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At least 1,495 records · Page 83Linked to original sources
PubMed2005

Enamel opacities removal using two different acids: an in vivo comparison.

Computerized analysis assessed quantitatively the efficacy of microabrasion using 37% phosphoric and 18% hydrochloric acids with pumice on removal of enamel opacities. Baseline and after one month photos were taken and analyzed by Paint Shop Pro 7 software and Image Pro Express 4.0. Nonparametric tests were used. Results depicted significant differences immediately versus one month post treatment for both acids. It was concluded that both acids can be used, and as time passes enamel color improvement occurs.

Adolescent↗
PubMed2005

Low positive end-expiratory pressure does not exacerbate nebulized-acid lung injury in dogs.

It is not clear if low end-expiratory pressures contribute to ventilator-induced lung injury in large animals. We sought to determine whether ventilation with a low level of positive end-expiratory pressure (PEEP) worsens preexisting permeability lung injury in dogs. Lung injury was initiated in 20 mongrel dogs by ventilating with nebulized 3N hydrochloric acid until a lower inflection point (LIP) appeared on the respiratory system pressure-volume loop. One group of 10 dogs was then ventilated for 4 hours with PEEP set below the LIP (low PEEP), whereas the remaining group of dogs was ventilated for the same time period with similar tidal volumes but with PEEP set above the LIP (high PEEP). We found histologic evidence of reduced alveolar volumes in the low-PEEP animals. However, there were no differences in neutrophil infiltration, lung lobe weights, pulmonary capillary hemorrhage or congestion, or arterial endothelin-1 concentration between the 2 protocol groups. In conclusion, we were unable to demonstrate that ventilation with PEEP set below the LIP exacerbates hydrochloric acid-induced lung injury in dogs.

Animals↗
PubMed1982

Differential effect of acid meals on abomasal emptying and secretion in the milk-fed calf.

Preruminant (milk-fed) calves were prepared with an abomasal and re-entrant duodenal cannulae to assess the effect of acid test meals on abomasal emptying and secretion. Isotonic saline meals acidified with hydrochloric acid to pH 2 instilled directly into the abomasum did not affect abomasal emptying or acid and pepsin secretion when compared with saline meals at pH 6. Isotonic saline meals at pH 1.2 significantly inhibited abomasal acid secretion, but had little effect on emptying or pepsinogen secretion. Abomasal emptying, acid secretion and pepsinogen secretion were significantly inhibited when acid was introduced into the duodenum, irrespective of the acidity of the test meal. It is concluded that in the calf acid meals inhibit gastric acid secretion alone without effect on pepsinogen secretion and abomasal emptying. All three abomasal functions, however, were inhibited by acidification of the duodenum.

Abomasum↗
PubMed1989

Reaction of gallium arsenide with concentrated acids: formation of arsine.

Crystalline particles of gallium arsenide (GaAs) (approximately 2 microns in diameter) react with concentrated hydrochloric acid (HCl) (11.6 to 9 M) to form highly toxic arsine (AsH3) gas. None of the other strong acids that were investigated reacted with gallium arsenide to form AsH3. A spectrophotometric method, based on the reaction of AsH3 with silver diethyldithiocarbamate in a chloroform solution containing morpholine, was used to detect AsH3 gas dissolved in aqueous solutions and to determine the AsH3 gas that was liberated by the reaction of GaAs with HCl. Active sites on the gallium arsenide surface initiate the reaction that forms AsH3 gas. Absorption of oxygen or ions from solution on these active sites inhibits the formation of AsH3.

Arsenic↗
PubMed1976

Experimental acid-aspiration pneumonia in the rabbit. A pathologic and morphometric study.

Four anesthetized rabbits given intratracheal injections of hydrochloric acid, pH 1.5, 2 ml/kg, were killed 4 h later. A fifth rabbit was an untreated control. Each lung had a few red-brown patches of compression atelectasis. Microscopically, treated lungs had a severe exudative necrotizing bronchitis, bronchiolitis, and alveolitis. There was also intra-alveolar hemorrhage and edema. Electron microscopy showed folds, projections and focal swellings of type I cells lining affected alveoli. A morphometric study showed 69% of parenchyma to be normal, 26% edematous and 5% hemorrhagic. In the airways 58% of the epithelium was damaged.

Animals↗
PubMed1985

Corneal responses to acid measured in vivo.

