bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction of micronuclei and toxic effects in embryos of pregnant rats treated before implantation with anticancer drugs: Cyclophosphamide, Cis‐platinum, adriamycin
Authors: Giavini E. , Lemonica I. P. , Lou Y. , Broccia M. L. , Prati M.
Published: February 2006

To evaluate a possible relationship of maternal exposure to anticancer drugs during the preimplantation period to blastopathies and postimplantation embryotoxicity, CD female rats were injected intraperitoneally on day 3 of pregnancy with 15 and 30 mg/kg of cyclophosphamide (CPA), 2 and 4 mg/kg of Adriamycin (ADR), 3 and 6 mg/kg of cis‐platinum (Cis‐Pt), or with 5 ml/kg of saline. Blastocysts were collected on day 5 of gestation and evaluated for gross morphology, cell number, and micronuclei. Some females were sacrificed on day 21 of pregnancy in order to evaluate postimplantation embryotoxicity. A reduction in cell number/blastocyst was observed only in animals exposed to Cis‐Pt 6 mg/kg; vice versa, a dose‐related increase of micronuclei and of blastocysts with micronuclei was found in all groups treated with the anticancer agents. A significant increase of postimplantation loss was recorded in the groups treated with high doses of Cis‐Pt and ADR, but no clear signs of teratogenicity were observed.
Analysis of the mechanism of isoniazid‐induced developmental toxicity with frog embryo teratogenesis assay: Xenopus (FETAX)
Authors: Fort Douglas J. , Bantle John A.
Published: February 2006

The developmental toxicity of isoniazid (INH) and the metabolites acetylhydrazide (AH) and isonicotinic acid (INA) were examined with the frog embryo teratogenesis assay‐Xenopus (FETAX). Late Xenopus laevis blastulae were exposed to INH, AH, and INA for 96 h in two separate static‐renewal tests with and without the presence of three differently induced metabolic activation systems (MAS). The MAS consisted of uninduced, Aroclor 1254‐induced, and INH‐induced rat liver microsomes. Addition of the INH‐induced MAS decreased the 96 h LC50 of INH and AH approximately 1.6‐fold and 7.9‐fold, respectively. The 96 h EC50 (malformation) of INH was virtually unaffected; however, the INH‐MAS decreased the teratogenic index (TI) [96 h LC50/96 h EC50 (malformation)] nearly 1.8‐fold. The 96 h EC50 (malformation) of AH increased approximately 2.0‐fold, decreasing the teratogenic index value 15.8‐fold. INA yielded a teratogenic index value of 2.5. Neither the uninduced MAS nor the Aroclor 1254‐induced MAS had an effect on any of the compounds tested and none of the MAS affected the developmental toxicity of INA. Results from this study suggest that mixed functional oxidase metabolism may alter the developmental toxicity of INH in vitro by producing a more embryolethal, but less teratogenic metabolite(s) than INH or AH themselves. Results are indicative of the utility and versatility of FETAX in evaluating toxicological mechanisms of teratogenesis in vitro.
Induction of fetal malformations after treatment of mouse embryos with methylnitrosourea at the preimplantation stages
Authors: Nagao Tetsuji , Morita Yasunobu , Ishizuka Yasuo , Wada Azusa , Mizutani Masahiro
Published: February 2006

The effects of methylnitrosourea (MNU) on the development of preimplantation mouse embryos were investigated in this study. ICR mice were treated intraperitoneally with single doses of 10, 20, and 30 mg MNU/kg body wt on day 0, 1, 2, or 3 of pregnancy. The uterine contents were examined on day 18 of pregnancy. The fetuses were examined for external and skeletal abnormalities. No significant differences were observed in the number of implantation sites between all the MNU‐treated groups and controls. MNU treatment on day 2 or 3 of pregnancy caused dose‐dependent significant increases in the incidence of abnormal fetuses over the control level, while treatment on day 0 or 1 failed to cause an increase of abnormalities. Cleft palate, exencephalus, and malformed vertebrae were the most common types of abnormalities. In the embryo transfer experiments, the frequency of fetal abnormalities induced when embryos were transferred from MNU‐treated females to untreated pseudopregnant females was significantly higher than that induced when embryos were transferred from untreated females to MNU‐treated or untreated pseudopregnant females. The results in the present study confirm and extend the previously proposed hypothesis that the direct effects of MNU on preimplantation embryos make a significant contribution to the induction of fetal malformations.
Isotretinoin (13‐cis‐retinoic acid) metabolism, cis‐trans isomerization, glucuronidation, and transfer to the mouse embryo: Consequences for teratogenicity
Authors: Kraft J. Creech , Eckhoff Chr. , Kochhar D. M. , Bochert G. , Chahoud I. , Nau H.
Published: February 2006

It has been reported that fractionated doses of 13‐cis‐retinoic acid are disproportionately more embryotoxic in pregnant mice than is the same dose given in a single bolus. Here, we examined limited pharmacokinetic profiles of a single (100 mg/kg dose given to NMRI mice on day 11 of gestation) versus multiple (3 × 100 mg/kg, 4 h apart) doses in an effort to assess the relative contribution to teratogenicity made by the drug and/or its metabolites. The major plasma metabolite of 13‐cis‐retinoic acid in the mouse was 13‐cis‐retinoyl‐β‐glucuronide, followed by the 4‐oxo metabolites and all‐trans‐retinoic acid. Transfer to the mouse embryo was very efficient for all‐trans‐retinoic acid, whereas, it was tenfold less efficient for 13‐cis‐retinoic acid and 100‐fold less efficient for 13‐cis‐retinoyl‐β‐glucuronide. The isomer all‐trans‐retinoic acid was found in the placenta at concentrations two‐ to three‐fold higher than in the plasma, suggesting placental accumulation as well as placental cis/trans isomerization. Since 13‐cis‐retinoyl‐β‐glucuronide and 13‐cis‐ and all‐trans‐retinoic acid were detected in the embryo after this multiple dosing schedule, any of the three or their combinations may have been involved in the induction of malformations, but all‐trans‐retinoic acid, a well‐known potent teratogen detected at concentrations of between 590 and 80 ng/g for 10 critical hours during gestation, could have been the major component.
A genotoxicological study of hexachlorobenzene and pentachloroanisole
Authors: Siekel Peter , Chalupa Ivan , Beňo Jozef , Blaško Milan , Novotný Jozef , Burian Ján
Published: February 2006

