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  • 1990-1994  (1)
  • 1970-1974  (45,346)
  • 1972  (45,346)
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  • 101
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The basis for the difference between strains 168 (d-tyrosine-sensitive) and 23 (d-tyrosine-resistant) of Bacillus subtilis at the molecular level is that of transport of d-tyrosine into the cell. Strain 23 does not incorporate significant amounts of d-tyrosine into whole cells. A mutant derivative was isolated from strain 23 which had an altered transport system permitting d-tyrosine uptake, a change which also led to inhibition of growth by d-tyrosine. Strain 168 is extremely sensitive to growth inhibition caused by low concentrations of the d-isomer of tyrosine. A mutant derivative of strain 168 selected for its d-tyrosine resistant phenotype had an altered transport system which no longer recognized the d-isomer of tyrosine. These mutants define at least one element of the tyrosine transport system in B. subtilis and provide a convenient phenotype for the eventual location of the chromosal map position.
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  • 102
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four clostridial species (C. pasteurianum, C. butylicum, C. butyricum and C. tetanomorphum) grow on pyruvate. Two other species (C. roseum and C. rubrum) only ferment this compound; this is probably due to their inability to synthesize hexose phosphates from pyruvate (fructose-1,6-diphosphatase and pyruvate carboxylase are absent). The fermentation of pyruvate by the above clostridia yields acetate, carbon dioxide, hydrogen and small amounts of compounds more reduced than acetate. Hydrogen pressure increases the amount of ethanol, butanol and butyrate formed during the fermentation of pyruvate. Since C. roseum and C. rubrum contain a ferredoxin: NADP reductase it seems likely that NADPH2 is the coenzyme involved in ethanol formation. In accordance with this acetaldehyde and alcohol dehydrogenases exhibit activity with NADPH2. The glyceraldehyde-3-phosphate dehydrogenase of the clostridia under investigation is NAD specific and so is the β-hydroxy-butyryl-CoA dehydrogenase with the exception of C. kluyveri. The specific activity of hydrogenase and the coenzyme specificity of NAD(P) reductase vary among the clostridial species.
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  • 103
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary With growing cells of a Nocardia sp., isolated from soil, the degradation of 5-pregnene-3β, 20β-diol into 3-[5-oxo-7aβ-methyl-1β (1′β-hydroxo)-ethyl-3aα-perhydroindane-4α]-propionic acid was investigated. The results show that iron is essential for production of the perhydroindanpropionic acid, that this production is greatly enhanced by the presence of calcium and that it is maximal in the pH range 7.0–7.5.
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  • 104
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Es wurden Mutanten von Hydrogenomonas eutropha Stamm H 16 (ATCC 17699) isoliert, die weder auf Fructose noch auf Gluconat wachsen können. Alle Mutanten haben eine vollständig defekte KDPG-Aldolase. Die 6-PG-Dehydrase der Mutante F34 wird teilweise konstitutiv synthetisiert. Fructose induziert die übrigen Enzyme des Entner-Doudoroff-Abbauweges (Phosphoglucose-Isomerase und G-6-P-Dehydrogenase) nur wenig, während im Wildtyp der gesamte Enzymsatz voll induziert wird. 2. Gluconat unterdrückt das Wachstum von F 34 auf allen geprüften Substraten, einschließlich des autotrophen Wachstums. Fructose beeinflußt das Wachstum auf anderen Substraten nicht. 3. Auf Acetat oder Pyruvat wachsende Zellen von F 34 häufen intracellulär KDPG an. Die Pyruvat-Zellen scheiden KDPG in die Nährlösung aus. In Gegenwart von Gluconat erhöht sich die intracelluläre KDPG-Konzentration bis auf 89 μmole/g Trockengewicht; bis zu 270 μmole KDPG/g Trockengewicht werden innerhalb von 3 Std von den Zellen ausgeschieden. Fructose erhöht dagegen den KDPG-„pool” in den Zellen nicht wesentlich über den bereits vorhandenen Basiswert hinaus; sie wird anscheinend nur in sehr geringem Umfang in die Zellen aufgenommen. Dies mag auf einen zusätzlichen Defekt des Fructose-Transportsystems (pleiotroper Effekt) zurückzuführen sein. 4. Es wird gezeigt, daß Gluconat in auf Acetat wachsenden Zellen von F 34 den ATP-„pool” drastisch erniedrigt. Gleichzeitig sinkt der Wert der „energy charge” von 0,80 in Acetatzellen auf 0,68 nach Zugabe von Gluconat. Dabei wird auch die Gesamtkonzentration an Adeninnucleotiden stark verringert. Dieser Energieverlust der Zellen ist offenbar für die durch Gluconat verursachte Wachstumshemmung verantwortlich. Intracellulär angehäuftes KDPG wirkt nicht toxisch.
    Notes: Summary 1. Mutants of Hydrogenomonas eutropha strain H 16 (ATCC 17699) were isolated which are unable to grow both on fructose and on gluconate. Activity of 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase was not detectable in any mutant. Mutant strain F 34 was investigated in more detail. 6-phosphogluconate dehydrase is a partly constitutive enzyme in this mutant. In cells grown in the presence of fructose the enzymes of fructose degradation, phosphoglucose isomerase and glucose-6-phosphate dehydrogenase, are induced and formed up to a low level. 2. The growth of mutant F 34 is completely suppressed by gluconate on all substrates tested, growth under autotrophic conditions included. Fructose does not affect growth if utilizable substrates are available. 3. KDPG is intracellularly accumulated, when the cells of F 34 grow on acetate or pyruvate. Cells growing on pyruvate excrete KDPG into the medium. If gluconate is added simultaneously, the accumulation is increased up to an intracellular concentration of 89 μmoles KDPG/g dry weight. Up to 270 μmoles KDPG were excreted by 1 g cells (dry weight) within 3 h. Fructose does not significantly increase the KDPG-pool; the uptake of fructose is apparently very slow. This effect may be due to a defective fructose transport system (pleiotropic effect). 4. Measurements of the intracellular concentrations of adenine nucleotides (ATP, ADP, AMP) indicated that the ATP-pool is drastically decreased when cells of F 34 growing on acetate are supplied by gluconate. The energy charge of the cells decreases from 0.80 (in cells growing on acetate) to 0.68 after the addition of gluconate. The conversion of gluconate to KDPG acts apparently as an energy-sink. Surprisingly the total concentration of adenine nucleotides is decreased also. The inhibition of growth caused by gluconate is apparently due to the loss of energy and the decrease of the energy charge of the cells. The KDPG accumulated intracellularly does by itself not exert toxic effects.
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  • 105
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 87 (1972), S. 243-248 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die 15 verfügbaren Stämme von Chlorella vulgaris f. tertia Fott et Nováková (früher als Chlorella III, zwei auxotrophe Stämme als Chlorella VI, bezeichnet), die im Gegensatz zu Chlorella vulgaris Beijerinck Hydrogenase enthalten, wurden auf Thermophilie geprüft. Sie erwiesen sich sämtlich als thermophil und erreichen die obere Grenze des Wachstums bei 38–42°C. Damit erscheinen die beiden klassischen Hochtemperatur-Chlorellen (die Stämme 7-11-05 und 1-9-30 von Sorokin) als Angehörige eines ziemlich weit verbreiteten thermophilen Taxons. Unter den 19 verfügbaren Stämmen von Chlorella vulgaris wurden demgegenüber keine Hochtemperatur-Stämme gefunden. Auch bei C. homosphaera, C. fusca var. rubescens, C. luteoviridis, C. zofingiensis, C. sacharophila, C. minutissima und C. protothecoides konnten wir keine thermophilen Stämme nachweisen, während sich bei C. fusca und C. kessleri eine leichte Tendenz zur Thermophilie zeigte. Chlorella vulgaris f. tertia ist somit anscheinend ein Taxon ökologischer Spezialisten, die zu einer Existenz bei erhöhten Temperaturen, unter anaeroben Bedingungen oder auch als Symbionten in Tieren (zwei Stämme sind Zoochlorellen aus dem Süßwasser-Schwamm Spongilla) befähight sind. Wir nehmen an, daß es sich dabei um eine primitive, phylogenetisch alte Gruppe von Organismen handelt, aus der sich die morphologisch gleiche, typische Chlorella vulgaris durch den Verlust von Hydrogenase und Thermophilie entwickelt haben könnte.
    Notes: Summary The 15 available strains of Chlorella vulgaris f. tertia Fott et Nováková (previously designated as Chlorella III, two auxotrophic strains as Chlorella VI) contain hydrogenase, in contrast to Chlorella vulgaris Beijerinck. In addition, all strains of C. vulgaris f. tertia were now found to be thermophilic, i.e., able to grow at up to 38–42°C. Thus the two classical high-temperature Chlorellae (strains 7-11-05 and 1-9-30 of Sorokin) appear as members of a rather common thermophilic taxon. Among the 19 available strains of Chlorella vulgaris, by contrast, no hightemperature strains were observed. Likewise, we did not find any thermophilic strains of C. homosphaera, C. fusca var. rubescens, C. luteoviridis, C. zofingiensis, C. saccharophila, C. minutissima, and C. protothecoides. C. fusca and C. kessleri, on the other hand, show a slight tendency towards thermophily. Chlorella vulgaris f. tertia therefore seems to be a taxon of ecological specialists, equipped for the existence at elevated temperatures, in anaerobic environments, or as symbionts in animals (two strains are Zoochlorellae isolated from the fresh-water sponge, Spongilla). We assume that it represents a primitive, phylogenetically old group of organisms. The morphologically identical, typical Chlorella vulgaris might have evolved from it through loss of hydrogenase and thermophily.
