Non-pylori Helicobacteraceae in the upper digestive tract of asymptomatic Venezuelan subjects: detection of Helicobacter cetorum-like and Candidatus Wolinella africanus-like DNA

BACKGROUND: The spectrum of human non-pylori Helicobacter infections is expanding, with species such as H. heilmannii and H. felis occasionally being associated with gastritis. However, the existence of non-pylori Helicobacter colonization in asymptomatic subjects has not been evaluated. The aim of this study was to investigate whether Helicobacter species other than pylori are present in the upper digestive tract of asymptomatic human subjects. MATERIALS AND METHODS: A Helicobacteraceae-specific semi-nested polymerase chain reaction (PCR) assay was used to detect Helicobacter-like organisms in the upper digestive tract of 91 Venezuelan volunteers (aged 18-68 years, 41 females, 50 males). Species were identified by denaturing gradient gel electrophoresis analysis and sequencing of the PCR products. RESULTS: We detected DNA sharing 99-100% sequence identity in over 300-400 bp with the 16S rRNA genes of H. pylori, H. cetorum, and Candidatus Wolinella africanus in 76%, 16%, and 15% of the subjects, respectively. Multiple colonization was documented in 10% of the subjects: H. cetorum and Candidatus W. africanus (4%), H. pylori and Candidatus W. africanus (4%), and H. pylori and H. cetorum (2%). CONCLUSIONS: Our results suggest that non-pylori Helicobacteraceae colonization is relatively common in the Venezuelan asymptomatic population. This is the first report documenting the presence of H. cetorum DNA in the human upper digestive tract, and the second report of the recently discovered Candidatus W. africanus.     

Does Helicobacter pylori infection per se cause gastric cancer or duodenal ulcer? Inadequate evidence in Mongolian gerbils and inbred mice

A role for Helicobacter pylori infection in the development of gastric cancer in humans is well established; however, evidence for its carcinogenicity in animals remains inadequate. Mongolian gerbils and mice are commonly used to investigate the carcinogenicity of H. pylori, yet it is unclear whether H. pylori infection per se causes gastric cancer or duodenal ulcers in these animal models. Gastric adenocarcinoma in the gerbils was reported over 10 years ago, but this species has proved an unreliable model for studying H. pylori infection-associated gastric cancer. Helicobacter pylori infection alone appears insufficient to induce gastric cancer in these animals; additional carcinogenic insult is required. The development of invasive adenocarcinoma in inbred mice is rare regardless of the mouse or bacterial strain, and many long-term studies have failed to induce gastric cancer in these animals. Helicobacter pylori infection is also an established causative factor for duodenal ulcer in humans. However, few studies have attempted to develop animal models of H. pylori infection-induced duodenal ulcer. We therefore conclude that both Mongolian gerbils and inbred mice may be inadequate models for studying H. pylori infection-associated gastric cancer and that there is no animal model of H. pylori infection-induced duodenal ulcer.     

Immunological properties of the cell surface haemagglutinins (sHAs) of Helicobacter pylori strain NCTC 11637

Abstract Rabbits were immunised with stage 1 and stage 2 soluble haemagglutinins (sHA) of Helicobacter pylori strain NCTC 11637 and with rabbit erythrocytes coated with stage 1 sHA. After adsorption of stage 1 sHA on erythrocytes, SDS-PAGE analysis showed that 4 major protein bands were removed from the preparation. The anti-sHA coated erythrocyte serum had the highest HA inhibition titre of 16. Crossed immunoelectrophoresis of the stage 1 sHA, against stage 1 and 2 antisera showed multiple precipitin arcs; however, the anti-sHA coated erythrocyte serum produced only two arcs. One arc produced by the anti-stage 2 serum was absent with the anti-stage 1 serum. This arc could have been produced against a 20 kDa polypeptide which was absent in the stage 1 sHA. The other arc was stronger when compared with that produced by anti-stage 1 serum. These two arcs corresponded to the two arcs produced by the anti-sHA coated erythrocyte serum, which had the highest inhibition titre. The two arcs were markedly reduced in crossed immunoelectrophoresis with an adsorbed stage 1 sHA preparation, which indicates that these arcs were produced against the sHAs.     

