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Fucoxanthin-containing oil extracted from microalga, Chaetoseros sp., was subjected to genotoxicity studies, the bacterial reverse mutation test and the micronucleus test in mice. The number of revertant colonies in fucoxanthin oil-treated plates of all strains tested was less than twice the number of colonies in the negative control, regardless of the presence of the metabolic activator in the bacterial reverse mutation test. In the micronucleus test, 500, 1,000, 2,000 mg/kg body weight of fucoxanthin oil was administered orally to mice. There was no significant increase in micronucleus frequency in bone marrow cells. These results suggest that fucoxanthin oil does not exhibit genotoxicity.

Cefmatilen hydrochloride hydrate (S-1090), a new non-ester type of orally active cephem antibiotic synthesized in Shionogi Research Laboratories, was evaluated for its genotoxic potential using three assay systems. In a reverse mutation test with bacteria of Salmonella typhimurium TA100, TA1535, TA98, and TA1537, and Escherichia coli WP2uvrA using the preincubation method, the number of revertant colonies in the S-1090 treated plates was almost equal to that in the negative control plates in all strains with and without metabolic activation system with S9 mix (maximum dose, 100 micrograms/plate in TA98). In a chromosomal aberration test with cultured Chinese hamster lung cells (CHL/IU), S-1090 did not induce structural chromosome aberrations or polyploid cells either in the absence or presence of S9 mix up to the 50% growth inhibition doses. The potential of inducing clastogenicity and/or disruption of mitotic apparatus in vivo by S-1090 was evaluated by a micronucleus test with bone marrow cells of male Jc1:ICR mice. S-1090 suspended in 0.5% aqueous methylcellulose was administered by oral gavage up to 2000 mg/kg/day in single and double dosing groups. No induction of micronucleated polychromatic erythrocytes was observed 24 hr after the last dosing in each group. As all three genotoxicity tests showed negative responses, S-1090 is thought to have no genotoxic potential.

Cancer is a common life-threatening disease. Prevention and therapy of the disease are the desire of everybody. This paper summarizes our attempt to the tough challenge. Chronologically we began the study of carcinogenesis, and then turned to the research of anticancer agents. Identification of food mutagens was extensively studied. Once they were identified, the mechanism of nucleic acid modifications by these mutagens had been studied. The modification study gave information on the nucleic acid modification by mitomycin and bleomycin. The structure-activity relationship study of phorbol esters and teleocidines whose tumor promotion is epigenetic, was extensively studied. On the other hand, retinoic acid, a vitamin A metabolite, suppresses the epigenetic tumor promotion. This suggests that an epigenetically active compound rather than a cytotoxic anticancer agent can be used for tumor suppression. In the retinoid research, we found a number of characteristic new active substances which may be of therapeutic use: some of them are in the clinical trial stages in the field of dermatology and cancer. During the chemical study of retinoids, we encountered the retinoic acid receptor, coded by the retinoic acid receptor (RAR) gene which had just reported. Further retinoid research yielded retinoids antagonists, and then RXR(retinoic acid-X-receptor)-agonists and RXR-antagonists. These ligands have a big potential in the therapy of diabetes and obesity.

Nitrosamines are environmental carcinogens, and their relevance to human cancer is highly suspected. Dialkylnitrosamines require activation through metabolizing enzymes before they become ultimate electrophilic active species. This review summarizes two model systems for metabolic oxidation of dialkylnitrosamines. One system utilizes porphyrin and oxidant as a model for shunt pathway in the metabolizing pathway of cytochrome P450, and the other one utilizes Fenton reagent. Porphyrin and oxidant activated nitrosodialkylamines into direct acting mutagen by releasing aldehydes. During the process the alkylating activity was observed and alcohols are formed from the alkylation of water. Fenton reagent, consisting of iron salt and hydrogen peroxide supplemented with copper salt, activated dialkylnitrosamines into mutagens of a novel type containing an oxadiazine ring as their proposed structures. These works with model systems open a new aspect into the elucidation of the mechanism of xenobiotic metabolism.

The fact that hemin can inhibit the mutagenic activity of compounds bearing polycyclic structures is ascribable to the ability of the porphyrin structure to complex with the planar surface of the mutagens. The elucidation of this mechanism has led to the discovery of copper phthalocyanine trisulfonate (cpt) as an efficient ligand to trap polycyclic compounds on polymeric supports that bear cpt through covalent bond linkages. In blue cotton, the support for cpt is cotton, in blue rayon, it is amorphous rayon, and in blue chitin it is poly-N-acetylglucosamine. Using these blue materials, we have successfully isolated mutagens of polycyclic structures, e.g., heterocyclic amines, from environmental complex mixtures such as food, urine, feces, and river water. Preparation and properties of these adsorbents are described. Chlorophyllin linked to Sepharose and chitosan is also described. The use of these green materials is discussed.

