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PubMed1996

Acceptance of minerals and other compounds by calcium-deprived rats: 24-h tests.

We measured 24-h spontaneous intake of four to eight concentrations of 31 different solutions by groups of rats fed control or low-calcium diets. Relative to controls, those fed low-calcium diet had increased acceptance of one or more concentrations of sodium chloride, sodium acetate, and sodium bicarbonate, but not sodium gluconate. Differences in palatability between these sodium salts were unimportant because the rats fed low-calcium diet consumed more sodium chloride even if this was made less acceptable by adulteration with citric acid. The possibility that calcium-deprived rats have an enhanced general cation or mineral appetite was supported by findings of increased acceptance of one or more concentrations of nine of ten chloride minerals tested (aluminum chloride, ammonium chloride, ferric chloride, ferrous chloride, magnesium chloride, sodium chloride, potassium chloride, strontium chloride, zinc chloride). However, there were no differences in acceptance of any concentration of cesium chloride, magnesium sulfate, or lead acetate. Moreover, calcium-deprived rats drank more hydrochloric acid and malic acid than did controls. Thus the effect of calcium deficiency on intake was not confined to minerals. Acidity or bitterness did not appear important because there was no difference between the groups in intake of sulfuric acid, citric acid, or quinine hydrochloride. Consistent with the exacerbating effects of phosphates on calcium deprivation, deprived rats had decreased intakes of phosphates (sodium phosphate, potassium phosphate). However, they also had decreased intakes of sucrose and saccharin. It is clear that calcium deprivation does not induce a general increase in acceptance of all taste solutions, but there appears to be no simple explanation for what these animals consume.

Acids↗
PubMed1993

Antimicrobial and antioxidant activities of unripe papaya.

The meat, seed and pulp of Carica papaya Linn., a popular traditional medicinal herb grown in the tropics, was shown by the agar-cup method to be bacteriostatic against several enteropathogens such as Bacillus subtilis, Enterobacter cloacae, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The same parts of papaya were unequivocably demonstrated by electron spin resonance spectrometry to scavenge 1,1-diphenyl-2-picrylhydrazyl (5.8 x 10(14) spins/ml), hydroxyl (5.1 x 10(14) spins/ml) and superoxide (1.2 x 10(14) spins/ml) radicals with the seed giving the highest activity at concentrations (IC50) of 2.1, 10.0 and 8.7 mg/ml, respectively. The superoxide dismutase (SOD)-like activity in the meat, seed and pulp amounts to about 32, 98 and 33 units/ml; comparable to those of soybean paste miso, rice bran and baker's yeast. Vitamin C, malic acid, citric acid and glucose are some of the possible antioxidative components in papaya. Our study correlates the bacteriostatic activity of papaya with its scavenging action on superoxide and hydroxyl radicals which could be part of the cellular metabolism of such enteropathogens. This is indicative of the pathophysiological role of these reactive oxygen species in gastrointestinal diseases and papaya's ability to counteract the oxidative stress.

Anti-Bacterial Agents↗
PubMed1991

Bicarbonate-catalyzed hydrolysis of hexamethylene diisocyanate to 1,6-diaminohexane.

The hydrolysis of hexamethylene diisocyanate (HDI) in water was tested in a dynamic and stationary system. Without catalysts, the reaction was very slow (less than 1% in 10 min at 30 degrees C) while the addition of simple carboxylic-acid-containing neutral buffers markedly catalyses the formation of 1,6-diaminohexane as the known hydrolysis product. The catalytic efficiency of formic acid, oxalic acid, acetic acid, lactic acid, citric acid and carbonic acid increased in this order while phosphate, glycine and glutamate were inactive even at very high concentrations. A 20 mM bicarbonate buffer was the optimal catalyst, but below this concentration the rate of HDI hydrolysis was drastically reduced. It is suggested that the hydrolysis of inhaled HDI in the lungs may be catalysed by bicarbonate in the blood, giving rise to amines found as urinary metabolites following occupational exposure.

Bicarbonates↗
PubMed2001

The applied physiology of cough.

