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Helicobacter pylori is a gram-negative bacterium which causes chronic gastritis and is associated with peptic ulcer disease, gastric carcinoma, and gastric lymphoma. The bacterium is characterized by potent urease activity, thought to be located on the outer membrane, which is essential for survival at low pH. The purpose of the present study was to(More)
Helicobacter pylori is a spiral, gram-negative bacterium which causes chronic gastritis and plays a critical role in peptic ulcer disease, gastric carcinoma, and gastric lymphoma. H. pylori expresses significant urease activity which is an essential virulence factor. Since a significant fraction of urease activity is located on the surface of the bacterium,(More)
OBJECTIVE We prospectively studied an FDA-approved stool test for the diagnosis of Helicobacter pylori infection based on the detection of antigens shed in stool. METHODS We studied 108 patients undergoing endoscopy. Stool samples were collected on the day of the endoscopy and read in a blinded manner by a technician who was unaware of the findings of the(More)
Some strains of Helicobacter pylori are known to produce an extracellular cytotoxin that causes vacuolization in various mammalian cells. In this study, we found that concentrated culture supernatants from four Helicobacter strains isolated from patients infected with the bacterium, but having normal gastric mucosa, lacked cytotoxic activity. We also show(More)
The Helicobacter pylori genome encodes four penicillin-binding proteins (PBPs). PBPs 1, 2, and 3 exhibit similarities to known PBPs. The sequence of PBP 4 is unique in that it displays a novel combination of two highly conserved PBP motifs and an absence of a third motif. Expression of PBP 4, but not PBP 1, 2, or 3, is significantly increased during mid- to(More)
Calprotectin is a protein in neutrophil cytoplasm and abscess fluids that appears to inhibit microbial growth through competition for zinc. This study was undertaken to identify specific sites that might be responsible for the protein's zinc-binding antimicrobial activity. A review of published calprotectin amino acid sequences revealed the HEXXH motif of(More)
Short DNA sequences at ends of transposable elements are needed as sites for transposition. Previous deletion mapping showed that, in Tn5 and its component IS50 elements, these essential sites are about 19 base pairs long. To determine which positions are important in transposition, we made one or more sequence changes at each position in the IS50 outside(More)
The complete genome of the gram-negative bacterial pathogen Helicobacter pylori, an important etiological agent of gastroduodenal disease in humans, has recently been published. This sequence revealed that the putative products of roughly one-third of the open reading frames (ORFs) have no significant homology to any known proteins. To be able to analyze(More)
Helicobacter pylori, an important etiologic agent in a variety of gastroduodenal diseases, produces large amounts of urease as an essential colonization factor. We have demonstrated previously that urease is located within the cytoplasm and on the surface of H. pylori both in vivo and in stationary-phase culture. The purpose of the present study was to(More)
A polymerase chain reaction (PCR) assay for Helicobacter pylori was developed with use of primer sequences from the ureA structural gene coding for the small subunit of urease. The PCR amplification was 100% specific for H. pylori in tests with 40 stock isolates of this species and with 30 control organisms, including two species of urease-producing(More)