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Archives of Toxicology (v.82, #12)
Most cited articles in the Archives of Toxicology: the debate about possibilities and limitations of in vitro toxicity tests and replacement of in vivo studies
by H. M. Bolt; J. G. Hengstler (pp. 881-883).
Most cited articles in the Archives of Toxicology: the debate about possibilities and limitations of in vitro toxicity tests and replacement of in vivo studies
by H. M. Bolt; J. G. Hengstler (pp. 881-883).
Antioxidative effects of statins by Oliver Adam; Ulrich Laufs (pp. 885-892).
Abstract HMG CoA reductase inhibitiors (statins) have been shown to be effective lipid lowering agents and are beneficial in the primary and secondary prevention of coronary heart disease. However, the overall benefits observed with statins appear to be greater than what might be expected from changes in lipid levels alone and the positive effects have only partially been reproduced with other lipid lowering drugs, suggesting effects in addition to cholesterol lowering. In experimental models, many of the cholesterol-independent effects of statins are mediated by inhibition of isoprenoids, which serve as lipid attachments for intracellular signalling molecules such as small Rho guanosine triphosphate-binding proteins, whose membrane localization and function are dependent on isoprenylation. This review summarizes the effects of statins on endothelial function and oxidative stress.
Keywords: Statin; Prevention; Endothelial dysfunction; Oxidative stress; Review
Antioxidative effects of statins by Oliver Adam; Ulrich Laufs (pp. 885-892).
Abstract HMG CoA reductase inhibitiors (statins) have been shown to be effective lipid lowering agents and are beneficial in the primary and secondary prevention of coronary heart disease. However, the overall benefits observed with statins appear to be greater than what might be expected from changes in lipid levels alone and the positive effects have only partially been reproduced with other lipid lowering drugs, suggesting effects in addition to cholesterol lowering. In experimental models, many of the cholesterol-independent effects of statins are mediated by inhibition of isoprenoids, which serve as lipid attachments for intracellular signalling molecules such as small Rho guanosine triphosphate-binding proteins, whose membrane localization and function are dependent on isoprenylation. This review summarizes the effects of statins on endothelial function and oxidative stress.
Keywords: Statin; Prevention; Endothelial dysfunction; Oxidative stress; Review
The influence of diet composition on phase I and II biotransformation enzyme induction by Jaime L. Rudolf; Kathryn A. Bauerly; Eskouhie Tchaparian; Robert B. Rucker; Alyson E. Mitchell (pp. 893-901).
The expression of phase I and II biotransformation enzymes was examined with respect to experimental diet composition and with the addition of the bi-functional inducer flavone. Enzymatic activity and mRNA levels of cytochrome P450 monooxygenase (CYP) isoforms (CYP1A1, CYP1A2, CYP2B1/2) and glutathione-S-transferase (GST) isoforms (GSTA, GSTM, and GSTP) were used as indices for the changes in expression. An amino acid based (AA) diet and a semi-purified egg white (EW) diet were designed to include similar levels of nutrients and were compared to a standard laboratory chow (SC) diet. Rats (Sprague-Dawley) and mice (C57BL/6) were used as animal models. Animals were fed one of the three diets for 7 days prior to incorporation of flavone (2%, wt/wt). Diets with or without flavone were next fed for an additional 3 days. Enzymatic activities of the CYPs in mice and GSTs in both mice and rats were determined. In mice, the relative mRNA levels for each of the CYP and GST isoforms were also measured. The increase in phase I and II enzyme expression observed in response to flavone was most dynamic when the AA-based diet was used (often >20-fold for given isoform enzymatic activities and >200-fold for specific mRNAs), followed by the EW diet (10 to 20-fold and 100 to 200-fold, respectively). The SC diet resulted in a higher level of background expression of CYP and GST isoforms and as a consequence the observed fold increases in CYP and GST isoforms (enzymatic and mRNA levels) were substantially less (1 to 10-fold and 1 to 150-fold. respectively), when the SC diet fed group with or without flavone was compared.
Keywords: Glutathione S-transferase; GST; Cytochrome P450 monooxygenases; CYP; Diet; Flavone; Flavonoids; Enzyme induction
The influence of diet composition on phase I and II biotransformation enzyme induction by Jaime L. Rudolf; Kathryn A. Bauerly; Eskouhie Tchaparian; Robert B. Rucker; Alyson E. Mitchell (pp. 893-901).
The expression of phase I and II biotransformation enzymes was examined with respect to experimental diet composition and with the addition of the bi-functional inducer flavone. Enzymatic activity and mRNA levels of cytochrome P450 monooxygenase (CYP) isoforms (CYP1A1, CYP1A2, CYP2B1/2) and glutathione-S-transferase (GST) isoforms (GSTA, GSTM, and GSTP) were used as indices for the changes in expression. An amino acid based (AA) diet and a semi-purified egg white (EW) diet were designed to include similar levels of nutrients and were compared to a standard laboratory chow (SC) diet. Rats (Sprague-Dawley) and mice (C57BL/6) were used as animal models. Animals were fed one of the three diets for 7 days prior to incorporation of flavone (2%, wt/wt). Diets with or without flavone were next fed for an additional 3 days. Enzymatic activities of the CYPs in mice and GSTs in both mice and rats were determined. In mice, the relative mRNA levels for each of the CYP and GST isoforms were also measured. The increase in phase I and II enzyme expression observed in response to flavone was most dynamic when the AA-based diet was used (often >20-fold for given isoform enzymatic activities and >200-fold for specific mRNAs), followed by the EW diet (10 to 20-fold and 100 to 200-fold, respectively). The SC diet resulted in a higher level of background expression of CYP and GST isoforms and as a consequence the observed fold increases in CYP and GST isoforms (enzymatic and mRNA levels) were substantially less (1 to 10-fold and 1 to 150-fold. respectively), when the SC diet fed group with or without flavone was compared.
