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Biomedical subjects

K Tadokoro

Publications and source records attributed to K Tadokoro.

At least 19 recordsLinked to original sources
PubMed2005

Effect of CYP2C19 polymorphism on the safety and efficacy of omeprazole in Japanese patients with recurrent reflux oesophagitis.

BACKGROUND: The polymorphic enzyme cytochrome P450 2C19 affects omeprazole metabolism. This influence on metabolism might affect serum gastrin levels, and safety, during long-term treatment of reflux oesophagitis. AIM: To examine the relationship between cytochrome P450 2C19 genotype and the safety profile of long-term omeprazole treatment. METHODS: A total of 119 Japanese patients with recurrent reflux oesophagitis underwent cytochrome P450 2C19 genotyping prior to receiving daily omeprazole 10 mg or 20 mg for 6-12 months, during which adverse event frequency, serum gastrin levels and endoscopic findings were monitored. RESULTS: The incidences of adverse events, serious adverse events and adverse events leading to withdrawal did not differ between homozygous extensive metabolizer (n = 46), heterozygous extensive metabolizer (n = 53) or poor metabolizer (n = 20) groups. In all genotype groups, serum gastrin increased during the first 3 months of dosing but stabilized thereafter. No significant differences were seen either in the rate of reflux oesophagitis healing or symptom improvement among genotype groups. CONCLUSIONS: Long-term treatment with omeprazole was well-tolerated in Japanese patients, irrespective of their cytochrome P450 2C19 metabolic genotype, indicating that dose adjustment depending on metabolic genotype is not required during treatment with omeprazole.

Adult↗
PubMed2005

Epidemiology of blood donors in Japan, positive for hepatitis B virus and hepatitis C virus by nucleic acid amplification testing.

BACKGROUND AND OBJECTIVES: The Japanese Red Cross screens seronegative blood donors by nucleic acid amplification testing (NAT) for hepatitis B, hepatitis C and human immunodeficiency virus-1 markers. NAT-positive donors thus identified seemed to have a different infectious background from serologically positive donors. The purpose of our study was to characterize this background in the hepatitis B virus (HBV) and hepatitis C virus (HCV) NAT-positive donors. MATERIALS AND METHODS: Some 328 HBV DNA-positive and 44 HCV RNA-positive donors were detected by NAT testing of seronegative blood donors. These were characterized regarding age, gender and genotype of HBV and HCV. RESULTS: Those who were HBV NAT-positive were mainly young, in particular teenage girls. In Japan, genotypes C and B have previously been dominant, but recently genotype A has increased, and genotype H was recently detected. In HBV NAT-positive donors, the rate of genotype A was high (12.2%) compared with patients in hospital (1.7-2%). Donors who were HCV NAT-positive were also young, but mostly men in their twenties. The ratio of genotype 1b to 2a or 1b to 2b in HCV NAT-positive donors differed from that of hospitalized patients in Japan. We did not find genotype 1a, which is dominant in the USA. CONCLUSIONS: The high-risk donors detected by NAT were mainly young, with a different distribution of genotypes from that of hospitalized patients, regarding both HBV and HCV. The rare HBV genotype H has been found for the first time in Japan. The findings reflect the present spread of hepatitis viruses B and C.

Adolescent↗
PubMed2004

Analysis of enhancer activity of a dinucleotide repeat polymorphism in the neurotrophin-3 gene and its association with bipolar disorder.

Growing evidence has implicated the possible involvement of neurotrophins in the pathogenesis of functional psychoses such as schizophrenia and bipolar disorder. Previous studies reported a significant association of a dinucleotide repeat polymorphism of the neurotrophin-3 (NTF3) gene with schizophrenia. The aims of the present study were to examine whether this polymorphism is associated with bipolar disorder and whether the polymorphic region has an enhancer/silencer effect on transcriptional activity in an allele-dependent manner. In an association analysis between the polymorphism and bipolar disorder in a Japanese sample of 88 patients and 98 controls matched for age, sex, and ethnicity, the distribution of alleles did not differ significantly between the two groups. pGL3-promoter luciferase reporter vectors containing the polymorphic region increased luciferase activity relative to empty pGL3-promoter vector in HeLa, IMR-32 (neuroblastoma) and Hs683 (glioma) cell lines; however, no significant difference was detected between alleles for either cell line. Our results suggest that the examined polymorphism has no major role in giving susceptibility to bipolar disorder. Although the polymorphic region may have an enhancer-like effect on transcriptional activity, we obtained no evidence for allele-dependent differential effects.

