@phdthesis{Kalb2005, author = {Kalb, Stefanie}, title = {Wilhelm Neumann (1898 - 1965) - Leben und Werk unter besonderer Ber{\"u}cksichtigung seiner Rolle in der Kampfstoff-Forschung}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16124}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {Gegenstand der vorliegenden Untersuchung ist das Leben und Werk des deutschen Pharmakologen und Toxikologen Wilhelm Neumann (11. Februar 1898 - 15. April 1965). Wesentliche Erkenntnisse hierzu konnten aus Aktenbest{\"a}nden des Bundesarchivs der Bundesrepublik Deutschland in Berlin-Lichterfelde, Freiburg im Breisgau, und Koblenz, des Dekanatsarchiv der Medizinischen Fakult{\"a}t der Bayerischen Julius-Maximilians-Universit{\"a}t W{\"u}rzburg, des Archivs der „Deutschen Gesellschaft f{\"u}r experimentelle und klinische Pharmakologie und Toxikologie" in Mainz, des Scheringianums, dem Archiv der Schering AG in Berlin, des Staatsarchivs W{\"u}rzburg und des Universit{\"a}tsarchivs der Bayerischen Julius-Maximilians-Universit{\"a}t W{\"u}rzburg gewonnen werden. Von 1919 bis 1923 studierte Wilhelm Neumann in Berlin Chemie und promovierte in der chemischen Abteilung des Preußischen Instituts f{\"u}r Infektionskrankheiten „Robert Koch" zum Dr. phil. Im Jahr 1924 trat er eine Stelle als Privatassistent am Pharmakologischen Institut der Universit{\"a}t W{\"u}rzburg unter der Leitung Ferdinand Flurys an. Parallel zu seiner Arbeit am Pharmakologischen Institut studierte er von 1929 bis 1934 an der Universit{\"a}t W{\"u}rzburg Humanmedizin und promovierte zum Dr. med. 1937 folgte seine Habilitation und die Ernennung zum Dozenten. Weitere Stationen seiner wissenschaftlichen Laufbahn am Pharmakologischen Institut waren die Ernennungen zum planm{\"a}ßigen Assistenten 1939, zum Konservator 1941 und zum außerplanm{\"a}ßigen Professor 1942. Im Jahr 1937 nahm Wilhelm Neumann als Arzt der Reserve seine milit{\"a}rische Karriere im Sanit{\"a}tsdienst der Wehrmacht auf. W{\"a}hrend des Zweiten Weltkrieges war er als „beratender Arzt" und als Wissenschaftler f{\"u}r die Wehrmacht t{\"a}tig. Neumanns politischer Werdegang begann im Juli 1933 mit seinem Beitritt zur Veteranenorganisation Stahlhelm. Im Februar 1934 wurde er Mitglied der SA, und ab dem 1. Mai 1937 geh{\"o}rte er der NSDAP an. Nach Ende des Zweiten Weltkrieges wurde Neumann im Zuge des Entnazifizierungsprozesses 1946 aus dem Staatsdienst entlassen. Das 1947 ergangene Spruchkammerurteil reihte ihn in die Gruppe der „Mitl{\"a}ufer" ein. Infolgedessen konnte er 1948 wieder von der Universit{\"a}t W{\"u}rzburg eingestellt werden. Im Jahr 1949 wurde er dort zum ordentlichen Professor f{\"u}r Pharmakologie und Toxikologie berufen. Von 1954 bis 1955 {\"u}bte er das Amt des Dekans der Medizinischen Fakult{\"a}t der Universit{\"a}t W{\"u}rzburg aus. Am Pharmakologischen Institut der Universit{\"a}t W{\"u}rzburg untersuchte Neumann zun{\"a}chst die Chemie und Pharmakologie der herzwirksamen Glykoside. Ihm gelang auf diesem Gebiet die Reindarstellung eines neuen Wirkstoffs, der 1935 von der Firma Schering im Herzinsuffizienztherapeutikum Folinerin auf den Markt gebracht wurde. Auf toxikologischem Gebiet arbeitete er von 1925 bis 1945 mit Ferdinand Flury an gewerbetoxikologischen Projekten und in der chemischen Kampfstoff-Forschung. Als ordentlicher Professor widmete sich Wilhelm Neumann dann neben eigenen toxikologischen Arbeiten der F{\"o}rderung der Toxikologie als Fachrichtung. Zu Beginn der 1950er Jahre befasste er sich mit tierischen Giften und erforschte die Toxikologie der Reizgase und der Luftverschmutzung. Von 1955 bis 1965 war Wilhelm Neumann Vorsitzender der DFG-Kommission zur Pr{\"u}fung gesundheitssch{\"a}dlicher Arbeitsstoffe.}, language = {de} } @article{LutzDeuberCaviezeletal.1988, author = {Lutz, Werner K. and Deuber, R. and Caviezel, M. and Sagelsdorff, P. and Friederich, U. and Schlatter, C.