Breath Tests: Any tests done on exhaled air.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.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).Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Gastric Emptying: The evacuation of food from the stomach into the duodenum.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Lactulose: A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p887)Aminopyrine: A pyrazolone with analgesic, anti-inflammatory, and antipyretic properties but has risk of AGRANULOCYTOSIS. A breath test with 13C-labeled aminopyrine has been used as a non-invasive measure of CYTOCHROME P-450 metabolic activity in LIVER FUNCTION TESTS.Caprylates: Derivatives of caprylic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated eight carbon aliphatic structure.Hydrogen: The first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic weight [1.00784; 1.00811]. It exists, under normal conditions, as a colorless, odorless, tasteless, diatomic gas. Hydrogen ions are PROTONS. Besides the common H1 isotope, hydrogen exists as the stable isotope DEUTERIUM and the unstable, radioactive isotope TRITIUM.Lactose Intolerance: The condition resulting from the absence or deficiency of LACTASE in the MUCOSA cells of the GASTROINTESTINAL TRACT, and the inability to break down LACTOSE in milk for ABSORPTION. Bacterial fermentation of the unabsorbed lactose leads to symptoms that range from a mild indigestion (DYSPEPSIA) to severe DIARRHEA. Lactose intolerance may be an inborn error or acquired.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.Exhalation: The act of BREATHING out.Dyspepsia: Impaired digestion, especially after eating.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.Carbon Radioisotopes: Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.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.Amoxicillin: A broad-spectrum semisynthetic antibiotic similar to AMPICILLIN except that its resistance to gastric acid permits higher serum levels with oral administration.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.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Bismuth: A metallic element that has the atomic symbol Bi, atomic number 83 and atomic weight 208.98.Urease: An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia. EC 184.108.40.206.Gastrointestinal Transit: Passage of food (sometimes in the form of a test meal) through the gastrointestinal tract as measured in minutes or hours. The rate of passage through the intestine is an indicator of small bowel function.Tinidazole: A nitroimidazole antitrichomonal agent effective against Trichomonas vaginalis, Entamoeba histolytica, and Giardia lamblia infections.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).Chylomicron Remnants: Metabolic products of chylomicron particles in which TRIGLYCERIDES have been selectively removed by the LIPOPROTEIN LIPASE. These remnants carry dietary lipids in the blood and are cholesterol-rich. Their interactions with MACROPHAGES; ENDOTHELIAL CELLS; and SMOOTH MUSCLE CELLS in the artery wall can lead to ATHEROSCLEROSIS.Lactose Tolerance Test: A measure of a patient's ability to break down lactose.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.Malabsorption Syndromes: General term for a group of MALNUTRITION syndromes caused by failure of normal INTESTINAL ABSORPTION of nutrients.Liver Function Tests: Blood tests that are used to evaluate how well a patient's liver is working and also to help diagnose liver conditions.False Negative Reactions: Negative test results in subjects who possess the attribute for which the test is conducted. The labeling of diseased persons as healthy when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)Sulfoxides: Organic compounds that have the general formula R-SO-R. They are obtained by oxidation of mercaptans (analogous to the ketones). (From Hackh's Chemical Dictionary, 4th ed)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).Acetamides: Derivatives of acetamide that are used as solvents, as mild irritants, and in organic synthesis.Duodenal Ulcer: A PEPTIC ULCER located in the DUODENUM.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Drug Therapy, Combination: Therapy with two or more separate preparations given for a combined effect.Gastroparesis: Chronic delayed gastric emptying. Gastroparesis may be caused by motor dysfunction or paralysis of STOMACH muscles or may be associated with other systemic diseases such as DIABETES MELLITUS.Furazolidone: A nitrofuran derivative with antiprotozoal and antibacterial activity. Furazolidone acts by gradual inhibition of monoamine oxidase. (From Martindale, The Extra Pharmacopoeia, 30th ed, p514)Intestine, Small: The portion of the GASTROINTESTINAL TRACT between the PYLORUS of the STOMACH and the ILEOCECAL VALVE of the LARGE INTESTINE. It is divisible into three portions: the DUODENUM, the JEJUNUM, and the ILEUM.Blind Loop Syndrome: A malabsorption syndrome that is associated with a blind loop in the upper SMALL INTESTINE that is characterized by the lack of peristaltic movement, stasis of INTESTINAL CONTENTS, and the overgrowth of BACTERIA. Such bacterial overgrowth interferes with BILE SALTS action, FATTY ACIDS processing, MICROVILLI integrity, and the ABSORPTION of nutrients such as VITAMIN B12 and FOLIC ACID.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Ranitidine: A non-imidazole blocker of those histamine receptors that mediate gastric secretion (H2 receptors). It is used to treat gastrointestinal ulcers.Rabeprazole: A 4-(3-methoxypropoxy)-3-methylpyridinyl 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.Ileocecal Valve: The valve, at the junction of the CECUM with the COLON, that guards the opening where the ILEUM enters the LARGE INTESTINE.Lactose: A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry.Spectrophotometry, Infrared: Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)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.Gastroscopy: Endoscopic examination, therapy or surgery of the interior of the stomach.