Alleles↗
PubMed2001

Molecular cloning and characterization of six novel isoforms of human Bim, a member of the proapoptotic Bcl-2 family.

Bim protein is one of the BH3-only proteins, members of the Bcl-2 family that have only one of the Bcl-2 homology regions, BH3. BH3-only proteins are essential initiators of apoptotic cell death. Thus far, three isoforms of Bim have been reported, i.e. Bim(EL), Bim(L) and Bim(S). Here we report the cloning and characterization of six novel isoforms of human Bim, designated as Bimalpha1, alpha2, and beta1-beta4, which are generated by alternative splicing. Unlike the three known isoforms, none of these novel isoforms contained a C-terminal hydrophobic region. Among the novel isoforms, only Bimalpha1 and alpha2 contained a BH3 domain and were proapoptotic, although less potent than the classical isoforms. These two isoforms localized, at least in part, in mitochondria when transiently expressed in HeLa cells as a green fluorescent protein-fused form. These results suggest that the BH3 domain is necessary for induction of apoptosis and mitochondrial localization but not sufficient for the full proapoptotic activity. While the classical isoforms were always predominantly expressed in transformed cells, expression profiles of bim isoforms were highly variable among normal tissues at least in humans, suggesting a tissue-specific transcriptional regulation of bim.

Amino Acid Sequence↗
PubMed2001

In vitro anti-tumour activity of alpha-galactosylceramide-stimulated human invariant Valpha24+NKT cells against melanoma.

alpha-galactosylceramide (KRN 7000, alpha-GalCer) has shown potent in vivo anti-tumour activity in mice, including against melanoma and the highly specific effect of inducing proliferation and activation of human Valpha24+NKT-cells. We hypothesized that human Valpha24+NKT-cells activated by alpha-GalCer might exhibit anti-tumour activity against human melanoma. To investigate this, Valpha24+NKT-cells were generated from the peripheral blood of patients with melanoma after stimulation with alpha-GalCer pulsed monocyte-derived dendritic cells (Mo-DCs). Valpha24+NKT-cells did not exhibit cytolytic activity against the primary autologous or allogeneic melanoma cell lines tested. However, proliferation of the melanoma cell lines was markedly suppressed by co-culture with activated Valpha24+NKT-cells (mean +/- SD inhibition of proliferation 63.9 +/- 1.3%). Culture supernatants of activated Valpha24+NKT-cell cultures stimulated with alpha-GalCer pulsed Mo-DCs exhibited similar antiproliferative activities against melanoma cells, indicating that the majority of the inhibitory effects were due to soluble mediators rather than direct cell-to-cell interactions. This effect was predominantly due to release of IFN-gamma, and to a lesser extent IL-12. Other cytokines, including IL-4 and IL-10, were released but these cytokines had less antiproliferative effects. These in vitro results show that Valpha24+NKT-cells stimulated by alpha-GalCer-pulsed Mo-DCs have anti-tumour activities against human melanoma through antiproliferative effects exerted by soluble mediators rather than cytolytic effects as observed against some other tumours. Induction of local cytokine release by activated Valpha24+NKT-cells may contribute to clinical anti-tumour effects of alpha-GalCer.

Adjuvants, Immunologic↗
PubMed2001

Chemokine receptor expressions and responsiveness of cord blood T cells.