}, title = {Trenbolone growth promotant: covalent DNA binding in rat liver and in Salmonella typhimurium, and mutagenicity in the Ames test}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60897}, year = {1988}, abstract = {DNA binding in vivo: (6,7-\(^3\)H]ß-trenbolone (ß-TBOH) was administered p.o. and i.p. to rats. After 8 or 16 h, DNA was isolated from the livers and purified to constant specific radioactivity. Enzymatic digestion to deoxyribonucleotides and separation by HPLC revealed about 90\% ofthe DNA radioactivity eluting in the form of possible TBOH-nucleotide adducts. The extent of this genotoxicity, expressed in units of the Covalent Binding Index, CBI = (~mol TBOH bound per mol nucleotide)/(mmol TBOH administered per kg body weight) spanned from 8 t~ 17, i. e. was in the range found with weak genotoxic carcmogens. Ames test: low doses of ß-TBOH increased the number of revertants in Salmonella strain TAl 00 reproducibly and m a dose-dependent manner. The mutagenic potency was 0.2 revertants per nmol after preincubation of the bacteria (20 min at 37° C) with doses between 30 and 60 \(\mu\)g per plate (47 and 94 \(\mu\)g/ml preincubation mixture). Above this dose, the number of revertants decreased to control values, accompanied by a reduction in survival. The addition of rat liver S9 inhibited the mutagenicity. DNA binding in vitro: calf thymus DNA was incubated with tritiated ß-TBOH with and without rat liver S9 Highest DNA radioactivities were determined in the absence of the "activation" system. Addition of inactive S9 (without cofactors) reduced the DNA binding by a factor of up to 20. Intermediate results were found with active S9. DNA binding in Salmonella: ß-TBOH was irreversibly bound to DNA isolated from S. typhimurium TA100 after incubation of bacteria with [\(^3\)H]ß-TBOH. Conclusions: Covalent DNA binding appears to be the mechanism of an activation-independent ("direct") mutagenicity of TBOH which is not easily detected because of the bactericidal activity. The genotoxicity risk arising from exposure of humans to trenbolone residues in meat was estimated using the in vivo data and compared to that from the exposure to unavoidable genotoxins aflatoxin B1 and dimethylnitrosamine. It ts concluded that trenbolone residues represent only a low genotoxic risk.}, subject = {Toxikologie}, language = {en} } @phdthesis{Troesken2005, author = {Tr{\"o}sken, Eva-Regina}, title = {Toxicological evaluation of azole fungicides in agriculture and food chemistry}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-17016}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {Azole sind wichtige Chemikalien, die als Fungizide in der Landwirtschaft und der Medizin eingesetzt werden. Auch als Zytostatika in der Humanmedizin finden sie Anwendung. Die fungizide Wirkung beruht auf der Hemmung der Lanosterol-14\&\#945;-Demethylase (CYP51), die die Demethylierung von Lanosterol zum „Follicular Fluid Meiosis Activating Steroid (FF-MAS)" katalysiert. F{\"u}r Pilze ist das sp{\"a}ter resultierende Ergosterol ein essentieller Bestandteil der Zellmembran. Exponierten Pilzen fehlt Ergosterol was zu einem Zusammenbruch der Zellmembran f{\"u}hrt. S{\"a}ugetiere k{\"o}nnen Cholesterol, das sp{\"a}tere Produkt der Lanosterol-14\&\#945;-Demethylierung, das zur Synthese von z.B. Gallens{\"a}uren und Sexualhormonen n{\"o}tig ist, mit der Nahrung aufnehmen. FF-MAS und das resultierende T-MAS (Testis Meiosis Activating Steroids), die direkten Produkte der CYP51 katalysierten Reaktion, wirken als Meiose-aktivierende Steroide auf Ovarien und Hoden und werden nicht mit der Nahrung aufgenommen. Eine Hemmung der CYP51 Aktivit{\"a}t k{\"o}nnte das endokrine System beeinflussen und wird daher als unerw{\"u}nschte Nebenwirkung der Azole betrachtet. Aromatase (CYP19) katalysiert die Demethylierung von Testosteron zu {\"O}stradiol und wird durch Azole gehemmt. Die Verringerung der {\"O}strogenspiegel durch CYP19-Inhibition ist das Wirkprinzip der als Zytostatika genutzten Azole, bei den Fungiziden wird es als unerw{\"u}nschte Nebenwirkung angesehen. Ein ideales Azol sollte Pilz-CYP51 stark inhibieren, aber sowohl humanes CYP19 wie auch humanes CYP51 sollten durch ein solches Azol nicht inhibiert werden. Ein ideales Azol-Zytostatikum sollte eine starke inhibitorische Potenz gegen{\"u}ber humanem CYP19 aufweisen, hingegen sollten humanes und Pilz-CYP51 nicht inhibiert werden. Ziel dieser Arbeit war es nun festzustellen: sind Fungizide und Antimykotika starke Inhibitoren von Pilz-CYP51? Zeigen Fungizide und Antimykotika keine Aktivit{\"a}t gegen{\"u}ber humanem CYP19 und humanem CYP51? Sind Zytostatika starke Inhibitoren von humanem CYP19? Zeigen Zytostatika keine Aktivit{\"a}t gegen{\"u}ber humanem CYP51 und Pilz-CYP51? Die inhibitorische Potenz von 22 Azolen, aus den drei Anwendungsgebieten, wurden an vier Systemen getestet: i) an humanem CYP19 und einem fluoreszierenden Pseudosubstrat, ii) an CYP19 und Testosteron als Substrat, iii) an humanem CYP51 und iv) Candida albicans CYP51 und Lanosterol als Substrat. Die Produktbildung wurde mittels Hochdruckfl{\"u}ssigkeitschromatographie gekoppelter Tandem-Massenspektrometrie