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T Sugimura

Publications and source records attributed to T Sugimura.

At least 127 records · Page 7Linked to original sources
PubMed1998

Targeting strategy for gene delivery to carcinoembryonic antigen-producing cancer cells by retrovirus displaying a single-chain variable fragment antibody.

Cancer-specific antigens are promising targets for the specific delivery of certain drugs or genes to cancer cells in cancer therapy. Carcinoembryonic antigen (CEA) is one of the cancer-associated antigens predominantly detected in the gastrointestinal cancer of the colon and stomach. Targeting strategies for CEA-producing cancer cells have been thoroughly developed mainly by the production of monoclonal antibodies to CEA and further single-chain variable fragment (scFv) antibodies. Here, we have generated Moloney murine leukemia virus-derived retroviral vectors co-displaying an anti-CEA scFv-envelope chimeric protein and an unmodified envelope protein to deliver a gene for herpes simplex virus thymidine kinase (HSV-tk) or Escherichia coli beta-galactosidase. The harvested viruses successfully incorporated the chimeric envelope protein as well as the unmodified envelope into the viral particles, and specifically bound to and infected human CEA-producing cancer cells via recognition of CEA, depending on the CEA-producing phenotype of the target cells. These results may have significant implications for the use of scFv directed against tumor-specific antigens for targeting specific antigen-producing cancer cells, a potential step toward in vivo cancer therapy.

3T3 Cells↗
PubMed1998

A novel monoclonal antibody permitting recognition of NKT cells in various mouse strains.

By immunizing mouse lymphoma cell line tMK-2U derived from intermediate TCR cells of BALB/c nude mouse, U5A2-13 monoclonal antibody (mAb, a rat IgG2a) was established. U5A2-13 antigen (Ag) was expressed on around 65% of TCRint cells in the liver of the various mouse strains including both NK1.1- and NK1.1+ mouse strains, while NK1.1 Ag was expressed only in NK1.1+ C57BL/6 mouse strain. Among CD3+ cells, 26.3% cells co-expressed U5A2-13 Ag and NK1.1+ Ag, while small proportions of the CD3+ cells were U5A2-13+NK1.1- (9.2%) or U5A2-13-NK1.1+ (4.4%). Among NK1.1+ cells, 54.9% cells co-expressed CD3 and U5A2-13 Ag, while some proportions of the cells were U5A2-13+CD3- (19.4%) or U5A2-13-CD3+ (9.8%). It was found that approximately 85% of NK1.1+CD3+ cells coexpressed U5A2-13 Ag. U5A2-13 Ag with low fluorescence intensity was also expressed on 55% of NK1.1+CD3-NK cells. U5A2-13 Ag immunoprecipitated from tMK-2U cells consisted of three proteins, which were 65 kDa, 33 kDa and 32 kDa under both reducing and non-reducing conditions and these were apparently different from NK 1.1 Ag. These results indicated that U5A2-13 mAb was able to define a similar population to NK1.1+CD3+T cells and to 55% of NK1.1+CD3-NK cells in various strains, through recognizing a different molecule from NK1.1 Ag.

Animals↗
PubMed1998

Beta-catenin is frequently mutated and demonstrates altered cellular location in azoxymethane-induced rat colon tumors.

Beta-Catenin is a key regulator of the cadherin-mediated cell-cell adhesion system and an important element in the Wnt signal transduction pathway. Stabilization and accumulation of cytoplasmic beta-catenin, which result from mutations in either the adenomatous polyposis coli or beta-catenin genes, are causatively associated with colon carcinogenesis. In the present study, we examined the expression of beta-catenin in rat colon tumors induced by azoxymethane in comparison with adjacent normal colon mucosa by immunostaining and immunoblotting. Cytoplasmic and nuclear immunostaining was pronounced in all colon adenoma and carcinoma tissues, whereas antibody binding was limited to membranes at the intercellular borders in normal colon epithelial cells. Increase of the free beta-catenin fraction in tumor cells was also indicated by immunoblot analysis of fractionated tissue lysates. Investigation of mutations in the glycogen synthase kinase-3beta phosphorylation consensus motif of the beta-catenin gene by PCR-single strand conformation polymorphism methods and direct sequencing revealed eight mutations in six of the eight colon carcinomas, and seven of these were shown to be G:C to A:T transitions, with five being CTGGA to CTGAA. Such frequent mutations of the beta-catenin gene in azoxymethane-induced rat colon tumors suggest that consequent alterations in the stability and localization of the protein may play an important role in this colon carcinogenesis model.

