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The histogenesis of 3 types of rat renal cell tumors (basophilic cell, clear cell, and oncocytic) was stereologically analyzed, with particular attention paid to transitions from normal tubules. Early nitrosamine-induced preneoplastic lesions, including dysplastic tubules (altered tubules), epithelial hyperplasias, and small adenomas, were reconstructed using serially sectioned specimens processed for carbonic anhydrase type II (CA) and periodic acid-Schiff (PAS) (CA-PAS) double staining to allow easier distinction of the nephron segments: Proximal tubules had a PAS-positive brush border and were weakly positive for CA in the cytoplasm; distal tubules were PAS negative and weakly positive for CA; collecting ducts were PAS negative and strongly positive for CA. Similarly, cytochrome c oxidase (CytOx) and CytOx-PAS double staining was also applied to confirm the character of oncocytic lesions. All basophilic lesions (7 of 7) showed transition to proximal tubules. Clear cell lesions positive for CA, on the other hand, showed transition to distal tubules in 4 of 9 (44.4%) lesions and to collecting ducts in 4 of 9 (44.4%) lesions, but in only 1 of 9 (11%) to a proximal tubule. All oncocytic lesions (16 of 16), characterized by positivity for both CA and CytOx, showed transition to collecting ducts. The results indicate that the origins of renal cell neoplasia are proximal tubules for the basophilic cell lesions, either proximal or distal tubules for their clear cell counterparts, and collecting ducts for oncocytic lesions.

The presence of ras family and p53 gene mutations in rat forestomach, intestine and liver tumors and soft tissue sarcomas induced by N-methyl-N-nitrosourea (MNU) was examined using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing analysis. In the forestomach squamous cell carcinomas (SCC), Ha-ras and p53 mutations were detected in 2 (40%) and 4 (80%) of 5 cases, respectively. The figures for Ki-ras and p53 gene mutations in adenocarcinomas of the large and small intestines were 3 (18.8%) and 5 (31.3%) of 16 cases. Soft tissue sarcomas in different sites were found to have mutations of Ki-ras in 7 (23.3%) and of p53 in 9 (30%) of 30 cases. One forestomach SCC and 2 soft tissue sarcomas had double p53 mutations in different exons. Single cases of forestomach SCC and intestinal adenocarcinoma had mutations in both Ki-ras and p53 genes. No mutations were found in counterpart benign tumors or hepatocellular adenomas. The p53 mutation spectrum revealed preferential clustering within exon 8 for the forestomach SCCs, and exons 5 and 8 for the intestinal adenocarcinomas, whereas the distribution was evenly spread through exons 5 to 8 in soft tissue sarcomas. All the detected ras or p53 mutations were G:C to A:T transitions. These results indicate firstly that specific Ki-ras, Ha-ras and p53 gene mutations in MNU-induced lesions are related to particular alkylation sites (G:C to A:T transitions) and secondly, although not essential, Ki-ras, Ha-ras or p53 gene mutations may be involved in the progression stage of forestomach, intestine and soft tissue neoplasms induced by MNU.

To assess mechanisms of chemoprevention of hepatocarcinogenesis by trans-beta-carotene (beta-C), DL-alpha-tocopherol (alpha-T), and freeze-dried whole leaves of Kidachi aloe (Aloe), formation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-DNA adducts was measured by 32P-post-labeling analysis, and CYP1A1 and CYP1A2 protein levels were analyzed by ELISA. Group 1 rats were fed diet containing 0.02% beta-C, 1.5% alpha-T or 30% Aloe over an 8-day period, while group 2 was given basal diet alone. On day 7, all animals were subjected to two-thirds partial hepatectomy (PH). Twelve hours after PH, they received a single dose of the carcinogenic food pyrolysate IQ (100 mg/kg) intragastrically, to initiate hepatocarcinogenesis. Rats were killed 6, 12, 24 and 48 h after IQ administration. The levels of adducts, expressed as relative adduct labeling values in rats treated with beta-C, alpha-T and Aloe, were decreased as compared with the control group at hour 24 (36 h after PH), with a significant difference in the case of the beta-C group (46.4% of the control value). Similarly, all showed a tendency for decrease at hour 48. Furthermore, the levels of CYP1A2, known to be responsible for activation of IQ, showed a significant reduction at hour 24. It is concluded that beta-C, and possibly also alpha-T and Aloe, have the potential to reduce IQ-DNA adduct formation, presumably as a result of decreased formation of active metabolites. The results may explain, at least in part, the previously observed inhibitory effects of these compounds on induction of preneoplastic hepatocellular lesions.

