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T Sugimura

Publications and source records attributed to T Sugimura.

At least 235 records · Page 13Linked to original sources
PubMed1995

Specific 5'-GGGA-3'-->5'-GGA-3' mutation of the Apc gene in rat colon tumors induced by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine.

The APC gene plays a major role in human colon carcinogenesis. We determined the genomic structure of the rat Apc gene, and we analyzed mutations in colon tumors induced in F344 rats by 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), potent carcinogens contained in ordinary daily human food. Of eight PhIP-induced tumors, one tumor had two Apc mutations, two tumors had a mutation with loss of the normal allele, and one had a mutation. Two of the above five mutations were at nucleotide 1903, one at 2605, and two at 4237, all being a deletion of a guanine base at the 5'-GGGA-3' site and resulting in truncation of the APC protein. Of 13 IQ-induced tumors, 2 had an Apc mutation with loss of the normal allele. The two mutations were a missense mutation (T-->C) at nucleotide 1567 and a nonsense mutation (C-->T) at 2761. Alteration of the Apc gene was shown to play a more important role in PhIP-induced than in IQ-induced rat colon carcinogenesis. PhIP-induced tumors are characterized by their specific and unique mutation, which may be useful for mutational fingerprinting of human cancers.

Animals↗
PubMed1995

Mutation, loss of heterozygosity, and recombination of the p53 gene in mouse forestomach tumors induced by 2-amino-3,4-dimethylimidazo[4,5-f]quinoline.

2-Amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), a food mutagen, induces forestomach tumors in CDF1 mice. We established a polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis system to detect mutations in the mouse p53 gene exons 2-10, which encompass all five regions conserved among species, and a system to examine loss of heterozygosity (LOH) that uses newly identified polymorphisms between BALB/c and DBA mice, the parental strains of CDF1 mice. Four original forestomach tumors (one papilloma, two carcinomas, and one lymph-node metastasis) and four cell lines derived from four independent forestomach tumors were examined with the PCR-SSCP system and by polymorphism analysis. Of the four original tumors, the papilloma had a G-->A transition at the second position of codon 171, and one carcinoma had a G-->T transversion at the second position of codon 113 with loss of the wild-type allele, whereas the other two carcinomas had no detectable mutations. Of the four cell lines, two had a base substitution and LOH, and the other two had double mutations (a base substitution and a deletion). By amplification of the double mutations in a fragment, the two cell lines were shown to have four kinds of alleles, indicating induction of recombination within the p53 gene. Our results show that our PCR-SSCP analysis system is efficient for detecting p53 mutations in mouse genomic DNA and that alteration of the p53 gene plays a significant role in MeIQ-induced mouse forestomach carcinogenesis.

Animals↗
PubMed1995

Construction of a phylogenetic tree for inbred strains of rat by arbitrarily primed polymerase chain reaction (AP-PCR).

We constructed a tentative genealogic tree of 13 inbred rat strains using genetic markers identified by the AP-PCR (Arbitrarily Primed Polymerase Chain Reaction) technique, which consists of PCR amplification under low stringency conditions, with only one oligonucleotide as both forward and reverse primers. We obtained discrete-state genotypes of 264 loci, presumably covering the whole rat genome. Computational analysis of this panel allowed the construction of a genealogic tree representing the relations among the 13 strains. The accordance of the present results with available data on the histories of some of these strains validates the use of the AP-PCR technique for studies on phylogeny.

Animals↗
PubMed1995

Protein serine/threonine phosphatases as binding proteins for okadaic acid.

Recently, many potent inhibitors of protein serine/threonine phosphatases (PPs) have been found. Some of them have proven to be tumor promoters in mouse skin two-step carcinogenesis and rat liver medium-term tests. Among these inhibitors, okadaic acid (OA) selectively inhibits PP2A, and its use has therefore been proposed to facilitate analysis of biological roles of this phosphatase. OA shows bimodal effects on in vitro transformation and, in addition to such epigenetic changes, also induces marked genetic changes. OA treatment for more than 1 week flattened NIH 3T3 transformants irreversibly, with loss of the transfected genes. It is also known to induce diphtheria toxin-resistant mutations in Chinese hamster lung cells and sister chromatid exchanges (SCEs) in Chinese hamster ovary cells and human lymphocytes. To analyze roles of protein phosphatases in gene stability, we isolated OA-resistant mutants. They were proven to have a mutation in the PP2A alpha catalytic subunit, in which cysteine 269 had been substituted for glycine; and it was demonstrated that this region interacts with OA. The recombinant mutant protein was 4 approximately 9-fold more resistant to OA than the wild type. Although the OA resistant mutants of CHO cells expressed high levels of P-glycoprotein, inhibition of PP2A itself was suggested to lead to SCE induction. However, the number of molecular species of PP which are known to be sensitive to OA continues to increase, and we have isolated cDNA for a novel type of OA sensitive PP. Our studies indicate that the fact that the roles of PP2A cannot be elucidated using only OA is of crucial importance.