Keywords: Glutathione S-transferase; GST; Cytochrome P450 monooxygenases; CYP; Diet; Flavone; Flavonoids; Enzyme induction
Analysis of glutathione S-transferase M1 and glutathione S-transferase T1 gene polymorphisms suggests age-related relationships in a northern Italian population by Alfredo Santovito; Piero Cervella; Claudio Burgarello; Maria Paola Bigatti; Gabriella Sella; Massimiliano DelPero (pp. 903-907).
The present work attempts to determine the distribution of GSTM1 and GSTT1 genotype and allele frequencies in a sample of northern Italian population, and to examine the age-related association of these polymorphisms. The frequencies of the deleted GSTM1 and GSTT1 genotypes were 0.357 and 0.169, respectively. GSTT1 null-genotype frequency found in this work further confirms data obtained in previous studies of Italian populations, while for GSTM1 deletion our sample showed a significantly lower-frequency value with respect to other Italian and European populations, with exception of the Greek. No significant differences occurred between men and women in the frequency of each gene, which could suggest that, in the studied sample, there were no sex differences in susceptibility to diseases and in detoxifying enzymes such as GSTs. In order to analyze the relationship between GSTT1 and GSTM1 gene polymorphisms and age, the sample was subdivided into four age groups: 1–30 years (n = 101); 31–50 years (n = 160); 51–79 years (n = 144) and 80–100 years (n = 58). This age-related analysis showed a decreasing gradient of GSTs null genotypes between younger and older groups, with the 80–100 age group showing a significantly lower frequency of GSTT1 null, GSTM1 null and GSTT1/GSTM1 double null genotypes with respect to the younger group.
Keywords: Genetic polymorphism; GSTM1; GSTT1; Italy; Ageing
Analysis of glutathione S-transferase M1 and glutathione S-transferase T1 gene polymorphisms suggests age-related relationships in a northern Italian population by Alfredo Santovito; Piero Cervella; Claudio Burgarello; Maria Paola Bigatti; Gabriella Sella; Massimiliano DelPero (pp. 903-907).
The present work attempts to determine the distribution of GSTM1 and GSTT1 genotype and allele frequencies in a sample of northern Italian population, and to examine the age-related association of these polymorphisms. The frequencies of the deleted GSTM1 and GSTT1 genotypes were 0.357 and 0.169, respectively. GSTT1 null-genotype frequency found in this work further confirms data obtained in previous studies of Italian populations, while for GSTM1 deletion our sample showed a significantly lower-frequency value with respect to other Italian and European populations, with exception of the Greek. No significant differences occurred between men and women in the frequency of each gene, which could suggest that, in the studied sample, there were no sex differences in susceptibility to diseases and in detoxifying enzymes such as GSTs. In order to analyze the relationship between GSTT1 and GSTM1 gene polymorphisms and age, the sample was subdivided into four age groups: 1–30 years (n = 101); 31–50 years (n = 160); 51–79 years (n = 144) and 80–100 years (n = 58). This age-related analysis showed a decreasing gradient of GSTs null genotypes between younger and older groups, with the 80–100 age group showing a significantly lower frequency of GSTT1 null, GSTM1 null and GSTT1/GSTM1 double null genotypes with respect to the younger group.
Keywords: Genetic polymorphism; GSTM1; GSTT1; Italy; Ageing
Pharmacologic profiling of human and rat cytochrome P450 1A1 and 1A2 induction and competition by Walter M. A. Westerink; Joe C. R. Stevenson; Willem G. E. J. Schoonen (pp. 909-921).
Strong activation of the AhR can lead to various toxic effects such as (non-genotoxic) carcinogenicity. Moreover, drug–drug interactions by non- or competitive inhibition of CYP1A1 and 1A2 may cause adverse side effects. Normally the majority of toxicity studies are performed in rats, while for the prediction of human toxicity human AhR activation and CYP1A competition should be studied. The present study focused on the deselection of strong AhR activators and/or CYP1A inducers and (non-)competitive inhibitors in the early phase of drug development, as well as on species differences between humans and rats. Induction studies were performed in the human HepG2 and rat H4IIE cell lines. A set of 119 compounds, including known AhR ligands were tested. CYP1A induction was observed for 24 compounds. In H4IIE cells, more compounds showed induction and most EC50 values were below those of HepG2 cells. Species specific CYP1A induction in H4IIE and HepG2 cells was obtained for eight and three compounds, respectively. The same compounds except four in-house NCEs were used to study differences between CYP1A1 and 1A2 competition in human and rat supersomes. Of the 115 compounds 46 showed CYP1A1 competition. Competition was human and rat specific for 12 and 10 compounds, respectively. CYP1A2 competition was observed for 37 compounds of which 14 and 3 compounds showed human and rat specific inhibition, respectively. In conclusion, for several compounds species differences between CYP1A induction and competition in human and rat were found. Therefore, parallel screening in both species might be a very useful strategy.