Qualitative assessment of the diet of European eel larvae in the Sargasso Sea resolved by DNA barcoding

European eels (Anguilla anguilla) undertake spawning migrations of more than 5000 km from continental Europe and North Africa to frontal zones in the Sargasso Sea. Subsequently, the larval offspring are advected by large-scale eastward ocean currents towards continental waters. However, the Sargasso Sea is oligotrophic, with generally low plankton biomass, and the feeding biology of eel larvae has so far remained a mystery, hampering understanding of this peculiar life history. DNA barcoding of gut contents of 61 genetically identified A. anguilla larvae caught in the Sargasso Sea showed that even the smallest larvae feed on a striking variety of plankton organisms, and that gelatinous zooplankton is of fundamental dietary importance. Hence, the specific plankton composition seems essential for eel larval feeding and growth, suggesting a linkage between eel survival and regional plankton productivity. These novel insights into the prey of Atlantic eels may furthermore facilitate eel larval rearing in aquaculture, which ultimately may replace the unsustainable use of wild-caught glass eels.     

Detection of staphylococcus aureus infection by enzyme-linked immunosorbent assay and immunoblotting, using high molecular weight staphylococcal proteins

Abstract Two high molecular weight staphylococcal proteins, fibronectin-binding protein and a M _τ 200 000 protein, were investigated as antigens for serodiagnosis of staphylococcal infections. Sera from patients with staphylococcal infections and from controls were subjected to immunoblot analysis with staphylococcal lysate proteins to identify staphylococcal antigens to which patients with staphylococcal infections specifically exhibited antibodies. On such protein was found in the M _τ 200 000 region. This protein was purified and used as antigen in ElISA and compared with other antigens, namely fibronectin-binding protein(s) (FNBP, M _τ , 185 000), α-toxin and teichoic acid. Sera from patients with staphylococcal infections contained antibodies to the high molecular weight proteins in higher titers than sera from patients with non-staphylococcal infections or healthy subjects. Based on their amino-acid compositions and different abilities to bind fibronectin it was concluded that the M _τ 200 000 protein and FNBP were not identical.     

High surface hydrophobicity of hemagglutinatingVibrio cholerae and other vibrios

Surface hydrophobicity of hemagglutinatingVibrio cholerae, Vibrio parahaemolyticus, and NAG vibrios has been investigated. Most strains caused mannose-sensitive hemagglutination of monkey, guinea pig, chicken, and mannose-resistant hemagglutination of human erythrocytes with different degrees of hemagglutinating activity. Hemagglutinating strains adsorbed to a hydrophobic gel (Octyl Sepharose), whereas nonhemagglutinating strains failed to adsorb.Vibrio cholerae and other vibrios investigated seem to have pronounced surface hydrophobicity as estimated by Octyl Sepharose and they correspondingly autoaggregated into visible cell clumps in ammonium sulfate solution at low molarity (0.2–0.4 M). Nonhemagglutinating strains did not aggregate even at high (2 M) ammonium sulfate concentration. The presence of surface hemagglutinins of vibrios is growth-media-dependent. Strains, grown in four different liquid media, produced hemagglutinins and expressed pronounced surface hydrophobicity. Studies with electron microscopy revealed the presence of fimbriae on the vibrio cells. The number of fimbriae on the cells varied from strain to strain. Some strains possessed more than 300 fimbriae/cell whereas others had less than 10 fimbriae/cell. Vibrio hemagglutinins are easily detached from the cell surface by heating or sonication, and their cell surface hydrophobicity decreased simultaneously.     

