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Biomedical subjects

D R Morgan

Publications and source records attributed to D R Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1991

Molecular techniques for studying the epidemiology of infection by Helicobacter pylori.

The efficacy of one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of whole-cell protein patterns for fingerprinting isolates of Helicobacter pylori was assessed by means of computerized numerical analysis. Virtually all strains were found to have unique, stable, and reproducible protein profiles. The application of this technique to a collection of isolates from eight patients showed clearly that each harboured a distinct strain that was present before treatment and persisted after treatment. This suggests that relapse was due to recrudescence of the same strain rather than re-infection with a different strain. Minor differences in protein banding profiles within sets of isolates from the same patient were evident, and this was confirmed by means of both two-dimensional PAGE protein patterns and restriction endonuclease analysis of DNA on the same strains.

DNA Fingerprinting↗
PubMed1991

Gastric spiral bacilli in captive cheetahs.

Two kinds of gastric spiral bacilli were identified in the stomachs of captive cheetahs with naturally occurring gastritis. One type was morphologically similar to 'Gastrospirillum hominis'. This organism could not be cultured in vitro. Some of these bacteria had superficial helical filaments, and others did not. The other type was morphologically, biochemically, and bacteriologically similar to Helicobacter pylori. This organism is most likely a new species of Helicobacter. One or both of these bacteria may have been responsible for the gastritis seen in these cheetahs.

Acinonyx↗
PubMed1991

Genomic variation in Helicobacter pylori: application to identification of strains.

DNA digest analysis, ribopatterns, and plasmid profiling were used to determine genomic variation in 55 strains of Helicobacter pylori from patients with gastritis in the USA, Peru, Australia, and the U.K. HaeIII-ribopatterns and total DNA digest patterns showed a high degree of heterogeneity, with at least 33 different genomic types among strains, including some sequential isolates. Plasmids, present in 51% of strains, were less useful as epidemiologic markers. Investigation of 14 multiple isolate sets showed that genotypic variants were present in pre- and post-treatment gastric mucosa, that relapse in some patients was due to reinfection by a genotypically different strain, and that the same strain persisted in most treatment failures. We conclude that molecular methods were excellent for precise identification of H. pylori, but ribopatterns had the advantages of reproducibility, high discrimination, and visual simplicity.

DNA Fingerprinting↗
PubMed1991

Simple noninvasive method to test efficacy of drugs in the eradication of Helicobacter pylori infection: the example of combined bismuth subsalicylate and nitrofurantoin.

Eradication of Helicobacter pylori infections has proved to be difficult. There is a need both for improved therapies and for ways to rapidly identify therapies that show sufficient promise to be worth pursuing. The objectives of this study were to evaluate the value of a therapeutic regimen of a bismuth salt plus nitrofurantoin for eradication of infection by H. pylori and to determine the validity/utility of the urea breath test in monitoring the progress of a clinical trial. We used an 80% eradication rule to define a promising therapeutic regimen, i.e., a regimen that eradicated the infection (no evidence of infection by H. pylori 4 wk after termination of therapy) in at least 80% of the individuals treated. Eighteen men (median age 38) with documented infection by H. pylori completed the study. At the end-of-study evaluation, H. pylori infection was eradicated (negative urea breath test, culture, and histology) in only one of 18 (5.5%) subjects; 15 were positive by the urea breath test, 16 by culture, 15 by Warthin-Starry stain, and 16 by the presence of acute-on-chronic inflammation. Using the 80% eradication rule, any one of these tests alone would have identified that the combination of antimicrobials tested was not effective in the eradication of the infection. We conclude that the urea breath test is a simple, noninvasive, cost-effective method to separate promising from unpromising candidate therapies and for the evaluation of new therapeutic concepts.

Adult↗
PubMed1990

Decontamination of instruments and control of cross infection in general practice.

OBJECTIVE: To assess the effectiveness of decontamination procedures in general practice. DESIGN: Anonymous postal questionnaire survey of 600 general practitioners randomly selected from the national register. SETTING: General practices throughout the United Kingdom. SUBJECTS: 382 General practitioners, a response rate of 65%. RESULTS: 186 General practitioners had autoclaves but 125 used hot water disinfectors or chemical disinfectants to reprocess instruments. 22% (474/2132) Of high risk instruments were inadequately decontaminated. Decontamination was performed by the practice nurse or receptionist in 306 practices. Knowledge of treatment of spillages of blood fluids was uncertain, and only 114 general practitioners used effective methods for dealing with spillages. CONCLUSIONS: A comprehensive central code of practice for control of infection is needed for primary health care staff.

Cross Infection↗
PubMed1990

Evaluation of a selective enrichment technique for the isolation of Campylobacter pylori.