Keywords: Aryl hydrocarbon receptor; CYP1A; Induction; Competition; HepG2; H4IIE
Pharmacologic profiling of human and rat cytochrome P450 1A1 and 1A2 induction and competition by Walter M. A. Westerink; Joe C. R. Stevenson; Willem G. E. J. Schoonen (pp. 909-921).
Strong activation of the AhR can lead to various toxic effects such as (non-genotoxic) carcinogenicity. Moreover, drug–drug interactions by non- or competitive inhibition of CYP1A1 and 1A2 may cause adverse side effects. Normally the majority of toxicity studies are performed in rats, while for the prediction of human toxicity human AhR activation and CYP1A competition should be studied. The present study focused on the deselection of strong AhR activators and/or CYP1A inducers and (non-)competitive inhibitors in the early phase of drug development, as well as on species differences between humans and rats. Induction studies were performed in the human HepG2 and rat H4IIE cell lines. A set of 119 compounds, including known AhR ligands were tested. CYP1A induction was observed for 24 compounds. In H4IIE cells, more compounds showed induction and most EC50 values were below those of HepG2 cells. Species specific CYP1A induction in H4IIE and HepG2 cells was obtained for eight and three compounds, respectively. The same compounds except four in-house NCEs were used to study differences between CYP1A1 and 1A2 competition in human and rat supersomes. Of the 115 compounds 46 showed CYP1A1 competition. Competition was human and rat specific for 12 and 10 compounds, respectively. CYP1A2 competition was observed for 37 compounds of which 14 and 3 compounds showed human and rat specific inhibition, respectively. In conclusion, for several compounds species differences between CYP1A induction and competition in human and rat were found. Therefore, parallel screening in both species might be a very useful strategy.
Keywords: Aryl hydrocarbon receptor; CYP1A; Induction; Competition; HepG2; H4IIE
Primary rat hepatocytes as in vitro system for gene expression studies: comparison of sandwich, Matrigel and 2D cultures by M. Schug; T. Heise; A. Bauer; D. Storm; M. Blaszkewicz; E. Bedawy; M. Brulport; B. Geppert; M. Hermes; W. Föllmann; K. Rapp; L. Maccoux; W. Schormann; K. E. Appel; A. Oberemm; U. Gundert-Remy; J. G. Hengstler (pp. 923-931).
Recent studies have presented evidence that in vivo obtained gene expression data can be used for carcinogen classification, for instance to differentiate between genotoxic and non-genotoxic carcinogens. However, although primary rat hepatocytes represent a well-established in vitro system for drug metabolism and enzyme induction, they have not yet been systematically optimized for toxicogenomic studies. The latter may be confounded by the fact that cultured hepatocytes show strong spontaneous alterations in gene expression patterns. Therefore, we addressed the following questions: (1) which culture system is optimal, comparing sandwich, Matrigel and 2D cultures, (2) how critical is the impact of culture period on substance-induced alterations in gene expression and (3) do these substance-induced alterations in cultured hepatocytes occur already at in vivo relevant concentrations? For this purpose we analyzed the expression of four genes, namely Abat, Gsk3β, Myd116 and Sult1a1 that recently have been reported to be influenced by the antihistamine and non-genotoxic carcinogen methapyrilene (MPy). The most reproducible effects of MPy were observed in sandwich cultures. Induction factors of Gsk3β and Myd116 at 100 μM MPy were 2 and 4 (medians), respectively, whereas expression of Abat and Sult1a1 were inhibited by factors of 7 and 5, respectively. Similar results were observed in hepatocytes maintained for 24 h or 3 weeks in sandwich culture with respect to the influence of MPy on the expression of Abat, Gsk3β, Myd116 and Sult1a1. To determine whether MPy influences gene expression at in vivo relevant concentrations, 3.5 mg/kg MPy were administered to male Wistar rats intraperitoneally, resulting in plasma concentrations ranging between 1.72 and 0.32 μM 5 and 80 min after injection. Inhibition of Abat and Sult1a1 expression in vitro already occurred at in vivo relevant concentrations of 0.39 μM MPy. Induction of Myd116 was observed at 6.25 μM which is higher but in the same order of magnitude as in vivo relevant concentrations. In conclusion, the presented data strongly suggest that sandwich cultures are most adequate for detection of MPy-induced gene expression alterations and the effect of MPy was detected at in vivo relevant concentrations.
