Search

Madder color (MC), a food coloring extracted from roots of Rubia tinctorum L. and used in Japan, proved to have carcinogenic potential on the rat kidney and liver. In addition, madder root is reported to induce DNA adducts in the kidney, liver and large intestine (Westendorf et al., 1998). MC is composed of some anthraquinones including lucidin-3-O-primeveroside (LuP) and alizarin (Alz). To clarify which component is responsible for carcinogenicity, a rat medium-term multi-organ carcinogenesis bioassay was performed, mainly focusing on the kidney, liver and large intestine. Male 6-week-old F344 rats receiving 5 different carcinogens were fed a diet containing either 0.008% or 0.04% of Alz or rubiadin (Rub), a metabolite of LuP, for 23 weeks. In the kidney, 0.04% Rub increased the incidences of atypical tubules and hyperplasias significantly (p These results indicate the kidney as a carcinogenic target of both Rub and Alz, the carcinogenic potential of the latter being weaker. Rub may also target liver and large intestine, suggesting that Rub plays a major role in MC-induced carcinogenicity.

Developmental hypothyroidism causes brain retardation due to impairment of neuronal migration and oligodendroglial myelination. Brominated flame retardants (BFRs), potential environmental pollutants to cause bioaccumulation, usually exert low or no toxicity in conventional toxicity studies, but some of them are known to induce mild hypothyroidism. To search for target genes responsible for possible brain retardation due to developmental exposure to BFRs, we performed a global gene expression profiling specific to the cerebral white matter of rat pups exposed to decebromodiphenyl ether (DBDE) during development. Dams were given DBDE at 10, 100, or 1000 ppm in diet during the period from gestation day 10 to postnatal day 21 (weaning). As a positive control for hypothyroidism, methimazole (MMI) at 200 ppm or propylthiouracil (PTU) at 3 or 12 ppm was given via drinking water. At weaning, bilateral cerebral white matter and corpus callosum (CC) were selectively microdissected from male pups and subjected to microarray analysis. As a result, 10% of genes showing altered expression by DBDE were identical to those induced by anti-thyroid agents (MMI and PTU) including glial cell differentiation, axon guidance, myelination, or cellular migration. Also, DBDE-alone induced expression alteration of genes related to similar functions as with anti-thyroid agents. At 11 weeks of age, offspring were subjected to brain morphometry regarding white matter components. As a result, as well as anti-thyroid agents, DBDE reduced the CC area and the density of CNPase-positive oligodendrocytes suggestive of reduced white matter development. Results thus suggest that glial development-related genes obtained here with DBDE may be linked to or independent of developmental hypothyroidism that is shown here for the first time with DBDE as white matter hypoplasia.

In order to assess the effect of cigarette smoke (CS) on metabolic enzymes, male hamsters and rats were exposed for two weeks to smoke produced in a Hamburg type II smoking machine. The livers were then used for Ames liquid incubation and western immunoblot assays. Mutagenic activities of seven heterocyclic amines (HCAs) in Salmonella typhimurium TA98 in the presence of rat or hamster liver S9 were elevated up to 3.7 times above controls (including sham smoke control). Enhancement of mutagenic activities of PhIP and aflatoxin B(1) was observed only in CS-exposed hamster, whereas no significant alteration of mutagenicity was observed with 2-aminofluorene, benzo[a]pyrene, and 3'-hydroxymethyl-N, N-dimethyl-4-aminoazobenzene in strain TA98 or with six N-nitrosodialkylamines in strain TA100. 7,8-Benzoflavone and/or furafylline considerably inhibited the mutagenic activation of IQ and Trp-P-1 in the presence of liver S9 from untreated hamsters and sham smoke- or CS-exposed hamsters and rats, indicating the predominant involvement of hamster cytochrome P450 (CYP) 1A enzymes in the metabolic activation of HCAs. In addition, the data suggest that CS-exposure may selectively induce hepatic CYP1A1/1A2 isoforms. Western immunoblot analyses of liver microsomes using anti-rat CYP antibodies revealed that CS-exposure increased the levels of hamster CYP1A2 (3.9-fold) and rat CYP1A2 (3.0-fold) and CYP1A1, without significant change in the levels of CYP2E1 and CYP2B and 3A isoforms in each species. The presently observed selective induction of HCA activation and CYP isozymes due to CS supports the idea that CS may contribute to enhancing effects on initiation by carcinogens which are metabolically activated by hepatic CYP1A1/1A2. In conjunction with results observed for smokers, the present findings indicate that the hamster is a good animal for studies with CS, and that cigarette smoking in combination with intake of heating protein-rich foods as a life style may markedly contribute to the human carcinogenesis by HCAs.

