TY - JOUR A1 - Tacke, Reinhold A1 - Lange, Hartwig A1 - Bentlage, Anke A1 - Sheldrick, William S. A1 - Ernst, Ludger T1 - 2.2.5.5-Tetraorganyl-1.4-dioxa-2.5-disilacyclohexane/2,2,5,5-Tetraorganyl-1,4-dioxa-2,5-disilacyclohexanes JF - Zeitschrift für Naturforschung B N2 - The 2,2,5,5-tetraorganyl-1,4-dioxa-2,5-disilacyclohexanes 2a-2c were prepared by condensation of the corresponding (hydroxymethyl)diorganylsilanes 1 a-1 c. The constitution of the heterocycles was confirmed by elemental analyses, cryoscopic measurements, mass spectrometry, and NMR-spectroscopic \((^1H, ^{13}C)\) investigations. The molecular structure of 2 b was determined by X-ray diffraction analysis. KW - 1,4-Dioxa-2 KW - 5-disila-cyclohexane ring system KW - synthesis KW - structure Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128423 VL - 38 IS - 2 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Lange, Hartwig A1 - Sheldrick, William S. A1 - Lambrecht, Günter A1 - Moser, Ulrich A1 - Mutschler, Ernst T1 - Sila-Pharmaka, 31. Mitt. [1] Synthese, Struktur und pharmakologische Eigenschaften von Diphenyl(2-piperidinoethoxymethyl)silanol und seinem Kohlenstoff-Analogon T1 - Sila-Pharmaca, 31 th Communication [1] Synthesis, Structure, and Pharmacological Properties of Diphenyl(2-piperidinoethoxymethyl)silanol and its Carbon Analogue JF - Zeitschrift für Naturforschung B N2 - In the course of systematic investigations on sila-substituted parasympatholytics the diphenyl(2-aminoethoxymethyl)silanols 3b and 4b (and its carbon analogue 4a) were synthesized and characterized by their physical and chemical properties. In the solid state 4a and 4b form strong O-H---N hydrogen bonds, which are intramolecular (4a) and intermolecular (4b), respectively. 4a and 4b were found to be weak antimuscarinic agents (4b >4a) and strong papaverine-like spasmolytics (4a ≈4b). KW - antimuscarinic and papaverine-like activity KW - sila-substitution KW - crystal and molecular structure Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128410 VL - 38 IS - 6 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Linoh, Haryanto A1 - Stumpf, Burghard A1 - Abraham, Wolf-Rainer A1 - Kieslich, Klaus A1 - Ernst, Ludger T1 - Mikrobiologische Umwandlung von Silicium-Verbindungen: Enantioselektive Reduktion von Acetessigsäure-(trimethylsilylalkyl)estern und deren Carba-Analoga T1 - Microbiological Transformation of Silicon Compounds: Enantioselective Reduction of Trimethylsilylalkyl Acetoacetates and their Carba-Analogues JF - Zeitschrift für Naturforschung B N2 - The trimethylsilylalkyl acetoacetates 1 b and 2 b as well as their carba analogues 1 a and 2 a have been reduced microbiologically by Kloeckera corticis (ATCC 20109), leading to the corresponding ( + )-3(S)-hydroxybutanoates 3b, 4b, 3a, and 4a. The enantiomeric purity was found to be 80% (3a, 3b, 4b) and 65% (4a), respectively. The reduction of lb and 2b is - to our knowledge - the first example for a controlled microbiological transformation of organosilicon substrates. KW - enantioselective reduction KW - microbiological transformation KW - silicon compounds Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128304 VL - 38 IS - 5 ER - TY - JOUR A1 - Herbert, Michael T1 - Elektronenmikroskopisch-morphometrische Untersuchungen am Nierenhauptstiick männlicher und weibliche Ratten nach Kastration und Testosteronsubstitution T1 - Electron Microscopic and Morphometric Study on the Renal Proximal Tubule of Male and Female Rats Following Castration and Substitution with Testosterone JF - Zeitschrift für mikroskopisch-anatomische Forschung N2 - No abstract available. Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-127682 VL - 97 IS - 2 ER - TY - JOUR A1 - Wilhelm, Gernot T1 - Der hurritische Ablativ-Instrumentalis /ne/ N2 - No abstract available. KW - Churritisch Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87668 ER - TY - JOUR A1 - Schneider, Wolfgang A1 - Zielinski, Werner T1 - Vergleichende Bedingungsanalysen zur Performanz guter und schwacher Rechtschreiber T1 - A comparison of structural models describing and explaining spelling performance of good and poor spellers N2 - Es wurde die Frage überprüft, ob für schwache Rechtschreiber und rechtschreibunauffällige Schüler ähnliche Determinanten der Rechtschreibleistung angenommen werden können. Theoretisch plausible Kausalmodelle zur Beschreibung und Erklärung von Rechtschreibleistungen rechtschreibschwacher und rechtschreibunauffälliger Viertkläßler wurden im Hinblick auf ihre Übereinstimmung und Datenkompabilität anhand des Computerprogramms LISREL IV analysiert. Für beide Gruppen ergaben sich unterschiedlich strukturierte Lösungen, von denen lediglich die für die normalen Rechtschreiber hinsichtlich der Datenanpassung und des Prozentsatzes aufgeklärter Kriteriumsvarianz einigermaßen befriedigen konnte. N2 - In the present study, an attempt was made to simultaneously test causal models of spelling performance for two samples of fourth grade dyslexic children and normal speUers. The computer program LISREL IV was used to answer the question if the same structural model holds for both samples. Different solutions were obtained for both groups. While the models all showed an acceptable data fit, only the solution for the normal spellers explained enough criterion variance to be practically important. KW - Rechtschreibschwäche Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87297 ER - TY - JOUR A1 - Schneider, Wolfgang A1 - Scheibler, D. T1 - Probleme und Möglichkeiten bei der Bewertung von Clusteranalysen: I. Ein Überblick über einschlägige Evaluationsstudien T1 - On the evaluation of dustering algorithms: An integrative review T1 - Procédés de Cluster-analyse N2 - Es wird ein Oberblick über Evaluationsstudien gegeben, die sich mit der Validität von Clusteranalyse-Algorithmen befassen. Im Anschluß an die Diskussion möglicher Bewertungskriterien werden Vergleichsuntersuchungen näher analysiert und danach geordnet, ob sie empirische Datensätze, Plasmaden oder Monte-Carlo-Datensätze als Evaluationsgrundlage benutzen. Die Obersicht über komplexer angelegte Monte-Carlo-Studien zeigt die unterschiedliche Qualität der verfügbaren Clusteranalyse-Algorithmen auf, macht andererseits aber auch deutlich, daß bestimmte hierarchisch-agglomerative Verfahren wie etwa die Methoden nachWARD oder LANCE-WILLIAMS bzw. iterativpartitionierende Prozeduren wie etwa die KMEANS-Algorithmen als relativ robuste Klassifikationsverfahren gelten können. N2 - This paper presents a critical review of research on the evaluation of dustering algorithms. The review includes studies using empirical data sets and studies using so-called "plasmodes" (i. e., empirical data sets with known distributional parameters), but particularly concentrates on investigations using Monte-cario data sets. Although it turns out to be very difficult to come to a valid evaluation of the various clustering algorithms, hierarchical-agglomerative procedures like WARDsand LANCE-WILUAMs methods as well as the KMEANS algorithms appear to be most robust. N2 - L'article suivant pn!sente une revue des etudes d'evaluation qui relevent de validite d'analyse de Cluster-Algorithme. Des experiences de comparaison sont analysees et classees a Ia Suite de la discution de criteres de jugement possible. Ceux-ci suivent un ordre donne par l'utilisation de donnees qui ont ete relevees empiriquement, «Plasmoden>> ou bien de donnees empiriquement accumulees selon Je principe d'evaluation de Monte-Carlo. La revue d'etude complexe Monte-Carlo montre Ia difference qualitative des analyses Cluster algorithme et, d'autre part met clairement en valeur, que des procedes hierarchiques-agglomeratifs, comme la methode de WARD ou LANCE-WILLIAMS, par exemple - c'est-a-dire des procedes «iteratif-partitionierende» {iteratif comme par exemple, les algorithmes KMEANS, qui