Colitis: Inflammation of the COLON section of the large intestine (INTESTINE, LARGE), usually with symptoms such as DIARRHEA (often with blood and mucus), ABDOMINAL PAIN, and FEVER.Colitis, Ulcerative: Inflammation of the COLON that is predominantly confined to the MUCOSA. Its major symptoms include DIARRHEA, rectal BLEEDING, the passage of MUCUS, and ABDOMINAL PAIN.Colitis, Ischemic: Inflammation of the COLON due to colonic ISCHEMIA resulting from alterations in systemic circulation or local vasculature.Colitis, Microscopic: A condition characterized by chronic watery DIARRHEA of unknown origin, a normal COLONOSCOPY but abnormal histopathology on BIOPSY. This syndrome was first described in 1980 by Read and associates. Subtypes include COLLAGENOUS COLITIS and LYMPHOCYTIC COLITIS. Both have similar clinical symptoms and are distinguishable only by histology.Dextran Sulfate: Long-chain polymer of glucose containing 17-20% sulfur. It has been used as an anticoagulant and also has been shown to inhibit the binding of HIV-1 to CD4-POSITIVE T-LYMPHOCYTES. It is commonly used as both an experimental and clinical laboratory reagent and has been investigated for use as an antiviral agent, in the treatment of hypolipidemia, and for the prevention of free radical damage, among other applications.Colitis, Collagenous: A subtype of MICROSCOPIC COLITIS, characterized by chronic watery DIARRHEA of unknown origin, a normal COLONOSCOPY but abnormal histopathology on BIOPSY. Microscopic examination of biopsy samples taken from the COLON show larger-than-normal band of subepithelial COLLAGEN.Colon: The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.Trinitrobenzenesulfonic Acid: A reagent that is used to neutralize peptide terminal amino groups.Colitis, Lymphocytic: A subtype of MICROSCOPIC COLITIS, characterized by chronic watery DIARRHEA of unknown origin, a normal COLONOSCOPY but abnormal histopathology on BIOPSY. Microscopic examination of biopsy samples taken from the COLON show infiltration of LYMPHOCYTES in the superficial EPITHELIUM and the underlying connective tissue (lamina propria).Crohn Disease: A chronic transmural inflammation that may involve any part of the DIGESTIVE TRACT from MOUTH to ANUS, mostly found in the ILEUM, the CECUM, and the COLON. In Crohn disease, the inflammation, extending through the intestinal wall from the MUCOSA to the serosa, is characteristically asymmetric and segmental. Epithelioid GRANULOMAS may be seen in some patients.Intestinal Mucosa: Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.Inflammatory Bowel Diseases: Chronic, non-specific inflammation of the GASTROINTESTINAL TRACT. Etiology may be genetic or environmental. This term includes CROHN DISEASE and ULCERATIVE COLITIS.Mesalamine: An anti-inflammatory agent, structurally related to the SALICYLATES, which is active in INFLAMMATORY BOWEL DISEASE. It is considered to be the active moiety of SULPHASALAZINE. (From Martindale, The Extra Pharmacopoeia, 30th ed)Rectum: The distal segment of the LARGE INTESTINE, between the SIGMOID COLON and the ANAL CANAL.Sulfasalazine: A drug that is used in the management of inflammatory bowel diseases. Its activity is generally considered to lie in its metabolic breakdown product, 5-aminosalicylic acid (see MESALAMINE) released in the colon. (From Martindale, The Extra Pharmacopoeia, 30th ed, p907)Peroxidase: A hemeprotein from leukocytes. Deficiency of this enzyme leads to a hereditary disorder coupled with disseminated moniliasis. It catalyzes the conversion of a donor and peroxide to an oxidized donor and water. EC Agents: Drugs used for their effects on the gastrointestinal system, as to control gastric acidity, regulate gastrointestinal motility and water flow, and improve digestion.Colectomy: Excision of a portion of the colon or of the whole colon. (Dorland, 28th ed)Proctocolectomy, Restorative: A surgical procedure involving the excision of the COLON and RECTUM and the formation of an ILEOANAL RESERVOIR (pouch). In patients with intestinal diseases, such as ulcerative colitis, this procedure avoids the need for an OSTOMY by allowing for transanal defecation.