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  • 11
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In human subjects, apart from in the kidney, diamine oxidase occurs mainly in the gut. Therefore this enzyme can be used as an indicator of intestinal integrity. In biopsies of rectal mucosa the diamine oxidase activity was assayed in 55 patients, 41 having a histologically normal mucosa and 14 being diseased. The determinations of the enzymic activity were supervised by statistical quality control. In the unchanged rectal mucosa the diamine oxidase activity was 40 nmol/min×g on average. In 7 patients with rectal polyps the enzymic activity was significantly diminished in these benign tumours (x=7.7 nmol/min×g) apart from one, where it was elevated. A decrease in diamine oxidase activity was further observed in rectal carcinoma and ulcerative colitis. Whether the reduction of intestinal diamine oxidase activity accompanies premalignant or malignant states or whether it is a general sign of a disturbance of intestinal integrity remains questionable.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 12 (1982), S. 53-59 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The importance of intestinal diamine oxidase in histamine catabolism was proved in several series of experiments. However, intestinal monoamine oxidase might also be involved in histamine degradation either by direct deamination or by the deamination of methylated products. The soluble fraction of intestinal monoamine oxidase was purified and tested for its properties and substrate specificity by three different methods which are described in detail. Using 0.15M phosphate buffer the optimum pH was 7.4–7.6. TheK m values for serotonin and tyramine were 0.2 and 0.3×10−3 M. The most favoured substrates of the enzyme were tyramine, tryptamine and serotonin, but it was not pissible to classify the enzyme as a type A or B monoamine oxidase only by its substrate specificity. Histamine and ring methylated derivatives were not attacked by intestinal monoamine oxidase. This means that in the intestinal mucosa the oxidative pathway of histamine is completely catalysed by diamine oxidase.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 14 (1984), S. 351-355 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract N-methyl-N-formylhydrazine is the first active intermediate of the poison gyromitrin of the mushroom: false morel. This compound is a non-competitive inhibitor of human intestinal diamine oxidase (ID50=1.6×10−5 mol/l). This concentration corresponds to less than 5g of wet weight of mushroom/l. The diamine oxidases from 5 other sources are inhibited in a similar manner. Semicarbazide and aminoguanidine are 10-respectively 1000-fold more potent inhibitors of the human intestinal diamine oxidase. An involvement of the diamine oxidase inhibitory property ofN-methyl-N-formylhydrazine in toxic and mutagenic effects of the substance is considered.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 16 (1985), S. 102-104 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The diamine oxidase catalysed deamination of putrescine was reducedin vitro by histamine at concentrations occurring in the gut. An oral application of histamine, however, had no effect on the enzymic activity. When the histamine was injected i.p. a decrease of intestinal diamine oxidase activity was observed which, however, did not depend on histamine but probably on an unspecific irritation of the gut.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 20 (1987), S. 274-276 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In inflammatory diseases of the large bowel a reduced diamine oxidase activity was found which may be related to a reduced oxidative degradation of histamine. An experimental inhibition of diamine oxidase could therefore influence the large bowel histamine concentration. The diamine oxidase inhibitor aminoguanidine was administered to rats in a single dose of 100 mg/kg orally, i.v., or i.p. A rapid increase of the concentration of the drug in the large bowel was measured (half-life=2–5 h). During chronic amino-guanidine administration (3 times/week, 100 mg/kg orally) the large bowel histamine increased by 30% on average. This may be sufficient for a proliferative stimulus of the intestinal mucosa. Previous reports of an increase of body weight of animals and of patients under aminoguanidine treatment could not be confirmed by our study.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Histamine, among various “biologic-physiologic” abnormalities, is considered as a pathogenetic factor in chronic duodenal ulcer disease. The 10–30 per cent difference between its concentration in gastric and duodenal mucosa of patients compared to healthy controls, however, has to be demonstrated to be specific for the disease. It has to be shown to be neither a methodological artefact nor a common effect, concomitant factor or consequence. This study, after a series of pathogenetic trials examines systematic errors (biases) in the fluorometric-fluoroenzymatic histamine assay under the conditions of field studies including tests on specificity over a time period of 10 years. It concentrates on sensitivity (detection limits) and specificity of a standard technique described herein. A modified Shore procedure for large scale assays in human biopsies was developed including reference luminescence values for all reagents, cleaning material and glassware, reduction of OPD concentration to 0.05%, purification ofn-heptan, omission of centrifugation steps in the extraction procedure and use of 2 ml 1M HClO4 in the homogenization step to prevent losses of histamine due to adherence to the mechanical homogenizer. This assay was sensitive enough to measure histamine without difficulty in any biopsy taken. The detection limit was 3 ng/biopsy, but the smallest quantities of the amine ever obtained were 10.6 and 18.3 ng/biopsy (depending on both histamine content and biopsy weight). A series of problems had to be solved both in achieving and demonstrating specificity. It had to be defined not only for the assay in general, but also for assessing the difference in histamine content between ulcer patients and healthy controls. Exogenous more than endogenous fluorescing material interfering with the determination had to be excluded. A series of pitfalls were detected which had to be overcome in demonstrating the specificity of the assay by physicochemical and enzymatic tests. The specificity of the identification tests was more often impaired than the histmine assay itself. Fluorescing material interfering with the assay occurred in the homogenization, extraction and condensation steps, was found in water, OPD, the organic solvents, the cleaning material and in all kinds of plastic vessels. Plasticizers were shown by physicochemical characteristics including fluorescence spectra to be most likely responsible for this interfering material. Rules were developed to exclude such hazards in specificity in longterm pathobiochemical studies.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Inflammation research 18 (1986), S. 19-22 
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 18
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Conclusion The high potency of the small intestine to inactivate vasoactive biogenic amines is a combined effect of diamine and monoamine oxidase activity. Histamine, however, is specifically deaminated by diamine oxidase.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Following superior mesenteric artery occlusion and revasclarization in dogs all animals died in a circulatory collapse state. However, pretreatment by aminoguanidine, the strong and specific inhibitor of diamine oxidase, accelerated the circulatory break-down significantly and increased the venous plasma histamine concentrations up to levels which also in normal dogs are effective in the circulatory system. Furthermore, the haematocrit increased significantly more in the aminoguanidine-treated animals than in the dogs treated by saline. No changes in plasma diamine oxidase activity were observed in saline-treated animals during intestinal ischemia and following revascularization. In aminoguanidine-treated animals no enzymic activity could be measured. The results were interpreted by a protective role of intestinal diamine oxidase in intestinal ischemia. Enhancement of the enzymic activity in patients, for instance by heparin, may be helpful in mesenteric infarction disease.
    Materialart: Digitale Medien
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  • 20
    ISSN: 1420-908X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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