The cough reflex is such an important defense mechanism of the respiratory tract that a thorough knowledge of its applied physiology in respiratory disease is essential for clinicians. It is a well-integrated reflex, which has afferent limb consisting of receptors and afferent nerves, the central cough center in the brainstem and the efferent limb consisting of motor nerves supplying the muscles of coughing. The cough process consists of inspiratory phase, compressive phase and expiratory phase. Stimuli that can initiate the cough process can be central or peripheral in the lungs or outside the lungs. The important function of the cough reflex is to maintain the airways and alveoli clear and healthy. The mechanisms by which it achieves this are (i) high velocity of expiratory gas flows produced in the expiratory phase (ii) the compression of the lungs and airways by high positive pleural pressure generated in the compressive phase. Cough threshold can be determined by giving acetic acid, citric acid or capsaicin inhalation challenge test. This has practical application in clinical research. The pathophysiological basis of different types of cough encountered in clinical practice is discussed.

Acetic Acid↗
PubMed2002

[Microbial biomass affected by cadmium with the occurrence of organic acids in red soil].

Soil microbial biomass carbon and nitrogen were determined after adding fixed concentration of organic acids and changeable concentration of cadmium in pre-incubated red soil and 14-day incubation at 25 degrees C. The results show that soil microbial biomass carbon and nitrogen in the soil added with organic acids decreased with increasing concentration of cadmium. When the concentration of cadmium was higher than 25 mg.kg-1, the microbial biomass carbon and nitrogen in the soil added with low molecular weight of organic acids (oxalic acid, acetic acid, citric acid, tartaric acid) were lower than those without the addition of organic acids, indicating that low molecular weight of organic acids could increase the toxicity of cadmium. On the contrary, the microbial biomass carbon and nitrogen in the soil added with low molecular weight of organic acids were higher than those without the addition of organic acids when the concentration of cadmium was lower than 25 mg.kg-1, indicating that low molecular weight organic acids could decrease the toxicity of cadmium. The microbial biomass carbon and mitrogen in the soil containing humic acid were higher than those without the addition of organic acids, indicating that humic acid could decrease the toxicity of cadmium. However, the C:N ratio of soil microbial biomass was increased with increasing concentration of cadmium. Organic acids could increase microbial biomass carbon and nitrogen when soil was not added with cadmium.

Acetic Acid↗
PubMed2003

Effects of different acid and sodium hypochlorite treatments on dentin collagen: a FEISEM analysis.

PURPOSE: To evaluate if different acid treatments of dentin surface might remove different amount of mineralized dentin, thus exposing and modifying the CF network. METHODS: Dentin disks prepared from human third molars with a low-speed diamond saw were etched for 15 seconds with the tested acids: citric acid 10%, maleic acid 10%, 2.5% oxalic acid, 35% phosphoric acid and 24% EDTA gel. Specimens were then submitted to a 5% solution of NaOCl for 2 minutes or 5 minutes, fixed, and observed utilizing a field emission in lens SEM (FEISEM). Control specimens were also prepared by omitting the etching agent and/or the NaOCl solution. RESULTS: The different acid treatments created specific dentin morphological pattern. CF exposure was in relationship with the acid used. The NaOCl solution greatly affects the acid etched dentin by removing the CF, nevertheless the effect of NaOCl was greatly influenced by the previous acid treatment.

Acid Etching, Dental↗
PubMed1995

A quantitative model for prediction of iron bioavailability from Indian meals: an experimental study.