Keywords: Toxicogenomics; In vitro system; Primary rat hepatocytes; Nongenotoxic carcinogen; Methapyrilene; Sandwich culture
Primary rat hepatocytes as in vitro system for gene expression studies: comparison of sandwich, Matrigel and 2D cultures by M. Schug; T. Heise; A. Bauer; D. Storm; M. Blaszkewicz; E. Bedawy; M. Brulport; B. Geppert; M. Hermes; W. Föllmann; K. Rapp; L. Maccoux; W. Schormann; K. E. Appel; A. Oberemm; U. Gundert-Remy; J. G. Hengstler (pp. 923-931).
Recent studies have presented evidence that in vivo obtained gene expression data can be used for carcinogen classification, for instance to differentiate between genotoxic and non-genotoxic carcinogens. However, although primary rat hepatocytes represent a well-established in vitro system for drug metabolism and enzyme induction, they have not yet been systematically optimized for toxicogenomic studies. The latter may be confounded by the fact that cultured hepatocytes show strong spontaneous alterations in gene expression patterns. Therefore, we addressed the following questions: (1) which culture system is optimal, comparing sandwich, Matrigel and 2D cultures, (2) how critical is the impact of culture period on substance-induced alterations in gene expression and (3) do these substance-induced alterations in cultured hepatocytes occur already at in vivo relevant concentrations? For this purpose we analyzed the expression of four genes, namely Abat, Gsk3β, Myd116 and Sult1a1 that recently have been reported to be influenced by the antihistamine and non-genotoxic carcinogen methapyrilene (MPy). The most reproducible effects of MPy were observed in sandwich cultures. Induction factors of Gsk3β and Myd116 at 100 μM MPy were 2 and 4 (medians), respectively, whereas expression of Abat and Sult1a1 were inhibited by factors of 7 and 5, respectively. Similar results were observed in hepatocytes maintained for 24 h or 3 weeks in sandwich culture with respect to the influence of MPy on the expression of Abat, Gsk3β, Myd116 and Sult1a1. To determine whether MPy influences gene expression at in vivo relevant concentrations, 3.5 mg/kg MPy were administered to male Wistar rats intraperitoneally, resulting in plasma concentrations ranging between 1.72 and 0.32 μM 5 and 80 min after injection. Inhibition of Abat and Sult1a1 expression in vitro already occurred at in vivo relevant concentrations of 0.39 μM MPy. Induction of Myd116 was observed at 6.25 μM which is higher but in the same order of magnitude as in vivo relevant concentrations. In conclusion, the presented data strongly suggest that sandwich cultures are most adequate for detection of MPy-induced gene expression alterations and the effect of MPy was detected at in vivo relevant concentrations.
Keywords: Toxicogenomics; In vitro system; Primary rat hepatocytes; Nongenotoxic carcinogen; Methapyrilene; Sandwich culture
Munich Oktoberfest experience: remarkable impact of sex and age in ethanol intoxication by C. Binner; S. Selinski; M. J. Barysch; C. Pölcher; Wiebke Schormann; Matthias Hermes; Marc Brulport; Alexander Bauer; Claudia Rudolph; Essam Bedawy; Markus Schug; Klaus Golka; D. Hasenclever; H. Trauer; R. Lessig; H. M. Bolt; K. Ickstadt; Jan Georg Hengstler (pp. 933-939).
Approximately 5,000 of 6 million annual visitors of the Oktoberfest in Munich have to undergo medical treatment. Patients with alcohol intoxication without trauma or further complications are all treated in a specialized medical camp. We studied these patients in order to identify risk factors and to assess the relevance of the Glasgow Coma Score (GCS) and of ethanol blood concentrations for patient management. In 2004 totally 405 patients suffering from ethanol intoxication without trauma were treated in the medical camp. A complete set of the following data was obtained from all 405 patients: GCS, ethanol blood concentration, age, sex, blood pressure (mean, systolic and diastolic), body temperature, heart rate, blood sugar, GOT, γ-GT, and CK. A multivariate logistic regression model was applied to identify risk factors predicting patients at increased risk of hospitalization. Low GCS (≤8 vs. >8, OR: 4.18, CI: 1.96–8.65) low age (20–29 vs. ≥30 years, OR: 2.35, CI: 1.05–5.65) and male gender (male vs. female, OR: 3.58, CI: 1.36–9.34) independently predicted patients that had to be hospitalized. All other parameters including ethanol blood concentrations were not explanatory. Patients with GCS ≤ 8 (n = 66) had a lower median blood pressure (P = 0.0312) and showed a smaller increase in blood pressure during the observation period compared to patients with GCS > 8 (P < 0.001), suggesting that this subgroup may require longer recovery periods. Men aged 20–29 years were at highest risk for hospital admission. Increased risk could not be explained by higher ethanol blood concentrations in this subgroup. Importantly, GCS < 6 does not justify endotracheal intubation in ethanol intoxicated patients, when further complications, such as trauma, can be excluded.
Keywords: Ethanol intoxication; Glasgow coma score; Hospitalization; Endotracheal intubation; Acute alcohol intoxication
Munich Oktoberfest experience: remarkable impact of sex and age in ethanol intoxication by C. Binner; S. Selinski; M. J. Barysch; C. Pölcher; Wiebke Schormann; Matthias Hermes; Marc Brulport; Alexander Bauer; Claudia Rudolph; Essam Bedawy; Markus Schug; Klaus Golka; D. Hasenclever; H. Trauer; R. Lessig; H. M. Bolt; K. Ickstadt; Jan Georg Hengstler (pp. 933-939).