3T3 Cells↗
PubMed1995

A rapid method for detection of mutations in the lacI gene using PCR-single strand conformation polymorphism analysis: demonstration of its high sensitivity.

The lacI gene has been used as a target gene in various mutation assays. We modified single strand conformation polymorphism (SSCP) analysis by introducing restriction digestion to detect mutations in the gene rapidly, and determined the sensitivity of the method. The entire coding sequence and partial promoter region of the lacI gene were amplified by the polymerase chain reaction with [alpha-32P]dCTP in a 1247 base pair fragment, digested into eight restriction fragments, and analyzed by SSCP. The sensitivity of the method was assessed using 160 phages with lacI mutations, which were selected by assay of expression of beta-galactosidase after their infection into E. coli. Of the 160 mutants, 146 (91.3%) showed shifted bands in the first condition of SSCP analysis (without glycerol, 20 degrees C). The remaining 14 mutants were analyzed in a second condition (with 5% glycerol, 20 degrees C), and eight of them showed shifted bands (cumulatively 96.3% of the 160 mutants). The remaining six mutants were analyzed in a third condition (with 5% glycerol, 10 degrees C), and all of them showed shifted bands (cumulatively 100%). Sequencing of the restriction fragments with mobility shifts in the 160 mutants revealed 108 kinds of mutations, 100 (92.6%) being detected in the first condition, seven (cumulatively 99.1%) in the second condition, and one (cumulatively 100%) in the third condition. This method greatly reduced the time to identify lacI mutations, and allowed the detection of multiple mutations in one lacI mutant. The results also show that in general PCR-SSCP analysis is very sensitive when test fragments are shorter than about 250 base pairs and electrophoresis is performed under at least two conditions.

Animals↗
PubMed1995

Detection of mutagenicity of diphenyl ether herbicides in Salmonella typhimurium YG1026 and YG1021.

Three kinds of diphenyl ether herbicides, 4-nitrophenyl 2,4,6-trichlorophenyl ether (CNP, chlornitrofen), 2,4-dichlorophenyl 3-methoxy-4-nitrophenyl ether (chlomethoxynil) and 2,4-dichlorophenyl 3-methoxycarbonyl-4-nitrophenyl ether (bifenox), were tested for mutagenicity in Salmonella typhimurium YG1026 and YG1021, which have high nitroreductase activity, and also in S. typhimurium TA100 and TA98. CNP and chlomethoxynil showed mutagenicity in S. typhimurium YG1026, without S9 mix, inducing 50 and 304 revertants per microgram. These mutagenicities were suppressed by the addition of S9 mix. CNP and chlomethoxynil were also mutagenic to YG1021 with and without S9 mix, and their mutagenicities were lower than those to YG1026. On the other hand, bifenox was mutagenic to YG1026 only with S9 mix, inducing 3.0 revertants per micrograms. These three herbicides showed no mutagenicity in S. typhimurium TA100 and TA98 either with or without S9 mix.

Dose-Response Relationship, Drug↗
PubMed1995

Role of poly(ADP-ribose) polymerase in cell-cycle checkpoint mechanisms following gamma-irradiation.

A nuclear poly(ADP-ribose) polymerase (PARP) is activated by gamma-irradiation and consequently synthesizes poly(ADP-ribose) by binding to DNA strand-breaks. This property suggests that PARP is a DNA strand-break-signal generator. Meanwhile, the cell-cycle arrest occurs in G1 and G2 phases following gamma-irradiation. We found that PARP inhibitors including 3-aminobenzamide (3-AB) suppressed G1 arrest and enhanced G2 arrest following gamma-irradiation. These observations suggested that PARP is critical for the induction of G1 arrest and is also involved in the regulation of G2 arrest. Furthermore, the effects of 3-AB on the G1-arrest signal-transduction pathway were also studied. We found that p53 stabilization following gamma-irradiation was not inhibited but the p53-responsive transient increases of WAF1/CIP1/p21 and MDM-2 mRNA were suppressed by 3-AB. Therefore, it is suggested that PARP participates in G1-arrest signal-transduction pathway through the modulation of WAF1/CIP1/p21 and MDM-2 mRNA expression.

