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Biomedical subjects

A Wirz

Publications and source records attributed to A Wirz.

At least 19 recordsLinked to original sources
PubMed2005

Proton pump inhibitors reduce the bioavailability of dietary vitamin C.

BACKGROUND: The gastric juice concentration of vitamin C is reduced in subjects with elevated intragastric pH. This is probably because of the fact that the vitamin is unstable at non-acidic pH and undergoes irreversible denaturation. AIM: To determine whether elevation of intragastric pH reduces the bioavailability of dietary vitamin C. METHODS: Plasma vitamin C was measured before and after a course of omeprazole 40 mg/day for 4 weeks in 14 Helicobacter pylori positive and 15 H. pylori negative subjects. Dietary intake of vitamin C was measured and intragastric pH monitored. RESULTS: Compared with the H. pylori negative subjects, H. pylori positive subjects had a lower mean daily vitamin C intake (141.7 mg vs. 41.5 mg, P < 0.01) and also lower plasma vitamin C concentration (25.1 microg/mL vs. 17.4 microg/mL, P < 0.0001). After 28 days of 40 mg/day of omeprazole the mean plasma vitamin C level had fallen by 12.3% (P = 0.04). This fall affected both the H. pylori positive and negative subjects. CONCLUSIONS: We have shown that a short course of omeprazole will cause a reduction in the plasma vitamin C level of healthy volunteers. This decrease in plasma vitamin C is independent of dietary intake of the vitamin and indicates reduced bioavailability. The clinical significance of this is unclear but any adverse effects will be most apparent in H. pylori infected subjects who have a low pre-treatment vitamin C status.

Ascorbic Acid↗
PubMed2004

Studies of acid exposure immediately above the gastro-oesophageal squamocolumnar junction: evidence of short segment reflux.

BACKGROUND AND AIMS: Oesophageal pH is conventionally recorded from a point 5 cm above the lower oesophageal sphincter. However, the mucosal changes of reflux oesophagitis and intestinal metaplasia tend to affect the segment of oesophagus distal to this and close to the squamocolumnar junction. This study set out to investigate oesophageal acid exposure of squamous mucosa close to the squamocolumnar junction. METHODS: Dual channel 24 hour pH monitoring was carried out in 11 patients with endoscopy negative dyspepsia and no evidence of gastro-oesophageal reflux by conventional oesophageal pH metry. Oesophageal pH was recorded from electrodes positioned 5 mm and 55 mm proximal to the squamocolumnar junction. A novel technique was developed using metal clips to secure the pH catheter to the oesophageal mucosa and maintain these electrode positions. Oesophageal manometry indicated that the distal electrode was within the high pressure zone of the lower oesophageal sphincter. RESULTS: We found that 24 hour oesophageal acid exposure (per cent time pH <4) was greater 5 mm above the squamocolumnar junction compared with the conventional position 5 cm more proximal (11.7% v 1.8%; p<0.001). The greater acid exposure at the distal versus the conventional site was apparent in both the upright (12.7% v 2.3%) and supine (10.5% v 1.3%) positions, as well as during preprandial (14.2% v 1.6%) and postprandial (21.8% v 2.8%) periods (p<0.001 for each). The number of reflux events recorded close to the squamocolumnar junction was also higher than at the conventional position (168 v 33; p<0.001). There was no correlation between acid exposure at the two sites. CONCLUSIONS: The squamous mucosa of the most distal oesophagus is exposed to substantial acidic reflux, even in patients without evidence of conventional reflux disease. This short segment reflux may explain the high incidence of metaplasia and neoplasia at the gastro-oesophageal junction.

Adult↗
PubMed2002

Randomised trial of endoscopy with testing for Helicobacter pylori compared with non-invasive H pylori testing alone in the management of dyspepsia.