The mutagenic potential of gadobenate dimeglumine formulation (E7155) was studied by the chromosome aberration test in cultured human lymphocytes. Human lymphocytes were exposed to E7155 at 0.078-10 mM both in the presence and absence of S9 mix derived from rat livers. Three dose levels (2.5-10 mM) were selected for the metaphase analysis. E7155 induced no increase in the incidence of aberrant cells or polyploid cells in any treatments both in the presence and absence of metabolic activation. Thus, it is concluded that E7155 has shown no evidence of clastogenic or polyploidy-inducing activity under these experimental conditions.

The ability of gadobenate dimeglumine formulation (E7155) to cause gene mutations was assessed in five strains of Salmonella typhimurium (TA100, TA1535, TA98, TA1538, and TA1537) and a strain of Escherichia coli (CM891; WP2, uvrA-, pKM101) using the Ames test (agar plate assay). The results suggest that E7155 is non-mutagenic towards these bacterial tester strains.

The purpose of this study was to investigate the influence of 3,3-dimethyl-1-phenyltriazene (DMPT) on development of craniofacial structures in mouse fetus. (1) Pregnant C57BL/6 mice were treated with 30 mg/kg DMPT injection on days 10.5 approximately 13.5 of gestation. The fetuses were analyzed on day 15.0. The incidence of micrognathia was formed 100% in the treated group on days 10.5 and 11.0, and then decreased remarkably after day 11.5. This result suggested that the critical period of micrognathic development is days 10.5 approximately 11.0. (2) The fetuses, injected 30 mg/kg DMPT on day 10.5, were sacrificed on days 11.0 approximately 18.0. Their heads were used for the following histomorphological analyses: 1. clearing and Alcian blue-alizarin red double staining and 2. lateral graphic reconstruction using serial frontal sections. Dysmorphology of the anterior portion of Meckel's and nasal septal cartilage became evident after day 13.0, however, nasal capsule cartilage was hardly affected. It was concluded that hypoplastic Meckel's cartilage, caused by the administration of DMPT, induced mandibular dysmorphogenesis.

Newly synthesized dinitrobenzo[a]pyrenes and 6-aza analogues of 1- and 3-nitrobenzo[a]pyrenes showed strong mutagenic activity in Salmonella assays (TA98 and TA98NR). Nitroreduction is essential for metabolic activation of nitroarene. The structure activity relationships of mono-, di- and trinitrophenanthrene were studied. Electrochemical ease of nitroreduction and dihedral angles of nitro substituents to aromatic rings is found to be important factor to determine their mutagenic potency. Nitroarene is oxidatively metabolized to form hydroxylated and nitrosubstituted derivatives and the same oxidative products were obtained by the reaction of nitroarene with chemically generated superoxide anion radical, suggesting the participation of superoxide in metabolic oxidation of nitroarene. Catalytic activity of nitroarene as a mediator in the reductive activation of molecular oxygen was also evaluated by using potential step chronocoulometry method. The potential relevence of toxicity caused by redox cycling could be solved by using this method.

We have already reported that a combination of TNF-alpha and immunogenic variant was effective for immunotherapy of nonimmunogenic tumor. Immunogenic variants (A2 and A7) were obtained from nonimmunogenic fibrosarcoma (parent cell: 1767-3) by mutagen treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). In this study, we studied about the possibility of TNF-alpha gene immunotherapy for nonimmunogenic tumor. We established two types of TNF-alpha producing cell lines. One is TNF-alpha producing nonimmunogenic variant (1767 TR 2), and another is TNF-alpha producing immunogenic variant (A7 TR3). We compared them about the ability of producing specific immunity against parent tumor. TNF-alpha producing immunogenic variant (A7TR3) could induce strong specific immunity to parental cell compared to TNF-alpha producing nonimmunogenic variant (1767TR2). Immunogenicity of tumor is very important when we want to perform TNF-alpha gene immunotherapy against cancer.