Approximately 5,000 of 6 million annual visitors of the Oktoberfest in Munich have to undergo medical treatment. Patients with alcohol intoxication without trauma or further complications are all treated in a specialized medical camp. We studied these patients in order to identify risk factors and to assess the relevance of the Glasgow Coma Score (GCS) and of ethanol blood concentrations for patient management. In 2004 totally 405 patients suffering from ethanol intoxication without trauma were treated in the medical camp. A complete set of the following data was obtained from all 405 patients: GCS, ethanol blood concentration, age, sex, blood pressure (mean, systolic and diastolic), body temperature, heart rate, blood sugar, GOT, γ-GT, and CK. A multivariate logistic regression model was applied to identify risk factors predicting patients at increased risk of hospitalization. Low GCS (≤8 vs. >8, OR: 4.18, CI: 1.96–8.65) low age (20–29 vs. ≥30 years, OR: 2.35, CI: 1.05–5.65) and male gender (male vs. female, OR: 3.58, CI: 1.36–9.34) independently predicted patients that had to be hospitalized. All other parameters including ethanol blood concentrations were not explanatory. Patients with GCS ≤ 8 (n = 66) had a lower median blood pressure (P = 0.0312) and showed a smaller increase in blood pressure during the observation period compared to patients with GCS > 8 (P < 0.001), suggesting that this subgroup may require longer recovery periods. Men aged 20–29 years were at highest risk for hospital admission. Increased risk could not be explained by higher ethanol blood concentrations in this subgroup. Importantly, GCS < 6 does not justify endotracheal intubation in ethanol intoxicated patients, when further complications, such as trauma, can be excluded.
Keywords: Ethanol intoxication; Glasgow coma score; Hospitalization; Endotracheal intubation; Acute alcohol intoxication
In utero and postnatal exposure to a phytoestrogen-enriched diet increases parameters of acute inflammation in a rat model of TNBS-induced colitis by Jan Seibel; Almut F. Molzberger; Torsten Hertrampf; Ute Laudenbach-Leschowski; Gisela H. Degen; Patrick Diel (pp. 941-950).
Inflammatory bowel disease (IBD) is very common in Europe and USA. Its incidence in East Asia has been traditionally low, albeit the risk of IBD increases in Asian immigrants adopting western lifestyles, suggesting a strong role of environmental/dietary factors in IBD. A lifelong exposure to phytoestrogen-rich diets has been associated with a decreased risk of developing breast cancer and might also be protective against IBD. We studied the influence of in utero and postnatal exposure to a phytoestrogen (PE)-rich diet on acute inflammation in an animal model of TNBS-induced colitis. Wistar rats were exposed in utero and postnatally to high (genistein: 240 μg/g feed; daidzein: 232 μg/g feed) or very low levels (genistein and daidzein <10 μg/g feed) of phytoestrogen isoflavones fed to pregnant dams with the diet and throughout nursing. After weaning, the offspring had free access to these diets. At the age of 11 weeks, colitis was induced with an enema of TNBS. After 3 days, animals were sacrificed and tissues were collected for histological evaluation and analysis of molecular markers of inflammation. Animals kept on a PE-rich diet (PRD) had higher colon weights than animals on low PE-levels (PDD), suggesting enhanced acute inflammation by phytoestrogens. This result was supported by histological findings and by analysis of myeloperoxidase activity. Interestingly, relative mRNA and protein expression of cyclooxygenase-2 (COX-2) were modulated in rats on PRD, providing evidence that COX-2, the inducible isoform of the enzyme, is involved in the management of colonic inflammation. Our results suggest that early-in-life exposure to PE might not protect against the development of IBD but enhances the extent of acute inflammation.
Keywords: Colitis; IBD; Phytoestrogens; TNBS; COX-2; Inflammation; Isoflavones
In utero and postnatal exposure to a phytoestrogen-enriched diet increases parameters of acute inflammation in a rat model of TNBS-induced colitis by Jan Seibel; Almut F. Molzberger; Torsten Hertrampf; Ute Laudenbach-Leschowski; Gisela H. Degen; Patrick Diel (pp. 941-950).
Inflammatory bowel disease (IBD) is very common in Europe and USA. Its incidence in East Asia has been traditionally low, albeit the risk of IBD increases in Asian immigrants adopting western lifestyles, suggesting a strong role of environmental/dietary factors in IBD. A lifelong exposure to phytoestrogen-rich diets has been associated with a decreased risk of developing breast cancer and might also be protective against IBD. We studied the influence of in utero and postnatal exposure to a phytoestrogen (PE)-rich diet on acute inflammation in an animal model of TNBS-induced colitis. Wistar rats were exposed in utero and postnatally to high (genistein: 240 μg/g feed; daidzein: 232 μg/g feed) or very low levels (genistein and daidzein <10 μg/g feed) of phytoestrogen isoflavones fed to pregnant dams with the diet and throughout nursing. After weaning, the offspring had free access to these diets. At the age of 11 weeks, colitis was induced with an enema of TNBS. After 3 days, animals were sacrificed and tissues were collected for histological evaluation and analysis of molecular markers of inflammation. Animals kept on a PE-rich diet (PRD) had higher colon weights than animals on low PE-levels (PDD), suggesting enhanced acute inflammation by phytoestrogens. This result was supported by histological findings and by analysis of myeloperoxidase activity. Interestingly, relative mRNA and protein expression of cyclooxygenase-2 (COX-2) were modulated in rats on PRD, providing evidence that COX-2, the inducible isoform of the enzyme, is involved in the management of colonic inflammation. Our results suggest that early-in-life exposure to PE might not protect against the development of IBD but enhances the extent of acute inflammation.
