Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:6.3.4.6 (urease)
7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rise in serum gastrin and pepsinogen I after 5 days' treatment with the proton pump inhibitor pantoprazole (40 mg/day) was examined in eight duodenal ulcer patients with Helicobacter pylori infection and compared with eight in whom it had been eradicated. Before treatment, the post-prandial serum gastrin concentrations were higher in the H. pylori-positive than -eradicated patients (p less than 0.05). The median rise in pre-prandial serum gastrin concentrations on treatment was similar in the H. pylori-positive (41%) and -eradicated patients (45%). The rise in post-prandial serum gastrin was also similar in the H. pylori-positive (81%) and -eradicated patients (69%), resulting in significantly higher gastrin concentrations during treatment in the former. The median rise in serum pepsinogen I on treatment was greater in the H. pylori-positive (114%) than in the -eradicated patients (8%), resulting in significantly higher concentrations during treatment in the former. These observations indicate that eradication of H. pylori may be a means of moderating the hypergastrinaemia caused by acid-inhibitory therapy. They also indicate that H. pylori-related hypergastrinaemia is not due to an increase of the antral surface pH by the bacterium's urease activity.
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PMID:Helicobacter pylori and hypergastrinaemia during proton pump inhibitor therapy. 153 64

Eradication of Helicobacter pylori is associated with a fall in serum gastrin but the way in which the infection raises the serum gastrin concentration is not clear. It may be related to the ammonia produced by the bacterium's urease stimulating gastrin release by the antral G cells. Alternatively, the antral gastritis induced by the infection may modify the regulation of gastrin release. We have examined serum gastrin in 10 patients before and 24 hours after starting triple anti-H pylori treatment consisting of tripotassium dicitrato bismuthate 120 mg four times daily, metronidazole 400 mg three times daily, and amoxycillin 500 mg three times daily. The urease activity, assessed by the 20 minute value of the 14C-urea breath test, fell from a median of 176 (range 116-504) kg% dose/mmol CO2 x 100 pretreatment to 5 (2-15) at 24 hours (p less than 0.005). The median antral gastritis score was 6 (4-6) pretreatment and fell to 3 (2-5) at 24 hours (p less than 0.02), and this was due to resolution of the polymorphonuclear component. Despite this complete suppression of bacterial urease activity and partial resolution of antral gastritis the median basal gastrin concentration remained unchanged, being 57 ng/l (45-77) pretreatment and 59 ng/l (45-80) at 24 hours and the median integrated gastrin response to a standardised meal was also unaltered, being 4265 ng/l/min (range 1975-8350) and 4272 ng/l/min (range 2075-6495) respectively. These findings do not support a causal association between H pylori urease activity and hypergastrinaemia and show rapid improvement of antral gastritis after starting anti-H pylori treatment.
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PMID:Is Helicobacter pylori associated hypergastrinaemia due to the bacterium's urease activity or the antral gastritis? 175 56

The mechanism of the hypergastrinaemia associated with Helicobacter pylori infection is unknown. It may be an effect of the ammonia produced by the bacterium near the antral epithelial surface. We have examined the effect on serum gastrin of inhibiting H pylori urease activity with acetohydroxamic acid in six duodenal ulcer patients. On day 1 the fasted patients received placebo tablets at 8 am, a peptide meal at 10 am, and a 14C urea breath test at 11.30 am. The next day 750 mg acetohydroxamic acid was administered orally in place of the placebo. The median (range) 30 minute breath test value (dose/mmol CO2 X kg body wt X 100) was 152 (111-335) on day 1, but only 22 (14-95) the next day (p less than 0.03). Further studies performed in one subject confirmed that acetohydroxamic acid lowered the ammonium concentration and raised the urea concentration in gastric juice. The inhibition of urease activity and ammonia production did not result in a fall in the basal gastrin concentration or in the median integrated gastrin response to the peptide meal, which was 78 ng/1.h (range 21-222) on day 1 and 79 ng/1.h (33-207) the next day. Ten days after acetohydroxamic acid, the urea breath test values were similar to those before treatment. This study shows that the raised gastrin concentration in patients with H pylori infection is not directly related to the organism's urease activity. It also shows that temporary suppression of H pylori urease activity does not clear the infection.
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PMID:Effect of inhibition of Helicobacter pylori urease activity by acetohydroxamic acid on serum gastrin in duodenal ulcer subjects. 188 67