In a development trial for an initiation bioassay system, 7 known carcinogens and 1 suspected carcinogen were examined. In experiment 1, group 1 animals were initially subjected to partial hepatectomy (PH) 12 h before administration of diethylnitrosamine, 2-amino-3-methylimidazo[4,5-f]-quinoline (IQ), captafol, alpha-hexachlorocyclohexane or diethylstilbestrol (DES), then 2 weeks later underwent a promotion procedure comprising administration of phenobarbital (0.05% in diet) for 8 weeks and D-galactosamine (300 mg/kg, i.g.) at week 3. Group 2 received the promotion protocol alone as in group 1. Initiating potential was assayed on the basis of significant increase in values of preneoplastic placental form glutathione S-transferase-positive (GST-P+) foci of more than 3 cells in cross section at week 10. Numbers and areas of GST-P+ foci in group 1 given IQ, captafol and DES were significantly increased as compared to group 2, confirming the validity of the protocol as an initiation assay. In Experiment 2, group 1 rats were subjected to PH and 12 h later received a suspected carcinogenic mixture of opium pyrolysate (OP) or carcinogenic pesticide p,p'-dichloro-diphenyltrichloroethane or hexachlorobenzene. Application of a modified promotion procedure comprising cholic acid (0.15%) and carbon tetrachloride (1 ml/kg, i.g.) revealed significant initiation potential for OP. Overall the results indicate that the current protocols may be useful for detection of the initiation potential of carcinogens irrespective of their mutagenicity.

Inhibitory effects of freeze-dried Aloe arborescens Miller var. natalensis Berger (Kidachi aloe) whole leaf powder (Aloe) on induction of preneoplastic glutathione S-transferase (GST-P) positive hepatocyte foci GST-P + were studied in male rats. Experiment 1: Group 1 was fed a diet containing 30% Aloe for 8 days. At day 7, the carcinogen, 2-amino-3-methylimidazo(4,5-f)quinoline(IQ, 100 mg/kg, i.g., one dose), was given 12 h after partial hepatectomy (PH) for initiation, followed by phenobarbital (PB) and D-galactosamine for promotion and then killed at week 11. Experiment 2: Group 1 was given diethylnitrosamine (DEN, 200 mg/kg, i.p.) for initiation then a diet containing 30, 20 or 10% Aloe during weeks 3-8, with PH at week 3. In both experiments, groups 2 and 3 were treated as in group 1 without Aloe or carcinogens

Retinal degeneration induced by a single parenteral dose (40 mg) of N-methyl- N-nitrosourea (MNU) was studied in rats and rabbits. Sequential observations showed that severe pathological changes, that is, complete or widespread destruction of the photoreceptor layer and the outer nuclear layer of the retina, occurred in both animals by 72 hr after the administration of MNU. At week 5, at the end stage of the retinal degeneration induced by MNU, thin remnants remained with the inner nuclear layer in direct contact with the pigment epithelium. An additional immunohistochemistry study using antibodies against 7-methyldeoxyguanosine (7-mdGua), revealed the presence of high levels of 7-mdGua DNA adducts in the nuclei of the outer nuclear layer cells. This finding suggests that the alkylation of the outer nuclear layer by MNU was the direct cause of the retinal degeneration seen in these animals.

The prevalence of Ki-ras, Ha-ras and N-ras point mutation within exons 1 and 2 was studied in 17 cases of renal cell tumors (8 carcinomas and 9 adenomas) induced by N-ethyl-N-hydroxyethyl-nitrosamine or N-nitrosomorpholine. DNA samples prepared from acetone-fixed, paraffin-embedded tissues were amplified by means of the polymerase chain reaction, and point mutations at codons 12, 13 and 61 were analyzed by direct sequence methods with oligonucleotide primers. No mutations were detected in any of the renal tumors. The results thus indicated that ras family point mutation is not necessary for kidney tumor development in rats, supporting the view that ras mutations may not be generally relevant to neoplastic development in various organs in different species.