OBJECTIVE: To compare the efficacy of non-invasive testing for Helicobacter pylori with that of endoscopy (plus H pylori testing) in the management of patients referred for endoscopic investigation of upper gastrointestinal symptoms. DESIGN: Randomised controlled trial with follow up at 12 months. SETTING: Hospital gastroenterology unit. PARTICIPANTS: 708 patients aged under 55 referred for endoscopic investigation of dyspepsia, randomised to non-invasive breath test for H pylori or endoscopy plus H pylori testing. MAIN OUTCOME MEASURE: Glasgow dyspepsia severity score at one year. Use of medical resources, patient oriented outcomes, and safety were also assessed. RESULTS: In 586 patients followed up at 12 months the mean change in dyspepsia score was 4.8 in the non-invasive H pylori test group and 4.6 in the endoscopy group (95% confidence interval for difference -0.7 to 0.5, P=0.69). Only 8.2% of patients followed up who were randomised to breath test alone were referred for subsequent endoscopy. The use of non-endoscopic resources was similar in the two groups. Reassurance value, concern about missed pathology, overall patient satisfaction, and quality of life were similar in the two groups. The patients found the non-invasive breath test procedure less uncomfortable and distressing than endoscopy with or without sedation. No potentially serious pathology requiring treatment other than eradication of H pylori was missed. CONCLUSION: In this patient group, non-invasive testing for H pylori is as effective and safe as endoscopy and less uncomfortable and distressing for the patient. Non-invasive H pylori testing should be the preferred mode of investigation.

Adolescent↗
PubMed2002

Dietary nitrate generates potentially mutagenic concentrations of nitric oxide at the gastroesophageal junction.

BACKGROUND & AIMS: Twenty-five percent of absorbed dietary nitrate is re-secreted in saliva, and 30% of this is reduced to nitrite by buccal bacteria. When saliva is swallowed, the acidic gastric juice reduces the nitrite to nitric oxide. The aim of this study was to examine the anatomic distribution of nitric oxide generation within the lumen of the upper gastrointestinal tract under basal conditions and after ingesting nitrate equivalent to that in salad portion. METHODS: Using custom-made sensors, the dissolved luminal nitric oxide concentration and pH were measured at 1-cm increments for 2 minutes throughout the length of the stomach and distal esophagus in 15 Helicobacter pylori-negative healthy volunteers with and without ingestion of 2 mmol potassium nitrate. Serum nitrate and saliva nitrite concentrations were also monitored. RESULTS: The nitrate ingestion increased mean (range) serum nitrate from 30 micromol/L (18-49) to 95 micromol/L (32-152), mean salivary nitrite from 36 micromol/L (19-153) to 252 micromol/L (32-600), and mean peak luminal nitric oxide concentration from 4.7 micromol/L (1.4-7.8) to 23.2 micromol/L (2.1-50) (P < 0.05 for each). After nitrate, the peak nitric oxide concentration occurred in 11 of the 15 (73%) subjects within 1 cm distal to the gastroesophageal pH step-up point. The mean nitric oxide concentration over the 1-cm segment immediately distal to the gastroesophageal pH step-up after nitrate was 7.5 micromol/L (range, 0.5-30.7) and was significantly higher than at all other sites. Nitric oxide concentrations greater than 50 micromol/L were observed at the precise location where neutral esophageal pH fell to acidic gastric pH. CONCLUSIONS: Luminal generation of nitric oxide from dietary nitrate via salivary nitrite is maximal at the gastroesophageal junction and cardia. The high concentrations of nitric oxide generated may contribute to the high incidence of mutagenesis and neoplasia at this site.

Adult↗
PubMed2002

Solubility of hypericin in methanol and methanol-pyridine.

The solubility of hypericin in methanol and methanol-pyridine (99:1, v/v) was determined. The addition of pyridine turned out to enhance the solubility of hypericin. In pure methanol only 37.17 micrograms/ml could be dissolved. In comparison, 320.91 micrograms hypericin were soluble in one ml methanol-pyridine (99:1, v/v).

Anthracenes↗
PubMed2001

Haematology and blood chemistry of Cebus apella in relation to sex and age.

An effective health care program entails the prevention, diagnosis and treatment of medical problems. A knowledge of baseline values in clinically normal individuals is essential for determining the limits between good health and disease and for understanding the changes produced by pathogenic agents. However, very little information is currently available concerning the blood chemistry and haematological values of different species of monkeys, particularly new-world primates. The values of some haematological and chemical parameters in Cebus apella were determined. The aim of the present work was to verify the effect of age and sex on normal blood values. Blood samples were collected once a year for two successive years from 36 monkeys living in large captive social groups. Significant differences between males and females were found for AST, GGT, urea nitrogen and creatinine, erythrocytes, haemoglobin and haematocrit. Significant differences between juveniles and adults were found for calcium, AST, alkaline phosphatase, inorganic phosphorus, glucose, neutrophils, lymphocytes and serum protein parameters.