Chemokines and their receptors play a critical role in the selective attraction of various subsets of leukocytes. We examined the chemokine receptor expressions and responsiveness of cord blood (CB) T cells. Flow-cytometric analysis revealed that peripheral blood (PB) T cells expressed CCR-1, CCR-2, CCR-5, CCR-6, CXC chemokine receptor-3 (CXCR-3), and CXCR-4, while CB T cells expressed only CXCR-4 on their surface. Chemotactic migratory response of CB T cells to macrophage-inflammatory protein (MIP)-1alpha, monocyte chemoattractant protein-1, RANTES, MIP-3alpha, monokine induced by IFN-gamma, and IFN-gamma-inducible protein-10 was significantly impaired compared with those of PB T cells. In contrast, the ability of CB T cells to migrate to MIP-3beta, 6Ckine, and stromal cell-derived factor-1alpha was greater than that of PB T cells, and these events were correlated with the expression levels of CCR-7 and CXCR-4, respectively. Engagement of CD3 and CD28 specifically up-regulated CXCR-3 expression and chemotaxis to monokine induced by IFN-gamma and IFN-gamma-inducible protein-10, whereas this stimulation down-regulated CCR-7 expression and chemotaxis to MIP-3beta and 6Ckine in PB T cells, but not in CB T cells. These results suggest that PB T cells and CB T cells exhibit distinct chemokine responsiveness via different chemokine receptor repertoire.

Antibodies, Monoclonal↗
PubMed2001

Identification of novel single nucleotide substitutions in the NKp30 gene expressed in human natural killer cells.

Cytotoxicity of natural killer (NK) cells is regulated by a balance of signals from two kinds of NK receptors, activating receptors and inhibitory receptors. Natural cytotoxicity receptors (NCR) family, which consists of NKp30, NKp44 and NKp46, is a major human activating NK receptor. NKp30 has been mapped to the HLA class III region near tumor necrosis factor (TNF) family loci. We have analyzed the NKp30 gene of healthy Japanese and found two synonymous substitutions in the coding region, c.111G>A and c.156C>T, and also identified two single-nucleotide polymorphisms (SNPs) in the promotor region, -201G>A and -163G>C. Furthermore, it was confirmed that these polymorphisms of the NKp30 gene show strong linkage disequilibria with each other and with HLA-DRB1 or TNFA polymorphisms. Since susceptibilities to certain diseases were mapped near this region, the NKp30 polymorphisms could be useful genetic markers.

Alleles↗
PubMed2001

Activation of HIV-1-specific immune responses to an HIV-1 vaccine constructed from a replication-defective adenovirus vector using various combinations of immunization protocols.

We constructed a recombinant replication defective adenovirus vector containing the env gene (Ad-Bal) derived from macrophage-trophic HIV-1 (HIV-1 Bal). We then immunized mice with this vector using several administration routes and protocols, and examined the immune response. When the Ad-Bal viral vector (over 1 x 10(7) pfu) was injected subcutaneously, both humoral and cell-mediated immunities were induced. However, immune response induced by the Ad-Bal vector alone was weaker than that induced by the recombinant vaccinia viral vector. We then employed the following three immunization protocols: (l) DNA vaccination followed by immunization with the Ad-Bal; (2) vaccination using the Ad-Bal vector followed by DNA vaccination; and (3) DNA vaccination followed by Ad-Bal infection and passive transfer of dendritic cells (DCs) infected with the Ad-Bal. Among the three protocols, the last gave the strongest humoral and cell-mediated immunity. These results suggest that the combination of DNA vaccination, Ad-Bal vector infection and passive transfer of Ad-Bal-infected DCs can induce strong immunity against HIV-1 Bal.

AIDS Vaccines↗
PubMed2001

Dendritic cells rapidly undergo apoptosis in vitro following culture with activated CD4+ Valpha24 natural killer T cells expressing CD40L.

