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O Saitoh

Publications and source records attributed to O Saitoh.

At least 19 recordsLinked to original sources
PubMed2006

Possible association between nonsynonymous polymorphisms of the anaplastic lymphoma kinase (ALK) gene and schizophrenia in a Japanese population.

We examined, for the first time, the possible association between schizophrenia and the anaplastic lymphoma kinase (ALK) gene which plays an important role in neurodevelopment. When two nonsynonymous polymorphisms (Arg1491Lys and Glu1529Asp) were examined, there were significant differences in genotype and allele distributions between patients and controls. Individuals homozygous for the minor allele (1491Lys-1529Asp) were more common in patients than in controls (p = 0.0064, odds ratio 2.4, 95% CI 1.3-4.6). These results suggest that genetic variations of the ALK gene might confer susceptibility to schizophrenia.

Alleles↗
PubMed2005

Adenovirus-mediated gene delivery of interleukin-10, but not transforming growth factor beta, ameliorates the induction of Graves' hyperthyroidism in BALB/c mice.

Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) are well known anti-inflammatory cytokines. We have studied the effect of adenovirus-mediated IL-10 and TGF-beta gene delivery on the induction of Graves' hyperthyroidism in our mouse model that involves repeated injections of adenovirus expressing the thyrotropin receptor A subunit (AdTSHR). We first constructed adenoviruses encoding the two cytokines (AdIL10 and AdTGF(beta)) and confirmed expression by in vitro infection of COS cells. Susceptible BALB/c mice were injected twice with AdTSHR alone or together with AdIL10 or AdTGF(beta), and bled two weeks after the second immunization. Significantly elevated serum thyroxine levels were seen in 26% of mice immunized with AdTSHR and AdIL10 versus 61% with AdTSHR alone. Levels of thyroid stimulating antibody, but not nonstimulating antibody, were also decreased, and TSHR-specific splenocyte secretion of interferon-gamma in recall assays was impaired in mice treated with AdIL10. In contrast, AdTGF(beta) had little effect on hyperthyroidism. Overall, our findings demonstrate that gene delivery of IL-10, but not TGF-beta, suppresses the induction of Graves' hyperthyroidism in a mouse model. However, the effect of IL-10 is less powerful than we observed previously with T helper type 2-inducers including adenovirus expressing IL-4, Shistosoma mansoni infection or alpha-galactosylceramide.

Adenoviridae↗
PubMed2004

TSH receptor-adenovirus-induced Graves' hyperthyroidism is attenuated in both interferon-gamma and interleukin-4 knockout mice; implications for the Th1/Th2 paradigm.

The role of the Th1/Th2 balance in the pathogenesis of murine Graves' hyperthyroidism is controversial. In BALB/c mice injected with adenovirus expressing TSH receptor (TSHR-adeno model), we found that suppression of TSHR-specific Th1 immune responses by exogenous interleukin-4 (IL-4), alpha-galactosylceramide or helminth (Schistosoma mansoni) infection was associated with inhibition of hyperthyroidism, indicating the critical role for Th1 cytokines. In contrast, BALB/c IL-4 knockout (KO), but not interferon-gamma (IFN-gamma) KO mice failed to develop Graves' hyperthyroidism when injected with TSHR-expressing M12 B lymphoma cells (TSHR-M12 model), suggesting the importance of Th2 cytokine IL-4. To reconcile differences in these two models, we used IL-4 KO and IFN-gamma KO BALB/c mice in the TSHR-adeno model. Unlike wild-type (wt) BALB/c mice in which 60% developed hyperthyroidism, only 13 and 7% of IL-4 KO and IFN-gamma KO mice, respectively, became hyperthyroid. Thyroid stimulating antibodies were positive in most hyperthyroid mice. TSHR antibody titres determined by TSH binding inhibition and ELISA were comparable in all three groups. IgG1 and IgG2a TSHR antibody titres were similar in IFN-gamma KO and wt mice, whereas IgG1 TSHR antibody titres and TSHR-specific splenocyte IFN-gamma secretion were lower in IL-4 KO than in IFN-gamma KO and wt mice, respectively. Our results clearly implicate both IFN-gamma and IL-4 in development of hyperthyroidism in the TSHR-adeno model. These data, together with the previous report, also indicate different cytokine requirements in these two Graves' models, with IFN-gamma being more important in the TSHR-adeno than the TSHR-M12 model. Moreover, our previous and present observations indicate a difference in the role of exogenous versus endogenous IL-4 in TSHR-adenovirus induced Graves' hyperthyroidism.

