The present study was conducted to elucidate the mechanisms by which Helicobacter pylori (HP)-derived ammonia causes gastric mucosal injury. Intact sheets of guinea pig gastric fundic mucosae were incubated in Ussing chambers. Both the luminal and the serosal pH were kept at 7.4. Transmucosal potential difference (PD) and electrical resistance (R) were monitored as indices of mucosal integrity....

The ulcer-inducing bacterium Helicobacter pylori busts through the cells that line the stomach by hijacking a host protein, suggest Suzuki and colleagues on page 1235. The co-opted protein turns on multiple signaling pathways in gastric cells that cause the normally adhesive cells to pull apart from their neighbors. Roughly half of all people worldwide have H. pylori living in their stomachs. M...

The expression of hypoxia inducible factor (HIF)-1 protein is tightly regulated by cellular oxygen status. Namely, HIF-1 protein is degraded rapidly in normoxic cells, whereas hypoxia stabilizes HIF-1 to transactivate hypoxia-responsive genes. Here we show that HIF-1 protein is expressed aberrantly in gastric cancer cells under normoxia in a reactive oxygen species (ROS)-dependent manner. The n...

The Epstein-Barr virus (EBV) is detected in the tissue of about 10% of gastric carcinoma cases throughout the world. In each case, 100% of carcinoma cells are infected with EBV. Analysis of EBV in carcinoma biopsies indicates that carcinoma is formed by the proliferation of a single EBV infected cell. These findings suggest that EBV plays an important role in the development of EBV positive gas...

Gastric luminal ammonia produced by Helicobacter pylori has been shown to cause gastric mucosal injury. This study was conducted to examine the mechanisms by which gastric luminal ammonia causes apoptosis of gastric epithelial cells. Monolayers of GSM06 cells, developed from murine gastric surface mucous cells, were cultured in the absence or presence of 10-30 mM NH(4)Cl at ambient pH of 5.0, 6...

Epithelial organization is maintained by cell proliferation, migration, and differentiation. In the case of the gastric epithelium, at least some of these events are regulated by the hormone gastrin. In addition, gastric epithelial cells are organized into characteristic tubular structures (the gastric glands), but the cellular mechanisms regulating the organization of tubular structures (somet...

The Epstein-Barr virus (EBV) is detected in the tissue of about 10% of gastric carcinoma cases throughout the world. In each case, 100% of carcinoma cells are infected with EBV. Analysis of EBV in carcinoma biopsies indicates that carcinoma is formed by the proliferation of a single EBV infected cell. These findings suggest that EBV plays an important role in the development of EBV positive gas...

The mechanisms involved in mediating the enhanced gastric epithelial cell apoptosis observed during infection with Helicobacter pylori in vivo are unknown. To determine whether H. pylori directly induces apoptosis of gastric epithelial cells in vitro and to define the role of the Fas-Fas ligand signal transduction cascade, human gastric epithelial cells were infected with H. pylori for up to 72...

Gastric mucosal health is maintained in response to potentially damaging luminal factors. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) disrupt protective mechanisms leading to bleeding and ulceration. The plasminogen activator system has been implicated in fibrinolysis following gastric ulceration, and an inhibitor of this system, plasminogen activator inhibitor (PAI)-1, is express...