The major goal of the study was to explore the possibility of developing an updated model that integrates the effect of various enhancers and inhibitors for predicting the potential availability of iron from typical Indian vegetarian meals. The interaction effects of four constituents namely ascorbic acid, citric acid, tannic acid and calcium phosphate was studied using a standard cereal meal (STD meal) providing 3 mg non-heme iron/250 ml homogenate. Based on the data, a regression equation was evolved which was tested for its predictive power as applied to a set of 10 typical Indian meals. Regression analysis of the data revealed that both ascorbate and citrate emerged as equally strong enhancers while tannate and calcium phosphate demonstrated strong inhibitory effect on iron availability in the STD meal. Further, when the prediction equation, generated on the basis of the interaction effect data was applied to the typical Indian meals, it showed a high correlation coefficient (r = 0.76) between the analysed values for iron availability vs the values computed using the enhancer and inhibitor contents of the meals. Comparison with the only other model available in the literature namely that of Monsen & Balintfy (1982) revealed that the present model was far better in predicting iron availability from cereal based Indian meals (r = 0.76) than Monsen's model (r = 0.19). The findings of the present study substantiated the hypothesis that a regression model, evolved from a cereal meal, by integrating the effect of enhancers as well as inhibitors, rather than only enhancers, provides a more precise estimate of iron availability from typical Indian meals. A limitation of the model however, was that phytate could not be incorporated into the equation.

Ascorbic Acid↗
PubMedDate not supplied

An in vitro shear bond strength study of enamel/dentin bonding systems on enamel.

The purpose of this study was to compare the enamel shear bond strengths achieved with four acid conditioners employed by current enamel/dentin bonding systems (maleic acid, citric acid, nitric acid, oxalic acid) with a 37% phosphoric acid etching technique. The study also compared enamel shear bond strengths between the manufacturers' enamel/dentin conditioner used with an unfilled enamel bonding resin. The facial surfaces of 135 bovine incisors were ground flat and divided into nine test groups of n=15. Conditioning and bonding procedures were carried out following manufacturers' instructions. The phosphoric acid groups were etched for 15 seconds, rinsed for 30 seconds, and dried for 20 seconds with compressed air. All bonding was accomplished at a constant temperature of 21 degrees C and a relative humidity of 60%. A single composite restorative resin (Z-100) was used with all specimens to eliminate variables between composite materials. All specimens were thermocycled 2500 times (5 to 45 degrees C) and had a total storage time of 21 days prior to shear testing on an Instron at a crosshead speed of 1.0 mm/minute. Shear strengths were calculated by dividing load at failure by specimen area. A light microscope was used to determine failure mode. The data were subjected to Bartlett's test for homogeneity of variance and were found not to be homogeneous. The Welch Test was applied and indicated that the treatments used had influence on bond strength at P<0.05. There was no significant difference in bond strength values between traditional phosphoric acid/enamel bonding resin and Mirage Bond Dentin and Enamel Adhesive, Clearfil Liner Bond System, and Scotchbond Multi-Purpose Dental Adhesive System.

Acid Etching, Dental↗
PubMed2004

Change of monochloroacetic acid to biodegradable organic acids by hydrothermal reaction.

The feasibility of biodegradability improvement induced from the structural conversion of refractory pollutants by hydrothermal reaction was investigated. Monochloroacetic acid (MCAA) was selected as a preliminary material represented for linear hydrocarbon structured refractory pollutants. Under the tested conditions, MCAA was partially destructed and then converted to biodegradable reaction products by hydrolysis, dehydration and thermal decomposition. The identified products were glycolic acid, citric acid and formic acid. Total organic carbon (TOC) reduction during the structural conversion did not exceed 24%, except the results at the reaction conditions of 350 degrees C and 17 MPa. However, Produced biodegradable organic acids were reduced by thermal decomposition with increasing reaction temperature and time. At the reaction temperature of 250 and 300 degrees C, biodegradability (BOD/COD(Cr)) was reached at 0.51 in 6.9 min and 0.52 in 7.4 min despite the presence of dissociated chlorine ions. The detachment of recalcitrant chlorine ion from MCAA and the production of biodegradable organic acids by hydrothermal reaction were directly related to the biodegradability improvement of reaction products.

Acetates↗
PubMed1989

Influence of in vitro lactic acidosis on central nervous system neurons.

Central nervous system (CNS) cultured neurons while exposed to different concentrations and pH of L-lactic acid exhibited in general chromatin clumping, vacuolization in the cytoplasm, appearance of lipid bodies, accumulation of polyribosomes, cytoplasmic lucency and swollen and aggregation of mitochondria. These alterations progressed with lower pH and longer exposure to lactic acid. At pH 7.4, there was no considerable pathologic changes in cultured neurons irrespective to concentrations of lactic acid added. Comparable results were obtained with the use of other weak acid (citric acid) indicating that the observed changes were due to acidic pH rather than lactate per se.