Human Valpha24 natural killer T (Valpha24NKT) cells are activated by alpha-glycosylceramide-pulsed dendritic cells (DCs) in a CD1d-dependent and T-cell receptor-mediated manner. There are two major subpopulations of Valpha24NKT cells, CD4- CD8- Valpha24NKT and CD4+ Valpha24NKT cells. We have recently shown that activated CD4- CD8- Valpha24NKT cells have cytotoxic activity against DCs, but knowledge of the molecules responsible for cytotoxicity of Valpha24NKT cells is currently limited. We aimed to investigate whether CD4+ Valpha24NKT cells also have cytotoxic activity against DCs and to determine the mechanisms underlying any observed cytotoxic activity. We demonstrated that activated CD4+ Valpha24NKT cells [CD40 ligand (CD40L) -positive] have cytotoxic activity against DCs (strongly CD40-positive), but not against monocytes (weakly CD40-positive) or phytohaemagglutinin blast T cells (CD40-negative), and that apoptosis of DCs significantly contributes to the observed cytotoxicity. The apoptosis of DCs following culture with activated CD4+ Valpha24NKT cells, but not with resting CD4+ Valpha24NKT cells (CD40L-negative), was partially inhibited by anti-CD40L mAb. Direct ligation of CD40 on the DCs by the anti-CD40 antibody also induced apoptosis of DCs. Our results suggest that CD40-CD40L interaction plays an important role in the induction of apoptosis of DCs following culture with activated CD4+ Valpha24NKT cells. The apoptosis of DCs from normal donors, triggered by the CD40-CD40L interaction, may contribute to the homeostatic regulation of the normal human immune system, preventing the interminable activation of activated CD4+ Valpha24NKT cells by virtue of apoptosis of DCs.

Antibodies, Monoclonal↗
PubMed2001

Analysis of HBV infection after blood transfusion in Japan through investigation of a comprehensive donor specimen repository.

BACKGROUND: To understand the risk of transfusion-transmitted viral infection, it is important to precisely assess cases of infection that follow transfusion. STUDY DESIGN AND METHODS: HBV infections noted after transfusion in 1997, 1998, and 1999 were analyzed. Transfusion in all these cases was performed before NAT was adopted for donor screening. To detect viral infection, PCR and serologic tests for HBV were performed retrospectively on all blood samples from implicated donors that had been stored in a frozen state after each donation. The concentration of HBV genome was measured in HBV-positive blood samples. RESULTS: One hundred three cases of HBV infection were analyzed; of these, only 16, including at least 10 infections due to window-period (HBsAg-positive by reverse particle hemagglutination assay) donations, were confirmed by further testing to be related to transfusion. The concentrations of HBV genome were very low in four blood samples (<50, 400, 500, and 800 genome equivalents/mL of plasma). CONCLUSIONS: The remaining risk of transfusion transmission of HBV infection before the adoption of NAT was mainly due to window-period donations, including one that was made before the HBV genome was detectable by PCR. However, it was determined that transfusion was not responsible in many cases for HBV infection after transfusion.

Blood Donors↗
PubMed2001

Rapid and wide-reaching delivery of HIV-1 env DNA vaccine by intranasal administration.

Although the potential of DNA vaccination is now beginning to be greatly appreciated, no detailed study of its localization in tissue or its expression kinetics has been reported. In this study, we investigated these issues using HIV-1 DNA plasmids administered either intranasally or intramuscularly. Fluorescence in situ hybridization (FISH) revealed that the human immunodeficiency virus (HIV) plasmids administered intranasally localized in the alveoli, lung, liver, spleen, regional lymph nodes, kidney, fetus, and esophagus. These HIV plasmids were detected 2 to 4 weeks after administration. We detected messenger RNA production of HIV env gene in the lung, liver and spleen, and human immunodeficiency virus type 1 (HIV-1)-specific proteins were detectable in the lung. These observations may provide important information for understanding the mechanisms of strong immune activation induced by DNA vaccination via the intranasal route. This technology of DNA administration suggests possible practical applications for vaccination and probably for gene therapy.

AIDS Vaccines↗
PubMed2001

Signaling events following chemokine receptor ligation in human dendritic cells at different developmental stages.

