Gastritis: Inflammation of the GASTRIC MUCOSA, a lesion observed in a number of unrelated disorders.Gastritis, Atrophic: GASTRITIS with atrophy of the GASTRIC MUCOSA, the GASTRIC PARIETAL CELLS, and the mucosal glands leading to ACHLORHYDRIA. Atrophic gastritis usually progresses from chronic gastritis.Stomach Ulcer: Ulceration of the GASTRIC MUCOSA due to contact with GASTRIC JUICE. It is often associated with HELICOBACTER PYLORI infection or consumption of nonsteroidal anti-inflammatory drugs (NSAIDS).Duodenal Ulcer: A PEPTIC ULCER located in the DUODENUM.Peptic Ulcer: Ulcer that occurs in the regions of the GASTROINTESTINAL TRACT which come into contact with GASTRIC JUICE containing PEPSIN and GASTRIC ACID. It occurs when there are defects in the MUCOSA barrier. The common forms of peptic ulcers are associated with HELICOBACTER PYLORI and the consumption of nonsteroidal anti-inflammatory drugs (NSAIDS).Helicobacter pylori: A spiral bacterium active as a human gastric pathogen. It is a gram-negative, urease-positive, curved or slightly spiral organism initially isolated in 1982 from patients with lesions of gastritis or peptic ulcers in Western Australia. Helicobacter pylori was originally classified in the genus CAMPYLOBACTER, but RNA sequencing, cellular fatty acid profiles, growth patterns, and other taxonomic characteristics indicate that the micro-organism should be included in the genus HELICOBACTER. It has been officially transferred to Helicobacter gen. nov. (see Int J Syst Bacteriol 1989 Oct;39(4):297-405).Helicobacter Infections: Infections with organisms of the genus HELICOBACTER, particularly, in humans, HELICOBACTER PYLORI. The clinical manifestations are focused in the stomach, usually the gastric mucosa and antrum, and the upper duodenum. This infection plays a major role in the pathogenesis of type B gastritis and peptic ulcer disease.Gastric Mucosa: Lining of the STOMACH, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. The surface cells produce MUCUS that protects the stomach from attack by digestive acid and enzymes. When the epithelium invaginates into the LAMINA PROPRIA at various region of the stomach (CARDIA; GASTRIC FUNDUS; and PYLORUS), different tubular gastric glands are formed. These glands consist of cells that secrete mucus, enzymes, HYDROCHLORIC ACID, or hormones.Leg Ulcer: Ulceration of the skin and underlying structures of the lower extremity. About 90% of the cases are due to venous insufficiency (VARICOSE ULCER), 5% to arterial disease, and the remaining 5% to other causes.Pressure Ulcer: An ulceration caused by prolonged pressure on the SKIN and TISSUES when one stays in one position for a long period of time, such as lying in bed. The bony areas of the body are the most frequently affected sites which become ischemic (ISCHEMIA) under sustained and constant pressure.Skin UlcerPeptic Ulcer Hemorrhage: Bleeding from a PEPTIC ULCER that can be located in any segment of the GASTROINTESTINAL TRACT.Pyloric Antrum: The region between the sharp indentation at the lower third of the STOMACH (incisura angularis) and the junction of the PYLORUS with the DUODENUM. Pyloric antral glands contain mucus-secreting cells and gastrin-secreting endocrine cells (G CELLS).Stomach: An organ of digestion situated in the left upper quadrant of the abdomen between the termination of the ESOPHAGUS and the beginning of the DUODENUM.Gastroscopy: Endoscopic examination, therapy or surgery of the interior of the stomach.Gastritis, Hypertrophic: GASTRITIS with HYPERTROPHY of the GASTRIC MUCOSA. It is characterized by giant gastric folds, diminished acid secretion, excessive MUCUS secretion, and HYPOPROTEINEMIA. Symptoms include VOMITING; DIARRHEA; and WEIGHT LOSS.Metaplasia: A condition in which there is a change of one adult cell type to another similar adult cell type.Peptic Ulcer Perforation: Penetration of a PEPTIC ULCER through the wall of DUODENUM or STOMACH allowing the leakage of luminal contents into the PERITONEAL CAVITY.Pepsinogen A: This is one of 2 related pepsinogen systems in humans and is also known as pepsinogen. (The other is PEPSINOGEN C.) This includes isozymogens Pg1-Pg5 (pepsinogens 1-5, group I or products of PGA1-PGA5 genes). This is the main