Adenoviridae↗
PubMed2001

RGS8 protein is distributed in dendrites and cell body of cerebellar Purkinje cell.

RGS8 was originally identified as an RGS protein specifically expressed in neuronally differentiated P19 cells. We generated a polyclonal antibody specific to rat RGS8 using a synthetic peptide. When nonneural cells (DDT1MF2, CHO, and NIH3T3) transfected with rat RGS8 cDNA were immuno-stained with this antibody, the RGS8 protein was mainly detected in the nuclei. Since RGS8 mRNA was exclusively expressed in Purkinje cells of the cerebellum in the rat brain, we further examined the cellular distribution of the RGS8 protein in Purkinje cells using cultured cerebellar cells and tissue sections of the cerebellum. The RGS8 protein was excluded from the nuclei and distributed in the cell body and dendrites, but not in the axons of Purkinje cells. These results demonstrate the presence of a mechanism controlling the distribution of RGS8 protein in cerebellar Purkinje cells.

3T3 Cells↗
PubMed2001

Heteromeric association creates a P2Y-like adenosine receptor.

Adenosine and its endogenous precursor ATP are main components of the purinergic system that modulates cellular and tissue functions via specific adenosine and ATP receptors (P1 and P2 receptors), respectively. Although adenosine inhibits excitability and ATP functions as an excitatory transmitter in the central nervous system, little is known about the ability of P1 and P2 receptors to form new functional structures such as a heteromer to control the complex purinergic cascade. Here we have shown that G(i/o) protein-coupled A1 adenosine receptor (A1R) and Gq protein-coupled P2Y1 receptor (P2Y1R) coimmunoprecipitate in cotransfected HEK293T cells, suggesting the oligomeric association between distinct G protein-coupled P1 and P2 receptors. A1R and P2Y2 receptor, but not A1R and dopamine D2 receptor, also were found to coimmunoprecipitate in cotransfected cells. A1R agonist and antagonist binding to cell membranes were reduced by coexpression of A1R and P2Y1R, whereas a potent P2Y1R agonist adenosine 5'-O-(2-thiotriphosphate) (ADPbetaS) revealed a significant potency to A1R binding only in the cotransfected cell membranes. Moreover, the A1R/P2Y1R coexpressed cells showed an ADPbetaS-dependent reduction of forskolin-evoked cAMP accumulation that was sensitive to pertussis toxin and A1R antagonist, indicating that ADPbetaS binds A1R and inhibits adenylyl cyclase activity via G(i/o) proteins. Also, a high degree of A1R and P2Y1R colocalization was demonstrated in cotransfected cells by double immunofluorescence experiments with confocal laser microscopy. These results suggest that oligomeric association of A1R with P2Y1R generates A1R with P2Y1R-like agonistic pharmacology and provides a molecular mechanism for an increased diversity of purine signaling.

Adenosine↗
PubMed2001

Medium-chain fatty acids stimulate interleukin-8 production in Caco-2 cells with different mechanisms from long-chain fatty acids.

BACKGROUND AND AIM: It has been suggested that dietary fat exacerbates intestinal inflammation. We investigated the effect of fatty acids on interleukin (IL)-8 production in a human intestinal epithelial cell line (Caco-2). METHODS: The cells were cultured as monolayers on microporous membranes in culture inserts. Oleic acid (OA), capric acid (CA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were applied to the apical compartment of Caco-2 cell monolayers. The concentration of IL-8 in the basolateral medium was measured by using enzyme-linked immunosorbent assay, and the expression of IL-8 mRNA was measured by using competitive reverse transcription--polymerase chain reaction. Protein kinase C inhibitors (GF109203X and calphostin C) and H-7 (a protein kinase inhibitor) were used to study the mechanisms by which IL-8 production is stimulated. RESULTS: Both OA and CA enhanced IL-8 production (approximately fivefold), whereas DHA and EPA did not. Both OA and CA also enhanced IL-1-induced IL-8 production. The onset of OA-induced IL-8 production was delayed compared with that of CA-induced IL-8 production. Both OA and CA enhanced IL-8 mRNA expression (approximately fivefold) after 6 and 3 h, respectively. The protein kinase inhibitor (H-7) reduced both OA- and CA-induced IL-8 production by 88.0 and 85.9%, respectively. The protein kinase C inhibitors (GF109203X and calphostin C) reduced OA-induced IL-8 production by 29.3 and 54.5%, respectively, but showed no effect on CA-induced IL-8 production. CONCLUSIONS: These findings suggest that not only OA but also CA stimulates IL-8 production in intestinal epithelial cells, and the mechanisms of action differ between OA and CA.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2001

Development of the hippocampal formation from 2 to 42 years: MRI evidence of smaller area dentata in autism.

