Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. In six volunteers, the effect of intragastric administration of different water-soluble chemical isolates of dietary fibre on gastric secretion, acidity and emptying was studied. 2. At 30 min after administration of the test meals, the stomach contents were completely aspirated and the volume, pH, phenol red concentration, total titratable acidity and different electrolytes were measured. 3. Compared with the control meal, the pH and unionized (combined) hydrogen concentrations were significantly higher (P less than 0.05) following most of the fibre-containing meals, while the total titratable acid concentration was not significantly different. None of the fibre-containing meals appreciably altered the volume or type of gastric secretion but had a low-grade variable effect on gastric emptying. 4. It is concluded that most dietary fibre isolates, although having a definite and notable buffering effect on the acid in the stomach, have a minimal effect on gastric secretion and a variable and small effect on gastric emptying.
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PMID:The effect of dietary fibre isolates on gastric secretion, acidity and emptying. 282 69

High-fiber diets are being recommended by government agencies, cancer institutes, and manufacturers of high-fiber foods. Although this recommendation is appropriate for the majority of clients, some persons are prone to form phytobezoars and should not add certain kinds of fiber to the diet. The phytobezoar is a compact mass of fibers, skins, seeds, leaves, roots, or stems of plants that collects in the stomach or small intestine. Other food particles, such as fats, crystals, granules, fibers, and residues of salts, are incorporated into the mass and contribute to the growth of the bezoar. Clients who have undergone surgical procedures for peptic ulcer disease or stomach cancer or who for other reasons, such as diabetic gastroparesis, have a loss of normal pyloric function and decreased gastric acidity are prone to form phytobezoars. Once formed, the bezoar can be disintegrated through surgery, by the use of the Water Pik and enzymes during endoscopy, or by treatment with metoclopramide. The dietitian should advise such clients to avoid identified foods that lead to phytobezoar formation--oranges, persimmons, coconuts, berries, green beans, figs, apples, sauerkraut, brussels sprouts, and potato peel.
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PMID:Foods high in fiber and phytobezoar formation. 282 90

The first part of the study consisted of 110 rats in 11 groups with ten rats in each. Nine of the groups were fed nutrient solutions of different compositions, antacid and sucralfate through orogastric tube during induction of stress ulcer by restraint and a cold ambient temperature. One group served as a control group and received no feeding and the 11th group was given cimetidine intraperitoneally. The extensiveness of the stress effect was estimated in each group by the number of rats with ulcer as percentage, the mean number of ulcers in each rat, the mean distribution of ulcers of different sizes, the mean total of mucosal damage in each rat and the contribution of ulcers of a different size to the total mucosal damage. The results showed that cimetidine is an effective protector against stress ulcer. Guar gum, Intralipid (fat emulsion), egg protein and 30 per cent glucose are slightly weaker protectors than cimetidine but much stronger than 10 per cent glucose wheat flour and distilled water. Sucralfate increased the susceptibility to stress ulcer. The second part of the study consisted of 86 rats. It showed, that guar gum increased the healing rate of stress ulcers. During a 30 hour treatment period after four hours of stress, the rats fed guar gum (n = 30) showed a lower (p less than 0.001) number of ulcers than the control rats fed normal rat food (n = 26) or immediately after the four hours of stress (n = 30). The mechanisms suggested for ulcer prevention and increased ulcer healing rate found herein may be due to reduced acidity, increased local mucosal supply of energy and mechanical protection.
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PMID:The protective effect of nutrients against stress induced gastric ulcers in the rat. 282 67

1. Enrichment in the (S)-enantiomers for (R)-flurbiprofen, (R)-naproxen, (R)-suprofen and (R;S)-ibuprofen was investigated in various subcellular hepatic preparations containing coenzyme A. While such preparations were able to form hippuric acid from benzoic acid, the chiral inversion was never seen. 2. Using 2-dimethylaminoethanethiol 2-phenylpropionate (DEPP) as a model acyl thioester, the acidity of the methine proton was investigated by monitoring the proton/deuterium exchange occurring in deuterated solvents using high-resolution n.m.r. The compound was inert up to 22 h in D2O at 37 degrees C and pD 7.4. In pure methanol or a methanol-water mixture, only solvolysis was seen. In contrast, competitive hydrolysis (k = 0.005 h-1) and proton/deuterium exchange (k = 0.09 h-1) were seen in a CD3CN/D2O (50:50) mixture at 37 degrees C. 3. It is speculated that the failure to characterize chiral inversion of 2-arylpropionates in subcellular preparations may be due to the absence of a microenvironment of adequately moderate polarity.
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PMID:Metabolic chiral inversion of anti-inflammatory 2-arylpropionates: lack of reaction in liver homogenates, and study of methine proton acidity. 284 Jul 82