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  • 106
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Merosporangia are initiated as simple evaginations of the ampulla wall. As merosporangia elongate, two new wall layers are deposited. Plasmalemmasomes are associated with developing walls of both ampullase and merosporangia. 2. Apical vesicles are present in merosporangia at all stages of elongation. Similar vesicles, and cisternae sometimes containing material having the same stainability as vesicle contents, are present in the ampulla. 3. In merosporangia in mid cleavage, the cleavage apparatus consists of furrows extending into the protoplast. Furrows are bounded by a membrane continuous with the ampulla plasmalemma and contain a lining layer of either granular or continuous appearance according to fixation. 4. Delimited spore protoplasts are bounded by a plasmalemma derived in part from the merosporangium plasmalemma and in part from cleavage furrow bounding membranes and are surrounded by an investing layer derived from the cleavage furrow lining. 5. The spore wall is laid down between the plasmalemma and the investing layer which thickens as the wall develops. 6. As sporangial heads mature, spores round off and spore walls thicken, the innermost layer of the ampulla wall and merosporangium wall is broken down, a new wall is formed internal to the ampulla wall and, in some heads, a cross wall is formed in the sporangiophore.
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  • 107
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 87 (1972), S. 303-322 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A facultative photo- and chemoheterotroph, the unicellular bluegreen alga Aphanocapsa 6714, dissimilates glucose with formation of CO2 as the only major product. A substantial fraction of the glucose consumed is assimilated and stored as polyglucose (probably glycogen). The oxidation of glucose proceeds through the pentose phosphate pathway. The first enzyme of this pathway, glucose-6-phosphate dehydrogenase, is partly inducible. In addition, the rate of glucose oxidation is controlled, at the level of glucose-6-phosphate dehydrogenase function, by the intracellular level of an intermediate of the Calvin cycle, ribulose-1,5-diphosphate, which is a specific allosteric inhibitor of this enzyme. As a consequence, the rate of glucose oxidation is greatly reduced by illumination, an effect reversed by the presence of DCMU, an inhibitor of photosystem II. Two obligate photoautotrophs, Synechococcus 6301 and Aphanocapsa 6308, produce CO2 from glucose at extremely low rates, although their levels of pentose pathway enzymes and of hexokinase are similar to those in Aphanocapsa 6714. Failure to grow with glucose appears to reflect the absence of an effective glucose permease. A general hypothesis concerning the primary pathways of carbon metabolism in blue-green algae is presented.
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  • 108
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Heterocysts reduce triphenyl tetrazolium chloride (TTC) faster than vegetative cells apparently because the absence of the O2-evolving photosystem II and the high electron transport activity in these cells. Although the rate of TTC reduction in vegetative cells is increased by the continuous removal of O2 evolved in photosynthesis, it has not been possible to obtain rates of TTC reduction comparable with those in heterocysts probably because of the continued competition for electrons between TTC and O2. The use of nitro-blue tetrazolium chloride (NBT) as a redox indicator has revealed the presence in filaments under aerobic conditions of a gradient of electron transport activity with strongest reducing power in the heterocysts, proheterocysts and vegetative cells next to heterocysts, and with gradually diminishing activity midway between two heterocysts. This pattern is indistinct in filaments grown under micro-aerophilic conditions. The strong electron transport activity in vegetative cells adjacent to heterocysts appears to promote reducing conditions in the heterocysts. Both, red-formazan formation in the heterocysts and blue-formazan deposition in vegetative cells greatly inhibit nitrogenase activity, and this was adversely affected also by the detachment of heterocysts from vegetative cells. The findings are consistent with the idea that the association of heterocysts with vegetative cells in essential for nitrogen fixation to occur in heterocystous blue-green algae.
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  • 109
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A strain of Achromobacter utilized 1-Naphthyl-N-methyl carbamate (Sevin, Carbaryl) as the sole source of carbon in salt medium. Four degradation products of sevin were identified to be 1-naphthol, hydroquinone, catechol and pyruvate. The organism grew on 1-naphthol, hydroquinone and catechol.
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  • 110
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 88 (1972), S. 87-96 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Several methods for the extraction of lipids from Candida yeast grown on n-alkanes were compared and evaluated. Special attention was paid to the completeness of extraction and to protect the unsaturated fractions from oxydation. 2. Significant alteration of the fatty acid composition during batch growth on hexadecane was observed. These changes make it necessary to harvest cells in a well defined state of the growing cell population. 3. If alkanes of chain length from C12 to C17 served as sole source of carbon fatty acids with corresponding chain length predominated. Even numbered alkane chains led to fatty acid profiles containing about 95% even numbered acids. Using odd numbered alkanes as substrates, the cells contained about 50% odd numbered fatty acids. 4. Cells grown on glucose and acetate media were also examined. Inhibition of de novo synthesis of fatty acids is stronger when the chain length of alkane substrates increases.
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  • 111
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le mécanisme d'assimilation des hydrocarbures par une levure, Candida lipolytica est étudié au moyen de l'analyse cinétique de la croissance du microorganisme et de la disparition du substrat hydrocarboné. Les hydrocarbures utilisés sont des n-paraffines. On ajoute au milieu soit un seul hydrocarbure (n-tetradécane ou n-hexadécane), soit un mélange binaire (n-dodécane et n-heptadécane), soit un mélange complexe (du n-undécane au n-octadécane). Contrairement à d'autres auteurs, nous pensons qu'il est peu probable que l'essentiel de la réaction s'effectue par contact des gouttes de substrat et des microorganismes puisque l'on observe des retards d'assimilation de certains hydrocarbures: ceux de faible poids moléculaire (les plus solubles) sont assimilés plus rapidement. Il semble donc que l'assimilation se fasse en grande partie à partir d'hydrocarbures préablement solubilisés.
    Notes: Summary The mechanism of hydrocarbon uptake by a yeast, Candida lipolytica has been studied by means of the kinetic analysis of micro-organism growth and substrate assimilation. Hydrocarbons used as only source of carbon are normal alkanes either pure (n-tetradecane or n-hexadecane) or in mixture of two paraffins (n-dodecane and n-heptadecane) or eight paraffins (n-undecane to n-octadecane). In these last cases delays in n-alkanes consumption are observed. They show that the most soluble substrates (lower molecular weight) are first consumed. In opposition to other authors we think that there is little probability for main reaction occurring by direct contact between drops and micro-organisms. The evidence indicates that n-alkanes are mainly utilized in the dissolved state.
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  • 112
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fatty acid composition of a recently isolated, extreme thermophilic bacterium of the genus Thermus has been determined and has been shown to be significantly different from that of Thermus aquaticus YT-1 when the two bacteria were grown under the same cultural conditions.
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  • 113
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 88 (1972), S. 153-161 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The existence of bristles, the hair-like appendages in several species of the genus Scenedesmus has been confirmed. The ultrastructure of bristles in Scenedesmus helveticus Arlet, Sc. acutus Meyen and Sc. acuminatus/Lagerh./Chodat has been studied by negative staining. While bristles of Sc. helveticus are composed of several microstrands with a regular pattern of cross-striation, the bristles of spineless species Sc. aculus and Sc. acuminatus seem to be composed only of individual microstrands. These investigations of bristles suggest their protein composition.
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  • 114
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Isocitrate lyase disappeared from acetate-adapted cells of Chlorella when cells were incubated in darkness with glucose. Loss of activity was particularly rapid in nitrogen-free medium and was accompanied by disappearance of the enzyme protein. 2. Loss of isocitrate lyase activity was prevented by addition of 2-deoxyglucose, glucosamine, cycloheximide or chloramphenicol. 3. The rate of loss of activity was increased by addition of 2:4-dinitrophenol but this substance prevented the loss of enzyme protein i.e it protected the inactivated enzyme from degradation. 4. In vitro studies on the digestion of isocitrate lyase protein by papain showed that the enzyme protein was protected from digestion by its substrate, isocitrate, but that inhibitors of the enzyme, namely phosphoenol pyruvate, succinate, oxaloacetate and pyruvate, provided no protection.
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  • 115
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 29 (1972), S. 51-58 
    ISSN: 1432-0738
    Keywords: Manganese ; Biliary Excretion of ; Manganese Bile Component ; Complexes ; Electron Paramagnetic Resonance Spectroscopy ; Mangan ; Ausscheidung mittels Galle ; Mangankomplexe mit ; Gallenkomponenten ; paramagnetische Elektronenresonanz-Spektroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird die Möglichkeit angedeutet, daß Mangan unmittelbar aus dem Blutplasma in die Galle der Ratten übergeht, was mit nachfolgender nichtenzymatischer Bildung von Komplexen mit Gallenkomponenten verbunden ist. Mangan könnte jedoch auch in die Galle in der Form von Komplexen mit Gallensäuren oder als N-enthaltende in der Leber gebildete Verbindungen ausgeschieden werden.
    Notes: Abstract The possibility of transfer of free Mn2+ cations directly from the blood plasma into the bile in rats followed by a nonenzymatic formation of complexes with the bile components was suggested. Mn2+ might be also excreted into the bile as a complex with bile acids or N-containing compounds formed in the liver.
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  • 116
    ISSN: 1432-0738
    Keywords: Hexane ; Quantitative Determination ; Gas Chromatography ; Blood ; Tissues ; Hexan ; quantitative Bestimmung ; Gaschromatographie ; Blut ; Organe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine Methode zur direkten gaschromatographischen Bestimmung kleiner Mengen leichtflüchtiger organischer Lösungsmittel (Hexan) in Blut und Organen wurde entwickelt. Blut konnte direkt, Organe nach Ultraschallhomogenisation in Wasser in den Gaschromatographen eingespritzt werden. Die direkte Einspritzung wurde durch die Verwendung eines speziellen Einlaßsystems mit auswechselbarem Filter, welcher die festen Blut- und Organbestandteile zurückhielt, ermöglicht. Der methodische Fehler wurde abgeschätzt und Reproduzierbarkeit experimentell bestimmt (7–10%).
    Notes: Abstract A method for the direct gas Chromatographic determination of small amounts of volatile organic solvents (hexane) in blood and tissues was developed. Blood was injected directly into a gas chromatograph, tissues were first homogenized in water by an ultrasonic technique. The direct injection was made possible by utilization of a special inlet system with exchangeable filter which retained nonvolatile components of blood and tissues. The methodical accuracy was estimated and the reproducibility was determined experimentally (7 to 10 %).