nach Photosprayionisation gemessen. Das humane CYP51 wurde von „BD Gentest Cooperation" zur Verf{\"u}gung gestellt. Ein katalytisch aktiver Enzymkomplex bestehend aus der Lanosterol-14\&\#945;-Demethylase von Candida albicans und der Oxidoreduktase von Candida tropicalis, wurde im Baculovirussystem exprimiert. Ein Vergleich der inhibitorischen Wirkst{\"a}rke der Substanzen auf menschliches CYP19 und CYP51 und Pilz-CYP51 zeigt, dass einige Azole das erw{\"u}nschte Bild zeigen. Dazu geh{\"o}ren die beiden Zytostatika Fadrozol und Letrozol, sowie Fluconazol und Itraconazol, zwei Antimykotika aus der Humanmedizin, und einige Fungizide z.B. Cyproconazol und Hexaconazol. Ein unerw{\"u}nschtes Bild zeigen z.B. Prochloraz, Bifonazol, Ketoconazol und Miconazol. Sieben Azole weisen ein gemischtes Bild an inhibitorischen Wirkst{\"a}rken auf. Um einen modellartigen Eindruck der R{\"u}ckst{\"a}nde von Azolen in Lebensmitteln zu erhalten, wurde eine auf LC-ESI-MS/MS basierende R{\"u}ckstandsanalytik f{\"u}r Azole im Wein entwickelt. Alle gefunden R{\"u}ckst{\"a}nde lagen unterhalb der beh{\"o}rdlich festgelegten R{\"u}ckstandsh{\"o}chstmengen. Um die inhibitorische Wirkung der Azole auf die verschiedenen Enzymsysteme in einem gr{\"o}ßeren Zusammenhang zu bringen, wurden die IC50 Werte mit Expositionsdaten von Bauern, maximalen Plasmaspiegeln in Patienten nach der Einnahme von Antimykotika und mit Expositionsgrenzwerten f{\"u}r die Langzeitaufnahme von Pflanzenschutzmittelr{\"u}ckst{\"a}nden („Acceptable Daily Intake Levels", ADI) verglichen. Basierend auf den dargestellten Ergebnissen k{\"o}nnen folgende Schlussfolgerungen gezogen werden. Das Risiko f{\"u}r landwirtschaftliche Arbeiter durch Exposition gegen{\"u}ber Azolfungiziden kann im Bezug auf menschliches CYP19 und CYP51 als vernachl{\"a}ssigbar eingestuft werden, wenn die entsprechenden Sicherheitsvorkehrungen getroffen werden. Im medizinischen Bereich muss grunds{\"a}tzlich der Einsatz von Bifonazol, Miconazol und Ketoconazol mit Blick auf die hohe inhibitorische Potenz gegen{\"u}ber menschlichem CYP19 und 51 kritisch betrachtet werden. Unter der Annahme, dass die ADI Werte eingehalten werden, stellen R{\"u}ckst{\"a}nde auf Lebensmitteln in Bezug auf die genannten Enzymsysteme keine Bedrohung f{\"u}r den Verbraucher da. Die Inhibition von CYP19 muss als St{\"o}rung des Hormonsystems angesehen werden. Die Bedeutung von FF-MAS und T-MAS im endokrinen System muss noch abschließend gekl{\"a}rt werden und damit auch die Frage, wie viel Bedeutung der Inhibition von menschlichem CYP51 beigemessen werden muss.}, subject = {Azole}, language = {en} } @article{VivianiLutzSchlatter1978, author = {Viviani, A. and Lutz, Werner K. and Schlatter, C.}, title = {Time course of the induction of aryl hydrocarbon hydroxylase in rat liver nuclei and microsomes by phenobarbital, 3-methylcholanthrene, 2,3,7,8-tetrachloro-dibenzo-p-dioxin, dieldrin and other inducers}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61182}, year = {1978}, abstract = {Aryl hydrocarbon hydroxylase (AHH) has been measured in male rat Jiver nucJei and microsomes after treatment of adult animals with various inducers for up to 14 days. After daily i.p. injections of 3-methylcholanthrene (MC, 20 mg/kg) the nuclear activity increased to a maximum of 600 per cent of the control activity after 4 days whereas the microsomal activity was 400 per cent of control at the same date. After 12 days, both activities equilibrated at 400 per cent. A similar time course was found after a single i.p. injection of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD, 0.01 mg/kg) with an induction to .500 and 300 per cent for nuclei and microsomes, respectiveJy. after 2 days, and to 400 per cent for both after 12 days. PhenobarbitaJ (PB) was given continuously in the drinking water (I g/1) and induced the microsomal activity to 200 per cent after 8 days and 170 per cent after 14 days. The nuclear activity was only slightly induced to a constant Ievei of 130 per cent between day 8 and 14. Dieldrin did not significantly increase the microsomal activity after daiJy i.p. injections (20 mg/kg), but the nuclear activity raised to 200 per cent after 3 days and levelled down tocontrol valuesafter 12 days. Other inducers tested were benz[a)anthracene (BA), hexachlorobenzene (HCB} and 1,1.1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT). The induction pattern with BA was similar tothat of MC, a modeJ compound for the group of cytochrome P448 inducers. The induction by HCB and DDT resembled that by PB. a typical cytochrome P450 inducer.