@article{LutzSchlatter1978, author = {Lutz, Werner K. and Schlatter, C.}, title = {A closed inhalation system for pharmacokinetic and metabolism studies of volatile compounds with small laboratory animals}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-80145}, year = {1978}, abstract = {In the inhalation system described an animal can be kept in the same atmosphere of a 2-liter desiccator for up to 24 h. The expired carbon dioxide is adsorbed with soda lime and the resulting reduced pressure is balanced by a supply of oxygen also used for the inflow of the chemical to be investigated. Urine and faeces can be collected ~eparately and the system allows a periodical control of the concentration of the chemical by sampling the air with needle and syringe.}, subject = {Toxikologie}, language = {en} } @article{ShephardSchlatterLutz1987, author = {Shephard, S. E. and Schlatter, C. and Lutz, Werner K.}, title = {Assessment of the risk of formation of carcinogenic N-nitroso compounds from dietary precursors in the stomach}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60925}, year = {1987}, abstract = {A literature review has shown that the daily intakes of various N -nitroso-precursor classes in a typical European diet span five orders of magnitude. Amides in the form of protein, and guanidines in the form of creatine and creatinine, are the nitrosatable groups found most abundantly in the diet, approaching Ievels of 100 g/day and 1 gjday, respectively. Approximately 100 mg of primary amines and amino acids are consumed daily, whereas aryl amines, secondary amines and ureas appear to lie in the 1-10 mg range. The ease of nitrosation of each precursor was estimated, the reactivities being found to span seven orders of magnitude, with ureas at the top and amines at the bottom of the scale. From this infonnation and an assessment of the carcinogenicity of the resulting N-nitroso derivatives, the potential health risk due to gastric in vivo nitrosation was calculated. The combined effects of these risk variables were analysed using a simple mathematical model: Risk = [daily intake of precursor] x [gastric concentration of nitrite]\(^n\) x [nitrosatability rate constant} x [carcinogenicity of derivative]. The risk estimates for the various dietary components spanned nine orders of magnitude. Dietary ureas and aromatic amines combined with a high nitrite burden could pose as great a risk as the intake of preformed dimethylnitrosamine in the diet. In contrast, the risk posed by the in vivo nitrosation of primary and secondary amines is probably negligib1y small. The risk contribution by amides (including protein), guanidines and primary amino acids is intermediate between these two extremes. Thus three priorities for future work are a comprehensive study of the sources and Ievels of arylamines and ureas in the diet, determination of the carcinogenic potencies of key nitrosated products to replace the necessarily vague categories used so far, and the development of short-term in situ tests for studying the alkylating power or genotoxicity of N-nitroso compounds too unstable for inclusion in long-term studies.}, subject = {Toxikologie}, language = {en} } @article{JaggiLutzSchlatter1979, author = {Jaggi, W. and Lutz, Werner K. and Schlatter, C.}, title = {Comparative studies on the covalent binding of the carcinogen benzo(a)pyrene to DNA in various model systems}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61131}, year = {1979}, abstract = {The covalent binding of tritiated benzo(a)pyrene (BP) to DNA has been determined in rat liver in vivo, in rat liver perfused in situ, after incubation of BP with liver single cells, with liver homogenate, with liver microsomes and DNA, with fibroblasts from a rat granulorna pouch, and with · 2 cell lines. Li ver single cells were found to be a valuable compromise between the rnost sensitive system (microsomal incubation of BP with DNA) and the biologically most relevant system (in vivo ).}, subject = {Toxikologie}, language = {en} } @article{LutzJaggiSchlatter1982, author = {Lutz, Werner K. and Jaggi, W. and Schlatter, C.