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  • 117
    ISSN: 1432-0738
    Keywords: Polychlorinated Biphenyls (PCB) ; Absorption and Distribution ; Environmental Contamination ; Toxicity ; Polychlorierte Biphenyle (PCB) ; Aufnahme und Verteilung ; Umweltverschmutzung ; Toxicität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach einmaliger Exposition männlicher Ratten mit Aerosolen eines technischen PCB-Gemisches aus niedrig chlorierten Biphenylen (Pydraul A 200, Monsanto) wurde die Resorption und Verteilung durch Messung der PCB-Konzentrationen in verschiedenen Organen untersucht. In Abhängigkeit von der Dauer der Aerosol-Exposition wird eine steile Zunahme der PCB-Konzentration in der Leber gefunden; sie beträgt bereits nach 15 min mehr als 50% des Maximalwertes, dem sich der Wert nach 2 Std mit 70 μg/g Gewebe nähert. Die Konzentration im Fettgewebe erreicht nach 30 min Expositionsdauer 14 μgPCB/g Gewebe, d.h. 27% der Konzentration in der Leber; im Gehirn liegt die Konzentration bei 9 μg/g Gewebe (=17% der Leberkonzentration). Messungen in Abhängigkeit von der Zeit nach der Aerosol-Applikation zeigen einen raschen Abfall der PCB-Konzentration in der Leber innerhalb eines Tages und eine Zunahme im Gehirn und Fettgewebe. Nach 2 Tagen sind die Hirn- und Leberkonzentrationen auf ein Minimum abgesunken, im Fettgewebe jedoch auf einen konstanten Maximalwert von 260 μg/g Gewebe angestiegen. Eine toxische Leberverfettung wurde unter diesen Versuchsbedingungen nicht gefunden. Mögliche Erklärungen der PCB-Akkumulation in der Leber und der Umverteilung in das Fettgewebe werden diskutiert.
    Notes: Abstract In male rats, after a single exposure to aerosol of a PCB-mixture of low chlorinated biphenyls (Pydraul A 200, Monsanto), absorption and distribution were studied by measurements of PCB concentration in different organs. By this method of inhalatory application a very good absorption is shown. Depending on durating of PCB exposure we observed a rapid increase of PCB concentration in liver; the concentration after 15 min was already more than 50% of maximum concentration attained after nearly 2 hours (70 μg/g tissue). Concentration in fat after 30 min of exposure is 14 μg/g tissue (about 27 % of liver concentration) whereas in brain tissue we found only 9 μg PCB/g tissue (=17% of liver concentration) at this time. Dependent on time passed after the end of aerosal application we measured a rapid increase of PCB concentration in liver during 24 hours, accompanied by an increase in levels in brain and fat. In the course of 2 days brain and liver concentration fall to a minimum value, whereas in fat a maximum is reached (260 μg/g tissue), which remains constant afterward. There was no toxic fatty degeneration of liver under these experimental conditions. Explanation of PCB accumulation in liver and distribution from organ to fat is discussed.
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  • 118
    ISSN: 1432-0738
    Keywords: Espartograss ; Acetylcholine ; Bronchoconstriction ; Dyspnea ; Occupational Hygiene ; Espartogras ; Acetylcholin ; Bronchokonstriktion ; Dyspnoe ; Gewerbehygiene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Inhalation von Staub des Espartograses führt bei Arbeitern, die mit diesem Material umgehen, zu dyspnoeischen Beschwerden. Wäßrige Extrakte von Espartogras wurden deshalb auf ihren Gehalt an glattmuskulär kontrahierenden Substanzen untersucht. Die Ergebnisse pharmakologischer Analysen der Extrakte am isolierten Meerschweinchenileum und chromatographischer Untersuchungen lassen annehmen, daß Espartogras Acetylcholin enthält, da die Extraktwirkung durch Atropin gehemmt, durch Inkubation mit Cholinesterase verringert und durch Physostigmin verstärkt und verlängert wird. Im Vergleich zu definierten Acetylcholinlösungen entspricht der Äquivalenzwert wäßriger Extrakte etwa 5μg Acetylcholin pro g Staub. Eine histaminfreisetzende Wirkung der Extrakte von Espartogras konnte bei Testung im Rattenabdomen nicht festgestellt werden. Histamin kommt als Ursache der glattmuskulären Kontraktionsaktivität in vitro nicht in Frage, da Mepyramin keinen Einfluß auf die Wirksamkeit der Extrakte hat. Es wird vermutet, daß die Dyspnoe von Espartoarbeitern hauptsächlich auf der Wirkung des im inhalierten Staub enthaltenen Acetylcholins beruht.
    Notes: Abstract Inhalation of espartograss dust produces dyspnea in workers handling this material. Therefore aqueous extracts from espartograss have been tested for presence of smooth muscle contracting substances. The results of pharmacological testing of the extracts in guinea pig ileum and of chromatographical studies lead to a supposition that espartograss contains acetylcholine because the extract action is inhibited by atropine, decreased by incubation with cholinesterase and increased as well as prolonged by physostigmine. Comparing the extract effects with known acetylcholine solutions the equivalent value of the aqueous extracts is about 5 μg acetylcholine per g dust. Espartograss extracts had no histamine liberating activity when tested in rat abdomen. Smooth muscle contraction cannot be attributed to the presence of histamine, as mepyramine had no influence on this action. It is therefore assumed that the dyspnea of espartoworkers is mainly caused by acetylcholine contained in the inhaled plant dust.
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  • 119
    ISSN: 1432-0738
    Keywords: Alcohol, Ethyl ; Injections, Intraperitoneal ; Hepatitis, Toxic ; Transaminases ; Glutamate Dehydrogenase ; Äthylalkohol ; Intraperitoneale Injektion ; Leberschädigung ; Transaminasen ; Glutamatdehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Männliche Wistarratten erhielten einmalig 4,8 g/kg Äthanol entweder per Schlundsonde in Form einer 10, 20, 40 bzw. 60 %igen (v/v) Mischung mit Aqua dest. oder intraperitoneal in Form einer 10, 20 bzw. 30%igen (v/v) Mischung mit 0,9%iger NaCl-Lösung. 4, 8 und 16 Std später wurden die Serumaktivitäten der GOT, GPT und GLDH sowie der Blutalkoholspiegel bestimmt. Sowohl nach oraler wie intraperitonealer Applikation bestand eine negative Korrelation zwischen der Konzentration der zugeführten Alkohollösungen und der Höhe der Blutalkoholspiegel. Nach oraler Gabe von Äthanol kam es in 4 der 12 Versuchsgruppen zu leichten Aktivitätserhöhungen der Transaminasen, während die Aktivität der GLDH im Serum nicht beeinflußt wurde. Die intraperitoneale Injektion von 4,8 g/kg Äthanol führte demgegenüber zu wesentlich stärkeren Aktivitätserhöhungen der Serumtransaminasen sowie auch zu einem Anstieg der GLDH. Dieser Aktivitätsanstieg der Serumfermente war am stärksten nach der Injektion der 30 %igen, am geringsten nach der Injektion der 10 %igen Alkohollösung, obwohl die applizierte Gesamtdosis an Alkohol die gleiche war. Die Bromsulfaleinprobe wurde durch intraperitoneal injizierten Alkohol jedoch nicht beeinträchtigt. Nach intraperitonealer Injektion von Äthanol traten entzündliche Reaktionen des Peritoneums auf, deren Ausmaß von der Konzentration der Lösungen abhing. Histologisch waren ausgedehnte Nekrosen des Leberparenchyms nachzuweisen; diese fanden sich ausschließlich subkapsulär an der Oberfläche der Leber, während die tiefer gelegenen Parenchymschichten lichtoptisch normal waren. Die besonders starke hepatotoxische Wirkung des Alkohols bei intraperitonealer Applikation beruht auf einer unspezifischen lokalen Schädigung der Leber. Für Untersuchungen zur Frage der generalisierten spezifisch-hepatotoxischen Wirkung des Alkohols ist die intraperitoneale Injektion somit ungeeignet.
    Notes: Abstract Male rats received ethanol in a single dose of 4.8 g/kg either by stomach tube as a 10, 20, 40 or 60 % (v/v) solution in distilled water, or by intraperitoneal injection as a 10, 20, or 30% (v/v) solution in saline. 4, 8 and 16 h later we determined serum enzyme activities of GOT, GPT and GLDH and blood alcohol levels. There was a negative correlation between the concentration of the ethanol solutions administered orally or intraperitoneally and blood levels of ethanol. Oral application of ethanol led to slight increments of serum transaminase activities in 4 out of 12 groups, but did not influence the activity of serum GLDH. Intraperitoneal injection of 4.8 g/kg ethanol, on the other hand, produced strong increments of serum transaminase activities, as well as an increase of serum GLDH. This increase of serum enzyme activities was highest after injection of the 30 % solution and smallest after injection of the 10% solution, though the total dose of ethanol was the same. Bromsulfalein clearance, however, was not impaired after intraperitoneal injection of ethanol. Intraperitoneal injection of the ethanol solutions led to peritoneal inflammation, the severity of which corresponded to the concentration of ethanol. Furthermore, extensive necroses of the liver occurred in the surface area of the liver, whereas the parenchyma underneath was free from light-optically detectable damage. The severe hepatotoxic action of ethanol when injected intraperitoneally is due to an unspecific local injury. Intraperitoneal injection, therefore, is no suitable method for investigation of the generalized specific hepatotoxic activity of ethanol.
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  • 120
    ISSN: 1432-0738
    Keywords: 2-Chloroethyl Isocyanate ; Generation of Vapour Atmospheres ; Inhalation Toxicity ; Threshold Limit Values ; orter: 2-Chloräthylisocyanat ; Erzeugung von Dampf-Luft-Gemischen ; Inhalationstoxicität ; Maximale Arbeitsplatzkonzentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die akute orale Toxicität von 2-Chloräthylisocyanat (CAIC) beträgt 396 mg/kg für männliche Ratten und 630 mg/kg für weibliche Mäuse. Am Kaninchenauge löste die außerordentlich geringe Menge von 5μl CAIC schwere Reizerscheinungen vor allem an der Conjunctiva aus. Auch die irritative Wirkung an der Kaninchenhaut war beträchtlich. In inhalationstoxikologischen Versuchen, deren Methodik durch Beschreibung eines einfachen Verfahrens zur Beladung von Luft ergänzt wurde, erwies sich CAIC als Reizgas ohne erkennbare systemischtoxische Wirkung. Die LC50 für Ratten beträgt bei sechsstündiger Exposition 6,3 ppm. In zwei subakuten Versuchen über 10 Tage mit Konzentrationen von 3,1 und 3,8 ppm überlebten alle Ratten. Zehn Tage nach Versuchsende wurden außer im Respirationstrakt (Tracheobronchitis. Bronchopneumonie) histologisch keine pathologischen Veränderungen gefunden. Es wird eine maximale Arbeitsplatzkonzentration (MAK) von 0,02 ppm vorgeschlagen.