Acidosis, Lactic↗
PubMed2000

Speciation of insulin-mimetic VO(IV)-containing drugs in blood serum.

The biospeciations of three potential insulin-mimetic VO(IV) compounds, VO(maltolate)2, VO(picolinate)2 and VO(6-Me-picolinate)2, in blood serum were assessed via modelling calculations, using the stability constants reported in the literature for the binary insulin-mimetic complexes and their ternary complexes formed with the most important low molecular mass binders in the serum: oxalic acid, lactic acid, citric acid and phosphate. The binding capabilities of two high molecular mass serum proteins, albumin and transferrin, were also taken into account.

Citric Acid↗
PubMed1988

Effects of dried whey and copper sulfate on the growth responses to organic acid in diets for weanling pigs.

Five 21-d to 28-d experiments involving 484 pigs weaned at 28 +/- 2 d of age were conducted to evaluate the effects of addition of organic acid to a fortified, corn-soybean meal diet (CS) or to a similar diet containing 15% dried whey (CSW) on performance of pigs. The effects of an antibiotic-sulfonamide combination (110 mg chlortetracycline, 110 mg sulfamethazine, 55 mg penicillin/kg) and the interactive effects of Cu sulfate (250 ppm Cu) and acid also were evaluated. The acid was a commercial product consisting of 96% organic acid (citric acid and Na citrate, 2:1). Treatments in Exp. 1 and 2 were factorial arrangements of the CS or CSW basal diets supplemented with 0 or 1% (Exp. 1) and 0, .5 or 1% (Exp. 2) of the acid product. Pigs fed diets containing whey consumed more feed (P less than .01) and gained weight faster (P less than .05), but they had feed/gain responses similar to those of pigs fed the CS diet. Addition of 1% acid improved (P less than .01) growth rate of pigs fed the CS diet but did not improve (P greater than .25) growth rate of pigs fed the CSW diet. Feed/gain was improved (P less than .01) by acid addition to both the CS and the CSW diets. Improvements in gain and feed/gain were similar for the two levels of acid. In Exp. 3 and 4, factorial combinations of 0 and 1% acid and 0 and 250 ppm Cu were evaluated in diets containing an antibiotic-sulfonamide combination. In addition, a negative control diet (no antibiotics, acid or Cu) was included. Pigs fed diets containing antibiotics gained faster and more efficiently (P less than .01) than those fed the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

[Simultaneous determination of 11 organic acids in fruit juice by ion exclusion chromatography].

A method for the quantitative determination of 11 organic acids (oxalic acid, citric acid, tartaric acid, malic acid, ascorbic acid, lactic acid, succinic acid, formic acid, acetic acid, glutaric acid and fumaric acid) in fruit juice was developed successfully. It was based on an ion exclusion chromatographic separation under the conditions of isocratic elution with 17 mmol/L sulphuric acid solution with the ICE-ION-300 ion exclusion column, and the UV detection at 210 nm. The precision of the method was investigated and the relative standard deviations were from 1.5% to 9.8% (n = 10).

Beverages↗
PubMed1987

[Changes in organic acids in plasma and cerebrospinal fluid in cerebral infarct].

Seventeen patients with recent cerebral infarction were included in the study. The general condition of the patients was evaluated within 3 days after the incidence (rating 1) and 7-9 days after the incidence (rating 2) using a clinical rating scale for internal, psychiatric and neurological findings. The statistical evaluation showed a clinical improvement of the score of 32%. The extent of the brain lesions was determined by cranial computed tomography. Routine analysis of the cerebrospinal fluid included determination of protein, cell count, cell type, glucose, lactic acid, and hemoglobin. In addition, spinal fluid and serum concentration of pyruvic acid, citric acid, fumaric acid, alpha-ketoglutaric acid and alpha-keto-beta-methylvaleric acid (3-MKV) were determined at the two rating times. CSF and serum values of fumaric acid, 3-MKV and pyruvic acid correlated at rating 1, while at rating 2 a correlation existed only for fumaric acid. A trend analysis infarction - postinfarction period showed the concentration of all metabolites to decrease significantly. This is interpreted as a reconstitution of the initially disturbed blood brain barrier function.