Aging↗
PubMed2001

Unbuffered highly acidic gastric juice exists at the gastroesophageal junction after a meal.

BACKGROUND & AIMS: Gastroesophageal reflux typically occurs after meals. During dual gastric and esophageal pH monitoring, we observed that postprandial refluxate was often more acidic than the gastric contents. This study aimed to investigate this phenomenon. METHODS: Dual gastric and esophageal pH tracings were analyzed from 40 dyspeptic patients. Dual pH electrode pull-through studies were performed in healthy volunteers to document regional variation in intragastric pH under both fasting and postprandial conditions. The squamocolumnar junction was identified using radio-opaque endoscopic clips. We also examined in vitro partitioning of gastric juice added to a homogenized fatty meal. RESULTS: The dual pH traces confirmed that esophageal refluxate was frequently more acidic than the body of the stomach after meals but not during fasting. The pull-through studies showed a pocket of acid at the gastroesophageal junction that escaped the buffering effect of meals, remaining highly acidic (median pH 1.6) compared with the body of the stomach (pH 4.7; P < 0.001). This proximal acid pocket extended from the cardia across the squamocolumnar junction 1.8 cm into the distal esophagus. The in vitro studies showed that acidic gastric juice could partition on top of a homogenized fatty meal. CONCLUSIONS: After eating, highly acidic unbuffered gastric juice is present at the gastroesophageal squamocolumnar junction and is likely to contribute to the high prevalence of disease at this site.

Adult↗
PubMed2001

Absorbance data of hypericin and pseudohypericin used as reference compounds for medicinal plant analysis.

The evaluation of the absorbance data of hypericin and pseudohypericin revealed the molar/specific coefficients of absorbance in methanol-pyridine (99:1, v/v) at the maximum of the longest wavelength to be 51936/1030 and 43486/836, respectively. The absorbance data of hypericin were also determined in methanol. They were not significantly different from those in the presence of pyridine. The decrease of the coefficients by water addition was found to be the same for hypericin and pseudohypericin. It was concluded that hypericin and pseudohypericin reveal the same homoassociation behavior.

Anthracenes↗
PubMed2000

Increased prevalence of precancerous changes in relatives of gastric cancer patients: critical role of H. pylori.

BACKGROUND & AIMS: Helicobacter pylori is believed to predispose to gastric cancer by inducing gastric atrophy and hypochlorhydria. First-degree relatives of patients with gastric cancer have an increased risk of developing gastric cancer. The aim of this study was to determine the prevalence of atrophy and hypochlorhydria and their association with H. pylori infection in first-degree relatives of patients with gastric cancer. METHODS: H. pylori status, gastric secretory function, and gastric histology were studied in 100 first-degree relatives of patients with noncardia gastric cancer and compared with those of controls with no family history of this cancer. RESULTS: Compared with healthy controls, relatives of patients with gastric cancer had a higher prevalence of hypochlorhydria (27% vs. 3%) but a similar prevalence of H. pylori infection (63% vs. 64%). Relatives of cancer patients also had a higher prevalence of atrophy (34%) than patients with nonulcer dyspepsia (5%) matched for H. pylori prevalence. Among the relatives of cancer patients, the prevalence of atrophy and hypochlorhydria was increased only in those with evidence of H. pylori infection, was greater in relatives of patients with familial cancer than in relatives of sporadic cancer index patients, and increased with age. Eradication of H. pylori infection produced resolution of the gastric inflammation in each subject and resolution of hypochlorhydria and atrophy in 50% of the subjects. CONCLUSIONS: Relatives of patients with gastric cancer have an increased prevalence of precancerous gastric abnormalities, but this increase is confined to those with H. pylori infection. Consequently, prophylactic eradication of the infection should be offered to such subjects.

Achlorhydria↗
PubMed2000

Bisanthraquinone glycosides of Hypericum perforatum with binding inhibition to CRH-1 receptors.