}, title = {Covalent binding of diethylstilbestrol to DNA in rat and hamster liver and kidney [Short Communication]}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61066}, year = {1982}, abstract = {No abstract available}, subject = {Toxikologie}, language = {en} } @article{JaggiLutzSchlatter1978, author = {Jaggi, W. and Lutz, Werner K. and Schlatter, C.}, title = {Covalent binding of ethinylestradiol and estrone to rat liver DNA in vivo}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61162}, year = {1978}, abstract = {Thecovalent bindingof [6,7-\(^3\)H]ethinylestradiol (EE)and [6,7-\(^3\)H]estrone (E) to liver DNA of 200 g female ratswas measured 8 h after the administration of 80 \(\mu\)g (9.2 mCi) estrogen by gavage. The binding is 1.5 for EE and 1.1 for E, expressedas binding to DNA/dose, in units of \(\mu\)mol hormonefmol DNA phosphate/mmole honnone/kg body wt. It is in the same order of magnitude as for benzene and about 10 000 tim es below the binding of typical liver carcinogens, such as aflatoxin B\(_1\) or N,N-dimethylnitrosamine.}, subject = {Toxikologie}, language = {en} } @article{SagelsdorffLutzSchlatter1988, author = {Sagelsdorff, P. and Lutz, Werner K. and Schlatter, C.}, title = {DNA methylation in rat liver by daminozide, 1,1-dimethylhydrazine, and dimethylnitrosamine}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60875}, year = {1988}, abstract = {DNA Methylation in Rat Li ver by Daminozide, 1, 1-Dimethylhydrazine, and Dimethylnitrosamine. SAGELSDORFF, P., LUTZ, W. K., AND ScHLAITER C. (1988). Fundam. Appl. Toxico/. 11, 723-730. [methyP4C]Daminozide (succinic acid 2',2'-dimethylhydrazide; 37 mgjkg), l,l( 14C]dimethylhydrazine (UDMH; 19 mgtkg), and (14C]dimethylnitrosamine (DMNA; 0.1 mg/ kg) were administered by oral gavage to male Sprague-Dawley rats. After 24 hr, the animals were killed and DNA was purified from the livers to constant specific radioactivity. After enzymatic degradation of the DNA to the 3'-deoxynucleotides the Ievel of DNA methylation was determined by HPLC analysis. Radiolabeled 7-methylguanine (7mG) was identified by cochromatography with unlabeled 7mG added as standard after acidic depurination of DNA and HPLC analysis ofpurines and apurinic acid. All three compounds were found to methylate DNA. The relative potencies were 1:47:4900 for daminozide:UDMH:DMNA. With [methyPH]UDMH, the formation of7mG was investigated as a function of dose administered, at 20, 2, and 0.2 mgj kg. The methylation ofDNA was strictly proportional to the dose. The data were used to compare the Ievel of DNA alkylation derived from residues of daminozide and UDMH in treated apple with the genotoxicity of the intake of N-nitroso compounds in Germany and Japan. It is estimated that these residues could Iead to a DNA methylation in the Ii ver of about 6\% of an average exposure to DMNA}, subject = {Toxikologie}, language = {en} } @article{OhgakiLudekeMeieretal.1991, author = {Ohgaki, H. and Ludeke, B. I. and Meier, I. and Kleihues, P. and Lutz, Werner K. and Schlatter, C.}, title = {DNA methylation in the digestive tract of F344 rats during chronic exposure to N-methyl-N-nitrosourea}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60759}, year = {1991}, abstract = {The formation of \(O^6\)-methyldeoxyguanosine (\(O^6\)-MedGuo) was determined by an immuno-slot-blot assay in DNA of various tissues of F344 rats exposed to N-methyl-N-nitrosourea (MNU) in the drinking waterat 400 ppm for 2 weeks. Although the pyloric region of the glandular stomach is a target organ under these experimental conditions, the extent of DNA methylation was highest in the forestomach (185 \(\mu\)mol \(O^6\)-MedGuojmol guanine). Fundus (91 J.!moljmol guanine) and pylorus (105 J.!moljmol guanine) of the glandular stomach, oesophagus (124 \(\mu\)mol/mol guanine) and duodenum (109 )lmoljmol guanine) showed lower Ievels of \(O^6\) - MedGuo but differed little between each other. Thus, no correlation was observed between target organ specificity and the extent of DNA methylation. This is in contrast to the gastric carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), which preferentially alkylates DNA of the pylorus, the main site of induction of gastric carcinomas by this chemical. In contrast to MNU, the nonenzymic decomposition of MNNG is accelerated by thiol compounds (reduced glutathione, L-cysteine), which are present at much higher concentrations in the