TY  - JOUR
A1  - Tacke, Reinhold
A1  - Wagner, S. A.
A1  - Sperlich, J.
T1  - Synthese von (-)-(Acetoxymethyl)(hydroxy-methyl)methyl(phenyl)german [(-)-MePhGe(CH\(_2\)OAc)(CH\(_2\)OH)] durch eine Esterase-katalysierte Umesterung: Die erste enzymatische Synthese eines optisch aktiven Germans
N2  - No abstract available.
KW  - Anorganische Chemie
KW  - Germane
KW  - optically active
KW  - Biotransformation
KW  - stereoselective Transesterification
KW  - enzymatic
KW  - Porcine liver esterase
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64310
ER  - 
TY  - JOUR
A1  - Tacke, Reinhold
A1  - Pikies, J.
A1  - Wiesenberger, F.
A1  - Ernst, L.
A1  - Schomburg, D.
A1  - Waelbroeck, M.
A1  - Christophe, J.
A1  - Lambrecht, G.
A1  - Gross, J.
A1  - Mutschler, E.
T1  - Sila-biperiden und endo-Sila-biperiden: Synthesen, Kristallstrukturen und antimuscarinische Eigenschaften
N2  - Starting from trichloro(vinyl)silane (Cl\(_3\)SiCH=CH\(_2\)), the musearinic antagonists sila-biperiden [rac-(SiRS,C2SR>-ao-2] and endosila- biperiden [rac-(SiRS,C2SR)-endo-2] were prepared by a seven-step synthesis. Both silanols are configurationally stableininert organic solvents but undergo slow epimerization in aqueous solution (pH 7.4, 32°C) by inversion of the configuration at the silicon atom. The relative configurations of sila-biperiden and endo-sila-biperiden were detennined by single-crystal X-ray diffraction. Both compounds form intennolecular 0-H · · · N hydrogen bonds in the crystal leading to the fonnation of centrosymmetric dimers (sila-biperiden) and infinite chains (endo-sila-biperiden), respectively. Sila-biperiden is a silicon analogue (C/Si exchange) of the antiparkinsonian drug biperiden [rac-(CRS/C2SR}-exo-1]. In functional phannacological experiments, as well as in radioligand competition studies, biperiden, sila-biperiden and endo-sila-biperiden behaved as simple competitive antagonists at muscarinic Ml-, M2-, M3- and M4-receptors. The three compounds displayed the highest affinity for Ml-receptors (pA\(_2\) values: 8.72-8.80; pK\(_i\) values: 8.8-9.1), intermediate affinity for M4- and M3-receptors, and lowest affinity for M2-receptors (pA\(_2\) values: 7.57-7.79; pK\(_i\) values: 7.7-7.8). The affinity profile (Ml >. M4 > M3 > M2) of biperiden, sila-biperiden and endo-sila-biperiden is qualitatively similar to that of the M1-selective muscarinic antagonist pirenzepine. The antimuscarinic properlies of the C/Si analogues biperiden and sila-biperiden are almost identical.
N2  - Die Antimuscarinica Sila-biperiden [rac-(SiRS,C2SR)-exo-2] und endo-Sila-biperiden [rac-(SiRS,C2SR)-endo-2] wurden ausgehend von Trichlor(vinyl)silan (Cl\(_3\)SiCH=CH\(_2\)) durch eine siebenstufige Synthese dargestellt. Die beiden Silanoie sind in inerten organischen Solvenzien konfigurationsstabil, unterliegen aber in wässeriger Lösung (pH 7.4, 3ZOC) einer Epimerisierung durch Inversion der Konfiguration am Silicium-Atom. Die relativen Konfigurationen von Sila-biperiden und endo-Sila-biperiden wurden durch Einkristall-Röntgenstrukturanalysen bestimmt. Beide Verbindungen bilden im Kristall intermolekulare 0-H · · · N-Wasserstoff- Brückenbindungen aus, die zum Aufbau von zentrosymmetrischen Dimeren (Sila-biperiden) bzw. unendlichen Ketten (endo-Sila-biperiden) führen. Sila-biperiden ist ein Silicium-Analogon (C/Si-Austausch) des Antiparkinsonmittels Biperiden [rac-(CRS,C2SR>-ao-1). Sowohl in funktionellen pharmakologischen Untersuchungen als auch in Radioligand-Kompetitionsexperimenten erwiesen sich Biperiden, Sila-biperiden und endo-Sila-biperiden als rein kompetitive Antagonisten an muscarinischen M1-, M2-, M3- und M4-Rezeptoren. Alle drei Verbindungen zeigten die höchste Affinität zu den Mt-Rezeptoren (pA\(_2\)-Werte: 8.72-8.80; pKrWerte: 8.8-9.1), eine deutlich geringere Affinität zu den M4- und M3-Rezeptoren und die niedrigste Affinität zu den kardialen M2-Rezeptoren (pA\(_2\)-Werte: 7.57-7.79; pKi-Werte: 7.7-7.8). Das Affinitätsprofil (Ml > M4 > M3 > M2) von Biperiden, Sila-biperiden und endo-Sila-biperiden ist dem des Mt-selektiven Antimuscarinicums Pirenzepin qualitativ sehr ähnlich. Die antimuscarinischen Eigenschaften der C/Si-Analoga Biperiden und Sila-biperiden sind nahezu identisch.
