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PubMedDate not supplied

[Acid etching of prefabricated porcelain veneers].

The aim of the present work is to study on standard porcelain teeth the acid concentration to produce the micromechanic retention with the cemented resin and then to enamel. Teeth were beater-up following the described technique, the application of two different types of etch solutions: hydrochloric acid and fluorhidric acid, in a lack of application time between 10 to 20 minutes. With the purpose of determine the type of etch solution that produce the best amount of micropores in standed porcelain laminates veneers we can conclude that: to the internal etched of the standard porcelain laminates veneer, the utilization of fluorhidric acid is the most convenient, also is necessary the previons stand blaster with aluminum oxide of 25 um to increase the retentive capacity over the etch surface.

Acid Etching, Dental↗
PubMed1999

[Histologic comparison of treating root surfaces with different acids].

OBJECTIVE: To study the healing mechanism of different etching agents for periodontitis-affected teeth in animal models. METHODS: The animal models of defect alveolar bone were prepared, and the isolated teeth with periodontitis were scaled according to periodontal surgery in vitro. After different acid acid-treatment, the dentin blocks were implanted into defect bones, then the results were examined histologically after 3, 7, 14, 28 days respectively. RESULTS: There was less inflammatory reaction in tetracycline group after operation. At the later stages, the healing in tetracycline group was characterized by osseointegration without resorption. But hydrochloric acid group and citric acid group showed different reactions. CONCLUSION: Periodontal tissue repair differs with the use of different acids.

Animals↗
PubMed2003

c-Fos immunoreactivity in the brain after esophageal acid stimulation.

The goal of this study was to use c-Fos immunohistochemistry to establish a rat model for studying the central projection of the esophageal afferent neurons during acid exposure. A cannula was placed in the esophagus of anesthetized Wistar rats with the tip approximately 2 cm above the lower esophageal sphincter (LES). Hydrochloric acid (0.1 N HCl, 50 mmol/L) with pepsin (3,200-4,500 U/mL), at pH 1.6, was then perfused into the esophagi of the experimental rats (n = 8) at 10 mL/hr continuously for 50 minutes. Normal saline solution (0.9% NaCl) was used in control rats (n = 6), and home cage control animals (n = 6) were given no stimulation. Thirty minutes after the perfusion, the rat was killed and the brain was removed and processed for c-Fos immunohistochemistry. A transverse section of the esophagus, 2 cm above the LES, was stained with hematoxylin and eosin stain for light microscopy. c-Fos immunoreactivity was significantly increased in a number of brain regions in the rats receiving the acid plus pepsin perfusion. These areas included the central amygdala, the Kölliker-Fuse nucleus, the nucleus of the solitary tract (NTS), the medial part of the NTS, the interstitial part of the NTS, the commissural part of the NTS, the paratrigeminal nucleus, the ambiguus nucleus, and the rostroventrolateral recticular nucleus. Perfusion with acid-pepsin solution also resulted in morphologic changes in the esophagus on light microscopy. This study suggests that acid plus pepsin perfusion of esophagus results in both neural activation in areas of the central nervous system and damage to the esophagus in an animal model.

Animals↗
PubMed2004

[Benzo[c][2,7]naphthyridines from 2,6-dinor-nifedipine and its dimethyl 2,5-dicarboxylate isomer].

The reaction of 2-nitrobenzaldehyde with methyl propiolate and ammonium acetate in acetic acid yields 2,6-dinor-nifedipine (1a) and the isomeric rac. 1,4-dihydropyridine (DHP) 1b. The DHP 1 are dehydrogenated both chemically and by anodic oxidation using a rotating platinum electrode (RPE) by means of differential pulse voltammetry (DPV) affording the corresponding pyridines 2a, b. Compound 1a is more stable, while compound 1b is less stable than nifedipine. Irradiation of the DHP 1 with UV-A light forms the nitrosophenyl-pyridines 3, which cyclize after addition of conc. hydrochloric acid to yield the chloro substituted hydroxamic acids 4a, b. The hydroxamic acids 4c, d are obtained treating 2a, b with zinc in acetate buffer pH 4.6. The hydroxamic acids 4b, d demonstrate only a moderate inhibition of 5-lipoxygenase (5-LOX) of human whole blood compared with the activity of the reference compound zileutone. The formation of 15-HETE is also inhibited. Compound 4a reduces the activity of cyclooxygenase. The lactames 5, obtained from the hydroxamic acids 4 by desoxygenation with phosphorus trichloride, react with phosphoryl chloride to give compounds 6, representing educts for potential agents against malaria.

Antimalarials↗
PubMed1976

Comparison of three methods for grouping streptococci.