The potential mutagenic activity of hexachlorobenzene (HCB) and pentachloroanisole (PCA) was investigated. No genotoxicity after application on Salmonella typhimurium (Ames test), Escherichia coli, and human peripheral blood lymphocytes in vitro was observed.
Cytogenetic analysis of peripheral blood lymphocytes in workers occupationally exposed to polychlorinated biphenyls
Authors: Kalina Ivan , Šrám Radim J. , Konečná Helena , Ondruššeková Anna
Published: February 2006

The ability of polychlorinated biphenyls (PCBs) to induce chromosome aberrations and sister chromatid exchanges (SCE) in peripheral lymphocytes was studied in a group of workers occupationally exposed to PCBs during the production of the Czechoslovak PCB products Delor 103 and Delor 106. The effect of PCB exposure was compared between an exposed group (N = 32, 3.25 ± 0.34% aberrant cells, AB.C.), control group 1(N = 20, 1.30 ± 0.29% AB.C.), and control group 2 (N = 20, 1.60 ± 0.31% AB.C.). The length of PCB exposure over 10 yr increased the frequency of AB.C. in a group exposed for 11–15 yr to 3.40% (N = 5) and in a group exposed for 16–25 yr to 5.85% (N = 7) vs. an increase of 1.60% AB.C. in group C2 and of SCE to 12.6 ± 0.9/cell vs. 6.9 ± 0.7 SCE/cell in C2. The clastogenic activity observed in this group may be the result of a high PCB concentration in blood plasma (320 ± 190 μg PCB/1), and it is probably related to its solubility in adipose tissue, when it may act as another mutagen and carcinogen biotransformation inducer.
Quantitation and immunohistochemical localization of DNA adducts in rat embryos and associated yolk sac membranes exposed in vitro to N‐acetoxy‐2‐acetylaminofluorene (N‐Ac‐AAF)
Authors: Mirkes Philip E. , Little Sally A. , Beland Frederick A. , Huitfeldt Henrik S. , Poirier Miriam C.
Published: February 2006

Specific antibodies and radioimmunoassay (RIA) were used to measure the levels of acetylated and deacetylated C‐8 substituted deoxyguanosine adducts in day 11 rat embryos and their associated yolk sacs after exposure of whole rat conceptuses in vitro to the teratogen N‐acetoxy‐2‐acetylaminofluorene (N‐Ac‐AAF). The deacetylated adduct predominates in both the embryo and the associated yolk sac, and a dose response for adduct formation was observed when adducts were quantitated by RIA. Immunohistochemical localization of the deacetylated adducts revealed that adducts were confined to the nuclei in all tissues examined and that the abundance of adducts varied within and between tissues. Our initial findings indicate that specific DNA adduct antibodies may be useful in the study of teratogenesis induced by a wide variety of agents that modify DNA.
DNA strand breaks induced in cultured human and rodent cells by chlorohydroxyfuranones—mutagens isolated from drinking water
Authors: Chang Lina W. , Daniel F. Bernard , Deangelo Anthony B.
Published: February 2006

Chlorohydroxyfuranones, by‐products of chlorine disinfection and drinking water contaminants, are shown to produce DNA strand breaks in human and rodent cells. One chlorohydroxyfuranone, 3‐chloro‐4‐dichloromethyl‐5‐hydroxy‐2[5H]‐furanone (MX), a potent bacterial mutagen, induces 232 ± 89 DNA strand breaks.(cell‐μM)−1 in human CCRF‐CEM cells over a concentration range of 4.4 to 220 μM. This constitutes a DNA damage potency comparable to dimethylsulfate (DMS). By comparison, 3,4‐dichloro‐5‐hydroxy‐2[5H]‐furanone (MA), another chlorohydroxyfuranone which is approximately four orders of magnitude less mutagenic than MX in Salmonella typhimurium strain TA100 is only about tenfold less potent as an inducer of DNA strand breaks in these cells, i.e., 18.2 ± 3.1 strand breaks·(cell‐μM)±1. The DNA strand‐breaking potential of MX is inactivated by prior incubation with a rat liver S9 homogenate. In addition, both chlorohydroxyfuranones are ineffective at producing DNA strand breaks in primary rate hepatocytes (PRH) at concentrations below those which produce cytotoxicity as assessed by release of the cellular enzyme lactate dehydrogenase (LDH). Prior treatment of the PRH with μM diethyl maleate, a glutathione‐depleting agent, did not enhance the cytotoxicity nor the DNA strand‐breaking potential of either chlorohydroxyfuranone. This could indicate that glutathione‐glutathione‐S‐transferase is not an important mechanism for the detoxification of these compounds in PRH.
Heat shock proteins in human and mouse embryonic cells after exposure to heat shock or teratogenic agents
Authors: Honda Ken‐Ichi , Hatayama Takumi , Takahashi Ken‐Ichi , Yukioka Munehiko
Published: February 2006

In human chorionic villus tissue at the 10–17th week of a normal pregnancy, heat shock proteins (hsp70, hsp73, hsp85, and hsp105) were induced in vitro by a heat shock or by exposure to sodium arsenite or cadmium chloride. In dispersed cells of the whole mouse embryo on the 11th day of development, heat shock proteins (hsp73 and hsp105) were induced by a heat shock or by exposure to sodium arsenite, but not by exposure to cadmium chloride. After a maternal hyperthermia or an intraperitoneal injection of sodium arsenite or cadmium chloride into a pregnant mouse, heat shock proteins accumulated in the embryo on the 9th day of development, especially in the neuroepithelial tissue. The significance of heat shock proteins in the embryo is discussed. © 1992 Wiley‐Liss, Inc.
Dose response study of N‐nitrosodiethanolamine initiation of rat hepatocarcinogenesis
Authors: Ogawa Kumiko , Hasegawa Ryohei , Wada Shigetsugu , Yamaguchi Shuji , Ito Nobuyuki
Published: February 2006