The detection of 1,N2-propanodeoxyguanosine adducts in the DNA of rodent and human tissues as endogenous lesions has raised important questions regarding the source of their formation and their roles in carcinogenesis. Both in vitro and in vivo studies have generated substantial evidence which supports the involvement of short- and long-chain enals derived from oxidized polyunsaturated fatty acids (PUFAs) in their formation. These studies show that: (1) the cyclic propano adducts are common products from reactions of enals with DNA bases; (2) they are formed specifically from linoleic acid (LA; omega-6) and docosahexaenoic acid (omega-3) under in vitro stimulated lipid peroxidation conditions; (3) the levels of propano adducts are dramatically increased in rat liver DNA upon depletion of glutathione; (4) the adduct levels are increased in the liver DNA of the CCl4-treated rats and the mutant strain of Long Evans rats which are genetically predisposed to increased lipid peroxidation; and (5) adduct levels are significantly higher in older rats than in newborn rats. These studies collectively demonstrate that tissue lipid peroxidation is a main endogenous pathway leading to propano adduction in DNA. The possible contribution from environmental sources, however, cannot be completely excluded. The mutagenicity of enals and the mutations observed in site-specific mutagenesis studies using a model 1,N2-propanodeoxyguanosine adduct suggest that these adducts are potential promutagenic lesions. The increased levels of the propano adducts in the tissue of carcinogen-treated animals also provide suggestive evidence for their roles in carcinogenesis. The involvement of these adducts in tumor promotion is speculated on the basis that oxidative condition in tissues is believed to be associated with this process.

The modifying effects of α-difluoromethylornithine (DFMO) on glandular stomach carcinogenesis after initiation with N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and sodium chloride were investigated in male outbred Wistar rats. Animals were simultaneously given MNNG solution (100 ppm) as their drinking water and diet supplemented with 10% sodium chloride for 8 weeks, and administered DFMO (dietary levels of 2000 ppm or 500 ppm) and tap water for the following 70 weeks. The DFMO treatment did not show any tendency to inhibit the development of gastric adenocarcinomas. The incidences and multiplicities of atypical hyperplasias in the glandular stomachs were also comparable in all groups of rats given MNNG/sodium chloride. Neither gastric carcinomas nor atypical hyperplasias were observed without the carcinogen treatment. Thus, DFMO did not exert any inhibitory effects when given during the post-initiation phase of two-stage glandular stomach carcinogenesis in rats initiated with MNNG and sodium chloride for 8 weeks.

Leiomyomas are well-circumscribed nodular tumors. Leiomyosarcomas are discretely nodular or diffuse gastric masses with varying degress of ulceration and may grow to occupy almost the entire stomach wall; they are usually situated intramurally although they may invade through to either surface. Leiomyosarcomas are a relatively rare finding in the rat stomach after administration of gastric carcinogens. At necropsy they appear as firm, lobulated, nonencapsulated fleshy masses, with varying degrees of hemorrhagic necrosis and cystic changes. This tumor resembles other sarcomas such as fibrosarcoma except that, in contrast to the latter, they have a more grayish color and a less firm consistency. Mucosal ulcerations are commonly present in advanced cases.

Adenomas are grossly observed as plaque-like or nodular lesions covered with glandular epithelium with a smooth and glossy or ulcerated surface. They are often seen as white or translucent nodules of various sizes. In some cases, the lesions appear as well-demarcated thickenings of the mucosa accompanied by polypoid structures on the surface, the thickening mainly being due to hyperplasia of foveolar epithelial cells. Adenomas are predominantly localized at the pyloric antrum, but they also occur in the fundic mucosa when treatment with mucosa-damaging agents such as iodoacetamide (Takahashi et al. 1976) is carried out prior to carcinogen treatment.

