeezed' orange juices. The detection of the presence of reconstituted orange juice concentrate in 'freshly squeezed' orange juices was improved by 37% using regression analysis of the combined water and sugar delta 18O/1000 ratios when compared to the use of delta 18O/1000 ratios of fruit juice water alone.

Beverages↗

PubMed1978

[Comparative studies on the quantity of fructose and citric acid in the sperm from bulls at different seasons of the year].

The contents of fructose and citric acid in the semen of seven bulls of different ages were examined over a one-year period. The bulls were used as sires in the Artificial Insemination Station. The semen production was within the normal range. In the course of the investigations the temperature and moisture regimes of the air in the barns was optimal for the semen production of the bulls. No statistically significant changes in the amount of fructose and citric acid were established at different average diurnal temperatures and the relative moisture content in the different annual seasons. A marked positive correlation (r = 0.070 +/- 0.04) was observed between the changes in the contents of fructose and citric acid throughout the year. These changes were in an inverse correlation with the number of spermatozoa per mL of semen (r = 0.26 +/- 0.08) and in a moderate one for the citric acid (r = 0.49 +/- 0.06). In the bulls of the Red Dannish cattle there was a statistically significant decrease in the number of spermatozoa and a statistically significant increase in the number of immobile spermatozoa in the winter season.

Animals↗

PubMed2002

Quinine and citric acid elicit distinctive Fos-like immunoreactivity in the rat nucleus of the solitary tract.

The present experiment investigated Fos-like immunoreactivity (FLI) in the nucleus of the solitary tract (NST) after intraoral infusions of 0.1 M citric acid, 0.3 M NaCl, and 0.3-30 mM quinine monohydrochloride (QHCl) in awake, behaving rats. Increases in QHCl concentration produced increases in the numbers of FLI-labeled neurons in the rostral part of the intermediate (i(r)) and rostral (r) NST, but the topographic distribution of FLI was consistent across QHCl concentrations and distinctive compared with effects of citric acid. Quinine elicited FLI concentrated in the medial third of the nucleus; acid elicited more broadly distributed FLI concentrated farther laterally. Surprisingly, in contrast to QHCl and citric acid, NaCl produced FLI that was indistinguishable from that produced by water. Although the functional significance of these patterns is unknown, citric acid and QHCl are nonpreferred stimuli but produced different oromotor behaviors. QHCl (30 mM) elicited approximately 3.2 times as many gapes as citric acid (0.1 M), and acid elicited more ingestive responses. Parallel differences in FLI expression suggest that different NST regions may have distinctive roles in triggering oromotor behaviors.

Administration, Oral↗

PubMed2002

Endothelin-1 in citric acid aerosol inhalation-induced airway constriction of guinea pigs.

Endotheline-1 (ET-1) has been shown to enhance tachykinin-induced airway constriction. This study was designed to test whether ET-1 is involved in citric acid-induced bronchoconstriction. Forty-eight anesthetized-paralyzed guinea pigs were divided into six groups of 8 animals each: saline control; citric acid; ET-1; ET-1 + citric acid; BQ123 + ET-1 + citric acid; and BQ788 + ET-1 + citric acid. BQ123 and BQ788 are specific ETA and ETB receptor antagonists, respectively. Each animal in the saline control group received 50 breaths of 4 ml saline aerosol and in all citric acid-treated groups was given 50 breaths of 4 ml aerosol generated from 0.6 M citric acid. In all ET-1-treated groups, each animal was exposed to aerosol generated from 10(-8) M ET-1. The animal in the ET-1 + citric acid group was exposed to ET-1 5 min prior to the citric acid. For the last two groups, each animal was first exposed to aerosol generated from either 10(-5) M BQ123 or 10(-5) M BQ788. Five min later, the animal was exposed to ET-1; and then 5 min later was followed by citric acid. Dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 sec (FEV(0.1)), and maximal expiratory flow at 30% total lung capacity (Vmax 30) were obtained before and 3-15 min after citric acid. Either citric acid or ET-1 inhalation caused significant decreases in Crs, FEV(0.1), and Vmax 30, indicating airway constriction. Citric acid-induced airway constriction, for most cases, was not significantly augmented by ET-1. However, either BQ123 or BQ 788 significantly attenuated the airway constriction induced by the combination of ET-1 and citric acid. Also, in an additional study, either BQ123 or BQ788 significantly attenuated citric acid-induced airway constriction. These data suggest that endogenous ET-1 plays an important role in citric acid aerosol-induced airway constriction in guinea pigs.

