2,3-Diketogulonic Acid: Metabolite of ASCORBIC ACID and the oxidized form of the lactone DEHYDROASCORBIC ACID.Dictionaries, MedicalDictionaries as Topic: Lists of words, usually in alphabetical order, giving information about form, pronunciation, etymology, grammar, and meaning.Drug Information Services: Services providing pharmaceutic and therapeutic drug information and consultation.National Library of Medicine (U.S.): An agency of the NATIONAL INSTITUTES OF HEALTH concerned with overall planning, promoting, and administering programs pertaining to advancement of medical and related sciences. Major activities of this institute include the collection, dissemination, and exchange of information important to the progress of medicine and health, research in medical informatics and support for medical library development.Counterfeit Drugs: Drugs manufactured and sold with the intent to misrepresent its origin, authenticity, chemical composition, and or efficacy. Counterfeit drugs may contain inappropriate quantities of ingredients not listed on the label or package. In order to further deceive the consumer, the packaging, container, or labeling, may be inaccurate, incorrect, or fake.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.Government Agencies: Administrative units of government responsible for policy making and management of governmental activities.MEDLARS: A computerized biomedical bibliographic storage and retrieval system operated by the NATIONAL LIBRARY OF MEDICINE. MEDLARS stands for Medical Literature Analysis and Retrieval System, which was first introduced in 1964 and evolved into an online system in 1971 called MEDLINE (MEDLARS Online). As other online databases were developed, MEDLARS became the name of the entire NLM information system while MEDLINE became the name of the premier database. MEDLARS was used to produce the former printed Cumulated Index Medicus, and the printed monthly Index Medicus, until that publication ceased in December 2004.Portal Vein: A short thick vein formed by union of the superior mesenteric vein and the splenic vein.Gas Chromatography-Mass Spectrometry: A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Ascorbic Acid: A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Chromatography, Liquid: Chromatographic techniques in which the mobile phase is a liquid.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.Disease Transmission, Infectious: The transmission of infectious disease or pathogens. When transmission is within the same species, the mode can be horizontal or vertical (INFECTIOUS DISEASE TRANSMISSION, VERTICAL).Metals: Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed)Composite Resins: Synthetic resins, containing an inert filler, that are widely used in dentistry.Materials Testing: The testing of materials and devices, especially those used for PROSTHESES AND IMPLANTS; SUTURES; TISSUE ADHESIVES; etc., for hardness, strength, durability, safety, efficacy, and biocompatibility.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Electric Organ: In about 250 species of electric fishes, modified muscle fibers forming disklike multinucleate plates arranged in stacks like batteries in series and embedded in a gelatinous matrix. A large torpedo ray may have half a million plates. Muscles in different parts of the body may be modified, i.e., the trunk and tail in the electric eel, the hyobranchial apparatus in the electric ray, and extrinsic eye muscles in the stargazers. Powerful electric organs emit pulses in brief bursts several times a second. They serve to stun prey and ward off predators. A large torpedo ray can produce of shock of more than 200 volts, capable of stunning a human. (Storer et al., General Zoology, 6th ed, p672)Polyurethanes: A group of thermoplastic or thermosetting polymers containing polyisocyanate. They are used as ELASTOMERS, as coatings, as fibers and as foams.Urease: An enzyme that catalyzes the conversion of urea and water to carbon dioxide and ammonia. EC Acid: The reversibly oxidized form of ascorbic acid. It is the lactone of 2,3-DIKETOGULONIC ACID and has antiscorbutic activity in man on oral ingestion.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.Buffers: A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.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.Altitude: A vertical distance measured from a known level on the surface of a planet or other celestial body.Book Reviews as Topic: Critical analyses of books or other monographic works.Oxidative Stress: A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).Book ReviewsTibet: An autonomous region located in central Asia, within China.Altitude Sickness: Multiple symptoms associated with reduced oxygen at high ALTITUDE.Mountaineering: A sport involving mountain climbing techniques.Mythology: A body of stories, the origins of which may be unknown or forgotten, that serve to explain practices, beliefs, institutions or natural phenomena. Mythology includes legends and folk tales. It may refer to classical mythology or to a body of modern thought and modern life. (From Webster's 1st ed)Burns, ChemicalNorth CarolinaDiphtheria Toxin: An ADP-ribosylating polypeptide produced by CORYNEBACTERIUM DIPHTHERIAE that causes the signs and symptoms of DIPHTHERIA. It can be broken into two unequal domains: the smaller, catalytic A domain is the lethal moiety and contains MONO(ADP-RIBOSE) TRANSFERASES which transfers ADP RIBOSE to PEPTIDE ELONGATION FACTOR 2 thereby inhibiting protein synthesis; and the larger B domain that is needed for entry into cells.Diphtheria: A localized infection of mucous membranes or skin caused by toxigenic strains of CORYNEBACTERIUM DIPHTHERIAE. It is characterized by the presence of a pseudomembrane at the site of infection. DIPHTHERIA TOXIN, produced by C. diphtheriae, can cause myocarditis, polyneuritis, and other systemic toxic effects.Syringes: Instruments used for injecting or withdrawing fluids. (Stedman, 25th ed)Klebsiella pneumoniae: Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans.Respiratory Tract Infections: Invasion of the host RESPIRATORY SYSTEM by microorganisms, usually leading to pathological processes or diseases.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Klebsiella Infections: Infections with bacteria of the genus KLEBSIELLA.Enterobacter: Gram-negative gas-producing rods found in feces of humans and other animals, sewage, soil, water, and dairy products.Cephalosporins: A group of broad-spectrum antibiotics first isolated from the Mediterranean fungus ACREMONIUM. They contain the beta-lactam moiety thia-azabicyclo-octenecarboxylic acid also called 7-aminocephalosporanic acid.beta-Lactamases: Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.Pantothenic Acid: A butyryl-beta-alanine that can also be viewed as pantoic acid complexed with BETA ALANINE. It is incorporated into COENZYME A and protects cells against peroxidative damage by increasing the level of GLUTATHIONE.Niacin: A water-soluble vitamin of the B complex occurring in various animal and plant tissues. It is required by the body for the formation of coenzymes NAD and NADP. It has PELLAGRA-curative, vasodilating, and antilipemic properties.Riboflavin: Nutritional factor found in milk, eggs, malted barley, liver, kidney, heart, and leafy vegetables. The richest natural source is yeast. It occurs in the free form only in the retina of the eye, in whey, and in urine; its principal forms in tissues and cells are as FLAVIN MONONUCLEOTIDE and FLAVIN-ADENINE DINUCLEOTIDE.Thiamine: 3-((4-Amino-2-methyl-5-pyrimidinyl)methyl)-5-(2- hydroxyethyl)-4-methylthiazolium chloride.Vitamin B Complex: A group of water-soluble vitamins, some of which are COENZYMES.Niacinamide: An important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and PELLAGRA. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake.Cereals: Seeds from grasses (POACEAE) which are important in the diet.