glandular stomach than in the forestomach and oesophagus. During chronic exposure to MNNG (80 ppm), mucosal cells immunoreactive to 0 6-MedGuo are limited to the luminal surface [Kobori et al. (1988) Carcinogenesis 9:2271-2274]. Although MNU (400 ppm) produced similar Ievels of \(O^6\)-MedGuo in the pylorus, no cells containing methylpurines were detectable by immunohistochemistry, suggesting a more uniform methylation of mucosal cells by MNU than by MNNG. After a single oral dose of MNU (90 mg/kg) cells containing methylpurines were unequivocally identified using antibodies to \(O^6\)-MedGuo and the imidazole-ring-opened product of 7-methyldeoxyguanosine. In the gastric fundus, their distribution was similar to those methylated by exposure to MNNG, whereas the pyloric region contained immunoreactive cells also in the deeper mucosallayers. After a 2-week MNU treatment, the rate of cell proliferation, as determined by bromodeoxyuridine immunoreactivity, was only slightly enhanced in the oesophagus andin the fundus, but markedly in the forestomach and the pyloric region of the glandular stomach. lt is concluded that the overall extent of DNA methylation, the distribution of alkylated cells within the mucosa and the proliferative response all contribute to the organ-specific carcinogenicity of MNU.}, subject = {Toxikologie}, language = {en} } @article{BaertschLutzSchlatter1991, author = {Baertsch, A. and Lutz, Werner K. and Schlatter, C.}, title = {Effect of inhalation exposure regimen on DNA binding potency of 1,2-dichloroethane in the rat}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60743}, year = {1991}, abstract = {1 ,2-Dichloroethane (DCE) was reported to be carcinogenic in rats in a long-tenn bioassay using gavage in com oil (24 and 48 mg/kg/day), but not by inhalation (up to 150-250 ppm, 7 h/day, 5 days/week). The daily dose metabolized was similar in the two experiments. In order to address this discrepancy, the genotoxicity of DCE was investigated in vivo under different exposure conditions. Fernale F-344 rats (183-188 g) were exposed to [1,2-14C]DCE in a closed inhalation chamber to either a low, constant concentration (0.3 mg/l = 80 ppm for 4 h) or to a peak concentration (up to 18 mg/1 = 4400 ppm) for a few minutes. After 12 h in the chamber, the dose metabolized under the two conditions was 34 mg/kg and 140 mg/k:g. DNA was isolated from liver and lung and was purified to constant specific radioactivity. DNA was enzymaticaBy hydrolyzed to the 3' -nucleotides which were separated by reverse phase HPLC. Most radioactivity eluted without detectable or with little optical density' indicating that the major part of the DNA radioactivity was due to covalent binding of the test compound. The Ievel of DNA adducts was expressed in the dose-nonnalized units ofthe Covalent Binding Index, CBI = f.Lmol adduct per mol DNA nucleotide/ mmol DCE per kg body wt. In liver DNA, the different exposure regimens resulted in markedly different CBI values of 1.8 and 69, for "constant-low" and ''peak" DCE exposure Ievels. In the Jung, the respective values were 0.9 and 31. It is concluded that the DNA darnage by DCE depends upon the concentration-time profile and that the carcinogenic potency determined in the gavage study should not be used for low-Ievel inhalation exposure.}, subject = {Toxikologie}, language = {en} } @article{VivianiDaenikenSchlatteretal.1980, author = {Viviani, A. and D{\"a}niken, A. von and Schlatter, C. and Lutz, Werner K.}, title = {Effect of selected induction of microsomal and nuclear aryl hydrocarbon monooxygenase and epoxide hydrolase as well as cytoplasmic glutathione S-epoxide transferase on the covalent binding of the carcinogen benzo(a)pyrene to rat liver DNA in vivo}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61114}, year = {1980}, abstract = {Groups of four adult male rats [ZUR:SIV -Z] were pretreated with corn oil (control; 2 ml/kg/day i. p. for 3 days), trans-stilbene-oxide (SO; 200 mg/kg/day i. p. for 2 days), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 \(\mu\)g/kg i. p. once, 4 days before killing), phenobarbital (PB; 1 gjliter in the drinking water for 8 days), and dieldrin (20 mg/kg/day i. p. for 3 or 9 days). They received an injection of [G-\(^3\)H]benzo(a)pyrene (BaP, 31 \(\mu\)g/kg, 7.4. 