Administration, Inhalation↗

PubMed1987

Effects of sodium citrate, potassium citrate, and citric acid in preventing experimental calcium oxalate urolithiasis in rats.

Male Wistar-strain rats which had been fed a glycolic-acid diet developed severe nephrocalcinosis with urinary calculi within 4 weeks. Rats fed the same diet with citrate salts added had, however, either slight or no nephrocalcinosis without any stones in the urinary system. Nephrocalcinosis intermediate between those in the citrate groups and the glycolic-acid group, with some urinary calculi, was observed in the citric-acid group. During the experiment, the urinary oxalate concentration increased markedly and was higher in the citrate and citric-acid than in the glycolic-acid group. The urinary citrate concentration was significantly higher in the citrate groups and lower in the citric acid and glycolic-acid groups. Therefore, citrate salts can be concluded to inhibit nephrocalcinosis and calculi formation as a result of decreased urinary saturation by means of increase in urinary citrate, in spite of a slight increase in the urinary oxalate.

Animals↗

PubMed1996

Interaction of citric acid with hydroxyapatite: surface exchange of ions and precipitation of calcium citrate.

The use of citric acid is efficacious and distinctive in the demineralization of dentinal root surfaces for periodontal regeneration and in the etching and conditioning of enamel or dentin for bonding restorative resins. To decipher the role of citric acid in these applications, it is important that one have a basic understanding of its interaction with synthetic hydroxyapatite. The uptake or removal of citrate ions from aqueous solutions of citric acid (4 to 100 mmol/L, 10 mL) by hydroxyapatite (1 g) was studied at 22 degrees C after a given reaction period (from 3 hr to 11 days) by immediate spectrophotometric monitoring of the concentrations of the filtrates (214 nm). The concentrations of calcium, phosphate, and hydrogen ions were also determined in the same solutions. The interaction: (i) is a time-independent ionic-exchange process with the substrate when the initial acid concentrations are dilute (4 to 12.5 mmol/L), and (ii) is a reactive process that is time-dependent for higher acid concentrations. The exchange process shows an adsorption of about one citrate ion per (100) face of the unit cell of hydroxyapatite for a maximally exchanged surface. The curves representing the reactive process may be quantitatively or qualitatively explained on the basis of the supersaturation of the solutions with respect to calcium citrate and its slow precipitation. The physico-chemical analysis of the needle-shaped birefringent crystals of the precipitate from the supersaturated solutions confirms the precipitate to be Ca3(citrate)2.4H2O.

Acid Etching, Dental↗

PubMed2006

Effect of the sodium hypochlorite and citric acid association on smear layer removal of primary molars.

This study aimed to assess the capacity of a sodium hypochlorite and citric acid (CA) association (the latter at different concentrations) in removing coronal smear layer (SL) of primary teeth. For this purpose, the pulp chamber roof and floor of 28 primary molars were removed to obtain enamel and dentine disks. SL was produced on the internal walls of the disks using high-speed drills. The disks were irrigated with 1% sodium hypochlorite and citric acid at different concentrations (CA-4%, CA-6%, CA-8% and CA-10%), and with 0.9% sodium chloride. The samples were split and observed under SEM. Scores were attributed to the obtained photomicrographs, according to the amount of SL present. It was noted that all the tested concentrations of citric acid used after the sodium hypochlorite were capable of removing SL. The results were analyzed by the Kruskal-Wallis test, and there was no significant statistical difference among the scores of the groups tested. However, it was observed that CA-8% and CA-10% caused peritubular dentine destruction, and that CA-4% presented a larger number of samples with dense SL. Based on these results, 6.0% citric acid in association with 1% sodium hypochlorite is suggested as auxiliary chemical substances for primary teeth irrigation.

Chelating Agents↗