Hepatocyte growth factor (HGF), a potent mitogen for adult rat hepatocytes in primary culture, has previously been shown to be primarily expressed in the nonparenchymal cells of the liver. Using polyclonal antisera against human and rat HGFs we studied the tissue distribution of HGF immunohistochemically and found the most intense staining in the pancreas islet cells in both man (autopsy cases) and the rat. Differential localization of 4 pancreas islet hormones, glucagon, insulin, somatostatin and pancreatic polypeptide, revealed HGF to be preferentially expressed within the glucagon-positive cells. The results indicate that HGF is primarily produced or stored in A-cells and may act as a growth factor in a paracrine and an endocrine fashion, like various other hormones.

The spontaneous photon emission (chemiluminescence) from Drosophila melanogaster fed chemical mutagens, polycyclic aromatic hydrocarbon quinones, and a carcinogenic bracken fern was studied. The fly chemiluminescence was evidently enhanced by mutagen or carcinogen administration and was increased proportionally to the administered amount of tested compound. Strong chemiluminescence was observed especially at the larval stage. Living larvae emitted stronger chemiluminescence than their homogenate. The chemiluminescence from Drosophila melanogaster fed polycyclic aromatic hydrocarbon quinones showed a linear relation with the mutation frequency in the Drosophila wing spot test. The chemiluminescence from flies fed a bracken fern decreased by the addition of free radical scavengers and active oxygen quenchers. The phosphatidylcholine hydroperoxide concentration in the flies was increased proportionally with the chemiluminescence intensity. It seems that the free radical formation is stimulated as shown by the enhanced chemiluminescence in mutagen- or carcinogen-dosed flies, and as a result, lipid peroxide accumulation accompanies mutation in Drosophila melanogaster.

Carcinogenicity of Agaricus bisporus, the edible mushroom, was studied in rats. Female Charles River Sprague - Dawley rats (CD rats) were given a diet containing a 30% dry powder of A. bisporus for 500 days until the termination of the experiment. A control group was given a basal diet without A. bisporus. The rats in the experimental group had mammary tumor, thymoma, adrenal adenoma and pituitary adenoma. However, there was no significant difference in the incidence of these tumors between the experimental group and control group. No carcinogenic activity of A. bisporus was observed in this experiment.

Bilobol, isolated from ginkgo fruit pulp, has been noted to be a strong skin irritant like 12-O-tetradecanoylphorbol-13-acetate (TPA), a tumor-promoter in the skin. A comparative investigation of morphological changes induced by bilobol and TPA induced in the skin of CD-1 mice, and an assessment of the skin tumor promoting potential of bilobol were therefore performed. In experiment I, mice received a single application of 2.5, 50 or 1000 micrograms of bilobol, or 0.1 or 2.5 micrograms of TPA on the right ear. The 50 or 1000 micrograms bilobol and 2.5 micrograms TPA doses caused ear redness, epidermal thickening and inflammatory infiltration. The dose of 2.5 micrograms of TPA, which is usually used as tumor promoter in skin carcinogenesis, was equivalent to 50 micrograms of bilobol in irritant effect. Thus, 50 micrograms of bilobol was used for the promotion testing (experiment II) in CD-1 mice initiated with 100 micrograms of 7, 12-dimethylbenz[a]anthracene (DMBA). Treatment with either 10 or 50 micrograms bilobol twice a week for 30 weeks did not result in any tumor development, thus suggesting that bilobol is not a complete promoter of skin carcinogenesis, despite generation of inflammation.