pepsinogen found in urine.Stomach Neoplasms: Tumors or cancer of the STOMACH.Buruli Ulcer: A lesion in the skin and subcutaneous tissues due to infections by MYCOBACTERIUM ULCERANS. It was first reported in Uganda, Africa.Achlorhydria: A lack of HYDROCHLORIC ACID in GASTRIC JUICE despite stimulation of gastric secretion.Gastrins: A family of gastrointestinal peptide hormones that excite the secretion of GASTRIC JUICE. They may also occur in the central nervous system where they are presumed to be neurotransmitters.Bile Reflux: Retrograde bile flow. Reflux of bile can be from the duodenum to the stomach (DUODENOGASTRIC REFLUX); to the esophagus (GASTROESOPHAGEAL REFLUX); or to the PANCREAS.Anti-Ulcer Agents: Various agents with different action mechanisms used to treat or ameliorate PEPTIC ULCER or irritation of the gastrointestinal tract. This has included ANTIBIOTICS to treat HELICOBACTER INFECTIONS; HISTAMINE H2 ANTAGONISTS to reduce GASTRIC ACID secretion; and ANTACIDS for symptomatic relief.Gastric Juice: The liquid secretion of the stomach mucosa consisting of hydrochloric acid (GASTRIC ACID); PEPSINOGENS; INTRINSIC FACTOR; GASTRIN; MUCUS; and the bicarbonate ion (BICARBONATES). (From Best & Taylor's Physiological Basis of Medical Practice, 12th ed, p651)Dyspepsia: Impaired digestion, especially after eating.Pepsinogen C: This is one of the 2 related pepsinogen systems in humans. It is found in prostate and seminal fluid whereas PEPSINOGEN A is not.Duodenitis: Inflammation of the DUODENUM section of the small intestine (INTESTINE, SMALL). Erosive duodenitis may cause bleeding in the UPPER GI TRACT and PEPTIC ULCER.Stomach Diseases: Pathological processes involving the STOMACH.Parietal Cells, Gastric: Rounded or pyramidal cells of the GASTRIC GLANDS. They secrete HYDROCHLORIC ACID and produce gastric intrinsic factor, a glycoprotein that binds VITAMIN B12.Helicobacter heilmannii: A species of gram-negative, spiral-shaped bacteria found in the gastric mucosa that is associated with chronic antral gastritis. This bacterium was first discovered in samples removed at endoscopy from patients investigated for HELICOBACTER PYLORI colonization.Anemia, Pernicious: A megaloblastic anemia occurring in children but more commonly in later life, characterized by histamine-fast achlorhydria, in which the laboratory and clinical manifestations are based on malabsorption of vitamin B 12 due to a failure of the gastric mucosa to secrete adequate and potent intrinsic factor. (Dorland, 27th ed)Helicobacter felis: A species of HELICOBACTER that colonizes in the STOMACH of laboratory MICE; CATS; and DOGS. It is associated with lymphoid follicular hyperplasia and mild GASTRITIS in CATS.Gastric Acid: Hydrochloric acid present in GASTRIC JUICE.Pepsinogens: Proenzymes secreted by chief cells, mucous neck cells, and pyloric gland cells, which are converted into pepsin in the presence of gastric acid or pepsin itself. (Dorland, 28th ed) In humans there are 2 related pepsinogen systems: PEPSINOGEN A (formerly pepsinogen I or pepsinogen) and PEPSINOGEN C (formerly pepsinogen II or progastricsin). Pepsinogen B is the name of a pepsinogen from pigs.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Chronic Disease: Diseases which have one or more of the following characteristics: they are permanent, leave residual disability, are caused by nonreversible pathological alteration, require special training of the patient for rehabilitation, or may be expected to require a long period of supervision, observation, or care. (Dictionary of Health Services Management, 2d ed)Urease: An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia. EC 3.5.1.5.Omeprazole: A 4-methoxy-3,5-dimethylpyridyl, 5-methoxybenzimidazole derivative of timoprazole that is used in the therapy of STOMACH ULCERS and ZOLLINGER-ELLISON SYNDROME. The drug inhibits an H(+)-K(+)-EXCHANGING ATPASE which is found in GASTRIC PARIETAL CELLS.Helicobacter: A genus of gram-negative, spiral-shaped bacteria that has been isolated from the intestinal tract of mammals, including humans. It has been associated with PEPTIC ULCER.Postgastrectomy Syndromes: Sequelae of gastrectomy from the second week after operation on. Include recurrent or anastomotic