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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract According to a recent proposal of a new council directive of the Commission of the European Community concerning the quality of water intended for human consumption, the maximum concentration of epichlorohydrin allowed in potable water is intended to be limited to 0.5 μg/L. To our knowledge no practical analytical technique for routine analysis purposes of aqueous samples is available at present. In this paper an analytical method is described using solid phase extraction (SPE) for the enrichment of epichlorohydrin from water samples with subsequent determination by gas-liquid chromatography with electron capture detection. Quantitative recovery was achieved. Using a sample volume of 100 mL a detection limit of 0.1 μg/L can be reached. The method has successfully been applied to the analysis of epichlorohydrin in tap water, surface water and waste water.
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  • 2
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Assistierte Spontanatmung ; Entwöhnung von der Beatmung ; Atemarbeit ; Key words Assisted spontaneous breathing ; Weaning from mechanical ventilation ; Work of breathing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Study objective: To investigate whether automatic tube compensation (ATC) or conventional pressure support (PS) is suit- able to compensate for the work of breathing imposed by the breathing circuit without altering the breathing pattern. Methods: Breathing pattern and work of breathing were measured in healthy volunteers. After a 20 min period of quiet breathing through a mouth piece (control) the volunteers were breathing through a 8.0 mm ID endotracheal tube (ETT) with four different settings: CPAP at 0 mbar, ATC, PS 5 mbar, PS 10 mbar. Each mode was applied for a 20 min period. At the end of each period data from 10 consecutive breaths were analyzed and aver-aged. Tidal volume (VT), breathing frequency (f), and minute ventilation (Ve) were determined from the stored gas flow tracings. Work of breathing was assessed as the pressure time product (PTP) calculated from the transdiaphragmatic pressure (Pdi) using a combined esophageal and gastric balloon catheter. Results: During the control period the breathing pattern was as follows: VT=882±277 ml, f=13,7±5/min, Ve=11,5±4,2 L/min. Maximal Pdi was 9,2±5,4 mbar and PTP was 11,3±7,1 mbar×s. Breathing CPAP through the ETT resulted in a slight increase in Pdi (10,8±5,4 mbar) and PTP (14,8±10,4 mbar×s) with an unchanged breathing pattern. How-ever, for the same amount of unloading from respiratory workload ATC did not alter the breathing pattern, whereas PS 5 mbar and PS 10 mbar resulted in a clear increase in VT (1014±202 ml, 1336±305 ml, respectively). Conclusion: From the presented data in healthy volunteers it might be concluded that ATC and PS 5 mbar and 10 mbar are suitable modes for unloading the respiratory system from work imposed by the breathing circuit. ATC does not alter the breathing pattern in contrast to PS which results in an increased tidal volume. Therefore, the exact compensa-tion of the work imposed by the ETT during ATC seems to be advantageous over ATC to assess the actual breathing pattern.
    Notes: Zusammenfassung Fragestellung: Ist die automatische Tubuskompensation (ATC) oder die konventionelle inspiratorische Druckunterstützung (pressure support, PS) geeignet, die zusätzliche, durch den endotrachealen Tubus und das Beatmungsgerät entstehende, Atemarbeit zu kompensieren? Methodik: In dieser Untersuchung an freiwilligen gesunden Probanden wurden die Atemarbeit und das Atemmuster gemessen. Nach einer Kontrollperiode mit Atmung über ein Mundstück atmeten die Probanden durch einen 8,0 mm Endotrachealtubus mit fünf verschiedenen Einstellungen: Kontinuierlich positiver Atemwegsdruck (CPAP) von 0 mbar, ATC während Inspiration, PS 5 mbar, PS 10 mbar. Jeder Modus wurde 20 min angewendet, bevor die Messung der Daten als Mittelwert von 10 konsekutiven Atemzügen vorgenommen wurde. Das Atemzugvolumen (VT), die Atemfrequenz (f) und das resultierende Atemminutenvolumen (Ve) wurden aus den gespeicherten Gasflußkurven bestimmt. Die Atemarbeit wurde als transdiaphragmaler Druck (Pdi) mit Hilfe eines Doppelballonkatheters