peuvent etre consideres comme procedes de classification robuste. KW - Cluster-Analyse KW - Methode Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-87288 ER - TY - JOUR A1 - Schneider, Wolfgang A1 - Scheibler, D. T1 - Probleme und Möglichkeiten bei der Bewertung von Clusteranalyse-Verfahren: III. Appendix: Kurzbeschreibung der verbreitetsten Clusteranalyse-Algorithmen T1 - On the evaluation of clustering algorithms, III. Appendix: a description of the most popular algorithms T1 - Problemeset cossibilites d'evaluation de procedes des analyses Cluster, III. Appendix: Courte description des Algorithmes analyse Cluster les plus rependues N2 - Es wird eine relativ einfach gehaltene Kurzcharakteristik derjenigen Clusteranalyse-Algorithmen gegeben, die aufgrund eines Literaturüberblicks (SCHNEIDER & SCHEIBLER 1983a) als die in der Fonchung hauptsächlich benutzten Verfahren einzustufen sind. Die Kurzbeschreibung verzichtet im wesentlichen auf statistische Details und verfolgt speziell das Ziel, dem Leser eine Vorstellung von Gemeinsamkeiten und Untenchieden in der Funktionsweise von hierarchischen Clusteranalysen, Optimierungs- bzw. Partitionierungstechniken, Dichteverfahren, "Clumping Techniques" und anderen Prozeduren zu geben. N2 - This paper presents a summary of 18 clustering algorithms most frequently applied in reseuch (cf. SCHNEIDER & SCHEIBLEK 1983a). Only a short description of each procedure is provided which aims at highlighting the basic differences and comrnonalities of hierarchical clustering algorithms, iterative partitioning methods, mode seeking techniques, clumping techniques, and other procedures. N2 - Les Algorithmes analyse Cluster qui sont decritent par (Schneider & Scheibler 1983) comme etant les procedes les plus rependus dans Ia recherche sont relates ici de facon courte. Le description chematique exclue l'ennumeration des details statistiques et a pour but essentiel de transmettre au lecteur, entre autre, une representation des rapports et des differences dans Je mode de fonction des analyses Cluster hierarchiques, des techniques d'optimation, et des procedes de population «Clumping techniques» etc. KW - Cluster-Analyse Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69643 ER - TY - JOUR A1 - Schneider, Wolfgang A1 - Scheibler, D. T1 - Probleme und Möglichkeiten bei der Bewertung von Clusteranalyse-Verfahren: II. Ergebnisse einer Monte-Carlo-Studie T1 - On the evaluation of clustering algorithms: A Monte Carlo approach T1 - Probleme et possibilite pour l'evaluation des procedes l'analyse de cluster N2 - Ziel der vorliegenden Untersuchung war es, Aufschluß über die unterschiedliche Qualität hierarchischer und nicht-hierarchischer (partionierender) Clusteranalyseverfahren zu gewinnen. Die Reproduktionsgüte beider Clusteranalyse-Varianten wurde anhand von 200 Monte-Carlo-Datensätzen (multivariat normalverteilte Mixturen) zu überprüfen versucht, wobei jeweils unterschiedliche Proportionen der Daten-Elemente klassifiZiert werden mußten. Es zeigte sich, daß insgesamt gesehen die hierarchischen Algorithmen nach WARD und LANCE-WILUAMS am besten dazu in der Lage waren, die vorgegebenen Datenstrukturen zu reproduzieren, andererseits aber die herangezogenen partitionierenden KMEANS-Verfahren nicht schlechter abschnitten, wenn die Lösung der WARD-Technik als Start-Partition vorgegeben wurde. N2 - In this study, a number of hierarchical dustering algorithms and nonhierarchical (i.e. iterative-partitioning) methods were compared with regard to accuracy on the basis of 200 monte carlo data sets. As main results, the two hierarchical procedures by WARD and LANCE-WILUAMS as weil as two nonhierarchicallc-means algorithm using WARDs solution as starting seeds proved tobe most robust. Although some of the remaining algorithms showed acceptabel recovery values when only a certain proportion of the elements had to be classified, it is recommended to choose the