Two new methods for serological grouping of beta-hemolytic streptococci, the nitrous acid extraction procedure of El Kholy et al. and the slide agglutination method of Christensen et al., were compared with the Lancefield hot-hydrochloric acid extraction method in classifying 92 strains of groups A, B, C, and G. The nitrous acid extraction method was easily performed, specific, and sensitive when highly potent antisera were used. For the Christensen method these highly potent antisera had to be diluted to avoid cross-reactions between groups A and C and groups B and G, respectively. A few strains, most of them group B, could not be grouped by the latter method. Using these three grouping methods, two sets of commercial sera were compared with the more potent sera supplied by R. C. Lancefield. The low antibody content of these commercial sera, especially anti-group B and G sera, contributed to the inferior results obtained in some of the grouping reactions.

Agglutination Tests↗
PubMed1994

Increased expression of c-met messenger RNA following acute gastric injury in rats.

The aim of the present study was to evaluate messenger RNA expression of c-met, a hepatocyte growth factor receptor gene, after gastric mucosal injury in rats. Male Sprague-Dawley rats were fasted for 24 hours, received 0.6 N hydrochloric acid (HCl), and served for polyadenylated RNA extraction from the oxyntic gastric mucosa. The transcripts of rat c-met gene were analyzed by reverse-transcript polymerase chain reaction and Northern blotting. Although it was detected even before the HCl administration, the c-met expression increased 6, 24 and 48 hours after the HCl administration. Thereafter, gastric mucosal injury diminished and the c-met expression declined. Hepatocyte growth factor reportedly plays an important role in gastric cell proliferation. The increased c-met expression indicates that this gene may participate in the healing process of gastric mucosa after injury.

Amino Acid Sequence↗
PubMed1990

Biological monitoring of isocyanates and related amines. I. Determination of 1,6-hexamethylene diamine (HDA) in hydrolysed human urine after oral administration of HDA.

1,6-Hexamethylene diamine (HDA), used as raw material in industrial manufacturing operations, was orally administered to six healthy volunteers. After acid hydrolysis of the urine by hydrochloric acid, HDA and the metabolite 6-aminohexanoic acid were quantified. HDA was determined as an ethyl-chloroformate derivative by capillary gas chromatography using thermionic specific detection (TSD), and 6-aminohexanoic acid was quantified by ion chromatography using the ninhydrin reaction. In nonhydrolysed urine, monoacetylated HDA (N-acetyl-1,6-hexamethylene diamine) and HDA, were verified as heptafluorobutyric anhydride derivatives by gas chromatography-mass spectrometry (GC-MS), in a chemical ionization mode using isobutane and ammonia as reagent gases. In hydrolysed urine, a mean of 0.28 mg (range 1-6%) of the administered dose (8.2 mg) was recovered as HDA, and a mean of 0.8 mg (range less than 1-27%) as 6-aminohexanoic acid. The urinary excretion of both the determined compounds was rapid, and the principal part (greater than 90%) of the elimination was completed within 10 h. There was a considerable inter-individual variation in the excreted amounts, but the intra-individual variation in the excretion of HDA was limited. The subjects N-acetylator phenotype was determined by a dapsone test. Three slow acetylators excreted lower amounts (mean 2% of given dose) of HDA than three rapid ones (mean 5%).

Acetylation↗
PubMed1984

A new technique for formation of 99mTc-labelled blood leucocytes and platelets.

99mTc -platelets and 99mTc -leucocytes have been formed at neutral pH in presence of gentistic acid using 99mTc pretreated with concentrated hydrochloric acid and vacuum evaporation. High radiochemical purities and specific radioactivities were obtained. The complexes between 99mTc and the blood cells were found remarkably stable, and further studies for nuclear medicine applications are recommended.

Blood Platelets↗
PubMed1984

Branched-chain alpha-keto acid analysis in biological fluids: preparative clean-up by anion-exchange and analysis by capillary gas chromatography.

A method is given for the quantitative analysis of the alpha-keto derivatives of the branched-chain amino acids in physiological fluids. A sample containing alpha-ketovalerate and alpha-ketocaproate as internal standards is passed through a weak anion-exchange resin at neutral pH. After washing the resin with distilled water, the alpha-keto acids are eluted with 4 M hydrochloric acid--ethanol (50:50). Quinoxalinol derivatives are prepared directly in the eluent, extracted with methylene chloride, and trimethylsilylated. Separation of the derivatives is by capillary gas chromatography on a 30 m fused-silica SE-30 column. Chromatographic separation is superior to that reported for packed column methods, thereby permitting the use of alpha-ketovalerate and alpha-ketocaproate as internal standards.