Autism, a neuropsychiatric disorder that severely impairs social, language and cognitive development, has a clinical onset in the first years of life. Because components of the limbic system mediate memory, social and affective functions that are typically disturbed in autism, a developmental defect in the limbic system has been hypothesized to underlie different autistic symptoms, but no developmental study has been performed. To obtain neuroanatomical evidence of limbic system abnormality in autism, we measured the cross-sectional area of the area dentata (AD; dentate gyrus + CA4) and combined area of the subiculum and CA1-CA3 (CAS) using in vivo MRI. Autistic patients aged 29 months to 42 years (n = 59) and healthy normal controls (n = 51) participated. The cross-sectional area of the AD was significantly smaller than normal in autism, the largest deviation from normal size (-13.5%) being found in autistic children aged 29 months to 4 years. Strong age-related increases were seen in the cross-sectional area of CAS, but autistic and normal subjects were not significantly different. This is the first direct evidence that anatomical abnormality within the limbic system exists from the earliest years of the disorder, and persists throughout development and to middle age.

Adolescent↗
PubMed2000

Regulator of G protein signaling 8 (RGS8) requires its NH2 terminus for subcellular localization and acute desensitization of G protein-gated K+ channels.

Functional roles of the NH(2)-terminal region of RGS (regulators of G protein signaling) 8 in G protein signaling were studied. The deletion of the NH(2)-terminal region of RGS8 (DeltaNRGS8) resulted in a partial loss of the inhibitory function in pheromone response of yeasts, although Galpha binding was not affected. To examine roles in subcellular distribution, we coexpressed two fusion proteins of RGS8-RFP and DeltaNRGS8-GFP in DDT1MF2 cells. RGS8-RFP was highly concentrated in nuclei of unstimulated cells. Coexpression of constitutively active Galpha(o) resulted in translocation of RGS8 protein to the plasma membrane. In contrast, DeltaNRGS8-GFP was distributed diffusely through the cytoplasm in the presence or absence of active Galpha(o). When coexpressed with G protein-gated inwardly rectifying K(+) channels, DeltaNRGS8 accelerated both turning on and off similar to RGS8. Acute desensitization of G protein-gated inwardly rectifying K(+) current observed in the presence of RGS8, however, was not induced by DeltaNRGS8. Thus, we, for the first time, showed that the NH(2) terminus of RGS8 contributes to the subcellular localization and to the desensitization of the G protein-coupled response.

Active Transport, Cell Nucleus↗
PubMed2000

Neural correlates of memory organization deficits in schizophrenia. A single photon emission computed tomography study with 99mTc-ethyl-cysteinate dimer during a verbal learning task.

Regional cerebral blood flow (rCBF) during a verbal learning task was measured using 99mTc-ethyl-cysteinate dimer and single photon emission computed tomography in 10 patients with schizophrenia and nine normal controls. Verbal repetition was used as a control task. The schizophrenic patients showed failure to spontaneously utilize implicit category information to learn the word lists. In the normal controls, rCBF in the left inferior frontal and left anterior cingulate regions was significantly increased during the verbal learning task, compared with the verbal repetition task. In contrast, there was no significant frontal lobe activation by the verbal learning in the schizophrenic patients. The patients had lower rCBF during the verbal learning task than the controls in the bilateral inferior frontal, left anterior cingulate, right superior frontal, and bilateral middle frontal regions. Activation in the left inferior frontal region was significantly positively correlated with categorical clustering in the task in the controls, but no such correlation was found in the patients. These results indicate that memory organization deficits in schizophrenia may be related to dysfunction in the prefrontal areas, especially in the left inferior frontal region.

Adult↗
PubMed2000

Molecular cloning and characterization of Xenopus RGS5.

We identified six genes that encode putative RGS proteins (XRGSI-VI) in developing Xenopus embryos using PCR amplification with degenerate primers corresponding to the conserved region (RGS domain) of known RGS proteins. RT-PCR analysis revealed that mRNAs of these XRGSs are differentially expressed during embryogenesis. At stage 1, only XRGSII mRNA was detected. On the other hand, expression of XRGSVI mRNA increased apparently at stage 14 and expression of three of other XRGS (III, IV, V) elevated between stage 25 and 40. To further characterize XRGS proteins expressed in Xenopus embryos, we isolated a cDNA clone for XRGSIII. Based on determined nucleotide sequence, XRGSIII was considered as a Xenopus homologue of mammalian RGS5 (XRGS5). Genetic analysis using the pheromone response halo assay showed that expression of XRGS5 inhibits yeast response to alpha-factor, suggesting that XRGS5 negatively regulates the G-protein-mediated signaling pathway in developing Xenopus embryos.

