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  • intestinal bacteria  (2)
  • Bronchoalveolar lavage  (1)
  • 1
    ISSN: 1436-6215
    Keywords: Acarbose ; hydrogen exhalation ; methane exhalation ; insulin ; gastric inhibitory polypeptide ; intestinal bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung An gesunden Probanden unter standardisierter, ballaststoffarmer Mischkost mit bzw. ohne Acarbose wurden kurz- und mittelfristige Einflüsse auf Toleranzerscheinungen mittels Bestimmung von Peptidhormonen und Atemgasmessungen untersucht. Wasserstoff und Methan wurden im Tagesprofil quantitativ bestimmt. Dabei bewirkte Acarbose infolge von Kohlenhydratvergärung im Dickdarm einen rund 20fachen Anstieg der Wasserstoffexhalation, die Methanexhalation änderte sich im Mittel nur wenig. Methanbildende Probanden exhalierten nach Stimulierung durch Acarbose signifikant weniger Wasserstoff als Personen ohne Methanbildung. Die unter Acarbose erniedrigten Glukose-, Insulin- und GIP- bzw. erhöhten Glukagonspiegel zeigen die verzögerte Glukoseresorption an und sind im regulatorischen Rahmen der Kohlenhydratassimilation verständlich. Im Laufe einer fünfwöchigen Acarboseeinnahme zusammen mit standardisierter Kost nahmen die aufgetretenen abdominellen Empfindungen wie z.B. Meteorismus deutlich ab, während die mikrobielle Kohlenhydratfermentation erhöht und die GIP-Sekretion erniedrigt blieben. Funktionelle Reaktionen des Gastrointestinaltrakts auf die durch Acarbose bewirkte veränderte Kohlenhydratzufuhr in das Colon wurden somit anhand von drei unabhängigen Parametern untersucht: anaerobe Gasproduktion, Freisetzung von Peptidhormonen und subjektive abdominelle Empfindungen. Die objektiven Parameter scheinen längerfristig konstant zu bleiben, während subjektive Parameter in dieser Zeit Anpassung zeigen.
    Notes: Summary Short and middle term effects of Acarbose were studied in volunteers on a standardized, low-fibre, mixed diet for the development of tolerance phenomena with gas exhalations and some peptide hormone levels as main parameters. Both hydrogen and methane were measured quantitatively as diurnal profiles. Acarbose caused an about 20-fold increase of H2 exhalation and had only moderate effects on methane production, indicating the presence of fermentable carbohydrates in the large bowel. Methanogenic individuals exhaled significantly less H2 than did nonmethanogenic subjects. Changes in blood glucose, serum insulin, GIP, gastrin, and plasma glucagon, caused by Acarbose, reflected delayed glucose absorption and were plausible within the regulatory framework of carbohydrate assimilation. When the Acarbose regime was maintained for 5 weeks on a controlled diet, abdominal sensations like e.g. meteorism declined remarkably while carbohydrate fermentation remained high and lowered GIP was sustained. Thus functional responses of the gastro-intestinal tract to altered carbohydrate supplies, elicited by Acarbose, were found by 3 independent parameters: anaerobic gas production, peptide hormone levels, and subjective abdominal sensations. The objective parameters seem to remain constant in the longer run, while subjective parameters show long-term adaptation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-6215
    Keywords: intestinal bacteria ; colonic microflora ; Acarbose ; anaerobic metabolization ; microorganisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Acarbose wurde mit einem künstlichen In-vitro-System auf Biotransformation durch lebensfähige intestinale Mikroflora geprüft, die aus den unteren Darmabschnitten von Probanden und Ratten stammte. Dazu wurde14C-Acarbose mit Darmkeimen, Nährstoffen und Spurenelementen inkubiert. Das Metabolitmuster von Acarbose setzt sich sowohl bei Menschen als auch bei der Ratte im wesentlichen aus Komponente 2, einem um Ring D ärmeren Homologen aus der Acarbose-Reihe, aus einem basischen Disaccharid, das aus den Ringen B und C des Ausgangsmoleküles besteht, und Komponente 1 zusammen. Letztere Verbindung entsteht durch spontane Umlagerung des nicht faßbaren Acarviosins (Ring A und B) in die trizyklische Verbindung mit Oxazolidin-Struktur. Acarviosin wird bei der Abspaltung von Ring C aus Komponente 2 gebildet. Das Metabolitmuster von Acarbose verändert sich durch eine mehrwöchige Einnahme dieser Substanz im Vergleich zum nicht adaptierten Menschen oder zur nicht adaptierten Ratte gravierend. Adaptierte intestinale Mikroflora liefert sowohl aus Acarbose als auch aus der trizyklischen Komponente 1 reichhaltigere Metabolitmuster. Neben den oben beschriebenen Produkten konnten methylierte, hexosylierte und n-butyrylierte Derivate von Acarbose und/oder Komponente 2 nachgewiesen werden.
    Notes: Summary The biotransformation of Acarbose (Bay g 5421) by an artificial in vitro system with viable intestinal microorganisms was investigated. The bacteria were obtained from the colon of man or from the caecum and colon of rats and were incubated anaerobically with14C-Acarbose in a nutrient solution. The metabolites were separated and purified by Chromatographic methods and identified by nuclear magnetic resonance (1H;13C) spectrometry and by mass spectrometry. Metabolites in man and rat are component 2 (minus the terminal glucose of Acarbose), a basic disaccharide consisting of rings B and C, and component 1. This latter substance is formed, after hydrolytic cleavage of the internal glucose of Acarbose, by spontaneous rearrangement of rings A and B (Acarviosine) into a tricyclic oxazolidine. The metabolite pattern of Acarbose is changed profoundly after several weeks of pretreatment of man or rat with this compound. The microflora adapted in such a manner yields in addition methylated, hexosylated, and n-butyroylated derivatives of Acarbose and/or component 2.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1335
    Keywords: Key words Lung cancer ; Oxidative stress ; Reactive oxygen species ; Radiotherapy ; Chemotherapy ; Vascular endothelial growth factor ; Bronchoalveolar lavage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Vascular endothelial growth factor (VEGF) is a potent inducer of physiological and neoplastic blood vessel growth. Moreover, in vitro studies have demonstrated that VEGF can be up-regulated by conditions associated with the generation of free radicals and reactive oxygen species. In a previous study we reported on strongly increased VEGF concentrations in the bronchoalveolar lavage fluid (BALF) of patients with lung cancer under therapy. In this study we aimed to reveal whether this increase was due to the therapy-associated intrapulmonary oxidative burden. Patients and methods: A total of 103 BALF samples from 94 patients with lung cancer (82 patients with non-small-cell lung cancer, 12 patients with small-cell lung cancer) were studied at different times before, during or after cancer treatment. VEGF levels in the lavage fluid and ratios of oxidised methionine in proteins of epithelial lining fluid (ELF) were determined. Results: As reported previously, strongly increased VEGF levels in the ELF were observed in patients undergoing chemotherapy when radiotherapy had been administered before. Increased levels of oxidised methionine indicated that these patients suffered from severe pulmonary oxidative stress that was significantly less in patients undergoing only chemotherapy. Similarly, VEGF concentrations in the ELF were significantly elevated in cancer patients at the time of diagnosis, but the oxidised methionine levels did not reveal significant oxidant/antioxidant imbalances in these patients. Conclusion: Systemic chemotherapy is associated with oxidative stress in vivo, which is more pronounced if patients are additionally treated with radiation. VEGF levels in the ELF are increased by this condition as well as by the activity of the tumour itself.
    Type of Medium: Electronic Resource
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