}, subject = {Toxikologie}, language = {en} } @article{SagelsdorffLutzSchlatter1983, author = {Sagelsdorff, P. and Lutz, Werner K. and Schlatter, C.}, title = {The relevance of covalent binding to mouse liver DNA to the carcinogenic action of hexachlorocyclohexane isomers}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61039}, year = {1983}, abstract = {[\(^3\)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 m{\"a}ximum 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.}, subject = {Toxikologie}, language = {en} } @article{LutzPoetzschSchlatteretal.1991, author = {Lutz, Werner K. and Poetzsch, J. and Schlatter, J. and Schlatter, C.}, title = {The real role of risk assessment in cancer risk management}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60730}, year = {1991}, abstract = {Rtgulatory aclio11s Iaken to reduu tht risk of harmfultffects of exposure to chemieals ofltn arenot commensurDtt with the toxicologicDf risk SJsstS\&ment. A numbtr of factors relating to psychology, sociology, economics Dntl politics rather than science and medicine afftct tht final decision. Wemer Lutz and colleagues illustratt the situation using tht feuktmia-indudng chtmiCJJI benzene as an examplt.}, subject = {Toxikologie}, language = {en} } @article{ShephardLutzSchlatter1994, author = {Shephard, S. E. and Lutz, Werner K. and Schlatter, C.}, title = {The lacI transgenic mouse mutagenicity assay: quantitative evaluation in comparison to tests for carcinogenicity and cytogenetic damage in vivo}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60638}, year = {1994}, abstract = {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.}, subject = {Toxikologie}, language = {en} } @article{KlotzJesaitis1994, author = {Klotz, Karl-Norbert and Jesaitis, A. J.}, title = {The interaction of N-formyl peptide chemoattractant receptors with the membrane skeleton is energy-dependent}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60499}, year = {1994}, abstract = {Desensitization of N-fonnyl peptide chemoattractant receptors (FPR) in human neutrophils is thought to be achieved by lateral segregation of receptors and G proteins within the plane of the plasma membrane resulting in an interruption of the signalling cascade. Direct coupling of FPR to membrane skeletal actin appears to be the basis of this process~ however, the molecular mechanism is unknown. In this study we investigated the effect of energy depletion on formation of FPR-membrane skeleton complexes. In addition the effect of the protein kinase C inhibitor stauroporine and the phosphatase inhibitor okadaic acid on coupling of FPR to the membrane skeletonwas studied. Human neutrophils were desensitized using the photoreactive agonist N-formy1-met-leu-phe-1ys-N'[\(^{125}\)I]2(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (fMLFK-[\(^{125}\)I]ASD) after ATP depletion with NaF or after incubation with the respective inhibitors. The interaction of FPR with the membrane skeleton was studied by Sedimentation of the membrane skeleton-associated receptors in sucrose density gradients. Energy depletion of the cells markedly inhibited the formation of FPR-membrane skeleton complexes. This does not appear tobe related to inhibition of protein phosphorylation due to ATP depletion because inhibition of protein kinases and phosphatases bad no significant effect on coupling of FPR to the membrane skeleton. We conclude, therefore, that coupling of FPR to the membrane skeleton is an energy,dependent process which does not appear to require modification of the receptor protein by phosphorylation.}, subject = {Toxikologie}, language = {en} } @article{KlotzLohse1986, author = {Klotz, Karl-Norbert and Lohse, M. J.}, title = {The glycoprotein nature of A\(_1\) adenosine receptors}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60231}, year = {1986}, abstract = {A\(_1\) adenosine receptors from different tissues and species we~e photoaffinity labelled and then the carbohydrate content was examined by both enzymatic and chemical treatment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the labelled membrane receptors shows that neuraminidase treatment alters the electrophoretic mobility of the receptor band indica ting the presence of terminal neurandnie acids. Neuraminidase digestion does not influence the binding characteristics of the receptor. The totally deglycosylated receptor protein obtained by chemical treatment has an apparent molecular weight Of 32,000.