Animals↗
PubMed2005

Synthesis and study of the cancer cell growth inhibitory properties of alpha-, gamma-tocopheryl and gamma-tocotrienyl 2-phenylselenyl succinates.

Vitamin E succinate selenium-conjugated molecules were synthesized and their apoptogenic properties were evaluated. 4-Methyl-2-phenylselenyl succinate (4) was prepared by the reaction of sodium benzeneselenolate with 2-bromosuccinic anhydrite in methanol solution. The methyl ester was converted to the acid (5) by hydrolysis with aqueous hydrochloric acid. Reaction of the 2-phenylselenyl succinic anhydrite (6) with alpha-tocopherol (1a), gamma-tocopherol (1c), and gamma-tocotrienol (2c) in acidic conditions gave the respective esters. The free radical scavenging properties of alpha-tocopheryl-2-phenylselenyl succinate (7), gamma-tocopheryl-2-phenylselenyl succinate (8), and gamma-tocotrienyl-2-phenylselenyl succinate (9) were evaluated in comparison with those of alpha-tocopheryl succinate (10), gamma-tocopheryl succinate (11), and gamma-tocotrienyl succinate (12), respectively, and the free tocopherols and gamma-tocotrienol. Compounds 7-9 induced a statistically significant decrease in prostate cancer cell viability compared to 10-12, respectively, or 5, exhibiting features of apoptotic cell death and associated with caspase-3 activation. These data show that structural modifications of vitamin E components by 5 enhance their apoptogenic properties in cancer cells.

Apoptosis↗
PubMed2005

Adsorption equilibrium of phenol onto chemically modified activated carbon F400.

In this work the adsorption of phenol solutions onto activated carbon Calgon F400 has been studied. The carbon was modified by acid treatment, using soxhlet extraction with hydrochloric acid 2N for 120 cycles. The treatment did not affect significantly the surface area of the activated carbon but affected significatively the different functional groups, and thus its adsorption properties. Tóth model reproduced satisfactorily the experimental isotherm data and an adsorption enthalpy of -17.9 kJ mol-1 was found, which indicates that the process is exothermic. The pH affected significatively to the adsorption process and an empirical polynomial equation was able to reproduce maximum capacity as a function of pH. The isotherms obtained at pH 3 and 7 are very similar and showed a higher adsorption capacity compared with that obtained at pH 13. The use of phosphate buffer solutions decreased the maximum phenol adsorption capacity, due to the competitive adsorption between the phenol and phosphates. Finally, it was demonstrated that the acid treatment introduced chloride ions into the carbon, giving it properties of ion exchanger.

Adsorption↗
PubMed1985

Measurement of neutral sugars in glycoproteins as dansyl derivatives by automated high-performance liquid chromatography.

Automated high-performance liquid chromatography was used to analyse dansylhydrazine derivatives of neutral sugars in unfractionated acid hydrolysates of four well-characterized glycoproteins: fetuin, ovalbumin, alpha-1-acid glycoprotein and bovine submaxillary mucin. After a simple single-step derivatization at 65 degrees C the sugar derivatives in protein hydrolysates chromatographed as single peaks on reversed-phase C18 columns. The isocratic solvent consisted of 20% (v/v) aqueous acetonitrile containing 0.01 M formic acid, 0.04 M acetic acid and 0.001 M triethylamine. The triethylamine significantly increases the sugar peak height at 254 nm. Repeated automatic sample injection without deterioration of column performance or interference from dansyl hydrazine is not possible with published methods, but was achieved by cleaning the column between each analysis with a solvent of 20% (v/v) acetonitrile and 80% (v/v) methanol. Hydrolysis with 2 M trifluoroacetic acid is superior to 2 M hydrochloric acid for both sugar recovery and convenience but must continue for 6-8 h at 105 degrees C to ensure complete sugar release. We confirmed that mannose is present in most preparations of human high-molecular-weight salivary glycoproteins, and also examined purified bovine skin proteodermatan sulphate. p-Nitrophenylhydrazine derivatives of neutral sugars are readily produced, but do not chromatograph as successfully as the dansyl derivatives while phenylhydrazine derivatives are not easily produced at 65 degrees C. Further development of the method should be possible by producing other hydrazine derivatives of neutral sugars.

Autoanalysis↗
PubMed2004

Measurement and analysis of the relationship between ammonia, acid gases, and fine particles in eastern North Carolina.