1. The reverse mutation test was carried out on suplatast tosilate (IPD-1151T) at dose range of 50-5000 micrograms/plate using Salmonella typhimurium strains TA100, TA1535, TA98 TA1538 and TA1537, and Escherichia coli strains WP2, WP2uvrA. In all tester strains no significant differences were observed in the number of revertant colonies as compared with solvent control in the absence or presence of mammalian metabolic activation system. 2. The chromosomal aberration test on IPD-1151T was carried out using cultured Chinese hamster lung cells (CHL). The cells were treated with IPD-1151T at the doses of 125, 250 and 500 micrograms/ml without S9 Mix and at the doses of 1250, 2500 and 5000 micrograms/ml with S9 Mix. The incidence of structural- and numeral-aberration was 0-4% in the absence or presence of mammalian metabolic activation system, no significant increases were observed in the incidence of chromosomal aberrations. 3. The micronucleus test using BDF1 male mice was conducted in order to evaluate the in vivo mutagenicity of IPD-1151T. IPD-1151T was orally administered at doses of 625, 1250, 2500 and 5000 mg/kg, with a sampling time of 24 hr. The frequency of polychromatic erythrocytes with micronuclei (MNPCE) was 0.23% in the lowest dose (625mg/kg) of IPD-1151T, but the frequency of MNPCE was 0.03-0.13% in the groups treated with 1250-5000 mg/kg of IPD-1151T and no significant increases were observed with dose dependence. The results indicated that IPD-1151T was negative, even in the assessment standard using our background data. 4. The present study indicates that IPD-1151T has no in vitro and in vivo mutagenic potential.

N4-Aminocytidine is strongly mutagenic towards E. coli, S. typhimurium, B. subtilis and coliphages phi X174 and M13mp2. It also causes mutations in mammalian cell lines and somatic cell mutations in D. melanogaster. The sequence analysis of deoxyribonucleic acid (DNA) from mutated phages revealed that N4-aminocytidine induces both adenine-thymine (AT) to guanine-cytosine (GC) and GC to AT transitions. No transversions are detectable. When E. coli and the mammalian cells were cultured in the presence of [3H]-N4-aminocytidine, [3H]-N4-aminodeoxycytidine was found in their DNA. It is likely that N4-aminocytidine is metabolized within the cells into N4-aminodeoxy-cytidine 5'-triphosphate (dCamTP), which is then incorporated into DNA, thereby causing base-pair transitions. To prove this hypothesis, we studied the incorporation of dCamTP into polynucleotides in the in vitro DNA synthesis catalyzed by E. coli DNA polymerase I large fragment (Klenow enzyme) and DNA polymerase alpha from a mouse cell line. Both polymerases catalyze incorporation of dCamTP into DNA efficiently in place of dCTP opposite guanine, and less efficiently, but to a significant extent, in place of dTTP opposite adenine. These observations prove the erroneous nature of dCamTP as a substrate for DNA synthesis. DNA containing N4-aminocytosine was prepared by the incorporation of dCamTP into single-stranded phage DNA annealed to complementary oligonucleotides. The DNA was transfected to E. coli cells. The analysis of progeny phages indicates that N4-aminocytosine residue in DNA causes A to G or G to A mutation in the position opposite to the site where N4-aminocytosine should be incorporated.

Recent development in toxicological study of styrene is summarized from the viewpoint of occupational health. The topics discussed are: 1) physico-chemical properties, 2) industrial use, work place environments and exposure control, 3) metabolism and biological monitoring of exposure, 4) general toxicity with special reference to dose-effect/response relationship in humans, and 5) in vitro and in vivo mutagenicity, mammalian teratogenicity and human/subhuman carcinogenicity. With 137 references.

1. Whether NK 631 is antigenic to guinea pigs and rabbits was studied by the methods of active and passive anaphylactic shock tests, Schultz-Dale reaction, passive cutaneous anaphylaxis, Ouchterlony, tanned red cell haemagglutination test and test according to the U.S. Appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics. However, none of the tests proved NK 631 to be antigenic. 2. The immunosuppressive effect of NK 631 was studied by delayed hypersensitivity to picryl chloride in normal and L-1210 tumor bearing mice. Therapeutic dosis of NK 631 was no immunosuppressed but toxic dosis of NK 631 was slightly decreased in ear thickness of delayed hypersensitivity. 3. The acute irritative effect of NK 631 and of bleomycin was studied by single instillation to the rabbit eye mucous membrane with 0.1 ml of either of 10, 33 and 100 mg/ml solution of the drugs in physiological saline. The irritative effect of NK 631 on the eye mucous membrane at each concentration was slightly severe than that of bleomycin at the same concentration. However, the manifestations were only mild to moderate dilatation of the conjunctival and nictating membrane blood vessels and eye mucous, and recovered or were mitigated 48 hours after the instillation. No severe changes such as corneal opacity, corneal desquamation, swelling and deaquamation of the conjunctival and nictating membrane were observed. The histopathological examination revealed no striking changes. 4. Mutagenicity of NK 631 and of bleomycin on Salmonella typhimurium strain TA 100 and TA 98 was studied. It was definitely shown that neither NK 631 nor bleomycin exerted any mutagenic action on either test strains.