The carcinogenic potential of eight different compounds was assayed in a new medium-term carcinogenicity bioassay using d -galactosamine (DGA) as a non-surgical method to induce regeneration in place of partial hepatectomy (PH). Male rats were initially given a single i.p. injection (200 mg/kg) of diethylnitrosamine (DEN) and after 2 weeks on basal diet, received two i.p. injections of DGA (300 mg/kg) at the end of weeks 2 and 5. They were treated with one of the test compounds aflatoxin B 1 , benzo[ a ]pyrene, diethylstilbestrol, urethane, sodium saccharin, bucetin, D-mannitol and sodium chloride in the diet or basal diet alone for weeks 3–8. Carcinogenic potential was assessed by comparing the numbers and areas per cm 2 of glutathione S -transferase placental form-positive (GST-P+) foci in the livers of treated animals with those of the control animals given DEN/DGA alone. Positive estimations of carcinogenicity were obtained for the hepatocarcinogens aflatoxin B 1 , diethylstilbestrols or urethane, and for the non-liver carcinogen benzo[ a ]pyrene. Negative values were shown in rats treated with the non-carcinogens, d -mannitol and sodium chloride. The two other non-liver carcinogens sodium saccharin and bucetin, also did not exert positive effects in the system. The present data are consistent with findings in previous medium-term bioassays using PH. Our results thus confirm that the present bioassay protocol with repeated administration of DGA instead of PH may offer a new and sensitive non-invasive method to screen large numbers of environmental carcinogens.

Male Syrian golden hamsters were exposed for 1 or 2 weeks to smoke produced by commercial non-filter cigarettes for 5 consecutive days in a Hamburg type II smoking machine. Postmitochondrial fractions (S9) prepared from the liver, lungs, and pancreas were used in the Ames liquid incubation assay, in order to assess the effect of cigarette smoke (CS) on the metabolic activation of four groups of procarcinogens. The mutagenic activities of five heterocyclic amines on strain TA98 in the presence of liver S9 mix were induced up to 3.7 times above controls including sham smoke control, while no significant alteration of mutagenicity was observed with 3'-hydroxymethyl-N,N-dimethyl-4-aminoazobenzene and benzo[a]pyrene on TA98 or with N-nirosobis(2-oxopropyl)amine (BOP) on TA100. A similar stimulation of metabolic activation was also observed for 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) with S9 from the lungs but not from the pancreas. The mutagenic potential of 11 carcinogens including aflatoxin B1 (AFB1) and two other heterocyclic amines was also examined using liver S9 from male hamsters pretreated with phenobarbital (PB) or 3-methylcholanthrene (MC). The numbers of revertant colonies were much higher (2-20-fold) in the presence of MC-treated liver S9 than in the presence of PB-treated liver S9, except in the case of AFB1 which showed a higher mutagenicity with PB-induced S9. 7,8-Benzoflavone considerably inhibited the activities of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and Trp-P-1 in the presence of either untreated, MC- or CS-treated liver S9, whereas metyrapone was totally lacking this effect, indicating that cytochrome P450(CYP)1A1/1A2 isoforms of hamster liver are predominantly involved in the metabolic activation of these carcinogens. CS exposure of hamsters might selectively induce hepatic CYP1A2 which cannot activate BOP. Consequently, the present findings could explain, in part, the anticarcinogenic effect of CS on BOP-induced pancreatic tumors in hamsters. The findings further support the idea that CS markedly stimulates the metabolic activation of food-derived carcinogens, which may contribute to the overall carcinogenic effects of cigarette smoking.

The effects of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) administration during the post-initiation phase of carcinogenesis were investigated in hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). Female Syrian golden hamsters were given a single s.c. injection of BOP at a dose of 10 mg/kg and then administered 3 ppm (H) or 1 ppm (L) NNK in their drinking water for the following 87 weeks. Additional groups of animals received the BOP injection alone, or only the 3 or 1 ppm NNK treatments as BOP-negative controls. At week 88 of the experiment, all surviving animals were sacrificed and development of proliferative lesions was assessed histopathologically. The results showed no statistically significant influence on pancreatic adenocarcinomas or dysplastic lesions, although the incidence and the number of atypical hyperplasias in the pancreas head in the BOP/NNK (L) group was significantly increased as compared to BOP alone group values (P < 0.05). Similarly, the NNK treatments did not affect the incidences or multiplicities of neoplastic or hyperplastic lesions in the endocrine pancreas, lung, liver or kidney. Thus, the present experiment demonstrates that the tobacco-specific carcinogen NNK does not enhance BOP-induced hamster tumorigenesis when given in the promotion phase.