    Notes: Abstract The acute oral toxioity of 2-chloroethyl isocyanate (CAIC) is 396 mg/kg for male rats and 630 mg/kg for female mice. The extremely small quantity of 5 μl CAIC caused severe irritation in the eyes of rabbits, particularly of the conjunctiva. The skin was also affected considerably. Inhalation experiments, involving a new version of a proven method for generating air-vapour mixtures, produced no evidence of systemic toxicity, but let CAIC be classified as an irritant vapour to the respiratory tract. The LC50 for rats is 6.3 ppm after exposure for 6 h, while rats in two experiments involving ten-day exposures to vapour concentrations of 3.1 and 3.8 ppm, respectively, survived. After a fortnight's withdrawal following each experiment, histological examinations showed tracheobronchitis and bronchopneumonia but no pathological change in any other organ examined. A threshold limit value (TLV) of 0.02 ppm is suggested.
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  • 121
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    Archives of toxicology 29 (1972), S. 107-115 
    ISSN: 1432-0738
    Keywords: Mercury ; Mercury in Urine, Blood and Biological Material ; Extraction and Photometric Determination ; Quecksilber ; Quecksilber im Harn, Blut und biologischen Material ; Extraktionsphotometrische Bestimmung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird eine extraktionsphotometrische Quecksilberbestimmung in biologischem Material beschrieben. Aufschluß mit Schwefelsäure-Perhydrol-Vanadin(IV)-oxidsulfat im Kochkolben unter Rückfluß. Zur Extraktion des Quecksilbers wird eine durch Ascorbinsäure stabilisierte benzolische Dithizonlösung. verwendet. Nach Maskierung der Fremdionen und Entfernung des Dithizonüberschusses wird die Orangefärbung des Quecksilberdithizonates bei 485 nm gegen einen aus dem selben Extrakt hergestellten Blindwert gemessen. Die benzolische Quecksilberdithizonatlösung ist nicht lichtsensibel. Die Quecksilberbestimmung ist in Harn, Blut, Leber- und Nierengewebe, Fisch, Eiern, Getreidekörnern und Pflanzen möglich. Die Methode ist als Schnellbestimmung im Harn für das chemischdiagnostische und toxikologische Routinelaboratorium geeignet.
    Notes: Abstract An extractive and photometric determination of mercury in biological material is described. Wet digestion with sulfuric acid — perhydrol — vanadium IV oxidesulfate under reflux. A solution of dithizone in benzene, stabilized with ascorbic acid, is used as an extractant for mercury. After removing the excess of dithizone and masking the interfering ions, the orange colored mercury dithizonate is measured against a blank made from the same extract. The benzene solution of the mercury dithizonate is not light sensible. The determination of mercury is possible in urine, blood, liver and kidney tissue, fish, eggs, cereals and plants. The method is useful as a rapid determination in urine for the routine chemical-diagnostic and toxicologic laboratory.
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  • 122
    ISSN: 1432-0738
    Keywords: AN 1 ; Amphetamine ; Doping Controls ; AN 1 ; Amphetamin ; Dopingkontrollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Nach Einnahme von AN 1 (1) (α-Phenyl-α-N-(1-phenyl-isopropyl)-amino-acetonitril) konnte im Urin von Versuchspersonen mit Hilfe der Kombination GC-MS Amphetamin (2) nachgewiesen werden. Da dieses Psychotonikum frei im Handel erhältlich ist, sollte dieser Befund in Zukunft bei der Durchführung von Dopingkontrollen berücksichtigt werden.
    Notes: Abstract After oral administration of the psychotonic AN 1 (1) (α-Phenyl-α-N-(1-phenylisopropyl)-amino-acetonitril), amphetamine (2) could be detected in the urine of volunteers by GC-MS-analysis. Since this drug is commercially free available this finding should be considered in doping controls in the future.
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  • 123
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    Archives of toxicology 29 (1972), S. 171-188 
    ISSN: 1432-0738
    Keywords: Trichloroethylene ; Trichloroethanol ; Trichloroacetic Acid ; Chloral Hydrate ; Trichloräthylen ; Trichloräthanol ; Trichloressigsäure ; Chloralhydrat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Drei Gruppen von je 5 bis 6 freiwilligen Versuchspersonen inhalierten analytisch kontrollierte Trichloräthylenkonzentrationen, 6 Std täglich an 5 aufeinanderfolgenden Wochentagen, in den Versuchsserien: (a) 50 ppm gleichbleibend; (b) 250 ppm 12 min/Std (hohe Spitzenkonzentrationen beim Durchschnitt von 50 ppm); und (c) 100 ppm gleichbleibend. Die Trichloräthanol-(TCE)Spiegel im Blut wurden 3mal täglich, die TCE und Trichloressigsäure-(TCA)Gehalte im Harn 2mal täglich gaschromatographisch (TCE) bzw. colorimetrisch (TCA) bestimmt. TCE akkumuliert im Blut von Tag zu Tag auf Endwerte von (a) 2,0 μg/ml, (b) 2,5 μg/ml oder (c) 5,0 μg/ml; die Halbwertzeit für TCE im Blut beträgt stets 12 Std. Nach einmaliger Einnahme von 15 mg/kg Chloralhydrat (normale hypnotische Dosis) erreichte TCE im Blut in 1 Std ca. 7 μg/ml, die Eliminationscharakteristik ist mit derjenigen nach Tri-Inhalation identisch. Der nach 100 ppm Tri erreichte TCE-Maximalwert entspricht dem bei Chloralhydrateinnahme in 2 bis 2 1/2 Std erreichten. Solche TCE-Spiegel sind nach Literaturangaben in Vigilanztests leistungsmindernd. Die Bildung und Akkumulation von TCE ist wahrscheinlich die Ursache des „psycho-organischen Syndroms”, das bei in Tri-Atmosphäre beschäftigten Arbeitern beobachtet wird. Die Ausscheidung von TCE und TCA im Harn bei mehrtägigei Tri-Inhalation folgt nicht Gesetzmäßigkeiten, die aus Einzelversuchen (etwa 6 Std-Inhalationen) abgeleitet werden können. Die bisher in der Literatur beschriebenen Verfahren zur Berechnung der Tri-Exposition aus den TCE und/oder TCA-Ausscheidungen bedürfen daher der Revision.
    Notes: Abstract Groups of 5 to 6 volunteers each participated in three experimental series involving inhalation of analytically controlled trichloroethylene concentrations for 6 h daily on 5 successive week days: (a) 50 ppm constant, (b) 250 ppm for 12min/h (high peak concentrations, average 50 ppm); (c) 100 ppm constant. The trichloroethanol (TCE) levels in the blood were determined 3 times daily, the TCE and trichloroacetic acid (TCA) levels in the urine twice daily by means of gas Chromatographic (TCE) and colorimetric (TCA) techniques. It was seen that TCE accumulates in the blood from day to day reaching maximum values of (a) 2.0 μg/ml, (b) 2.5 μg/ml, or (c) 5.0 μg/ml; the half life of TCE in the blood was 12 h in each case. After a single dose of 15 mg/kg chloral hydrate (normal hypnotic dose) TCE reached levels of approx. 7 μg/ml within 1 h; the pattern of elimination was identical to that obtained after Tri inhalation. The maximum TCE value after 100 ppm Tri coincides with that obtained 2 to 2 1/2 h after ingestion of chloral hydrate. There are some data in the literature indicating that such TCE levels reduce the performance ability in vigilance tests. The formation and accumulation of TCE probably is responsible for the “psycho-organic syndrome” encountered during occupational exposure to Tri. On inhalation of Tri for several days the urinary excretion of TCE and TCA does not follow certain rules which may be derived from single experiments (for instance, 6 h-inhalations). It would appear, therefore, that the procedures described in the literature for assessment of Tri exposure on the basis of TCE and/or TCA excretion are subject to revision.
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  • 124
    ISSN: 1432-0738
    Keywords: Hashish ; Detection ; Thin Layer Chromatography ; Haschisch-Nachweis ; Dünnschichtchromatographie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die drei wichtigen Inhaltsstoffe von Haschisch, Cannabidiol, Tetrahydrocannabinol und Cannabinol, lassen sich auf vier verschiedenen Kieselgel-Fertigplatten nach Entwicklung mit Toluol und Besprühen mit 0,1% wäßriger Lösung von Fastblue B voneinander trennen. Eine Vorbehandlung der Platten mit Diäthylamin ist erforderlich. Die einzelnen Rf-Werte werden angegeben.
    Notes: Abstract The three major constituents of hashish, cannabidiol, tetra-hydrocannabinol and cannabinol, can be separated on four different commercial precoated silica gel sheets after development in toluene and spraying with 0,1% aqueous Fastblue B. A pretreatment of the sheets with diethylamine is necessary. The individual RF-values are recorded.
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  • 125
    ISSN: 1432-0738
    Keywords: Phalloidin Toxicity ; Hepatic Damage ; Partial Hepatectomy ; Phalloidin Toxizität ; Leberschädigung ; Partielle Leberresektion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Partielle Leberresektion, die 1, 3, 4 oder 5 Tage vor i. p. Injektion von Phalloidin durchgeführt wird, verhindert in Ratten die durch diesen Stoff bedingte Leberschädigung und Mortalität.
    Notes: Abstract In rats, the hepatic injury and mortality elicited by an intraperitoneal injection of phalloidin are prevented by partial hepatectomy performed 1, 3, 4 or 5 days earlier.
