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Biomedical subjects

T Nagata

Publications and source records attributed to T Nagata.

At least 109 records · Page 6Linked to original sources

High prevalence of spinocerebellar ataxia type 1 (SCA1) in an isolated region of Japan.

Autosomal dominant cerebeller ataxias (ADCAs) are a heterogeneous group of neurodegenerative disorders that differ in both the clinical manifestations and modes of inheritance. At present, eight different genes causing ADCAs have been found: spinocerebeller ataxia type 1 (SCA1), SCA2, SCA3/Machado-Joseph disease (MJD), SCA6, SCA7, SCA8, SCA12 and dentatorubropallidoluysian atrophy (DRPLA). The relative prevalence of each mutation varies according to race and native place. We studied 117 unrelated ADCA families that originated from the Tohoku District in the northernmost part of Honshu Island in Japan (mainly Miyagi Prefecture in the central part of Tohoku District). The SCA1 mutation was the most frequent among the known disorders (24.8% of all such families). The relative prevalence of SCA1 in the Tohoku District is very high compared with the values already reported from other regions in the world. Because the population of this area had seldom moved, the alleles with SCA1 mutations (including alleles with an intermediate CAG repeat number) are assumed to have been present in this area for a long time.

Ataxin-1↗

Two distinct components of initial glutamate release synchronized with anoxic depolarization in rat global brain ischemia.

Numerous reports have suggested that anoxic depolarization is a critical event in the pathogenesis of cerebral ischemia. Extracellular glutamate concentration ([Glu]e) is closely related to the pathogenesis of ischemia. Therefore, these pathogenic mechanisms merit study, especially the relationship between [Glu]e elevation and the ionic basis of early changes in membrane potential after ischemic insult in vivo. It is often presumed from electrophysiological studies that a causal relationship exists between impaired glutamate uptake and/or progressive glutamate increase and anoxic depolarization, but few in vivo reports have found any sign of a progressive increase of [Glu]e elevation preceding anoxic depolarization. Recently, we reported the application of an oxygen-independent real-time technique for monitoring glutamate levels in the extracellular space during in vivo ischemia, and demonstrated that the massive glutamate release during ischemia is biphasic. In the present study, using this real-time monitoring system, we carried out a more detailed analysis of the initial events in the first phase of glutamate release during ischemia-induced anoxic depolarization. The shape of the rising slope that forms the peak of the first phase suggested two components. The second component was approximately 10 times steeper than the first, with two different components of the rise on the way to the peak of the biphasic [Glu]e elevation. This is the first report to demonstrate these components of the initial glutamate peak, and suggests a progressive second component of the [Glu]e increase preceding Ca2+-dependent release from synaptic vesicles with anoxic depolarization, in vivo.

Animals↗

Synthesis and receptor sites of endothelin-1 in the rat liver vasculature.

Immunocytochemical localization of big endothelin-1 (big ET-1), ET-1, and ET receptor A and B (ET(A) and ET(B)), and gene expression of prepro ET-1 mRNA were examined on the rat liver vasculature. Immunoreactivities for big ET-1 and ET-1 were preferentially seen along the endothelium of interlobular veins (IV) and artery (IA), although the staining intensity was more pronounced in IV. Expression of preproET-1 mRNA was detected in both vascular endothelia and the signal intensity was more prevalent in IV. Immunoelectron microscopy showed that rough endoplasmic cisterns were immunoreactive for big ET-1, while Weibel-Palade (WP) bodies, a storage site for ET-1, were immunoreactive for ET-1 in endothelial cells of IV. These results indicate that endothelial cells of IV are the major site of synthesis of ET-1, which is extracellularly secreted by degranulation and/or exocytosis of WP bodies. Hepatic stellate cells (HSCs), especially of the plasma membrane of perisinusoidal and interhepatocellular processes, were immunoreactive for both ET(A) and ET(B) receptor antibodies. These findings suggest that ET-1 receptor-mediated HSC contraction is involved in the regulation of hepatic sinusoidal blood flow as previously cited in mammalian liver cirrhosis. We also showed that sarcolemma and caveoles in the smooth muscle cells of the media of IV, and its branches before reaching the hepatic sinusoids, were immunoreactive for ET(A) receptor antibody. The results suggest that such vessels, which contains a large amount of hepatic blood inflow, participate in pump mechanism toward hepatic sinusoidal circulation in a receptor-mediated paracrine fashion.