With the use of a micropolarographic system, the effects of a series of unbuffered hydrochloric acid concentrations on oxygen uptake by the corneal epithelium of rabbit were measured in vivo. Based on an exposure model of 60 s, followed by a saline rinse, concentrations of 0.50 N and less were found to produce initial flux variations, which did, however, return to near normal levels within 20 min. But a concentration of 0.75 N for that duration was found to produce an abrupt and sustained decrease in oxygen uptake. This time-strength combination was noted to be substantially greater than that required to produce a similar effect with alkali. A concentration of 1.0 N HCI produced responses indistinguishable from a cornea denuded of its epithelium.

Animals↗
PubMed1982

Salivary secretion in reflux esophagitis.

It has been speculated that impaired salivary flow and contents contribute to abnormal acid clearance in patients with reflux esophagitis. To test this hypothesis, salivary secretion of volume, bicarbonate, and N-acetylneuraminic acid was measured in patients with reflux esophagitis, in age- and sex-matched controls, and in healthy young volunteers. Resting saliva was collected by permitting the saliva to drip into a flask every 30 s. Parotid saliva was collected by means of a Lashley capsule during stimulation by oral infusion of 1 ml/min of 2% citric acid. Total mixed saliva was collected by a dental sucker during esophageal perfusion with water and 10-mM hydrochloric acid. The volume of resting saliva and its concentration of bicarbonate were similar in the three groups. The concentration and the output of N-acetylneuraminic acid were higher in the young volunteers than in the two other groups. The volume flow and the composition of stimulated parotid saliva were similar in the three groups of subjects. Volume of total mixed saliva and concentration of bicarbonate and N-acetylneuraminic acid during esophageal perfusion with water were higher in patients with reflux esophagitis than in age- and sex-matched controls and were similar to the values found in young healthy volunteers. Acid perfusion increased the secreted volume of total mixed saliva by 150% and the concentration of bicarbonate by 30% in healthy young volunteers, but not in patients with reflux esophagitis and in the healthy age- and sex-matched controls; the concentration of N-acetylneuraminic acid was left unaffected by acid perfusion in all three groups. These findings disprove the hypothesis of impaired salivation in reflux esophagitis. The age-related loss of salivary response to acidic esophageal perfusion might be the reason why reflux esophagitis with peptic lesions affects predominantly elder people.

Adult↗
PubMed1987

Repair of rabbit duodenal mucosa after acid injury in vivo and in vitro.

Epithelial repair after luminal acid exposure was studied in the rabbit duodenum in vivo and in vitro. Hydrochloric acid (200 mM, 30 min in vivo; 10 mM, 10 min in vitro) caused a uniform damage of the mucosa confined to the villi. After demarcation and detachment of the necrotic tissue the defect was bridged by the remaining viable epithelial cells, resulting in a reduction of villus height. This process of mucosal repair proceeded continuously, so that 9 h after acid damage only 33% of villi in the proximal duodenum and 41% in the distal duodenum remained not fully restored, at both luminal pH 7 and luminal pH 3. The difference is due to the higher acid susceptibility of the distal duodenum. In vitro, most of the mucosal surface was reconstituted 5 h after acid injury, at both luminal pH 7.4 and luminal pH 3. The potential difference declined and reversed after mucosal damage; restitution to original values was only observed at luminal pH 7 in vivo and luminal pH 7.4 in vitro.

Animals↗
PubMed1984

Effect of esophageal emptying and saliva on clearance of acid from the esophagus.

We studied clearance of acid from the esophagus and esophageal emptying in normal subjects. A 15-ml bolus of 0.1 N hydrochloric acid (pH 1.2) radiolabeled with [99mTc]sulfur colloid was injected into the esophagus, and the subject swallowed every 30 seconds. Concurrent manometry and radionuclide imaging showed nearly complete emptying of acid from the esophagus by an immediate secondary peristaltic sequence, although esophageal pH did not rise until the first swallow 30 seconds later. Esophageal pH then returned to normal by a series of step increases, each associated with a swallow-induced peristaltic sequence. Saliva stimulation by an oral lozenge shortened the time required for acid clearance, whereas aspiration of saliva from the mouth abolished acid clearance. Saliva stimulation or aspiration did not affect the virtually complete emptying of acid volume by the initial peristaltic sequence. We conclude that esophageal acid clearance normally occurs as a two-step process: (1) Virtually all acid volume is emptied from the esophagus by one or two peristaltic sequences, leaving a minimal residual amount that sustains a low pH, and (2) residual acid is neutralized by swallowed saliva.

Acids↗
PubMed2002

Coordinated regulation of gastric chloride secretion with both acid and alkali secretion.

