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L Engstrand

Publications and source records attributed to L Engstrand.

102 records · Page 6Linked to original sources
PubMed1992

Urease-associated heat shock protein of Helicobacter pylori.

Helicobacter pylori urease is an extracellular, cell-bound enzyme with a molecular weight of approximately 600,000 (600K enzyme) comprising six 66K and six 31K subunits. A 62K protein is closely associated with the H. pylori urease, both in crude preparations and after gel filtration; this protein can be removed from the urease by ion-exchange chromatography without inactivating the enzyme. We purified this urease-associated protein and determined its N-terminal amino acid sequence. The sequence is 80% homologous (identical plus conserved amino acid residues) to the Escherichia coli GroEL heat shock protein (HSP), 75% homologous to the human homolog, and 84% homologous to the HSP homolog found in species of Chlamydia. Thus, the 62K urease-associated protein of H. pylori belongs to the HSP60 family of stress proteins known as chaperonins. Evidently this protein, HSP62, participates in the extracellular assembly and/or protection of the urease against inactivation in the hostile environment of the stomach.

Amino Acid Sequence↗
PubMed1992

Reverse transcription and polymerase chain reaction amplification of rRNA for detection of Helicobacter species.

Sequence data on Helicobacter pylori 16S rRNA were used to select two 22-base oligonucleotide primers for use in a polymerase chain reaction (PCR) for detection of H. pylori. H. pylori cells were treated with lysis buffer, boiled, and chloroform extracted. Reverse transcription of rRNA was followed by PCR amplification (RT-PCR) of the synthesized cDNA and 16S rRNA gene. The amplified PCR products were analyzed by agarose gel electrophoresis and Southern blotting. Using ethidium bromide-stained agarose gels, we were able to detect the expected 500-bp DNA fragment from as few as two H. pylori organisms per reaction. The specificity of the RT-PCR assay was tested with 27 clinical isolates and related reference strains; although the number of bacterial cells used per reaction was 10(5)-fold greater than the number of H. pylori organisms used, amplification was detected only with bacteria in the same genus, H. cinaedi and H. mustelae. Ten H. pylori organisms per biopsy specimen were detected on agarose gels when organisms were added to samples prepared from a processed colon biopsy sample. RT-PCR results were consistent with urea breath test and culture results in 14 of 15 gastric biopsy specimens; the specificity was 100%. RT-PCR of rRNA from H. pylori increased the sensitivity of pathogen detection at least 25- to 50-fold compared with that of previous PCR assays. This low level of detection by RT-PCR assay may prove to be well suited for verifying eradication following therapy.

Base Sequence↗
PubMed1991

Gastric epithelial cells in Helicobacter pylori-associated gastritis express HLA-DR but not ICAM-1.

Induced expression of the intercellular adhesion molecule 1 (ICAM-1) and of the major histocompatibility complex (MHC) class II antigens has been simultaneously observed on keratinocytes and epithelial cells in the thyroid and kidney, suggesting that ICAM-1 and HLA-DR expression might be under common regulation. We have previously found an association between the presence of Helicobacter pylori and an induced expression of class II antigens on gastric epithelial cells in gastric biopsy specimens from patients with gastritis. In this study we investigated whether ICAM-1 could also be expressed on the gastric epithelium. Thirty-one patients with clinical indications for upper gastrointestinal endoscopy were examined. In 23 patients gastritis was diagnosed endoscopically and histologically and H. pylori was cultured from biopsy specimens. In eight patients neither histological gastritis nor growth of the bacteria was observed. Immunoperoxidase staining demonstrated expression of HLA-DR but not ICAM-1 on the gastric epithelial cells in all patients with H. pylori-associated gastritis, indicating regulatory mechanisms different from those of other epithelial cells.

Adult↗
PubMed1991

An increased number of gamma/delta T-cells and gastric epithelial cell expression of the groEL stress-protein homologue in Helicobacter pylori-associated chronic gastritis of the antrum.

Numerous studies have shown that the presence of Helicobacter pylori in the stomach is linked to the development of chronic gastritis most commonly seen in the antrum. However, the pathogenic mechanisms are unclear. In 23 of 31 patients, examined due to symptoms from the upper gastrointestinal tract, H. pylori-associated chronic gastritis of the antrum was diagnosed histologically and by growth of H. pylori. Immunoperoxidase staining on gastric biopsy specimens from these patients showed an increased number of gamma/delta T-cells within the epithelium. Furthermore, the Mab ML30 (raised against the 65 kDa heat shock protein of mycobacteria) demonstrated positive staining in the gastric epithelial cells in all H. pylori-positive but not in H. pylori-negative biopsy specimens. H. pylori also reacted with ML30, as detected by immunoperoxidase staining as well as by immunoblotting. Intraepithelial gamma/delta T cells may play a role in host defense against invading H. pylori, and the bacteria may trigger an autoimmune response to stress proteins expressed by the gastric epithelial cells.

Adult↗
PubMed1990

Inoculation of barrier-born pigs with Helicobacter pylori: a useful animal model for gastritis type B.

At the age of 8 weeks, 15 barrier-born pigs, specific pathogen free, were inoculated intragastrically with suspensions of 10(7) to 10(10) CFU of Helicobacter pylori after pretreatment with omeprazole. The pigs were observed for up to 12 weeks, endoscopic biopsy specimens were taken, and serum samples were drawn. H. pylori was identified by routine culturing and by staining with an H. pylori-specific monoclonal antibody on cryostat sections of gastric biopsy specimens. In 11 of 15 inoculated pigs, H. pylori was detected throughout the observation period. In these infected pigs, there was an antibody response to H. pylori, as determined in serum by an enzyme immunoassay. Furthermore, the development of superficial, focal gastritis with infiltrates of mononuclear class II antigen-expressing lymphocytes was observed immunohistologically. H. pylori was never detected and an antibody response to H. pylori was not observed in two control pigs. The development of gastritis and the systemic antibody response to H. pylori support the usefulness of this animal model for studies of H. pylori-related human diseases.

Animals↗
PubMed1989

Association of Campylobacter pylori with induced expression of class II transplantation antigens on gastric epithelial cells.

Campylobacter pylori was identified with immunoperoxidase staining and a mouse monoclonal antibody directed against C. pylori in gastric biopsy specimens from 24 patients with gastritis. C. pylori was not found in gastric biopsy specimens from six subjects with histologically normal mucosa. The monoclonal antibody, which was reactive with a surface protein of approximately 20 kilodaltons, was found to be specific for C. pylori, and the immunoperoxidase staining proved to be more sensitive and rapid than culture in detecting the organism. In the tissue specimens where C. pylori was detected with the monoclonal antibody, there was a strong expression of class II transplantation antigens on the epithelial cells and an increased number of T lymphocytes. These findings indicate that C. pylori may initiate local immune responses.

Antibodies, Monoclonal↗