Animals↗

Multi-impulsivity of Japanese patients with eating disorders: primary and secondary impulsivity.

Several studies have noted that multi-impulsive bulimia nervosa tends to be refractory to treatment. However, it is not known whether these impulsivities are an expression of more fundamental psychopathology or simply the consequence of chaotic eating behaviors. Studies of the temporal relationship between the onset of eating disorder and the occurrence of impulsive behaviors will facilitate a better understanding of these issues. Subjects consisted of 60 patients with anorexia nervosa restricting type (AN-R), 62 patients with anorexia nervosa binge-eating/purging type (AN-BP), 114 patients with bulimia nervosa purging type (BN) and 66 control subjects. Impulsive behaviors and childhood traumatic experiences were assessed by self-report questionnaire. Multi-impulsivity (defined by at least three of the following: heavy regular alcohol drinking; suicide attempt; self-mutilation; repeated shoplifting of items other than food; sexual relationships with persons not well known to the subject) was found in 2% of AN-R, 11% of AN-BP, 18% of BN and 2% of control subjects. Eighty percent of BN patients with multi-impulsivity had a history of suicide attempts or self-mutilation history prior to the onset of bulimia nervosa. In BN patients, there tended to be a relationship between childhood parental loss or borderline personality disorder and multi-impulsivity. In conclusion, primary impulsivity (chronological prior occurrence of impulsive behaviors) does exist even in a very different culture, although the number of patients of this type is very limited.

Adult↗

Role of the JAK/STAT pathway in rat carotid artery remodeling after vascular injury.

In cultured vascular smooth muscle cells (VSMCs), Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) are expressed constitutively and play a role in angiotensin II (Ang II)-induced intracellular signaling and proliferation. However, little is known regarding the relevance of these proteins to the process of vascular remodeling. The role of JAK and STAT proteins in vascular remodeling and their functional coupling with Ang II were examined in balloon-injured rat carotid artery. Immunoreactive Jak2, Tyk2, Stat1, and Stat3 were not detected in the intact artery. Immunohistostaining showed transient expressions of these JAKs and STATs in medial and neointimal VSMCs at days 2 and 5, respectively, with a peak at day 7 in both layers. The expressions declined to insignificant levels by day 14. Ang II type 1 receptors (AT(1)s) were coexpressed in the medial and neointimal VSMCs expressing Jak2 and Stat3. The Jak2 and Stat3 inductions in the injured artery were accompanied by constitutive Jak2 and Stat3 phosphorylations, which were enhanced by ex vivo Ang II stimulation via AT(1). Additionally, a Jak2 inhibitor, AG490, blocked the Ang II-induced Stat3 phosphorylation. Furthermore, local treatment with AG490 inhibited constitutive Stat3 phosphorylation and neointimal VSMC replication and subsequently reduced neointima formation in the injured artery. In conclusion, JAK and STAT proteins were inducible in medial and neointimal VSMCs after vascular injury and were functionally coupled to AT(1). The inductions of JAKs and STATs would be involved in the mechanisms of neointima formation after vascular injury.

Animals↗

Lineage-specific regulation of the murine RAG-2 promoter: GATA-3 in T cells and Pax-5 in B cells.

Recombination activating gene-1 (RAG-1) and RAG-2 are expressed in lymphoid cells undergoing the antigen receptor gene rearrangement. A study of the regulation of the mouse RAG-2 promoter showed that the lymphocyte-specific promoter activity is conferred 80 nucleotide (nt) upstream of RAG-2. Using an electrophoretic mobility shift assay, it was shown that a B-cell-specific transcription protein, Pax-5, and a T-cell-specific transcription protein, GATA-3, bind to the -80 to -17 nt region in B cells and T cells, respectively. Mutation of the RAG-2 promoter for Pax-5- and GATA-3-binding sites results in the reduction of promoter activity in B cells and T cells. These results indicate that distinct DNA binding proteins, Pax-5 and GATA-3, may regulate the murine RAG-2 promoter in B and T lineage cells, respectively. (Blood. 2000;95:3845-3852)

Animals↗

Dietary intake of rapeseed oil or soybean oil as the only fat nutrient in spontaneously hypertensive rats and Wistar Kyoto rats - blood pressure and pathophysiology.

Spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) rats were fed a diet containing 10% rapeseed (canola) oil or soybean oil as dietary fat, and given drinking water containing 1% NaCl for 26 weeks. From the 10th week and later, systolic blood pressure in the canola oil group became higher than that in the soybean oil group in each strain. The 26-week feeding of canola oil increased plasma lipids and the neutrophil counts, and decreased the platelet counts. In the canola oil group the heart and kidney tended to become heavier with sporadically found histologic lesions. Acetylcholine- and nitroprusside-induced dilating responses of isolated aortic rings and norepinephrine- and veratridine-induced increases in vascular tone of isolated perfused mesenteric arteries were not different between the two groups in each strain. These results demonstrate that canola oil intake as the only dietary fat elevates blood pressure of the rat provided with drinking water containing 1% NaCl through mechanisms other than blunt dilating response of the blood vessel due to dysfunction of the endothelium or vascular smooth muscle, the augmented response to norepinephrine in the arteries and the increased amount of norepinephrine in the sympathetic nerve endings. The lesions in the heart and kidney in SHR may be related to a strain-specific peripheral vascular deterioration which was disclosed by the extremely high blood pressure in the canola oil group.

Acetylcholine↗

Quantitative evaluation of extracellular glutamate concentration in postischemic glutamate re-uptake, dependent on brain temperature, in the rat following severe global brain ischemia.

Changes in brain temperature are known to modulate the marked neuronal damage caused by an approximately 10-min intra-ischemic period. Numerous studies have suggested that the extracellular glutamate concentration ([Glu](e)) in the intra-ischemic period and the initial postischemia period is strongly implicated in such damage. In this study, the effects of intra-ischemic brain temperature (32, 37, 39 degrees C) on [Glu](e) were investigated utilizing a dialysis electrode combined with ferrocene bovine serum albumin (BSA), which allows oxygen-independent real-time measurement of [Glu](e). This system allowed separate quantitative evaluation of intra-ischemic biphasic glutamate release from the neurotransmitter and metabolic pools, and of postischemic glutamate re-uptake in ischemia-reperfusion models. The biphasic [Glu](e) elevation in the intra-ischemic period did not differ markedly among intra-ischemic brain temperatures ranging from 32 to 39 degrees C. Intra-ischemic normothermia (37 degrees C) and mild hyperthermia (39 degrees C) markedly inhibited [Glu](e) re-uptake during the postischemic period, although the intra-ischemic [Glu](e) elevation did not differ from that during intra-ischemic hypothermia (32 degrees C). It was assumed that normothermia or mild hyperthermia in the intra-ischemic period influences intracellular functional abnormalities other than the intra-ischemic [Glu](e) elevation, thereby inhibiting glutamate re-uptake after reperfusion rather than directly modulating intra-ischemic [Glu](e) dynamics.

Animals↗

A lectin from an edible mushroom Pleurotus ostreatus as a food intake-suppressing substance.

In an experiment in which rats were allowed free access to food and water, the rats did not eat the diet containing a mushroom Pleurotus ostreatus even if they were emaciated. A P. ostreatus lectin (POL) was isolated from the mushroom as the food intake-suppression principle. In hemagglutination inhibition assays, Me-alphaGalNAc was the most potent inhibitor among the monosaccharides tested. Among all the sugars tested, 2'-fucosyllactose (Fucalpha1-->2Galbeta1-->4Glc) was the strongest inhibitor and its inhibitory potency was five times greater than that of Me-alphaGalNAc. POL exhibited a binding ability to bovine submaxillary mucin (BSM) and asialo-BSM and the other glycoproteins were inert to the binding. The food intake-suppressing activity of POL was dependent on the dose. The diet containing 0.1% POL caused a 50% decrease in the food intake of rats against the control.

Amino Acids↗

Advantage of gene gun-mediated over intramuscular inoculation of plasmid DNA vaccine in reproducible induction of specific immune responses.