ulcer, postprandial syndromes (DUMPING SYNDROME and late postprandial hypoglycemia), disordered bowel action, and nutritional deficiencies.Endoscopy: Procedures of applying ENDOSCOPES for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. transluminal, to examine or perform surgery on the interior parts of the body.Amoxicillin: A broad-spectrum semisynthetic antibiotic similar to AMPICILLIN except that its resistance to gastric acid permits higher serum levels with oral administration.Diabetic Foot: Common foot problems in persons with DIABETES MELLITUS, caused by any combination of factors such as DIABETIC NEUROPATHIES; PERIPHERAL VASCULAR DISEASES; and INFECTION. With the loss of sensation and poor circulation, injuries and infections often lead to severe foot ulceration, GANGRENE and AMPUTATION.Precancerous Conditions: Pathological processes that tend eventually to become malignant. (From Dorland, 27th ed)Gastroenterostomy: A variety of surgical reconstructive procedures devised to restore gastrointestinal continuity, The two major classes of reconstruction are the Billroth I (gastroduodenostomy) and Billroth II (gastrojejunostomy) procedures.Endoscopy, Gastrointestinal: Endoscopic examination, therapy or surgery of the gastrointestinal tract.Campylobacter: A genus of bacteria found in the reproductive organs, intestinal tract, and oral cavity of animals and man. Some species are pathogenic.Bismuth: A metallic element that has the atomic symbol Bi, atomic number 83 and atomic weight 208.98.Antigens, Bacterial: Substances elaborated by bacteria that have antigenic activity.Atrophy: Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes.Gastric Acidity Determination: Gastric analysis for determination of free acid or total acid.Cimetidine: A histamine congener, it competitively inhibits HISTAMINE binding to HISTAMINE H2 RECEPTORS. Cimetidine has a range of pharmacological actions. It inhibits GASTRIC ACID secretion, as well as PEPSIN and GASTRIN output.Antacids: Substances that counteract or neutralize acidity of the GASTROINTESTINAL TRACT.Acinonyx: A genus of long-legged, swift-moving felines (FELIDAE) from Africa (and formerly Asia) about the size of a small leopard.Vagotomy: The interruption or removal of any part of the vagus (10th cranial) nerve. Vagotomy may be performed for research or for therapeutic purposes.H(+)-K(+)-Exchanging ATPaseDuodenum: The shortest and widest portion of the SMALL INTESTINE adjacent to the PYLORUS of the STOMACH. It is named for having the length equal to about the width of 12 fingers.Mycobacterium ulcerans: A slow-growing mycobacterium that infects the skin and subcutaneous tissues, giving rise to indolent BURULI ULCER.Duodenogastric Reflux: Retrograde flow of duodenal contents (BILE ACIDS; PANCREATIC JUICE) into the STOMACH.Ranitidine: A non-imidazole blocker of those histamine receptors that mediate gastric secretion (H2 receptors). It is used to treat gastrointestinal ulcers.Duodenoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the duodenum.Clarithromycin: A semisynthetic macrolide antibiotic derived from ERYTHROMYCIN that is active against a variety of microorganisms. It can inhibit PROTEIN SYNTHESIS in BACTERIA by reversibly binding to the 50S ribosomal subunits. This inhibits the translocation of aminoacyl transfer-RNA and prevents peptide chain elongation.Gastric Fundus: The superior portion of the body of the stomach above the level of the cardiac notch.Antibodies, Bacterial: Immunoglobulins produced in a response to BACTERIAL ANTIGENS.Proton Pump Inhibitors: Compounds that inhibit H(+)-K(+)-EXCHANGING ATPASE. They are used as ANTI-ULCER AGENTS and sometimes in place of HISTAMINE H2 ANTAGONISTS for GASTROESOPHAGEAL REFLUX.Gastrointestinal Diseases: Diseases in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Autoimmune Diseases: Disorders that are characterized by the production of antibodies that react with host tissues or immune effector cells that are autoreactive to endogenous peptides.Vagotomy, Proximal Gastric: Vagal denervation of that part of the STOMACH lined with acid-secreting mucosa (GASTRIC MUCOSA) containing the GASTRIC PARIETAL CELLS. Since the procedure leaves the vagal branches to the antrum and PYLORUS