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  • 126
    ISSN: 1432-0738
    Keywords: Organophosphorus Poisoning ; Acetylcholinesterase ; Dogs Brain ; Organophosphatvergiftung ; Acetylcholinesterase ; Hundegehirn
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In 27 Arealen des Hundegehirns wurde die Aktivität der Acetylcholinesterase nach i.v.-Infusion von O-Aethyl-S-(2-dimethylaminoaethyl)-methylphosphonothioat (20.0 μg/kg innerhalb 10 min) gemessen. In allen untersuchten Hirnpartien war die AChE-Aktivität signifikant vermindert; die stärkste Hemmung wurde in den Kernen des Nervus vagus und hypoglossus sowie im Colliculus superior beobachtet.
    Notes: Abstract Acetylcholinesterase activity in 27 areas of the dog brain was studied after i.v. infusion of O-ethyl-S-(2-dimethyl-aminoethyl) methylphosphonothioate, administered 20.0 μg/kg per 10 min. This activity was significantly decreased in all brain parts studied; the greatest decrease was observed in the nucleus nervi vagi, hypoglossi and in the colliculus superior.
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  • 127
    ISSN: 1432-0738
    Keywords: Specific and Non-Specific Cholinesterases ; Guinea Pig Tissues ; Diisopropylfluorophosphate ; Obidoxime ; Reactivation ; Ageing ; Spezifische und unspezifische Cholinesterasen ; Meerschweinchengewebe ; Diisopropylfluorophosphat ; Obidoxim ; Reaktivierung ; Alterung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird über Versuche berichtet, die Cholinesterasen von Erythrocyten und Plasma und von Homogenaten aus Großhirn und Herzventrikel des Meerschweinchens als spezifische oder unspezifische Cholinesterasen (ChEs) zu charakterisieren. Der relative Gehalt an spezifischen und unspezifischen ChEs kann durch die Verwendung der Substrate Acetylcholin, Acetyl-/gb-methylcholin und Buturyleholin annäherungsweise ermittelt werden. Der Gehalt an unspezifischen ChEs sinkt in der Reihenfolge Plasma, Herzventrikel, Großhirn. Bei der Bestimmung der Inaktivierung, Reaktivierung und Alterungsgeschwindigkeit der verschiedenen ChEs lassen sich folgende Unterschiede nachweisen: 1. Die spezifischen ChEs von Erythrocyten und Großhirn werden durch Obidoxim verschieden stark gehemmt. 2. Die unspezifischen ChEs von Plasma und Herzventrikel können gegenüber denen des Großhirns durch ihre verschiedenen k2-Werte hei der Inaktivierung mit DFP eindeutig unterschieden werden. 3. Gemessen an der Reaktivierbarkeit mit Obidoxim altert die DFP-inaktivierte spezifische ChE des Großhirns langsamer als die der Erythrocyten. 4. Die Reaktivierbarkeit der phosphorylierten unspezifischen ChEs in Plasma, Herzventrikel und Großhirn und ihre Alterungs-Halbwertszeiten hängen von der verwendeten Obidoximkonzentration ab.
    Notes: Abstract Studies were made to characterize the cholinesterases from erythrocytes, plasma and homogenates of cardiac ventricular muscle and brain of guinea pigs as specific or non-specific cholinesterases (ChEs). The relative content of both can be estimated using the substrates acetylcholine, acetyl-β-methylcholine and butyrylcholine. The content of non-specific ChE was found to decrease in the sequence: plasma cardiac-ventricular-muscle brain. The inactivation, reactivation and ageing-rate of the various ChEs were determined and yielded the following differences: 1. The specific ChEs from erythrocytes and brain were inhibited to different degrees by obidoxime. 2. The non-specific ChEs from plasma and cardiac ventricular muscle could be clearly differentiated from that of brain by means of their different k2-values upon inactivation with DFP. 3. The specific ChE of brain once inactivated by DFP was found to age more slowly than that of erythrocytes, taking the reactivation by obidoxime as indicator. 4. The reactivation of the phosphorylated non-specific ChEs and the half-life of the ageing processes were found to be dependent on the obidoxime concentration used.
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  • 128
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    Archives of toxicology 29 (1972), S. 267-278 
    ISSN: 1432-0738
    Keywords: Phosgene Poising ; Antiserum ; Prevention ; Treatment ; Anaphylaxis ; Active Immunization ; Phosgen ; Vergiftung ; Antiserum ; Vorbeugung ; Therapie ; Anaphylaxie ; Aktive Immunisierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Man kann einer Phosgen-Vergiftung durch Antiserum-Injektion vor der Vergiftung vorbeugen. Man kann eine Phosgen-Vergiftung durch Antiserum-Injektion nach der Vergiftung heilen. Immunisierung gegen Phosgen-Vergiftung ist möglich durch Injektionen mit Extrakt von mit Phosgen behandelten Lungen. Die Immunität dauert bis zu 60 Tagen. Ein anaphylaktischer Schock wurde beobachtet, wenn das Antiserum vor oder nach der Phosgen-Vergiftung injiziert wurde. Es empfiehlt sich eine große Dosis Antiserum einzuspritzen, um einem anaphylaktischen Schock vorzubeugen.
    Notes: Abstract Phosgene poisoning can be prevented by injection of antiserum prior to phosgene poisoning. Phosgene poisoning can be treated by injection of antiserum following phosgene poisoning. Immunization against phosgene poisoning is obtained by injection of extract of lung treated with phosgene. The immunity is long lasting (60 days). An anaphylactic shock is observed when antiserum is injected either before or after phosgene poisoning. For the prevention of anaphylactic shock a high dose of serum is recommended.
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  • 129
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    Archives of toxicology 30 (1972), S. 75-85 
    ISSN: 1432-0738
    Keywords: Dichlorvos ; Human Lymphocytes ; Chromosome Aberrations ; Cytogenetics ; Chromosome Degeneration ; Dichlorvos ; Menschliche Lymphocyten ; Chromosomen-aberrationen ; Cytogenetik ; Cytotoxizität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Dichlorvos (2,2-Dichlorvinyl-dimethylphosphat) wurde in spezifischen Abständen zu Kulturen menschlicher Lymphocyten bis zu Konzentrationen von 1 bis 40 μg/ml hinzugegeben. Die nachfolgenden Untersuchungen ergaben, daß Dichlorvos in Konzentrationen von 5 bis 40 μg/ml cytotoxisch wirkte, aber keine spezifischen cytogenetischen Veränderungen bewirkte.
    Notes: Abstract Dichlorvos (2,2-dichlorovinyl dimethyl phosphate) was added at specific intervals to cultures of human lymphocytes at concentrations ranging from 1 to 40 μg/ml. Subsequent examination showed that dichlorvos was cytotoxic to cells at concentrations of 5 to 40 μg/ml and that cytotoxicity was not accompanied by significant cytogenetic changes.
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  • 130
    ISSN: 1432-0738
    Keywords: Dichlorvos ; Teratology ; Inhalation ; Rat ; Rabbit ; Dichlorvos ; Teratologie ; Inhalation ; Ratte ; Kaninchen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Kaninchen und Ratten wurde die teratogene Wirkung von inhaliertem Dichlorvos untersucht. Im Versuch waren primipare Kaninchenweibchen der Rasse “Dutch” mit einem Anfangsgewicht von 2 bis 3 kg und primipare Rattenweibchen vom Stamm “Carworth Farm E“ mit einem Anfangsgewicht von 200 bis 300 g. Die Tiere wurden während der gesamten Trächtigkeit folgenden Konzentrationen in der Atemluft ausgesetzt: 0,25, 1,25 und 6,25 μg Dichlorvos pro Liter Luft. Ein zusätzliches Experiment am Kaninchen wurde mit 2 und 4 μg Dichlorvos pro Liter Luft durchgeführt. Die Behandlung wirkte weder beim Kaninchen noch bei der Ratte teratogen. Selbst Konzentrationen, die für die Kaninchen tödlich waren, und die eine deutliche Cholinesterasehemmung in Plasma, Erythrocyten und Gehirn der Ratten und Kaninchen hervorriefen, wurden ohne Schädigung für die Feten vertragen.
    Notes: Abstract The teratogenic potential of inhaled dichlorvos vapour for rabbits and rats was investigated on the offspring of primiparous female Dutch rabbits weighing 2 to 3 kg and primiparous female Carworth E strain rats weighing 200 to 300 g. The animals were exposed throughout pregnancy at concentrations of 0.25, 1.25 and 6.25 μg dichlorvos per litre of air. In an additional experiment pregnant rabbits were exposed to concentrations of 2 and 4 μg dichlorvos per litre of air. The results gave no indication that dichlorvos vapour is teratogenic in rabbits or rats even at exposure concentrations resulting in maternal deaths in rabbits, and causing depression of plasma, erythrocyte and brain cholinesterase activities in pregnant animals of both species.
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  • 131
    ISSN: 1432-0738
    Keywords: Dichlorvos ; Trimethyl Phosphate ; Ethyl Methanesulphonate ; Dominant Letal ; Mutagenesis ; Mouse ; Inhalation ; Dichlorvos ; Trimethylphosphat ; Äthylmethansulfat ; dominant letal ; Mutagenese ; Maus ; inhalation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Männliche CF1-Mäuse wurden 16 Std lang Dichlorvos-konzentrationen von 30 und 55 μg/l in der Atemluft ausgesetzt, oder sie wurden 4 Wochen lang 23 Std am Tag in einer Atmosphäre gehalten, die 2,1 bzw. 5,8 μg/l Dichlorvos enthielt. Bei den nachfolgenden Paarungen während 8 Wochen kam es nicht zu mutagenen Effekten im Sinne eines gesteigerten frühen Fetaltodes oder präimplantativen Verlustes. Die Fertilität der Männchen blieb unbeeinflußt.
    Notes: Abstract Male CF1 mice were exposed to atmospheres containing dichlorvos at concentrations of 30 and 55 μg per litre of air for 16 h, or to 2.1 and 5.8 μg per litre for 23 h daily for 4 weeks. These exposures to dichlorvos produced no mutagenic effects as expressed by increased pre-implantation losses or early foetal deaths in subsequent test matings. No impairment of male fertility was detected following the exposures to dichlorvos vapour.