}, subject = {Toxikologie}, language = {en} } @misc{SchlatterLutz1990, author = {Schlatter, J. and Lutz, Werner K.}, title = {The carcinogenic potential of ethyl carbamate (urethane): risk assessment at human dietary exposure levels}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60826}, year = {1990}, abstract = {Ethyl carbamate is found in fermented foods: bread contains 3-15 ng/g, stone-fruit brandies 200-20,000 ngfg, and about one-third of table-wine samples analysed contained more than 10 ng/g. In animals, ethyl carbamate is degraded to C02, H20 and NH3, with intermediate formation ofethanol. This degradation has been shown tobe inhibited (postponed) in the mouse by ethanol concentrations in the blood of about 0.15\% and higher. A quantitatively minor pathway involves a two-step oxidation of the ethyl group to vinyl carbamate and epoxyethyl carbamate, the postulated electrophilic moiety that reacts with DNA. This reaction is probably the mode of the mutagenic action observed in many cellular and animal systems. The fact that only vinyl carbamate, but not ethyl carbamate, is mutagenic in a standard Ames test is probably because there is insufficient production of the intermediate oxidation product in the standard test. Consistent with this metabolism is the carcinogenic activity of ethyl carbamate in various animal species and in different organs; this activity can be seen even after a single high dose in early life. Quantitative analysis of the total tumour incidences after chronic exposure of rats and mice to 0.1-12.5 mg ethyl carbamate/kg body weightjday in the drinking-water showed a dose-related increase. The main target organs were the mammary gland (female rats and mice having similar susceptibilities) and the Jung (mice only). On the basis of sex- and organ-specific tumour data and with a linear extrapolation to a negligible increase of the lifetime tumour incidence by 0.0001\% ( one additional tumour in one mil{\"u}on individuals exposed for life), a "virtually safe dose .. of 20 to 80 ng/kg body weight/day was estimated. The daily burden reached under normal dietary habits without alcoholic beverages is in the range of about 20 ng/kg body weightfday. Regular table-wine consumption would increase the risk by a factor of up to five. Regular drinking of 20 to 40 ml stone-fruit brandy per day could raise the calculated lifetime tumour risk to near 0.01\%.}, subject = {Toxikologie}, language = {en} } @article{DaenikenFriederichLutzetal.1981, author = {D{\"a}niken, A. von and Friederich, U. and Lutz, Werner K. and Schlatter, C.}, title = {Tests for mutagenicity in Salmonella and covalent binding to DNA and protein in the rat of the riot control agent o-chlorobenzylidene malononitrile (CS)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61073}, year = {1981}, abstract = {The aim of this study was to determine whether o-chlorobenzylidene malononitrile ( CS) exhibits any genotoxic activity towards Salmonella or mammalian DNA in vivo. CS was synthesized with a [\(^{14}\)C]-label at the benzylic carbon atom. It was administered i. p. at a dose level of 13 mg/kg (1 mCi/kg) to young adult male rats. Liverand kidney DNA was isolated after 8, 25, and 75 h. The radioactivity was at (liver, 8 and 75 h) or below (all other samples) the limit of detection of 3 dpm. Therefore, a possible binding of CS to DNA is at least 10\(^5\) times lower than that of the strong hepatocarcinogen aflatoxin B1, and 4,000 times lower than that of vinyl chloride. In contrast to this lack of DNA binding, but in agreement with the chemical reactivity of CS, a binding to nuclear proteins could be detected with specific activities ranging between 50 and 121 dpm/mg for liver and between 3 and 41 dpm/mg for kidney. Protein binding could well be responsible for its pronounced cytotoxic effects. Cs was also tested in the Ames Salmonella/microsome assay. Strains TA 1535, TA 1537, TA 1538, TA 98, and TA 100 were used with or without pre-incubation. Only with strain TA 100 and only without pre-incubation, a doubling of the number of revertants was detectable at the highest dose Ievels used, 1,000 and 2,000 !lg CS per plate. With pre-incubation of TA 100 with CS, a slight increase of the number of revertants was seen at 100 and 500 !lg per plate, and a subsequent fall below control values at 1,000 J.tg. A check for the number of surviving bacteria revealed a strong bacteriotoxicity of the higher doses of es so that the calculated mutation frequencies, i.e., the oumber of revertants per number of surviving bacteria, increased with doses up to 500 !J.g. This toxicity could be counteracted in part by the addition of increasing amounts of rat liver microsomes. In the view of these results, and taking into account the rare and low exposure of man, it is concluded that CS will not create a risk for the induction of point mutations or of carcinogenic processes mediated by DNA binding.