The influence of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, a mutagen in chlorinated water, on cell proliferation and lipid peroxidation in the glandular stomach mucosa was investigated in male 4-week-old Wistar rats. Animals were given 50 p.p.m., 25 p.p.m., 12.5 p.p.m., 6.25 p.p.m. or 0 p.p.m. of MX solution in their drinking water for 5 weeks. At the end of this period, cell proliferation in the mucosal epithelia of the gastric fundus was increased in a dose-dependent manner up to 25 p.p.m., at which dose the induction was statistically significant as compared with the control value (P < 0.05). The MX treatment was also associated with increased lipid peroxidation levels in the gastric mucosa as well as well as in the urine, with loose dose-dependence, although not at 50 p.p.m. Mucosal lipid peroxidation was significantly increased in animals given 25 p.p.m. as compared with controls (P < 0.05). Similarly, the levels of urinary lipid peroxidation were significantly higher in rats given 25 p.p.m. or 12.5 p.p.m. than in the controls (P < 0.05). Histopathologically, gastric erosion was noted in rats receiving 25 p.p.m. or more of MX. There were no statistical differences between groups for serum biochemical data. The results thus suggest that MX may exert a gastric tumor-promoting action in rats, even at low doses which do not give rise to toxic effects, because of the clear doseresponse relationship evident at low levels.

The influence of different doses of sodium chloride (NaCl) on glandular stomach carcinogenesis was examined in male outbred Wistar rats after initiation with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Rats were given 100 p.p.m. MNNG in their drinking water for 8 weeks and then fed a diet supplemented with NaCl at doses of 10, 5, 2.5 or 0% for the next 82 weeks. The administration of 10% and 5% NaCl significantly enhanced the development of gastric adenocarcinomas and adenomas in a dose-dependent manner. Similar but non-significant tendencies for increase were also seen in the group given 2.5% NaCl compared to the MNNG-alone group values. Clear linear correlations between incidences of adenocarcinomas and/or adenomas and the concentration of supplemented NaCl were found. Mesenchymal tumors were also induced in the stomach of rats given MNNG, although the incidence was not statistically different between groups. Independent of the MNNG treatment, urinary lipid peroxidation levels were significantly increased in the NaCl-treated groups as compared to the control values. Thus, the results in the present study indicate that NaCl exerts dose-dependent tumor promoting activity on gastric carcinogenesis in rats, even at doses as low as 2.5%, when given after MNNG initiation.

Binding of a specific antibody to proliferating cell nuclear antigen (PCNA) and staining of argyrophilic proteins associated with nucleolar organizer regions (AgNORs) were investigated in proliferative lesions induced by N-nitrosobis(2-oxopropyl)amine (BOP) in the hamster kidney. Thirty male Syrian golden hamsters were given three weekly s.c. injections of BOP (10 mg/kg body wt.) and sacrificed for characterization of proliferative changes 30 weeks after the first BOP treatment. Morphologically, lesions of the tubular epithelia were classified either as tubular adenoma or dysplasia, the latter being further classified into small cluster, acidophilic cell, clear cell and cystic types. Immunohistochemistry for PCNA revealed significant increases of cell proliferation activity in adenomas and acidophilic cell types of dysplasia, along with significantly elevated mean numbers of AgNORs per nucleus. The results thus indicate that the acidophilic cell type of dysplasia may be of prime significance as the preneoplastic renal lesion induced by BOP.

Monoclonal antibodies specific for N2,3-ethenodeoxyguanosine (N2,3-epsilon dGuo) and 1,N2-ethenodeoxyguanosine (1,N2-epsilon dGuo) were developed. In a competitive ELISA, 50% inhibition of binding of the N2,3-epsilon dGuo specific antibody (ETH1) was achieved with 18 fmol of N2,3-epsilon dGuo. Fifty per cent inhibition of the 1,N2-epsilon dGuo-specific antibody (ETH2) required 11 pmol 1,N2-epsilon dGuo. Immunoassays for N2,3-epsilon dGuo and 1,N2-epsilon dGuo in single-stranded DNA were developed using these antibodies. The immunoassays could detect as little as 48 fmol of N2,3-epsilon dGuo or 340 fmol 1,N2-epsilon dGUO in 25 micrograms of single stranded DNA. These assays and previously developed immunoassays for 1,N6-ethenodeoxy-adenosine (1,N6-epsilon dAdo) and 3,N4-ethenodeoxycytidine (3,N4-epsilon dCyd) were used to measure etheno adduct levels in DNA of cells exposed to chloroacetaldehyde. The cells used were V79 cells with an inactivated hprt gene and a single copy of the bacterial gpt gene (G12 cells). The most abundant etheno adduct was 1,N6-epsilon dAdo, followed by 3,N4-epsilon dCyd and N2,3-epsilon dGuo. 1,N2-epsilon dGuo was not detected in chloro-acetaldehyde-treated G12 cells. Chloroacetaldehyde was also shown to be mutagenic in these same cells.