im Magen und Ösophagus gemessen. Hiervon wurde das Druck-Zeit-Produkt (PTP) als Integral über die Inspirationszeit abgeleitet. Ergebnisse: Während der Kontrollphase betrugen VT=882±277 ml, f=13,7±5,0/min, so daß ein Ve von 11,5±4,2 l/min resultierte. Der maximale Pdi betrug im Mittel 9,2±5,4 mbar, das PTP 11,3±7,1 mbar×s. Bei Atmung durch einen endotrachealen Tubus ergaben sich ein leichter Anstieg des Pdi (10,8±5,4 mbar) und des PTP (14,8±10,4 mbar×s) bei relativ unverändertem Atemmuster. Während ATC zu einer Entlastung der Atemarbeit führte, ohne das Atemmuster zu beeinträchtigen, resultierten PS 5 mbar und PS 10 mbar in einer deutlichen Zunahme des VT auf 1014±202 ml bzw. 1336±305 ml bei einer vergleichbaren Abnahme der Atemarbeit. Schlußfolgerungen: Bei Probanden können sowohl ATC als auch PS zur Kompensation zusätzlicher Atemarbeit eingesetzt werden. Während das Atemmuster bei Anwendung von ATC dem der Spontanatmung ohne Tubus gleicht, führt PS zu einer deutlichen Erhöhung des Atemzugvolumens. Durch die gezielte Wegnahme lediglich der zusätzlichen Atemarbeit scheint ATC das bessere Verfahren zur Abschätzung des spontanen Atemmusters zu sein.
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  • 3
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
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  • 4
    ISSN: 1432-041X
    Keywords: Cell-ECM interactions ; Hydrozoa Vertebrates ; Xenografts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extracellular matrices (ECMs) of phylogenetically very distant organisms were tested for their ability to support cell adhesion, spreading and DNA replication in reciprocal xenograft adhesion tests. Mechanically dissociated cells of the medusa Podocoryne carnea (Cnidaria, Hydrozoa) were seeded on ECMs of polyps and medusa, and on several ECM glycoproteins or entire ECMs from vertebrates. In reciprocal experiments, cells from different vertebrate cell-lines were seeded on ECMs of polyps, medusae and also on electrophoresed and blotted extracts of both types of ECMs. The results demonstrate that medusa cells adhere and spread on polyp and medusa ECMs but do not recognize vertebrate ECMs or purified ECM glycoproteins. Vertebrate cells in contrast adhere, spread and proliferate on ECMs of polyps and medusae. The number of attached cells depends on the cell type, the type of ECM and, in certain cases, on the stage of the cell cycle. Cell adhesion experiments with pretreated ECMs of polyps and medusae, e.g. oxidation of carbohydrate residues with sodium-metaperiodate, or blocking of certain carbohydrate moieties with the lectin wheat germ agglutinin or a carbohydrate-specific monoclonal antibody, demonstrate that ECM carbohydrates are more important for cell-ECM interactions of medusa cells than for vertebrate cells. Furthermore, the experiments indicate that polyp and medusa ECMs contain different components which strongly modulate adhesion, spreading and DNA replication of vertebrate cells.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Anaesthesist 48 (1999), S. 485-503 
    ISSN: 1432-055X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Das endokrine System besteht aus einer Reihe von Einzelorganen oder Zellansammlungen wie zum Beispiel Schilddrüse, Nebenschilddrüse, Nebenniere, Genitalorgane oder Pankreas, die in über einen Steuerkreis mit negativen feed-back-Mechanismen Hormone in den Blutkreislauf sezernieren, die im wesentlichen für die Homöostase des Organismus verantwortlich sind. Diese Regelkreisläufe betreffen das physiologische Gleichgewicht hinsichtlich z.B. des Energiehaushaltes, des Elektrolyt- und Wasserhaushaltes sowie kardiovaskulärer und immunologischer Funktionen. Die innere Sekretion von Hormonen ist der wesentlicher Vermittler der Wirkung endokriner Organe, deren endokrine Aktivität sowohl durch einen hypothalamisch-hypophysären Regelmechanismus, als auch durch die Funktion anderer, synergistisch oder antagonistisch wirkender Hormone bestimmt wird. Die Wirkung der Hormone findet auf zellulärer Ebene statt (Abb. 1). Für die Anaesthesiologie hat das endokrine System eine besondere Bedeutung, da es im Rahmen einer Narkose und in Abhängigkeit von deren Qualität zu einer mehr oder weniger ausgeprägten Stimulation des Endokrinums infolge des Operationsstresses und der durch den Eingriff