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  • 132
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    Archives of toxicology 30 (1972), S. 67-74 
    ISSN: 1432-0738
    Keywords: Mutagenic Effect ; Organophosphorus Compounds ; Pesticides ; Dichlorvos ; Mutagene Wirkung ; Organophosphate ; Pestizide ; Dichlorvos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Neun Organophosphorsäurepestizide und zwölf chemische Mutagene wurden an Escherichia coli WP 2-Agarkulturen auf mutagene Wirkung im Sinne einer Steigerung der Rückmutationsrate getestet. Außerdem wurden Bidrin, Dichlorvos und 4 alkylierende Substanzen an 2 geeigneten Stämmen der Serratia marcescens mit Hilfe der Paper-disc-Methode geprüft. Die Organophosphorsäurepestizide erhöhten nicht die Rückmutationsrate bei E. coli WP 2. Bidrin war auch nicht mutagen im Test mit Serratia marcescens. Dichlorvos erhöhte die Rückmutationsrate dosisabhängig an beiden Stämmen von Serratia marcescens. Die fehlende mutagene Wirkung von Dichlorvos am Säugetier wird unter Berücksichtigung der schnellen Metabolisierung diskutiert.
    Notes: Abstract Nine organophosphorus pesticides and twelve known chemical mutagens were applied to agar plate cultures ofEscherichia coli WP 2. After incubation, the cultures were examined for an increase in reverse mutation rate. Dicrotophos and dichlorvos, and four alkylating agents were tested against two mutant strains of Serratia marcescens using the paper disc technique. The organophosphorus pesticides did not increase the reversion rate inEscherichia coli WP 2. Dicrotophos was also negative when tested against Serratia marcescens. Dichlorvos induced a dose-related increase in reversion rate in both strains of Serratia marcescens. The significance of the results are discussed in relation to the rapid metabolism of dichlorvosin vivo and the absence of any mutagenic effect in mammalian test systems.
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  • 133
    ISSN: 1432-0738
    Keywords: Imipramine ; Dketection ; Postmortem Changes ; Conservation ; Imipramin-Nachweis ; Postmortale Veränderungen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Postmortale Veränderungen des Imipramin-Gehaltes in biologischem Material führten während einer Beobachtungszeit von 90 Tagen zu einem Absinken der Ausgangswerte, wenn die Organe bei Raumtemperatur aufbewahrt wurden. Dagegen waren die Bestimmungen bei Kühlschrankaufbewahrung (+4°C) bis zu 30 Tagen gut vergleichbar und erreichten auch nach 90 Tagen erst maximal 16% Verluste. Der Nachweis von Imipramin ist deshalb auch nach Exhumierung noch erfolgversprechend.
    Notes: Abstract Postmortal changes of imipramine content in biological material caused a fall in the initial values during an observation period of 90 days, when the organs were kept at room temperature. On the other hand the results of the estimation were comparable with the initial ones, when the organs were stored in a refrigerator (+4°C) until 30 days and suffered only after a 90 day storage a maximal loss of 16%. The detection of imipramine is on this account promising even after exhumation.
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  • 134
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    Archives of toxicology 28 (1972), S. 72-76 
    ISSN: 1432-0738
    Keywords: Lignocaine (Lidocaine®) ; Antiarrhythmics ; Intoxication ; Cerebral Symptoms ; Liver Parenchyma Defects ; Xylocain (Lidocain®) ; Antiarrhythmika ; Intoxikation ; cerebrale Symptome ; Leberparenchymschäden
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An Hand einer eigenen Beobachtung wird auf die cerebralen Komplikationen bei Xylocain-Überdosierung hingewiesen. Krämpfe mit vorwiegend extrapyramidaler Symptomatic und Atemstillstand waren die Intoxikationserscheinungen bei einem Patienten, dem 1600 mg Xylocain in 8 min infundiert wurden. Ein Absinken des arteriellen Blutdruckes wurde darunter nicht beobachtet. Intraatriale und intraventriculäre Erregungsausbreitung blieben unverändert, die atrioventriculäre Überleitung wurde zu einem av-Block ersten Grades verlängert. Es wird darauf hingewiesen, daß Schock, Hypovolämie und Leberfunktionsstörungen die Toxicität von Xylocain erhöhen. Unter diesen Umständen muß nach Xylocain mit cerebralen Nebenerscheinungen gerechnet werden.
    Notes: Abstract The author refers on the basis of his own observation to the cerebral complications following an overdose of lignocaine. Cramps with predominances extrapyramidal symptomatology and apnoe were seen in a patient who received an infusion of 1600 mg lignocaine within 8 minutes. No decrease in the arterial blood pressure had been observed. Intra-atrial and intraventricular conduction remained unchanged; the atrioventricular conduction velocity decreased to a first degree av-block. It is noted that shock, hypovolaemia and hepatic insufficiency increase the toxicity of lignocaine. Under these circumstances, cerebral secondary effects might arise after lignocaine administration.
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  • 135
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    Archives of toxicology 28 (1972), S. 270-278 
    ISSN: 1432-0738
    Keywords: Poisoning ; Ammonium Compounds ; Cobalt8 ; Copper ; Nickel ; Vergiftung ; Ammonium-Verbindungen ; Kobalt ; Kupfer ; Nickel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein tödlicher Vergiftungsfall durch eine kommerzielle Mischung von Substraten der Pflanzenwuchsmittel berichtet. Das Präparat enthielt viele anorganische Verbindungen, wie Salze der Schwermetalle, Amoniumverbindungen und Nitrate. Das Vergiftungsbild bestand aus schweren Nierenversagen, Leberinsuffizienz und Ateminsuffizienz. Der Patient wurde mit Hämodialysen und künstlicher Beatmung behandelt. Trotz Beatmung mit 100% igem Sauerstoff blieb er hypoxämisch während der 2 letzten Tage und nach Intensivbehandlung von 7 Tagen starb er durch Asystolie. Die Resultate der toxikologischen Experimente mit Kaninchen zeigten, daß die Toxicität des Präparates auf der kombinierten Wirkung von NH+, Cu++, Ni++ und Co++ beruhen kann.
    Notes: Abstract A fatal case of a poisoning caused by a commercial mixture of plantnutrient substrates is described. The preparation contained numerous inorganic compounds, such as heavy metal salts, ammonium compounds and nitrates. The patient developed severe renal, hepatic and respiratory failure. He was treated with five haemodialyses and finally his ventilation was controlled mechanically via a tracheostomy. In spite of ventilation with 100 % oxygen he remained hypoxaemic during the last two days and after intensive therapy for seven days he developed a fatal cardiac asystole. The results of toxicological experiments performed on rabbits show that the toxicity of the preparation may be due to the combined action of NH+ with Cu++, Ni++ and Co++. The histopathological findings made in the patient and the animals are compared.
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  • 136
    ISSN: 1432-0738
    Keywords: Brain Diseases ; Manganese ; Chronic Intoxication ; Hirnerkrankungen ; Mangan ; Chronische Vergiftung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Einmalige intratracheale Verabfolgung von Mangandioxid (400 mg) an Kaninchen erzeugte chronische Manganvergiftung mit Lähmung der Hinterextremitäten. 24 Monate später werden die Tiere getötet und die Adenosindeaminase-Aktivität wird in Liquor, Gesamtgehirn und Serum, das Proteinmuster in Serum und Liquor bestimmt. Die Gesamtproteine im Serum sind um 23 % erhöht infolge Globulinvermehrung. Im Liquor ist die Albumin- und Globulin-Konzentration deutlich vermindert bei erniedrigtem Gesamtprotein. Unser Befund einer deutlichen Erhöhung der Adenosindeaminase-Aktivität allein im Liquor deutet an, daß dieser Test als klinisch-diagnostische Probe bei Patienten mit chronischer Manganvergiftung eingesetzt werden könnte.
    Notes: Abstract Chronic manganese toxicity was produced in rabbits by intra-tracheal administration of manganese dioxide (400 mg); resulting in hind limb paralysis. The animals were sacrificed at a period of 24 months. Adenosine deaminase activity was determined in cerebrospinal fluid (CSF), whole brain and serum, whereas protein patterns were studied only in serum and CSF. The total serum proteins increased by 23% due to increase in globulins. In CSF there was marked reduction in the concentration of albumin and globulins, thus, resulting in significant lowering of total proteins. Further our findings of marked elevation in adenosine deaminase only in CSP of experimental animals suggests that this test may be used as a clinical diagnostic index in patients with chronic manganese poisoning.
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  • 137
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    Keywords: Bromination ; Thin Layer Chromatography ; Barbiturates (Allional, etc. see German Key words) ; Bromierung ; Dünnschichtchromatographie ; TRT-Technik ; Barbiturate (Allional, Amobarbital, Brallobarbital, Butabarbital, Butallylonal, Butethal, Evipan, Itobarbital, Luminal, Medomin, Metharbital, Nealbarbital, Pentobarbital, Phanodorm, Prominal, Propallylonal, Rectidon, Secobarbital, Speda, Talbutal, Veronal)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Durch Behandeln mit Brom am Startpunkt zweidimensionaler Dünnschichtchromatogramme lassen sich viele Barbiturate reproduzierbar in Derivate überführen. Die nachfolgende Trennung gibt Aufschluß über die Struktur und führt anhand der Rf-Werte der Bromaddukte (die sich nach einem mitgeteilten Schema bilden) in den meisten Fällen zu einer genauen Spezifizierung. Die Methode ist auch auf Barbituratgemische anwendbar.
    Notes: Abstract By means of treatment with bromine at the starting point of two dimensional thin layer chromatograms, many barbiturates may be converted to reproducible derivatives. The subsequent separation provides structural information and in nearly all investigated examples permits exact specification of the brominated compounds by way of their Rf values, a scheme of which is included in the article. The method is also applicable to mixtures of barbiturates.
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  • 138
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    Archives of toxicology 28 (1972), S. 302-304 
    ISSN: 1432-0738
    Keywords: Botulinus Intoxication ; Black Widow Spider ; Latrodectus Tredecimguttatus ; Botulinus-Vergiftung ; Latrodectus Tredecimguttatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das Gift von Latrodectus Tredecimguttatus, das an der demyelisierten motorischen Faser Acetylcholin freizusetzen vermag, verlängert an Mäusen mit Vergiftung durch Botulinus-Toxin A signifikant die Überlebenszeit.
