The significance of cagA and vacA subtypes of Helicobacter pylori in the pathogenesis of inflammation and peptic ulceration.
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AIMS: To assess the significance of cagA and vacA subtypes of Helicobacter pylori in relation to inflammation and density of bacterial colonisation in vivo within a dyspeptic UK population. METHODS: Dyspeptic patients who were Helicobacter pylori positive had antral samples taken for histology and culture. Gastroduodenal pathology was noted. The grade of bacterial density and inflammation was assessed using the Sydney system. Bacterial DNA was extracted and the vacA alleles and the cagA/gene typed using PCR. RESULTS: 120 patients were studied. There was high rate of cagA positive strains in this population. Bacterial density did not correlate with the presence of peptic ulceration. There was a significant association between cagA positive strains and increased inflammation and bacterial density. The vacA s1 type independently correlated with extensive chronic inflammation but there was no association with bacterial density. The vacA m type did not correlate with extent of inflammation or bacterial density. CONCLUSIONS: The results suggest that cagA is important in the pathogenesis of inflammation and peptic ulceration. These findings are in keeping with the hypothesis that cagA acts as a marker for a cag pathogenicity island which encodes several genes involved in inflammation. The vacA s1 allele correlates with inflammation independently of cagA, possibly through its enhanced ability to produce the vacuolating cytotoxin. (+info)
Chemokine mRNA expression in gastric mucosa is associated with Helicobacter pylori cagA positivity and severity of gastritis.
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AIM: To investigate the association between the quantity of gastric chemokine mRNA expression, severity of gastritis, and cagA positivity in Helicobacter pylori associated gastritis. METHODS: In 83 dyspeptic patients, antral and corpus biopsies were taken for semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and histological grading of gastritis. Gastritis was evaluated by visual analogue scales. Quantities of chemokine (IL-8, GRO alpha, ENA-78, RANTES, MCP-1) RT-PCR products were compared with G3PDH products. Each sample was also evaluated for the presence of cagA and ureA mRNA by RT-PCR. RESULTS: mRNA expression of all five chemokines was significantly greater in H pylori positive than in H pylori negative mucosa. In H pylori positive patients, in the antrum C-X-C chemokine mRNA expression was significantly greater in cagA positive patients than in cagA negative patients, but there were no significant differences in C-C chemokine mRNA expression. In H pylori positive patients, chemokine mRNA expression in the corpus was less than in the antrum. In contrast to the antrum, only GRO alpha mRNA expression was significantly greater in cagA positive infection. Polymorphonuclear cell infiltration was correlated with C-X-C chemokine mRNA expression. Significant correlations were also found between bacterial density and C-X-C chemokine mRNA expression. CONCLUSIONS: In H pylori infection, C-X-C chemokines may play a primary role in active gastritis. Infection with cagA positive H pylori induces greater gastric chemokine mRNA expression in the antral mucosa, which may be relevant to the increased mucosal damage associated with cagA positive H pylori infection. (+info)
Influences of Helicobacter pylori on serum pepsinogen concentrations in dialysis patients.
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BACKGROUND: Patients with impaired renal function have been known to have elevated concentrations of serum pepsinogens, which are raised by Helicobacter pylori infection of the stomach. The present study was performed to examine the effect of H. pylori infection on serum pepsinogen concentrations in dialysis patients. METHODS: Forty nine patients on dialysis and 48 subjects with no known kidney disease were examined for upper gastroduodenal endoscopy, H. pylori infection and serum concentrations of pepsinogen I and II. The status of H. pylori infection was evaluated from results of a urease test, histology and culture of biopsy specimens of the gastric mucosa. Serum pepsinogen levels were measured by radioimmunoassay. RESULTS: Serum concentrations of pepsinogen I and II were elevated in the dialysis patients in comparison with those in the controls (277.4+/-24.2 vs 52.6+/-4.0 pg/ml, P<0.01 for pepsinogen I, and 30.2+/-2.9 vs 14.9+/-1.3 pg/ml, P<0.01 for pepsinogen II). In both the dialysis patients and controls, those with H. pylori infection had significantly higher concentrations of serum pepsinogen I and II and a lower ratio of pepsinogen I to pepsinogen II than those without infection. Among the controls, 15 of 25 subjects with atrophic gastritis had a pepsinogen I/pepsinogen II ratio < or = 3.0, while only two out of 17 patients on dialysis fell into this range. CONCLUSIONS: We conclude that H. pylori status should be taken into account when serum pepsinogen concentrations are evaluated in dialysis patients. (+info)
Phycomycotic gastritis in buffalo calves (Bubalis bubalis).
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Mycotic gastritis, primarily caused by Rhizopus sp. was seen in six buffalo calves (7-13 days old) at postmortem examination. The predominant lesions were numerous raised ulcers in which were hyphae of Rhizopus. In three calves, Candida organisms were also present superficially in the ulcers. Other changes in the mucosa were severe congestion, haemorrhage, thrombosis, necrosis, and infiltration by lymphocytes and neutrophils. Both Rhizopus and Candida were highly pathogenic to rabbits when inoculated intravenously. The disease could not be reproduced experimentally by feeding of Rhizopus orally to rabbits and calves. (+info)
Quantitative assessment of gastric atrophy using the syntactic structure analysis.