10\(^9\) dpm/kg; i. v.) 16 h before killing. In the liver of each rat, five enzymatic activities and the covalent binding of BaP to DNA have been determined. The rnicrosomal aryl hydrocarbon monooxygenase activity (AHM) ranged frorn 75\% of control (SO) to 356\% (TCDD), the nuclear AHM from 63\% (SO) to 333\% (TCDD). Microsomal epoxide hydrolase activity (EH) was induced up to 238\% (PB), nuclear EH ranged from 86\% (TCDD) to 218\% (PB). A different extent of induction was observed in the two compartments. Highest induction of glutathione S-epoxide transferase activity (GST) was found with PB (202\%). The DNA binding of BaP was modulated within 79\% (dieldrin, 9 days) and 238\% of control (TCDD). An enzyme digest of control DNA was analysed by Sephadex LH-20 chromatography. Multiple linear regression analysis with all data expressedas o/o of control yielded the following equation: DNA Binding = 1.49 · Microsomal AHM- 1.07 · Nuclear AHM+ 0.33 · Microsomal EH- 0.52 · N uclear EH+ 0.11 · Cytoplasmic GST + 58.2. From this analysis it is concluded that (1) AHM located in the endoplasmic reticulum is most important in the formation of DNA-binding metabolites, (2) EH in the same compar.tment is not determinative in thls respect nor has it a protective effect, (3) both membrane-bound enzyme activities located in the nucleus may inactivate potential ultimate carcinogens, and ( 4) cytoplasmic GST probably cannot reduce DNA binding due to its subcellular localization.}, subject = {Toxikologie}, language = {en} } @inproceedings{LutzSchlatter1978, author = {Lutz, Werner K. and Schlatter, C.}, title = {Extrapolation of carcinogenicity data to low doses with a dose-response study of the binding of benzo(a)pyrene to rat liver DNA}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-80157}, year = {1978}, abstract = {The binding of tritiated benzo(a)pyrene (BP) to liver DNA of 25 adult male rats (SIV 50) has been determined 50 h after a single intraperitoneal injection of doses between 40 ug/kg and 4; mg/kg. The dose-response relations~ ip is linear up to i mg/kg, shows a sigmoid step towards 2 mg/kg and a shallow linear. slope above that value. TlJe 0 bserved bin ding ranges from 1.7 to 180 nmoles BP per mole DNA phosphate. The non-linearity between 1 and 2 mg/kg could be explained 0):1 the basis of an induction of metabolizing enzymes. A pure1y mathematical extrapolation of therumour incidence from a carcinogenic dose (1 x 40mg/kg for a 20\% hepatoma incidence in newborn mice) to human exposure levels (aboilt 0.1 ug/kg per day) would never have followed a step like the on~ found in our experiments. Our dose-effect study therefore shows how carcinogenitity data could be extrapolated in a biologically founded way to low doses.}, subject = {Toxikologie}, language = {en} } @article{KuglerSteigmeierFriederichGrafetal.1989, author = {Kugler-Steigmeier, M. E. and Friederich, U. and Graf, U. and Lutz, Werner K. and Maier, P. and Schlatter, C.}, title = {Genotoxicity of aniline derivatives in various short-term tests}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60857}, year = {1989}, abstract = {Various substituted aniline derivatives were tested for genotoxicity in several short-term tests in order to examine the hypothesis that a Substitution at both ortho positions (2,6-disubstitution) could prevent genotoxicity due to steric hindrance of an enzymatic activation to electrophilic intermediates. In the Salmonellajmicrosome assay, 2,6-dialkylsubstituted anilines and 2,4,6-trimethylaniline (2,4,6-TMA) were weakly mutagenic in strain TA100 when 20\% S9 mixwas used, although effects were small compared to those of 2,4-dimethylaniline and 2,4,5-trimethylaniline (2,4,5-TMA). In Drosophila me/anogaster, however, 2,4,6-TMA and 2,4,6-trichloroaniline (TCA) were mutagenic in the wing spottestat 2-3 times lower doses than 2,4,5-TMA. In the 6-thioguanine resistance test in cultured fibroblasts, 2,4,6-TMA was again mutagenic at lower doses than 2,4,5-TMA. Two methylene-bis-aniline derivatives were also tested with the above methods: 4,4'-methylene-bis-(2-chloroaniline) (MOCA) was moderately genotoxic in al1 3 test systems whereas 4,4'-methylene-bis-(2-ethyl-6-methylaniline) (MMEA) showed no genotoxicity at all. DNA binding sturlies in rats, however, revealed that both MOCA and MMEA produced DNA adducts in the liver at Ievels typically found for moderately strong genotoxic carcinogens. These results indicate that the predictive value of the in vitro test systems and particularly the Salmonellajmicrosome assay is inadequate to detect genotoxicity in aromatic amines. Genotoxicity seems to be a general property of aniline derivatives and does not seem to be greatly influenced by substitution at both ortho positions.