The effects of soybean trypsin inhibitor (SBTI) administration during the promotion phase of pancreatic carcinogenesis were investigated. Female Syrian golden hamsters were given three weekly s.c. injections of N-nitrosobis(2-oxopropyl)amine (BOP) each at a dose of 10 mg/kg and then administered 5% SBTI diet for the following 37 weeks. Additional groups of animals received the BOP injection alone or the 5% SBTI diet alone as controls. At week 40 of the experiment, all surviving animals were killed and development of pancreatic lesions was assessed histopathologically. The results showed that the incidence of dysplastic lesions in hamsters of the BOP/SBTI group was significantly decreased as compared to that of the BOP group (P < 0.01). A similar but not significant tendency was also found for pancreatic adenocarcinomas. In addition, the number of dysplastic lesions in the pancreas head portion in the BOP/SBTI group were significantly decreased as compared to the BOP group value (P < 0.05). Furthermore, atrophic changes of the pancreatic exocrine tissue were more severe in the BOP group than in the BOP/SBTI group (P < 0.01), indicating that SBTI treatment gave effective protection against the replacement process of acinar cell induced by BOP. Thus, the present experiment demonstrated that SBTI can inhibit hamster pancreatic ductal carcinogenesis when given in the promotion phase, in clear contrast to the enhancing effects reported for preneoplastic acinar lesion development in rats.

The carcinogenicity of ferric chloride, a compound that is used as a food additive, a haemostatic or treatment for hypochromic anaemia, was examined in F344 rats of both sexes. It was dissolved in distilled water at levels of 0, 0.25 or 0.5%, and groups of 50 male and 50 female rats were given one of these solutions ad lib. as their drinking water for up to 2 yr. The mean body weights of the treated rats were lower than control group values for both males and females. A variety of tumours developed in all groups, including the control group, but all these neoplasms were histologically similar to those known to occur spontaneously in this strain of rats, and no statistically significant increase in the incidence of any tumour was found in the treated groups of either sex. Thus it is concluded that under the conditions of this experiment, ferric chloride exerts no carcinogenic potential in F344 rats.

The modulating effects of caffeine, nicotine, ethanol and sodium selenite on development of N-nitrosobis(2-oxopropyl)-amine (BOP)-initiated pancreatic tumors were investigated. Female Syrian golden hamsters were given s.c. injections of BOP (10 mg/kg body weight) or saline alone once a week for 3 weeks and then administered 2000 p.p.m. caffeine, 25 p.p.m. nicotine, 20% ethanol or 4 p.p.m. sodium selenite in their drinking water for the next 37 weeks. Control animals were given tap water alone after BOP initiation. Only the BOP-treated groups developed pancreatic adenocarcinomas and dysplasias. The multiplicity of pancreatic carcinomas was significantly higher (P less than 0.05) in animals receiving caffeine than in the controls. In addition, caffeine treatment slightly increased the incidence of carcinomas. Nicotine and ethanol also showed tendencies to enhance pancreatic carcinogenesis, although there were statistically no significant differences regarding lesion development. In contrast, sodium selenite administration was associated with a tendency for a decrease in the number of carcinomas and dysplasias. Thus, among these chemicals of obvious significance to human life-style, caffeine enhanced the development of pancreatic tumors when administered during the post-initiation phase in this hamster model.

The hepatocarcinogen NPYR is metabolically activated by alpha-hydroxylation mediated by cytochrome P-450 enzymes to yield a 4-oxobutylating agent and 2-butenal (crotonaldehyde). Both are reactive intermediates capable of modifying DNA with guanine either by simple alkylation or by Michael type addition, respectively. In order to assess the roles of these pathways in NPYR tumorigenesis, we are interested in identifying agents which can selectively modify one of these two pathways. In this study, we examined the effects of three thiols--(mesna), glutathione (Glu), and N-acetylcysteine (Nac)--on DNA adduct formation by alpha-acetoxyNPYR, a stable precursor of alpha-hydroxyNPYR. Calf thymus DNA isolated from incubation of alpha-acetoxyNPYR with or without thiol was hydrolyzed and analyzed for the adducts formed by alkylation (adducts 1 and 2) and Michael addition (adducts 3-5). The results showed that the addition of mesna completely blocked the formation of the crotonaldehyde-derived adducts 3-5, whereas it exerted little effect on the formation of the alkylated adducts 1 and 2. These results indicate the preferential conjugation of mesna with crotonaldehyde. In contrast, Nac had little selectivity on adduct formation; levels of adducts 1 to 5 were were reduced by 36-75%. These results suggest that Nac conjugated with both alkylating agent and crotonaldehyde. Similar to mesna, Glu blocked the formation of the crotonaldehyde-derived adducts (adducts 3-5) efficiently. However, unlike mesna, Glu inhibited the formation of adduct 1, while it did not inhibit the formation of adduct 2, although both adducts are presumably derived from the 4-oxobutylating agent.(ABSTRACT TRUNCATED AT 250 WORDS)