We examined the modifying effects of freeze-dried whole-leaf Aloe arborescens Miller var. natalensis Berger (designated as 'ALOE') on N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG)-induced duodenal tumorigenesis in C57BL/6 mice. Experiment 1: Male mice were given ENNG in drinking water for the first 4 weeks, and then 10% ALOE in basal diet for 16 weeks. Experiment 2: Female mice were given ENNG for 5 weeks, and then 5%, 1% or 0.2% ALOE in the diet were given for 15 weeks. In Experiment 1, the tumor incidence and tumor multiplicity (tumors per mouse) of the duodenum in the ENNG + 10% ALOE group were significantly decreased compared with that in the ENNG alone group. Erythrocyte polyamine levels in the ENNG + 10% ALOE group were also significantly decreased. In Experiment 2, the incidence of duodenal tumors in the ENNG + 5% ALOE group were significantly decreased compared with that in the ENNG alone group. These results indicated that ALOE, especially at 10% in the diet, inhibits ENNG-induced duodenal tumorigenesis in mice.

BACKGROUND. Pancreaticobiliary maljunction (PBM), an anomalous union of the pancreatic duct with the common bile duct, has frequently been shown to be associated with biliary carcinoma. However, the mechanism of carcinogenesis is unknown. METHODS. Mutations of the K-ras oncogene were examined in cancerous and noncancerous biliary tract epithelium of 20 patients with PBM by an extraction of DNA from surgically resected histologic specimens. DNA was analyzed by a polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) method and direct sequencing. RESULTS. An abnormally mobilized DNA band was detected not only in cancerous epitlielium but also in hyperplastic, metaplastic, and inflammatory epithelium of the gallbladder and/or common bile duct in patients with PBM. Among the biliary epithelium of patients with PBM, point mutation of K-ras oncogenes were detected in 4 of 5 (80%) cancerous epithelium, 7 of 12 (58%) hyperplastic and metaplastic epithelium, and 8 of 18 (44%) inflammatory epithelium, whereas no point mutation of the K-ras oncogene was detected in the gallbladder epithelium in 3 control patients without PBM. Direct sequence analysis of the K-ras oncogene revealed the mutation at codon 12 substituting the wild-type glycine (GGT) for aspartic acid (GAT) in all cancerous lesions of patients with PBM. Simultaneous two-point mutations from the wild-type glycine (GGC) to arginine (CGC) at codon 13 associated with the mutation at codon 12 were also found in one case of gallbladder carcinoma and one case of bile duct carcinoma. CONCLUSIONS. K-ras gene mutation is involved in the carcinogenesis of biliary tract epithelium in patients with PBM, and appears to be a high risk factor for carcinogenesis of the biliary tract.

Inhibitory effects of naturally occurring antioxidants on the initiation stage of hepatocarcinogenesis were studied. Group 1 rats were given a diet containing beta-carotene (beta-CT, 0.02%), alpha-tocopherol (alpha-TP, 1.5%), glutathione (GLT, 5%), vanillin (VNL, 1%), quercetin (QCT, 1%) or ellagic acid (ELA, 1%), or 3 doses of diallyl sulfide (DAS, 200 mg/kg, i.g.) over an 8-day period. On day 7, the animals received a single dose of 2-amino-3-methylimidazo[4,5-f] quinoline (IQ, 100 mg/kg, i.g.), 12 h after two-thirds partial hepatectomy for initiation and 2 weeks thereafter, were placed on promotion regimen comprising phenobarbital (0.05% in diet) and a single dose of D-galactosamine (100 mg/kg, i.p.). Groups 2 and 3 were treated as described for Group 1, but without test material or IQ, respectively. Survivors were killed at week 11 and antioxidant influence was assessed by comparing values for preneoplastic glutathione S-transferase placental form-positive (GST-P+) foci between Groups 1 and 2. All lesions larger than 70 microns in diameter consisting of approximately 5 cells in cross section were counted. Numbers of GST-P+ foci/cm2 in Group 1 were: beta-CT, 7.99; alpha-TP, 8.21; GLT, 9.71; DAS, 10.37; VNL, 10.57; QCT, 11.1; ELA, 12.5 (n = 11-15). All, except ELA, showed a significant decrease as compared with the Group 2 value of 14.54 (n = 15). Only beta-CT showed a significant decrease for the area value. This is the first report to show that beta-CT, alpha-TP, GLT, DAS, VNL, QCT exert inhibitory effects on initiation of hepatocarcinogenesis by the food carcinogen IQ, suggesting that these antioxidants might find application as chemopreventive agents. Furthermore, the current protocol proved practical for the assessment of chemopreventive agents within 11 weeks, a relatively short period.