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Colonoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the colon.Dysentery, Amebic: DYSENTERY caused by intestinal amebic infection, chiefly with ENTAMOEBA HISTOLYTICA. This condition may be associated with amebic infection of the LIVER and other distant sites.Ileostomy: Surgical creation of an external opening into the ILEUM for fecal diversion or drainage. This replacement for the RECTUM is usually created in patients with severe INFLAMMATORY BOWEL DISEASES. Loop (continent) or tube (incontinent) procedures are most often employed.Administration, Rectal: The insertion of drugs into the rectum, usually for confused or incompetent patients, like children, infants, and the very old or comatose.Enterocolitis, Pseudomembranous: An acute inflammation of the INTESTINAL MUCOSA that is characterized by the presence of pseudomembranes or plaques in the SMALL INTESTINE (pseudomembranous enteritis) and the LARGE INTESTINE (pseudomembranous colitis). It is commonly associated with antibiotic therapy and CLOSTRIDIUM DIFFICILE colonization.Pouchitis: Acute INFLAMMATION in the INTESTINAL MUCOSA of the continent ileal reservoir (or pouch) in patients who have undergone ILEOSTOMY and restorative proctocolectomy (PROCTOCOLECTOMY, RESTORATIVE).Mice, Inbred C57BLEnterocolitis: Inflammation of the MUCOSA of both the SMALL INTESTINE and the LARGE INTESTINE. Etiology includes ISCHEMIA, infections, allergic, and immune responses.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Diarrhea: An increased liquidity or decreased consistency of FECES, such as running stool. Fecal consistency is related to the ratio of water-holding capacity of insoluble solids to total water, rather than the amount of water present. Diarrhea is not hyperdefecation or increased fecal weight.Colonic Pouches: Sacs or reservoirs created to function in place of the COLON and/or RECTUM in patients who have undergone restorative proctocolectomy (PROCTOCOLECTOMY, RESTORATIVE).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)Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Probiotics: Live microbial DIETARY SUPPLEMENTS which beneficially affect the host animal by improving its intestinal microbial balance. Antibiotics and other related compounds are not included in this definition. In humans, lactobacilli are commonly used as probiotics, either as single species or in mixed culture with other bacteria. Other genera that have been used are bifidobacteria and streptococci. (J. Nutr. 1995;125:1401-12)Interleukin-10: A cytokine produced by a variety of cell types, including T-LYMPHOCYTES; MONOCYTES; DENDRITIC CELLS; and EPITHELIAL CELLS that exerts a variety of effects on immunoregulation and INFLAMMATION. Interleukin-10 combines with itself to form a homodimeric molecule that is the biologically active form of the protein.Cytokines: Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.Cecum: The blind sac or outpouching area of the LARGE INTESTINE that is below the entrance of the SMALL INTESTINE. It has a worm-like extension, the vermiform APPENDIX.Citrobacter rodentium: A species of gram-negative bacteria in the genus CITROBACTER, family ENTEROBACTERIACEAE. As an important pathogen of laboratory mice, it serves as a model for investigating epithelial hyperproliferation and tumor promotion. It was previously considered a strain of CITROBACTER FREUNDII.Ileitis: Inflammation of any segment of the ILEUM and the ILEOCECAL VALVE.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Helicobacter hepaticus: A species of HELICOBACTER that colonizes the CECUM and COLON of several strains of MICE, and is associated with HEPATITIS and carcinogenesis.Mice, Inbred BALB CAnti-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.Megacolon, Toxic: An acute form of MEGACOLON, severe pathological dilatation of the COLON. It is associated with clinical conditions such as ULCERATIVE COLITIS; CROHN DISEASE; AMEBIC DYSENTERY; or CLOSTRIDIUM ENTEROCOLITIS.Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Oxazolone: Immunologic adjuvant and sensitizing agent.Biopsy: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.Clostridium difficile: A common inhabitant of the colon flora in human infants and sometimes in adults. It produces a toxin that causes pseudomembranous enterocolitis (ENTEROCOLITIS, PSEUDOMEMBRANOUS) in patients receiving antibiotic therapy.Inflammation: A pathological process characterized by injury or destruction of tissues caused by a variety of cytologic and chemical reactions. It is usually manifested by typical signs of pain, heat, redness, swelling, and loss of function.Colon, Sigmoid: A segment of the COLON between the RECTUM and the descending colon.