Keywords: Colitis; IBD; Phytoestrogens; TNBS; COX-2; Inflammation; Isoflavones
Oral administration of potassium dichromate inhibits brush border membrane enzymes and alters anti-oxidant status of rat intestine by N. A. Arivarasu; Sabiha Fatima; Riaz Mahmood (pp. 951-958).
Potassium dichromate (K2Cr2O7) is a soluble hexavalent chromium compound that is widely used in several industries. In the present work the effect of administration of K2Cr2O7 on rat intestinal brush border membrane (BBM) enzymes and anti-oxidant system was studied. Rats were given a single oral dose of K2Cr2O7 (100 mg/kg body weight) and sacrificed 6, 12, 24, 48 and 96 h after the treatment. Control animals were not given K2Cr2O7. The administration of K2Cr2O7 resulted in a reversible decline in the specific activities of several BBM enzymes. The decrease in the activities of these enzymes was due to changes in the maximum velocity while their affinities for the substrates remained unchanged. Lipid peroxidation increased while total SH groups decreased in K2Cr2O7-treated rats as compared to controls indicating increased oxidative stress in the intestinal mucosa. The activities of superoxide dismutase and glutathione-S-transferase increased while those of catalase, glutathione reductase, thioredoxin reductase and glucose-6-phosphate dehydrogenase decreased. The maximum changes in all the parameters studied above were 24 h after administration of K2Cr2O7 after which recovery took place, in most cases almost to control values after 96 h. These results show that oral administration of K2Cr2O7 to decrease in the activities of BBM enzymes, increase in oxidative stress and alters the activities of anti-oxidant enzymes in rat intestine.
Keywords: Potassium dichromate; Intestine; Brush border membrane; Oxidative stress
Oral administration of potassium dichromate inhibits brush border membrane enzymes and alters anti-oxidant status of rat intestine by N. A. Arivarasu; Sabiha Fatima; Riaz Mahmood (pp. 951-958).
Potassium dichromate (K2Cr2O7) is a soluble hexavalent chromium compound that is widely used in several industries. In the present work the effect of administration of K2Cr2O7 on rat intestinal brush border membrane (BBM) enzymes and anti-oxidant system was studied. Rats were given a single oral dose of K2Cr2O7 (100 mg/kg body weight) and sacrificed 6, 12, 24, 48 and 96 h after the treatment. Control animals were not given K2Cr2O7. The administration of K2Cr2O7 resulted in a reversible decline in the specific activities of several BBM enzymes. The decrease in the activities of these enzymes was due to changes in the maximum velocity while their affinities for the substrates remained unchanged. Lipid peroxidation increased while total SH groups decreased in K2Cr2O7-treated rats as compared to controls indicating increased oxidative stress in the intestinal mucosa. The activities of superoxide dismutase and glutathione-S-transferase increased while those of catalase, glutathione reductase, thioredoxin reductase and glucose-6-phosphate dehydrogenase decreased. The maximum changes in all the parameters studied above were 24 h after administration of K2Cr2O7 after which recovery took place, in most cases almost to control values after 96 h. These results show that oral administration of K2Cr2O7 to decrease in the activities of BBM enzymes, increase in oxidative stress and alters the activities of anti-oxidant enzymes in rat intestine.
Keywords: Potassium dichromate; Intestine; Brush border membrane; Oxidative stress
Drug metabolizing enzyme induction pathways in experimental non-alcoholic steatohepatitis by Craig D. Fisher; Jonathan P. Jackson; Andrew J. Lickteig; Lisa M. Augustine; Nathan J. Cherrington (pp. 959-964).