Responsiveness of dendritic cells (DC) to inflammatory CC chemokines is down-regulated during their maturation. We analyzed the mechanism underlying these events. Cell-surface expression of CC chemokine receptor (CCR)-1, -3 and -5 was increased during differentiation of immature DC (iDC) from monocytes. In contrast, these expressions were decreased during development of iDC into mature DC (mDC) to levels similar to those of monocytes. Transcriptional expression of CCR-1, -3 and -5 was increased during differentiation of iDC from monocytes, while the expression was decreased during development of iDC into mDC. Expression of CCR-7 transcript was detected in mDC, but not in monocytes or iDC. Both monocytes and iDC, but not mDC, migrated in response to inflammatory CC chemokines such as regulated on activation normal T cell expressed and secreted (RANTES)/CCL5, whereas mDC, but not monocytes or iDC, migrated to macrophage inflammatory protein (MIP)-3ss/CCL19. Receptor engagement of monocytes or iDC by RANTES (for CCR-1, -3 and -5) resulted in protein tyrosine phosphorylation events including activation of focal adhesion kinase as well as mitogen-activated protein kinase, whereas this stimulation induced little activation of these molecular events in mDC when compared with monocytes or iDC. On the other hand, stimulation with MIP-3ss (for CCR-7) induced tyrosine phosphorylation events in mDC, but not in monocytes or iDC. These results suggest that the down-regulation of cell-surface expression of CCR and of their downstream signaling events may be involved in the reduced chemotaxis of DC to inflammatory CC chemokines during their maturation.

Cell Differentiation↗
PubMed2000

Alpha-glycosylceramides enhance the antitumor cytotoxicity of hepatic lymphocytes obtained from cancer patients by activating CD3-CD56+ NK cells in vitro.

Alpha-glycosylceramides, such as alpha-galactosylceramide and alpha-glucosylceramide, induce antitumor immunity in various murine cancer models. In the murine hepatic metastasis model, V alpha 14 TCR+NK1.1+ T cells, which accumulate preferentially in the liver, are considered to play a key role in the induction of antitumor immunity by alpha-glycosylceramides. We recently reported that V alpha 24 TCR+ NKT cells, the human homologues of murine V alpha 14 TCR+NK1.1+ cells, are rarely seen among freshly isolated human hepatic lymphocytes. Therefore, it is important to examine whether alpha-glycosylceramides also enhance the antitumor cytotoxicity of human hepatic lymphocytes, as they have been shown to do in murine systems, to determine the usefulness of alpha-glycosylceramides in cancer immunotherapy in humans. Here, we show that alpha-glycosylceramides greatly enhance the cytotoxicity of human hepatic lymphocytes obtained from cancer patients against the tumor cell lines, K562 and Colo201, in vitro. The direct effector cells of the elicited cytotoxicity were CD3-CD56+ NK cells. Even though V alpha 24 TCR+NKT cells proliferated remarkably in response to alpha-glycosylceramides, they did not contribute directly to the cytotoxicity. Our observations strongly suggest the potential usefulness of alpha-glycosylceramides for immunotherapy of liver cancer in humans based on their ability to activate CD3-CD56+ NK cells in the liver.

Adjuvants, Immunologic↗
PubMed2000

IL-12 responsiveness and expression of IL-12 receptor in human peripheral blood monocyte-derived dendritic cells.

We analyzed the expression of IL-12Rbeta1 and IL-12Rbeta2 and the role of IL-12 in the activation of monocyte-derived dendritic cells (DCs) via IL-12Rbeta1-mediated signaling events. Flow cytometric analysis revealed that IL-12Rbeta1 was expressed in T cells, Con A blasts, and monocyte-derived DCs, but not in monocytes, while its transcript was detected in all of these cell types. Transcriptional expression of IL-12Rbeta2 was observed in T cells, Con A blasts, and monocyte-derived DCs, but not monocytes. The ligation of DCs as well as Con A blasts by IL-12 induced the production of GM-CSF, IL-1beta, IL-6, TNF-alpha, and IFN-gamma at the transcription levels. Furthermore, stimulation of DCs with IL-12 induced IL-12p40 transcript, but not IL-12p35 transcript, whereas this stimulation caused the expressions of both transcripts in Con A blasts. Stimulation of DCs with IL-12 caused a tyrosine phosphorylation of several intracellular proteins, and the pattern of these events were distinct from those of IL-12-stimulated Con A blasts. IL-12 also induced tyrosine phosphorylation of IL-12Rbeta1 as well as recruitment of several tyrosine-phosphorylated proteins to IL-12Rbeta1 in DCs and Con A blasts. Receptor engagement of DCs as well as Con A blasts by IL-12 resulted in activation of Janus kinase 2 and Tyk2 kinases and Stat3 and Stat4 transcription factors and the association of these proteins to IL-12Rbeta1. Stimulation with IL-12 caused a tyrosine phosphorylation and enzymatic activity of a family of mitogen-activated protein kinases, p38mapk. These results suggest that IL-12 acts directly on DCs to induce their functional activation via IL-12Rbeta1-mediated signaling events.