Adenocarcinoma↗
PubMed1998

Generation of polymorphic markers tightly linked to the thymus enlargement loci by phenotype-directed representational difference analysis.

To obtain genetic markers linked to a specific genetic locus, genomic subtraction with a DNA pool of backcross or F2 intercross animals with a specific genotype at the locus is known to be effective. To determine whether the pooling strategy is also effective for isolation of genetic markers linked to a quantitative phenotype that can potentially be controlled by multiple genetic loci, we tested the ability of representational difference analysis (RDA) to isolate genetic markers linked to the thymus enlargement observed in the BUF/Mna (BUF) rat. This is known to be controlled by single major and minor genes, Ten1 and Ten2, on Chromosomes (Chrs) 1 and 13, respectively, both of which have dose effects on the normal WKY/Ncj (WKY) allele. DNA from an inbred WKY rat was used as the tester, and the driver was prepared from a DNA pool of 12 (WKY x BUF)F1 x BUF backcross rats with high thymus ratios (thymus weight/body weight), expected to have dominance of the BUF allele in the responsible loci. By two RDA series with the restriction enzymes BglII and BamHI, respectively, 28 polymorphic markers were isolated, and 8 of them were shown to be linked to Ten1, and one to Ten2. One of the 8 markers linked to Ten1 demonstrated no recombination in 18 rats with high thymus ratios. RDA with a DNA pool based on a quantitative phenotype (phenotype-directed RDA) can thus be considered an efficient approach for direct isolation of polymorphic markers linked to a quantitative trait.

Animals↗
PubMed1998

Isolation of 48 genetic markers appropriate for high throughput genotyping of inbred rat strains by B1 repetitive sequence-representational difference analysis.

Mapping of genetic suppressors, modifiers, and quantitative trait loci (QTLs) requires genetic markers that can be efficiently and inexpensively genotyped for a large number of individuals. To isolate rat genetic markers suitable for this purpose, representational difference analysis (RDA) was performed with amplicons prepared by PCR with the B1 repetitive sequence used as the primer (B1-amplicons). In total, 48 polymorphic DNA fragments were isolated by five series of RDA, subtracting the B1-amplicons prepared from an ACI/N (ACI) rat from those prepared from BUF/Nac (BUF), and vice versa. All the polymorphic fragments detected "presence-or-absence" polymorphisms with B1-amplicons prepared from ACI, BUF, and their F2 progeny, and each fragment was linkage mapped. Dot-blotting amplicons onto filters at a high density and hybridization of the filters with these B1-RDA markers made it possible to genotype a large number of rats simultaneously for multiple loci. These B1-RDA markers were polymorphic between two given inbred strains of rat at frequencies between 30% and 70%. This is the first report on the isolation of B1-RDA markers among inbred strains of rats.

Animals↗
PubMed1998

Noninvasive evaluation of myocardial ischemia in Kawasaki disease: comparison between dipyridamole stress thallium imaging and exercise stress testing.

The sensitivities of dipyridamole stress thallium 201 single photon emission computed tomography (SPECT) and treadmill exercise testing in the detection of myocardial ischemia were compared. Thirty-eight patients with Kawasaki disease and 11 age-matched controls participated in the study. Fifteen of the 38 patients with Kawasaki disease had marked coronary artery stenosis (> 75%) in at least one vessel. SPECT scans were obtained immediately after dipyridamole infusion and 4 hours later. The sensitivity of SPECT for detection of coronary stenosis was 80% (12/15), whereas that of treadmill exercise testing was only 33% (5/15) (p < 0.001). Although the sensitivity of SPECT significantly exceeded that of treadmill exercise testing among patients with coronary stenosis in only one vessel (p < 0.05), such benefits were not found for patients with stenosis in two or three vessels. These findings suggest that dipyridamole stress SPECT has a higher degree of sensitivity in the detection of myocardial ischemia than does treadmill exercise testing, especially for patients with single-vessel disease.

Child↗
PubMed1998

Mouse NK1.1+ cytotoxic T cells can be generated by IL-2 exposure from lymphocytes which express an intermediate level of T cell receptor.