Amino Acid Sequence↗
PubMed2000

Plasma homovanillic acid in the prodromal phase of schizophrenia.

BACKGROUND: Plasma levels of homovanillic acid (pHVA) have been used as a peripheral measure of central dopaminergic activity. Despite a large body of studies investigating pHVA in schizophrenia, little is known about pHVA in patients in the prodromal phase of the illness. METHODS: Plasma HVA levels of 12 male outpatients meeting DSM-III-R criteria for the prodromal phase of schizophrenia at the time of blood sampling (who later developed psychotic symptoms) were compared with those of 12 normal male healthy volunteers. Task amounts in the Kraepelin arithmetic test at the time of blood sampling were compared between the prodromal patients and normal controls and were correlated with pHVA levels. RESULTS: The prodromal patients had significantly higher pHVA levels compared with normal control subjects. The mean amount of the arithmetic task for the prodromal patients was significantly less than that for controls. In the patient group, a significant negative correlation was observed between pHVA levels and the task amounts. CONCLUSIONS: Data from the present study indicate the presence of dopaminergic dysfunction in the prodromal stage of schizophrenia that is associated with neuropsychological impairment. Increased pHVA levels in the prodromal patients may have implications for early detection of schizophrenia.

Acute Disease↗
PubMed2000

Acquired ileal diverticulum: an unusual bleeding source.

Acquired ileal diverticulum is an uncommon condition and diagnosis is often difficult when bleeding occurs from this source. Here we describe two cases of ileal diverticulum with massive bleeding. Both patients presented with anal bleeding, but upper and lower gastrointestinal endoscopy did not reveal the source. Selective visceral angiography finally detected bleeding lesions in the terminal ileum. Surgical resection was performed in both patients, confirming that the bleeding arose from diverticula less than 1 cm in size. In patients with obscure gastrointestinal bleeding, an ileal diverticulum should be considered, and selective visceral angiography should be performed for precise diagnosis.

Aged↗
PubMed2000

Therapeutic effect of intracolonically administered nuclear factor kappa B (p65) antisense oligonucleotide on mouse dextran sulphate sodium (DSS)-induced colitis.

Cytokines such as IL-1, tumour necrosis factor-alpha (TNF-alpha), IL-6 and IL-8 are increased in inflamed colonic mucosa after administration of mouse DSS. Nuclear factor kappaB (NF-kappaB) is a transcription factor which regulates the expression of these cytokine genes. The effect of intracolonically administered NF-kappaB (p65) antisense phosphorothioate oligonucleotide was examined in mouse DSS-induced colitis using drinking water containing 5% DSS. When antisense oligonucleotide was given on day 0, the disease activity index (DAI) representing clinical symptoms improved and the histological score decreased; furthermore, IL-1, IL-6, and TNF-alpha concentrations in rectal mucosa were lower compared with the control group. Clinical and histological improvement was also observed when antisense oligonucleotide was begun on day 2 but not on day 7. In addition, the distribution of antisense oligonucleotides was investigated by confocal laser microscopy. In colonic mucosa, oligonucleotides were predominantly localized to cells in the lamina propria, but also in the epithelium. Western blot analysis using homogenized rectal mucosa showed the decreased expression of NF-kappaB p65 in the antisense oligonucleotide-treated group, although it was increased in the colitis group. These results suggest that intracolonic administration of NF-kappaB antisense oligonucleotide may be effective in ulcerative colitis.

Administration, Oral↗
PubMed2000

Accuracy of detection of colorectal neoplasia using an immunochemical occult blood test in symptomatic referred patients: comparison of retrospective and prospective studies.