Cells, Cultured↗
PubMed2000

Protein binding of a DRPLA family through arginine-glutamic acid dipeptide repeats is enhanced by extended polyglutamine.

Dentatorubral-pallidoluysian atrophy (DRPLA) is one of the hereditary neurodegenerative disorders caused by expansion of CAG/glutamine repeats. To investigate the normal function of the DRPLA gene and the pathogenic mechanism of neuron death in specific areas of the brain, we isolated and analyzed a gene that shares a notable motif with DRPLA, arginine-glutamic acid (RE) dipeptide repeats. The gene isolated, designated RERE, has an open reading frame of 1566 amino acids, of which the C-terminal portion has 67% homology to DRPLA, whereas the N-terminal portion is distinctive. RERE also contains arginine-aspartic acid (RD) dipeptide repeats and putative nuclear localization signal sequences, but no polyglutamine tracts. RERE is expressed at a low level in most tissues examined. Immunoprecipitation and in vitro binding assays demonstrate that the DRPLA and RERE proteins bind each other, for which one of the RE repeats has a primary role, and extended polyglutamine enhances the binding. With engineered constructs fused with a tag, the RERE protein localized predominantly in the nucleus. Moreover, when RERE is overexpressed, the distribution of endogenous DRPLA protein alters from the diffused to the speckled pattern in the nucleus so as to co-localize with RERE. More RERE protein is recruited into nuclear aggregates of the DRPLA protein with extended polyglutamine than into those of pure polyglutamine. These results reveal a function for the DRPLA protein in the nucleus and the RE repeat in the protein-protein interaction.

Amino Acid Sequence↗
PubMed2000

Analysis of human V alpha 24+ CD4+ NKT cells activated by alpha-glycosylceramide-pulsed monocyte-derived dendritic cells.

Human V alpha 24+ NKT cells with an invariant TCR (V alpha 24-J alpha Q) have been shown to be specifically activated by synthetic glycolipids such as alpha-galactosylceramide and alpha-glucosylceramide in a CD1d-restricted and V alpha 24 TCR-mediated manner. We recently characterized V alpha 24+ CD4- CD8- double negative (DN) NKT cells using alpha-galactosylceramide-pulsed monocyte-derived dendritic cells. Here, we compare V alpha 24+ CD4+ NKT cells with human V alpha 24+ DN NKT cells from the same donor using alpha-galactosylceramide-pulsed monocyte-derived dendritic cells. Human V alpha 24+ CD4+ NKT cells were phenotypically and functionally similar to the human V alpha 24+ DN NKT cells characterized previously. Both of them use V alpha 24-J alpha Q-V beta 11 TCR and express CD161 (NKR-P1A), but not the other NK receptors tested so far. They also produce cytokines such as IL-4 and IFN-gamma, and, in regard to IL-4 production, V alpha 24+ CD4+ NKT cells produce more IL-4 than V alpha 24+ DN NKT cells. The cells exhibit marked cytotoxic activity against the U937 tumor cell line, but not against the NK target cell line, K562. Although at least some of the factors responsible for the stimulation of V alpha 24+ NKT cells have been clarified, little is known regarding the killing phase of these cells. Here we show that the cytotoxic activity of V alpha 24+ NKT cells against U937 cells is mediated mainly through the perforin pathway and that ICAM-1/LFA-1 as well as CD44/hyaluronic acid interactions are important for the effector phase of V alpha 24+ NKT cell-mediated cytotoxicity against U937 cells.

Antigens, CD1↗