few methods mentioned above for particular applications. N2 - Le but de cette etude est d'obtenir des renseignements sur les differentes qualitees hierarchiques et non-hierarchiques (partionaires) procedes d'analyse de Clusters. Le qualite de reproduction des deux variantes d'analyse de Cluster a ete relevee et controlee a l'aide de 200 groupes de Monte-Cario (multivariation, melange de distribution normale). Pour chacune des proportions differentes, les elements de donnees ont du etre classes. On observe, dans l'ensemble, que l'algorithme hierarchique selon Ward etLance-Williams, est en mesure de reproduire, le mieux, les structures de donnees impliquees. D'autre part, les procedes appliques de KMEANS-partionaires ne se detachent pas pour le moins de ces resultats lorsque Ia solution de Ia technique de Ward a été, au prealablement, donnée comme situation de depart. KW - Monte-Carlo-Simulation KW - Cluster-Analyse Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69637 ER - TY - JOUR A1 - Wilhelm, Gernot A1 - Meyer, Jan-Waalke T1 - Eine spätbronzezeitliche Keilschrifturkunde aus Syrien (Tafeln 58a-59), 1. Der Text N2 - No Abstract available KW - Damaskus KW - Archäologie KW - Zeitschrift Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-85762 ER - TY - JOUR A1 - Viebrock, A A1 - Perz, A A1 - Sebald, Walter T1 - Molecular cloning of middle-abundant mRNAs from Neurospora crassa N2 - no abstract available KW - Neurospora crassa Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-82033 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Bentlage, Anke A1 - Towart, Robertson A1 - Möller, Eike T1 - Sila-pharmaca, XXV. Sila-analogues of nifedipine-like dialkyl 2,6-dimethyl-4-aryl-1,4 dihydropyridine-3,5-dicarboxylates, III N2 - IS neue C/Si-Analogenpaare (C-Verbindungen und sila- bzw. disila-substituierte Derivate), die sich strukturell vom Nifedipin ableiten, wurden synthetisiert. Diese und einige weitere C/Si-Paare wurden hinsichtlich ihrer physikochemischen und pharmakologischen Eigenschaften vergleichend untersucht. Mittels reversed-phase-Dünnschichtchromatographie wurde gezeigt, daß die Sila- bzw. Disila-Analoga lipophiler sind als die entsprechenden C-Verbindungen. Bezüglich der spasmolytischen in vitra-Aktivitäten zeigen die Si-Verbindungen in erster Näherung ähnliche Struktur-Wirkungs-Beziehungen wie ihre Carba-Analoga. Dagegen konnten hinsichtlich der ill vlva-Effekte (cardiovasculäre und antihypertensive Aktivität) in einigen Fällen große Unterschiede nachgewiesen werden. N2 - 15 new C/Si-analogue pairs (C-compounds and sila- or disila-substituted derivatives, respectively), which are structurally related to nifedipine, have been synthesized. These and some further C/Si-pairs have been investigated comparatively with respect to their physicochemical and pharmacological properties. Using reversed-phase thin-layer chromatography it was shown that both the sila- and disila-analogues are more Iipophilic than the corresponding C-compounds. With respect to the in vitra spasmolytic potencies the Si-compounds show approximately similar structure-activity relationships to their carba-analogues. However, in some cases marked differences in in vivo effects (cardiovascular and antihypertensive activity) could be demonstrated. KW - Anorganische Chemie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-78357 ER - TY - JOUR A1 - Hoppe, J. A1 - Friedl, P. A1 - Schairer, H. U. A1 - Sebald, Walter A1 - Meyenburg, K. von A1 - Jorgensen, B. B. T1 - The topology of the proton translocating F\(_0\) component of the ATP synthase from E. coli K12: studies with proteases N2 - The accessibility of the three F\(_0\) subunits a, b and c from the Escherichia coli Kll A TP synthase to various proteases was studied in F\(_1\)-depleted inverted membrane vesicles. Subunit b was very sensitive to all applied proteases. Chymotrypsin produced a defined fragment of mol. wt. 1S 000 which remained