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Query: UMLS:C0847097 (acidity)
 15,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Upon experimental metabolic acidosis in rats, induced by a long-term per os administration of a 10% ammonium chloride solution, elevation of titred acidity and ammonium level in rat's urea was registered, in addition to an increased number of intercalated cells in collecting tubules of kidney medullar zone, where the highest carboanhydrase activity occurred. The structural and functional unit of the intercalated cell is a smooth vesicle having presumable H+-,K+-translocating exchange pump within its membrane. The vesicles accumulating gradually H-ions move to the apical cell membrane to release their content by exocytosis into the tubule space. Under H+-ion hypersecretion, upon experimental acidosis, the vesicle membrane is built into the apical plasma membrane, where H+,K+-exchange occurs, thus intensity of this process increasing. The apical plasma membrane of the cell extends its surface at the expense of intracellular canaliculi that are formed.
Tsitologiia 1988 Sep
PMID:[The role of the ultrastructure of the intercalated cells of the kidney collecting tubules in rats in secreting hydrogen ions]. 321 72

In a randomized trial of gastric pH control for stress ulcer prophylaxis, 200 mg/day ranitidine iv was compared to antacids in 86 patients admitted to an ICU. Six (15%) patients receiving ranitidine and six (13%) given antacids failed to maintain greater than 50% of the hourly gastric pH measurements at or above 4. Increasing the ranitidine dosage to 300 mg/day did not provide additional control. One patient in the antacid group developed an overt upper GI bleed secondary to endoscopically proven erosive disease. We conclude that iv ranitidine in a dosage of 200 mg/day is as effective as antacids in reducing gastric acidity and preventing stress ulcer disease in critically ill patients.
Crit Care Med 1987 Sep
PMID:A randomized clinical trial comparing ranitidine and antacids in critically ill patients. 330 37

The circadian pattern of intragastric acidity was assessed in 19 healthy subjects and 37 patients with active, endoscopically proven duodenal ulcer using 24-hr continuous intraluminal pH-metry. The median pH 24-hr profiles showed that ulcer patients had lower postprandial pH elevations and a smaller decline in acidity during the early morning hours when compared with controls. The after-lunch and -dinner area under the curve and maximum pH values were significantly higher in controls compared to ulcer patients. In the nighttime, the median pH values in controls were significantly higher during 9 PM to 12 PM (P = 0.02), 12 PM to 4 AM (P = 0.01), and 4 AM to 8 AM (P = 0.0008) compared to the ulcer patients. We conclude that the 24-hr acidity is higher in ulcer patients compared to healthy subjects and that the differences are particularly evident in the postprandial and nocturnal periods.
Dig Dis Sci 1988 Sep
PMID:24-hour study of intragastric acidity in duodenal ulcer patients and normal subjects using continuous intraluminal pH-metry. 340 94

The purpose of these studies was to determine the role played by endogenous prostaglandins in the development of gastric ulcers produced by indomethacin, and of duodenal ulcers produced by mepirizole in rats. Indomethacin (10 mg/kg subcutaneously) produced gastric ulcers, whereas mepirizole (100 mg/kg subcutaneously) produced exclusively duodenal ulcers. Both drugs, given at ulcerogenic doses, reduced the gastric and duodenal generation of PGE2, PGF2 alpha, 6-keto-PGF1 alpha, and thromboxane B2. In this regard, the extent of reduction was more pronounced after indomethacin than after mepirizole. Despite this greater inhibition of prostaglandin synthesis by indomethacin, this drug did not produce duodenal ulcers, whereas mepirizole was duodenoulcerogenic. In addition, mepirizole increased gastric acid secretion by 74%, whereas indomethacin had no effect on acid secretion. Oral administration of 16,16-dimethyl PGE2, given at nonantisecretory doses (0.5-5 micrograms/kg), prevented formation of indomethacin-induced gastric ulcers, whereas antisecretory doses were required to prevent formation of mepirizole-induced duodenal ulcers. We conclude that a reduction of prostaglandin formation in the duodenal mucosa is not by itself sufficient to induce duodenal ulcers. We hypothesize that three changes, produced by mepirizole, must be present for duodenal ulcers to develop: increased gastric acid secretion, decreased duodenal bicarbonate secretion (as demonstrated earlier), and decreased duodenal content of prostaglandins. The decreased prostaglandin formation, although not causing duodenal ulcers, may lower the resistance of duodenal mucosa to the hyperacidity induced by mepirizole. On the other hand, in the case of gastric ulcers following administration of indomethacin, a decrease in gastric mucosal levels of prostaglandins may play a more important role than changes in gastric acidity.
Dig Dis Sci 1987 Sep
PMID:Prostaglandin deficiency by itself is not the cause of mepirizole-induced duodenal ulcers in rats. 362 95

The acidification of urine during polyol feeding was investigated with 27 Long-Evans male rats (aged 12 weeks) which were fed a xylitol diet (X), a sorbitol diet (S), or a basal diet for 4 weeks. The amount of polyols in the diet was increased from 5% to the final 20% level within 3 weeks. The polyol-fed animals showed reduced weight gain, lowered urine pH (from 6.5 to 5.6), and a 4-fold increase in the titratable acid excretion. X and S increased the daily urine volumes by 49 and 63%, respectively, but did not affect the wet weight or the pH values of the feces. as chromatographic-mass spectrometric analyses of organic acids revealed highly increased amounts of methylmalonic acid (13- to 20-fold) and 2-oxoglutaric acid (4- to 5-fold) in the urine of polyol-fed rats. The urinary excretion of citric acid and malic acid was also increased significantly (2- to 4-fold). The acidity of urine was not reflected in the blood acid-base balance of the animals. The increases in the levels of urinary organic acids in the polyol-fed rats were explained in terms of impaired mitochondrial oxidation of these acids and of impaired conversion of methylmalonic acid to succinic acid.
Toxicol Appl Pharmacol 1987 Sep 15
PMID:Organic aciduria in rats fed high amounts of xylitol or sorbitol. 362 97