In assays of Areca-specific N-nitrosamines, 3-(methylnitrosamino)propionaldehyde (MNPA) exhibits higher cytotoxicity than nitrosoguvacine (NGC), nitrosoguvacoline (NG) and 3-(methylnitrosamino)propionitrile (MNPN). NGC is not mutagenic. However, NG is a weak carcinogen in F344 rats while MNPN is a potent carcinogen; MNPA had thus far not been tested. In this study MNPA was injected s.c. at a dose of 6.57 mg three times weekly for 15 weeks (total dose 2.6 mmol/rat). During the 100 weeks of the bioassay, the treated F344 rats, and especially the females, showed significantly less weight gain than the control animals, indicating high toxicity for MNPA at the tested dose. Upon termination of the bioassay, the MNPA-treated animals were found to have tumors of the lung, liver, nasal cavity, forestomach and kidneys. The control animals showed no tumors in these organs. The incidence of lung tumors in the MNPA group was statistically significant (P less than 0.025). The results of this study show that MNPA is a carcinogen in F344 rats.

Exposure to acrylamide (ACR) in foodstuffs has become a worldwide concern, and mean intake of ACR in infants and children is estimated to be 2- to 3-fold higher than that in adults when expressed on a body weight basis. To compare the susceptibilities to ACR-induced neurotoxicity and testicular toxicity between young and adult rats, 3- or 7-week-old male SD rats were given ACR at 0, 50, 100 or 200 ppm in the drinking water for 4 weeks, and histopathological examinations of the nervous and male reproductive systems were performed. In addition to scoring of gait abnormalities, neurotoxicity was quantitatively assessed with reference to nerve fiber density, percentages of degenerated axons in the sciatic nerves, and numbers of aberrant dot-like structures immunoreactive to synaptophysin in the cerebellar molecular layer. When compared to adult animals, mean daily intake of ACR per Kg body weight was higher in young animals at each dose. In both young and adult animals, gait abnormalities and histopathological changes suggestive of neurotoxicity including central chromatolysis of ganglion cells in the trigeminal nerves and an increase in degenerated axons in the sciatic nerves were evident from 100 ppm. Although signs of neurotoxicity were generally higher in young animals, the higher severity might reflect the larger amount of ACR intake in young animals. In the testis, marked degeneration and exfoliation mainly of spermatids were observed from 100 ppm onwards in young animals, whereas small numbers of exfoliated germ cells were found in adults cases at 200 ppm. These results suggest that the susceptibilities to ACR-induced neurotoxicity in young and adult rats are similar and that the neurotoxicity is correlated to intake of ACR per body weight. Regarding testicular toxicity, young animals are more susceptible than adults. It is evident that total ROS production increased with enhanced inflammatory status, suggesting a plausible mechanistic pathway between radiation-induced persistent inflammation and cancer.

Background Recently, manufactured nano/microparticles such as fullerenes (C60), carbon black (CB) and ceramic fiber are being widely used because of their desirable properties in industrial, medical and cosmetic fields. However, there are few data on these particles in mammalian mutagenesis and carcinogenesis. To examine genotoxic effects by C60, CB and kaolin, an in vitro micronuclei (MN) test was conducted with human lung cancer cell line, A549 cells. In addition, DNA damage and mutations were analyzed by in vivo assay systems using male C57BL/6J or gpt delta transgenic mice which were intratracheally instilled with single or multiple doses of 0.2 mg per animal of particles. Results In in vitro genotoxic analysis, increased MN frequencies were observed in A549 cells treated with C60, CB and kaolin in a dose-dependent manner. These three nano/microparticles also induced DNA damage in the lungs of C57BL/6J mice measured by comet assay. Moreover, single or multiple instillations of C60 and kaolin, increased either or both of gpt and Spi- mutant frequencies in the lungs of gpt delta transgenic mice. Mutation spectra analysis showed transversions were predominant, and more than 60% of the base substitutions occurred at G:C base pairs in the gpt genes. The G:C to C:G transversion was commonly increased by these particle instillations. Conclusion Manufactured nano/microparticles, CB, C60 and kaolin, were shown to be genotoxic in in vitro and in vivo assay systems.