tightly bound to the membrane. The cleavage site was located at the C-terminal region of subunit b. Larger amounts of proteases were necessary to attack subunit a (mol. wt. 30 000). There was no detectable deavage of subunit c. It is suggested that the major hydrophilic part of subunit b extends from the membrane into the cytoplasm and is in contact with the F\(_1\) sector. The F\(_1\) sector was found to afford some protection against proteolysis oftheb subunit in vitro andin vivo. Protease digestion bad no influence on the electro-impelled H\(^+\) conduction via F\(_0\) bot ATP-dependent H\(^+\) translocation could not be reconstituted upon binding of F\(_1\)• A possible role for subunit b as a linker between catalytic events on the F\(_1\) component and the proton pathway across the membrane is discussed. KW - Biochemie KW - protein pathway KW - ATPase mutants Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-62718 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Lange, H. T1 - Thermisch induzierte Umlagerung von (Acyloxymethyl)- diorganylsilanen T1 - Thermally Induced Rearrangement of (Acyloxymethyl)diorganylsilanes N2 - Die (Acyloxymethyl)diorganylsilane R\(^1\)R\(^2\)Si(H)CH\(_2\)OC(O)R\(^3\) (2a- d) unterliegen einer thermisch induzierten Umlagerung zu den entsprechenden Acyloxy(methyl)diorganylsilanen R\(^1\)R\(^2\)Si(CH\(_3\))OC(O)R\(^3\) (3a- d). Diese Reaktion beinhaltet formal einen Austausch des am Silicium gebundenen Wasserstoffs mit dem am Kohlenstoff gebundenen Acyloxy-Rest. Bezüglich der 1,2- Wasserstoff-Verschiebung konnte experimentell ein intramolekularer Prozeß bewiesen werden. N2 - The (acyloxymethyl)diorganylsilanes R\(^1\)R\(^2\)Si(H)CH\(_2\)OC(O)R\(^3\) (2a-d) rearrange to the corresponding acyloxy(methyl)diorganylsilanes R\(^1\)R\(^2\)Si(CH\(_3\))OC(O)R\(^3\) (3a-d). This reaction is formally equivalent to an exchange of the hydrogen bound to silicon and the acyloxy group bound to carbon. The 1 ,2-hydrogen shift could be shown experimentally to be an intramolecular process. KW - Anorganische Chemie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63752 ER - TY - JOUR A1 - Tacke, Reinhold A1 - Strecker, M. A1 - Lambrecht, G. A1 - Moser, U. A1 - Mutschler, E. T1 - (2-Aminoethyl)-cycloalkylphenylsilanole: Bioisosterer C/Si-Austausch bei Parasympatholytika vom Typ des Trihexyphenidyls, Cycrimins und Procyclidins T1 - (2-Aminoethyl)cycloalkylphenylsilanols: Bioisosteric C/Si Exchange in Parasympatholy1ics of lhe Trihexyphenidyl, Cycrimine, and Procyclidine Type N2 - Die Synthese der (2-Aminoethyl)cycloalkylphenylsilanole Sb (Sila-Trihexyphenidyl), 6b (SilaCycrimin), 7 b (Sila-Procyclidin) und Sb wird beschrieben. Sb- Sb wurden - ausgehend von Cl\(_2\)(C\(_6\)H\(_5\))SiCH = CH\(_2\) (9) - durch eine fünfstufige Reaktionsfolge mit einer Gesamtausbeute von 32- 40% erhalten. Am isolierten Ileum des Meerschweinchens wurden die C/Si-Paare Sa, b- 8a, b vergleichend auf ihre antimuskarinische Aktivität geprüft. Die durch die Sila-Substilution von Sa-8a erreichte Zunahme der Affinität zum Muskarinrezeptor ist deutlich weniger ausgeprägt als bei den strukturverwandten C/Si-Paaren I a, b- 4a, b. N2 - Thc synthesis of thc (2-aminoethyl)cycloalkylphenylsilanols Sb (sila-trihexyphenidyl), 6b (silacycrimine), 7b (sila-procyclidine), and Sb is described. Starting with Cl2(C6H5)SiCH = CH2 (9), Sb- 8 b were obtained by five reaction steps with a total yield of 32- 40%. The C/Si pairs Sa,b- 8a, b were tested for antimuscarinic activity on the isolated guinea-pig ileum. Thc increase of affinity for the muscarinic reccptor caused by sila-substitution of S a- 8a is less marked than in the case of the structurally related C/Si pairs la,b-4a,b. KW - Anorganische Chemie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-63741 ER - TY - JOUR A1 - Meier-Bratschi, A. A1 - Lutz, Werner K. A1 - Schlatter, C. T1 - Methylation of liver DNA of rat and mouse by N-nitrosodimethylamine formed in vivo from dimethylamine and nitrite N2 - The extent of formation of N-nitrosodimethylaminc {NDMA) in the stomachs of rats and mice after sirnultancous oral administration of [\(^{14}\)C]dimethylamine and potassium nitrite was determined by measuring the methylation of liver DNA. With doses of around 1 mg dimethylamine hydrochloride/ kg body weight and 50 mg potassium nitrite/kg body weight. 