intact, it circumvents gastric drainage required with truncal vagotomy techniques.Gastrointestinal Hemorrhage: Bleeding in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.2-Pyridinylmethylsulfinylbenzimidazoles: Compounds that contain benzimidazole joined to a 2-methylpyridine via a sulfoxide linkage. Several of the compounds in this class are ANTI-ULCER AGENTS that act by inhibiting the POTASSIUM HYDROGEN ATPASE found in the PROTON PUMP of GASTRIC PARIETAL CELLS.Pylorus: The region of the STOMACH at the junction with the DUODENUM. It is marked by the thickening of circular muscle layers forming the pyloric sphincter to control the opening and closure of the lumen.Lansoprazole: A 2,2,2-trifluoroethoxypyridyl derivative of timoprazole that is used in the therapy of STOMACH ULCERS and ZOLLINGER-ELLISON SYNDROME. The drug inhibits H(+)-K(+)-EXCHANGING ATPASE which is found in GASTRIC PARIETAL CELLS. Lansoprazole is a racemic mixture of (R)- and (S)-isomers.Bacterial Proteins: Proteins found in any species of bacterium.Bandages: Material used for wrapping or binding any part of the body.Endoscopy, Digestive System: Endoscopic examination, therapy or surgery of the digestive tract.Metronidazole: A nitroimidazole used to treat AMEBIASIS; VAGINITIS; TRICHOMONAS INFECTIONS; GIARDIASIS; ANAEROBIC BACTERIA; and TREPONEMAL INFECTIONS. It has also been proposed as a radiation sensitizer for hypoxic cells. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985, p133), this substance may reasonably be anticipated to be a carcinogen (Merck, 11th ed).Intrinsic Factor: A glycoprotein secreted by the cells of the GASTRIC GLANDS that is required for the absorption of VITAMIN B 12 (cyanocobalamin). Deficiency of intrinsic factor leads to VITAMIN B 12 DEFICIENCY and ANEMIA, PERNICIOUS.Anti-Inflammatory Agents, Non-Steroidal: Anti-inflammatory agents that are non-steroidal in nature. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions.They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins. Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects.Histamine H2 Antagonists: Drugs that selectively bind to but do not activate histamine H2 receptors, thereby blocking the actions of histamine. Their clinically most important action is the inhibition of acid secretion in the treatment of gastrointestinal ulcers. Smooth muscle may also be affected. Some drugs in this class have strong effects in the central nervous system, but these actions are not well understood.Duodenal Diseases: Pathological conditions in the DUODENUM region of the small intestine (INTESTINE, SMALL).Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Thymectomy: Surgical removal of the thymus gland. (Dorland, 28th ed)Campylobacter Infections: Infections with bacteria of the genus CAMPYLOBACTER.Gastroesophageal Reflux: Retrograde flow of gastric juice (GASTRIC ACID) and/or duodenal contents (BILE ACIDS; PANCREATIC JUICE) into the distal ESOPHAGUS, commonly due to incompetence of the LOWER ESOPHAGEAL SPHINCTER.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Esophagitis: INFLAMMATION, acute or chronic, of the ESOPHAGUS caused by BACTERIA, chemicals, or TRAUMA.Famotidine: A competitive histamine H2-receptor antagonist. Its main pharmacodynamic effect is the inhibition of gastric secretion.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Lymphocytosis: Excess of normal lymphocytes in the blood or in any effusion.Upper Gastrointestinal Tract: The segment of GASTROINTESTINAL TRACT that includes the ESOPHAGUS; the STOMACH; and the DUODENUM.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Recurrence: The return of a sign, symptom, or disease after a remission.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Acetic Acid: Product of the oxidation of ethanol and of the destructive distillation of wood. It is used locally, occasionally internally, as a counterirritant and also as a reagent. (Stedman, 26th ed)Gastrin-Secreting Cells: Endocrine cells which secrete GASTRIN, a peptide that induces GASTRIC ACID secretion. They are found predominantly in the GASTRIC GLANDS of PYLORIC ANTRUM in the STOMACH, but can also be found in the DUODENUM, nervous and other tissues.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.