NK-like T cells which express the NK1.1 molecule and CD3 (or TCR) of intermediate level (CD3int or TCRint cells) were recently demonstrated to be present in various immune organs, and to have NK-like cytotoxic activity against NK target cells. In this study, we investigated whether NK1.1- T cells could express NK1.1. We found that NK1.1+ TCRint cells were much more abundant in the liver (20%) than in the spleen (2%). When hepatic and splenic mononuclear cells (MNCs) were cultured either in the absence of IL-2 or in the presence of CD3/TCR cross-linking, the original NK1.1+ TCRint cells disappeared. However, when they were cultured in the presence of a high dose of IL-2 for 4 days, a new type of NK1.1+ T cell was formed to the extent of approximately 15-20%, and the liver and spleen contained similar percentages of this new type of NK1.1+ T cells. The phenotypes of the original and the new type of NK1.1+ T cells were clearly distinct. The freshly obtained NK1.1+ TCRint cells consisted of double-negative (DN) CD4-CD8- cells and single-positive (SP) CD4+ cells, whereas the new type of NK1.1+ T cells predominantly consisted of DN CD4-CD8- cells and SP CD8+ cells and expressed a high level of CD3 (CD3high or TCRhigh cells). When NK1.1- cells or IL-2 receptor beta-chain (IL-2Rbeta)- cells were isolated from the liver and spleen, and cultured in the presence of IL-2 for 4 days, NK1.1+ T cells were generated from NK1.1- cells, but not from IL-2Rbeta- cells. Our results suggested that the NK1.1- cells, but not IL-2Rbeta- cells, contained the precursor of IL-2-stimulated NK1.1+ TCRhigh cells. When purified NK1.1- IL-2Rbeta+ TCRint cells were cultured in the presence of IL-2 for 4 days, approximately 10% of the cells became NK1.1+ TCRhigh cells. Approximately 60% of the purified NK1.1+ TCRint cells lost NK1.1 expression. The IL-2-stimulated NK1.1+ TCRhigh cells that had arisen from NK1.1- TCRint cells exerted an NK cell-like cytotoxic activity similar to that of the original NK1.1+ T cells. Thus, NK1.1- TCRint cells could express NK1.1 and exert NK-like cytotoxic activity regardless of their origin. It appears that NK1.1+ TCRhigh cells can only be induced through an IL-2-stimulation pathway but not via CD3/TCR cross-linking.

Animals↗
PubMed1998

Coronary endothelial dysfunction after Kawasaki disease: evaluation by intracoronary injection of acetylcholine.

OBJECTIVES: This study sought to assess the endothelial function of long-term coronary artery lesions in patients with Kawasaki disease (KD). BACKGROUND: The vascular function of the coronary arteries in children with long-term KD remains uncertain. We report our findings of the vascular response of the coronary arteries to intracoronary injection of acetylcholine (ACh) in patients with KD. METHODS: A total of 35 patients (25 patients with KD and 10 control subjects) were examined using coronary angiography. Individual arteries were divided into four groups according to the type of the coronary artery lesion: group 1 consisted of 25 sites with regressed aneurysms. These aneurysms had developed in the acute stage but had subsequently regressed and demonstrated normal findings on the follow-up coronary angiogram. Group 2 consisted of 24 sites with persistent aneurysms. Group 3 involved 60 angiographically normal sites in the same patients as those in group 1 or 2. Group 4 consisted of 30 sites in control subjects who had congenital heart disease with normal coronary arteries. During coronary angiography we infused 15 microg of ACh chloride into the coronary artery. The lumen diameters were measured using a cine videodensitometric analyzer to study the distensibility of the coronary artery wall. RESULTS: The mean (+/-SD) change in diameter was an increase of 11.71+/-12.34% in group 3 (coronary arteries without lesions in patients with KD) and 12.21+/-9.71% in the control group, demonstrating marked vasodilation in both groups. In contrast, the changes in the regressed aneurysms of group 1 and in the persistent aneurysms of group 2 were -2.65+/-12.12% and -0.08+/-6.51%, respectively, demonstrating no change or mild vasoconstriction. The change in groups 1 and 2 was significantly less than that in group 3 or in the control group. Group 3 showed no significant difference from the control group. CONCLUSIONS: These findings suggest that long-term coronary artery lesions, even after aneurysm regression, may have impaired endothelial function. A long-term follow-up study for those patients is essential.

