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  • 1
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Offenes Foramen ovale ; Kontrastechokardiographie ; Neurochirurgie ; sitzende Position ; paradoxe Luftembolie ; Key words Patent foramen ovale ; Contrast echocardiography ; Neurosurgery ; Sitting position ; Paradoxical air embolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Background: The detection or ruling out of a patent foramen ovale (PFO) can be determined noninvasively by contrast echocardiography (CE). The transesophageal technique is superior to the transthoracic technique regarding sensitivity, whereas the specificity of both methods is equally high. This prospective study shows the rational use of transesophageal CE for the detection of a PFO, in patients without cardiovascular disorders. Methods: 165 patients (92 female, 73 male, age 48±18 years) with planned neuro-surgery in a sitting position, underwent CE to rule out a PFO. If the CE was positive, an alternative position was selected in order to avoid a paradoxical air embolism. Results: Initially, a transthoracic CE was performed in all patients resulting in 21 patients (13%) being positive and 39 patients (24%) being negative by sufficient image quality. A transesophageal CE was performed in 96 of the remaining 105 patients (63%). Here, further 25 patients showed a positive CE in the sense of a PFO. The combined use of transthoracic and transesophagel CE revealed a PFO in 46 of 165 patients (28%). Conclusion: The use of both, transthoracic and transesophageal CE is an efficient approach to the preoperative detection of a PFO in the sense of quality and economics. Depending upon the image quality, the use of a transesophageal examination could be avoided in one third of the cases.
    Notes: Zusammenfassung Die präoperative Kontrastechokardiographie (KE) wird zum Ausschluß eines offenen Foramen ovale (PFO) bei Patienten, die einer neurochirurgischen Intervention in sitzender Position unterzogen werden, eingesetzt. Die transösophageale (TEE) KE weist eine höhere Sensitivität in der Diagnostik eines PFO als die transthorakale (TTE) KE auf, während die Spezifität gleich hoch ist. Die Frage der vorliegenden prospektiven Studie war, in wie vielen Fällen die TEE-KE notwendig ist und von welchen Faktoren die Indikation beeinflußt wird. Patienten und Methodik: 165 Patienten (92 Frauen, 73 Männer, Alter 48±18 a) ohne kardiovaskuläre Erkrankungen, die einer neurochirurgischen Operation in sitzender Position unterzogen werden sollten, wurden einer präoperativen KE zum Ausschluß eines PFO zugeführt. Bei allen Patienten wurde zuerst eine TTE-KE durchgeführt. Bei einem positiven Ergebnis wurde auf eine TEE-KE verzichtet. Eine negative TTE-KE wurde lediglich akzeptiert, wenn eine ausreichende transthorakale Schallqualität vorhanden war. In allen anderen Fällen wurde eine TEE-KE angeschlossen. Ergebnisse: Die TTE-KE verlief bei 21 (13%) Patienten positiv und bei 39 (24%) negativ. Bei 105 (63%) mußte aufgrund der insuffizienten Schallqualität eine TEE-KE angeschlossen werden. Dabei wiesen weitere 25 Patienten ein PFO auf. Insgesamt wurden unter der kombinierten Anwendung der TTE-KE und TEE-KE bei 46 Patienten (28%) ein PFO diagnostiziert. In 30% der Fälle konnte auf eine TEE-KE verzichtet werden, wobei der limitierende Faktor der TTE-KE die mangelnde Schallqualität war. Schlußfolgerung: Bei der präoperativen KE zur Diagnostik eines PFO kann in Abhängigkeit von der transthorakalen Schallqualität in 30% auf eine TEE verzichtet werden. Durch einen rationalen Einsatz der TEE-KE können Kosten und unnötige Belastungen des Patienten vermieden werden.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Key wordsThauera ; Toluene ; Benzyl alcohol ; Toluene-oxidizing enzyme system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Toluene and related aromatic compounds can be mineralized to CO2 under anoxic conditions. Oxidation requires new dehydrogenase-type enzymes and water as oxygen source, as opposed to the aerobic enzymatic attack by oxygenases, which depends on molecular oxygen. We studied the anaerobic process in the denitrifying bacterium Thauera sp. strain K172. Toluene and a number of its fluoro-, chloro- and methyl-analogues were transformed to benzoate and the respective analogues by whole cells and by cell extracts. The transformation of xylene isomers to methylbenzoate isomers suggests that xylene degradation is similarly initiated by oxidation of one of the methyl groups. Toluene oxidation was strongly, but reversibly inhibited by benzyl alcohol. The in vitro oxidation of the methyl group was coupled to the reduction of nitrate, required glycerol for activity, and was inhibited by oxygen. Cells also contained benzyl alcohol dehydrogenase (NAD+), benzaldehyde dehydrogenase (NADP+), benzoate-CoA ligase (AMP-forming), and benzoyl-CoA reductase (dearomatizing). The toluene-oxidizing activity was induced when cells were grown anaerobically with toluene and also with benzyl alcohol or benzaldehyde, suggesting that benzyl alcohol or benzaldehyde acts as inducer. The other enzymes were similarly active in cells grown with toluene, benzyl alcohol, benzaldehyde, or benzoate. This is the first in vitro study of anaerobic oxidation of an aromatic hydrocarbon and of the whole-cell regulation of the toluene-oxidizing enzyme.