Initiating activity of N‐nitrosodiethanolamine (NDELA) for rat liver carcinogenesis was investigated using an 8‐weeks bioassay system. Male F344 rats were initially treated with a single intraperitoneal injection of NDELA at one of five dose levels: 1,600, 800, 400, 200, or 100 mg/kg. Two weeks later, the rats were placed on 0.02% 2‐acetylaminofluorene (2‐AAF) or 0.05% phenobarbital (PB) containing diet for 6 weeks. All animals were subjected to 2/3 partial hepatectomy 4 weeks after the NDELA treatment, and killed at the end of the eighth week. NDELA itself exerted low toxicity in terms of body weight gain. Clear dose‐dependent initiating activity of NDELA was observed in terms of development of glutathione S‐transferase placental form (GST‐P) positive liver cell foci, this being more apparent with PB promotion than with 2‐AAF where the enhancing regimen itself caused multiple lesion development. Initiating potential of NDELA, however, was much lower than that observed for diethylnitrosamine in our previous work. © 1992 Wiley‐Liss, Inc.
Hyperploid cells in the limb buds of rats and 5‐azacytidine‐induced digital deformities
Authors: Kurishita Akihiro , Ihara Toshio
Published: February 2006

To clarify the mechanism underlying the digital teratogenesis of 5‐azacytidine (5‐AC), the DNA contents of mesenchymal cells were examined in the limb buds of the rat by microspectrophotometry. 5‐AC induced hyperploid cells: 2.4% at 18 h after injection and 3.2% at 24 h. No hyperploid cells were noted 30 h after the treatment. Because posttreatment caffeine suppressed 5‐AC‐induced digital defects, the actions of caffeine on 5‐AC‐induced hyperploid cells were further studied; no hyperploid cells were detected at any sampling point. Caffeine suppressed hyperploid cells as well as digital defects. These results suggest that the causative factors of digital defects by 5‐AC may involve hyperploid cells. However, in that there were too few hyperploid cells to cause the defects, further studies are required to clarify the nature of the action of 5‐AC. © 1992 Wiley‐Liss, Inc.
Ontogeny of peroxidase activity in epithelium and eosinophils of the mouse uterus
Authors: Newbold Retha R. , Jellinck Peter H. , Metzler Manfred , McLachlan John A.
Published: February 2006

Outbred CD‐1 mice treated for 1 or 4 days with 1 mg/kg of diethylstilbestrol (DES) at various ages after birth were examined for histochemical localization of peroxidase in the uterine epithelium. Peroxidase activity in uterine extracts was also measured by a radiometric assay and the conversion of [3H]DES to [3H]Z,Z‐dienestrol (Z,Z‐DIES). While no peroxidase activity was detected by a histochemical method in uterine epithelium from untreated 5‐day old mice, the enzyme was apparent in mice treated for 4 days with DES; uterine eosinophils were absent at this age. By day 9, DES‐induced staining for peroxidase in uterine epithelial cells and the number of uterine eosinophils had increased significantly. In addition, at this age, the biochemical assays for uterine peroxidase were sensitive enough to show that DES is converted to Z,Z‐DIES and that [3H]estradiol gives rise to 3H2O and water‐soluble radioactive metabolites. The peroxidase response to DES, determined by both histochemical and biochemical methods, increased with the age of the immature mice. These data indicate that the neonatal uterus, although deficient in eosinophils, demonstrates a peroxidase response to estrogen and that this response is localized primarily in the luminal epithelium. The role of this DES‐induced peroxidase activity in converting DES to activated metabolites that may cause cell damage is discussed. © 1992 Wiley‐Liss, Inc.
Transplacental exposure to tobacco smoke in human‐adduct formation in placenta and umbilical cord blood vessels
Authors: Hansen Claus , Sørensen Lene D. , Asmussen Inger , Autrup Herman
Published: February 2006

Smokers are exposed to a large number of genotoxic compounds that react with DNA to form covalently bound carcinogen—DNA adducts after metabolic conversion to their biological active form. Using the P32‐postlabeling techniques, tobacco smoke related carcinogen—DNA adducts have been demonstrated in DNA isolated from human placenta and umbilical cord vein and artery obtained from 11 nonsmoking and 8 smoking normal healthy women and foetuses. The adduct level was significantly higher in tissues from smokers than from nonsmokers (P = 0.021), when all tissues were combined. Furthermore, the total adduct level was higher in maternal tissue than the level in fetal tissues (P = 0.030). The adduct level in umbilical cord vein DNA was significantly lower than in placenta, and marginally lower than in umbilical cord artery from the same donor. This suggests that the foetus can metabolise some of the genotoxic compounds found in tobacco smoke to DNA‐binding metabolites. The presence of DNA adducts in foetal tissues is indicative of potential genomic damage, that may result in an increased risk for the development of serious diseases, like cancer in childhood or later during the life span of the individual. © 1992 Wiley‐Liss, Inc.
Strategy of research for cancer—chemoprevention
Authors: Ito Nobuyuki , Imaida Katsumi
Published: February 2006

It has been reported that environmental chemicals are important factors in terms of both development and prevention of human cancer. For the latter, detection of early stages is an essential first step followed by clinical trials for surveying populations at risk. Thus a great deal of attention has been focused on these areas. However, investigations of possibilities for active prevention of cancer development itself form another major project. Chemoprevention of carcinogenesis, which means prevention of carcinogenesis by exogenous chemical compounds, has been investigated extensively in a variety of organs in animal models. Usually attention is concentrated on only one organ. However, antioxidants, such as BHA, exert very different effects on different organs, suggesting the necessity of whole body approaches to the question of chemoprevention. Furthermore, the mechanisms of chemoprevention, including the step of carcinogenesis, i.e., initiation, promotion, progression or whole carcinogenesis steps, in which exogenous compounds exert their protective effects, should be considered.