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.Antitrichomonal Agents: Agents used to treat trichomonas infections.Pentanes: Five-carbon saturated hydrocarbon group of the methane series. Include isomers and derivatives.Breath Holding: An involuntary or voluntary pause in breathing, sometimes accompanied by loss of consciousness.Mineral Waters: Water naturally or artificially infused with mineral salts or gases.Spirulina: A genus of filamentous CYANOBACTERIA found in most lakes and ponds. It has been used as a nutritional supplement particularly due to its high protein content.Loperamide: One of the long-acting synthetic ANTIDIARRHEALS; it is not significantly absorbed from the gut, and has no effect on the adrenergic system or central nervous system, but may antagonize histamine and interfere with acetylcholine release locally.Exocrine Pancreatic Insufficiency: A malabsorption condition resulting from greater than 10% reduction in the secretion of pancreatic digestive enzymes (LIPASE; PROTEASES; and AMYLASE) by the EXOCRINE PANCREAS into the DUODENUM. This condition is often associated with CYSTIC FIBROSIS and with chronic PANCREATITIS.Irritable Bowel Syndrome: A disorder with chronic or recurrent colonic symptoms without a clearcut etiology. This condition is characterized by chronic or recurrent ABDOMINAL PAIN, bloating, MUCUS in FECES, and an erratic disturbance of DEFECATION.Gastritis: Inflammation of the GASTRIC MUCOSA, a lesion observed in a number of unrelated disorders.Methane: The simplest saturated hydrocarbon. It is a colorless, flammable gas, slightly soluble in water. It is one of the chief constituents of natural gas and is formed in the decomposition of organic matter. (Grant & Hackh's Chemical Dictionary, 5th ed)Endoscopy, Gastrointestinal: Endoscopic examination, therapy or surgery of the gastrointestinal tract.Steatorrhea: A condition that is characterized by chronic fatty DIARRHEA, a result of abnormal DIGESTION and/or INTESTINAL ABSORPTION of FATS.Dihydropyrimidine Dehydrogenase Deficiency: An autosomal recessive disorder affecting DIHYDROPYRIMIDINE DEHYDROGENASE and causing familial pyrimidinemia. It is characterized by thymine-uraciluria in homozygous deficient patients. Even a partial deficiency in the enzyme leaves individuals at risk for developing severe 5-FLUOROURACIL-associated toxicity.Phenolsulfonphthalein: Red dye, pH indicator, and diagnostic aid for determination of renal function. It is used also for studies of the gastrointestinal and other systems.Pancreatin: A mammalian pancreatic extract composed of enzymes with protease, amylase and lipase activities. It is used as a digestant in pancreatic malfunction.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Gastrointestinal Motility: The motor activity of the GASTROINTESTINAL TRACT.Propantheline: A muscarinic antagonist used as an antispasmodic, in rhinitis, in urinary incontinence, and in the treatment of ulcers. At high doses it has nicotinic effects resulting in neuromuscular blocking.Respiration: The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).Flatulence: Production or presence of gas in the gastrointestinal tract which may be expelled through the anus.Glutethimide: A hypnotic and sedative. Its use has been largely superseded by other drugs.Diphenoxylate: A MEPERIDINE congener used as an antidiarrheal, usually in combination with ATROPINE. At high doses, it acts like morphine. Its unesterified metabolite difenoxin has similar properties and is used similarly. It has little or no analgesic activity.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Mucositis: An INFLAMMATION of the MUCOSA with burning or tingling sensation. It is characterized by atrophy of the squamous EPITHELIUM, vascular damage, inflammatory infiltration, and ulceration. It usually occurs at the mucous lining of the MOUTH, the GASTROINTESTINAL TRACT or the airway due to chemical irritations, CHEMOTHERAPY, or radiation therapy (RADIOTHERAPY).Intestinal Diseases: Pathological processes in any segment of the INTESTINE from DUODENUM to RECTUM.Gastrointestinal Agents: Drugs used for their effects on the gastrointestinal system, as to control gastric acidity, regulate gastrointestinal motility and water flow, and improve digestion.Liver Cirrhosis: Liver disease in which the normal microcirculation, the gross vascular anatomy, and the hepatic architecture have been variably destroyed and altered with fibrous septa surrounding regenerated or regenerating parenchymal nodules.Achlorhydria: A lack of HYDROCHLORIC ACID in GASTRIC JUICE despite stimulation of gastric secretion.Respiratory Mechanics: The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.Benzimidazoles: Compounds with a BENZENE fused to IMIDAZOLES.Triolein: (Z)-9-Octadecenoic acid 1,2,3-propanetriyl ester.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.Antacids: Substances that counteract or neutralize acidity of the GASTROINTESTINAL TRACT.Pancreatic Extracts: Extracts prepared from pancreatic tissue that may contain the pancreatic enzymes or other specific uncharacterized factors or proteins with specific activities. PANCREATIN is a specific extract containing digestive enzymes and used to treat pancreatic insufficiency.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.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)Biliopancreatic Diversion: A surgical procedure which diverts pancreatobiliary secretions via the duodenum and the jejunum into the colon, the remaining small intestine being anastomosed to the stomach after antrectomy. The procedure produces less diarrhea than does jejunoileal bypass.Esomeprazole: The S-isomer of omeprazole.Sprue, Tropical: A chronic malabsorption syndrome, occurring mainly in residents of or visitors to the tropics or subtropics. The failed INTESTINAL ABSORPTION of nutrients from the SMALL INTESTINE results in MALNUTRITION and ANEMIA that is due to FOLIC ACID deficiency.Tidal Volume: The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are TV or V with subscript T.Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.Erythromycin: A bacteriostatic antibiotic macrolide produced by Streptomyces erythreus. Erythromycin A is considered its major active component. In sensitive organisms, it inhibits protein synthesis by binding to 50S ribosomal subunits. This binding process inhibits peptidyl transferase activity and interferes with translocation of amino acids during translation and assembly of proteins.Mouth: The oval-shaped oral cavity located at the apex of the digestive tract and consisting of two parts: the vestibule and the oral cavity proper.Lactase: An enzyme which catalyzes the hydrolysis of LACTOSE to D-GALACTOSE and D-GLUCOSE. Defects in the enzyme cause LACTOSE INTOLERANCE.