A high intake of salted food is thought to be related to the high incidence of stomach cancer in Japan. In the present study, female F344 rats were divided into four groups. They were fed a nutritionally deficient purified diet (Group 1) and standard purified diet (Group 3) for 113 weeks and the same diets supplemented with salted cuttlefish guts, broiled, salted, dried sardines, pickled radish, and soy sauce (Groups 2 and 4). The incidence of papillomas and ulcers of the forestomach was highest in Group 4, which was given the standard diet supplemented with the salty food materials (p less than 0.05). These results suggest the importance of salted food as a suspicious causal factor in human stomach cancer in Japan.

Two new p-hydroxystyrene glycosides, ptelatoside-A and ptelatoside-B were isolated from the carcinogenic fraction of aqueous extracts of bracken, Pteridium aquilinum var. latiusculum, and their str...

The sulfated polysaccharides degraded carrageenan and dextran sulfate sodium were studied for genotoxicity using DNA repair tests employing cultured rat hepatocytes or intestinal mucosal cells. No evidence of unscheduled DNA synthesis was obtained. In addition, both alone and in combination with the comutagen norharman, these substances were nonmutagenic in the Salmonella microsome/mutagenicity test. These findings suggest that the carcinogenicity of the sulfated polysaccharides may be due to nongenotoxic mechanisms.

The carcinogenicity of Farfugium japonicum and Senecio cannabifolius was studied in ACI rats. In Group I, rats were given a diet containing 20% Farfugium japonicum. Groups II, III, IV and V were given diets containing 8%, 4%, 1% and 0.2% Senecio cannabifolius until the end of the experiment, respectively. The experiment was terminated after 480 days, except for Group V which was terminated 560 days after the start of feeding. Hemangioendothelial sarcoma of the liver and liver cell adenoma were induced in Groups I, IV and V. All rats in Groups II and III died of hepatotoxicity within a short period.

Stereochemistry at C-18 of petasitenine, the carcinogenic alkaloid isolated from Petasites japonicus Maxim. was established by chemical and spectral means: the structure of petasitenine was thus determined completely, which is represented by (1). Transformation of petasitenine (1) into senkirkine (3) was achieved by low valent tungusten complexes.

Acute bracken fern toxicity in a calf was reproduced with ptaquiloside, a norsesquiterpene glucoside, isolated from the boiling water extract of bracken fern. Ptaquiloside was dissolved in 500 ml of saline and administered by drench at increasing dosages for six days out of every seven for the following periods: 400 mg/day for 24 days, 800 mg/day for 14 days and 1600 mg/day for four days. Neutrophilic granulocytes began to decrease markedly around 50 days after the start of the experiment, and granulocytopenia continued for a further 35 days until the autopsy, despite the discontinuance of ptaquiloside administration. Thrombocytes showed a relatively slow depression and reached 1 X 10(5)/mm3 at the lowest level. The calf was autopsied 86 days after the start of administration of ptaquiloside. Sternal bone marrow was found to be mostly replaced with fat marrow and only small foci of erythropoietic cells and a small number of megakaryocytes remained.

The effect of vitamin A deficiency on the carcinogenicity of betel quid was studied, using long-term feeding of vitamin-A-deficient and -sufficient diets with and without betel nut and calcium hydroxide in ACI rats. A high incidence of focal epithelial hyperplasia was observed in the upper digestive tract (tongue, buccal oral mucosa, esophagus, and forestomach) of rats in the group given the vitamin-A-deficient diet mixed with betel nut and calcium hydroxide. The vitamin-A-deficient group also showed a high incidence of squamous papilloma in the tongue, buccal mucosa, and forestomach. The incidence of hyperplastic lesions of the tongue and buccal oral mucosa was significantly higher in this group than in the group receiving the vitamin-A-sufficient diet with betel nut and calcium hydroxide. These results suggest that the vitamin-A-deficient condition enhanced the growth of epithelial hyperplasia that was due to the administration of the betel quid ingredients. However, vitamin A did not protect against the development of altered liver cell foci, which were frequently seen with a small number of hepatocellular neoplasms in all groups given the diets containing betel nut and calcium hydroxide (both vitamin-A-deficient and -sufficient groups).