A medium‐term bioassay system and a multi‐organ carcinogenesis system, which can be used for investigation of potential for cancer chemoprevention, have been developed in our laboratory. Dose dependent inhibitory effects were established for both BHA and α‐tocopherol in the medium‐term bioassay system, and inhibition of small intestinal carcinogenesis by catechins in green tea has also been investigated in our multi‐organ carcinogenesis protocol. It is extremely important for prevention of human cancer that we find new candidates for chemopreventive agents using animal studies.

This paper reviews published reports on chemoprevention, taking into account effective stage, and proposes suitable experimental animal models for future investigations in this increasingly important area. © 1992 Wiley‐Liss, Inc.
Tumor formation and sister chromatid exchange induction by ethyl carbamate: Relationships among non‐pregnant murine females, gravid dams, and transplacentally exposed offspring
Authors: Neeper‐Bradley T. L. , Conner Mary K.
Published: February 2006

Sister‐chromatid exchange (SCE) induction and cell cycle kinetics alterations by ethyl carbamate in bone marrow of non‐gravid murine Swiss Webster, ICR/Jcl, and C57Bl/6J dams were evaluated, and data from non‐gravid females were compared with those previously reported for pregnant dams of the same strains. In addition, lung adenoma induction by ethyl carbamate in gravid Swiss Webster dams, their offspring, and in non‐pregnant Swiss Webster females was also determined. Relative cytogenetic and tumor responses in non‐gravid and gravid Swiss Webster females and their offspring were compared. In contrast to the increased sensitivity reported for gravid Swiss Webster dams versus ICR/Jcl and C57Bl/6J dams, SCE responses to 1.1, 2.2, or 3.3 mmol/kg of ethyl carbamate in non‐gravid females were approximately equivalent among strains. In Swiss Webster and C57Bl/6J (but not ICR/Jcl) strains, SCE responses in non‐gravid females at 2.2 and 3.3 were significantly lower than those of their pregnant counterparts. Tumor induction by 3.3 mmol/kg ethyl carbamate paralleled relative SCE induction with Swiss Webster dams, demonstrating a 5‐fold increase in the number of tumors relative to their offspring and a 4‐fold enhancement of tumor induction relative to their non‐pregnant counterparts. © 1992 Wiley‐Liss, Inc.
Effects of various bile acids and their sodium salts on development of pepsinogen‐altered pyloric glands in rats
Authors: Yoshida Yasunori , Tatematsu Masae , Takaba Katsumi , Shichino Yutaka , Ito Nobuyuki
Published: February 2006

Effects of dietary bile acids and their sodium salts on the development of pepsinogen‐altered pyloric glands (PAPG) were examined in male WKY/N Crj rats initially given a single dose of 160 mg/kg body weight of N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) by gastric intubation. From week 3 the animals were administered basal diet containing 0.5% supplements of cholic acid (CA), deoxycholic acid (DCA), chenodeoxycholic acid (CDCA) or their sodium salts (Na‐C, Na‐DC and Na‐CDC), or 5% ascorbic acid (ASA) or its salt (Na‐AS) for 18 weeks. The concentration of DCA and Na‐DC was reduced to 0.3% from week 12. At week 20, animals were killed and the numbers of immunohistochemically‐demonstrated PAPG were determined. Values were significantly higher with Na‐C and Na‐CDC than with the corresponding parent acids, and in the Na‐C case PAPG development was greater than with MNNG alone. In addition, Na‐CDC itself induced the numbers of PAPG significantly. These results suggest that bile salts are possible intrinsic promoters of gastric carcinogenesis. They were without effect, however, on forestomach lesions. © 1992 Wiley‐Liss, Inc.
The modulatory effects of tryptamine and tyramine on the S9‐mediated mutagenesis of IQ and MelQ in Salmonella strain TA98
Authors: Abu‐Shakra Amal
Published: February 2006

The S9‐mediated mutagenesis of IQ and MeIQ in Salmonella strain TA98 was modulated by introduction to the assay of tryptamine or tyramine. Both biogenic amines inhibited or enhanced the mutagenic response as a function of amine concentration, strain of rat used as the S9 source, and the IQ‐type mutagen tested. Enhancement of IQ mutagenesis by tryptamine (10–80 μM) was observed in the presence of S9 preparations derived from Aroclor 1254‐pretreated Fischer rats; the enhancing effect ceased at tryptamine concentrations > 160 μM. When Sprague‐Dawley‐S9 or Wistar‐S9 were used for activation, the enhancement of IQ mutagenesis by tryptamine shifted to inhibition at tryptamine concentrations >40 μM, with Sprague‐Dawley‐S9, and > 20μM, with Wistar‐S9. By contrast, MeIQ‐mutagenesis was enhanced by tryptamine (10 – 160μM), regardless of the rat strain used as S9 source. Tyramine was a weaker enhancer of MeIQ mutagenesis than was tryptamine and, unlike tryptamine, its inhibitory effects on IQ mutagenesis were observed only with Wistar‐S9. Tryptamine (10–80 μM) inhibited cytochromes P450IA1 and P450IA2 activities, monitored by the O‐deethylation of ethoxyresorufin and Glu‐P‐1 mutagenesis in TA98, respectively. These data suggest that the effects of biogenic amines on IQ and MeIQ bioactivation are complex. Furthermore, this study demonstrates that tryptamine and tyramine act both as enhancers (comutagens) and as inhibitors (antimutagens) of IQ and MeIQ mutagenesis, depending on the testing conditions. © 1992 Wiley‐Liss, Inc.
Methotrexate increases valproic acid‐induced developmental toxicity, in particular neural tube defects in mice
Authors: Elmazar M. M. A. , Nau H.
Published: February 2006