An annular denuder system, which consisted of a cyclone separator; two diffusion denuders coated with sodium carbonate and citric acid, respectively; and a filter pack consisting of Teflon and nylon filters in series, was used to measure acid gases, ammonia (NH3), and fine particles in the atmosphere from April 1998 to March 1999 in eastern North Carolina (i.e., an NH3-rich environment). The sodium carbonate denuders yielded average acid gas concentrations of 0.23 microg/m3 hydrochloric acid (standard deviation [SD] +/- 0.2 microg/m3); 1.14 microg/m3 nitric acid (SD +/- 0.81 microg/m3), and 1.61 microg/m3 sulfuric acid (SD +/- 1.58 microg/m3). The citric acid denuders yielded an average concentration of 17.89 microg/m3 NH3 (SD +/- 15.03 microg/m3). The filters yielded average fine aerosol concentrations of 1.64 microg/m3 ammonium (NH4+; SD +/- 1.26 microg/m3); 0.26 microg/m3 chloride (SD +/- 0.69 microg/m3), 1.92 microg/m3 nitrate (SD +/- 1.09 microg/m3), and 3.18 microg/m3 sulfate (SO4(2-); SD +/- 3.12 microg/m3). From seasonal variation, the measured particulates (NH4+, SO4(2-), and nitrate) showed larger peak concentrations during summer, suggesting that the gas-to-particle conversion was efficient during summer. The aerosol fraction in this study area indicated the domination of ammonium sulfate particles because of the local abundance of NH3, and the long-range transport of SO4(2-) based on back trajectory analysis. Relative humidity effects on gas-to-particle conversion processes were analyzed by particulate NH4+ concentration originally formed from the neutralization processes with the secondary pollutants in the atmosphere.

Acids↗
PubMed1992

Effect of acidified enteral feedings on gastric colonization in the critically ill patient.

OBJECTIVE: To evaluate the effect of acidified enteral nutritional formulas (feedings) on gastric colonization and pH in critically ill patients. DESIGN: Randomized, double-blind trial of three groups: a) regular feedings into the stomach; b) regular feedings into the duodenum; and c) acidified feedings into the stomach. Nasogastric aspirates for gastric pH and microbiological determinations were obtained daily for a mean of 5 days after feeding began. SETTING: ICU at a tertiary care hospital. PATIENTS: Thirty-one patients indicated to receive enteral feedings before day 4 in the ICU were randomized. Seven patients had their feedings discontinued because of intolerance, accidental extubation, or tolerance of oral supplementation. One patient received the wrong feedings and was dropped from the study. A total of 23 patients finished the study. They were mostly trauma (n = 15) or neurosurgical (n = 6) patients. The average age was 40 yrs (range 15 to 71). INTERVENTIONS: An enteral formula with a pH of 6.5 was used as the control feeding. Hydrochloric acid was added to the control feeding to titrate the pH to 3.5 and this acidified enteral formula was given to the experimental group. All patients received continuous enteral feedings via an 8-Fr feeding tube. MAIN RESULTS: Seven of eight patients receiving the acidified feedings were sterile (no microbial growth) on receiving feedings compared with five of 15 of those patients receiving regular feedings (p = .027). For those patients initially colonized, four of four patients receiving acidified feedings immediately became sterile and remained so. Only two of ten patients receiving regular feedings remained sterile (p = .021). The mean gastric pH of the acidified group was 3.2 compared with the group receiving regular feedings into the stomach (pH = 4.7) and the group receiving regular feedings into the duodenum (pH = 3.8) (p < .01). There was no evidence of gastrointestinal bleeding in any patient. CONCLUSIONS: Acidified enteral feedings are effective in eliminating and preventing gastric colonization in critically ill patients. Further investigation is needed to assess its effect on nosocomial infection rates.

Acidosis, Lactic↗
PubMed1995

Acid aspiration-induced lung injury in rabbits is mediated by interleukin-8-dependent mechanisms.

Acid aspiration lung injury may be mediated primarily by neutrophils recruited to the lung by acid-induced cytokines. We hypothesized that a major acid-induced cytokine was IL-8 and that a neutralizing anti-rabbit-IL-8 monoclonal antibody (ARIL8.2) would attenuate acid-induced lung injury in rabbits. Hydrochloric acid (pH = 1.5 in 1/3 normal saline) or 1/3 normal saline (4 ml/kg) was instilled into the lungs of ventilated, anesthetized rabbits. The rabbits were studied for 6 or 24 h. In acid-instilled rabbits without the anti-IL-8 monoclonal antibody, severe lung injury developed in the first 6 h; in the long-term experiments, all rabbits died with lung injury between 12 and 14 h. In acid-instilled rabbits given the anti-IL-8 monoclonal antibody (2 mg/kg, intravenously) either as pretreatment (5 min before the acid) or as treatment (1 h after the acid), acid-induced abnormalities in oxygenation and extravascular lung water were prevented and extravascular protein accumulation was reduced by 70%; in the long-term experiments, anti-IL-8 treatment similarly protected lung function throughout the 24-h period. The anti-IL-8 monoclonal antibody also significantly reduced air space neutrophil counts and IL-8 concentrations. This study establishes IL-8 as a critical cytokine for the development of acid-induced lung injury. Neutralization of IL-8 may provide the first useful therapy for this clinically important form of acute lung injury.