Utilizing a plasmid DNA encoding a single cytotoxic T lymphocyte (CTL) epitope and that encoding ovalbumin (OVA), we compared the reproducibility in the induction of immune responses by gene gun and intramuscular immunization. As compared to intramuscular inoculation, gene gun DNA immunization appeared to bring about highly reproducible and reliable results in the induction of specific CTL and IFN-gamma production to the CTL epitope and production of anti-OVA IgG. The results obtained by intramuscular inoculation vary significantly. Our data shown here strongly suggest that gene gun immunization of skin is a much more reliable method for DNA vaccination to induce effective immune responses in an animal model.

Animals↗

Cyclosporin A decreases the degradation of type I collagen in rat gingival overgrowth.

Cyclosporin A (CsA) is used as an immunosuppressive agent and its prominent side effect is the induction of fibrous gingival overgrowth. The purpose of this study was to investigate the effect of CsA on the type I collagen metabolism in the gingiva of rats fed a powdered diet either containing or lacking CsA. Immunohistochemical analysis revealed that type I collagen was more prevalent in the connective tissue of CsA-treated gingiva than in those of control rats on days 15, 30, and 55 after the start of feeding. Total RNAs were isolated from mandibular molar gingiva on days 0, 3, 8, 15, 30, and 55. Quantitative analysis of mRNA by reverse transcriptase-polymerase chain reaction revealed that the CsA-treated groups showed a gradual decrease in expression of type I collagen and collagenase mRNAs, 0.4% and 18.0% on day 55 compared with those on day 0, respectively. In the control groups, type I collagen and collagenase mRNAs also decreased to 19.7% and 63.0%, respectively, however, both mRNA expressions were significantly lower in the CsA-treated group than in the controls. An electron microscopic analysis of fibroblasts was performed to count the number of cells with collagen fibrils in the cytoplasm, a marker of phagocytosis of collagen by fibroblasts. The collagen fibrils were detected in 4.7% +/- 2.7% and 24.3% +/- 13.7% of fibroblasts in the overgrown gingiva treated with CsA rat for 8 days and 30 days, but in 57.0% +/- 5.3% and 81.3% +/- 9.2% of fibroblasts in the each control group gingiva, respectively. Furthermore, in vitro analysis was performed to measure the phagocytosis of cultured fibroblasts by flow cytometry using collagen-coated latex beads. Fibroblasts isolated from CsA-treated gingiva on day 8 and day 30 contained 5.7% +/- 0.6% and 9.9% +/- 1.5% phagocytic cells, whereas control fibroblasts contained 50.3% +/- 5.5% and 33.3% +/- 4.9% phagocytic cells, respectively. The inhibition rate of phagocytic activity was similar between in vivo and in vitro assays. These findings suggest that the decrease of the collagen degradation due to the lower phagocytosis and the lower collagenase mRNA expression are closely associated with the increase of type I collagen accumulation in CsA-treated rat gingiva.

Animals↗

Multi-impulsivity among bulimic patients in Japan.

OBJECTIVE: Studies in Western world patients suggest the possible existence of a subgroup of patients with bulimia nervosa (BN) who display multiple problems with impulsivity, such as suicidal attempts. We assessed impulsive behaviors among BN patients in Japan to discuss them crossculturally. METHOD: Impulsive behaviors in 64 BN patients were assessed and multi-impulsivity (MI) was defined according to the definition proposed by Fichter, Quadflieg, and Rief (Psychological Medicine, 24, 591-604,1994). RESULTS: Nineteen patients (30%) met the definition of MI. BN patients with MI had more severe clinical features, such as concurrent depressive and anxious symptoms, global functioning, and higher prevalence of borderline personality disorder than BN patients without MI. DISCUSSION: These results showed the similarities between BN patients with MI in Japan and those patients in the Western world in clinical and psychopathological characteristics and a life-time incidence of each impulsive behavior. These findings may suggest culturally free bases for linkage between BN and MI.

Adult↗

Alteration of protein composition in mouse thymocytes by signals through T-cell receptor.