In a prospective study, eight young healthy subjects (five with an active H. pylori infection in the antral mucosa) were treated with a course of tripotassium dicitrato bismuthate, amoxycillin and metronidazole. The triple therapy eradicated infection when assessed 20-24 weeks later by antral biopsy (urease, histology, and 13C urea breath test [4 out of 5 subjects]). Twenty-four hour intragastric acidity and plasma gastrin concentration were measured before treatment, and 4-6 weeks and 20-24 weeks post-treatment. Treatment did not affect acidity in either the H. pylori-positive or H. pylori-negative groups, nor did it affect the plasma gastrin profile in the H. pylori-negative group. Eradication of H. pylori infection in five subjects caused a drop of the median integrated 24-hour plasma gastrin concentration from 558 pmol.h/L before treatment to 307 and 289 pmol.h/L at 4-6 and 20-24 weeks post-treatment, respectively. It is concluded that H. pylori infection is associated with 24-hour hypergastrinaemia, and that in apparently healthy subjects normal gastric physiology can be restored by eradication of the infection.
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PMID:Eradication of Helicobacter pylori abolishes 24-hour hypergastrinaemia: a prospective study in healthy subjects. 188 27

It has been proposed that the hypergastrinaemia in subjects with Helicobacter pylori infection is caused by the action of the ammonia produced by the organism's urease activity on the antral G cells. To investigate this hypothesis we examined the effect on plasma gastrin of increasing the bacterium's ammonia production by infusing urea intragastrically to eight H pylori positive duodenal ulcer patients. After a 60 minute control intragastric infusion of dextrose solution at 2 ml/minute, a similar infusion containing urea (50 mmol/l) was continued for four hours. During the urea infusion, the median gastric juice urea concentration rose from 1.1 mmol/l (range 0.3-1.6) to 15.5 mmol/l (range 7.9-21.3) and this resulted in an increase in the ammonium concentration from 2.3 mmol/l (range 1.3-5.9) to 6.1 mmol/l (range 4.2-11.9) (p less than 0.01). This appreciable rise in ammonia production did not result in any change in the plasma gastrin concentration. The experiment was repeated one month after eradication of H pylori, at which time the median basal gastrin was 20 ng/l (range 15-25), significantly less than the value before eradication (30 ng/l range 15-60) (p less than 0.05). On this occasion, the gastric juice ammonium concentration was considerably reduced at 0.4 mmol/l (range 0.1-0.9) and the urea infusion did not raise the ammonium concentration or change the plasma gastrin concentration. In conclusion, augmenting H pylori ammonia production does not cause any early change in plasma gastrin.
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PMID:Effect of increasing Helicobacter pylori ammonia production by urea infusion on plasma gastrin concentrations. 199 33

Recent studies have shown that the exaggerated meal-stimulated gastrin release in patients with duodenal ulcer abates after eradication of Helicobacter pylori infection. Bombesin-stimulated gastrin release was compared in 11 H. pylori-infected patients with chronic duodenal ulcer and 8 uninfected healthy volunteers both before and after therapy to eradicate H. pylori. Bombesin infusion significantly increased the gastrin release both in control subjects and in patients with duodenal ulcer. Antimicrobial therapy (bismuth, tetracycline, and metronidazole) to eradicate the H. pylori infection was associated with a significant reduction in bombesin-stimulated gastrin release in patients with duodenal ulcer (from 116.9 +/- 19 pg/mL to 69.5 +/- 7 pg/mL following 50 pmol.kg-1.h-1 bombesin; and from 158 +/- 29 to 83.4 +/- 10 following 200 pmol.kg-1.h-1 bombesin: P = 0.01 for each). Antimicrobial therapy had no effect on gastrin release in uninfected volunteers, thus excluding a nonspecific effect of antimicrobial therapy on antral G-cell function. Serum gastrin was also not increased by feeding 500 mg of urea to 5 H. pylori-infected volunteers. This suggests that access of hydrogen ion to the pH-sensitive sites governing gastrin release by mucosal ammonia produced by H. pylori urease is not a critical factor. These data suggest that exaggerated gastrin release present in patients with duodenal ulcer disease is secondary to H. pylori infection.
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PMID:Helicobacter pylori-associated exaggerated gastrin release in duodenal ulcer patients. The effect of bombesin infusion and urea ingestion. 201 63

Little is known about the source and spread of Helicobacter pylori, but transmission from infected family contacts has been suggested. We have therefore investigated 15 children with peptic ulcer and their first-degree relatives for H. pylori. Serum anti-H. pylori IgG, pepsinogen I, and gastrin levels were measured. Endoscopy was carried out on the children and relatives, and biopsies were taken from the gastric antrum for histology, microbiology, and urease testing. Six of 11 children with duodenal ulcer (55%) and two of four children with gastric ulcer (50%) were positive for H. pylori. Fourteen of 16 parents (87%) and eight of 13 siblings (61%) of H. pylori-positive children with peptic ulcer were also infected compared with eight of 14 parents (57%) and none of four siblings of H. pylori-negative children with peptic ulcer (P less than 0.10, greater than 0.05, and NS, respectively). The children with H. pylori-negative peptic ulcer and negative siblings combined were younger than positive children with peptic ulcer and positive siblings (P less than 0.001). The reliability of serum anti-H. pylori IgG level as a screening test for infection was confirmed. These findings call into question a pathogenetic role for H. pylori in some childhood peptic ulceration, but do suggest that person-to-person spread of infection occurs.
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PMID:Helicobacter pylori in children with peptic ulcer and their families. 202 57