Among the various kinds of spices tested, the aqueous extracts of dill weed from Anethum graveolens L. and dill seeds from A. sowa D.C. (Umbelliferae), exhibited a mutagenicity to Salmonella typhimurium, strains TA98 and TA100. The aqueous methanol extracts were fractionated by the mutation assay using the strain TA98 with S-9 Mix. Isorhamnetin 3-sulfate (persicarin) and quercetin 3-sulfate were characterized as the mutagenic principles. Carcinogenicity was not observed for dill weed and seeds when the diets containing these in 33% were administered for 450 and 410 days, respectively, to the inbred strain ACI rats.

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.

We examined the carcinogenicity of mioga to the urinary bladder of male Fischer-344 rats with vesical calculi induced by dimethyl terephthalate (DMT). Although urinary bladder papilloma and hyperplasia were induced in rats fed on DMT and mioga diet alternately, the carcinogenic activity of mioga was not found.

An unstable norsesquiterpene glucoside with a novel illudane skeleton, ptaquiloside ( 1 ) has been isolated from bracken fern, Pteridium aquilinum var. latiusculum and the planar structure has been established on the basis of spectral and chemical means.

Isolation of the carcinogen in the boiling water extract of bracken fern was conducted by following the active principle with a carcinogenicity bioassay. Fractionation of the bracken extract was carried out using adsorption on resin (Amberlite XAD-2 and TOYOPEARL HW-40 (c] and organic solvent extraction. A diet containing each of the fractions was given to 7 female Charles River Sprague-Dawley rats (CD rats) of 4 weeks old, except for the second fraction. All 7 rats given the last carcinogenic fraction developed mammary and intestinal tumors and 5 rats had urinary bladder tumors. Ptaquiloside (PT) which induced mammary cancer in female CD rats and rho-hydroxystyrene glycosides were isolated from this fraction.

Quercetin and kaempferol were tested for carcinogenicity in rats of both sexes. In Experiment I, 0.1% quercetin or control diet was given to Fischer 344 rats for 540 days. In experiment II, 0.04% kaempferol or control diet was given to ACI rats for 540 days. In both experiments, most tumors found in the experimental groups were also found in the corresponding control groups, and there were no statistical differences in the incidences of tumors in the experimental groups and the respective control groups. Quercetin and kaempferol were not shown to be carcinogenic to rats under these conditions.

Interaction between quercetin and superoxide radicals was investigated using xanthine-xanthine oxidase system and potassium superoxide as superoxide radical generators. Superoxide radical scavenging action of quercetin was demonstrated by measurement of the electron spin resonance spectrum of the 5-hydroperoxy-2,2-dimethyl-1-pyrrolidinyloxyl adduct. Degradation of quercetin by the radicals was demonstrated spectrophotometrically. Reduction of the quercetin mutagenicity by the radicals was demonstrated in the Salmonella typhimurium strain TA 98 by the Ames test.

4 pyrrolizidine alkaloids, heliotrine, lasiocarpine, petasitenine, and senkirkine, were tested for their effects of V79 Chinese hamster cells. All the alkaloids produced cytoplasmic vacuolization, and caused cellular and nuclear enlargement. Chromosomal aberrations were induced in cells treated with the alkaloids. Heliotrine and petasitenine induced interchromosomal exchanges, and lasiocarpine and senkirkine caused chromatid gaps. All the alkaloids induced an 8-azaguanine-resistant mutation in V79 cells by direct treatment for 48 h. Mutation was also induced by treatment with the alkaloids for 1 h in the presence of a metabolic activation system.