0,8 % of the amine was nitrosated on average. The individual fluctuations ranged from 0.2 to 1.30% in the rat and from 0.2 to 1.9% in the mouse. Simultaneous administration of 50 mg sodium ascorbate (vitamin Cl/kg body weight inhibited the nitrosation by ahout 80% while 50 mg \(\alpha\)-tocopherol acetate [Vitamin E)/kg body weight reduced the nitrosation by about a half. Assuming similar kinctics and conditions of nitrosation in rats and man. a comparison of the formation of NDMA in vivo from dietary dimethylamine and nitrite with the estimated human uptake of preformed N DMA revealed that in vitro formation in the stomach of man is probably negligible. KW - Toxikologie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61052 ER - TY - JOUR A1 - Jauch, A. A1 - Lutz, Werner K. T1 - In vivo assay for somatic point mutations induced by genotoxic carcinogens: incorporation of [\(^{35}\)S]methionine into a rat liver cytochrome b\(_5\) normally lacking sulphur-containing amino acids N2 - The trypsin fragments of rat liver microsomal cytochron1e b\(_5\) (Tb\(_5\)) lack both methionine (met) and cysteine (cys), i.e., the sulphur-containing antino acids. Tb\(_5\) should therefore contain no 358-radioactivity after isolation from animals treated wHh [\(^{35}\)S]met or [\(^{36}\)S]cys. If, however, the nucleic acids coding for this polypeptide have been damaged by a genotoxic carcinogen, a miscoding could result in an incorporation of met or cys into the polypeptide so that Tb\(_8\) could now be \(^{36}\)S-radiolabelled. Two experiments are descrihed. the first one where a toxic regimen of N -nitrosomorpholine (NNM) to rats resulted in a significant increase of \(^{35}\)S-radioactivity in the Tbs of liver microsomes, and a second experiment with a non-toxic regimen of N,N diethylnitrosamine (DENA), where no increase was observable. KW - Toxikologie KW - MammaJian mutagenicity test KW - Pointmutation KW - Protein coding KW - Cytochrome b5 KW - Amino acid composition KW - Rat Iiver microsomes Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61047 ER - TY - JOUR A1 - Sagelsdorff, P. A1 - Lutz, Werner K. A1 - Schlatter, C. T1 - The relevance of covalent binding to mouse liver DNA to the carcinogenic action of hexachlorocyclohexane isomers N2 - [\(^3\)H]Hexachlorocyclohexane (HCH) was synthesized by chlorination of [\(^3\)H]benzene prepared by catalytic tritiation of benzene with tritiated water. The isomers of HCH were separated by adsorption chromatography on silica gel. In order to determine the covalent binding to DNA, [\(^3\)H]HCH was administered to male mice by oral gavage, and liver DNA was isolated via cbromatin. The specific radioactivity of the DNA was nonnalized by the dose administered and expressed in the molar units of the Covalent binding index, CBI = DNA damage/dose = (\(\mu\)mol bound HCH/mol DNA nucleotide)/(mmol HCH administered/kg body weight). CBI values of - 0.2 were found 10 h after the administration of alpha- and gamma-HCH. Enzymatic digestion of the DNA to the nucleosides and h.p.l.c. analysis revealed that - 40% of the radioactivity co-migrated with the natural nucleosides. At elution volumes known to contain the more lipophilic carcinogen-nucleoside adducts, - 10% of the radioactivity could be detected. The remaining 50% of th,e radioactivity eluted with the front, representing a mixture of oligonucleotide- HCH adducts and/or hydrophilic degradation products which were strongly bot not covalently associated with intact DNA. Therefore, a