Animals↗
PubMedDate not supplied

Enteral glutamine spares endogenous glutamine in chronic acidosis.

Metabolic acidosis associated with the catabolic state mobilizes muscle nitrogen and releases it into blood as glutamine (GLN) targeted for renal consumption and base generation. Because GLN removed by the kidneys during acidosis is a major drain on the GLN available to other sites, subsequent deprivation may lead to impaired organ function. Conversely, GLN supplementation may spare endogenous supplies and restore organ function. To test this, Sprague-Dawley rats weighing between 250 and 350 g were pair-fed elemental diets supplemented with GLN 4.9 g/L (GLN-ED) or an equivalent mixture of neutral amino acids substituted for GLN (ED). Acid loading was effected by adding hydrochloric acid to the liquid diet (110 mmol/L). Animals were studied in metabolic cages for five consecutive 24-hour urine collection periods and then anesthetized for short-term studies of interorgan fluxes and tissue GLN content. Acidosis effected an increase in ammonium nitrogen excretion (fivefold) and a reciprocal decrease (24%) in urea nitrogen excretion. Enteral GLN had no effect on the acidosis-effected ammonium (2170 +/- 71 vs 2059 +/- 361 mumol/100 g, ED vs GLN-ED, respectively) or urea excretion (5522 +/- 95 vs 5915 +/- 984 mumol/100 g, ED vs GLN-ED, respectively). Although arterial blood GLN was not increased in the GLN-ED group (531 +/- 58 vs 438 +/- 51 nmol/mL, p = .10), both liver and muscle GLN were elevated (11,650 +/- 1137 nmol/g vs 7063 +/- 578 and 5503 +/- 489 and 4742 +/- 333 nmol/g, respectively, each p < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed2003

William Prout: early 19th century physician-chemist.

In the early 19th century, the discoveries of new substances in the healthy and diseased body spawned a search for chemical explanations for physiologic phenomena to guide medical diagnosis and control therapy. William Prout's work on the nature and treatment of diseases of the urinary organs established his reputation as one of Britain's most distinguished physiological chemists. Prout was very skeptical of chemical remedies because of possible side effects, but he suggested iodine treatment for goiter. He emphasized that a satisfactory diet should include carbohydrates, fats, protein, and water. In 1824, he showed that the acid of the gastric juice was hydrochloric acid. Prout applied chemical methods and reasoning to physiology and was criticized for his view that the body's vital functions could be explained by chemistry. His remedy for lack of progress in animal chemistry was for physiologists to become chemists. Prout stimulated much discussion on atomic theory by his hypothesis that the atomic weights of all chemical elements are whole-number multiples of the atomic weight of hydrogen and that the chemical elements were condensed from hydrogen atoms.

Chemistry, Clinical↗
PubMed1992

Localization of hepatitis C virus RNA in human liver biopsies by in situ hybridization using thymine-thymine dimerized oligo DNA probes: improved method.

To establish the most proper method of in situ hybridization in detection of HCV-RNA in the liver, various detailed procedures were examined using frozen as well as paraffin-embedded sections of tissue derived from patients. In frozen sections of the liver from hepatitis C patients obtained at autopsy or surgery, HCV-RNA was detectable by in situ hybridization using thymine-thymine dimerized oligonucleotide DNA probes when the sections were treated with ethanol-acetic acid at first, then 0.2 N hydrochloric acid, proteinase K (0.02 u/ml) and DNase. When the paraffin-embedded liver sections were used, more intense proteinase K treatment (0.2-2 u/ml) was required to expose viral RNA and even after that, the positive HCV-RNA signals were less than those in frozen sections, because the cytoplasmic RNA in the routine paraffin-embedded sections was preserved unevenly and less than in frozen sections. These findings indicate that in situ hybridization of HCV-RNA is useful for diagnosing HCV infection and should be a potent tool for monitoring the state of virus activities during therapy. However, the liver biopsy method should be modified so that RNA is retained properly to utilize biopsies more effectively for the routine diagnosis of HCV infection.

Base Sequence↗