Acetylcholine↗
PubMed1998

Chemical synthesis of a novel aromatic amine mutagen isolated from water of the Nishitakase River in Kyoto and a possible route of its formation.

Among five mutagenic compounds isolated from water samples, taken at sites below the sewage plants of the Nishitakase River in Kyoto, Japan, the structure of compound I has been determined to be 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1). Since this novel aromatic amine mutagen has characteristic substituents in its molecule, it is postulated that the azo dye, 2-[(2-bromo-4, 6-dinitrophenyl)azo]-4-methoxy-5-[bis(2-methoxyethyl)amino]acetoanili de (AZO DYE-1), used as an industrial material, is converted to the corresponding 2-phenylbenzotriazole derivative with a reducing reagent and subsequently to PBTA-1 by chlorination. In fact, AZO DYE-1 changed to the dechlorinated derivative of PBTA-1 (deClPBTA-1) on treatment with sodium hydrosulfite, and this reacted with sodium hypochlorite to produce PBTA-1. Moreover, the presence of deClPBTA-1 was confirmed in a river water sample, along with PBTA-1. PBTA-1 showed potent mutagenic activities in Salmonella typhimurium TA98 and YG1024, inducing 88 000 and 3 000 000 revertants, respectively, per microg, with S9 mix. deClPBTA-1 was also mutagenic, but less potent. From these observations, it is suggested that PBTA-1 is produced from AZO DYE-1 through deClPBTA-1, during industrial processes at dyeing factories and the treatment of wastewater at sewage plants.

Japan↗
PubMed1998

Identification of a 2-phenylbenzotriazole (PBTA)-type mutagen, PBTA-2, in water from the Nishitakase River in Kyoto.

We previously isolated five mutagens, compounds I-V, in blue rayon-adsorbed materials from the Nishitakase River in Kyoto. The chemical structure of compound I, a major mutagen that accounted for 21% of the total mutagenicity, was determined to be 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl]-5-am ino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1). Compound II was also a major mutagen and accounted for 17% of the total mutagenicity. In this study, a large quantity (1.2 mg) of compound II was isolated from adsorbate to 27 kg of blue cotton, and its UV, mass, and 1H NMR spectra were analyzed. On the basis of the spectral data, compound II was deduced to be the PBTA-1 analogue 2-[2-(acetylamino)-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphenyl]-5- amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2). As with PBTA-1, PBTA-2 was synthesized from an azo dye by reduction and chlorination. Since all of the spectra of PBTA-2 coincided with those of compound II obtained from river water, compound II was concluded to be PBTA-2. PBTA-2 is a newly identified potent mutagen, which induces 93 000 and 3 200 000 revertants of Salmonella typhimurium TA98 and YG1024 per microgram, respectively, in the presence of S9 mix. Like PBTA-1, PBTA-2 may also be produced from an azo dye during industrial processes in dyeing factories and treatment at sewage plants.

Azo Compounds↗
PubMed1998

Elevated serum level of thioredoxin in patients with hepatocellular carcinoma.

Thioredoxin (TRX) is known to contain an active site with a redox-active disulfide and has various biological activities. The objective of the present study was to investigate whether circulating TRX levels are elevated in patients with chronic hepatitis (CH) or liver cirrhosis (LC) and hepatocellular carcinoma (HCC). An anti-TRX monoclonal antibody and polyclonal antibodies that specifically recognize TRX, were generated and used for the development of an ELISA system to measure TRX levels in human serum. The geometric mean and its 95% confidence interval of serum level of TRX in healthy volunteers was 81.75 ng/ml (74.60-89.59 ng/ml). The serum level of TRX in LC/CH patients without HCC was 80.87 ng/ml (69.66-93.88 ng/ml). The value was not statistically different from that in serum from normal volunteers (p=0.69). In contrast, the serum level of TRX in patients with HCC was 147.35 ng/ml (125.53-172.96 ng/ml), which was significantly higher when compared with the level in serum of normal volunteers (p<0.001) and in serum of LC/CH patients without HCC (p<0.001). In four patients with HCC, the initially high level of serum TRX (>150 ng/ml) decreased below 150 ng/ml after surgical removal of the tumor. The data reported herein revealed that patients with HCC had a significantly elevated serum level of TRX, suggesting that measurement of serum of TRX might be a useful clinical parameter when HCC is suspected.