The genotoxicity of cycasin was examined in the standard hepatocyte primary culture (HPC)/DNA repair test and in the test supplemented with β-glucosidase. Generally, no DNA repair was elicited by cycasin in the standard test except for one assay which showed a strong response. With the addition of β-glucosidase to the test medium, cycasin elicited DNA repair with clear dependence on both dose and amount of β-glucosidase. These results indicate that supplementation of the HPC/DNA repair test with the appropriate glucosidase should be useful in detecting potentially genotoxic glucosides and suggests that supplementation with other specific enzymes could compensate for extrahepatic biotransformation processes required prior to final activation by hepatocytes.

Two new pyrrolizidine alkaloids revealing strong hepatotoxic activity were isolated from Petasites japonicus Maxim., and their structures were deduced to be (3) and (4), respectively based on chemical and spectral evidence.

The genotoxicity of ptaquiloside (PT), recently isolated from bracken fern and shown to be carcinogenic, was examined by means of the hepatocyte primary culture/DNA-repair test. PT elicited clear unscheduled DNA synthesis with a dose-response effect. The result indicates that PT is a genotoxic carcinogen.

The carcinogenicity of vicia, galanga, lathyrus and lycium, which are plants used as human food or in folk medicine, and of caffeic acid and prunasin, which are plant constituents, was examined in an inbred strain of ACI rats. Fresh plant materials were dried, milled and mixed with the rat basal diet in the ratio of 16% and 33% of the total. The plant constituents, caffeic acid and prunasin, were mixed with the basal diet in the ratio of 0.5% and 0.03%, respectively. These diets were administered to rats for periods ranging upward from 180 days. Carcinogenic activity was not observed with any of the plants or plant constituents.

Some sulfated polysaccharides, such as d-CGN, APS, and DSS, have carcinogenicity to the rat colorectum. These materials first induced colitis, secondly squamous metaplasia, and finally tumors at the colorectum. Initially, colitis was located in the columnar epithelium of the rectum and extended proximally thereafter. Squamous metaplasia persisted in almost all experimental rats and progressed irreversibly. The tumors were adenoma, adenocarcinoma, squamous cell papilloma, and squamous cell carcinoma. Macrophages containing these materials were observed in the lamina propria mucosa and submucosa of the colorectum. There were differences in the molecular weight of the substances and their tumor incidences. However, with regard to their carcinogenicity, these sulfated polysaccharides were inferred to be similar to each other in their target organs and process of tumor development. Consequently, these sulfated polysaccharides may be one entity of carcinogenic sulfates.

(1985). Recent advances in research on bracken carcinogen and carcinogenicity of betel nut. Journal of Environmental Science and Health. Part C: Environmental Carcinogenesis Reviews: Vol. 3, No. 2, pp. 145-187.

The chromosomes were investigated in the subline of the Yoshida sarcoma resistant to Nitrogen Mustard N-oxide, by way of comparison with those of the original stock line. The evidence presented indicates that the resistant character is not associated with the chromosome pattern of the tumor cells. Both the original stock tumor and its subline which is resistant to the drug are conditioned by similar chromosomal situations.

The carcinogenic activity of petasitenine, a new pyrrolizidine alkaloid isolated from young flower stalk of Petasites japonicus, was studied in ACI rats. All rats that had received a 0.05% solution of petasitenine in drinking water died or were killed in moribund condition 72 days after the start of experiment. They showed necrosis, hemorrhage, and remarkable proliferation of the bile ducts in the liver. In another group that had received a 0.01% solution, 8 of 10 animals surviving beyond 160 days developed tumors in the liver, i.e., hemangioendothelial sarcomas in 5 rats and liver cell adenomas in 5 rats, 2 of which simultaneously developed hemangioendothelial sarcomas. No tumors were observed in the livers of the control animals.

We attempted to induce neurological disorders in mice by a single administration of various doses of ptaquiloside (PT) within 24 h after birth. Animals which survived for a long period after treatment showed a reduction in body weight, but did not develop any gait disturbance. On the other hand, in treated animals which died before beginning to walk, karyorrhexis in the external granular layer of the cerebellum and karyorrhexis and rosette formation in the neuroblastic layer of the retina were present. In addition, treated animals showed karyorrhexis and great reduction in the number of the cells in the thymus, suggesting cytotoxic and cytolytic effects of alkylating agents on lymphocytes in this organ.