}, subject = {Toxikologie}, language = {en} } @article{LutzJaggiLuethyetal.1980, author = {Lutz, Werner K. and Jaggi, W. and L{\"u}thy, J. and Sagelsdorff, P. and Schlatter, C.}, title = {In vivo covalent binding of aflatoxin B\(_1\) and aflatoxin M\(_1\) to liver DNA of rat, mouse and pig}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61097}, year = {1980}, abstract = {[\(^{14}\)C] Aflatoxin B\(_1\) (AFB\(_1\)) was isolated from cultures of Aspergillus parasiticus grown on [1-\(^{114}\)C] sodium acetate. Covalent binding of AFB1 to liver DNA of rat and mouse was determined 6-8 h afteroral administration. The effectiveness of covalent binding, expressedas DNA binding per dose in the units of a 'Covalent Binding Index' (CBI), (\(\mu\)mol aflatoxin/mol DNA nucleotides)/(mmol aflatoxin/kg animal), was found to be 10 400 for rats and 240 for mice. These CBI partly explain the different susceptibility of the two species for the incidence of hepatic tumors. The corresponding values for pig liver DN A, 24 and 48 h after oral administration, were found to be as high as 19 100 and 13 300. DNA-binding has not so far been reported for this species although it could represent an appropriate animal model for studies where a human-like gastrointestinal tract physiology is desirable. Aflatoxin M \(_1\) ( AFM\(_1\)) is a metabolite found in the milk of cows that have been fed AFB\(_1\)-contaminated diet. [\(^{14}\)C] AFM\(_1\) was also found to be produced by cultures of A. parasiticus giving a yield of about 0.3\% of the total aflatoxins. A test for covalent binding to rat liver DN A revealed a CBI of 2100 shoWing that AFM\(_1\) must also be regarded as a strong hepatocarcinogen. It is concluded that AFB\(_1\) contaminations should be avoided in dairy feed.}, subject = {Toxikologie}, language = {en} } @article{JaggiLutzLuethyetal.1980, author = {Jaggi, W. and Lutz, Werner K. and L{\"u}thy, J. and Zweifel, U. and Schlatter, C.}, title = {In vivo covalent binding of aflatoxin metabolites isolated from animal tissue to rat-liver DNA}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61101}, year = {1980}, abstract = {Ring-labelled [\(^{14}\)C)aflatoxin B\(_1\) (AFB\(_1\)), prepared by biosynthesis. or generally labelled [\(^3\)H]AFB\(_1\) was administered by oral gavage to young adult male rats. After 6 hr. the liver was removed and two fractions were isolated, namely macromolecules, which contamed about 3 \% of the initial dose of AFB\(_1\) radioactivity. and water-soluble, low-molecular aftatoxin conjugates containing about0·2\% of the administered radioactivity. These two fractions were administered orally to other rats in order to determine the potential of radioactive aftatoxin residues for covalent binding to DNA. Such binding can be used as an indicator for carcinogenic potency. Liver DNA was isolated 9-12 hr after admmistration of the aflatoxin derivatives and in no case was any radioactivity detected on the DNA. It can be deduced on the basis of the limit of detection of radioactivity on the DNA, that macromolecule bound AFB\(_1\) derivatives are at least 4000 times less active than AFB\(_1\) with respect to covalent binding to rat-liver DNA. and that the water-soluble conjugates are at least 100 times less potent than AFB, itself. It is concluded that the carcinogenic risk for humans who consume liver or meat. containing such aflatoxin residues is negligible when compared with the risk from intake of aftatoxins in other food items.}, subject = {Toxikologie}, language = {en} } @article{CaviezelLutzMininietal.1984, author = {Caviezel, M. and Lutz, Werner K. and Minini, U. and Schlatter, C.