Gastric secretion of hydrochloric acid requires protons and chloride, yet the mechanisms and regulation of gastric chloride secretion remain unclear. We developed an in vivo technique to simultaneously measure acid/base and chloride secretion into the gastric lumen of anesthetized rats. The cannulated stomach lumen was perfused with weakly pH-buffered chloride-free solution containing a chloride-sensitive fluorophore [5 microM N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide (MQAE)]. Gastric acid and chloride secretion was detected in gastric effluents by 1) flow-through pH electrode and 2) MQAE fluorescence. Gastric effluent was also collected at 1-min intervals for independent determination of chloride amount by chloridometer. In all conditions, both optical and chemical determinations of chloride report similar amounts of secreted chloride. During luminal perfusion with pH 5 solution, net acid and chloride secretion into the lumen was observed. Pentagastrin stimulated both secretions. In contrast, proton pump inhibition (omeprazole) caused alkalinization of the gastric effluent, but chloride secretion was not diminished. During luminal pH 3 perfusion, net alkali secretion was observed, and chloride secretion at luminal pH 3 was greater than pH 5. When tissue is pretreated with omeprazole at luminal pH 3, the addition of prostaglandin E2 synchronously stimulates both alkali and chloride secretion. Results suggest that both acid and alkali secretions are separately coupled with chloride secretion.

Alkalies↗
PubMed1985

High-pressure acid injection: case report with recommended initial management and therapy.

This report represents a case of high-pressure hydrochloric acid injection of the shoulder girdle, with the resultant need for aggressive debridement in the form of extended forequarter amputation. The accelerated destructive activity of such reducing agents and the need for neutralization or removal of these agents is emphasized. Debridement, copious saline irrigation, and careful periodic monitoring are recommended.

Adult↗
PubMed1977

[Acid application on dental tartar as preliminary treatment before mechanical scaling].

The action of the preparation studied, containing 20% hydrochloric acid in an alcohol-chloroform medium: 1) affected both white tartar as well as the submucosal tartar, progressively replacing the phosphorus radicles of tricalcium phosphate by CL ions, transforming the insoluble tricalcium phosphate into soluble calcium chloride; 2) was practically complete in 2 minutes; 3) was more rapid on tartar than on enamel or even cement; 4) did not appear to alter the superficial structure of the tooth in 4 minutes whilst, for the same period of time, the superficial structure of the cement was deeply attacked with 50% preparations of citric acid or phosphoric acid; 5) in our trials, carried out after 4 minutes treatment, caused the tartar to undergo a relatively superficial but adequate chemical action to facilitate its removel, whilst leaving the underlying hard tissue, enamel or cement, unharmed. It would thus appear that such a substance may be used for the preparation and speeding of mechanical descaling.

Calcium Phosphates↗
PubMed1977

UV spectrophotometric determination of aminophylline, amobarbital, and ephedrine hydrochloride in an antiasthma capsule preparation.

A simple and rapid procedure for the determination of aminophylline, amobarbital, and ephedrine hydrochloride in a capsule preparation is described. Aminophylline and amobarbital are determined simultaneously using differential UV spectrophotometry; ephedrine hydrochloride is determined separately after elution from an alginic acid column with 0.1 N hydrochloric acid.

Aminophylline↗
PubMed1987

Histochemical procedures for the simultaneous visualization of neutral sugars and either sialic acid and its side chain O-acyl variants or O-sulphate ester. I. Methods based upon the selective periodate oxidation of sialic acids.

Five new methods, based upon the selective oxidation of sialic acid residues with 0.4 mM periodic acid in approximately 1 M hydrochloric acid at 4 degree C for 1 h (PA), have been devised for the simultaneous visualization of neutral sugars and either sialic acid and its side chain O-acyl variants or O-sulphate ester. In the first of these, the selective periodate oxidation-borohydride reduction-saponification-selective periodate oxidation-Thionin Schiff-saponification-borohydride reduction-periodic acid-Schiff (PA-Bh-KOH-PA-T-KOH-Bh-PAS) technique, sialic acids with O-acyl substituents at C7, C8 or C9 (or which have two of three side chain O-acyl substituents) stain blue while neutral sugars with periodate-sensitive vicinal diols (hexose, 6-deoxyhexose, and N-acetylhexosamine) stain magenta. The second method, the saponification-selective periodate oxidation-Thionin Schiff-saponification-borohydride reduction-periodic acid-Schiff (KOH-PA-T-KOH-Bh-PAS), stains all sialic acids blue and neutral sugars magenta. In the third procedure, the selective periodate oxidation-Thionin Schiff-borohydride reduction-periodic acid-Schiff-saponification (PA-T-Bh-PAS-KOH) method, sialic acids without side chain substituents (or which have an O-acyl substituent at C7) stain blue and neutral sugars stain magenta. In the fourth method, the saponification-selective periodate oxidation-borohydride reduction-Alcian Blue pH 1.0-periodic acid-Schiff (KOH-PA-Bh-AB1.0-PAS) technique, O-sulphate esters stain aquamarine blue and neutral sugars stain magenta. In all of these techniques mixtures of the components stain in various shades of purple.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Substances with alpha-melanotropin-like immunoreactivity in bovine brains.