To avoid destructive autoimmunity, T-cell precursors (thymocytes) expressing autoreactive T-cell receptor are deleted in the thymus via an apoptotic process by the signals from the T-cell receptor-CD3 complexes. In order to analyze the apoptotic mechanism, we established a cell-free system using the lysates from mouse thymocytes treated in vivo with anti-CD3 monoclonal antibody (mAb). The soluble cytosolic high molecular mass protein fraction from the anti-CD3-treated thymocytes revealed an activity that directly induces nuclear apoptotic morphological changes and DNA fragmentation. This fragmentation activity was not observed in the fraction from the thymocytes without anti-CD3 treatment. Proteins in both fractions were separated by two-dimensional electrophoresis. The silver-stained gels revealed differences in protein spots. These protein spots were identified by database searching of mass spectrometric (MS) and tandem mass spectrometric (MS/MS) data obtained from in-gel tryptic digests of the spots, using an integrated system of liquid chromatography/electrospray ionization/ion-trap mass spectrometry. In this study, the high mobility group protein HMG2 was identified as one of the cytosolic proteins that is increased by the signals from the T-cell receptor, and heterogeneous nuclear ribonucleoprotein A2/B1 and glyceraldehyde 3-phosphate dehydrogenase were found to be decreased by the signals.

Amino Acid Sequence↗

A case of monoclonal gammopathy associated with acute myelomonocytic leukemia with eosinophilia suggested to be the result of lineage infidelity.

Acute myelomonocytic leukemia (AMMoL) accompanied by monoclonal gammopathy is a rare condition, and its pathogenesis and the cytogenetic mechanism of such leukemogenesis have not been determined in detail. A case of AMMoL with eosinophilia accompanied by immunoglobulin G kappa monoclonal gammopathy is described. Immunophenotypic studies of the peripheral blood and bone marrow mononuclear cells revealed no evidence of abnormally proliferating cells of B-lineage. DNA analyses of bone marrow mononuclear cells containing leukemic cells revealed rearrangement of the kappa-light chain (Igkappa) gene and c-myc and c-jun proto-oncogenes. The intensities of the rearranged bands for these genes on Southern blot analysis suggested the existence of a major population of leukemic cells with rearranged Igkappa gene and minor population(s) of leukemic cells with rearranged c-myc and/or c-jun proto-oncogene(s) in the patient's bone marrow and indicated the occurrence of genetic evolutionary changes in leukemic cells in this patient before starting chemotherapy. These results suggest that these leukemic cells are the most likely candidate for immunoglobulin G kappa monoclonal protein production, and structural abnormalities of c-myc and c-jun proto-oncogenes may have contributed to the evolution of leukemic cells in this patient.

Blotting, Southern↗

The high level of hCDC10 gene expression in neuroblastoma may be associated with favorable characteristics of the tumor.

BACKGROUND: The biological behavior of neuroblastomas detected through mass screening (MS, </=1 year of age) and that of mass screening-negative later-presenting (MSN, >1 year of age) neuroblastomas have been reported to differ in many studies. To investigate the biological differences between these two groups, we analyzed the differences in mRNA profiles. MATERIALS AND METHODS: We analyzed the mRNA profiles of MS and MSN neuroblastomas using differential display, and cloned and sequenced the bands differentially expressed between these two groups. Using the RNA analysis by polymerase chain reaction (RNA-PCR) method, the relative amount of mRNA in tumor tissue in each sample was measured. Associations between relative amount of mRNA and clinical and genetic variables related to patient prognosis and the effect of the level of mRNA expression on survival probability were investigated using statistical methods. RESULTS: Using differential display and RNA-PCR, we found that the mRNA for the human homologue of the yeast cdc10 gene (hCDC10) identified in Saccharomyces cerevisiae was expressed at a higher level in the MS group of patients than in the MSN group of patients (0.554 +/- 0.197 for MS neuroblastoma, n = 24 and 0.244 +/- 0.179 for MSN neuroblastoma, n = 10, P < 0.01), and this difference was suggested to be independent of the histologic subtype of tumor. A high level of hCDC10 mRNA expression in neuroblastomas (relative amount of hCDC10 mRNA > 0.35) was also suggested to be associated with younger age at diagnosis (</=1 year of age, P < 0.01), favorable clinical stage (I, II, and IVs, P < 0. 01), and favorable histology in the Shimada classification (P < 0. 01), whereas a low level of hCDC10 mRNA expression (relative amount of hCDC10 mRNA </=0.35) was suggested to be associated with the progression of clinical stage (P < 0.01) and N-myc gene amplification (>1 copy, P < 0.05). Patients with neuroblastomas with a high level of hCDC10 mRNA expression were suggested to have a better prognosis than those with a low level of hCDC10 mRNA expression (P < 0.01). CONCLUSIONS: A high level of hCDC10 mRNA expression in neuroblastomas may be associated with favorable clinical and biological characteristics, and the expression of hCDC10 mRNA in neuroblastomas may affect the clinical and biological characteristics of this type of tumor.