The hypothesis that valproic acid‐induced dysmorphogenesis may be due to an interference of this drug with folate metabolic pathways was further investigated by a study of a possible interaction of valproic acid (VPA) and the established folate antagonist methotrexate (MTX). The dihydrofolate reductase inhibitor MTX (1.25 and 2.5 mg/kg, i. p.) was injected 15 min prior to VPA (300 and 400 mg/kg, s. c.) in day 8 pregnant NMRI mice. Fetuses were examined for exencephaly, resorption, and fetal weight retardation on day 18 of gestation. MTX produced no exencephaly or reduction in fetal weight, and the 2.5‐mg/kg dose caused 56% resorption. Higher doses (5–20 mg/kg) produced embryolethality and fetal weight retardation, but no exencephaly. VPA (300 and 400 mg/kg) administration resulted in 3.4% and 12.6% exencephaly and 9% and 19% resorptions, respectively. Coadministration of MTX with VPA significantly increased VPA‐induced resorption and exencephaly rates as well as fetal weight retardation. Exencephaly induced by VPA 400 mg/kg was increased to 29.5% and 24.1% (P < 0.01 and P < 0.05) when given with 1.25 and 2.5 mg/kg MTX, respectively. MTX (2.5 mg/kg i.p.) did not alter transplacental VPA (400 mg/kg, s.c.) pharmacokinetics. These results support the view that VPA‐induced teratogenesis may be mediated by interaction with folate metabolism. © 1992 Wiley‐Liss, Inc.
Teratological study of stobadin after single and repeated administration in rats
Authors: Ujházy Eduard , Balonová Tatiana , Vargová Tamara , Janšák Jozef , Derková L'Ubica
Published: February 2006

The toxic developmental potential of the anti‐arrhythmic drug stobadin was assessed after single intravenous or repeated oral doses to pregnant rats. Stobadin was studied in the form of dihydrochloride (DH 1011) at doses of 2 and 6 mg/kg, given in single intravenous injections on days 3,6,9, or 12 of gestation. Immediately after injection of the 6‐mg/kg dose of DH 1011 to pregnant rats, saccade abdominal respiration, tremor of hindlimbs, and sedative behaviour were observed on each day of medication. No deaths of females occurred in either the control or experimental groups. Slight foetal toxicity was manifested by significantly decreased foetal weight only after treatment on day 3 of gestation at 6 mg/kg and by significantly increased incidence of delayed ossification of the parietal and supraoccipital bone also at 6 mg/kg DH 1011 given on day 12 of gestation. The effect of repeated oral treatment in the form of dipalmitate salt (DP 1031) was studied in doses of 5, 15, and 45 mg/kg from days 2–15 of gestation. Oral exposure to 45 mg/kg DP 1031 resulted in significant reduction of maternal body weight gain and in embryofoetal toxicity, namely, increased preimplantation foetal loss, anomalies of sternebrae, and, after 15 and 45 mg/kg DP 1031, significantly decreased foetal weight and smaller litter size. The relevance of the two routes of stobadin administration for risk extrapolation is discussed. © 1992 Wiley‐Liss, Inc.
Analysis of cytogenetic damage induced in CHO cells by the pyrethroid insecticide fenvalerate
Authors: Caballo Covadonga , Herrera Angustias , Barrueco Carmen , Santa‐María Ana , Sanz Félix , de la Peña Eduardo
Published: February 2006

A synthetic pyrethroid insecticide, fenvalerate, was tested for its ability to induce chromosome aberrations (CA) and sister chromatid exchanges (SCE) in CHO cells. Fenvalerate was assayed both in the presence and in the absence of a rat liver activation system (S9‐mix).

Our results indicate that fenvalerate in the presence of S9‐mix is able significantly to increase the frequency of CA, while in the SCE test this increase occurred both in the presence and in the absence of S9‐mix.

In addition, fenvalerate affected the cell cycle, causing a decrease in the mitotic index (MI) and in the proliferative rate index (PRI). © 1992 Wiley‐Liss, Inc.
Analysis of carcinogenic activity of some pesticides in a medium‐term liver bioassay in the rat
Authors: Hakoi K. , Cabral R. , Hoshiya T. , Hasegawa R. , Shirai T. , Ito N.
Published: February 2006

Eight pesticides were tested in a medium‐term bioassay based upon the induction of preneoplastic lesions in the liver. Rats were initially given diethylnitrosamine intraperitoneally at a dose of 200 mg/kg body weight and 2 weeks later were treated with the pesticides for 6 weeks and then killed; all rats had a partial hepatectomy at week 3. Hepatocarcinogenic potential was assessed by comparing the number and area of glutathione S‐transferase placental form positive foci in the liver with those of controls given diethylnitrosamine (DEN) alone. Positive results were seen with p,p‐DDT and Triadimefon. Permethrin (mixture of 39% cis form and 61% trans form) showed borderline results. Permethrin (25/75), Deltamethrin, Cypermethrin (52/48), while Trimorphamide and Propineb gave negative results. Our findings provide experimental evidence to indicate that compounds active in this assay have a potential for liver carcinogenicity in rodents. © 1992 Wiley‐Liss, Inc.
Comparative joint actions of semicarbazide and thiosemicarbazide on induction of malformations and osteolathyrism in mixtures with benzoic hydrazide
Authors: Dawson Douglas A.
Published: February 2006

A developed mixture testing protocol, evaluating malformation of Xenopus embryos, was used to examine the joint actions of semicarbazide (SC) and thiosemicarbazide (TSC) with benzoic hydrazide (BZH). These compounds were selected to evaluate the effect of a substitution of sulfur for oxygen on osteolathyrism induced in Xenopus embryos. Binary combinations of SC with BZH and TSC with BZH were tested using three mixture ratios for each combination. Each compound was simultaneously tested alone in 96 h static‐renewal tests, starting with late‐blastula stage embryos. Toxic unit analysis, evaluating induction of malformations in general and osteolathyrism specifically, indicated the joint action for each combination was concentration addition. The results indicate that the three chemicals are similar and non‐interactive and are likely to induce osteolathyrism by the same primary mechanism of action. ©1993 Wiley‐Liss, Inc.
Sodium butyrate differentially modulates plasminogen activator inhibitor type‐1, urokinase plasminogen activator, and its receptor in a human colon carcinoma cell
Authors: Reeder Jennifer A. , Dickinson Joanne L. , Chenevix‐Trench Georgia , Antalis Toni M.
Published: February 2006