}, subject = {Toxikologie}, language = {en} } @article{HintzscheJastrowKleineOstmannetal.2012, author = {Hintzsche, Henning and Jastrow, Christian and Kleine-Ostmann, Thomas and K{\"a}rst, Uwe and Schrader, Thorsten and Stopper, Helga}, title = {Terahertz electromagnetic fields (0.106 THz) do not induce manifest genomic damage in vitro}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76268}, year = {2012}, abstract = {Terahertz electromagnetic fields are non-ionizing electromagnetic fields in the frequency range from 0.1 to 10 THz. Potential applications of these electromagnetic fields include the whole body scanners, which currently apply millimeter waves just below the terahertz range, but future scanners will use higher frequencies in the terahertz range. These and other applications will bring along human exposure to these fields. Up to now, only a limited number of investigations on biological effects of terahertz electromagnetic fields have been performed. Therefore, research is strongly needed to enable reliable risk assessment. Cells were exposed for 2 h, 8 h, and 24 h with different power intensities ranging from 0.04 mW/cm2 to 2 mW/cm2, representing levels below, at, and above current safety limits. Genomic damage on the chromosomal level was measured as micronucleus formation. DNA strand breaks and alkali-labile sites were quantified with the comet assay. No DNA strand breaks or alkali-labile sites were observed as a consequence of exposure to terahertz electromagnetic fields in the comet assay. The fields did not cause chromosomal damage in the form of micronucleus induction.}, subject = {Toxikologie}, language = {en} } @article{LohseMaurerKlotzetal.1989, author = {Lohse, M. J. and Maurer, K. and Klotz, Karl-Norbert and Schwabe, U.}, title = {Synergistic effects of calcium-mobilizing agents and adenosine on histamine release from rat peritoneal mast cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60346}, year = {1989}, abstract = {1 Adenosine and its metabolically stable analogue N.etbyl-carboxamidoadenosine (NECA) enhance histamine release from rat peritoneal mast cells when tbese are stimulated by calciummobilizing agents. NECA and adenosine shift the concentration-response curve of tbe calcium ionophore A23187 to lower concentrations. 2 The potencies of NECA or adenosinein enhancing A23187-induced histamine release are dependent on the Ievel of stimulated release in tbe absence of adenosine analogues. At high Ievels of release their potencies are up to 20 times higher than at low Ievels. Consequently, averaged concentration-response curves of adenosine and NECA for enhancing bistamine release are shallow. 3 The adenosine transport blocker S-(p-nitrobenzyl)-6-thioinosine (NBTI) has no effect by itself at low Ievels of stimulated histamine release, but abolishes the enhancing effect of adenosine. At high Ievels of release, however, NBTI alone enhances the release of histamine. 4 lt is concluded that adenosine and calcium reciprocally enhance the sensitivity of the secretory processes to the effects of the other agent. The Ievels of intracellular adenosine obtained by trapping adenosine inside stimulated mast cells are sufficient to enhance histamine release substantially, suggesting that this effect may play a physiological and pathophysiological role.}, subject = {Toxikologie}, language = {en} } @inproceedings{Lutz1984, author = {Lutz, Werner K.