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Key wordsThauera ; Toluene ; Benzyl alcohol ; Benzyl alcohol dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Toluene and related aromatic compounds are anaerobically degraded by the denitrifying bacterium Thauera sp. strain K172 via oxidation to benzoyl-CoA. The postulated initial step is methylhydroxylation of toluene to benzyl alcohol, which is either a free or enzyme-bound intermediate. Cells grown with toluene or benzyl alcohol contained benzyl alcohol dehydrogenase, which is possibly the second enzyme in the proposed pathway. The enzyme was purified from benzyl-alcohol-grown cells and characterized. It has many properties in common with benzyl alcohol dehydrogenase from Acinetobacter and Pseudo-monas species. The enzyme was active as a homotetramer of 160 kDa, with subunits of 40 kDa. It was NAD+-specific, had an alkaline pH optimum, and was inhibited by thiol-blocking agents. No evidence for a bound cofactor was obtained. Various benzyl alcohol analogues served as substrates, whereas non-aromatic alcohols were not oxidized. The N-terminal amino acid sequence indicates that the enzyme belongs to the class of long-chain Zn2+-dependent alcohol dehydrogenases, although it appears not to contain a metal ion that can be removed by complexing agents.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 168 (1997), S. 310-320 
    ISSN: 1432-072X
    Keywords: Key wordsThauera aromatica ; l-phenylalanine ; metabolism ; Phenylalanine transaminase ; Phenylpyruvate decarboxylase ; Phenylacetaldehyde ; dehydrogenase ; Phenylacetate-CoA ligase ; α-Oxidation ; of phenylacetyl-CoA ; Phenylglyoxylate:acceptor ; oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The anaerobic metabolism of phenylalanine was studied in the denitrifying bacterium Thauera aromatica, a member of the β-subclass of the Proteobacteria. Phenylalanine was completely oxidized and served as the sole source of cell carbon. Evidence is presented that degradation proceeds via benzoyl-CoA as the central aromatic intermediate; the aromatic ring-reducing enzyme benzoyl-CoA reductase was present in cells grown on phenylalanine. Intermediates in phenylalanine oxidation to benzoyl-CoA were phenylpyruvate, phenylacetaldehyde, phenylacetate, phenylacetyl-CoA, and phenylglyoxylate. The required enzymes were detected in extracts of cells grown with phenylalanine and nitrate. Oxidation of phenylalanine to benzoyl-CoA was catalyzed by phenylalanine transaminase, phenylpyruvate decarboxylase, phenylacetaldehyde dehydrogenase (NAD+), phenylacetate-CoA ligase (AMP-forming), enzyme(s) oxidizing phenylacetyl-CoA to phenylglyoxylate with nitrate, and phenylglyoxylate:acceptor oxidoreductase. The capacity for phenylalanine oxidation to phenylacetate was induced during growth with phenylalanine. Evidence is provided that α-oxidation of phenylacetyl-CoA is catalyzed by a membrane-bound enzyme. This is the first report on the complete anaerobic degradation of an aromatic amino acid and the regulation of this process.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-072X
    Keywords: Key wordsThauera aromatica ; Phenylacetyl-CoA ; α-Oxidation ; Phenylalanine ; Phenylacetyl-CoA:acceptor oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Anaerobic oxidation of phenylalanine and phenylacetate proceeds via α-oxidation of phenylacetyl-CoA to phenylglyoxylate. This four-electron oxidation system was studied in the denitrifying bacterium Thauera aromatica. It is membrane-bound and was solubilized with Triton X-100. The system used dichlorophenolindophenol as an artificial electron acceptor; a spectrophotometric assay was developed. No other products besides phenylglyoxylate and coenzyme A were observed. The enzyme was quite oxygen-insensitive and was inactivated by low concentrations of cyanide. Enzyme activity was induced under denitrifying conditions with phenylalanine and phenylacetate, it was low in cells grown with phenylglyoxylate, and it was virtually absent in cells grown with benzoate and nitrate or after aerobic growth with phenylacetate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Dordrecht, The Netherlands : Kluwer Academic Publishers
    International journal of cosmetic science 20 (1998), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The penetration of chemical reagents through human hair after bleaching has been spatially characterized using infrared microspectroscopy (IMS) with a synchrotron source. Chemical imaging of hair cross sections before and after bleaching was achieved with high contrast, using the peptide and lipid mid-infrared vibrational bands which are characteristic of hair. The ability to make images using functional groups as a contrast mechanism can be applied to studies of other chemical groups, if present, in the structure of the hair. As an example we show how the penetration of an organic active reagent in the hair structure can be quantified with a spatial resolution of few microns.These results demonstrate that synchrotron IMS is a powerful tool for characterizing chemical interactions of hair samples with specific cosmetic materials.