1. Bovine cerebral hemispheres were extracted with an acidic medium (acetone-water-hydrochloric acid mixture, 40:5:1 by volume, pH 1.8). The precipitate which formed upon addition of a copious volume of cold acetone to the extract was designated acid acetone powder (AAP). 2. The AAP was then subjected to ion exchange chromatography on carboxymethyl (CM)-cellulose, gel filtration on Sephadex G100 and Sephadex G25, second ion exchange chromatography on CM-cellulose and high performance liquid chromatography. The absorbance of all fractions was measured at 280 nm and their alpha-melanotropin-(alpha-MSH)-like immunoreactivity was monitored with radioimmunoassay. 3. It was found that alpha-MSH-like immunoreactivity and bioactivity (lipolytic activity) was due to low molecular weight materials as evidenced by their retardation on Sephadex G-100 and Sephadex G-25. The immunoreactivity was distributed among fractions adsorbed and fractions unadsorbed on CM-cellulose and also among high performance liquid chromatographic fractions signifying the presence of multiple alpha-MSH-like molecules.

Animals↗
PubMed1977

3alpha-Hydroxy-5beta,14beta-chol-8-en-24-oic acid and its isomer, dehydration products of chenodeoxycholic acid obtained by treatment with concentrated HC1.

3alpha, 7alpha-Dihydroxy-5beta-cholan-24-oic acid in acetic acid was treated with concentrated hydrochloric acid at room temperature. Two of the dehydration products thus obtained proved to correspond to the beta- and gamma-acids reported (5). One (gamma-acid) of these was identified as 3alpha-hydroxy-5beta, 14beta-chol-8-en-24-oic acid (IIa) by means of several spectral measurements of itself and its OsO4 oxidation products. Chemical structure of the other (beta-acid) remains undetermined.

Chemical Phenomena↗
PubMed1995

A rapid method for the detection of uranium in surface water.

A method has been optimized to preconcentrate uranium from waters using the ion exchanger Hyphan. The sample (up to 10 1) is agitated thoroughly with a portion of the ion exchanger for between 40 min and 2 h. The exchanger is filtered off and treated with a small volume (< 100 ml) of either nitric acid (for ICP measurement) or hydrochloric acid (for alpha measurement). The acid is filtered off and measured directly by ICP-AES, or it is brought to pH 2 and saturated with ammonium chloride, then directly electrolyzed. Yields lie in the order of 60-90% and the overall analysis time is approximately 3 h (ICP) or approximately 4 h (alpha measurement). Precisions reached are better than 15% relative. Detection limits lie at about 2 ppb (ICP) and 0.4 ppb (alpha measurement).

Fresh Water↗
PubMed1982

The molecular nature of vascularly released cholecystokinin from the isolated perfused porcine duodenum.

Using sequence-specific radioimmunoassays, the quantities and molecular nature of cholecystokinin (CCK) have been determined in extracts of porcine duodenal mucosa and in the vascular perfusate from the isolated porcine duodenum. The basal concentration of CCK in the perfusate was 84 pM equiv. CCK-8 (mean; range: 32-173 pM, n = 5). After intraluminal stimulation with amino acids, acidified fat emulsions and hydrochloric acid, the concentrations increased 2--5-fold. Both in the basal and stimulated state the concentrations of the related hormone, gastrin, were below 5 pM equiv. gastrin-17. CCK in the perfusate was concentrated by affinity-chromatography using antibodies directed against the bioactive C-terminus. Subsequent gel chromatography revealed a form with a size like or slightly larger than the C-terminal dodecapeptide (CCK-12), a predominant form resembling the C-terminal octapeptide (CCK-8), and a form resembling the C terminal tetrapeptide (CCK-4). The duodenal mucosa contained in addition CCK-33, -39 and CCK-peptides with further N-terminal extensions. The results suggest that small CCK peptides are the principal circulating forms, while CCK-33 and larger forms are biosynthetic precursors.

Amino Acid Sequence↗