Human colonic epithelium is exposed to varying levels of sodium butyrate, which is derived from the bacterial fermentation of dietary carbohydrate. Sodium butyrate has several effects on colonic tumor cells in vitro, including arrest of cell growth and differentiation. In the present study we have found that, in addition to a reduction in cellular proliferation, sodium butyrate induces the transient expression of plasminogen activator inhibitor type‐1 (PAI‐1) in the LIM 2405 human colonic tumor cell. Approximately 40% of the PAI‐1 secreted is biologically active as judged by the formation of higher molecular weight, SDS‐resistant complexes with urokinase plasminogen activator (uPA). The enhanced PAI‐1 biosynthesis was accompanied by an increase in PAI‐1 mRNA levels. During the same time period, the amount of secreted uPA remained relatively constant, but the level of cell associated uPA decreased slowly and was accompanied by a decrease in uPA mRNA levels. The uPA receptor is synthesized constitutively by these cells, and was down‐regulated at both the protein and mRNA levels in response to sodium butyrate. The results demonstrate that sodium butyrate can alter the balance of components of the plasminogen activator system in a manner which favours net decreased plasminogen activator activity and suggests a role for sodium butyrate in the regulation of extracellular proteolysis. ©1993 Wiley‐Liss, Inc.
Predicting rodent carcinogenicity of halogenated hydrocarbons by in vivo biochemical parameters
Authors: Kitchin Kirk T. , Brown Janice L. , Kulkarni Arun P.
Published: February 2006

Forty halogenated hydrocarbons of known rodent carcinogenicity (24 carcinogens, 16 noncarcinogens), including many promoters of carcinogenesis, nongenotoxic carcinogens, and hepatocarcinogens, were selected for study. The chemicals were administered by gavage in two dose levels to female Sprague‐Dawley rats. The effects of these 40 chemicals on four biochemical assays [hepatic DNA damage by alkaline elution (DD), hepatic ornithine decarboxylase activity (ODC), serum alanine aminotransferase activity (ALT), and hepatic cytochrome P‐450 content (P450)] were determined.

Composite predictive parameters are defined as follows: CP = [ODC and P450], CT = [ALT and ODC], and TS = [DD or CP or CT]. The operational characteristics of TS for predicting rodent cancer were sensitivity 58%, specificity 81%, positive predictivity 82%, negative predictivity 57%, and concordance 68%. The concordance for the Ames test (45%) and structural alerts (SA; 46%) was much lower. TS also outperformed the Ames test and SA in producing fewer false positives (the specificity of TS was 81% vs. only 63% for the h e s test and 57% for SA). For predicting the carcinogenicity of the most difficult halogenated hydrocarbons (Ames and SA negative chemicals), TS was capable of success‐ fully predicting the carcinogenicity of 8 (carbon tetrachloride, chloroform, α‐hexachloro‐cyclohexane, kepone, mirex, monuron, p,p′‐DDE, and 2,4,6‐trichloropheno1) out of 16 of these non‐DNA‐reactive halogenated hydrocarbon carcinogens. All 8 of these halogenated hydrocarbons were positive in either CP or CT. This evidence shows that nongenotoxic carcinogenesis is best predicted by nongenotoxic parameters such as CP or CT (components of the predictor TS). ©1993 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the publi domain in the United States of America.
Perspective on the usefulness of the mouse lymphoma assay as an indicator of a genotoxic carcinogen: Ten compounds which are positive in the mouse lymphoma assay but are not genotoxic carcinogens
Authors: Caldwell John
Published: February 2006

The mouse lymphoma assay is commonly included in batteries of tests for the mutagenic and carcinogenic potential of chemicals. Unlike other bacterial and mammalian cell tests, it has an unacceptably high incidence of false positive results. This paper reviews data on ten chemicals, all of which are positive in the mouse lymphoma assay but negative in all other genotoxicity tests. Three are non‐genotoxic rodent carcinogens acting through a variety of secondary mechanisms, while seven are not carcinogenic. It is concluded that a positive mouse lymphoma assay alone cannot be a barrier to the human use of drugs and other chemicals. ©1993 Wiley‐Liss, Inc.
Modification of antigen expression in human and hamster pancreatic cancer cell lines induced by sodium butyrate
Authors: Corra Stefano , Kazakoff Katherine , Mogaki Masatoshi , Cano Martin , Pour Parviz M.
Published: February 2006

The effects of sodium butyrate (NaB) on the growth, morphology, and expression of blood group A, Lewisa, and CA 19‐9 antigen in the hamster pancreatic cancer cell lines, PC‐1 (well differentiated) and PC‐1.0 (poorly differentiated), and of blood group A, DU‐PAN‐2, and CA 19‐9 antigens in four human pancreatic cancer cell lines, HPAF and CD11 (well differentiated) and CD18 and PANC‐1 (poorly differentiated), were examined. NaB inhibited the growth of all cell lines and induced cell enlargement, an increase in secretory material, microfilaments, and pseudopodia. NaB stimulated the production of blood group A antigen in PC‐1.0 cells dose dependently, but no change in the expression of this antigen was observed in the human cell lines. However, NaB treatment increased the presence of cells positive for CA 19‐9 in PANC‐1 but not in the remaining cell lines, none of which reacted with the anti‐CA 19‐9 antibody before or after NaB treatment. Untreated PANC‐1 cells did not produce either blood group A or DU‐PAN‐2 antigen, but expressed these antigens after NaB treatment in a dose‐dependent manner. The results suggest that NaB stimulates the differentiation of the hamster and human pancreatic cancer cell lines and increases or induces the expression of some tumor‐associated antigens. ©1993 Wiley‐Liss, Inc.
Sequencing analysis of Ha‐, Ki‐, and N‐ras genes in rat urinary bladder tumors induced by N‐[4‐(5‐nitro‐2‐furyl)‐2‐thiazolyl]formamide (FANFT) and sodium saccharin
Authors: Masui T. , Mann A. M. , Borgeson C. D. , Garland E. M. , Okamura T. , Fujii H. , Pelling J. C. , Cohen S. M.
Published: February 2006