Adult↗
PubMed1998

Suppressive effects of nimesulide, a selective inhibitor of cyclooxygenase-2, on azoxymethane-induced colon carcinogenesis in mice.

The effects of nimesulide, a selective inhibitor of cyclooxygenase-2 (COX-2) on azoxymethane (AOM)-induced colon carcinogenesis were investigated in mice. AOM at a dose of 10 mg/kg body wt was administered to male ICR mice once a week for 6 weeks. The animals were fed on AIN-76A powder diet containing nimesulide at doses of 200 or 400 p.p.m., starting the day before the first carcinogen treatment until the end of the experiment, at week 30. Administration of nimesulide reduced the incidence of colon carcinomas to 32 and 25% for the AOM + 200 and 400 p.p.m. nimesulide groups, respectively, compared with the AOM + basal diet group (50%). Multiplicities of colon carcinomas in the 200 and 400 p.p.m. nimesulide-treated groups were 0.70 +/- 0.28 and 0.35 +/- 0.11, respectively, being significantly smaller than the AOM alone value (1.79 +/- 0.47). The sizes of the colon carcinomas in the nimesulide-treated groups were also decreased. No significant influence on liver and lung tumor development was apparent. Thus, nimesulide exerted a suppressive effect on AOM-induced colon carcinogenesis in mice.

Animals↗
PubMed1998

Structural determination of a mutagenic aminophenylnorharman produced by the co-mutagen norharman with aniline.

Norharman (9H-pyrido[3,4-b]indole), widely distributed in our environment, including cigarette smoke and cooked foodstuffs, is not mutagenic to Salmonella strains, but becomes mutagenic to S.typhimurium TA98 and YG1024 with S9 mix in the presence of non-mutagenic aromatic amines such as aniline and o-toluidine. To elucidate the mechanisms of co-mutagenicity, we tried to isolate the mutagen(s) produced by a reaction between norharman and aniline with S9 mix. By HPLC purification, two mutagenic compounds (I and II), one (I) showing mutagenicity with and the other (II) without S9 mix, were isolated. The structure of compound I was deduced to be a coupled compound of norharman and aniline, 9-(4'-aminophenyl)-9H-pyrido[3,4-b]indole (aminophenylnorharman), by a variety of spectrometry techniques and this was confirmed by its chemical synthesis. The mutagenic activity of this novel heterocyclic amine was tested using the pre-incubation method and was found to induce 187,000 revertants in TA98 and 1,783,000 revertants in YG1024 per microg with S9 mix. Compound II was shown to be hydroxyaminophenylnorharman. Formation of the same DNA adducts was observed in YG1024 when aminophenylnorharman or a mixture of norharman plus aniline was incubated with S9 mix. The hydroxyamino derivative also yielded the same DNA adducts in YG1024. Thus, the appearance of mutagenicity by norharman with aniline in the presence of S9 mix suggests that the coupled mutagenic compound, aminophenylnorharman, is formed from norharman and aniline, then converted to the hydroxyamino derivative and forms DNA adducts to induce mutations in TA98 and YG1024.

Aniline Compounds↗
PubMed1998

Inhibition by 1'-acetoxychavicol acetate of lipopolysaccharide- and interferon-gamma-induced nitric oxide production through suppression of inducible nitric oxide synthase gene expression in RAW264 cells.

Although nitric oxide (NO) is an important biological mediator, excessive production in inflammation is thought to be a causative factor of cellular injury and cancer in the long term. In the present study the effects of 1'-acetoxychavicol acetate (ACA), which has anticarcinogenic properties, on NO production in murine macrophage cell line RAW264 cells stimulated with lipopolysaccharide or interferon-gamma were examined. ACA suppressed NO production dose dependently with an IC50 of 160 ng/ml (680 nM). The decrease in NO production was shown to parallel reduced expression of iNOS mRNA and protein. The influence of ACA on transcription factors, such as NF-kappaB, AP-1 and Stat1, which are involved in expression of the iNOS gene was assessed. ACA was found to suppress degradation of IkappaB, an NF-kappaB inhibitory factor, and consequently inhibit NF-kappaB activation. Activation of AP-1 and Stat1 was also blocked by ACA treatment. Thus we demonstrate that ACA exerts potent inhibitory effects on NO production, apparently mediated by modulation of activation of several transcription factors. This could contribute to the anticarcinogenic properties of ACA.