bedingten Schmerzen kommen kann. Über diese exogenen Faktoren, aber auch im Zusammenhang mit endogenen Regulations- oder Funktionsstörung bei Über- oder Unterfunktion einzelner endokriner Organe sind weitreichenden Störungen des Homöostase des menschlichen Organismus möglich. Über die daraus resultierende Dysfunktion weiterer Organ-systeme hat das endokrine System einen erhblichen Einfluß auf die perioperative Morbidität und Letalität. Dieser Artikel befaßt sich mit den anaesthesiologisch relevanten Aspekten der Dysfunktion endokriner Organe und auch der Besonderheiten der Narkose bei endokriner Tumore: Pankreas: Diabetes mellitus Schilddrüse: Hyper- und Hypothyreose, M. Basedow Nebenschilddrüse: Hyper- und Hypothyreoidismus Nebenniere: Phäochromozytom, Hyper- und Hypocortisolismus, Hyper- und Hypoaldosteronismus Tumore: Karzinoid Die verschiedenen endokrinen Erkrankungen haben bis auf wenige Ausnahmen nur geringe Bedeutung für die Wahl des Anaesthesieverfahrens. Sie fordern von dem Anaesthesisten eher eine genaue präoperativen Evaluation des Patienten mit dem Ziel einer präoperativen Stabilisierung, beziehungsweise die Kenntnis über mögliche intra- oder postoperativer Störungen der Homöostase aufgrund der endokrinen Dysregulation.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 164 (1995), S. 324-330 
    ISSN: 1432-072X
    Keywords: Key wordsEscherichia coli ; 6-Phosphogluconate ; dehydrogenase ; Ribulose-5-phosphate epimerase ; Ribose-5-phosphate isomerase ; Transketolase ; Transaldolase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pentose-phosphate pathway of Escherichia coli K-12, in addition to its role as a route for the breakdown of sugars such as glucose or pentoses, provides the cell with intermediates for the anabolism of amino acids, vitamins, nucleotides, and cell wall constituents. Through its oxidative branch, it is a major source of NADPH. The expression of the gene for NADP-dependent 6-phosphogluconate dehydrogenase (gnd) is regulated by the growth rate in E. coli. The recently identified gene for ribulose-5-phosphate 3-epimerase (rpe) is part of a large operon that comprises among others genes for the biosynthesis of aromatic amino acids. In recent years, genes for all enzymes of the pathway have been cloned and sequenced. Isoenzymes have been found for transketolase (genes tktA and tktB), ribose-5-phosphate isomerase (rpiA and rpiB) and transaldolase (talA and talB).
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  • 7
    ISSN: 1432-072X
    Keywords: Key words Glucose-fructose oxidoreductase ; Zymomonas mobilis ; Gfo-deficient mutant ; Sorbitol ; Protein export ; Signal sequence ; Periplasmic NADP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glucose-fructose oxidoreductase (GFOR) of the gram-negative bacterium Zymomonas mobilis is a periplasmic enzyme with the tightly bound cofactor NADP. The preprotein carries an unusually long N-terminal signal sequence of 52 amino acid residues. A sorbitol-negative mutant strain (ACM3963) was found to be deficient in GFOR activity and was used for the expression of plasmid-borne copies of the wild-type gfo gene or of alleles encoding alterations in the signal sequence of the pre-GFOR protein. Z. mobilis cells with the wild-type gfo allele translocated pre-GFOR, at least partially, via the Sec pathway since CCCP (carboxylcyanide-m-chlorophenylhydrazone; uncoupler of proton motive force) or sodium azide (inhibitor of SecA) abolished the processing of GFOR. A gfo allele with the hydrophobic region of the signal sequence removed (residues 32–46; Δ32–46) led to a protein that was no longer processed, but showed full enzymatic activity (180 U/mg) and had the cofactor NADP firmly bound. A deletion in the n-region of the signal sequence (residues 2–20; Δ2–20) or exchange of the entire GFOR signal sequence with the signal sequence of gluconolactonase of Z. mobilis led to active and processed GFOR. Strain ACM3963 could not grow in the presence of high sugar concentrations (1 M sucrose) unless sorbitol was added. The presence of the plasmid-borne gfo wild-type allele or of the Δ2–20 deletion led to the restoration of growth on media with 1 M sucrose, whereas the presence of the Δ32–46 deletion led to a growth behavior similar to that of strain ACM3963, with no sorbitol formation from sucrose.