Male F344 rats were fed N[4‐(5‐nitro‐2‐furyl)‐2‐thiazolyl]formamide (FANFT) for up to 4 wk, then given the basal diet with or without 5% sodium saccharin for up to 100 wk. In a previous study, we demonstrated point mutations in codons 12 and 61 of Ha‐ras gene among eleven transitional cell carcinomas (TCC), one undifferentiated carcinoma, and two sarcomas of the urinary bladder (Mol Carcinogen 3:210–215, 1990). In this study, Ha‐ras, Ki‐ras, and N‐ras sequences were examined by polymerase chain reaction (PCR) and direct DNA sequencing. The results confirm the point mutation in codon 61 (CAA to CGA in 5 TCCs and to CTA in one TCC) of the Ha‐ras gene. Mutation at codon 12 was not confirmed. No mutation was found in the Ki‐ras gene. Sequences of the N‐ras gene exons 1 and 2 were determined, and no mutations was detected. These results suggest the involvement of activated Ha‐ras gene, but not Ki‐N or N‐ras gene, in rat urinary bladder carcinogenesis induced by FANFT. Subsequent sodium saccharin administration did not affect the changes in Ha‐ras gene. ©1993 Wiley‐Liss, Inc.
Cytosine attack by free radicals arising from bromotrichloromethane in the presence of benzoyl peroxide catalyst: A mass spectrometric study
Authors: Castro G. D. , Castro J. A.
Published: February 2006

We and others previously reported that CCl4 reactive metabolites are able to covalently bind to liver DNA either in vivo or in vitro. However, no demonstration of the structure of resulting adducts is available in literature. That information would be of relevance, for CCl4 exhibits null or contradictory mutagenic properties and is currently considered a non‐genotoxic carcinogen.

In the present study we report the nature of the reaction products formed when the putative CCl4 metabolites, ·CCl3 and CCl3O2· attack cytosine in a purely chemical system where they were generated from CCl3Br in a benzoyl peroxide catalyzed reaction.

Reaction products formed and identified were a) under nitrogen (·CCl3 present)—5‐bromo cytosine and cytosine‐5‐carboxylic acid; b) under air (CCl3O2· present)—5‐bromo cytosine, 5‐chloro cytosine, 5‐hydroxy cytosine, 6‐hydroxy cytosine (tentative), chloro hydroxy uracil, 5,6‐dihydroxy uracil, and chloro trichloromethyl cytosine.

Results from present experiments suggest that if these reaction products were also produced in vivo during either CCl4 or CCl3Br poisoning and they were not repaired in due time prior to replication, they would lead to mutagenic events. Studies directed to obtain evidence for their in vivo formation are in course in our laboratory. ©1993 Wiley‐Liss, Inc.
Comparative kinetic studies on aflatoxin B1 binding to pulmonary and hepatic DNA of rat and hamster receiving the carcinogen intratracheally
Authors: Biswas Gopa , Raj Hanumantharao G. , Allameh Amir , Saxena Manju , Srivastava Narender , Mukerji Krishna G.
Published: February 2006

Several epidemiological studies have discussed the outcome of inhalation of airborne aflatoxins by humans. Metabolism of aflatoxin B1 (AFB1) by lung parenchyma leading to DNA binding is reported here. The tissue distribution pattern of [3H]AFB1 radioactivity revealed the lungs to be the second most important organ after the liver to retain a considerable amount of the radioactivity (66%). The lung indicated a selective activation of AFB1 as it showed only 7.7% binding of [3H]AFB1 to pulmonary DNA. Rats and hamsters were dosed with [3H]AFB1 (2 μCi containing 40 μg AFB1/100 g body wt.) intratracheally (i.t.) and sacrificed at different intervals after toxin treatment. Peak binding occurred at 0.5, 1, and 2 h in case of hamster lung, rat lung, and alveolar macrophages of both the species, respectively. At the end of 24 h, the relative AFB1‐DNA binding (percentage of peak binding) in hamster lung was 72% while that in rat was 24%. The relative binding in rat lung alveolar macrophages (AMs) was generally higher than that of the hamster. AFB1 binding to hepatic DNA of both the species approached the peak at 1 h after the toxin administration i.t. Under these conditions, binding of AFB1 (or its metabolites translocated to liver) to hepatic DNA of both the species progressively diminished with time in contrast to lung, as revealed by the relative binding values at 12 h for rat and hamster lung, which were 48 and 67%, respectively, while for the rat and hamster liver they were 28 and 24%, respectively. Binding of i.t. administered [3H]AFB1 to rat liver DNA is only marginally higher than that observed with hamster liver, in contrast to the wide difference observed in animals receiving AFB1 intraperitoneally. These results highlight the persistence of AFB1 binding to pulmonary DNA, and the extent of translocated AFB1 binding to hepatic DNA presents an interesting difference from that observed when the toxin was administered through a gastrointestinal route. It is worth concluding that AMs unlike many other xenobiotics, possess specific mixed function oxidase activity to epoxidize AFB1. ©1993 Wiley‐Liss, Inc.
DNA alkyation and mutagenicity of related hydroxypropylating and methylating agents in V79 cells
Authors: Lawson Terence , Gannett Peter
Published: February 2006

