PubMed Health⌕ Search

Biomedical subjects

Barry J Marshall

Publications and source records attributed to Barry J Marshall.

9 recordsLinked to original sources
PubMed2025

Advances in Helicobacter pylori lipopolysaccharide structure and function.

Helicobacter pylori is a widespread pathogen responsible for chronic gastritis, peptic ulcers, and an elevated risk of gastric cancer. Lipopolysaccharide (LPS), localized exclusively in the outer leaflet of the outer membrane, is essential for maintaining bacterial integrity. Recent advances have deepened our understanding of H. pylori LPS structure, particularly lipid A modifications and the redefinition of the core oligosaccharide and O-antigen regions. The complete set of enzymes involved in LPS biosynthesis has been identified in the reference strain G27, and comparative genomics has revealed a notable regional difference (the absence of the heptan domain in East Asian strains). Here, we summarize recent insights into the structure and function of H. pylori LPS, emphasizing its role in bacterial persistence and its promise as a target for LPS-based glycoconjugate vaccine development.

Helicobacter pylori↗
PubMed2005

Prevalence of Helicobacter pylori in Indigenous Western Australians: comparison between urban and remote rural populations.

OBJECTIVES: To determine and compare the prevalence of Helicobacter pylori in an urban and a remote rural Western Australian Indigenous community. DESIGN: Cross-sectional study of Helicobacter pylori status determined by urea breath tests between mid-January 2003 and the end of June 2004. PARTICIPANTS: 520 self-selected fasting participants, comprising 270 members of the Martu community at Jigalong, Punmu and Parnngurr in the East Pilbara region (129 men, 141 women; age range, 2-90 years) and 250 people from the Perth Indigenous community (96 men, 154 women; age range, 3-75 years. RESULTS: The overall prevalence of H. pylori was 76%, but the prevalence in the remote rural community was 91%, compared with 60% in the urban community. The odds of having H. pylori were six times greater for rural than for urban participants (odds ratio [OR], 6.34; 95% CI, 3.89-10.33). Further, the overall odds of H. pylori infection in males (rural and urban combined) were greater than for females (OR, 1.61; 95% CI, 1.02-2.54). In both communities, the prevalence of infection remained relatively constant after the age of 10. CONCLUSIONS: The prevalence of H. pylori in the two Indigenous communities was two to three times higher than that in the non-Indigenous Australian population and higher than that shown in previous studies in Indigenous Australians.

Adolescent↗
PubMed2005

The relation of Helicobacter pylori to gastric adenocarcinoma and lymphoma: pathophysiology, epidemiology, screening, clinical presentation, treatment, and prevention.

Helicobacter pylori infection may be the most common chronic bacterial infection worldwide; however, the prevalence varies between countries and is usually linked to socioeconomic conditions. Gastric cancer is one of the most frequent cancers in developing countries and usually about the seventh most common in developed countries. This article explores the relation of H. pylori to gastric adenocarcinoma and lymphoma. The pathophysiology, epidemiology, screening, clinical presentation, treatment, and prevention are discussed.

Adenocarcinoma↗
PubMed2005

Identifying cloned Helicobacter pylori promoters by primer extension using a FAM-labelled primer and GeneScan analysis.

The transcriptional start sites of 27 promoters in Helicobacter pylori strain 4187E have been successfully identified using a non-radioactive primer extension protocol. The technique involves reverse transcribing mRNA with a sequence-specific FAM-labelled primer. The length of the FAM-labelled cDNA primer extension product can be analysed on a standard DNA sequencer using GeneScan software. This information can be used in conjunction with DNA sequencing data to identify the transcriptional start site of a promoter. Total bacterial RNA produced more specific primer extension products with stronger FAM signals than a population enriched for mRNA. Using this technology, it is not necessary to complete the DNA sequencing reactions in parallel with the primer extension experiments. The FAM-labelled primer extension products do not require a PCR amplification step prior to analysis on a sequencing gel, and no phenol/chloroform purifications are required at any stage of the procedure. Fluorescent-based primer extension methods have obvious advantages over the conventional radioactive protocols, and this report extends the currently used methodologies in this field.

Base Sequence↗
PubMed2005

Methodology and transport medium for collection of Helicobacter pylori on a string test in remote locations.