}, title = {Interaction of estrone and estradiol with DNA and protein of liver and kidney in rat and hamster in vivo and in vitro}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60995}, year = {1984}, abstract = {(6,7-\(^3\)H] Estrone (E) and [6,7-\(^3\)H]estradiol-17ß (E\(_2\)) have been synthesized by reduction of 6-dehydroestrone and 6-dehydroestradiol with tritium gas. Tritiated E and E\(_2\) were administered by oral gavage to female rats and to male and female hamsters on a dose level of about 300 \(\mu\)g/kg (54 mCi/kg). After 8 h, the liver was excised from the rats; liver and kidneys were taken from the hamsters. DNA was purified either directly from an organ homogenate or via chromatin. The radioactivity in the DNA was expressed in the units of the Covalent Binding Index, CBI = (\(\mu\)mol chemical bound per mol Similar considerations can be made for the liver where any true covalent DNA binding must be below a Ievel of 0.01. It is concluded that an observable tumor induction by estrone or estradiol is unlikely to be due to DNA binding. DNA-P)/(mmol chemical administered per kg b.w.). Rat liver DNA isolated via chromatin exhibited the very low values of 0.08 and 0.09 for E and E\(_2\) respectively. The respective figures in hamster liver were 0.08 and 0.11 in females and 0.21 and 0.18 in the males. DNA isolated from the kidney revealed a detectable radioactivity only in the female, with values of 0.03 and 0.05 for E and E\(_2\) respectively. The values for male hamster kidney were < 0.01 for both hormones. The minute radioactivity detectable in the DNA samples does not represent covalent binding to DNA, however, as indicated by' two sets of control experiments. (A) Analysis by HPLC of the nucleosides prepared by enzyme digest of liver DNA isolated directly or via chromatin did not reveal any consistent peak which could have been attributed to a nucleoside-steroid adduct. (B) All DNA radioactivity could be due to protein contaminations, because the specific activity of chromatin protein was determined to be more than 3 ,000 tim es high er than of DNA. The high affinity of the hormone to protein was also demonstrated by in vitro incubations, where it could be shown that the specific activity of DNA and protein was essentially proportional to the concentration of radiolabelled hormone in the organ homogenate, regardless of whether the animal was treated or whether the hormone was added in vitro to the homogenate. Carcinogens acting by covalent DNA binding can be classified according to potency on the basis of the Covalent Binding Index. Values of 10\(^3\)-10\(^4\) have been found for potent, 10\(^2\) for moderate, and 1-10 for weak carcinogens. Since estrone is moderately carcinogenic for the kidney of the male hamster, a CBI of about 100 would be expected. The actually measured Iimit of detection of 0.01 places covalent DNA binding among the highly unlikely mechanisms of action.}, subject = {Toxikologie}, language = {en} } @article{DaenikenLutzJaeckhetal.1984, author = {D{\"a}niken, A. von and Lutz, Werner K. and J{\"a}ckh, R. and Schlatter, C.}, title = {Investigation of the potential for binding of Di(2-ethylhexyl) phthalate (DEHP) and Di(2-ethylhexyl) adipate (DEHA) to liver DNA in vivo}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61004}, year = {1984}, abstract = {Investigation of the Potential for Binding of Di(2-ethylhexyl) Phthalate (DEHP) and Di(2- ethylhexyl) Adipate (DEHA) to Liver DNA in Vivo. VON D{\"A}NIKEN, A., LUTZ, W. K., J{\"A}CKH, R., AND ScHLATTER, C. (1984). Toxico/. App/. Pharmaco/. 73, 373-387. It was the aim oftbis investigation to determine whether covalent binding of di(2-ethylhexyl) phthalate (DEHP) to rat liver DNA and of di(2-ethylhexyl) adipate (DEHA) to mouse liver DNA could be a mechanism of action contributing to the observed induction of liver tumors after lifetime feeding of the respective rodent species with high doses of DEHP and DEHA. For this purpose, DEHP and DEHA radiolabeled in different parts of the molecule were administered orally to female rats and mice, respectively, with or witbout pretreatment for 4 weeks with 1\% unlabeled compound in the diet. Liver DNA was isolated after 16 hr and analyzed for radioactivity. The data were converted to a covalent binding index, CBI = (micromoles of substance bound per mole of DNA nucleotides)/(millimoles of substance applied per kilogram body