The DNA-damaging activities of organic rubber additives such as rubber vulcanizing agents, vulcanization accelerators and rubber anti-oxidants were investigated by the rec-assay using spores of Bacillus subtilis strains H 17 and M 45. For metabolic activation, 9,000 X g supernatant solutions of the liver homogenate of Sprague-Dawley male rats previously treated with aroclor 1,254 were used. Spore rec-assays were carried out at the dose of 1 mg/disk, and the ratio of inhibition zones for M 45 to that for H 17 was calculated. Samples showing a ratio of more than 1.2 were judged positive. In order to know the DNA-damaging capacity of positive samples, the dose-response curves were prepared by carrying out the assays at various doses, and minimal inhibition concentration (MIC) for H 17 and M 45 was obtained from these curves by extrapolation. Then indices of DNA damagenicity were calculated through division of the MIC obtained with H 17 by that with M 45. The 0.005 micrograms/disk of mitomycin C and at 4 micrograms/disk of Trp-P1 were used as positive control, and the 50 micrograms/disk of kanamycin as negative control. The results obtained are as follows: Among 20 tested samples, p-quinone dioxime, bis-morpholine disulfide used as rubber vulcanizing agents and hexamethylenetetramine, zinc butylxanthate used as vulcanization accelerators gave positive results. It was considered that the action of hexamethylenetetramine against DNA was due to the electrophilic state of this material. Furthermore, we supposed that DNA-damaging activity of p-quinone dioxime was concerned with free hydroxyl groups of this compound.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenic activity of miporamicin (MPM), a new macrolide antibiotic for animal use, was examined using the reversion test with bacteria, the chromosomal aberration test with mammalian cells in culture and the micronucleus test with rodents. In the reversion test, MPM exhibited severe growth inhibition effect on the test bacteria but caused no increase of revertant colonies over the baseline levels, alone or in combination with S 9 mixture. In the chromosome aberration test, MPM induced a medium grade increase of chromosome aberrations at high concentrations, but induced no increase of polyploid cells over the control level. In the micronucleus test, MPM had no effect on induction of micronucleated polychromatic erythrocyte even at the 1/2 LD50 dose. From these results, we concluded that MPM has no effect on the induction of point mutations but has a weak clastogenicity which is detectable only by in vitro tests.

Food has been considered an important factor for the genesis of cancer in man, as important as cigarette smoking. Diet influences the incidence of human cancer in many ways, directly and indirectly. Various kinds of carcinogens such as polynuclear aromatic hydrocarbons, N-nitro compounds and mycotoxins have been reported to be present in various foods. During the last decade, a new series of heterocyclic amines has been isolated as potent mutagens and later shown to be potent carcinogens in animals. Among them, carcinogenic tryptophan pyrolysates have been investigated from various points of view and useful pieces of information about them have been collected. Now, it is a matter of urgency to evaluate the effects of these carcinogens on humans. From this aspect, this review describes the information about carcinogenic tryptophan pyrolysates which has been collected and also future problems, especially those the hygienist will have to solve.

The microbial mutation test developed by Ames has been revealed that many chemical carcinogens, which had been considered non-mutagenic, are actually mutagens and that a number of mutagens, the carcinogenicity of which has not yet been investigated, are carcinogens. The method is useful, in the chemical industry, for screening chemicals for carcinogenic potential because of its rapidity and economic return. The mutagenic activity of hundreds of chemicals has been investigated by this Ames test and a close relationship between mutagenicity and carcinogenicity has been demonstrated. It is considered that the application of this screening test is useful for prevention of occupational cancer in the chemical industry. In this paper the results of this test for industrial chemicals and the future problems are reviewed.

The relation between the mutagenic activities and chemical structure of phenanthridinium derivatives were tested by using Salmonella typhimurium strain TA 98 and yeast Saccharomyces cerevisiae. The 3,8-diamino analog and amino-azido isomers caused frameshift type mutation in Salmonella. However, mutagenicity was severely reduced for the diazido analog, and mutagenic activities of monoamino and monoazido analogs were minimal. The deaminated analog was not mutagenic. Diamino analog and two amino-azido isomers induced mitochondrial mutation of yeast in both resting and growing conditions. Two monoamino and deaminated analogs were mutagenic only in growing yeast but not in resting cells. Two monoazido and diazido analogs were less mutagenic even in the growing conditions.