KW  - Anorganische Chemie
KW  - Silicon
KW  - Silanol
KW  - Sila-biperiden
KW  - Bioorganosilicon chemistry
KW  - Muscarinic antagonist
KW  - Muscarinic receptor subtype
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-64303
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Dolg, Michael
A1  - Stoll, Hermann
A1  - Schnering, Hans Georg von
T1  - Oxidation State +IV in Group 12 Chemistry : Ab Initio Study of Zinc(IV), Cadmium(IV), and Mercury(IV) Fluorides
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60018
ER  - 
TY  - JOUR
A1  - Wissing, Elmo
A1  - Kaupp, Martin
A1  - Boersma, Jaap
A1  - Spek, Anthony L.
A1  - Koten, Gerard van
T1  - Alkylation Reactions of Dialkylzinc Compounds with 1,4- Diaza- 1,3-butadienes: Cationic and radical Anionic Organozinc Intermediates. Molecular Structure of the Cationic Organozinc Species [MeZn(t-BuN=CHCH=N-t-Bu)]O\(_3\)SCF\(_3\) and Me\(_2\)Zn(bpy)(bpy = 2,2' -Bipyridine)
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60008
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Schnering, Hans Georg von
T1  - The Dominance of Linear 2-Coordination in Mercury Chemistry: Quasirelativistic and Nonrelativistic ab Initio Pseudopotential Study of (HgX\(_2\))\(_2\) (X=F, Cl, Br, I, H)
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59995
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Schnering, Hans Georg von
T1  - Origin of the Unique Stability of Condensed-Phase Hg\(_2 ^{2+}\). An ab Initio Investigation of M\(^I\) and M\(^{II}\) Species (M= Zn, Cd, Hg)
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59981
ER  - 
TY  - JOUR
A1  - Grunicke, H.
A1  - Pyerin, W.
A1  - Eisenbrand, G.
A1  - Havemann, K.
A1  - Rabes, H. M.
A1  - Molling, K.
A1  - Schwab, M.
A1  - Lutz, Werner K.
A1  - Wahrendorf, J.
A1  - Schirrmacher, V.
T1  - 7th International Symposium of the Division of Experimental Cancer Research (AEK) of the German Cancer Society : [Meeting report]
N2  - No abstract available
KW  - Toxikologie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60651
ER  - 
TY  - JOUR
A1  - Fischer, W. H.
A1  - Lutz, Werner K.
T1  - Short communication : Mouse skin papilloma formation by chronic dermal application of 7,12-dimethylbenz[a]anthracene is not reduced by diet restriction
N2  - No abstract available
KW  - Toxikologie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60644
ER  - 
TY  - JOUR
A1  - Shephard, S. E.
A1  - Lutz, Werner K.
A1  - Schlatter, C.
T1  - The lacI transgenic mouse mutagenicity assay: quantitative evaluation in comparison to tests for carcinogenicity and cytogenetic damage in vivo
N2  - The detection Iimit of the lacl transgenic mouse mutagenicity assay lies, in practice, at approximately a 50-100% increase in mutant frequency in treated animals over controls. The sensitivity of this assay in detecting genotoxins can be markedly improved by subchronic rather than acute application of the test compound. The lac/ transgenic mouse mutagenicity assay was compared quantitatively to rodent carcinogenicity tests and to presently used in vivo mutagenicity assays. With the genotoxic carcinogens tested thus far, a rough correlation between mutagenic potency and carcinogenic potency was observed: on average, to obtain a doubling in lacl mutant frequency the mice bad to be treated with a total dose equal to 50 times the TD50 daily dose Ievel. This total dose could be administered eilher at a high dose rate within a few days or, preferably, at a low dose rate over several weeks. This analysis also indicated that a lacl experiment using a 250-day exposure period would give a detection Iimit approximately equal to that of a long-term carcinogenicity study. In comparison to the micronucleus test or the chromosome aberration assay, acute sturlies with the presently available lacl system offered no increase in sensitivity. However, subchronic lacl sturlies (3-4-month exposure) resulted in an increase in sensitivity over the established tests by 1-2 orders of magnitude (shown with 2-acetylaminofluorene, N-nitrosomethylamine, N-nitrosomethylurea and urethane). 1t is concluded that a positive result in the lacl test can be highly predictive of carcinogenicity butthat a negative result does not provide a large margin of safety.
KW  - Toxikologie
KW  - Transgenie mice
KW  - Mutagenicity assay
KW  - Sensitivity
KW  - Chromosome aberration
KW  - Micronucleus test
KW  - Carcinogenic potency
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-60638
ER  - 
TY  - JOUR
A1  - Kaupp, Martin
A1  - Schnering, Hans Georg von
T1  - Ab Initio Comparision of the (MX\(_2\))\(_2\) Dimers (m=Zn, Cd, Hg; X F, Cl, H), and Study of Relativistic Effects in Crystalline HgF\(_2\)
N2  - No abstract available
KW  - Anorganische Chemie
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-59971
ER  -