Four different experiments were performed in order to examine the modifying effects of chlorogenic acid (CA), reserpine, polyprenoic acid (E-5166), and coffee on chemical carcinogenesis in rats or hamsters. Experiment 1: The numbers of hyperplastic liver cell foci and the incidence of colon tumors in male and female Syrian golden hamsters given a single intraveneous injection of methylazoxymethanol (MAM) acetate and then fed the diet containing 0.025% CA for 24 wk were significantly lower than those of hamsters given MAM acetate alone. Experiment 2: The incidence of altered hepatocellular foci in female ACI/N rats given N-2-fluorenylacetamide (FAA, 0.02% in diet) for 10 wk and reserpine (weekly subcutaneous injections, 1 μg/g body weight) during or after (17 wk) FAA exposure was significantly lower than that of rats given FAA alone. Experiment 3: The number of hepatocellular foci in male ACI/N rats given 0.02% FAA diet for 13 wk and E-5166 by gavage (40 mg/kg body weight, 3 times/wk) for 16 wk after the end of FAA exposure was significantly smaller than that in rats given FAA diet alone. Experiment 4: Incidences of liver tumors and hepatocellular foci of rats given concurrent dietary administration of aminopyrine (0.01%) and sodium nitrite (0.1%) and coffee solution as a drinking water for 630 da were significantly lower than those of rats given aminopyrine and sodium nitrite. Thus, the tested compounds had inhibitory effects on chemical carcinogenesis in liver or colon.

Thyroid cell proliferation caused by environmental compounds is well known to be associated promotion of carcinogenesis. For example, kojic acid, a secondary fungal metabolite, induces cell proliferation in rat thyroid follicular epithelium, and promotes thyroid carcinogenesis after initiation with N-bis(2-hydroxypropyl)nitrosamine (DHPN). This was due to negative feedback through the pituitary-thyroid axis caused by inhibition of iodide uptake and iodine organification. Subcutaneous cholesterol pellets containing 17β-estradiol 3-benzoate also enhance rat thyroid carcinogenesis in ovariectomized female rats initiated with DHPN, although this was not the case with weak endocrine disrupting chemicals such as methoxychlor, atrazine and bisphenol A, which rather caused inhibition, possibly due to decrease in body weight gain. A high soybean diet enhances thyroid cell proliferation with increase in serum TSH level in synergism with a low iodine diet, presumably soybean diet primarily stimulate serum TSH release from the pituitary specifically under iodine deficiency conditions.

The potential toxicity oftrans-4-hydroxy-2-nonenal (HNE), a product formedin vivo during lipid peroxidation, which is also present in foods, was investigated in Fisher 344 rats. Five groups of five male rats each were given by gavage 1000, 300, 100, 30 or 10 mg/kg body weight HNE dissolved in 0.5 mL corn oil. The sixth group, the control, received corn oil alone. Two rats died 6 and 8 hr after being treated with 1000 mg/kg HNE. These two rats showed extensive acute tubular necrosis of the kidney, but had very little liver damage. Diffuse liver cell necrosis was observed in a dose dependent manner in all the rats killed 14 days after treatment, whereas renal change was mild. Interestingly, body weight of the lowest dosage group was significantly higher than that of the control group at termination of the experiment. The results of this study show that HNE has almost the same toxicity as other enals, such astrans-2-heptenal, and that kidney and liver are the main organs affected by toxicity of HNE. Although animals may have efficient defense systems, such as glutathione, to detoxify low to moderate dosages of HNE, at high doses of HNE this defense system is overwhelmed, resulting in serious renal and hepatic damage.