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)Sigmoidoscopy: Endoscopic examination, therapy or surgery of the sigmoid flexure.Colonic Diseases: Pathological processes in the COLON region of the large intestine (INTESTINE, LARGE).Proctitis: INFLAMMATION of the MUCOUS MEMBRANE of the RECTUM, the distal end of the large intestine (INTESTINE, LARGE).Intestine, Large: A segment of the LOWER GASTROINTESTINAL TRACT that includes the CECUM; the COLON; and the RECTUM.Cholangitis, Sclerosing: Chronic inflammatory disease of the BILIARY TRACT. It is characterized by fibrosis and hardening of the intrahepatic and extrahepatic biliary ductal systems leading to bile duct strictures, CHOLESTASIS, and eventual BILIARY CIRRHOSIS.Mucous Membrane: An EPITHELIUM with MUCUS-secreting cells, such as GOBLET CELLS. It forms the lining of many body cavities, such as the DIGESTIVE TRACT, the RESPIRATORY TRACT, and the reproductive tract. Mucosa, rich in blood and lymph vessels, comprises an inner epithelium, a middle layer (lamina propria) of loose CONNECTIVE TISSUE, and an outer layer (muscularis mucosae) of SMOOTH MUSCLE CELLS that separates the mucosa from submucosa.Azathioprine: An immunosuppressive agent used in combination with cyclophosphamide and hydroxychloroquine in the treatment of rheumatoid arthritis. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), this substance has been listed as a known carcinogen. (Merck Index, 11th ed)Colonic Neoplasms: Tumors or cancer of the COLON.Proctocolitis: Inflammation of the RECTUM and the distal portion of the COLON.Acute Disease: Disease having a short and relatively severe course.Prednisolone: A glucocorticoid with the general properties of the corticosteroids. It is the drug of choice for all conditions in which routine systemic corticosteroid therapy is indicated, except adrenal deficiency states.Tumor Necrosis Factor-alpha: Serum glycoprotein produced by activated MACROPHAGES and other mammalian MONONUCLEAR LEUKOCYTES. It has necrotizing activity against tumor cell lines and increases ability to reject tumor transplants. Also known as TNF-alpha, it is only 30% homologous to TNF-beta (LYMPHOTOXIN), but they share TNF RECEPTORS.Dinitrofluorobenzene: Irritants and reagents for labeling terminal amino acid groups.Gastrointestinal Hemorrhage: Bleeding in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Bacterial Translocation: The passage of viable bacteria from the GASTROINTESTINAL TRACT to extra-intestinal sites, such as the mesenteric lymph node complex, liver, spleen, kidney, and blood. Factors that promote bacterial translocation include overgrowth with gram-negative enteric bacilli, impaired host immune defenses, and injury to the INTESTINAL MUCOSA resulting in increased intestinal permeability. Bacterial translocation from the lung to the circulation is also possible and sometimes accompanies MECHANICAL VENTILATION.Mesentery: A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.Clostridium Infections: Infections with bacteria of the genus CLOSTRIDIUM.Collagen Diseases: Historically, a heterogeneous group of acute and chronic diseases, including rheumatoid arthritis, systemic lupus erythematosus, progressive systemic sclerosis, dermatomyositis, etc. This classification was based on the notion that "collagen" was equivalent to "connective tissue", but with the present recognition of the different types of collagen and the aggregates derived from them as distinct entities, the term "collagen diseases" now pertains exclusively to those inherited conditions in which the primary defect is at the gene level and affects collagen biosynthesis, post-translational modification, or extracellular processing directly. (From Cecil Textbook of Medicine, 19th ed, p1494)CD4-Positive T-Lymphocytes: A critical subpopulation of T-lymphocytes involved in the induction of most immunological functions. The HIV virus has selective tropism for the T4 cell which expresses the CD4 phenotypic marker, a receptor for HIV. In fact, the key element in the profound immunosuppression seen in HIV infection is the depletion of this subset of T-lymphocytes.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Ulcer: A lesion on the surface of the skin or a mucous surface, produced by the sloughing of inflammatory necrotic tissue.Mucin-2: A gel-forming mucin found predominantly in SMALL INTESTINE and variety of mucous membrane-containing organs. It provides a protective, lubricating barrier against particles and infectious agents.Administration, Oral: The giving of drugs, chemicals, or other substances by mouth.