The major causes of cancer in the developed countries are now thought to be environmental or man-made factors. Because most carcinogens are also mutagens, the detection and identification of muta/carcinogens to humans seem to be very important in the environmental sciences. We describe here, i) in vitro and in vivo short-term assays for muta/carcinogens in the environment, ii) possible method for monitoring human exposure to muta/carcinogens, and iii) some trials for estimating human risk for the development of cancers due to environmental mutagens.

Acute toxicity, eye irritation, primary skin irritation, skin sensitization, phototoxicity, photosensitization and mutagenicity of sophorolipid derivatives were studied in rats, mice, rabbits, guinea pigs and Salmonella typhimurium strains. The acute oral toxicity of sophorolipid (SL) which Torulopsis bombicola produces, and its derivatives (PSL, Ethyl-SL and Oleyl-SL) were shown to be very low. The LD50 values of PSL ranged from 10 g/kg to 16 g/kg on oral administration in rats and mice, and from 5.8 g/kg to 6.6 g/kg on subcutaneous administration in mice. The oral LD50 values of Ethyl-SL and Oleyl-SL were estimated to be greater than 15 g/kg and that of SL was 12.5 g/kg. In eye irritation study, PSL failed to produce any reactions at 50% concentration even when the rabbit eye was not subsequently washed. SL, Ethyl-SL, Oleyl-SL and Tween 20 were "no irritant" or "slight irritant" to the rabbit eye at 20% concentration. PSL showed no irritancy to both the intact and abraded guinea pig skin at 50% concentration. And in other examinations, it was also indicated that PSL had no potentials of skin sensitization, phototoxicity and photosensitization in guinea pigs and had no potentials of mutagenicity in Salmonella typhimurium TA98 and TA100.

Today industrial use of benzidine is restricted in many countries. However, little attention is paid to those substances which may decompose themselves in the body and release benzidine or benzidine-like substances. I investigated the mutagenicity of urinary ingredients of rats to which benzidine and three kinds of azo dyes were separately administered through the alimentary tract. The azo dyes were Direct Black EX(EX), Direct Green BK(BK), and Direct Bordeaux BK(BK), all having 4,4'-diazobiphenyl group in each structure. The mutagenicity of the urine extract with ether was tested on Salmonella typhimurium TA 98 and TA 100. Urinary metabolites of benzidine showed stronger mutagenicity than benzidine itself on both TA 98 and TA 100 in the presence of S9 mix. EX itself showed mutagenicity only on TA 98, whereas B and BK were nonmutagens. Nevertheless, the urine extract of each azo dye showed strong mutagenicity of the same pattern as benzidine. As a result it is suggested that benzidine might be released in the intestine of experimental animals after the administration of each azo dye. Mutagenic activity of urine sample is important and full of suggestions from the viewpoint of carcinogenicity of aromatic amines.

Cadmium has been thought to be carcinogenic for these ten years. The present author reviewed 98 papers on its carcinogenicity. Ten papers describing epidemiological studies on cadmium workers, re-evaluated by the present author, do not derive a solid conclusion that cadmium is carcinogenic. However, there still exists a certain probability that cadmium is a weak carcinogenic substance in the human, because of some data on chromosomal aberrations in cadmium workers, tumorigenesis at the site of cadmium injection in animals, and Leydig cell tumor formation in animals given subcutaneous injections of cadmium.

Mutagenicity of MT-141, a new cephamycin, was evaluated by in vitro and in vivo assays. MT-141 did not induce mutations of the test strains, Escherichia coli WP2 (uvr A) and Salmonella typhimurium TA1535, TA1537, TA1538, TA100 and TA98, with and without metabolic activation in vitro. In bone marrow micronucleus assay with male mice, MT-141 showed no induction of micronucleated polychromatic erythrocyte at 6 hours and 30 hours after administration. In addition MT-141 was found not to cause any dominant lethal effects on male mice for 8 weeks after administration.

Microbial backward mutation test, Ames Salmonella/microsome plate assay, on six bacterial strains (Salmonella typhimurium TA 98, 100, 1535, 1537, 1538 and E. coli WP 2uvrA) and micronucleus test in mice were carried out to detect mutagenic activity of mequitazine. Mequitazine caused no increases of revertants at doses from 1 to 1000 microgram/plate in every bacterial strains irrespective of metabolic activation. Similarly, mequitazine induced no significant increases of micronucleated polychromatic erythrocytes in mice over the control level at doses from 0.12 (clinical dose) to 48 mg/kg (approx. LD 50). From above results, we concluded that mequitazine has no mutagenic activity per se.