To cultivate Campylobacter pylori from contaminated biopsy specimens, Brucella broth was supplemented with 10% fetal calf serum, 1% Vitox, 1000 units/ml polymyxin B sulfate, 10 micrograms/ml vancomycin, and 2 micrograms/ml amphotericin B. Pseudomonas aeruginosa, Candida albicans, and Enterococcus fecalis were cocultivated with C. pylori. All four strains of C. pylori were recoverable at 24 h. When 21 C. pylori strains were studied in pure culture, 86% grew in the selective enrichment medium. In a clinical study, the selective enrichment technique resulted in isolation of C. pylori from 50% of patient samples, compared with isolation from only 36% of samples with agar cultivation. The selective enrichment technique may be more sensitive than techniques currently employed to isolate C. pylori from gastric tissue.

Bacteriological Techniques↗
PubMed1990

Persistence of Helicobacter pylori in conventionalized piglets.

Gnotobiotic piglets were challenged at 3 days of age with Helicobacter (Campylobacter) pylori and then transferred to conventional housing at 24 days of age. Piglets were sacrificed 43-45, 57-60, and 87-90 days after challenge. H. pylori was recovered from the stomachs of all piglets challenged except for two piglets sacrificed 45 days after challenge. H. pylori was not recovered from uninfected control piglets. In addition to H. pylori, Lactobacillus and Bacillus species were recovered from conventionalized piglets. Serum from infected piglets contained H. pylori-specific IgG, IgM, and IgA. IgM titers peaked at 14 days after challenge and then declined. IgG and IgA titers continued to rise over the course of the experiment. Piglets in both uninfected control and challenged groups demonstrated lymphofollicular gastritis, but the gastritis was more severe in challenged piglets.

Animals↗
PubMed1990

Helicobacter pylori gastric infection in gnotobiotic beagle dogs.

Establishment of infection with Helicobacter pylori and gastritis in nonhuman species is currently only successful in gnotobiotic piglets. This study was designed to determine whether H. pylori will colonize the gastrointestinal tract of gnotobiotic dogs. Gnotobiotic beagle pups were derived by standard methods. Group A (five dogs) was orally challenged with 3 x 10(8) H. pylori at 7 days of age. Group B (two dogs) received only peptone water but was contact-exposed beginning on day 23 postinfection (p.i.). Necropsy was performed on dogs on day 30 p.i. H. pylori colonized the stomach of all dogs (groups A and B). Urease map analysis correlated with the microbiologic findings and indicated that the density of colonization was less than that observed in human tissue. Organisms were also recovered from the pharynx, esophagus, duodenum, and rectum of 1, 2, 2, and 1 dog, respectively. All group A and one group B dog developed serum immunoglobulin G specific for H. pylori by day 30 p.i. Gross lesions were restricted to the stomach and consisted of small (less than 1 mm) lymphoid follicles. Microscopically, there were focal to diffuse lymphoplasmacytic infiltrates with follicle formation and mild to moderate infiltration of neutrophils and eosinophils in the gastric lamina propria. With the Warthin-Starry silver stain, organisms were seen on the surface of the gastric epithelial cells, beneath the mucus layer. We conclude that H. pylori colonizes the stomachs of gnotobiotic dogs for at least 1 month and the lesions resemble those seen in humans. H. pylori is transmissible by contact from infected to noninfected dogs.

Animals↗
PubMed1990

Antibody to cytotoxin in infection by Helicobacter pylori.

Gastrointestinal disease and colonization by Helicobacter pylori were determined in 36 asymptomatic volunteers and 30 symptomatic individuals undergoing endoscopy and biopsy. Serum antibody immunoglobulin G (IgG) and IgA to H. pylori were measured by enzyme-linked immunosorbent assay. Serum antibody to a cytotoxin produced by H. pylori was detected with a neutralization assay. Serum IgG was 95% predictive of infection by H. pylori, and serum IgA was 88% predictive. Antibody to the cytotoxin was detected in 12 of 18 infected individuals. Antibody to the cytotoxin was a highly specific (96%), but not a very sensitive (67%), indicator of infection by H. pylori. The neutralization assay was 87% predictive of infection. These data confirm the diagnostic value of serum antibody to H. pylori for the detection of infection. The toxin-neutralizing activity of sera from individuals infected with H. pylori suggests that the cytotoxin is produced in vivo. It may therefore contribute to disease associated with H. pylori.

Adult↗
PubMed1990

Signature patterns of DNA restriction fragments of Helicobacter pylori before and after treatment.

The genomic DNA of Helicobacter pylori was studied by electrophoretic analysis of restriction endonuclease fragments. Twenty seven isolates from eight patients in the United Kingdom, obtained before and after treatment with nitrofurantoin, and two reference strains from Australia and Peru were investigated. Digestion of DNA with HaeIII, which gave the clearest band pattern of the 20 enzymes tested, showed that each set of isolates from a single patient had a unique band pattern. The DNA signature band patterns of strains from different patients were less than or equal to 62% similar (average 43%); similarities of patterns from the same patient were generally greater than or equal to 86%. Some minor but reproducible polymorphisms (less than or equal to five bands) in the signature region were detected in most consecutive isolates. Plasmid DNA was detected in isolates from five patients, but major pattern differences were attributed to genomic variation. It is concluded that the HaeIII DNA digest signature fingerprints provide a reproducible and sensitive method of discriminating between isolates of H pylori.