Non-alcoholic steatohepatitis (NASH) is a disease that compromises hepatic function and the capacity to metabolize numerous drugs. Aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR), pregnane X receptor (PXR), peroxisome proliferator-activated receptor alpha (PPARα), and nuclear factor-E2 related factor 2 (Nrf2) are xenobiotic activated transcription factors that regulate induction of a number of drug metabolizing enzymes (DMEs). The purpose of the current study was to determine whether experimental NASH alters the xenobiotic activation of these transcription factors and induction of downstream DME targets Cyp1A1, Cyp2B10, Cyp3A11, Cyp4A14 and NAD(P)H:quinone oxidoreductase 1 (Nqo1), respectively. Mice fed normal rodent chow or methionine-choline-deficient (MCD) diet for 8 weeks were then treated with microsomal enzyme inducers β-naphoflavone (BNF), 1,4-bis-[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP), pregnenolone-16α-carbonitrile (PCN), clofibrate (CFB) or oltipraz (OPZ), known activators of AhR, CAR, PXR, PPARα and Nrf2, respectively. Results of this study show that (1) Hepatic PXR mRNA levels were significantly increased (1.4-fold) in mice fed MCD diet, while AhR, CAR, PPARα and Nrf2 were not affected. (2) The MCD diet did not alter hepatic inducibility of Cyp1A1, Cyp2B10, Cyp3A11 mRNA levels by their respective microsomal inducers. (3) Constitutive levels of Cyp4A14 mRNA were significantly increased in mice fed the MCD diet, yet further induction by clofibrate was not observed. (4) Hepatic Nqo1 mRNA levels were significantly increased by the MCD diet; however, additional induction of Nqo1 was still achievable following treatment with the Nrf2 activator OPZ.
Keywords: Non-alcoholic fatty liver disease; Xenobiotic activated receptors; Drug metabolizing enzyme induction; Cytochrome P450 enzymes and NAD(P)H:quinone oxidoreductase 1
Drug metabolizing enzyme induction pathways in experimental non-alcoholic steatohepatitis by Craig D. Fisher; Jonathan P. Jackson; Andrew J. Lickteig; Lisa M. Augustine; Nathan J. Cherrington (pp. 959-964).
Non-alcoholic steatohepatitis (NASH) is a disease that compromises hepatic function and the capacity to metabolize numerous drugs. Aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR), pregnane X receptor (PXR), peroxisome proliferator-activated receptor alpha (PPARα), and nuclear factor-E2 related factor 2 (Nrf2) are xenobiotic activated transcription factors that regulate induction of a number of drug metabolizing enzymes (DMEs). The purpose of the current study was to determine whether experimental NASH alters the xenobiotic activation of these transcription factors and induction of downstream DME targets Cyp1A1, Cyp2B10, Cyp3A11, Cyp4A14 and NAD(P)H:quinone oxidoreductase 1 (Nqo1), respectively. Mice fed normal rodent chow or methionine-choline-deficient (MCD) diet for 8 weeks were then treated with microsomal enzyme inducers β-naphoflavone (BNF), 1,4-bis-[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP), pregnenolone-16α-carbonitrile (PCN), clofibrate (CFB) or oltipraz (OPZ), known activators of AhR, CAR, PXR, PPARα and Nrf2, respectively. Results of this study show that (1) Hepatic PXR mRNA levels were significantly increased (1.4-fold) in mice fed MCD diet, while AhR, CAR, PPARα and Nrf2 were not affected. (2) The MCD diet did not alter hepatic inducibility of Cyp1A1, Cyp2B10, Cyp3A11 mRNA levels by their respective microsomal inducers. (3) Constitutive levels of Cyp4A14 mRNA were significantly increased in mice fed the MCD diet, yet further induction by clofibrate was not observed. (4) Hepatic Nqo1 mRNA levels were significantly increased by the MCD diet; however, additional induction of Nqo1 was still achievable following treatment with the Nrf2 activator OPZ.
Keywords: Non-alcoholic fatty liver disease; Xenobiotic activated receptors; Drug metabolizing enzyme induction; Cytochrome P450 enzymes and NAD(P)H:quinone oxidoreductase 1
Genotoxicity of sludges, wastewater and effluents from three different industries by K. Krishnamurthi; S. Saravana Devi; J. G. Hengstler; Matthias Hermes; Koel Kumar; Dipanwita Dutta; S. Muhil Vannan; T. S. Subin; R. R. Yadav; T. Chakrabarti (pp. 965-971).
Many surface waters in Europe, Asia and South America have been reported to be contaminated with genotoxic substances. Therefore, it is important to establish strategies for identification of the most critical sources. In this study, we used a battery of four genotoxicity assays namely chromosomal aberration, DNA strand break, DNA laddering and P53 accumulation tests in mononuclear blood cells. Before cleaning of wastewater high levels of genotoxic contamination could be observed. For instance, we observed an increase in chromosomal aberrations from 2.6 ± 1.1 (aberrant cells in %; control), to 33.6 ± 6.6 in a petrochemical plant, 29.4 ± 3.3 in a petroleum refinery and 14.4 ± 1.8 in a coke plant of steel industry. A good correlation between the four assays was found. The most sensitive and reproducible results were obtained with the chromosomal aberration assay. Interestingly, clear differences in the efficiency of wastewater cleaning in three different treatment plants were observed. The first and second treatment plants in petrochemical industry and coke plant of steel industry completely eliminated genotoxicity of the wastewater. However, the third plant in petroleum refinery could achieve a reduction in genotoxicity but significant genotoxic contaminations were still present. In conclusion, our battery of genotoxicity tests allows the identification of critical sources contributing to contamination of surface waters.
Keywords: Effluent treatment plant; Wastewater; Effluent extract; Genotoxicity; Polycyclic aromatic hydrocarbons; Wastewater extract
Genotoxicity of sludges, wastewater and effluents from three different industries by K. Krishnamurthi; S. Saravana Devi; J. G. Hengstler; Matthias Hermes; Koel Kumar; Dipanwita Dutta; S. Muhil Vannan; T. S. Subin; R. R. Yadav; T. Chakrabarti (pp. 965-971).