true CBI of 0.02-0.1 must be expected both for alpha- and gamma-HCH. This CBI is by a factor of 10\(^5\) -10\(^6\) below the value found with the strongest DNAbinding carcinogens like aflatoxin B1 or dimethylnitrosamine and is unlikely to be decisive for the liver tumor induction in mice because of the foUowing additional findings: (i) both isomers gave rise to similar Ievels of DNA darnage although the alpha-isomer is a much morepotent tumor inducer. This similarity was seen not only at the time of mäximum binding but up to 10 days after oral administration; (ii) three mouse strains with apparently different susceptibility to tumor induction by gamma-HCH could not be distinguished with respect to DNA binding; (iii) the level of DNA binding of alpha-HCH (CBI = 0.02-0.1) is more than three orders of magnitude lower than would be expected if the mechanism of tumor induction was by genotoxicity mediated by DNAbinding. For a preliminary investigation on a potential stimulatory effect on liver DN A replication and ceU division, [\(^{14}\)]thymidine was admlnistered i.p. 3.5 h before sacrifice of the [\(^3\)H]HCH-treated mice. The alpha-isomer was found to be more potent than the gamma-isomer in this respect. Taken together, our data allow the conclusion that the non- mutational processes must be more important for the carcinogenicity of HCH. KW - Toxikologie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-61039 ER - TY - JOUR A1 - Hughes, C. A1 - Hacker, Jörg A1 - Roberts, A. A1 - Goebel, W T1 - Hemolysin production as a virulence marker in symptomatic and asymptomatic urinary tract infections caused by Escherichia coli N2 - Potential virulence, as defined by combined Ievels of adhesion to urinary epithelial cells, serum resistance, and mouse toxicity, was assessed for Escherichia coli strains causing symptomatic and asymptomatic urinary tract infections in relation to the carriage of hemolysin and other suspected virulence determinants. Hemolysin production (Hly), associated with certain 0 (04, 06, 018, and 075), K (5), and hemagglutination (VI and VII) antigenic types but not colicin V production (Cva), was evident in 83 and 60% ofisolates in groups possessing high potential virulence andin only 11 and 6% of those with low virulence. Strains of particular 0-types were not more virulent per se, but among the serotypes, specific combinations of virulence factors appeared decisive, e.g., 018 HAVI B/D/G Hly+ K5+t- and 018 HAIIIIIVBN Hly- Cva +t- Kl +t- strains were, respectively, of high and low potential virulence. Isolates with high potential virulence were found to a similar extent in symptomatic and asymptomatic infections. KW - Infektionsbiologie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59346 ER - TY - JOUR A1 - Hacker, Jörg A1 - Hughes, C. A1 - Hof, H. A1 - Goebel, W. T1 - Cloned hemolysin genes from Escherichia coli that cause urinary tract infection determine different levels of toxicity in mice N2 - After intraperitoneal injection of mice with Escherichia coli strains isolated from patients with urinary tract infections, the mortality due to hemolytic (Hly+) and nonhemolytic (Hiy-) isolates was 77 and 40%, respectively. Deletion of the chromosomal hemolysin (h/y) determinant in an E. co/i 06:K15:H31 urinary tract infection strain led to a significant reduction in toxicity for mice, and its reintroduction on a recombinant plasmid partially restored the original toxicity. Although introduction of the cloned plasmid pHiy152-encoded hly determinant into the Hly- E. coli 06 mutant strain increased toxicity by only a marginal degree, transformation with the cloned chromosomal hly determinants from two E. coli strains of serotypes 018ac:K5:H- and 075:K95:H? resulted in markedly greater toxicity, even exceeding that of the original Hly+ E. coli 06 wild-type strain. KW - Infektionsbiologie Y1 - 1983 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59330 ER -