OBJECTIVE: In this study the sensitivity and specificity of immunochemical tests for colorectal neoplasia were evaluated in retrospective and prospective studies. METHODS: Four types of fecal blood tests--a chemical test (Hemoccult II) and three different immunochemical tests including a test which detects hemoglobin and transferrin- were performed in the retrospective study. In the prospective study the test for hemoglobin and transferrin was used for all patients that underwent total colonoscopy. PATIENTS: One hundred seven patients with colorectal neoplasia, 57 with gastroduodenal bleeding, and 62 with normal digestive tracts were examined retrospectively. One thousand two hundred and ninety-eight nonspecifically symptomatic patients whose endoscopic examination was negative for hemorrhagic lesions in the upper digestive tract were examined prospectively. RESULTS: In the retrospective study, sensitivities for the detection of colorectal cancers and adenomas with diameters > or =10 mm using the tests which detect hemoglobin and transferrin were 98% and 89%, respectively. These were the highest sensitivity among the four tests. The specificity of this test was 97%, which was higher than that of the Hemoccult II test. In the prospective study, the sensitivities of the tests for hemoglobin and transferrin for the detection of colorectal cancers and adenomas with diameters > or =10 mm were 79% and 33%, respectively. The specificity was 95%. CONCLUSIONS: The test for hemoglobin and transferrin showed the highest sensitivity and specificity for colorectal neoplasia in the retrospective study. The sensitivity and specificity of this test were not so high in the prospective study, but they may be clinically applicable in the evaluation of patients with various nonspecific symptoms.

Adenoma↗
PubMed2000

Comparison of tests for fecal lactoferrin and fecal occult blood for colorectal diseases: a prospective pilot study.

OBJECTIVE: This prospective pilot study was conducted to compare the usefulness of measuring fecal lactoferrin (Lf) to that of fecal occult blood (FOB) test for detection of colorectal diseases. PATIENTS AND METHODS: The subjects were 351 patients who underwent colonoscopy. A fecal sample was obtained on the day before colonoscopy. Fecal Lf was measured by enzyme-linked immunosorbent assay. The FOB test was performed by combined assay (latex agglutination) of hemoglobin and transferrin. RESULTS: The specificities of the fecal Lf and FOB tests were the same (88.7%). For patients with colorectal cancer (13), colorectal polyp (69), ulcerative colitis (18), Crohn's disease (13), non-specific colitis (8), internal hemorrhoids (60), colon diverticulum (27), and miscellaneous diseases of the colon (10), the rates of positivity for fecal Lf were 7/13, 14/69, 12/18, 7/13, 4/8, 22/60, 8/27, and 6/10, respectively. The corresponding rates for FOB were 8/13, 12/69, 11/18, 4/13, 4/8, 9/60, 2/27, and 1/10. For patients with internal hemorrhoids, the rate of positivity for fecal Lf was significantly higher than that for FOB. In other disease groups, there was no significant difference in the rate of positivity between fecal Lf and FOB. CONCLUSION: These findings suggest that measurement of fecal Lf is as useful as FOB in detecting colorectal diseases.

Colonic Diseases↗
PubMed1999

RGS7 and RGS8 differentially accelerate G protein-mediated modulation of K+ currents.

The recently discovered family of RGS (regulators of G protein signaling) proteins acts as GTPase activating proteins which bind to alpha subunits of heterotrimeric G proteins. We previously showed that a brain-specific RGS, RGS8 speeds up the activation and deactivation kinetics of the G protein-coupled inward rectifier K+ channel (GIRK) upon receptor stimulation (Saitoh, O., Kubo, Y., Miyatani, Y., Asano, T., and Nakata, H. (1997) Nature 390, 525-529). Here we report the isolation of a full-length rat cDNA of another brain-specific RGS, RGS7. In situ hybridization study revealed that RGS7 mRNA is predominantly expressed in Golgi cells within granule cell layer of cerebellar cortex. We observed that RGS7 recombinant protein binds preferentially to Galphao, Galphai3, and Galphaz. When co-expressed with GIRK1/2 in Xenopus oocytes, RGS7 and RGS8 differentially accelerate G protein-mediated modulation of GIRK. RGS7 clearly accelerated activation of GIRK current similarly with RGS8 but the acceleration effect of deactivation was significantly weaker than that of RGS8. These acceleration properties of RGS proteins may play important roles in the rapid regulation of neuronal excitability and the cellular responses to short-lived stimulations.

Amino Acid Sequence↗
PubMed1999

Brain weight in autism: normal in the majority of cases, megalencephalic in rare cases.

The brain weights of 21 postmortem autism cases (5 new and 16 previously published) were compared with normal brain weights from six autopsy studies. Of the 21 cases, 17 had normal brain weights and 1 was micrencephalic. Compared with the normal median (1,460 g), three autism cases were megalencephalic: two (1,810 g and 1,820 g) had been previously reported and one (1,880 g) was a new case. Brain weight is thus normal in most postmortem cases of autism. There are, however, rare cases of megalencephaly and possibly micrencephaly.

Adolescent↗