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Biomedical subjects

R Inoue

Publications and source records attributed to R Inoue.

At least 91 records · Page 5Linked to original sources
PubMed1998

Chromosome aberrations induced in mice by chronic feeding of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ).

Dietary intake of mutagenic compounds is considered to be an important factor for the induction of some human cancers. Highly mutagenic compounds are known to be formed in meat during the cooking process. Since the discovery of such compounds, many studies have been conducted to evaluate their carcinogenic potential. One of the most mutagenic compounds formed in the cooking of meat is 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ). The recent development of mouse chromosome painting probes expand the capability of evaluating these food mutagens as potential clastogens in vivo. In this paper, we demonstrate the induction of chromosome aberrations in mice chronically exposed to MeIQ in their diet. CDF1 female mice were fed 400 ppm MeIQ beginning at 7 wk of age. At 76 wk of age, five control and eight exposed mice were euthanized. Blood and bone marrow cells were obtained and arrested in metaphase. Whole chromosome painting probes were used for fluorescence in situ hybridization of metaphase cells from blood and bone marrow. MeIQ-exposed mice were found to have a twofold increase in translocations and a 16-fold increase in fragments in their peripheral blood compared with controls. No aberrations were observed in the bone marrow. All organs were examined for the presence of tumours and routine histopathological analysis was performed on all organs as well as any tissue with macroscopic abnormalities. Forestomach and/or liver tumours developed in all but one of the mice fed MeIQ, but no such tumours were observed in the control mice. These data indicate that MeIQ is clastogenic and carcinogenic in vivo.

Animal Feed↗
PubMed1998

Esophageal varices in rat models of liver cirrhosis.

Animal models resembling the human situation are very useful to investigate human disease. However, there has been no evidence of esophageal varices in rats with liver cirrhosis. In the present study, to determine whether intrahepatic portal hypertension produced by liver cirrhosis induces esophageal varices in rats, the esophagus was examined endoscopically in rat models of liver cirrhosis. All rats given carbon tetrachloride or thioacetamide and six of seven rats given a choline-deficient diet had esophageal varices or venous dilatation after 16 weeks of treatment, although the varices in one rat given carbon tetrachloride and in two rats given a choline-deficient diet were reduced from weeks 16 to 18. These findings suggest that timing is important when studying esophageal varices in rat models of liver cirrhosis. It is concluded that certain models of liver cirrhosis in rats could be used as models of esophageal varices due to intrahepatic portal hypertension.

Animals↗
PubMed1998

Serum IgE level is negatively correlated with the ability of peripheral mononuclear cells to produce interferon gamma (IFNgamma): evidence of reduced expression of IFNgamma mRNA in atopic patients.

BACKGROUND: In patients with atopic diseases such as bronchial asthma and atopic dermatitis, an elevated serum IgE level is common. Several studies showed that interleukin-4(IL-4) and interferon-gamma (IFNgamma) are important for regulation of IgE production. OBJECTIVES: The study was designed to examine the pathogenesis of an elevated serum IgE level at the production levels of TH1-type and TH2-type cytokines. METHODS: The production of interleukin-2 (IL-2), IL-4, interleukin-5 (IL-5) and IFNgamma by peripheral blood mononuclear cells (PBMCs) stimulated with phytohemagglutinin (PHA) was analysed in 20 individuals with various serum IgE levels. The amount of IFNgamma mRNA in the stimulated PBMCs was analysed using a quantitative polymerase chain reaction method. RESULTS: Cytokine production was analysed simply as a function of serum IgE level. The serum IgE level was negatively correlated with the amount of IFNgamma secreted by PBMCs (n = 20, R = -0.724, P<0.005) when logarithmically transformed data were analysed, but were not or were only weakly correlated with those of IL-4, IL-2, or IL-5 secreted by these cells (n = 20). For investigation of the cause of reduced IFNgamma production in individuals whose serum IgE level are high, the amount of IFNgamma mRNA was determined. The levels of IFNgamma mRNA expression in the stimulated PBMCs correlated well with the amount of IFNgamma secreted by the PBMCs (n = 8, R = 0.947, P < 0.001). CONCLUSIONS: Reduced IFNgamma production ability due to reduced IFNgamma mRNA expression in PBMCs is associated with an elevated serum IgE level in atopic patients.

Adolescent↗
PubMed1998

Expression of Pax5 gene in human haematopoietic cells and tissues: comparison with immunodeficient donors.