Four new bisanthraquinone glycosides, S-(+)-skyrin-6-O-beta-glucopyranoside (1), R-(-)-skyrin-6-O-beta-glucopyranoside (2), S-(+)-skyrin-6-O-beta-xylopyranoside (3) and S-(+)-skyrin-6-O-beta-alpha-arabinofuranoside (4), have been isolated from an ethanol-water (1:1, v/v) dry extract of the aerial parts of Hypericum perforatum L. The structures were elucidated by spectroscopic methods, mainly NMR and mass spectrometry. Circular dichroism was used to determine their axial stereochemistry revealing 1 and 2 to be atropisomers. 1 and 2 inhibited [125I]sauvagine binding to corticotropin releasing hormone (CRH-1) receptors.

Acetylation↗
PubMed2000

Omeprazole, Helicobacter pylori status, and alterations in the intragastric milieu facilitating bacterial N-nitrosation.

BACKGROUND & AIMS: Omeprazole produces greater acid inhibition in Helicobacter pylori-positive than -negative subjects. We investigated whether this is accompanied by more profound changes in the intragastric milieu that facilitates bacterial synthesis of N-nitroso compounds. METHODS: Gastric juice pH; nitrite, ascorbic acid, and total vitamin C concentrations; and colonization by other bacteria were examined before and during omeprazole treatment in subjects with and without H. pylori infection. Studies were performed in the fasting state and after consumption of 2 mmol nitrate (equivalent to a salad meal). RESULTS: Before omeprazole, H. pylori-positive and -negative subjects were similar for all parameters. During omeprazole, H. pylori-positive subjects had a higher intragastric pH (7.8 vs. 3.0; P < 0.00001) and greater colonization with non-H. pylori species (5 x 10(7) vs. 5 x 10(5) CFU/mL; P < 0.05). These bacteria included nitrosating species. During omeprazole treatment, H. pylori-positive subjects had higher intragastric nitrite levels after the nitrate meal (median area under the concentration/time curve, 12,450 vs. 4708 micromol/L. min; P = 0.04). Omeprazole lowered intragastric vitamin C levels in H. pylori-positive but not -negative subjects (1.8 vs. 3.4 microg/mL, respectively; P = 0.02). CONCLUSIONS: In H. pylori-positive subjects, omeprazole produces disturbances in intragastric nitrite, vitamin C, and bacterial colonization that facilitate bacterial N-nitrosation. This may place them at increased risk of mutagenesis and carcinogenesis.

Adult↗
PubMed1999

Novelty in phylogeny of gastrotricha: evidence from 18S rRNA gene.

Gastrotricha form a phylum which is crucial for defining the origin of pseudocoelomates, in that they share a number of characters with Rotifera and Nematoda but also with acoelomates, and even the evolutionary relationships within the phylum are anything but defined. For this reason the first extensive molecular data on Gastrotricha from the 18S rRNA sequences of both orders have been obtained and analyzed. Sequence analyses show that the phylum Gastrotricha is strictly monophyletic along an evolutionary line quite distinct from that of both Rotifera and Nematoda. A new view of the evolutionary history of the phylum Gastrotricha is put forward, in which Chaetonotida, and not Macrodasyida, are the most primitive forms of the group, contrary to the commonly held view. A polyphyletic origin of aschelminthes is supported, and the misleading term pseudocoelomates should be discarded.

Animals↗
PubMed1999

Omeprazole and dietary nitrate independently affect levels of vitamin C and nitrite in gastric juice.