N‐Nitrosobis (2‐hydroxypropyl) amine (BHP) and N‐nitrosobis (2‐oxopropyl) amine (BOP) require metabolism to be carcinogenic and mutagenic. This metabolism produces hydroxypropylating and methylating alkylating species. To measure the effects of these species, we compared the action of direct‐acting model compounds that are hydroxypropylating or methylating agents with those of BHP and BOP. Mutagenicity in V79 cells and the alkylation of V79 cell DNA were measured. The model compounds were ethyl‐N‐nitroso (2‐oxopropyl) carbamate (NOPC), a methylating agent, and its 2‐hydroxypropyl congener (NHPC), a hydroxypropylating agent. BHP and BOP were metabolized by hepatocytes from male Syrian hamsters. At the highest dose (2 mM) BOP produced 12 times more mutants than BHP but only 2.5 times more O6methylguanine (O6MeG) than BHP. When a pancreas duct homogenate was used, 87 (BOP) and six (BHP) mutants/106 survivors were measured. When hepatocytes (not a homogenate) were used to metabolize BOP, 351 μmol O6MeG/mol guanine (G) and 39 μmol O6 (2‐hydroxypropyl) G (O6HpG)/mole G were found in V79 DNA. When a pancreas duct homogenate was used BHP produced O6HpG (65 μmol/mol G) and BOP O6MeG (20 μmol/mol G). NOPC produced five times more mutants than NHPC, over the range of doses. At the highest dose (10 μM) it produced less (70%) O6alkylG than NHPC. These data show that methylation was a more mutagenic lesion than hydroxypropylation. There was no evidence of a correlation between mutagenicity and the formation of O6alkylG. ©1993 Wiley‐Liss, Inc.
Stability of microsomal monooxygenases in murine liver S9 fractions derived from phenobarbital and β‐naphthoflavone induced animals under various long‐term conditions of storage
Authors: Bauer Carlo , Corsi Claudio , Paolini Moreno
Published: February 2006

The aim of this study was to define the long‐term stability of metabolizing enzymes in activating preparations for short‐term genotoxicity bioassays under various storage conditions. Expressions of cytochrome P450 content, NADPH‐cytochrome (P450) c‐re‐ductase activity, and of the several monooxygenases, such as aminopyrine N‐demethylase (class IIIA P450), p‐nitroanisole O‐demethylase (mixed), dinemorphan N‐demethylase (HB1), ethoxyresorufin O‐deethylase (IA1), ethoxycoumarin O‐deethylase (mixed), and pentoxyresorufin O‐dealkylase (IIB1), were examined in S9 fractions derived from Na‐phenobarbital (PB) plus β‐naphthoflavone (β‐NF) induced male and female mice, stored at −80°C, or lyophilized and stored at −20°C. Lipid peroxidation was also determined. Cytochrome P450 and the associated activities were decreased by 30–82% within 9 months of storage. The pattern and degree of relative stabilities were different for the various isoforms. The IA 1‐like activity, for example, was much more stable (˜49%loss) than IIB 1‐like activities (up to 82% loss). In general, lyophilized enzymes were less stable than directly frozen preparations. In addition, immediately after freeze‐drying (lyophilization), a marked decrease in activity of up to 35% was observed. On the contrary, demethylation of aminopyrine and p‐nitroanisole remains almost constant over 6 months storage at −196°C. The results obtained indicate that either fresh, daily made S9 fractions or, alternatively, fractions stored in liquid nitrogen (up to 6 months) are recommended for mutagenesis studies. © 1994 Wiley‐Liss, Inc.
Taxol and embryonic development in the chick
Authors: Scialli Anthony R. , Desesso John M. , Goeringer Gerald C.
Published: February 2006

Taxol, an inhibitor of microtubule disassembly, is currently under investigation in the therapy of several human cancers. The current investigation was undertaken to characterize potential taxol developmental toxicity in chicks. On one of days 1–4 of incubation, taxol was administered in dimethylsulfoxide (DMSO) or olive oil in a range of doses, the highest of which produced a high incidence of early embryo death. Production of gross structural malformations was sporadic and occurred in vehicle‐treated as well as taxol‐treated embryos. A more common manifestation of taxol toxicity was a syndrome of visceral abnormalities, including regression of the vitelline circulation, dilatation of the atria, and hemorrhage in the left side of the head and thorax, often with decreased eye pigmentation. Regardless of the day of treatment, this syndrome occurred at 4.5–5 days. To investigate the possibility that taxol induced its effect through disruption of angiogenesis in the vitelline circulation, filters soaked in taxol were applied to the margin of the germ disc. No inhibition of vessel development was demonstrated. We conclude that taxol decreases the viability of embryos and that this impairment of survival precludes the development of birth defects. Solvent toxicity is an important confounder in the investigation of taxol embryotoxicity. © 1994 Wiley‐Liss, Inc.
Induction of structural chromosome aberrations in human lymphocyte cultures and CHO cells by permethrin
Authors: Barrueco Carmen , Herrera Angustias , Caballo Covadonga , de la Peña Eduardo
Published: February 2006

The pyrethroid insecticide permethrin was tested for its ability to induce structural chromosome aberrations (CA) in human lymphocyte cultures and CHO cells, in order to confirm the clastogenic effect of itself and to compare the response of the two different cell types. Permethrin was tested in the range of 50–200 μg/ml in human lymphocyte cultures and in the range of 20–100 μg/ml in CHO cells. In both lymphocyte and CHO cultures, assays were performed in the absence and in the presence of a rat liver activation system (S9 mix). In the absence of S9 mix, two experiments with different duration of the treatment were carried out. Permethrin induced CA in both cultures when it was evaluated in the absence of a metabolic activation system. The activity of a given concentration of permethrin seemed to be decreased more by the reduction of the time of exposure than by the presence of S9 mix. Aberrations induced by permethrin were mainly chromosome‐type aberrations in both cultures. Thus, permethrin can be characterised as an S‐phase independent clastogenic agent. The response of both lymphocyte and CHO cultures was similar, indicating that both systems showed the same sensitivity for detecting the clastogenicity in vitro of permethrin. © 1994 Wiley‐Liss, Inc.