In mice, Pax5 gene is indispensable for B cell development. Pax5-deficient mice fail to produce mature B cells owing to complete arrest of B cell development at a precursor stage. However, the lineage and stage of human Pax5 gene expression have remained elusive. In this investigation expression of the human Pax5 gene was studied. Pax5 gene expression was detected in B cell lines but not in myeloma cell lines. CD19 expression was correlated with Pax5 gene expression. Adult spleen and bone marrow and fetal spleen and liver showed strong Pax5 gene expression, as did the corresponding mouse tissues, as reported previously. In common variable immunodeficiency (CVID) peripheral blood lymphocytes (PBL) with a decreased number of B cells, no Pax5 gene expression was detected. Some CVID PBL stimulated with IL-2, IL-10 and anti-CD40 monoclonal antibody, expressed the Pax5 gene. Defect of Pax5 gene expression in CVID may be caused by regulatory T cell disorder.

Adolescent↗
PubMed1998

Sweet and sweetness-inducing activities of new triterpene glycosides, strogins.

In a previous study we isolated homologues of new oleanane-type triterpene glycosides from leaves of Staurogyne merguensis Kuntze and named them strogins. Strogins themselves have a sweet taste (sweet activity), which diminishes in a few minutes. Subsequent application of cold water to the mouth then elicits a sweet taste (sweetness-inducing activity). In the present study we systematically examined the properties of the sweet and sweetness-inducing activities of strogins. Strogins 1, 2 and 4 had both the sweet and sweetness-inducing activities, while strogins 3 and 5 had no activities. The sweetness-inducing activity in response to cold water lasted for 1 h for strogin 2 and 2 h for strogins 1 and 4. The sweetness-inducing activity was immediately diminished by application of gamma-cyclodextrin to the mouth after strogins were held in the mouth. It seems that the strogins were adsorbed on the gustatory receptor membranes and eliminated by inclusion activity of gamma-cyclodextrin. The structure of strogin resembles that of gymnemic acid, which has antisweet activity. There was competition between strogin 1 and gymnemic acid; treatment of the tongue with strogin 1 before application of Gymnema extract to the mouth reduced the antisweet activity. While the sweetness-inducing activity of curculin in response to water was suppressed by the presence of divalent cations such as Ca2+ or Mg2+, that of strogin was not suppressed by the divalent cations. The changes in the inactive complex between strogin and the sweet receptor site in the adaptation state into the active complex induced by cold stimulation were discussed.

Cations, Divalent↗
PubMed1998

Postsynaptic enhancement by motilin of muscarinic receptor cation currents in duodenal smooth muscle.

We have investigated a potential role of motilin in amplifying the postsynaptic muscarinic responses in the rabbit duodenal smooth muscle cells, using the whole cell variant of patch-clamp technique. Stimulation of motilin receptors by exogenously applied motilin (1 nM) resulted in a large increase in carbachol (CCh)-induced atropine-sensitive cation current (ICCh) at threshold concentrations of CCh (0.3-1 microM) at 30 degrees C. This potentiation was abolished in the presence of a specific blocker of motilin receptor (GM109) and was attenuated with increased concentrations of either motilin or CCh, being virtually absent with maximally effective concentrations of these agonists. Motilin failed to potentiate ICCh when the ambient temperature was reduced to 20 degrees C or if the cation current had been directly activated by internal perfusion with guanosine 5'-O-(3-thiotriphosphate) (50 microM) bypassing the muscarinic receptor. These results suggest that some biochemical processes, such as enzymatic reactions, might be involved in the motilin-induced potentiation and that its site of action might be the muscarinic receptor and/or associated G proteins.

Animals↗
PubMed1998

Physiological features of visceral smooth muscle cells, with special reference to receptors and ion channels.