    Notes: Abstract The venom of the black widow spider, Latrodectus Tredecimguttatus, which is capable of liberating acetylcholine in demyelinated motor nerve fibres, enhances significantly the survival time of mice intoxicated with botulinus toxin A.
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  • 139
    ISSN: 1432-0738
    Keywords: Ajmalin ; Isolation ; Identification ; Quantitative Determination ; Ajmalin-Isolierung ; Identifizierung ; Quantitative Bestimmung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Identifizierung erfolgte chromatographisch an Kieselgel G bzw. Whatman-Papiers Nr. 2, unter Anwendung von Ehrlich-Reagens als Farbtest. Die spektro-photometrische Analyse der Zonen des Verteilungschromatogramms ergab eine Kurve mit charakteristischen Absorptionsmaxima bei der maximalen Absorption 287–289 nm. Die quantitative Bestimmung des Alkaloides Ajmalins erfolgte chromatographisch auf Kationenaustauscherpapier. In der vorliegenden Arbeit wird eine Methode zur Isolierung des Alkaloides Ajmalin aus Organen und Körperflüssigkeiten beschrieben. Dargestellt wird eine Methode zur Absonderung des Alkaloides Ajmalin aus dem Sektionsmaterial, wenn es in selbstmörderischer Absicht in Form des Heilmittels eingenommen wurde.
    Notes: Abstract A method is described for the isolation of the alkaloid ajmalin from autopsy material in cases where the drug “Ajmalin” has been taken for suicidal purposes. The identification of the alkaloid is carried out by means of T.L.C. on Silicagel G and by P. C. on Whatman No. 2 paper using Ehrlich's reagent for detection. Spectrophotometeric analysis of the zones eluted from the separation chromatograms gives a curve with characteristic peak of maximal absorption at 287–289 μm. The quantitative determination of the alkaloid ajmalin is performed using a Chromatographic technique on cation exchange paper.
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  • 140
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    Keywords: Toxicity of Caffeine ; Toxicity of Nitrite ; Toxicity of Isophthalanilide ; Toxicity of Mercaptopurine ; Growth Rate of Rats ; Methemoglobinemia in Rats ; Hemolytic Anemia in Rats ; Stained Urinary Cells ; Renal Functions in Rats ; Red Blood Cell Counts in Rats ; White Blood Cell Counts in Rats ; Urinary Dilution ; Clearance of Free Water ; Osmolar Clearance ; Maximal Urinary Osmolarity ; Proteinuria in Rats ; Hemolysis Induced by i.v. Water ; Coffein: Toxicität ; Caffeinum: Toxicität ; Nitrite: Toxicität ; Isophthalanilid: Toxicität ; Mercaptopurin: Toxicität ; Wachstumsgeschwindigkeit von Ratten ; Methämoglobinämie bei Ratten ; Hämolytische Anämie bei Ratten ; Gefärbte Harnsedimente ; Nierenfunktionen der Ratte ; Erythrocyten: Zahl bei der Ratte ; Leukocyten: Zahl bei der Ratte ; Harnverdünnungsmechanismus ; Clearance des freien Wassers ; Osmotische Clearance ; Maximale Harnosmolarität ; Proteinurie bei der Ratte ; Hämolyse durch i.v. Wasserinjektion bei der Ratte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die allgemeine und renale Toxicität von großen Dosen von Phenacetin, Paracetamol und potentiell nephrotoxisehen Antimitotica, sowie anderen üblichen Bestandteilen von analgetischen Mischpräparaten wurde an Ratten in 30–60 Tage-Versuchen untersucht. Phenacetin und Paracetamol hemmten Futteraufnahme und Wachstum. 800–1200 mg/kg · Tag Paracetamol tötete mehr Tiere als 1500–3000 mg/kg · Tag Phenacetin. Die beiden Analgetica und das Antimitoticum Isophthalanilid riefen hyperchrome Anämie hervor. Phenacetin verursachte mehr Methämoglobinämie als Paracetamol. Weder dieser Analgetica, noch Coffein, noch Natriumnitrit, noch Isophthalanilid, noch Mercaptopurin verringerten das Glomerulusfiltrat, die maximale Harnkonzentrierungsfähigkeit nach Durst unter Vasopressin, die Harnverdünnuungsfähigkeit nach hypotonischen Infusionen oder die renale H+-Ionen-Sekretion. Phenacetin, Paracetamol und Isophthalanilid verringerten die fraktionelle renale Harnstoffausscheidung. Sehr große Dosen von Paracetamol steigerten leicht die Proteinurie und die Ausscheidung von Tubuluszellen im Harn. Phenacetin und Paracetamol verursachten degenerative Veränderungen im histologischen Bild der corticalen, proximalen und distalen Tubuli, die unter Blindbedingungen untersucht wurden. Es traten weder entzündliche Veränderungen, noch Schädigungen des Nierenmarks oder der Papille auf. Die corticalen degenerativen Veränderungen ließen sich nicht als Folge von Methämoglobinämie oder Hämolyse erklären. Isophthalanilid verursachte eine „Normalisierung” des histologischen Bilds der Nierenrinde über die Norm hinaus. Die Ausscheidung von Tubuluszellen im Harn war nicht signifikativ mit der Schwere der histologischen Veränderungen korreliert. Die Befunde führen zum Schluß, daß weder Phenacetin, noch Paracetamol bei der Ratte ausgeprägte nephrotoxische Wirkungen besitzt.
    Notes: Abstract The general and the renal toxicity of large doses of phenacetin, paracetamol, some antimitotic drugs and other constituents of analgesic mixtures was investigated in medium term toxicity tests in a large number of rats. Phenacetin and paracetamol depressed food intake and retarded growth. 800–1200 mg/kg · day paracetamol induced a larger mortality than 1500–3000 mg/kg · day phenacetin. Both analgesics and isophthalanilide, an antimitotic agent, induced hyperchromic anemia. Phenacetin induced methemoglobinemia more readily than paracetamol. Neither the analgesics, nor caffeine, sodium nitrite, isophthalanilide or mercaptopurine depressed GFR, maximal urinary concentration after dehydration plus vasopressin, urinary dilution after hypotonic expansion, or urinary acidification. Phenacetin, paracetamol and isophthalanilide depressed the fractional excretion of urea by the kidney. Very large doses of paracetamol slightly increased the proteinuria and the urinary excretion of tubular cells. Phenacetin and paracetamol induced degenerative histological alterations in cortical proximal and distal tubules, detected and quantitated under blind conditions. There were no inflammatory changes, nor any medullary or papillary lesions. The degenerative lesions could not be explained by the presence of methemoglobinemia or hemolysis. Isophthalanilide actually “improved” the histological appearance of the kidneys. The urinary excretion of tubular cells was not significantly correlated with the severity of the histological changes. It was concluded that neither phenacetin nor paracetamol exert major nephrotoxic effects in rats.
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  • 141
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    Archives of toxicology 28 (1972), S. 305-370 
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    Topics: Medicine
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  • 142
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    Biological cybernetics 10 (1972), S. 32-37 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Some common features of neural transformations along sensory pathways are discussed. The emphasis is on spatial mapping in the visual system, but close parallels exist in temporal visual mapping as well as other sensory systems. The role played by lateral inhibition in sequential transformations is investigated by direct computation and by mathematical analysis.
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  • 143
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Summary In this work the methods of the communication theory for binary detection, multiple detection and extraction are applied to biological systems. It is the objective of this investigation to compare the performance of optimal and biological systems in receiving signals superimposed by noise. The required mathematical relations and methods of measurements are derived. In the second part of this work pattern recognition experiments (multiple detection) at the human visual system with stationary and time variant patterns are described. The comparison of the performance between optimal and biological system shows that the human visual system acts in a suboptimal way. From some other detection experiments it can be concluded that the recognition process is describable by spatial cross-correlation.
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  • 144
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    Biological cybernetics 10 (1972), S. 16-31 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Description / Table of Contents: Summary The visual system of vertebrates represents a pattern recognition system processing optical information in neural networks parallelly. One can interpret the networks as filters for spatial frequencies. To describe its properties a mathematical model is used. Supposing a linear and homogenous connection of neural cells the model is based on the principles of excitation and inhibition. Especially, the changes of the filter characteristics are shown for the case the time-dependence of the optical input patterns being a stepfunction. Results are shown for one- and twodimensional spatial filters with different time behaviour of the inhibiting mechanism. Applying the derived expressions to the visual system of the cat, it is shown that the retina of the cat changes during the transient process from a low-pass for spatial frequencies into a low-pass-band-pass-system with phase inversion.
    Notes: Zusammenfassung Das visuelle System von Vertebraten stellt ein Mustererkennungssystem dar, das optische Information in Netzwerken von Neuronen parallel verarbeitet. Die Netzwerke kann man als Filter für Ortsfrequenzen auffassen. Zur Beschreibung ihrer Eigenschaften wird ein mathematisches Modell verwandt, das eine lineare und homogene Verknüpfung von Nervenzellen annimmt und auf den Prinzipien von Streuungs- und Hemmungsverkopplung basiert. Die Arbeit fragt insbesondere nach der Veränderung der Charakteristik des Ortsfilters, wenn das optische Muster sprunghaft an den Filtereingang gelangt. Ergebnisse liegen für einund zweidimensionale Ortsfilter mit unterschiedlichem Zeitverhalten des Hemmungsmechanismus vor. Die Anwen dung der hergeleiteten Ausdrücke auf das visuelle System der Katze zeigt, daß die Retina von Katzen während des Einschwingvorgangs von einem Tiefpaß für Ortsfrequenzen zu einem Tiefpaß-Bandpaßsystem mit Phasensprung wird.