}, title = {Structural characteristics of compounds that can be activated to chemically reactive metabolites: use for a prediction of a carcinogenic potential}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-80105}, year = {1984}, abstract = {Many mutagens and carcinogens act via covalent interaction of metabolic intermediates with DNA in the target cell. This report groups those structural elements which are often found to form the basis for a metabolism to such chemically reactive metabolites. ~mpounds which are chemically reactive per se and which do not require metabolic activation form group 1. Group 2 compri~es of olefins and aromatic hydrocarbons where the oxidation via an epoxide can be responsible for the generation of reactive species. Aromatic amines, hydrazines, and nitrosamirres form group 3 requiring an oxidation of a nitrogen atom or of a carbon atom in alpha position to a nitrosated amine. Group 4 compounds are halogenated hydrocarbons which can either give rise to radicals or can form an ·olefin (group 2) upon dehydrohalogenation. Group 5 compounds depend upon some preceding enzymatic activity either not available in the target cell or acting on positions in the molecule which are not directly involved in the subsequent formation of electrophilic atoms. Examples for each group are taken from the "List of Chemieals and Irrdustrial Processes Associated with Cancer in Humans" as compiled by the International Agency for the Research on Cancer, and it is shown that 91\% of the organic carcinogens would have been detected on the basis of structural elements characteristic for group 1-5. As opposed to this very high sensitivity, the specificity ( the true negative fraction) of using this approach as a short-term test for carcinogenicity is shown to be bad because detoxification pathways have so far not been taken into account. These competing processes are so complex, however, that either only very extensive knowledge about pharmacokinetics, stability, and reactivity will be required or that in vivo systems have to be used to predict, on a quantitative basis, the darnage expected on the DNA. DNA-binding experiments in vivo are presented with benzene and toluene to demonstrate one possible way for an experimental assessment and it is shown that the detoxification reaction at the methyl group available only in toluene gives rise to a reduction by at least a factor of forty for the binding to rat liver DNA. This quantitative approach available with DNA-binding tests in vivo, also allows evaluation as to whether reactive metabolites and their DNA binding are always the most important single activities contributing to the overall carcinogenicity of a chemical. With the example of the livertumor inducing hexachlorocyclohexane isomers it is shown that situations will be found where reactive metabolites are formed and DNA binding in vivo is measurable but where this activity cannot be the decisive mode of carcinogenic action. It is concluded that the lack of structural elements known to become potentially reactive does not guarantee the lack of a carcinogenic potential.}, subject = {Toxikologie}, language = {en} } @article{BuesserLutz1987, author = {B{\"u}sser, M. T. and Lutz, Werner K.}, title = {Stimulation of DNA synthesis in rat and mouse liver by various tumor promoters}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60908}, year = {1987}, abstract = {In order to investigate whether the Stimulation of liver DNA synthesis might be used to detect one class of hepatic tumor promoters, the incorporation of orally administered radiolabelled thymidine into liver DNA was detennined in rats and mice 24 h after a single oral gavage of test compounds at various dose Ievels. Three DNA-binding hepatocarcinogens, aflatoxin B1; benzidine and carbon tetrachloride, did not stimulate but rather inhibited DNA synthesis (not for CCla). Four hepatic tumor promoters, clofibrate, DDT, phenobarbital and thioacetamide, gave rise to a Stimulation in a dosedependent manner. Single oral doses between 0.02 and 0.3 mmol/kg were required to double the level of thymidine incorporation into liver DNA (= doubling dose, DD). Differentes between species or sex as obsprved in long-term carcinogenicity studies were reflected by a different stimulation of liver DNA synthesis. In agreement with the bioassay data, aldrin was positive only in male mice (DD = 0.007 mmol/kg) but not in male rats or female mice. 2,3, 7,8-TCDD was positive in male mice (DD = 10\(^{-6}\) mmol/kg) andin female rats (DD = 2 x 10\(^{-6}\) mmol/kg) but not in male rats. The assay was also able to distinguish between structural isomers with different carcinogenicities. [alpha]Hexachlorocyclohexane stimulated Iiver DNA synthesis with a doubling dose of about 0.2 mmol/kg in male rats whereas the [gamma]isomer was ineffective even at l mmol/kg. So far, only one result was inconsistent with carcinogenicity bioassay data. The different carcinogenicity of di(2-ethylhexyl)adipate (negative in rats) and di(2-ethylhe.xyl)phthalate (positive) was not detectable. 8oth plasticizers were positive in.this short-term system with DD's of 0. 