Visceral smooth muscle cells (VSMC) play an essential role, through changes in their contraction-relaxation cycle, in the maintenance of homeostasis in biological systems. The features of these cells differ markedly by tissue and by species; moreover, there are often regional differences within a given tissue. The biophysical features used to investigate ion channels in VSMC have progressed from the original extracellular recording methods (large electrode, single or double sucrose gap methods), to the intracellular (microelectrode) recording method, and then to methods for recording from membrane fractions (patch-clamp, including cell-attached patch-clamp, methods). Remarkable advances are now being made thanks to the application of these more modern biophysical procedures and to the development of techniques in molecular biology. Even so, we still have much to learn about the physiological features of these channels and about their contribution to the activity of both cell and tissue. In this review, we take a detailed look at ion channels in VSMC and at receptor-operated ion channels in particular; we look at their interaction with the contraction-relaxation cycle in individual VSMC and especially at the way in which their activity is related to Ca2+ movements and Ca2+ homeostasis in the cell. In sections II and III, we discuss research findings mainly derived from the use of the microelectrode, although we also introduce work done using the patch-clamp procedure. These sections cover work on the electrical activity of VSMC membranes (sect. II) and on neuromuscular transmission (sect. III). In sections IV and V, we discuss work done, using the patch-clamp procedure, on individual ion channels (Na+, Ca2+, K+, and Cl-; sect. IV) and on various types of receptor-operated ion channels (with or without coupled GTP-binding proteins and voltage dependent and independent; sect. V). In sect. VI, we look at work done on the role of Ca2+ in VSMC using the patch-clamp procedure, biochemical procedures, measurements of Ca2+ transients, and Ca2+ sensitivity of contractile proteins of VSMC. We discuss the way in which Ca2+ mobilization occurs after membrane activation (Ca2+ influx and efflux through the surface membrane, Ca2+ release from and uptake into the sarcoplasmic reticulum, and dynamic changes in Ca2+ within the cytosol). In this article, we make only limited reference to vascular smooth muscle research, since we reviewed the features of ion channels in vascular tissues only recently.

Animals↗
PubMed1998

Identification of proteins whose amounts are altered by mutation in the pgsA gene of Escherichia coli.

We identified proteins whose amounts were altered in an Escherichia coli pgsA3 mutant lacking the potential to synthesize phosphatidylglycerolphosphate, a precursor of phosphatidylglycerol. Proteins whose amounts were increased in the mutant were protease Do, periplasmic oligopeptide-binding protein, tryptophanase, and an unidentified protein, while the decreased one was flagellin. Transformation of the mutant with a plasmid containing the wild type pgsA gene complemented the phenotype, indicating that the pgsA3 mutation is responsible for the phenotype.

Amino Acid Sequence↗
PubMed1998

Potentiating actions of lanthanum on ACh-induced cation current in guinea-pig ileal smooth muscle cells.

Potentiating actions of external lanthanum (La3+) on muscarinic receptor-activated nonselective cation current (Icat) were investigated in myocytes dissociated from the longitudinal muscle layer of guinea-pig ileum, with a whole-cell variant of the patch clamp technique. Icat was dissected from other membrane currents by loading Cs-aspartate into the cell. Application of submilimolar concentrations of La3+ following 300 microM ACh into the bath caused a dose-dependent increase in the amplitude of Icat. The apparent Kd value for this increase was 190 microM, with a cooperativity factor of 1.7. La(3+)-induced increase in Icat amplitude was not associated with either changes in the reversal potential of Icat or altered sensitivity of muscarinic receptor to ACh, and paralleled by the conductance increase of Icat, the maximum of which (Gmax) occurred at about 1 mM La3+. Voltage-jump experiments revealed that the rate of current relaxation at hyperpolarizing potentials was greatly reduced in the presence of La3+, and correspondingly the steady state activation curve shifted toward more negative potentials. Divalent cations such as Cd2+ or Ni2+, which have been known to block Icat, antagonized the augmentative effect of La3+ on Icat in a competitive fashion, suggesting that the site of their actions might be similar. Furthermore, single Icat activities induced by internal perfusion of GTP gamma S (100 microM) was also greatly enhanced by external addition of 1 mM La3+. Under current clamp conditions, 1 mM La3+ blocked spontaneous Ca2+ spike activities, but was almost without effect on the membrane depolarization induced by ACh. In contrast, milimolar concentrations of Cd2+ and Ni2+ abolished both Ca2+ spike activities and ACh-induced depolarization. Potential importance of La3+ as a tool to investigate the external Ca(2+)-dependence of Icat has been discussed.

Acetylcholine↗
PubMed1997

BRCA1 and BRCA2 Germline Mutations in Japanese with Hereditary Breast Cancer Families.