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AIM: To assess the topographical relation between gastric glands, using the minimum spanning tree (MST), to derive both a model of neighbourhood and quantitative representation of the tissue's architecture, to assess the characteristic features of gastric atrophy, and to assess the grades of gastric atrophy. METHODS: Haematoxylin and eosin stained sections from corporal and antral biopsy specimens (n = 139) from normal patients and from patients with nonatrophic gastritis and atrophic gastritis of grades 1, 2, and 3 (Sydney system) were assessed by image analysis system (Prodit 5.2) and 11 syntactic structure features were derived. These included both line and connectivity features. RESULTS: Syntactic structure analysis was correlated with the semiquantitative grading system of gastric atrophy. The study showed significant reductions in the number of points and the length of MST in both body and antrum. The standard deviation of the length of MST was significantly increased in all grades of atrophy. The connectivity to two glands was the highest and most affected by the increased grade of atrophy. The reciprocal values of the Wiener, Randic, and Balaban indices showed significant changes in the volume of gland, abnormality in the shape of glands, and changes in irregularity and branching of the glands in both types of gastric mucosa. There was a complete separation in the MST, connectivity, and index values between low grade and high grade gastric atrophy. CONCLUSIONS: (1) Gastric atrophy was characterised by loss of the gland, variation in the volume, reduction in the neighbourhood, irregularity in spacing, and abnormality in the shape of the glands. (2) Syntactic structure analysis significantly differentiated minor changes in gastric gland (low grade atrophy) from high grade atrophy of clinical significance. (3) Syntactic structure analysis is a simple, fast, and highly reproducible technique and appears a promising method for quantitative assessment of atrophy. (+info)
Characterization of a culturable "Gastrospirillum hominis" (Helicobacter heilmannii) strain isolated from human gastric mucosa.
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Spiral organisms were isolated from an antral gastric mucosal biopsy specimen from a dyspeptic patient with gastritis. Only corkscrew-shaped organisms resembling "Gastrospirillum hominis" ("Helicobacter heilmannii") but no Helicobacter pylori-like organisms were seen in histological sections. H. pylori was not cultured from specimens from this patient. On the basis of biochemical reactions, morphology, ultrastructure, and 16S DNA sequencing, the isolated "G. hominis" was shown to be a true Helicobacter sp. very similar to Helicobacter felis and the "Gastrospirillum" but was separate from H. pylori. "G. hominis" is a pleomorphic gram-negative cork-screw-shaped, motile rod with 3 to 8 coils and a wavelength of about 1 micrometer. In contrast to H. pylori, it has up to 14 sheathed flagellar uni- or bipolar fibrils but no periplasmic fibrils. "G. hominis" grows under microaerobic conditions at 36 and 41 degrees C on 7% lysed, defibrinated horse blood agar plates within 3 to 7 days and can be subcultured under microaerobic but not under anaerobic conditions on media similar to those used for H. pylori and H. felis. The small translucent colonies were, in contrast to those of H. felis, indistinguishable from those of H. pylori. "G. hominis" is, like H. pylori and H. felis, motile, is oxidase, catalase, nitrite, nitrate, and urease positive, and produces alkaline phosphatase and arginine arylamidase. Like H. pylori and H. felis, it is sensitive to cephalothin (30-microgram disc), resistant to nalidixic acid (30-microgram disc), and sensitive to most other antibiotics. The 16S DNA sequence clusters "G. hominis" together with "Gastrospirillum," H. felis, Helicobacter bizzozeronii, Helicobacter salmonii, Helicobacter nemestrinae, Helicobacter acinonychis, and H. pylori. (+info)
Allelic diversity of the Helicobacter pylori vacuolating cytotoxin gene in South Africa: rarity of the vacA s1a genotype and natural occurrence of an s2/m1 allele.
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We describe the rarity of Helicobacter pylori strains of vacuolating cytotoxin type s1a (the type most commonly associated with peptic ulceration in the United States) among black and mixed-race South Africans. We also provide the first description of a naturally occurring strain with the vacA allelic structure s2/m1. (+info)
Helicobacter pylori-induced chronic active gastritis, intestinal metaplasia, and gastric ulcer in Mongolian gerbils.
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The establishment of persisting Helicobacter pylori infection in laboratory animals has been difficult, but in 1996 Hirayama reported the development of a successful Mongolian gerbil model. The present study was undertaken with two aims: to better characterize the normal histological structure and histochemical properties of the gastric mucosa of the Mongolian gerbil; and to evaluate the progression of the histopathological features of H. pylori-induced gastritis in this animal model for one year after the experimental infection. Seventy-five Mongolian gerbils were used. Mongolian gerbils were sacrificed at 2, 4, 8, 12, 26, 38, and 52 weeks after H. pylori inoculation. Sections prepared from stomachs immediately fixed in Carnoy's solution were stained with hematoxylin and eosin and Alcian blue at pH 2.5/periodic acid-Schiff, a dual staining consisting of the galactose oxidase-cold thionin Schiff reaction and paradoxical Concanavalin A staining, and with immunostaining for H. pylori and BrdU. H. pylori infection induced in the Mongolian gerbil a chronic active gastritis, in which a marked mucosal infiltration of neutrophils on a background of chronic inflammation became detectable 4 weeks after inoculation and continued up to 52 weeks. Intestinal metaplasia and gastric ulcers appeared after 26 weeks in some of the animals, whereas others developed multiple hyperplastic polyps. The Mongolian gerbil represents a novel and useful model for the study of H. pylori-induced chronic active gastritis and may lend itself to the investigation of the epithelial alterations that lead to intestinal metaplasia and gastric neoplasia. (+info)