Aged↗
PubMed1990

[Interaction between polyethylene films and brombexine HCl in solid dosage form. II. Effects of moisture property on the sorption of the drug].

The interaction between bromhexine HCl and polyethylene containers was studied in solutions and in tablet packaging systems. Various bromhexine HCl aqueous solutions of different pHs were stored in polyethylene containers at 25 degrees C. The remaining amount of bromhexine HCl was determined by high performance liquid chromatography. It was observed that the transition of bromhexine HCl to polyethylene was inhibited by the addition of some surfactants into the solution, and by lowering the solution pH. In the solid dosage forms, influences of the additives were also studied. It was observed that the decrease of the content of bromhexine HCl in the solid dosage form was inhibited by the addition of acids (citric acid, tartaric acid) and surfactant (sodium dodecyl sulfate) and accelerated by the addition of sodium bicarbonate, similarly to those in solutions. The results indicated that the transition to polyethylene films was influenced by the molecular state of bromhexine HCl.

Adsorption↗
PubMed2003

Effect of MTAD on the bond strength to enamel and dentin.

The purpose of this study was to compare the effect of MTAD (a mixture of a tetracycline isomer [doxycycline], an acid [citric acid], and a detergent [Tween 80]) and phosphoric acid on the bond strength to enamel and dentin using a conventional OptiBond Solo Plus dentin adhesive system. One hundred flat surfaces (50 enamel/50 dentin) were prepared for bonding. Specimens were embedded in acrylic with the flat surface exposed. One of the following surface treatments was applied before bonding composite with Optibond Solo Plus (Kerr Corp): 1 min NaOCl/1 min EDTA; 1 min NaOCl/1 min MTAD; 30 s etch with H3PO4 (positive control), 2 min saline (negative control), or 20 min NaOCl/5 min MTAD (clinical protocol for MTAD). Shear bond strength was tested 30 min after bonding. Data were analyzed using a one-way ANOVA followed by the Student-Newman-Keuls multiple comparison method. Surface pretreatment with acid etch resulted in the greatest enamel bond strengths (p < 0.05). All surface pretreatments were superior to saline for dentinal bonding (p < 0.05). On the basis of our findings, it appears that teeth endodontically treated with the MTAD protocol for clinical use (20 min 1.3% NaOCl/5 min MTAD) may not need any additional dentin conditioning before the application of the dental adhesive.

Analysis of Variance↗
PubMed1991

Potential radiopharmaceuticals labeled with titanium-45.

The potential of some compounds labeled with cyclotron-produced titanium-45 (45Ti) as radiopharmaceuticals was studied. Properties of colloid formation of 45TiOCl2 or 45TiO-phytate in vivo resulted in the highest radioactivity uptake in the rat liver, followed by the spleen, suggesting potential for imaging the reticuloendothelial system. Three 45TiO-complexes with diethylenetriaminepentaacetic acid, citric acid and human serum albumin showed the highest radioactivity levels in the blood over 6 h. The binding of the 45Ti with plasma transferrin in vitro and in vivo suggested that these compounds can be used for estimating the blood volume. Also, potential as an indicator representing the breakdown of the blood-brain barrier in the rat was demonstrated by autoradiography.

Animals↗
PubMed1997

Treatment of intrabony defects by polylactic acid matrix barrier--a one-year follow-up study.

The present investigation was conducted to evaluate the effect of a polylactic acid-citric acid softened membrane barrier during guided tissue regeneration (GTR) surgery on human intrabony defects. Eighteen patients were treated in the study and 16 patients completed the 1-year follow-up. In all, 27 intrabony defects were treated and clinical soft tissue measurements, including probing depth (PD), probing attachment level (PAL), and recession, were recorded. Results of the investigation demonstrated a significant reduction in PD (3.7 mm), a significant gain in PAL (4.2 mm), and a slight increase in recession (1.2 mm).

Adult↗