Cell Cycle Proteins↗

Impaired expression of MHC class I molecules on mouse testicular germ cells is mainly caused by the post-transcriptional mechanism.

In this study, we examined expression of the major histocompatibility complex (MHC) class I molecules and of the mRNAs for MHC class I-mediated antigen presentation machinery molecules in highly purified C57BL/6 mouse testicular germ cells. Although H2 class I molecules were not detected on the cell surface, small amounts of the molecules were detected inside the cells by flow cytometric and immunoprecipitation analyses. Interferon (IFN)gamma treatment did not affect expression of the molecules on the surface by flow cytometric analysis. In addition, expression of mRNAs for MHC class I-mediated antigen presentation machinery molecules in the germ cells was analyzed by reverse transcription-polymerase chain reaction analysis. The faint constitutive expression of mRNAs for H2-K, beta2-microglobulin (beta2m), tapasin, and calnexin was observed in the cells. IFNgamma treatment up-regulated expression of mRNAs for H2-K, beta2m, TAP1 (a peptide transporter), and LMP2 (a proteosomal subunit). These findings indicate that impaired expression of MHC class I molecules on the cell surface of mouse testicular germ cells is mainly caused by the post-transcriptional regulatory mechanism.

Animals↗

Detection of aberrations of 17p and p53 gene in gastrointestinal cancers by dual (two-color) fluorescence in situ hybridization and GeneChip p53 assay.

We performed dual (two-color) fluorescence in situ hybridization (FISH) using direct fluorescent labeling probes for p53 and chromosome 17 in six gastrointestinal (3 stomach and 3 colon) cancers. In three of these (1 stomach and 2 colon) the interphase cell nuclei showed an imbalance of signals for the p53 and chromosome 17; that is, the p53 signal count was lower than the chromosome 17 signal count, indicating deletion of the p53 gene. Moreover, metaphase FISH analysis demonstrated that those nuclei actually had a chromosome 17 with deletion of the p53 gene. Interestingly, these three cases had an abnormal chromosome 17 copy number, that is, chromosome 17 aneusomy. Furthermore, to investigate the possibility of p53 mutation in tumors with an imbalance of signals for chromosome 17 and p53 per nucleus, we performed a GeneChip p53 assay which has recently been developed. GeneChip p53 assay demonstrated that a primary tumor sample from one colon cancer case had a heterozygous point mutation of CGT (Arg) to CAT (His) at codon 273 in exon 8. In addition, a sample of metastatic tumor in the liver from the same case revealed two heterozygous point mutations. One of them was the same mutation as that is the primary tumor; the other was GTG (Val) to GGG (Gly) at codon 217 in exon 6. In conclusion, we found that the combination of dual-color FISH and GeneChip p53 assay offered reliable results and important information concerning not only deletion of the p53 gene and chromosome 17 aneusomy but also p53 mutations. Using these techniques, we demonstrated that an imbalance of signals for chromosome 17 and p53 per nucleus, chromosome 17 aneusomy, and accumulation of p53 mutations had occurred during carcinogenesis and development of gastrointestinal cancers.

Centromere↗

New ocular movement detector system as a communication tool in ventilator-assisted Werdnig-Hoffmann disease.

A non-contact communication system was developed for a ventilator-assisted patient with Werdnig-Hoffmann disease who had lost all voluntary movements except for those of the eye. The system detects the extraocular movements and converts them to either a 'yes' signal (produced by one lateral eyeball movement) or a 'no' signal (produced by two successive lateral eyeball movements) using a video camera placed outside the patient's visual field. The patient is thus able to concentrate on performing a task without any intrusion from the detection system. Once the setting conditions of the device have been selected, there is no need for any resetting, as the patient is unable to move his body. In addition to playing television games, the child can use the device to select television channels, compose music, and learn written Japanese and Chinese characters. This seems to broaden the patient's daily world and promote mental development.

Activities of Daily Living↗