Animals↗
PubMed1995

Evaluation of pulmonary artery histopathologic findings in congenital heart disease: an in vitro study using intravascular ultrasound imaging.

OBJECTIVES: This study aimed to 1) compare in vitro intravascular ultrasound images of human pulmonary arteries with corresponding histologic sections, and 2) correlate the relation between intravascular ultrasound findings and Heath-Edwards pathologic grade of pulmonary vascular changes. BACKGROUND: The pathologic assessment of the pulmonary vascular bed is essential for diagnosis and management of congenital heart disease with pulmonary hypertension. METHODS: We evaluated and compared intravascular ultrasound images with histologic findings at identical sites in 40 pulmonary artery segments from 17 autopsy studies: group 1 = 7 patients with pulmonary hypertension (Heath-Edwards grade I to V, 20 segments); group 2 = 10 patients without cardiopulmonary disease (20 segments). RESULTS: In group 2, the pulmonary artery wall echo consisted of a single layer. In group 1, 1) all segments of pulmonary arteries from patients with pulmonary hypertension showed a three-layered appearance; 2) in patients with mild pulmonary hypertension (Heath-Edwards grades I and II), intravascular ultrasound demonstrated increased thickness of the echoluscent zone due to medial hypertrophy with no intimal reaction; 3) patients with severe pulmonary hypertension (Health-Edwards grade III or higher) had intravascular ultrasound findings of increased medial thickness and a bright inner layer from intimal hyperplasia; 4) percent wall thickness derived from intravascular ultrasound showed a significant correlation with that determined by histologic examination (r = 0.89, p = 0.0001, n = 20). CONCLUSIONS: Changes observed with intravascular ultrasound imaging correlate well with histopathologic grade. Thus, intravascular ultrasound may have significant utility in the evaluation of pulmonary vascular morphology in patients with pulmonary hypertension.

Adolescent↗
PubMed1995

Gene transfer and expression in progeny after intravenous DNA injection into pregnant mice.

Several methods that enable foreign genes to be transferred directly into germ cells and adult animals have been developed, which have stimulated great interest in manipulating genes in vivo. However, there have been no methods available for introducing genes into fetuses. We report here that a single intravenous injection of expression plasmid: lipopolyamine complexes into pregnant mice resulted in successful gene transfer into the embryos. The transgenes thus introduced were expressed in the fetuses and newborn progeny. This simple and new method of gene transfer into embryos will facilitate rapid analysis of transgene effects in the fetuses and will be useful for studying gene-deficient animal models to gain transgene functions at desired stages of embryogenesis.

Animals↗
PubMed1995

Reinnervation of peripheral nerve segments implanted into the hemisected spinal cord estimated by transgenic mice.

We investigated how far Schwann cells, which are the peripheral nerve elements supporting axonal regrowth, penetrate into the hemisected recipient spinal cord. C57BL/6 mice, which carry carcinoembryonic antigen as transgene, were used for transplantation study. These CEA transgenic mice were syngenic to C57BL/6 mice except for the expression of human CEA DNA. In the syngenic transplantation study, C57BL/6 mice were transplanted with the sciatic nerve of CEA-transgenic mice to the hemisected spinal cord. Schwann cell migration into the recipient spinal cord was detected by the PCR method. Transplanted Schwann cells migrated into the recipient spinal cord both rostrally and caudally at a distance of 2 mm from the graft-host interface until 21 days after transplantation. At 28 days after transplantation, the Schwann cells migrated rostrally at a distance of 2 mm and caudally at a distance of 4 mm. C57BL/6-CEA sciatic nerve was transplanted to BALB/C mice as the allogenic transplant. CEA DNA was detected until 14 days after transplantation, but disappeared at 21 days. In addition, C57BL/6-CEA sciatic nerves were transplanted into Wistar rats to study xenogenic transplantation. The CEA band disappeared at 10 days after transplantation. In conclusion, by using CEA transgenic mice and the PCR method, we could evaluate the mobility of Schwann cells which are thought to play an important role in axonal regeneration.