Campylobacter↗
PubMed1989

Strain variation in Campylobacter pylori detected by numerical analysis of one-dimensional electrophoretic protein patterns.

A total of 21 clinical isolates of Campylobacter pylori from Peru and the United Kingdom and two reference strains (from Australia), including the type strain (NCTC 11637T), were characterized by high resolution one-dimensional SDS-polyacrylamide gel electrophoresis of cellular proteins. The protein patterns contained more than 40 discrete bands and the approximate molecular weights of the major bands were 22, 27, 46, 57, 60, 65 and 93 kD. The total patterns were used as the basis of numerical analysis. Most strains were clustered in four phenons at 91% similarity with the exception of six ungrouped strains. Overall similarity was high with all strains linked in the phenogram at greater than or equal to 81%. Variation among strains was attributable principally to qualitative and quantitative band differences in the 47 to 56 kD (hypervariable) region of the C. pylori protein profile. From the analysis, ten different electropherotypes (EP-types) were identified. We demonstrated that differences were detectable among isolates from widely separated geographical locations as well as from the same location, although multiple isolates from two Peruvian patients had the same electropherotype. Our results indicate that determination of protein profiles provides the basis of a reproducible method for characterization of C. pylori isolates.

Bacterial Proteins↗
PubMed1989

Campylobacter pylori virulence factors in gnotobiotic piglets.

Thirty-three gnotobiotic piglets from four litters were challenged with motile and nonmotile strains of Campylobacter pylori. The most motile strain, 26695, was the most virulent, with a 100% infection rate. The least motile strain, Tx30a, was the least virulent, with an infection rate of only 17%. Strain 60190 was weakly motile and had intermediate virulence, with an infection rate of 40%. Strains recovered from piglets were more motile than the challenge strains. The challenge strains also differed in cytotoxin production. The least virulent strain, Tx30a, was nontoxigenic, while the other two strains produced high levels of cytotoxin. Thus, virulence of C. pylori for gnotobiotic piglets correlated very well with motility and not as well with cytotoxin production.

Animals↗
PubMed1989

Angiofollicular lymph node hyperplasia with amyloidosis.

Two cases of angiofollicular lymph node hyperplasia are described, one of the solitary plasma cell type the other of the multicentric hyaline vascular type. Both cases illustrate the wide ranging clinical and pathological findings associated with this condition but both also have unusual features. The solitary plasma cell lesion had an exceptional 32 year clinical history and was associated with systemic amyloidosis of AL type. The multicentric hyaline vascular case was associated with coexistent multiple myeloma and amyloid deposition also of AL type. These cases are presented with a review of the relevant literature.

Amyloidosis↗
PubMed1988

Needlestick injuries: how can we teach people better about risk assessment?

At work people run some small risk of death or injury which is directly attributable to their occupation. In biomedical sciences the accidental puncture of the skin by hypodermic needles, other instruments or broken glass has long been regarded as an occupational hazard and there is increasing concern that staff could become infected with a range of micro-organisms, including hepatitis B and the Human Immunodeficiency Virus (HIV). Needlestick injuries should be preventable if staff are trained effectively and take care about disposal of used syringes and needles. Staff at risk must be offered pre-exposure vaccination for hepatitis B and resources must be provided for special training. Fundamental changes may be required in methods and equipment and a number of new ways of targeting groups of health care staff with information are discussed.

Accidents, Occupational↗
PubMed1988

Cytotoxic activity in broth-culture filtrates of Campylobacter pylori.

Broth-culture filtrates of Campylobacter pylori induced non-lethal cytopathic effects in vitro in 7 of 9 mammalian cell lines tested. Transmission electronmicroscopy revealed that the response consisted of intracellular vacuolisation. Intestine 407 cells were among the most responsive and were used for routine assay. About 55% of isolates of C. pylori tested, originating from four geographic regions worldwide, produced cytotoxic activity. The activity was neutralisable by specific antisera to broth-culture filtrates or to sonicated bacteria but not by antisera to other bacterial preparations. Cytotoxic activity was heat-labile (70 degrees C for 30 min), was protease-sensitive and ammonium-sulphate precipitable. It did not pass through an ultrafiltration membrane with a nominal mol.-wt limit of 100 X 10(3). It was concluded that C. pylori can produce a factor that alters cultured cells in vitro. The relevance of this factor to the pathogenesis of gastritis associated with C. pylori remains to be determined.

Animals↗