Many surface waters in Europe, Asia and South America have been reported to be contaminated with genotoxic substances. Therefore, it is important to establish strategies for identification of the most critical sources. In this study, we used a battery of four genotoxicity assays namely chromosomal aberration, DNA strand break, DNA laddering and P53 accumulation tests in mononuclear blood cells. Before cleaning of wastewater high levels of genotoxic contamination could be observed. For instance, we observed an increase in chromosomal aberrations from 2.6 ± 1.1 (aberrant cells in %; control), to 33.6 ± 6.6 in a petrochemical plant, 29.4 ± 3.3 in a petroleum refinery and 14.4 ± 1.8 in a coke plant of steel industry. A good correlation between the four assays was found. The most sensitive and reproducible results were obtained with the chromosomal aberration assay. Interestingly, clear differences in the efficiency of wastewater cleaning in three different treatment plants were observed. The first and second treatment plants in petrochemical industry and coke plant of steel industry completely eliminated genotoxicity of the wastewater. However, the third plant in petroleum refinery could achieve a reduction in genotoxicity but significant genotoxic contaminations were still present. In conclusion, our battery of genotoxicity tests allows the identification of critical sources contributing to contamination of surface waters.
Keywords: Effluent treatment plant; Wastewater; Effluent extract; Genotoxicity; Polycyclic aromatic hydrocarbons; Wastewater extract
Synergism of aromatic amines and benzo[a]pyrene in induction of Ah receptor-dependent genes by Alexandra Borza; Sabine Plöttner; Alexander Wolf; Claudia Behm; Silvia Selinski; Jan G. Hengstler; Peter H. Roos; Hermann M. Bolt; Jürgen Kuhlmann; Wolfram Föllmann (pp. 973-980).
Aromatic amines have been shown to cause bladder cancer. However, epithelial cells of the urinary bladder, cells of origin of bladder cancer, may be exposed to numerous substances besides aromatic amines. In the present study, we analysed possible interactions between the aromatic amines 4-aminobiphenyl (4-ABP) as well as 2-naphthylamine (2-NA) and the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P). For this purpose we incubated primary porcine urinary bladder epithelial cells (PUBEC) with concentrations of 1 to 50 μM 4-ABP with and without co-exposure to B[a]P. As expected B[a]P increased mRNA expression of cytochrome P450 1A1 (CYP1A1), whereas 4-ABP had no effect. However, when co-exposed 4-ABP enhanced the induction of CYP1A1 by B[a]P. This result was confirmed by Western blot analysis of CYP1A1 protein expression. A similar effect as for CYP1A1 was also observed for cyclooxygenase-2 (COX-2) and UDP-glucuronosyltransferase 1 (UGT1). Next, we studied co-exposures of 2-NA and B[a]P. Similar as for 4-ABP also 2-NA enhanced B[a]P-mediated induction of CYP1A1. Our results demonstrate that some aromatic amines may enhance the influence of B[a]P on Ah receptor-dependent genes.
Keywords: Bladder cancer; Combination effects; Aromatic amines; Polycyclic aromatic hydrocarbons; Xenobiotic metabolising enzymes; CYP1A1 induction; PUBEC
Synergism of aromatic amines and benzo[a]pyrene in induction of Ah receptor-dependent genes by Alexandra Borza; Sabine Plöttner; Alexander Wolf; Claudia Behm; Silvia Selinski; Jan G. Hengstler; Peter H. Roos; Hermann M. Bolt; Jürgen Kuhlmann; Wolfram Föllmann (pp. 973-980).
Aromatic amines have been shown to cause bladder cancer. However, epithelial cells of the urinary bladder, cells of origin of bladder cancer, may be exposed to numerous substances besides aromatic amines. In the present study, we analysed possible interactions between the aromatic amines 4-aminobiphenyl (4-ABP) as well as 2-naphthylamine (2-NA) and the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P). For this purpose we incubated primary porcine urinary bladder epithelial cells (PUBEC) with concentrations of 1 to 50 μM 4-ABP with and without co-exposure to B[a]P. As expected B[a]P increased mRNA expression of cytochrome P450 1A1 (CYP1A1), whereas 4-ABP had no effect. However, when co-exposed 4-ABP enhanced the induction of CYP1A1 by B[a]P. This result was confirmed by Western blot analysis of CYP1A1 protein expression. A similar effect as for CYP1A1 was also observed for cyclooxygenase-2 (COX-2) and UDP-glucuronosyltransferase 1 (UGT1). Next, we studied co-exposures of 2-NA and B[a]P. Similar as for 4-ABP also 2-NA enhanced B[a]P-mediated induction of CYP1A1. Our results demonstrate that some aromatic amines may enhance the influence of B[a]P on Ah receptor-dependent genes.
Keywords: Bladder cancer; Combination effects; Aromatic amines; Polycyclic aromatic hydrocarbons; Xenobiotic metabolising enzymes; CYP1A1 induction; PUBEC