We examined germline mutations in BRCA1 and BRCA2 in 23 Japanese breast cancer families, using PCR-SSCP analysis. The same nonsense mutation (exon 5, Leu63ter) of BRCA1 was detected in two defferent families. Three different mutations resulting in a truncated BRCA2 protein (exon 9, 20, 24) were detected in three different families, including one male case of breast cancer. One base substitution mutation in BRCA2, A10462G, was detected in the other two families. Although the mean age of onset for breast cancer in families with the BRCA1-mutation was 50 years, the age of onset in families with the BRCA2-mutation was from 28 to 43 years. Among the 23 families examined, two families had members with ovarian cancers, three had members with prostate cancers, and one had a pancreatic cancer. However, none of these families was positive for the BRCA1 orBRCA2 mutation. Histopathologically, we observed a prevalence of histological grade 3 in BRCA1/2-associated familial breast cancers, because of nuclear atypia, structural atypia and mitotic activity. It is suggested that BRCA2 may play a more important role than BRCA1 in Japanese familial breast cancers, and these mutations are related to the aggressive nature and highly proliferative activity of the tumors.

Journal Article↗
PubMed1997

Heat shock-induced excessive relaxation of DNA in Escherichia coli mutants lacking the histone-like protein HU.

Plasmid DNA in exponentially growing Escherichia coli immediately relaxes after heat shock but the relaxed DNA re-supercoils rapidly, the despite continued presence of the heat shock conditions. We have now obtained genetic evidence indicating that the histone-like protein HU of E. coli is required for this re-supercoiling of DNA. Plasmid DNA in a hupA-hupB double gene-disruption mutant relaxed excessively after heat shock, while the relaxation of DNA in a himA-himD double gene-disruption mutant and in an hns insertion mutant was transient, thereby indicating that HU protein, but not IHF or H-NS proteins, is required for the re-supercoiling of DNA. Exposure of the hupA-hupB double mutant to a temperature of 50 degrees C led to both excessive relaxation of DNA and to a decrease in viable cell number but temperatures lower than 46 degrees C did not lead to these events. Based on these results, we propose that HU protein maintains the negative supercoiling of DNA during thermal stress and contributes to cellular thermotolerance in E. coli.

Bacterial Proteins↗
PubMed1997

Genetic changes induced by heterocyclic amines.

Clarification of the mutational fingerprints of HCAs offers a promising approach in the investigation of the role of heterocyclic amines (HCAs) in human carcinogenesis. We analyzed mutations in the tumor related genes of tumors induced by HCAs, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), which mainly yield DNA-adducts of C8-guanine. The G-->T transversion at codon 13-2nd position in Ha-ras was predominantly observed in mouse forestomach and rat Zymbal gland tumors induced by MeIQ. In contrast, various types of mutation were detected in the ras family genes of rat Zymbal gland tumors induced by IQ; the presence of a methyl group at position 4 of imidazo[4,5-f]quinoline gave rise to a remarkable difference in the mutational fingerprint. Apc mutations were detected in PhIP- and IQ-induced rat colon tumors, with incidences of 50% (4/8) and 15% (2/13), respectively. All five mutations detected in the four PhIP-induced tumors consisted of a guanine deletion from the 5'-GGGA-3' sequence, in contrast with T to C and C to T mutations in IQ-induced tumors. Four of these five mutations shared seven common nucleotides, -GTGGGAT- surrounding the guanine; indicating that PhIP leaves a characteristic mutational fingerprint in Apc. Colon tumors induced by PhIP were also found to have mutations in their microsatellite sequences, and similar results were detected in mammary gland tumors induced by PhIP, contrasting with no mutations in IQ-induced colon tumors and a very low frequency of mutations in 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors. Although the mechanisms involved in the induction of microsatellite mutations are not known yet, microsatellite mutations which can also be detected in sporadic human tumors, including colon and breast tumors, were indicated to be a characteristic of PhIP. Mammary tumors induced by PhIP showed loss of heterozygocity (LOH) at the distal part of chromosome 10, which shows synteny with the distal part of human chromosome 17, where LOH frequently occurs in human breast cancer. In conclusion, each heterocyclic amine leave a mutational fingerprint which is specific to each compound. Since the tumor-related genes involved in PhIP-induced tumors have characteristics in common with those in human cancers, further detailed analysis will provide us with useful information on mutational fingerprints, and on the possible contribution of PhIP to human colon cancer.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

BRCA2 germline mutations in Japanese breast cancer families.