BACKGROUND & AIMS: Hypochlorhydria is associated with an increased risk of gastric cancer. We have studied the effect of pharmacologically induced hypochlorhydria on the gastric juice ascorbate/nitrite ratio, which regulates the synthesis of potentially carcinogenic N-nitroso compounds. METHODS: Saliva, gastric juice, and serum from 20 healthy volunteers (9 positive for Helicobacter pylori), with a mean age of 30 years (range, 20-47 years), were analyzed for nitrite, ascorbic acid, and total vitamin C before and for 2 hours after ingestion of 2 mmol [corrected] nitrate (nitrate content of a standard salad meal). This was repeated after 4 weeks of treatment with omeprazole, 40 mg daily. RESULTS: Before omeprazole treatment, the nitrate meal lowered gastric ascorbic acid levels from 3.8 to 0.9 microg/mL (P < 0.05) and increased median salivary nitrite levels from 44 to 262 micromol/L (P < 0.001); gastric nitrite concentration remained undetected in 10 subjects. Omeprazole increased median fasting gastric nitrite levels from 0 to 13 micromol/L (P = 0.001) and decreased fasting gastric ascorbic acid levels from 3.8 to 0.7 microg/mL (P < 0.001). With omeprazole treatment, gastric nitrite levels after the nitrate meal were markedly increased at 154 micromol/L (range, 49-384 micromol/L; P < 0.001). In H. pylori-infected subjects, omeprazole also decreased total vitamin C levels in both gastric juice and serum. CONCLUSIONS: Omeprazole and dietary nitrate independently decrease the ascorbate/nitrite ratio. This may lead to an increased risk of gastric cancer.

Adult↗
PubMed1998

Symptomatic benefit from eradicating Helicobacter pylori infection in patients with nonulcer dyspepsia.

BACKGROUND: The eradication of Helicobacter pylori infection is beneficial in patients with gastric or duodenal ulcers. The value of eradicating the infection in patients with dyspepsia and no evidence of ulcer disease is not known. METHODS: We performed a randomized, placebo-controlled trial comparing the efficacy of treatment for two weeks with 20 mg of omeprazole orally twice daily, 500 mg of amoxicillin three times daily (with 500 mg of tetracycline three times daily substituted for amoxicillin in patients allergic to penicillin), and 400 mg of metronidazole three times daily (160 patients) with that of omeprazole alone (158 patients) for resolving symptoms of dyspepsia in patients with H. pylori infection but no evidence of ulcer disease on upper gastrointestinal endoscopy. Symptoms were assessed with the Glasgow Dyspepsia Severity Score, with resolution of symptoms defined as a score of 0 or 1 in the preceding six months (maximal score, 20). One year later the patients were assessed to determine the frequency of the resolution of symptoms. RESULTS: One month after the completion of treatment, 132 of 150 patients (88 percent) in the group assigned to received omeprazole and antibiotics had a negative test for H. pylori, as compared with 7 of 152 (5 percent) in the group assigned to receive omeprazole alone. One year later, dyspepsia had resolved in 33 of 154 patients (21 percent) in the group given omeprazole and antibiotics, as compared with 11 of 154 (7 percent) in the group given omeprazole alone (95 percent confidence interval for the difference, 7 to 22 percent; P<0.001). Among the patients in the group given omeprazole and antibiotics, the symptoms resolved in 26 of the 98 patients (27 percent) who had had symptoms for five years or less, as compared with 7 of the 56 patients (12 percent) who had had symptoms for more than five years (P=0.03). CONCLUSIONS: In patients with H. pylori infection and nonulcer, or functional, dyspepsia, treatment with omeprazole and antibiotics to eradicate the infection is more likely to resolve symptoms than treatment with omeprazole alone.

Adolescent↗
PubMed1997

Helicobacter pylori infection and chronic gastric acid hyposecretion.

BACKGROUND & AIMS: We have identified a subgroup of Helicobacter pylori-infected subjects with low or absent gastric acid output. The aim of this study was to document the morphological and functional abnormalities in these subjects and to assess the effect of eradicating the infection. METHODS: The 16 hypochlorhydric subjects (6 men) had a mean age of 55 years (range, 36-79 years). They underwent a 14C-urea breath test, H. pylori serology, fasting gastrin, gastric autoantibodies, gastroscopy with antral and body biopsies, and measurement of peak acid output to pentagastrin (PAO(PG)). Their histology was compared with that of age- and sex-matched duodenal ulcer and nonulcer dyspepsia patients (16 each). H. pylori infection was eradicated in the hypochlorhydric subjects, and the investigations were repeated 6 months later. RESULTS: Compared with controls, the hypochlorhydric subjects had less dense H. pylori colonization, body-predominant colonization and gastritis, and increased prevalence of body atrophy and intestinal metaplasia. Median PAO(PG) before eradication in the hypochlorhydric subjects was 1.1 mmol/h and increased to 12.6 mmol/h after eradication (P < 0.001), with no significant change in body atrophy or intestinal metaplasia. CONCLUSIONS: In some subjects, chronic H. pylori infection produces a body-predominant gastritis and profound suppression of gastric acid secretion that is partially reversible with eradication therapy.