Atmospheric gaseous pollutants (NO2, SO2, NH3, HNO3) and related ionic species in water-soluble fine particulates and rainwater were monitored from September 1986 to January 1987 with the aim of estimating the acid deposition over a rural area near Rome. A wet-only rain collector and an annular denuder-filter pack sampling system for gases and aerosols were employed to avoid chemical artifact formation. A comparison of the wet and dry deposition rates indicates that atmospheric removal by precipitation was the dominant sink for sulfate and nitrate at the sampling site. Ion balance analysis showed that the main compounds present in aerosols were (NH4)2SO4 and NH4NO3, since the ammonium neutralization factor approached 100% and the acidity content was very low. The marked enrichment of H+, SO4(2-) and NO3- in precipitation compared with NH4+ could be explained by assuming either that SO2 and NO2 are oxidized in cloud droplets or that acidic sulfate and nitrate are scavenged directly in-cloud or below-cloud.
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PMID:Characterization of a rural area in terms of dry and wet deposition. 285 79

Several divalent metal ions were used as kinetic probes of the beef heart mitochondrial adenosinetriphosphatase (F1) under a variety of conditions, and the relationship between the properties of the catalytic metal ion and the catalytic activity of the enzyme was examined. Vmax for ATP hydrolysis was largest when metal ions characterized by intermediate values of acidity of coordinated water molecules (pKa) and metal-nucleotide stability constants (Kstab) were present. As temperature increased, the peak of Vmax vs. pKa (or Kstab) shifted to lower initial values of pKa or Kstab. The solvent deuterium isotope effect on Vmax (DV) was normal and largest when the metal ion present during F1-catalyzed ATP hydrolysis was most acidic and the metal nucleotide stability constant was large. When an active site tyrosine on F1 was nitrated, Vmax was most affected when the metal ion present was least acidic and the metal nucleotide stability constant was small. The isotope effect on V/K (DV/K) was normal, small, and apparently independent of the metal ion present. ADP inhibition of F1-catalyzed ATP hydrolysis is competitive, and the Ki is independent of the metal ion present. The degree of Pi inhibition of F1 is dependent on the metal ion present. The inhibition by Pi is competitive at low temperature and becomes noncompetitive as temperature increases. These and previous results support a mechanism whereby a water molecule coordinated to the metal ion of an enzyme-bound gamma-monodentate metal-ATP complex is deprotonated to begin a series of events whereby a beta,gamma-bidentate metal-ATP complex is produced. Upon hydrolysis, the bond between the metal ion and the beta-phosphate of ADP in the Pi-metal-ADP complex is broken before products (ADP and metal-Pi) are released.
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PMID:Dependence of the activity of beef heart mitochondrial adenosinetriphosphatase on the properties of the catalytic metal ion. 288 48

This report summarizes a study of the chemical and biological characteristics of three oligotrophic lakes located in a region that receives a moderately acidic precipitation (mean annual pH 4.5-4.6), and a sulfate deposition of about 20 kg/ha/yr. The two brownwater lakes are relatively acidic (pH 4.5 and 4.8), and much of their acidity is attributable to organic anions. The brownwater lakes also have a large concentration of aluminum and iron, but these are bound to dissolved organic matter and are relatively non-toxic to biota. Average phytoplankton production was largest in the clearwater lake. This was due to its relatively deep euphotic zone, since the average unit-volume productivity did not differ much among the lakes. In fact, productivity at light optimum was largest in the most acidic brownwater lake, probably because of its larger phosphorus concentration. The clearwater lake had extensive macrophyte vegetation, which covered its bottom to a depth of 6.5 m. In the brownwater lakes, macrophytes were confined to shallow nearshore water because of the limited water transparency. Zooplankton density and biomass were largest in the most acidic brownwater lake, probably because of allochthonous organic particulates and little fish predation. Benthic invertebrates were abundant in all three lakes, and were dominated by insects, especially Chironomids. Lakes in the study area appear to be sustaining fish populations at more acidic pHs than elsewhere. This may be due to the large concentration of dissolved organic matter in many lakes, which complexes and partially detoxifies metals such as aluminum.
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PMID:Characteristics of three acidic lakes in Kejimkujik National Park, Nova Scotia, Canada. 292 90