BACKGROUND: Helicobacter pylori can be isolated from patients using the string test but contaminating oral and nasopharyngeal microflora need to be suppressed by rapid plating out onto selective culture media. Recently, use of this diagnostic method was enhanced by using a novel transport medium to collect specimens from subjects in a remote Australian clinic over 1300 km from the laboratory. METHODS: Retrieved string tests were transported to the laboratory in chilled polystyrene boxes in 5 ml screw-cap bottles with 3 ml of a brain heart infusion broth plus antibiotics. These were 20 g/ml vancomycin, 10 g/ml trimethoprim, 10 g/ml cefsulodin, and 10 g/ml amphotericin B. A comparison was made between subjects who gargled with a chlorhexidine mouthwash before swallowing the string test and those who did not. RESULTS: Forty-five urea breath test-positive subjects were tested and H. pylori was isolated from 34 of them. Successful culture was achieved from string tests that were in transit for up to 29 hours and where the maximum temperature in the transport box was 14 degrees C. The additional use of a mouthwash had a marked effect on the isolation rate. H. pylori was cultured from 75% of subjects who gargled but only from 39% who did not. CONCLUSIONS: This methodology and transport medium can broaden the use of the string test to more remote geographic areas where endoscopy is not feasible so that H. pylori isolates may still be obtained for diagnostic and epidemiologic studies. The value of this promising methodology of collection and transport should be assessed in a controlled study.

Adolescent↗
PubMed2003

Nitazoxanide in treatment of Helicobacter pylori: a clinical and in vitro study.

Nitazoxanide (NTZ) is an antibiotic with microbiological characteristics similar to those of metronidazole but without an apparent problem of resistance. The aim of this study was the prospective evaluation of NTZ given as a single agent in the treatment of Helicobacter pylori infection. Twenty culture-positive patients with dyspepsia who had previously failed at least one course of H. pylori eradication therapy were enrolled. Subjects received 1 g of NTZ twice daily for 10 days. The safety and tolerability of the drug were assessed by physical examination, monitoring of adverse events, and clinical laboratory evaluation. Urea breath tests (UBTs) were performed 6 weeks posttreatment. H. pylori was isolated from UBT-positive patients by the string test or endoscopy with biopsy, and the MICs for these isolates were compared to those for isolates obtained pretherapy. The levels of tizoxanide, the active deacylated derivative of NTZ, were measured in blood, saliva, and tissue from two patients during treatment. The UBT results were positive for all 20 patients after completion of NTZ therapy. The MIC results demonstrated that the NTZ susceptibilities of none of the strains isolated from the patients posttherapy had changed significantly. No major adverse reactions were observed, but frequent minor side effects were observed. In conclusion, NTZ did not eradicate H. pylori when it was given as a single agent.

Adult↗
PubMed2002

Evaluation of a new formulation CLOtest.

BACKGROUND AND AIMS: The CLOtest and other rapid urease detection kits are widely used in the endoscopic diagnosis of Helicobacter pylori. A new formulation CLOtest has been developed with the goal of obtaining a positive result more rapidly. The aims of this study were to validate the sensitivity and specificity of the new test and compare the time taken for a positive result to be visible in both the new and standard CLOtest. METHODS: Patients presenting for endoscopy at three Western Australian hospitals were prospectively enrolled. Gastric mucosal biopsies were obtained for the standard and new CLOtest and for histology. Grading of color change was conducted by staff blinded to the type of CLOtest used and conducted according to a standardized color chart. Helicobacter pylori status was defined by the combination of a positive standard CLOtest and histology, against which the new CLOtest was compared. Results were obtained at 1, 3 and 24 h, and at one center, at 10 min intervals for the first hour. RESULTS: Three hundred and thirty-five patients were enrolled. Eighty-eight Helicobacter pylori-positive individuals were identified. At 24 h, the new test correctly identified all 88, with one false-positive result (sensitivity 100%, specificity 99.6%). At 1 h, sensitivity was 93% with a number of early false-positive results reducing specificity to 96%. Compared to the current CLOtest, the new formulation became positive faster at 20 min (P = 0.001, n = 51), but was similar at 1 h (P = 0.06, n = 88) and equivalent at 3 h. CONCLUSIONS: The new formulation CLOtest is sensitive and specific, with a trend to give early positive results more quickly, although accuracy at 3 and 24 h is the same.

Biopsy, Needle↗