weight), in order to allow a quantitative comparison also with other carcinogens and noncarcinogens. Administration of [\(^{14}\)H]carboxylate-labeled DEHP to rats resulted in no measurable DNA radioactivity. The Iimit of detection, CBI < 0.02 was about 100 times below the CBI of compounds where an observable tumor-inducing potential could be due to genotoxicity. With [\(^{14}\)C]- and [\(^{3}\)H]DEHP labeled in the alcohol moiety, radioactivity was clearly measurable in rat liver DNA. HPLC analysis of enzyme-degraded or acid-hydrolyzed DNA revealed that the natural nucleosides or purine bases were radiolabeled whereas no radioactivity was detectable in those fractions where tbe carcinogenmodified nucleoside or base adducts are expected. The respective Iimits of detection were at 0.07 and 0.04 CBI units for the \(^{14}\)C and \(^{3}\)H Iabels, respectively. The experiments with [\(^{14}\)C]- and [\(^{3}\)H]DEHA, labeled in the alcobol moiety and administered to mice, revealed aminute radioactivity of <50 dpm/mg liver DNA, too little to allow a nucleoside analysis to determine that fraction of the radioactivity which bad been incorporated via biosynthesis. Expressed in the CBI units, values of 0.05 to 0.15 for \(^{14}\)C and 0.01 to 0.12 for \(^{3}\)H resulted. Determination of the level· of \(^{14}\)C02 expiration revealed a linear correlation with the speciftc activity of DNA. Experiments with 2-ethyl[ 1-\(^{14}\)C]hexanol perfonned with both rats and mice allowed the conclusion tbat most if not all DEHA radioactivity in mouse liver DNA was due to biosynthetic incorporation. A maximum possible true DNA binding by DEHA must be below CBI 0.01. Pretreatment of the animals witb unlabeled compound bad no effect on the DNA radioactivities in either species. The present negative data, in conjunction witb other negative short-term tests for mutagenicity, strongly indicate that covalent interaction with DNA is highly unlikely to be the mode of tumorigenic action of DEHP and DEHA in rodents.}, subject = {Toxikologie}, language = {en} } @article{BoeschFriederichLutzetal.1987, author = {B{\"o}sch, R. and Friederich, U. and Lutz, Werner K. and Brocker, E. and Bachmann, M. and Schlatter, C.}, title = {Investigations on DNA binding in rat liver and in Salmonella and on mutagenicity in the Ames test by emodin, a natural anthraquinone}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60913}, year = {1987}, abstract = {Emodin (1,6,8-trihydroxy-3-methylanthraquinone), an important aglycone found in natural anthraquinone glycosides frequently used in Iaxative drugs, was mutagenic in the Salmonellajmammalian microsome assay (Ames test) with a specificity for strain TA1537. The mutagenic activity was activationdependent with an optimal amount of S9 from Aroclor 1254-treated male Sprague-Dawley rats of 20\% in the S9 mix (v jv) for 10 p.g emodin per plate. Heat inactivation of the S9 for 30 min at 60 ° C prevented mutagenicity. The addition of the cytochrome P-448 inhibitor 7,8-benzoflavone (18.5 nmoles per plate) reduced the mutagenic activity of 5.0 p.g emodin per plate to about one third, whereas the P-450 inhibitor metyrapone (up to 1850 nmoles per plate) was without effect. To test whether a metabolite" binds covalently to Salmonella DNA, [10-\(^{14}\)C]emodin was radiosynthesized, large batches of bacteria were incubated with [10-\(^{14}\)C]emodin and DNA was isolated. [G- \(^{3}\)H]Aflatoxin B1 (AFB1) was used as a positive control mutagen known to act via DNA binding. DNA obtained after aflatoxin treatment could be purified to constant specific activity. With emodin, the specific activity of DNA did not remain constant after repeated precipitations so that it is unlikely that the mutagenicity of emodin is due to covalent interaction of a metabolite with DNA. The antioxidants vitamin C and E or glutathione did not reduce the mutagenicity. Emodin was also negative with strain TA102. Thus, oxygen radicals are probably not involved. When emodin was incubated with S9 alone for up to 50 h before heat-inactivation of the enzymes and addition of bacteria, the mutagenic activity did not decrease. It is concluded that the mutagenicity of emodin is due to a chemically stable, oxidized metabolite forming physico-chemical associations