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  • 145
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    Biological cybernetics 10 (1972), S. 38-44 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Taking into account Caianiello's work of 1961 a model of a neuron quite similar to his is proposed and studied. For this model, where a temporal summation and a period of refractoriness are assumed, a mathematical approach and a simulation on computer were realized. Particular types of nets were used, namely: nets with topological structures, and fully random nets. The difference between the two types is that the first type has a two-dimensional square structure and depends on the rules of the formation of connection between the neurons, while the second type is realized by means of the probability distribution function governing the formation of the structure of the net. These types of neural nets are analysed by means of a method which permits to obtain various parameters which characterize their behaviour in time and space in terms of the trajectory of the system. Many experiments are also reported; the statistical analyses, made on them, show the great importance and influence of refractoriness on the behaviour of neural networks. In the last part of the work an interesting case is reported, in which the reaction of the net to a disturbance shows that a kind of adaptation takes place, although the structure of the net stays unchanged.
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  • 146
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract In the following paper we develop a general model for properties of identification and prediction of human tracking movements as a synthesis of experimental results and mathematical methods. The applicability of this general concept is checked by way of simulation of the eyetracking-system on a digital computer. We suggest a parallel system, which coordinates prediction by way of extrapolation and reproduction with error-correction. The simulation of the experimentally found principles of information-processing (signal-identification, extrapolation, reproduction, error-correction, control of performance) has turned out to be an adequate functional description, so far as it can be proved by comparison of the results in the experiments and in the simulation.
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  • 147
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    Biological cybernetics 10 (1972), S. 58-60 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A mathematical analogy between the holographic models of temporal memory and Reichardt's optomotor theory is stressed. It is pointed out that the sequence of operations which is essential to any holographic model of brain functioning is actually carried out by a nervous structure in the optomotor behaviour. Some implications in both the optomotor theory and the hypothesis of neural holographic processes are further suggested.
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  • 148
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Reversal of perspective for ambiguous optical stimuli (Necker cube, Schröder staircase, honeycomb) has been studied, determining the statistical distribution of time intervals spent on each percept. The experimental distributions can be fitted with the gamma function, characterized by two parameters n, b. The two parameters are not independent, showing a correlatiomn ϱ = 0.74. Subsequent intervals appear to be largely independent; from the beta distribution for the fraction of time spent on a given percept, one can show that the subjects differ only in regard to the variance of this variable.
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  • 149
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A mathematical model of a neuron was developed to investigate the effects of various spatio-temporal patterns of miniature dendritic input potentials on neuronal somatic potentials. The model treats spatio-temporal dendritic activation patterns as the input or forcing function in the non-homogeneous cable equation. The theoretical somatic potentials resulting from several different spatio-temporal input patterns were generated on an IBM 360/75 computer. The model allows the investigation of the theoretical effects of activations at several different synaptic sites, of repeated activations at one or more sites, and of changes in various parameters. The time-to-peak and amplitude of individual excitatory postsynaptic potentials, distance of synapses from the soma, and interactivation interval for repeated activations at the same synapse were among the parameters investigated. Not only the order of activations at different synaptic sites was important, but the time intervals between activations were shown to be important. For a given order of activations at different synapses, optimum time intervals between activations were demonstrated, with respect to the resulting peak somatic potentials. Possible consequences of some hypothetical learning and memory mechanisms upon neuronal excitability were discussed. It was also shown that a deterministic model can generate theoretical curves which appear to be almost of a random nature with respect to the observed numbers and amplitudes of peaks of individual EPSPs. The conditions for the appearance of extra peaks were discussed.
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  • 150
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    Biological cybernetics 11 (1972), S. 112-117 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The oculomotor system, as far as horizontal voluntary eyemovements are concerned, is analyzed by way of average gain and phase frequency plots based on sinusoidal and random noise inputs. On account of the non-linear properties of the system, it is not possible to obtain an overall-transfer-function, but nevertheless frequency-responses are sufficiently appropriate to demonstrate the system-performance using different types of signals. Frequencyresponses are significantly different for sinusoidal and random inputs, because of the interference of the saccadic component. On the other hand, gain and phase, to a certain extent, turn out to be independent of the amplitude of the input.
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    Biological cybernetics 11 (1972), S. 119-122 
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    Notes: Abstract Afferent discharges from single muscle spindles in the frog were recorded from the dorsal root ganglion in the reflexively active loop and in the same loop opened by cutting the dorsal roots. The closed loop response (i.e. pulse frequency) to muscle stretch was smooth and without “dead zones”, as compared to the response to the same stretch when the loop was open. The variations in gain between the open and closed loop modes of operation are shown to be small, both for muscle spindle afferent outflow and for muscle tension.
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  • 152
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    Biological cybernetics 11 (1972), S. 123-129 
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    Notes: Abstract The muscle spindles (MS) have been proposed by Merton (1953), to be the sensors supplying a feedback signal in the muscle length follow-up servo system. This system is analyzed here, based on the two engineering requirements for man made servo systems, namely the system loop gain and the steady state error (Gille, 1959). In the first part the system's linearized transfer function equations are developed. It is shown that the small loop gain found in the reflex studies indicates a small gain under volitional control of movements, i.e. volitional control is being exercised directly by the alpha or gamma system. For the steady state error no definite conclusions can be drawn from the available data (Rosenthal, 1970; Houk, 1963); however, it is shown to be inversely proportional to the steady state loop gain, and the system is thus of type “0” or “1”.
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  • 153
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    Biological cybernetics 11 (1972), S. 130-141 
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    Topics: Biology , Computer Science , Physics
    Notes: Abstract As an extension of a previous paper (Inbar, 1972/II) wherein the servo model of muscle control was analyzed and found insufficient in describing muscle control phenomena, an optimal adaptive model is proposed, where muscle spindles serve as the sensors of muscle dynamics. The concept of an adaptive system is defined and illustrated within the framework of an algorithmic adaptive, or “learning” scheme. A speculative attempt is made to correlate the various adaptive model components with the anatomical structures involved in muscle control. The paper concludes with a general discussion of the adaptive system approach to physiological systems.
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  • 154
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    Biological cybernetics 11 (1972), S. 142-147 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract In a previous paper (Inbar, 1972/III) a new adaptive model was proposed for muscular control. According to that scheme muscle spindles (MS) supply continuous information about the system dynamics. In the present study integral pulse frequency modulation (IPFM) is used to correlate MS afferent signals, recorded from frog sartorius muscle, to the same muscle dynamics, in order to establish the feasibility of the proposed MS role in the adaptive muscle model.
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  • 155
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    Notes: Abstract An earlier proposed model of the de-efferented muscle spindle mechano-receptors has been developed further to simulate the effects of the dynamic fusimotor (γ D) activation of the group Ia afferents (primary endings). The rate sensitivity of the original second order receptor model might be increased simply by increasing the overall viscous damping of the simulated polar regions of the nuclear bag fibre. However, adequate simulation of the typical time course of the stretch response of the primary endings during γ D-activation required a subdivision of the polar regions into an active and a passive part. A reasonable behaviour of the model was obtained by simulating a local contraction covering about 50–90% of the polar regions of the nuclear bag fibres. The ramp response of the model showed a “quick” rate response component that increased by increasing the rate of the simulated stretch. This component was not significantly influenced by the simulated γ D-activation. A “slow” rate component appeared to increase approximately in the same proportion as the intensity of the simulated γ D-activation. The behaviour of the model closely corresponds to that of the biological prototype. The study demonstrates that the electrophysiological effects of activating the dynamic fusimotor fibres are indeed compatible with peripheral mechanical events associated with contraction phenomena within the polar regions of the nuclear bag intrafusal muscle fibres.
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  • 156
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    Biological cybernetics 11 (1972), S. 154-165 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Networks of mutually inhibiting neurons are analyzed and simulated on a digital computer. In the analysis and simulation a continuous-variable model of the neuron is used as the basic element. It consists of a many-input adder, a first-order low-pass filter and a diode-type nonlinearity. A mutually inhibiting network is formed by connecting the output of every element to inputs of the other elements through weight-coefficient setting units. Each element of the network is assumed to receive a certain number of constant inputs from elements of other networks. An autonomous system of nonlinear differential equations is introduced to describe the network dynamics, and the steady-state solutions of the system are investigated in detail. The network has a unique equilibrium solution, multiple equilibrium solutions or a periodic solution depending on the weight-coefficients and the inputs. It is shown that these three cases correspond to three types of information processing functions: the sharpening of input patterns, the temporary storage of information and the generation of periodic signals.
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  • 157
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Subjects who received EEG alpha feedback recorded from two homologous scalp areas (central-temporal) were trained to have ON-OFF control over the left and right sides. The partial success in demonstrating localized control suggests that subjects may be trained for very specific control. Localized training may be used to partition the subjective, conscious and behavioral experiences associated with selected EEG patterns and to develop an independent subjective physiological language. Applications to medicine and altered states of consciousness are discussed.
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  • 158
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Extracellular unit recordings were derived from the cat sensorimotor cortex by means of tungsten microelectrodes. Evidence was obtained for the value of time-locking of impulses: a critical time interval was demonstrated as essential for modifications caused in putaminally-evoked cortical local field potentials by preconditioning stimuli delivered to the nucleus entopeduncularis. A correlation analysis was carried out on responses of neurones of the sensorimotor cortex to stimulation of the pyramid or of sensory area S 1. Differentiation was made between common input and sequential firing operational conditions. Logics of and-gate and of conditional or-gate were recognized. Micro-circuitry was offered in each case. Evidence was offered for the importance of collaterals in such actions.
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  • 159
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 11 (1972), S. 175-177 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Experimental results are given for the performance of a vernier task without visual input. Entropies obtained from the distribution of errors in performing this task are compared with entropies obtained from earlier experiments with visual input. The entropy difference gives the information in bits transmitted by the visual system. An information capacity for the visual system in performing the vernier task is deduced on the assumption that temporal summation of information is limited by the occurrence of an involuntary saccade.
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  • 160
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 11 (1972), S. 178-178 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Type of Medium: Electronic Resource
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  • 161
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A mathematical model to offer an explanation of the pause in firing of a primary muscle spindle at the transition between dynamic and static stretch is suggested. It is proposed that the firing frequency is proportional to a “generator current” at the site of the transduction (presumably the five terminal endings) and that the receptor potential is a version of this current filtered by the passive cable properties of the nerve between site of transduction and site of measurement. A mathematical expression is derived for the receptor potential from data in the literature. From this and an equivalent circuit of the nerve, an expression for the generator current is derived.
    Type of Medium: Electronic Resource