7 mmol/kg for DEHA and 0.5 mmol/kg for DEHP. The proposed assay is discussed as an attempt to devise short-term assays for carcinogens not detected by the routine genotoxicity test systems.}, subject = {Toxikologie}, language = {en} } @article{GimplGerstbergerMaussetal.1990, author = {Gimpl, G. and Gerstberger, R. and Mauss, U. and Klotz, Karl-Norbert and Lang, R. E.}, title = {Solubilization and characterization of active neuropeptide-Y receptors from rabbit kidney}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60375}, year = {1990}, abstract = {Active neuropeptide Y receptors were solubilized from rabbit kidney membranes using the zwitterionic detergent 3-[ (3-cholamidopropy l)dimethylammonio ]- 1-propanesulfonic acid (CHAPS). In membrane fragmentsandsoluble extracts neuropeptide Y bindingwas time dependent, saturable, reversible, and of high affinity. Scatchard analysis of equilibrium binding data indicated a single class of binding sites with respective Kn and Bmax values of 0.09 nM and 530 fmol/mg of protein for the membrane-bound receptors and 0.10 nM and 1585 fmol/mg of protein for the soluble receptors. Neuropeptide Y bindingwas specifically inhibited by the nonhydrolyzable GTP analog guanosine 5' -0- (3-thiotripbosphate) in a concentration-dependent manner, with IC\(_{50}\) values of 28 and 0.14 \(\mu\)M for membrane- bound and soluble receptors, respectively, suggesting that neuropeptide Y receptors are functionally coupled to GTP-binding regulatory proteins. CrossHoking studies were performed with the heterobifunctional N-hydroxysuccinimidyl-4-azidobenzoate and the monofunctional neuropeptide Y derivative, azidobenzoyl and led to the identification of a 100 kDa peptide that should represent the covalently labeled neuropeptide Y receptor.}, subject = {Toxikologie}, language = {en} } @article{FischerLutz1994, author = {Fischer, W. H. and Lutz, Werner K.}, title = {Short communication : Mouse skin papilloma formation by chronic dermal application of 7,12-dimethylbenz[a]anthracene is not reduced by diet restriction}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60644}, year = {1994}, abstract = {No abstract available}, subject = {Toxikologie}, language = {en} } @article{LohseElgerLindenbornFotinosetal.1988, author = {Lohse, M. J. and Elger, B. and Lindenborn-Fotinos, J. and Klotz, Karl-Norbert and Schwabe, U.}, title = {Separation of solubilized A\(_2\) adenosine receptors of human platelets from non-receptor [\(^3\)H]NECA binding sites by gel filtration}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60309}, year = {1988}, abstract = {Human platelet membranes were solubilized with the zwitterionic detergent CHAPS (3-[3-(cholamidopropyl)dimethylammonio]- 1-propanesulfonate) and the solubilized extract subjected to gel ftltration. Binding of the adenosine receptor agonist [\(^3\)H]NECA (5'-N-ethylcarboxamidoadenosine) was measured to the eluted fractions. Two [\(^3\)H]NECA binding peaks were eluted, the first of them with the void volume. This first peak represented between 10\% and 25\% of the [\(^3\)H]NECA binding activity eluted from the column. It bound [\(^3\)H]NECA in a reversible, saturable and GTPdependent manner with an affinity of 46 nmol/1 and a binding capacity of 510 fmol/mg protein. Various adenosine receptor ligands competed for the binding of [\(^3\)H]NECA to the frrst peak with a pharmacological proftle characteristic for the A\(_2\) adenosine receptor as determined from adenylate cyclase experiments. In contrast, most adenosine receptor ligands did not compete for [\(^3\)H]NECA binding to the second, major peak. These results suggest that a solubilized A\(_2\) receptor-Gs protein complex of human platelets can be separated from other [\(^3\)H]NECA binding sites by gel filtration. This allows reliable radioligand binding studies of the A2 adenosine receptor of human plate1ets.}, subject = {Toxikologie}, language = {en} } @inproceedings{SagelsdorffLutz1987, author = {Sagelsdorff, P. and Lutz, Werner K.}, title = {Sensitivity of DNA and nucleotides to oxidation by permanganate and hydrogen peroxide}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-80062}, year = {1987}, abstract = {no abstract available}, subject = {Toxikologie}, language = {en} } @article{LutzSchlatter1977, author = {Lutz, Werner K. and Schlatter, C.}, title = {Saccharin does not bind to DNA of liver or bladder in the rat [Short Communication]}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61194}, year = {1977}, abstract = {No abstract available}, subject = {Toxikologie}, language = {en} }