The toxicity of 31 phenols was studied by electro-rotation of yeast cells. Control yeast cells show both anti-field and co-field rotation, depending upon the field frequency applied. After treatment with supra-threshold amounts of phenols the anti-field rotation is weakened or abolished and a stronger co-field rotation can be seen. The proportion of cells showing the co-field rotation was found to be a sensitive measure of toxicity. Doses of 2.2 mumol/l of pentachlorophenol, or of 0.3 mumol/l of pentabromophenol were detectable after 3 h incubation at pH 4.0. At a given pH, the toxicity of the chlorophenols correlated extremely well with their octanol:water partition coefficients (Pow). The complete set of phenols showed fair overall correlation with Pow, but less good correlation with their acidity constants (pKa). In particular the toxicity of a given phenol was less than predicted from its pKa if the incubation pH was higher than the pKa. Biochemical assays on 23 of the phenols showed that the rotational sensitivity runs closely parallel to the sensitivities of cell growth rate and of the plasmamembrane ATPase, but less closely to the inhibition of purine incorporation. It appears that the electro-rotation method provides a useful and rapid test for the presence of organic ecotoxins. The test enables us to distinguish differences between single cells, and is comparable in sensitivity to biochemical tests that use vesicles or homogenates derived from a cell population.
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PMID:The comparative influence of substituted phenols (especially chlorophenols) on yeast cells assayed by electro-rotation and other methods. 296 20

When ingested 1 hour after a meal, conventional liquid antacids have a buffering effect of approximately 2 hours, while in the fasting state their effect is brief, lasting less than 1 hour. We tested the hypothesis that equal doses of antacid, one water soluble (sodium bicarbonate) and the other water insoluble (aluminum hydroxide plus magnesium hydroxide, MaaloxR), would have similar durations of postprandial buffering if the water soluble antacid regenerates the particulate protein buffer of the meal that leaves the stomach more slowly than liquids. Tests were conducted in random order on three separate days in 10 patients with duodenal ulcer. The effects of 30 ml of 2.39 M sodium bicarbonate (6.17 g, about 1 teaspoonful), the aluminum-magnesium antacid, each equivalent to 71.7 mmol of in vitro buffer, and water as a control on pH, hydrogen ion activity, and titratable acidity were compared. Thirty milliliters of each was swallowed 1 and 3 hours after ingestion of a standard solid plus liquid. Compared to the water control each dose of sodium bicarbonate significantly increased intragastric pH and decreased hydrogen ion activity and titratable acidity for only 1 hour. Each dose of the aluminum-magnesium antacid significantly buffered intragastric contents for 2 hours. These findings indicate that sodium bicarbonate transiently buffers postprandial intragastric contents. Therefore, sodium bicarbonate fails to reconstitute the protein buffer of the meal effectively, and the observations suggest that it leaves the stomach rapidly with the liquid phase of the meal. However, the water insoluble, aluminum-magnesium antacid has a longer duration of buffering, probably because it leaves the stomach more slowly, largely with the solid portion of the meal.
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PMID:The effect of sodium bicarbonate versus aluminum-magnesium hydroxide on postprandial gastric acid in duodenal ulcer patients. 301 68

Acetazolamide (Diamox) induced carbonic anhydrase inhibition is an efficient means of eliminating surplus water and bicarbonate in the overhydrated and alkalotic patient. Previous studies have demonstrated an unexpected and unexplained increase in arterial and venous oxygenation during acute carbonic anhydrase inhibition. In the present investigation we assessed the effect of acetazolamide 15 mg kg-1 on pulmonary gas exchange in 10 critically ill, mechanically ventilated patients. Median arterial oxygen tension increased by 0.9 kPa and central venous oxygen tension and content by 16-18% and 6-8% respectively. The improved oxygenation could, however, not be attributed to an improved pulmonary oxygen exchange as both pulmonary venous admixture (Qs Qt-1) and physiological dead space ventilation (VD VT-1) increased. The increase in arterial oxygen tension can be explained by a rightward shift of the oxyhemoglobin dissociation curve due to the increased acidity of the blood during carbonic anhydrase inhibition (Bohr effect). Acetazolamide does not depress oxygen consumption, so the increase in central venous oxygen content probably reflects an improved cardiac performance. This could conceivably be mediated via sympathetic activation in response to acetazolamide induced carbon dioxide retention.
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PMID:Respiratory function and carbonic anhydrase inhibition. 311 60


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