Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to identify the natural reservoir and route of transmission of Helicobacter pylori infection. Two hundred eight (208) dyspeptic patients (114 males, 94 females; peak age of cohort, 50-59.9) were recruited. Specimens were collected from saliva, supra- and subgingival dental plaque, tongue scrapings, and oropharyngeal swabs. At subsequent endoscopy, gastric antral biopsy was performed for the rapid urease test (RUT), microbiological culture, and, in some patients, histology. Gastric juice samples were aspirated, and in 50 patients duodenal aspirate was collected. Polymerase chain reaction (PCR) with primers targeted to the 16S rRNA sequence of H. pylori was also employed for each of the specimens. In those patients where H. pylori was detected from multiple sites (dental plaque, gastric juice, gastric biopsy, and duodenal aspirate), restriction endonuclease digestion with Hae III was performed to determine if they were epidemiologically linked. The results indicated that 15/208 patients (7%) tested positively for H. pylori by PCR in dental plaque; only 2 samples were positive by culture. In none of the other oral sites sampled was H. pylori detected by any test used in the study. Gastric juice and gastric biopsy specimens from 36/ 208 patients (17%) and 114/208 patients (55%), respectively, were positive by PCR. Duodenal aspirate from 6/50 patients (12%) also tested positively by PCR. All specimens tested by restriction endonuclease digestion with Hae III (15/15 patients) were positive in both antral biopsy and gastric juice specimens, as well as 5 specimens from the duodenal aspirate. Four of the dental plaque strains had restriction patterns similar to those of the stomach and duodenal sites, providing evidence that these sites were infected with the same strain of H. pylori. In conclusion, the results suggest that H. pylori selects the gastric mucosa as its preferred site. The detection in dental plaque could indicate that the oral cavity may act as a reservoir or sanctuary for the organism. Whether H. pylori is a resident or transient oral microorganism is still unclear, although it is more likely to be transient in nature.
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PMID:Helicobacter pylori: the mouth, stomach, and gut axis. 972 11

The aim of the present work was to develop polymerase chain reactions (PCRs) based on the conserved nucleotide sequence of the 16S rRNA gene for detection of bacteria of the Helicobacter genus in human antral biopsy samples. The assay for Helicobacter spp was developed by amplifying a 399-bp 16S rRNA gene sequence specific to the genus Helicobacter. The identity of the amplicon was confirmed by hybridization with an internal probe and by restriction by endonuclease VspI showing two expected fragments of 295 and 104 base pairs. A total of 65 dyspeptic patients from France and New Caledonia were screened for Helicobacter spp infection through the use of the following diagnostic assays on biopsy specimens collected through endoscopy: direct detection of bacteria in histological sections by Giemsa and Warthin Starry staining, urease test and bacterial isolation, PCR for Helicobacter pylori ureC/glmM gene, and PCR targeted to 16S rRNA genes. The 16S rRNA gene PCR assay was able to detect down to 680 bacterial cells, as assessed by agarose gel electrophoresis, and down to 4 bacterial cells by hybridization of amplicon with the internal probe. The 16S rRNA PCR test was 100% specific and sensitive; results obtained with this test were in agreement with the visualization of bacteria by histology. Urease test and culture were 86.4% and 22.7% sensitive, and 96.5 and 100% specific, respectively. The H. pylori ureC/glmM gene-based PCR was 100% specific and only 95.4% sensitive, since one biopsy from a Melanesian patient contained a Helicobacter strain other than H. pylori. For this Melanesian patient, a branch-specific PCR targeting the epsilon branch of Proteobacteria was used to amplify a 967-bp amplicon. This amplicon was sequenced and matched with the H. felis sequence. This was confirmed using an H. felis-specific urease PCR test.
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PMID:Strategy for the detection of Helicobacter species by amplification of 16S rRNA genes and identification of H. felis in a human gastric biopsy. 976 10

Microbial typing is a useful tool in clinical epidemiology for defining the source and route of infection, for studying the persistence and reinfection rates, clonal selection in the host and bacterial evolution. Phenotypic methods such as biotyping, serotyping and hemagglutinin typing have little discriminatory power compared to genotypic methods concerning the typing of Helicobacter pylori. Therefore great efforts have been made to establish useful molecular typing methods. In this context, the most frequently used genotypic methods are described based on our own experience and the literature: (1) restriction endonuclease analysis, (2) endonuclease analysis using pulsed-field gel electrophoresis, (3) ribotyping, (4) polymerase chain reaction (using either random primers or repetitive DNA sequence primers), and (5) polymerase chain reaction-restriction fragment length polymorphism analysis of e.g. the urease genes. Furthermore, reproducibility, discriminatory power, ease of performance and interpretation, cost and toxic procedures of each method are assessed. To date no direct comparison of all the molecular typing methods described has been performed in the same study with the same H. pylori strains. However, PCR analysis of the urease gene directly on suspensions of H. pylori or gastric biopsy material seems to be useful for routine use and applicable in specific epidemiological situations.
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PMID:Molecular methods for typing of Helicobacter pylori and their applications. 1037 20

Since Helicobacter pylori was first described in 1983 (1), the study of genomic DNA has been central to the development of its microbiology and molecular genetics. For instance, DNA base composition estimation (mol% G+C) was crucial in demonstrating affinities of the microorganism to the genus Campylobacter (2). Likewise, DNA-DNA hybridization assays revealed a high degree of base sequence homology between different isolates of H. pylori, yet a low relatedness to Campylobacter fetus and other species of Campylobacter (3). In 1987, rRNA-DNA hybridization and hybrid thermal stability analyses were used to show that H. pylori was phylogenetically distinct from Campylobacter sensu stricto and that the species merited classification in a new genus (4). The most significant application of DNA analysis has been in showing the diversity between genomes of different strains within H. pylori. The first indication of such genome diversity was from restriction endonuclease digest analysis of genomic DNA (6) and was subsequently confirmed by ribosomal RNA gene analysis and polymerase chain reaction (PCR)-based analysis of urease and other genes (7).
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PMID:Isolation of H. pylori Genomic DNA and Restriction Analysis. 2135 Oct 24


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