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Biomedical subjects

M Itoh

Publications and source records attributed to M Itoh.

At least 271 records · Page 15Linked to original sources
PubMed1999

Cerebrospinal fluid levels of amyloid beta-peptide1-42, but not tau have positive correlation with brain glucose metabolism in humans.

To address the question of whether assay for cerebrospinal fluid (CSF) levels of amyloid beta-peptide 1-42 (A(beta)1-42) and tau allow us to monitor the neurodegenerative processes that lead to a progressive and massive death of neurons in Alzheimer's disease (AD) and non-AD patients, cerebral glucose metabolism using 2-[18F] fluoro-2-deoxy-glucose was quantified by positron emission tomography in fifteen AD patients and nine non-AD patients with defined levels of CSF-A(beta)1-42 and CSF-tau. The CSF-A(beta)1-42 levels, but not the CSF-tau levels, in both AD and non-AD patients consistently and significantly correlated with global and, in particular, temporal lobe glucose metabolism. Results from our study suggest that the CSF-A(beta)1-42 levels may reflect residual brain function and help monitoring progression of dementing disorders.

Aged↗
PubMed1999

Developmental and age-related changes of dopamine transporter, and dopamine D1 and D2 receptors in human basal ganglia.

The developmental and age-related changes of the dopamine transporter (DAT), and the dopamine D1 and D2 receptor (D1R and D2R) subtypes were investigated in basal ganglia (BG) of human brain. DAT immunostaining was mainly observed in the neuropil, neurons, and glia of the striatum. The DAT-positive neuropil was detectable at 32 GW, a peak being reached at 9-10 years of age, with a decrease to 50-63 years of age. The developmental pattern of DAT immunoreactivity in neuron was similar to that of the neuropil. DAT-positive glia were observed in the BG at 32 GW, which increased slightly at 38-40 GW, and then did not obviously change until 6-8 months after birth. D2R-positive neurons were clearly observed at 19 GW, a peak being reached at 32 GW and 1-3 months of age in the globus pallidus and striatum, respectively, with a decrease after 9-10 years of age. D1R was expressed as early as D2R, but decreased after 6-8 months. Our results suggest that D1R and D2R expression is an intrinsic property of striatal neurons and is independent of dopaminergic innervation. D1R may play a more important role in neuronal maturation of the BG than D2R. D2R may be closely correlated with late neuronal development. The higher expression of DAT during adolescence may be related to function of the BG which learns complex behavioral patterns. The significance of the age-related decreases in DAT, D1R and D2R in the BG remains to be further investigated.

Adolescent↗
PubMed1999

Brain-derived neurotrophic factor prevents neuronal cell death induced by corticosterone.

Corticosterone (CORT), one of the glucocorticoids, causes neuronal damage in the hippocampus, but the mechanism(s) of action underlying its effects remains unknown. Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor that belongs to the neurotrophin family, affects the survival and/or differentiation of various types of neurons in vitro, and is able to antagonize neuronal death induced by various brain insults or neurotoxins in vivo. In this study, the effects of CORT on BDNF protein contents and mRNA expression were investigated in relation to neuronal survival/death of cultured rat hippocampal neurons, because the colocalization of BDNF with its receptor, TrkB, suggests that BDNF may exert its putative protective and trophic effects through an autocrine mechanism in the hippocampus. Administration of CORT accelerated the neuronal death that proceeds after serum deprivation, and simultaneously reduced the levels of BDNF mRNA and intracellular BDNF content. Exogenously added BDNF actually attenuated CORT-induced neuronal death, but not in the presence of K252a, an inhibitor of the tyrosine kinase activity of Trk family receptors. These observations suggest that CORT induces damage to hippocampal neurons, at least partly, via reducing their BDNF synthesis.

Animals↗
PubMed1999

A novel peroxisomal enzyme, D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein: its expression in the developing human brain.

D-bifunctional protein, which is a newly recognized peroxisomal enzyme (D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase), demonstrates a characteristic development of pattern in the human brain. At 13 gestational weeks (GW), D-bifunctional protein immunoreactivity first appeared in the brain. Each neuron exhibited increased immunoreactivity along with growth in size as age increased and size with age. Glial cells in the white matter showed immunoreactivity after 30 GW. On the other hand, the L-bifunctional protein immunoreactivity was reported in neurons from 23 or 25 GW and in the white matter from 12 or 14 GW. Because of polymicrogyria in conditions such as infantile Refsum disease and infantile adrenoleukodystrophy, peroxisomal enzymes are thought to play an important role in neuronal migration and possibly myelination. D-bifunctional protein may be relevant to neuronal migration and L-bifunctional protein may be involved in axonal growth and synaptic development. This study is designed to access the ontogeny of D-bifunctional protein in the human brain.

17-Hydroxysteroid Dehydrogenases↗
PubMed1999

Reciprocal changes in the expression of Bcl-2 and Bax in hypoglossal nucleus after axotomy in adult rats: possible involvement in the induction of neuronal cell death.