Campylobacter pylori (C.p.) infection is often found in patients with antral gastritis and peptic ulcer disease. Pathophysiological links are still unclear, and we therefore tested the hypothesis whether C.p. affects the gastrointestinal peptides and thus influences gastric acid secretion and protective factors. 94 patients were examined by upper GI endoscopy and blood analyzed for gastrin, somatostatin, pancreatic polypeptide and neurotensin. Biopsies of antral mucosa were investigated for C.p. in urease testing, culture and microscopy. C.p. was found in 42 patients (45%). In microscopy all of these patients had chronic gastritis (100%). A significant increase in gastrin uninfluenced by C.p. was found in patients with antral gastritis (normal: 6.4 +/- 0.7, [n = 27]; gastritis without C.p.: 18.4 +/- 5.9 [p less than 0.02], [n = 7]; gastritis with C.p.: 10.7 +/- 2.2, [n = 22]). Somatostatin, pancreatic polypeptide and neurotensin showed no difference.
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PMID:[Campylobacter pylori colonization of the antrum: effect of gastrin, somatostatin, pancreatic polypeptide and neurotensin]. 256 33

Although an association is suggested between gastric cancer and prior infection with Helicobacter pylori (HP), the role of HP in gastric carcinogenesis remains obscure. HP has potent urease activity and produces ammonia, a factor causing HP-related gastroduodenal mucosal lesions. In this study, rats were examined in an effort to determine effects of ammonia on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). After pretreatment with MNNG (83 mg/l) for 24 weeks, a solution of either 0.01% ammonia or plain tap water was administered to the animals as drinking water for an additional 24 weeks. The administration of the 0.01% ammonia solution significantly increased the incidence and number of cancers in the glandular stomach. The numbers of cases in which these cancers penetrated the muscle layer or deeper and of low-grade differentiated adenocarcinomas were significantly higher in rats receiving the ammonia solution. Continuing administration of ammonia accelerated cell proliferation in the gastric mucosa, but had no effect on the serum gastrin level. Therefore, gastric ammonia, which stimulates mucosal cell proliferation, appears to be an important promoter in carcinogenesis in rats and possibly in the HP-related gastric carcinogenesis in humans.
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PMID:Mechanism for ammonia-induced promotion of gastric carcinogenesis in rats. 769 14

Helicobacter pylori is a microaerophilic bacterium initially found in the gastric antrum of patients with peptic ulcer disease. As a result, H. pylori is now believed to have a pathophysiologic role in gastritis as well as in peptic ulcer disease. Several recent studies showed that it may be associated with duodenal ulcer relapse and that eradication therapy using antibiotics may significantly decrease the ulcer recurrence rate in duodenal ulcer patients. Moreover, epidemiological studies suggest that it may increase the relative risk of carcinoma in the stomach and preliminary studies seem to indicate that some low-grade lymphoma in the stomach may regress after H. pylori eradication. Although the mechanisms by which H. pylori induces mucosal injury and/or neoplasm is not clearly understood, several modifications in gastric functions have been reported. The most specific way of detecting H. pylori in tissue is a combination of culture and histologic staining of mucosal biopsy specimens obtained by endoscopy. Rapid urease test, cytology and PCR procedures performed on biopsies may give rapid, sensitive and specific results. Breath test using 13C- or 14C-radiolabelled urea and serology tests are of particular importance when H. pylori diagnosis is needed via no invasive procedures. Helicobacter pylori is supposed to interact with G and D cells. Gastrin and somatostatin are synthetized and released from antral G and gastric D cells respectively. The gastric D cells are in close contact with either G and parietal cells. Gastrin stimulates gastric acid secretion and epithelial gastric cell proliferation (parietal and EC-L cells) while somatostatin inhibits these effects. Chronic gastritis is associated with fundic duodenal ulcer disease. In this situation, basal gastrin and meal- or bombesin-stimulated gastrin in the serum (especially gastrin G17) have been found to be higher in H. pylori positive than in negative patients. Moreover, gastrin decreases up to normal levels after eradication of H. pylori. The long term effect of a such hypergastrinemia is not so far established. The mechanism underlaying hormonal modification is poorly understood. Since no G/D cell ratio modification could be found after H. pylori eradication while the amount of somatostatin increases, one would suggest functional alteration of either G or D cells in the H. pylori-related chronic gastritis. The role of inflammatory mediators on the gastrin release and the processing of progastrin induced by the bacterium need further investigations.
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PMID:[Helicobacter pylori, a rediscovered bacterium. Implication in gastroduodenal diseases]. 789 50


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