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  • 8
    ISSN: 1432-072X
    Keywords: Key wordsZymomonas mobilis ; Metabolic flux ; analysis ; Sugar phosphates ; Glucose ; Fructose ; Xylose ; 13C-NMR ; In vivo 31P-NMR ; Rate-limiting step
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reasons for the well-known significantly different behaviour of the anaerobic, gram-negative, ethanologenic bacterium Zymomonas mobilis during growth on fructose (i.e. decreased growth and ethanol yields, increased by-product formation) as compared to that on its second natural substrate, glucose, have remained unexplained. A xylose-fermenting recombinant strain of Z. mobilis that was recently constructed in our laboratory also unexpectedly displayed an increased formation of by-products and a strongly reduced growth rate as compared to the parent strain. Therefore, a comprehensive study employing recently developed NMR-based methods for the in vivo analysis of intracellular phosphorylated pool sizes and metabolic fluxes was undertaken to enable a global characterization of the intracellular metabolic state of Z. mobilis during growth on 13C-labelled glucose, fructose and xylose in defined continuous cultures. The 13C-NMR flux analysis indicated that ribose 5-phosphate is synthesized via the nonoxidative pentose phosphate pathway in Z. mobilis, and it identified a metabolic bottleneck in the recombinant xylose-fermenting Z. mobilis strain at the level of heterologous xylulokinase. The 31P-NMR analyses revealed a global alteration of the levels of intracellular phosphorylated metabolites during growth on fructose as compared to that on glucose. The results suggest that this is primarily caused by an elevated concentration of intracellular fructose 6-phosphate.
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  • 9
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. The community structure of a benthic macroinvertebrate assemblage in a contaminated salt marsh was evaluated as part of an ecological characterization of a former chloralkali production facility in Georgia. Sample locations were chosen based on a gradient of the primary contaminants of concern, total mercury and polychlorinated biphenyls (PCBs), primarily Aroclor 1268. Sediment concentrations of Aroclor 1268 ranged from 2.3 to 150 mg/kg dry weight, while mercury concentrations ranged from 15 to 170 mg/kg dry weight in the study area. Mercury and PCBs were determined to be co-located in the sediments. Total organic carbon composition of the sediments was negatively associated with PCB and mercury concentrations. A total of 29 benthic taxa was identified in 49 samples; replicate samples were taken at each of five sampling locations. Mean infaunal density across all sampling locations was estimated at approximately 61,000 to 234,000 organisms m−2. Overall, polychaetes comprised 57% of the infaunal community with Manayunkia aestuarina as the dominant species. Oligochaetes, nematodes, crustacea, insects, and gastropods comprised 23.0, 18.0, 1.0, 0.7, and 0.2% of the overall benthic community, respectively. Density estimates of individual species between sampling locations showed no consistent patterns in response to pollutants. However, an analysis of higher taxonomic levels revealed some general trends. In uncontaminated areas, the benthic community was dominated by nematodes and oligochaetes, whereas moderate to highly contaminated areas were dominated by polychaetes and a smaller percentage of oligochaetes and nematodes. A trophic analysis of the same data set revealed that the community shifted from an evenly distributed percentage of surface and subsurface feeders in the uncontaminated areas to a community dominated by surface feeders in the more contaminated locations. Carnivores comprised from 0.13 to 0.90% of the trophic structure, with the percentage of carnivores generally decreasing with increasing contamination. Mercury and PCBs were bioaccumulating in representative marsh benthic invertebrates, presenting a potential source of contaminants to marsh consumers. Tissue PCB and tissue mercury concentrations were positively related to sediment PCB and mercury concentrations, respectively. A standard 14-day toxicity test using the amphipod Leptocheirus plumulosus showed no acute toxicity across the sampling locations.
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  • 10
    ISSN: 1433-8491
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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