The shapes of the distributions of gastric pH and hydrogen ion concentration [H+] were determined for each of 68 groups of patients scheduled for elective surgery under general anesthesia. The 68 groups comprised a total of 1,326 patients who had served as subjects in 13 of the authors' previously published studies. In general, the results showed that neither pH nor H+ was normally distributed; most of the pH distributions (47 of 68 = 69%) and most of the H+ distributions (53 of 68 = 78%) showed significant departure from the normal distribution. Moreover, the shapes of the distributions varied, depending upon the conditions under which gastric acidity was assessed. Groups receiving no medication for gastric acidity had positively skewed pH distributions (nonsymmetrical distribution with tail pointing to right and majority of cases in lower range), and groups receiving medications for the reduction of acidity had negatively skewed pH distributions (nonsymmetrical with tail pointing to left and majority of cases in upper range). The medications produced an inverse relationship between mean pH and skewness such that the skewness of the groups decreased from positive to negative as mean pH increased. For H+, all groups had positively skewed distributions, but the distributions were more positively skewed for groups receiving medications for gastric acidity. Again, the medication conditions produced an inverse relationship between mean acidity and skewness such that the groups became more positively skewed as the mean H+ decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesiology 1987 Sep
PMID:Evaluation and comparison of the distributions of gastric pH and hydrogen ion concentration. 363 13

Gastric ulcerations induced in rats by a combination of indomethacin and cold-stress (5 +/- 1 degrees C) for 6 hr were more severe than those induced by indomethacin or cold-stress alone. The acidity of gastric juice was increased in rats treated with indomethacin plus cold-stressed. Histamine H2 receptor antagonists, (H+-K+) ATPase inhibitors and prostaglandins inhibited gastric ulcer formation in indomethacin plus cold-stress treated rats, whereas anticholinergics aggravated the ulceration. The indomethacin plus cold-stress induced acid secretion was inhibited by cimetidine and omeprazole in pylorus-ligated rats. Atropine had less effect on the increase in acidity than cimetidine and omeprazole. These findings indicate that the ulcer formation in indomethacin plus cold-stress treated rats is related the increased in acidity of gastric juice. This gastric ulcer model may be useful for evaluating antiulcer agents.
Res Commun Chem Pathol Pharmacol 1987 Sep
PMID:Effects of indomethacin and cold-stress on gastric acid secretion and ulceration. The effects of anti-acid secretory agents in rats. 367 83

Thirty published studies of the clinical pharmacology of gastric antisecretory agents in normal volunteers and duodenal ulcer patients were reviewed. The aim was to investigate the relationship between antisecretory effect in the two populations. There was a significant correlation between effect in patients and normal subjects for suppression of 24 hour intragastric acidity (r = 0.732; p = 0.0068), nocturnal intragastric acidity (r = 0.861; p = 0.0033) and nocturnal acid output (r = 0.964; p = 0.0069). The regression lines for 24 hour and nocturnal acidity were very similar. The expected antisecretory effect of a particular dosage regimen in patients with duodenal ulcer can be predicted mathematically from data derived from studies in normal volunteers.
Gut 1986 Sep
PMID:Comparison of the effects of gastric antisecretory agents in healthy volunteers and patients with duodenal ulcer. 375 19

The influence of the pH of suspending medium on bovine neutrophil (PMN) function was assessed in tests of phagocytosis and killing of Staphylococcus aureus. Intracellular killing was markedly inhibited by moderate extracellular acidification whereas phagocytosis was little affected, except at the lowest pH level (pH 5.0). The killing of S. aureus by extracts of isolated PMN lysosomal granules showed a similar pH dependence and was optimal at pH levels above neutrality. Survival of S. aureus within PMN from different cows varied significantly and the relative differences in PMN bactericidal efficiency were maintained at all pH levels. The acidification of extracellular medium during incubation which resulted from metabolic activity of the PMN themselves, increased with increasing ratios of bacteria:PMN and varied significantly among cows. Addition of methylamine (10 mM) to elevate phagolysosomal pH inhibited phagocytosis and had no effect on intracellular survival of S. aureus. However, a lower concentration (1.5 mM) did not affect phagocytosis, but reduced bacterial survival without altering the relative differences in efficiency of PMN from different cows. It is suggested that the acidity of the extracellular medium may both reflect and influence the pH changes occurring within PMN phagosomes and, thereby, modulate the efficiency of intracellular destruction of S. aureus.
Vet Immunol Immunopathol 1986 Sep
PMID:The influence of extracellular and phagolysosomal pH changes on the bactericidal activity of bovine neutrophils against Staphylococcus aureus. 376 70

In 41 non-dyspeptic volunteers (18 females and 23 males) the fasting and food-stimulated serum gastrin concentration was investigated. No significant sex differences were found in the basal serum gastrin concentration. The integrated postprandial gastrin output, however, was significantly higher in females than in males. In 151 duodenal ulcer patients (31 women and 120 men) significant sex differences were found in both the fasting and the food-stimulated serum gastrin concentration. Women had values approximately 60% higher than men. In 116 of the patients (27 women and 89 men) the basal and pentagastrin-stimulated gastric acid concentrations were investigated. In the basal state no significant sex differences in acid output were found. After stimulation women had significantly lower gastric acidity and gastric acid output than men.
Scand J Gastroenterol 1986 Sep
PMID:Fasting and food-stimulated serum gastrin concentration in 151 duodenal ulcer patients and 41 non-dyspeptic volunteers. Significant sex differences. 377 53


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