with DNA, possibly of the intercalative type. In order to check whether an intact mammalian organism might be able to activate emodin to a DNA-binding metabolite, radiolabelled emodin was administered by oral gavage to male SD rats and liver DNA was isolated after 72 h. Very little radioactivity was associated with the DNA. Considering that DNA radioactivity could also be due to sources other than covalent interactions, an upper limit for the · covalent binding index, CBI = (p.moles chemical bound per moles DNA nucleotides)/(mmoles chemical administered per kg body weight) of 0.5 is deduced. This is 104 times below the CBI of AFB1. The demonstration of a lack of covalent interaction with DNA bothin Salmonellaandin rat liver is discussed in terms of a reduced hazard posed by emodin as a mutagenic drug in use in humans.}, subject = {Toxikologie}, language = {en} } @article{DaenikenLutzSchlatter1981, author = {D{\"a}niken, A. von and Lutz, Werner K. and Schlatter, C.}, title = {Lack of covalent binding to rat liver DNA of the hypolipidemic drugs clofibrate and fenofibrate}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61087}, year = {1981}, abstract = {\(^{14}\)C-Labelled clofibric acid and fenofibric acid were administered p.o. to 200 g male and female rats. After 10 h, liver nuclear DNA and protein were isolated and the radioactivity was determined. Binding to protein was clearly measurable whereas no binding to DNA could be detected from any drug. A comparison of the Iimit of detection of such DNA binding with well-known chemical carcinogens revealed that the known hepatocarcinogenicity of clofibrate cannot be based upon an initiating, DNA damaging, mode of action but must be due to other, nongenotoxic, mechanisms such as peroxisome proliferation, hepatomegaly, or cytotoxicity due to protein binding. The risk assessment in man and the interpretation of the carcinogenicity data for rodents are discussed.}, subject = {Toxikologie}, language = {en} } @article{LutzSchlatter1977, author = {Lutz, Werner K. and Schlatter, C.}, title = {Mechanism of the carcinogenic action of benzene: irreversible binding to rat liver DNA}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61208}, year = {1977}, abstract = {No abstract available}, subject = {Toxikologie}, language = {en} } @article{MeierBratschiLutzSchlatter1983, author = {Meier-Bratschi, A. and Lutz, Werner K. and Schlatter, C.}, title = {Methylation of liver DNA of rat and mouse by N-nitrosodimethylamine formed in vivo from dimethylamine and nitrite}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-61052}, year = {1983}, abstract = {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.}, subject = {Toxikologie}, language = {en} } @article{ShephardSengstagLutzetal.1993, author = {Shephard, S. E. and Sengstag, C. and Lutz, Werner K. and Schlatter, C.}, title = {Mutations in liver DNA of lacI transgenic mice (Big Blue) following subchronic exposure to 2-acetylaminofluorene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60683}, year = {1993}, abstract = {2-Acetylaminofluorene (2-AAF) was administered at Ievels of 0, 300 and 600 ppm in the diet for 28 days to female transgenic micc bearing the lacl genein a Iambda vector (Big Blue® mice). The Iambda vector was excised from liver DNA and packaged in vitro into bacteriophage particles which were allowed to infect E. coli bacteria, forming plaques on agar plates. Approximately 10\(^5\) plaques wcre screened per animal for the appearance of a bluc colour, indicative of mutations in the lac/ gcnc which had resulted in an inactive gene product. Background mutation rate was 2.7 x 10\(^{-5}\) (pooled results of two animals, 8 mutant plaques/289 530 plaques). At 300 ppm in the diet, the rate of 3.5 X 10\(^{-5}\)(8/236 300) was not significantly increased over background. At 600 ppm in the dict, the rate increased approximately 3 fold to 7.7 x 10\(^{-5}\) (17 /221240). In comparison to the usual single or 5-day carcinogen exposure regimes, the 4-week exposure protocol allowed the use of much lower dose Ievels 00-1000 fold lower). Overt toxicity could thus be avoided. The daily doses used were somewhat higher than those required in 2-year carcinogenicity studies with 2·AAF.}, subject = {Toxikologie}, language = {en} }