Achlorhydria↗
PubMed1996

The Glasgow Dyspepsia Severity Score--a tool for the global measurement of dyspepsia.

OBJECTIVE: There is currently no reliable tool for providing a global measurement of the severity of dyspepsia in patients with a variety of upper gastrointestinal disorders. We have designed a questionnaire which records frequency of symptoms, effect on routine activities, time off work, frequency of medical consultations, clinical investigations and use of over-the-counter and prescribed medications. The objective of the paper was to assess this questionnaire with respect to reproducibility, validity, responsiveness and performance time. METHODS AND RESULTS: For intra-observer variation, one author interviewed 50 subjects (25 males) including 20 healthy volunteers and 30 with a variety of upper gastrointestinal pathologies. The interview was repeated one week later by the same author who was blinded to the dyspepsia score for the first interview. The second author, who was blinded to the diagnoses and subject identity, scored all the questionnaires. The mean dyspepsia score was 6.78 on Day 1 and was similar at 6.80 on Day 2. The coefficient of variation between Days 1 and 2 was 2%. For inter-observer variation, 30 patients with non-ulcer dyspepsia (NUD) were interviewed by one author and the interview was repeated on a separate occasion within 24 h by a second author who was blinded to the score from the first interview. The mean dyspepsia score for the first author was 10.7 and for the second author 10.9 with a coefficient of variation between the two authors of 8%. Validity was assessed by comparing the dyspepsia scores in healthy volunteers and patients with upper gastrointestinal diseases. The mean score in 80 healthy volunteers was 1.16 (range: 0-7) and was significantly higher in 70 duodenal ulcer (DU) patients (mean score 11.1, range: 6-16) and 80 NUD patients (mean score 10.5, range: 6-17) (P < 0.001 for both vs. healthy volunteers). Responsiveness was assessed by comparing dyspepsia scores before and one year after eradication of Helicobacter pylori infection in 42 DU patients. The mean dyspepsia score before eradication was 11.4 (range: 6-16) and fell to 1.33 (range: 0-11) one year after eradication (P < 0.001). The mean time taken to complete 150 questionnaires was 4 min (range: 3-5.5 min). CONCLUSION: This new questionnaire for assessing the severity of dyspepsia is highly reproducible and has high validity and responsiveness. In addition, it is simple and rapid to perform. It provides a valuable tool for assessing the response to treatment in patients with dyspepsia.

Adolescent↗
PubMed1996

Marked rebound acid hypersecretion after treatment with ranitidine.

OBJECTIVES: Dyspeptic symptoms frequently recur rapidly after withdrawal of H2 antagonists, and this might be related to rebound acid hypersecretion. We have studied this phenomenon in healthy volunteers with and without Helicobacter pylori infection. METHODS: Basal and gastrin-releasing peptide (GRP) (40 pmol/kg/h) stimulated acid output, and gastrin concentration were measured in 18 healthy volunteers (nine were H. pylori positive). Studies were performed before and at 60 h and 10 days after completion of a 60-day course of ranitidine 300 mg nocte. RESULTS: In the H. pylori-negative healthy volunteers, basal acid output increased by a median of 137% 2 days after stopping ranitidine therapy compared with pretreatment values (p = 0.01) and returned to pretreatment values by day 10 posttreatment. Their GRP-stimulated acid output increased by a median of 108% 2 days post ranitidine (p < 0.01) and remained slightly increased at day 10. In H. pylori-positive healthy volunteers, basal acid output increased by a median of 96% 2 days after ranitidine therapy ceased (p < 0.01) and returned to pretreatment values by day 10 posttreatment. Their GRP-stimulated acid output also increased by a median of 56% 2 days posttreatment and returned to pretreatment values by day 10. The increase in acid output both basal and in response to GRP was not accompanied by any rise in gastrin concentration in either the H. pylori-positive or -negative subjects. CONCLUSIONS: Ranitidine therapy is associated with marked rebound hypersecretion of acid, and this may contribute to rapid resurgence of symptoms after therapy has been discontinued.

Anti-Ulcer Agents↗