Animals↗
PubMed1995

Hst-1 (FGF-4) antisense oligonucleotides block murine limb development.

The initiation of limb development depends on the site specific proliferation of the mesenchyme by the signals from the apical ectodermal ridge (AER) in embryonic mouse. We have previously reported that the local expression of Hst-1/Fgf-4 transcripts in AER of the mouse limb bud is developmentally regulated, expressed at 11 and 12 days post coitus (p.c.) embryo. In an effort to further understand the role of Hst-1/FGF-4 in mouse limb development, an antisense oligodeoxynucleotides (ODNs) study was performed. We first established a novel organ culture system to study mouse limb development in vitro. This system allows mouse limb bud at 9.5-10-d p.c. embryo, when placed on a sheet of extracellular matrix in a defined medium, to differentiate into a limb at 12.5-d p.c. embryo within 4.5 d. Using this organ culture system, we have shown that exposure of 9.5-10-d p.c. embryonal limb bud explants to antisense ODNs of Hst-1/FGF-4 blocks limb development. In contrast, sense and scrambled ODNs have no inhibitory effect on limb outgrowth, suggesting that Hst-1/FGF-4 may work as a potent inducing factor for mouse limb development.

Animals↗
PubMed1995

Effects of docosahexaenoic acid (DHA) on intestinal polyp development in Apc delta 716 knockout mice.

Epidemiological studies and animal experiments show an association of dietary intake of fish oils and low incidence of several types of cancers. The active ingredients of fish oils appear to be polyunsaturated fatty acids of omega-3 type such as eicosapentaenoic acid and docosahexaenoic acid (DHA). We have investigated chemopreventive effects of DHA on mouse intestinal polyposis using adenomatous polyposis coli (Apc) gene knockout mice. Damage to the human APC gene is responsible for not only familial adenomatous polyposis but also many sporadic cancers of the entire digestive tract. Using homologous recombination in embryonic stem cells, we recently constructed gene knockout mice containing a truncation mutation in the Apc gene at codon 716 (Apc delta 716). The heterozygous mice developed numerous intestinal polyps, and all microadenomas dissected from the earliest polyps had already lost the wild-type allele, indicating the loss of heterozygosity [Oshima et al. (1995), Proc. Natl Acad. Sci. USA, 92, 4482-4486]. We fed Apc delta 716 heterozygotes with AIN-76A purified diet containing 3% DHA for 7 weeks, and scored the number and size of intestinal polyps. Average DHA intakes per day were 4.1 and 4.3 g/kg body wt for males and females, respectively. DHA-fed females had only 31% of polyps compared with the control females that developed about 220 polyps, whereas DHA-fed females showed no significant decrease in the polyp number. As for the polyp size, the proportion of larger polyps decreased more significantly in females than in males. This is the first demonstration that DHA inhibits intestinal polyposis induced by an Apc mutation at both its formation and growth.

Animals↗
PubMed1995

Marked increase in urinary excretion of nitrate and N-nitrosothioproline in the osteogenic disordered syndrome rats, lacking ascorbic acid biosynthesis, by administration of lipopolysaccharide and thioproline.

Urinary excretions of nitrate and N-nitrosothiazolidine-4-carboxylic acid (N-nitrosothioproline; NTPRO) were determined in rats with osteogenic disordered syndrome (ODS, od/od), lacking L-ascorbic acid (ASC) biosynthesis, after i.p. administration of Escherichia coli lipopolysaccharide (LPS, 1 mg/kg) followed by thiazolidine-4-carboxylic acid (thioproline, 20 mg/rat). L-Ascorbic acid-sufficient ODS rats showed the excretion of nitrate and NTPRO at the levels of 20.3 +/- 7.9 mumol/24h and 369 +/- 111 pmol/24 h respectively, whereas the levels of nitrate and NTPRO in ASC-deficient (scorbutic) rats increased to 54.7 +/- 5.6 mumol/24 h (P < 0.01) and 796 +/- 367 pmol/24 h (P < 0.05) respectively. Administration of L-arginine further increased urinary excretion of nitrate and NTPRO while D-arginine showed no effect. NG-Monomethyl-L-arginine, a specific inhibitor of nitric oxide synthase (NOS), strongly inhibited endogenous formation of both nitrate and NTPRO. These results indicate that increased excretion of NTPRO in ODS rats stimulated by LPS involves induction of NOS leading to an increase in endogenous formation of reactive nitrogen oxides such as N2O3, a potent nitrosating agent at physiological pH conditions. Increased NOS activities in the plasma and various tissues of ODS rats were observed 5 h after treatment with LPS. The possibility of extragastric N-nitroso compound formation in inflammation sites is discussed.