Animals↗
PubMed1998

Experimental chemical carcinogenesis in the stomach and colon.

Experimental chemical carcinogenesis in the digestive tract is reviewed, mainly on the basis of information obtained in the laboratories of the National Cancer Center Research Institute. It is generally accepted that cancer is the outcome of DNA damage, resulting in mutation, loss, amplification and recombination of genes. Gastric cancer is no exception. It was shown very early that cancer of the glandular stomach can be produced in rats by administration of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), a widely used mutagen. However, this depends on the genotype. Whereas the ACI rat is susceptible to MNNG, the Buffalo rat is resistant and this is a dominantly inherited trait. Genes responsible for the sensitivity to gastric cancer induction are at present under investigation by linkage analysis of rat genome markers. With regard to cancer in humans, our finding that cooked proteinaceous foods can give rise to a series of heterocyclic amines (HCAs) is of major significance. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), one of the most abundant, causes colon cancers in male rats, whereas in females it induces breast cancers. The colon cancers induced by PhIP feature a deletion of G as represented by 5-GGGA-3-->5-GGA-3 in the Apc gene, resulting in a truncated Apc molecule. Microsatellite mutations have also been found in PhIP-induced colon tumors, as in human hereditary non-polyposis colorectal cancer cases. Similarly to the case of gastric cancer production by MNNG, there is a genetic component and F344 rats are more susceptible to PhIP colon carcinogenesis than the ACI/N strain and the gene responsible is being sought. Since carcinogenesis proceeds with accumulation of genetic alteration, often involving genomic instability, exposure to any kind of carcinogenic substances, either xeno- or autobiotics, needs to be reduced as far as possible, taking account of inconvenience at the individual and socio-economical levels.

Adenomatous Polyposis Coli↗
PubMed1998

Effects of soybean isoflavones on cell growth and apoptosis of the human prostatic cancer cell line LNCaP.

BACKGROUND: Epidemiological studies have suggested that soybean isoflavones are associated with a lower risk of prostate cancer. However, the mechanisms of prostate cancer prevention by soybean isoflavones have yet to be fully clarified. METHODS: Two soybean isoflavones (genistein and daidzein) and their glucosides (genistin and daidzin) were tested for their effects on cell growth and apoptosis of the LNCaP human prostatic cancer cell line. RESULTS: Among these isoflavones, genistein was found to inhibit the growth of LNCaP most effectively, with an IC50 value of 40 microM. The inhibition of cell growth by genistein was accompanied by the suppression of DNA synthesis and the induction of apoptosis. Expression of prostate-specific antigen (PSA) in LNCaP was also significantly reduced by the treatment with genistein. CONCLUSIONS: The results suggest that genistein might primarily influence human prostate cancer development by reducing tumor growth.

Apoptosis↗
PubMed1998

DNA adduct level induced by 2-amino-3,4-dimethylimidazo[4,5-f]-quinoline in Big Blue mice does not correlate with mutagenicity.

In previous experiments we analyzed the mutant frequency (MF) and mutational types in various organs of lacI transgenic mice which were fed a diet containing 300 p.p.m. 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), a food-borne mutagen/carcinogen. To clarify the relationships between mutational type and adduct molecular species and between adduct level and MF we analyzed adducts in the same DNA samples. The DNA adduct in the liver, heart, colon, forestomach and bone marrow was determined by the modified intensification method of 32P-post-labeling at time points 1, 4 and 12 weeks. Only a single spot corresponding to N2-(deoxyguanosin-8-yl)MeIQ 5'-monophosphate was detected in DNA from all organs at all time points examined, with a recovery of 48%. The difference in mutation type between bone marrow and other organs detected in the previous experiment was not explained by adduct molecular species. At 4 and 12 weeks administration the adduct levels were highest in the liver and then heart, colon, forestomach and bone marrow in decreasing order, with values of 28.3, 8.4, 3.3, 1.3 and 0.4 molecule/10(7) nucleotides at 12 weeks. Based on our previously reported data, lacI MF was highest in the colon and those in the liver, bone marrow and forestomach were 10-60% of that of the colon; no increase in MF was detected in the heart, where no DNA replication is expected except for vascular endothelial cells. There was no direct relationship between MF and adduct level. The MF may be the product of adduct level and cell proliferation rate.

Animals↗