〈section xml:id="abs1-2"〉〈title type="main"〉RésuméLa pénétration d'une molécule organique à l'intérieur de cheveux décolorés a été spatialement caractérisée par microspectroscopie infrarouge en utilisant une source de rayonnement synchrotron. Les images en contraste chimique de coupes microtomiques transversales de cheveux ont été obtenues avec un excellent contraste, en utilisant les bandes infrarouges des groupements peptides et lipidiques qui sont caractéristiques de sa structure. La possibilité d'obtenir des images en utilisant les différents groupements fonctionnels présents dans les spectres infrarouges permet d'étudier la répartition d'autres molécules chimiques si elles sont présentes en concentration suffisante dans la structure du cheveu. Cette caractéristique a été utilisée ici pour étudier la pénétration d'une molécule organique à travers la structure du cheveu avec une résolution latérale de quelques microns. Ces résultats démontrent la faisabilité de la microspectroscopie infrarouge par rayonnement synchrotron pour étudier spatialement les interactions entre le cheveu et des produits cosmétiques.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2952-2956 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single crystals of lithium niobate (LiNbO3) with y-cut orientation were irradiated at GANIL with 5.17 MeV/amu 155Gd ions at a fluence ranging from 1.5×1011 to 6.0×1011 ions cm−2. After irradiation the samples were implanted with europium ions of 70 keV energy at a fixed fluence of 5×1016 ions cm−2. Both irradiations and implantations were performed at room temperature. Thermal treatments in air, in the range 300–1100 °C, were applied to investigate the influence of the preirradiation damage on the thermal evolution of Eu implanted LiNbO3 crystals. Transmission electron microscopy micrographs exhibit the amorphous track formed by high-energy irradiations. Rutherford backscattering spectrometry results show that these amorphous tracks enhance the europium diffusion in depth of the LiNbO3. A diffusion coefficient and an activation energy were estimated to be about 4.2×10−15 cm2 s−1 and 0.42 eV, respectively. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An overview of the results obtained so far for the radiative I-mode regime on the upgraded Torus Experiment for Technology Oriented Research (TEXTOR-94) [Proceedings of the 16th IEEE Symposium on Fusion Engineering (Institute of Electrical and Electronics Engineers, Piscataway, NJ, 1995), Vol. 1, p. 470] is given. This regime is obtained under quasistationary conditions with edge neon seeding in a pumped limiter tokamak with circular cross section. It combines high confinement and high β (up to a normalized beta, βn=2) with low edge q values (down to qa=2.8) and high density even above the Greenwald limit together with dominant edge radiative heat exhaust, and therefore shows promise for the future of fusion research. Bulk and edge properties of these discharges are described, and a detailed account is given of the energy and particle confinement and their scaling. Energy confinement scales linearly with density as for the nonsaturated Ohmic Neo-Alcator scaling, but the usual degradation with total power remains. No deleterious effects of the neon seeding on fusion reactivity and plasma stability have been observed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 259-261 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-quality binary (Nd0.33Sm0.67)Ba2Cu3O7−δ monodomain superconductors were fabricated by the combination of a compositional-controlled melt-processing technique in air and postannealing in Ar. Critical current densities over the whole field range were observed strongly dependent on Ar postannealing while holding superconducting transition temperatures as high as 96 K. The suppressed chemical variation between the rare-earth element (RE: Nd, Sm) and Ba associated with disperse RE2BaCuOy (RE211) precipitate due to the decomposition occurring in Ar postannealing was attributed to the modified flux pinning. This makes Ar postannealing promising to process superconductors with desired properties for various applications. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4240-4242 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The superconducting transition and the magnetic structure of polycrystalline (HoxY1−x)Ni2B2C have been investigated for x≥0.75 by resistivity measurements and neutron diffraction, respectively. For HoNi2B2C, the well known antiferromagnetic structure with c- and a-axis components existing between 4.5 and 6 K has been confirmed. Whereas for all investigated samples the component having the a-axis modulated structure exists in a narrow temperature range only, the intensity connected to the spiral magnetic state along the c-axis increases for x=0.85 and x=0.75 monotonically as the temperature decreases to the lowest measuring temperature of 1.6 K. Our results strongly suggest that the incommensurate modulated structure along the a-axis is responsible for pair breaking in the investigated (HoxY1−x)Ni2B2C samples. On the other hand, the magnetic spiral structure with c-axis wave vector was found to coexist with superconductivity. A linear suppression of the superconducting transition temperature with increasing Ho content was observed which is in agreement with the Abrikosov–Gor'kov theory. We found a linear scaling with the effective de Gennes factors (x DG) (Ho) for both the superconducting transition and the magnetic ordering temperatures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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