Animals↗
PubMed1995

Genetic polymorphisms and susceptibility to cancer development.

Humans show heterogeneous susceptibility to cancer development, suggesting the involvement of various genetic backgrounds in control of the production of endogenous carcinogens, the metabolism of carcinogens, the repair of DNA damage, cell proliferation and defence mechanisms including immune reactions. Gastric cancer is the major cancer in Japan. However, little is known about the genes linked with its development. In 1967, we found that N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) induced gastric cancers in Wistar rats. Subsequently the Buffalo strain of rats was reported to be resistant to MNNG stomach carcinogenesis, while ACI rats were very sensitive. In a carcinogenesis study using F1 and F2 rats, we suggested that this trait of MNNG stomach carcinogenesis-resistance was regulated by a single autosomal dominant allele. The O6-methylguanine adduct levels in gastric mucosa induced by MNNG were the same in Buffalo and ACI rats, but cell proliferation induced by MNNG was much higher in ACI than Buffalo animals. Chromosome mapping of the gene responsible for susceptibility to MNNG-induced carcinogenesis is now in progress and its identification will hopefully give us clues to the involvement of genetic traits in susceptibility to gastric cancer in humans. In addition, the genetic background of susceptibility to breast cancer is also being studied. In Japan, about 5% of all cases of breast cancer are familial. We have studied BRCA1, the breast cancer susceptibility gene, as a determinant of susceptibility to breast cancer by linkage analyses in 11 families, but our results indicate that BRCA1 may not be important for development of familial breast cancer in Japanese.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Formation and removal of DNA adducts in the liver of rats chronically fed the food-borne carcinogen, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline.

Effects of chronic administration of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) at 0.4, 8 and 400 ppm in the diet on DNA adduct formation and removal in the rat liver were examined by the 32P-postlabeling method. The 0.4 and 8 ppm doses for 40 weeks resulted in time-dependent increases in MeIQx-DNA adduct levels until 16 and 8 weeks, respectively, with constant values being maintained thereafter. In the case of a carcinogenic dose (400 ppm) of MeIQx, the adduct levels reached a maximum at week 12, and then gradually decreased. Alteration of metabolism of MeIQx during liver carcinogensis might be related to this decrease in DNA adduct levels. When MeIQx administration was stopped at week 20, 60-90% of the MeIQx-DNA adducts formed with the three doses (0.4, 8 and 400 ppm) of MeIQx were removed in a biphasic manner after return to a basal diet, with initial rapid removal followed by a slow change. No difference in the pattern of MeIQx-DNA adducts was detected on thin layer chromatography at any dose at any time point. Thus, it is suggested that there may be at least two types of damaged DNA, susceptible and resistant to removal of MeIQx-DNA adducts, after chronic administration of MeIQx.

Adenoma↗
PubMed1995

Serum antibody against unfused recombinant E7 protein of human papillomavirus type 16 in cervical cancer patients.

Sera were examined for the presence of antibody against E7 protein of human papillomavirus type 16 (HPV-16) by Western blot analysis using the bacterially derived unfused protein. The occurrence rates of anti-E7 antibody against HPV-16 were 14.1% (10/71) in cervical cancer patients, 0% (0/48) in cervical intraepithelial neoplasia patients, and 0% (0/41) in female non-malignant patients. Three patients (one with endometrial cancer, one with breast cancer, and one male patient with colon polyp) out of 115 patients with tumors in organs other than the cervix, had antibody against E7 protein of HPV-16. The serum antibody, once positive, could be detected for a long time after surgical removal of the cancers in all cases that could be followed up. HPV-16 DNA could be detected in 50% (13/26) of cervical cancer patients. Sixty-nine percent (9/13) of patients with HPV-16 DNA in cancers had the antibody and all the patients with stages II, III, and IV cervical cancer (8/8) harboring HPV-16 DNA showed the presence of the antibody against E7 protein of HPV-16. In contrast, only 20% (1/5) of cervical cancer patients with stage Ia or Ib harboring HPV-16 DNA showed positive for the anti-E7 antibody in sera. These findings suggest that the presence of anti-E7 antibody in serum depends on the staging of cervical cancer and extent of HPV infection.

Adult↗