Germline mutations of BRCA2 were examined in 20 Japanese breast cancer families without BRCA1 mutations, including one demonstrating cancer development in a male. Three different mutations, resulting in truncation of the BRCA2 protein, were detected in 3 different families. They were 9474insA (exon 24, termination at codon 3110), C8729A (exon 20, S2834 ter) and 982del4 (exon 9, termination at codon 275). The 982del4 mutation was detected in the family with a case of male breast cancer. Age at onset was young, with a range of 28-43 years, in the 2 female breast cancer families with truncation mutations. One probable missense mutation, A10462G (13412V), was further detected in 2 families, although cosegregation of this allele with the breast cancer phenotype was not complete. The rate of BRCA2 mutations in Japanese families was suggested to be almost the same as in Western countries, and larger than it is the case for BRCA1.

Adult↗
PubMed1997

Polyclonal B-cell lymphocytosis with features resembling hairy cell leukemia-Japanese variant.

Polyclonal B lymphocytosis was found in four patients having clinical and hematologic features resembling those of hairy cell leukemia (HCL). All four patients were women between 37 and 67 years of age. Three patients had splenomegaly. Lymphadenopthy was absent or slight. Persistent lymphocytosis was seen in all the patients, and anemia and/or thrombopenia was observed in three of the patients. Abnormal lymphocytes have long microvilli and prominent membranous ruffles on their surfaces. Bone marrow aspirates and biopsy specimens showed increased numbers of abnormal lymphocytes with round nuclei and abundant pale cytoplasm. Although these findings were similar to those of HCL, studies of Ig gene rearrangements and expression showed the polyclonal proliferation of B cells. We called this new disease hairy B-cell lymphoproliferative disorder (HBLD). All four patients exhibited a polyclonal increase in serum IgG. The morphology of the cells in HBLD was more similar to that of leukemia cells of a variant form of HCL (HCL-Japanese variant) than to typical HCL cells. The surface IgG+, CD5-, CD11c+, CD22+, CD24-, CD25- phenotype and the weak tartrate-resistant acid phosphatase activity in the cells were identical to those of HCL cells of the Japanese variant. Our findings suggest that the B cells in HBLD are the nonmalignant counterpart of leukemic B cells in HCL-Japanese variant.

Adult↗
PubMed1997

A convenient method for genotyping of human O6-methylguanine-DNA methyltransferase polymorphism.

O6-methylguanine-DNA methyltransferase (MGMT) is one of the DNA repair enzymes in mammals. We previously screened the variant alleles for the MGMT gene in the general population, and found three variants (V1, V2, V3), two of which caused amino acid substitutions (Leu84Phe for V1, and Trp65Cys for V2). In order to accelerate the ecogenetic and pharmacogenetic studies on MGMT polymorphism, we therefore developed a new PCR-based RFLP method for genotyping. The present method has some advantages over the initial PCR-single strand conformation polymorphism (SSCP) method, particularly regarding its simplicity, rapidity and specificity.

Alleles↗
PubMed1997

Hydrogen peroxide induced responses of cat tracheal smooth muscle cells.

1. The effects of hydrogen peroxide (H2O2) (10(-6)-10(-3) M) on membrane potential, membrane currents, intracellular calcium concentration, resting muscle tone and contractions elicited by electrical field stimulation (EFS) and carbachol were examined in cat tracheal strips and isolated smooth muscle cells. 2. H2O2 (10(-4) and 10(-5) M) enhanced the amplitude of contractions and excitatory junction potentials (e.j.p.) evoked by EFS without changing muscle tone and resting membrane potential of the tracheal smooth muscle, and enhanced the contraction induced by carbachol (10(-3) M). At an increased concentration (10(-3) M), H2O2 elevated resting muscle tone and marginally hyperpolarized the membrane in the majority of the cells. 3. In 51 out of 56 cells examined, H2O2 (10(-6)-10(-3) M) elicited an outward current at a holding potential of -40 mV and enhanced the frequency of the spontaneous transient outward current (STOC). In 20 cells the outward current was preceded by a small inward current. In the other cells, H2O2 elicited only an inward current or did not affect the background current. 4. In Ca2+ free solution the action of H2O2 on the resting muscle tone, STOCs, background current and on the current induced by ramp depolarization was significantly reduced. 5. H2O2 (10(-4) M) increased the intracellular ionized calcium concentration both in the absence and presence of external Ca2+. However, the effect developed faster and was of a higher amplitude in the presence of external Ca2+. 6. These results suggest that H2O2 increases intracellular Ca2+, with a subsequent augmentation of stimulation-evoked contractions, and enhances Ca2+ and voltage-sensitive potassium conductance.

Animals↗