A male case of Alagille's syndrome associated with a hamartomatous nodule of the liver is described. The patient developed jaundice soon after birth, and was diagnosed as the syndrome with signs such as paucity of the intrahepatic bile ducts, pulmonary stenosis and embryotoxon in the cornea at 15 years of age. The liver was examined in recurrent biopsies and other tests. However, no evidence of liver cirrhosis was confirmed until his 15th year. The patient died of hepatic dysfunction when he was 17 years old. At autopsy, a large hamartomatous nodule was found in the liver showing biliary cirrhosis. Morphology of the nodule resembled that of focal nodular hyperplasia. Abnormalities of the large vessels were noted around the liver. Vascular abnormalities were also seen in the mass. The relation of these vascular abnormalities to etiological background of the syndrome and occurrence of the nodular lesion is discussed.

A case of a rare primary cardiac tumor in a 46-year-old woman is described. The tumor arose from the left atrium and was histologically composed of multiple mesenchymal elements of fibrosarcoma, rhabdomyosarcoma, chondrosarcoma, myosarcoma, and liposarcoma. Metastasis of this tumor occurred in the left femur, lung, and hilar lymph nodes after the second heart operation. Histogenesis of malignant mesenchymoma was considered with a survey of the literature.

Promoting effect of quercetin in the intestinal tract was examined in Sprague-Dawley strain rats. The rats were injected with methylazoxymethanol acetate (MAM) in saline solution at 25 mg/kg body weight once a week for 3 weeks and fed a diet containing 1% quercetin for the following 459 days. Most tumors found in this experimental group were also found in the group injected with MAM alone and there was no significant difference in tumor incidence between these two groups. No tumors were found in the group fed the 1% quercetin diet alone. Thus, quercetin was shown to lack of promoting activity on MAM-induced intestinal carcinogenesis in Sprague-Dawley rats.

多量の心嚢液貯留をきたし, 心嚢穿刺液細胞診にて多数の異型細胞を認め, 剖検により縦隔起源のembryonal carcimomaと確定し得た中年女性の症例を, 主として心嚢穿刺液細胞所見について報告する.症例は55歳の女性で, 嗄声と咳嗽の症状で経過中, 心タンポナーデを呈した.心嚢穿刺を施行すると多量の血性液が吸引され, 細胞診上多数の腺型悪性細胞を認めたが, 原発巣は明らかにされなかった.腫瘍細胞はおおむね腺管様ないし乳頭状配列を示す細胞集塊としてみられ, ライトグリーン好性の細胞質と比較的大小不同に乏しい類円形核を有していた.核膜は明瞭で, 肥大した類円形の核小体を1～2個認めた.また, 彎入核を有する細胞も散見された.発症後3ヵ月で死亡し, 剖検すると, 前上縦隔に6×4×4.5cm大の腫瘍があり, 心嚢へ直接浸潤していた.組織学的に, 腫瘍は乳頭状・腺管様・充実性増殖を示すembryonal carcinomaの像で, PAS反応は陰性であった.また, PAP法による免疫染色では, AFP・HCG・胎盤性アルカリフオスファターゼのいずれも陰性であった.両側卵巣に腫瘍性変化および瘢痕巣は認められなかった.

The number of silver-stained nucleolar proteins (AgNOR) was counted in preneoplastic and neoplastic rat liver lesions induced by N-2-fluorenylacetamide (FAA) and was compared with that of bromodeoxyuridine (BrdU)-incorporating cells detected immunohistochemically using monoclonal antibody against BrdU. Male ACI/N rats were given diet containing 200 ppm FAA for 12, 16 or 20 weeks to induce hepatocellular foci and tumors. The mean numbers of AgNOR stained by a one-step silver colloid method and BrdU-labeling indices in various liver cell lesions were as follows: nontreated liver (n = 20), 1.20 and 0.08; nonlesional areas (n = 20), 1.33 and 0.13; altered liver cell foci (n = 80), 2.04 and 4.05 [eosinophilic cell type (n = 20), 1.78 and 1.82; clear cell type (n = 20), 1.45 and 1.77; basophilic cell type (n = 20), 1.99 and 4.58; hyperbasophilic cell type (n = 20), 2.94 and 8.02]; neoplastic nodules (n = 10), 3.11 and 2.99; hepatocellular carcinomas (n = 10), 7.22 and 8.29. Thus, the mean number of AgNOR and the value of BrdU-labeling index were well correlated and both values showed a stepwise increase from normal liver cells to liver cell carcinoma, although some scatter was present. These data suggest that mean number of AgNOR may reflect the cellular kinetics in rat hepatocarcinogenesis, and the one-step silver colloid method for demonstration of AgNOR may therefore be a simple and useful staining to examine the proliferative nature of cells.