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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 7 (1991), S. 2853-2859 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Annals of hematology 11 (1965), S. 267-283 
    ISSN: 1432-0584
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary 1. Working from observed data, the development of blood cell populations in vitro can be treated mathematically. 2. Two calculations result from the theory. The first permits preliminary calculation of cell distribution in definite periods of time if the number of cells at the beginning of the culture and a series of parameters (i. e., duration of mitosis, of interkinesis, of maturation, etc., of the individual stages of maturation) are known. 3. The second procedure, conversely, permits individual parameters to be ascertained from the results of two enumeration of cells in defined conditions. 4. Practical examples of both calculations are given. It emerges that the first procedure permits the adaption of the cultural conditions to the physiological relationships to be tested, whereas the second contributes to an understanding of the mode of action of growth and inhibitory substances, and also of irradiation on cell maturation. 5. Possible improvements and amplifications of the theory are discussed.
    Notes: Zusammenfassung 1. Ausgehend von den beobachteten Tatsachen gelingt es, die Entwicklung von Blutzellpopulationen in vitro in mathematischer Form zu behandeln. 2. Als Ergebnis der Theorie werden zwei Rechenverfahren erhalten, von denen das erste die Vorausberechnung der Zellverteilung für beliebige Zeiten erlaubt, wenn die Zellzahlen zu Beginn der Kultur und eine Reihe von Parametern (d. h. Mitosedauer, Interkinesedauer, Lebensdauer usw. der einzelnen Reifungsstadien) bekannt sind. 3. Das zweite Verfahren erlaubt umgekehrt unter bestimmten Voraussetzungen aus dem Ergebnis zweier Zellzählungen einzelne der Parameter zu ermitteln. 4. Für beide Rechenverfahren liegen praktische Beispiele vor. Es zeigt sich, daß das erste Verfahren die Anpassung der Kulturbedingungen and die physiologischen Verhältnisse zu prüfen erlaubt, während das zweite zur Aufklärung des Wirkungsmechanismus von Wuchs- und Hemmstoffen, sowie von Strahlen auf die Zellreifung beiträgt. 5. Die möglichen Verbesserungen und Erweiterungen der Theorie werden erörtert.
    Type of Medium: Electronic Resource
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 54 (1976), S. 141-143 
    ISSN: 1432-1440
    Keywords: PHLA ; Ethanol ; Acute Hyperlipoproteinemia ; PHLA ; Äthylalkohol ; Akute Hyperlipoproteinämie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die PHLA des Plasmas wurde bei 10 gesunden freiwilligen Versuchspersonen vor und während einer oralen Belastung mit 0,5 g Äthylalkohol/kg Körpergewicht als Initialdosis und 0,1 g Äthylalkohol/kg Körpergewicht und Stunde über 5 Stunden gemessen. Diese Äthanolbelastung führt zu einem Anstieg der Plasmatriglyceride auf etwa 170% des Ausgangswertes. Die PHLA des Plasmas wurde bestimmt vor, 15 Minuten, 1 und 5 Stunden nach Einnahme der Initialdosis. Sie änderte sich während der Alkoholbelastung gegenüber dem Ausgangswert wie gegenüber einer Kontrollserie mit Mineralwasser nicht signifikant. Dieser Befund wird verglichen mit früheren Untersuchungsergebnissen. Es wird die Schlußfolgerung gezogen, daß die akute äthanolinduzierte Hyperlipoproteinämie im gesunden Menschen vorwiegend durch eine Steigerung der Triglyceridsynthese in der Leber und Ausschleusung von VLDL und nicht durch eine verminderte Metabolisierung triglyceridreicher Lipoproteine bedingt zu sein scheint.
    Notes: Summary Post-heparin lipolytic-activity (PHLA) was studied in 10 healthy volunteers ingesting 0.5 g of ethanol/kg body weight initially and 0.1 g/kg body weight and hour over 5 hours. This dose led to enhancement in plasma triglycerides to about 170% of the pre-ethanol values. PHLA was determined before, 15 min, 1 and 5 hours after intake of the initial dose and showed no significant changes. These findings are compared with the results of earlier investigations. It is concluded that acute ethanol induced hyperlipoproteinemia in healthy man seems to be due mainly to enhanced hepatic synthesis of triglycerides and release of very low density lipoproteins and not to decreased catabolism of triglyceride rich lipoproteins.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 63 (1985), S. 90-92 
    ISSN: 1432-1440
    Keywords: Nicotine and metabolites ; Dose-response curves ; Blood pressure ; Heart rate ; Anaesthetized rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Blood pressure and heart rate in anaesthetized rats has been determined after i.v. injection of increasing doses of nicotine (NI) and its major metabolites, i.e. continine (CO), nornicotine (NOR), metanicotine (MN) and dihydrometanicotine (DMN). NI and MN elicited similar dose response curves, increasing blood pressure according to the dose injected. However, the dose response curve of MN was shifted to the right. Furthermore DMN caused similar pressor effects than MN and the pressor effects of NOR was even weaker. Only after injection of CO was a dose-dependent depressor effect observed and this was reversed after very high doses. CO also reduced heart rate in a dose-dependent manner, whereas NI and its other metabolites did not significantly change heart rate.