Microscale patchiness of plankton within a sharp pycnocline

Microscale distributions of plankton around the pycnocline werestudied over a 24 h period in the southern Kattegat, using agradient sampler which collects 20 samples over a 3 m depthinterval. Moderately elevated concentrations of phyto- and zooplanktonwere observed at the pycnocline. Microscale variance was highestfor adult copepods. Nauplii and copepodites were equally wellrepresented by sampling with ordinary vertical 5 1 water bottlesas with the horizontal 1.5 1 bottles of the gradient sampler.Adult copepods were underestimated by the vertical bottles.No vertical migration of dinoflagellates was observed over the3 m interval covered by the gradient sampler. Microscale correlationsbetween copepods and phytoplankton within the gradient samplerwere weak. Copepodites (mainly Oithona sp.) and the dinoflagellateProrocentrum micans showed the best correlation.     

Gastrointestinal colonisation of BALB/cA mice by Helicobacter pylori monitored by heparin magnetic separation

Abstract Immunocompetent and immunodeficient BALB/cA mice were fed orally with 10⁸ colony forming units of 2-day-old spiral or coccoid (12 days old) Helicobacter pylori strain NCTC 11637. Immunocompetent BALB/cA mice were also fed orally with decreasing numbers of spiral or coccoid forms of H. pylori . The gastrointestinal colonisation process was monitored for 34 days post-infection by heparin magnetic separation and subsequent enzyme immunoassay (EIA) for the detection of the H. pylori cells. Both mice types were colonised with H. pylori . The coccoid form of H. pylori gave higher EIA absorbance values and more efficient colonisation in the mice than the spiral form. Immunocompetent BALB/cA mice fed with the coccoid form of H. pylori exhibited an acute inflammation process in histopathological samples from the stomachs. In conclusion, H. pylori can infect both immunocompetent as well as immunodeficient BALB/cA mice and coccoids (viable but non-culturable) obtained after 12 days of culturing can infect BALB/cA mice.     

Immunochemical properties of a 60 kDa cell surface-associated heat shock-protein (Hsp60) from Helicobacter pylori

Abstract Western blot analysis (immunoblotting) of cell surface-associated proteins from Helicobacter pylori confirmed our previous findings that binding of human IgG is a common property (among H. pylori strains). Purification of the IgG-binding proteins (IGBP) was achieved by two purification steps, affinity chromatography on IgG-Sepharose and nickel chelate affinity chromatography. SDS-PAGE and immunoblotting analysis revealed a 60 kDa protein with affinity for peroxidase labeled human IgG. Solid phase binding assays showed that IgG binds to an immobilized protein (IGBP). The 60 kDa IGBP binds human IgG₁, IgG₃ and IgM. Binding could be inhibited by the kappa chain of the human IgG, but not with its Fc fragment, nor with IgA or IgM. In addition, rabbit polyclonal antibodies raised against the 60 kDa IGBP blocked IgG binding. Monoclonal antibodies, specific to the Hsp60 heat shock protein of H. pylori recognized the 60 kDa IGBP as revealed by immunoblotting analysis, both in crude preparations and in the purified fractions.     

Adhesion ofHelicobacter pylori strains toα-2,3-linked sialic acids

Helicobacter pylori is a human pathogen associated with gastritis and peptic ulcer. Adhesion properties ofH. pylori to various structures have been described in the literature, including evidence for sialic acid-binding. To study the specificity and frequency of sialic acid-binding, fourteenH. pylori strains were investigated using haemagglutination with derivatized erythrocytes carrying sialic acids only on defined glycans and using haemagglutination inhibition assays. From these studiesH. pylori strains can be grouped into sialic acid-dependent and sialic acid-independent classes. The sialic acid-dependent strains require -2,3-linked sialic acid for haemagglutination. The potential roles of sialic acid-dependent adhesions forH. pylori-related infections are discussed.Abbreviations Sia sialic acids - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolylneuraminic acid - Neu5Fm N-formylneuraminic acid - Neu5TFA N-trifluoroacetylneuraminic acid - RBC human red blood cells (erythrocytes)