    Type of Medium: Electronic Resource
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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 148 (1987), S. 52-56 
    ISSN: 1432-072X
    Keywords: Methanogenic bacteria ; Sulfate-reducing bacteria ; Acetogenic bacteria ; Corrinoid ; Methane formation ; Cobalt ; Membrane cobamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Methanobacterium thermoautotrophicum a corrinoid-carrying membrane protein complex has been found, to which a tentative role in methane formation has been ascribed. To test this hypothesis representatives from different orders of methanogenic bacteria were examined for membrane-bound cobamides. These species differed in cell carbon precursor, in methane precursor, in occurrence of cytochromes and of the enzyme CO dehydrogenase, and in the systematic position (Methanobacteriales, Methanomicrobiales). All methanogenic bacteria contained cobamides in the membranes in amounts of about 60 nmol/g cell dry weight, in addition to different amounts of cobamides in the soluble cell fraction. The only central metabolic reaction obviously common to all of these methanogens was methyl coenzyme M reduction to CH4. It is concluded that the membrane corrinoid participates in this energy-conserving reaction. Sulfate-reducing and acetogenic bacteria were included in this survey. They contained different amounts of cobamides in the soluble cell fraction but not in the membrane, a possible exception being Acetobacterium woodii.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 120 (1979), S. 135-139 
    ISSN: 1432-072X
    Keywords: Carbon isotope discrimination ; Autotrophic CO2 fixation ; Methane formation ; Methanobacterium thermoautotrophicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fractionation of carbon isotopes by Methanobacterium thermoautotrophicum was studied during growth of the bacterium on H2 plus CO2 as sole carbon and energy sources. A 80% H2/20% CO2 gas mixture was continuously bubbled through the culture. At high gassing rates, in the absence of a “closed system effect”, cells and methane were found to be depleted in 13C relative to CO2 in the gas mixture by 2.4% and 3.4%, respectively. At low gassing rates, when more than 90% of the CO2 was converted to methane, the cells were enriched in 13C by 1.3% and methane was depleted in 13C by 0.5%; residual CO2 was enriched in 13C by 3.4%. The magnitude of isotope fractionation suggests that CO2 rather than bicarbonate is the active species of CO2 mainly utilized in both CO2 assimilation and CO2 reduction to methane. The apparent positive 13C-discrimination in cell carbon synthesis, which was observed at low gassing rates, indicates that most of the CO2 assimilated into cell material is not incorporated via reactions involved in CO2 reduction to methane.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-072X
    Keywords: Autotrophic growth ; Sulfate-reducing bacteria ; Carbon dioxide ; Hydrogen ; Formate ; Homoacetogenic bacteria ; Desulfobacterium autotrophicum ; Desulfovibrio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The capacity of mesophilic sulfate-reducing bacteria to grow lithoautotrophically with H2, sulfate and CO2 was investigated with enrichment cultures and isolated species. (a) Enrichments in liquid mineral media with H2, sulfate and CO2 consistently yielded mixed cultures of nonautotrophic, acetate-requiring Desulfovibrio species and autotrophic, acetate-producing Acetobacterium species (cell ratio approx. 20:1). (b) By direct dilution of mud samples in agar, various non-sporing sulfate reducers were isolated in pure cultures that did grow autotrophically. Two oval cell types (strains HRM2, HRM4) and one curved cell type (strain HRM6) from marine sediment were studied in detail. The strains grew in mineral medium supplemented only with vitamins (biotin, p-aminobenzoate, nicotinate). Carbon autotrophy was evident (i) from comparative growth experiments with non-autotrophic, acetate-requiring species, (ii) from high cell densities ruling out a cell synthesis from organic impurities in the mineral media, and (iii) by demonstrating that 96–99% of the cell carbon was derived from 14C-labelled CO2. Autotrophic growth occurred with a doubling time of 16–20 h at 24–28°C. Formate, fatty acids up to palmitate, ethanol, lactate, succinate, fumarate, malate and other organic acids were also used and completely oxidized. The three strains possessed cytochromes of the b-and c-type, but no desulfoviridin. Strain HRM2 is described as a new species of a new genus, Desulfobacterium autotrophicum. (c) The capacity for autotrophic growth was also tested with sulfate-reducing bacteria that originally had been isolated on organic substrates. The incompletely oxidizing, non-sporing types such as Desulfovibrio and Desulfobulbus species and Desulfomonas pigra were confirmed to be obligate heterotrophs that required acetate for growth with H2 and sulfate. In contrast, several of the completely oxidizing sulfate reducers were facultative autotrophs, such as Desulfosarcina variabilis, Desulfonema limicola, Desulfococcus niacini, and the newly isolated Desulfobacterium vacuolatum and Desulfobacter hydrogenophilus. The only incompletely oxidizing sulfate reducer that could grow autotrophically was the sporing Desulfotomaculum orientis, which obtained 96% of its cell carbon from 14C-labelled CO2. Desulfovibrio baarsii and Desulfococcus multivorans may also be regarded as types of facultative autotrophs; they could not oxidize H2, but grew on sulfate with formate as the only organic substrate.
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