Numerous studies of neonatal neuronal development in mammals have revealed that neuronal cell death following axotomy is apoptotic in nature. In adult animals, however, neuronal cell death following axonal injury may or may not exhibit features of apoptosis. Bcl-2 and Bax have been identified as inhibitor and promoter proteins, respectively, of apoptosis. To investigate the relationship between these proteins and neuronal cell death following axotomy in adult animals, we performed axotomy of the right hypoglossal nerve in adult male Wistar rats, and sacrificed the rats at various intervals after axotomy. We analyzed the expression of Bcl-2 and Bax immunohistochemically in the hypoglossal nuclei of the adult rats following axotomy. Our analysis showed an increase in the percentage of Bax-positive motoneurons relative to the total number of motoneurons in the hypoglossal nucleus on the axotomy side at three days after axotomy. In contrast, a low percentage of Bcl-2-positive motoneurons to the total number of motoneurons was noted at the same time interval after axotomy. Quantitative analysis of the signal intensity for Bcl-2 and Bax in individual neurons showed that Bax immunostaining significantly increased 7 days after axotomy, while the intensity of Bcl-2 immunostaining decreased in most of Bcl-2-positive neurons. Our results confirmed the occurrence of motoneuron cell death in adult rats after axotomy, and that a close temporal relationship exists between the reciprocal changes in Bcl-2/Bax expression and the loss of motoneurons. These results indicate the possible involvement of the Bcl-2/Bax system in the induction of neuronal cell apoptosis after axotomy in adult rats.

Age Factors↗
PubMed1999

Thymus and autoimmunity: production of CD25+CD4+ naturally anergic and suppressive T cells as a key function of the thymus in maintaining immunologic self-tolerance.

This study shows that the normal thymus produces immunoregulatory CD25+4+8- thymocytes capable of controlling self-reactive T cells. Transfer of thymocyte suspensions depleted of CD25+4+8- thymocytes, which constitute approximately 5% of steroid-resistant mature CD4+8- thymocytes in normal naive mice, produces various autoimmune diseases in syngeneic athymic nude mice. These CD25+4+8- thymocytes are nonproliferative (anergic) to TCR stimulation in vitro, but potently suppress the proliferation of other CD4+8- or CD4-8+ thymocytes; breakage of their anergic state in vitro by high doses of IL-2 or anti-CD28 Ab simultaneously abrogates their suppressive activity; and transfer of such suppression-abrogated thymocyte suspensions produces autoimmune disease in nude mice. These immunoregulatory CD25+4+8- thymocytes/T cells are functionally distinct from activated CD25+4+ T cells derived from CD25-4+ thymocytes/T cells in that the latter scarcely exhibits suppressive activity in vitro, although both CD25+4+ populations express a similar profile of cell surface markers. Furthermore, the CD25+4+8- thymocytes appear to acquire their anergic and suppressive property through the thymic selection process, since TCR transgenic mice develop similar anergic/suppressive CD25+4+8- thymocytes and CD25+4+ T cells that predominantly express TCRs utilizing endogenous alpha-chains, but RAG-2-deficient TCR transgenic mice do not. These results taken together indicate that anergic/suppressive CD25+4+8- thymocytes and peripheral T cells in normal naive mice may constitute a common T cell lineage functionally and developmentally distinct from other T cells, and that production of this unique immunoregulatory T cell population can be another key function of the thymus in maintaining immunologic self-tolerance.

Animals↗
PubMed1999

Functional domains of alpha-catenin required for the strong state of cadherin-based cell adhesion.

The interaction of cadherin-catenin complex with the actin-based cytoskeleton through alpha-catenin is indispensable for cadherin-based cell adhesion activity. We reported previously that E-cadherin-alpha-catenin fusion molecules showed cell adhesion and cytoskeleton binding activities when expressed in nonepithelial L cells. Here, we constructed deletion mutants of E-cadherin-alpha-catenin fusion molecules lacking various domains of alpha-catenin and introduced them into L cells. Detailed analysis identified three distinct functional domains of alpha-catenin: a vinculin/alpha-actinin-binding domain, a ZO-1-binding domain, and an adhesion-modulation domain. Furthermore, cell dissociation assay revealed that the fusion molecules containing the ZO-1-binding domain in addition to the adhesion-modulation domain conferred the strong state of cell adhesion activity on transfectants, although those lacking the ZO-1-binding domain conferred only the weak state. The disorganization of actin-based cytoskeleton by cytochalasin D treatment shifted the cadherin-based cell adhesion from the strong to the weak state. In the epithelial cells, where alpha-catenin was not precisely colocalized with ZO-1, the ZO-1-binding domain did not completely support the strong state of cell adhesion activity. Our studies showed that the interaction of alpha-catenin with the actin-based cytoskeleton through the ZO-1-binding domain is required for the strong state of E-cadherin-based cell adhesion activity.

Animals↗
PubMed1999

Gab-family adapter proteins act downstream of cytokine and growth factor receptors and T- and B-cell antigen receptors.

We previously found that the adapter protein Gab1 (110 kD) is tyrosine-phosphorylated and forms a complex with SHP-2 and PI-3 kinase upon stimulation through either the interleukin-3 receptor (IL-3R) or gp130, the common receptor subunit of IL-6-family cytokines. In this report, we identified another adapter molecule (100 kD) interacting with SHP-2 and PI-3 kinase in response to various stimuli. The molecule displays striking homology to Gab1 at the amino acid level; thus, we named it Gab2. It contains a PH domain, proline-rich sequences, and tyrosine residues that bind to SH2 domains when they are phosphorylated. Gab1 is phosphorylated on tyrosine upon stimulation through the thrombopoietin receptor (TPOR), stem cell factor receptor (SCFR), and T-cell and B-cell antigen receptors (TCR and BCR, respectively), in addition to IL-3R and gp130. Tyrosine phosphorylation of Gab2 was induced by stimulation through gp130, IL-2R, IL-3R, TPOR, SCFR, and TCR. Gab1 and Gab2 were shown to be substrates for SHP-2 in vitro. Overexpression of Gab2 enhanced the gp130 or Src-related kinases-mediated ERK2 activation as that of Gab1 did. These data indicate that Gab-family molecules act as adapters for transmitting various signals.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Characterization of ZO-2 as a MAGUK family member associated with tight as well as adherens junctions with a binding affinity to occludin and alpha catenin.

ZO-2, a member of the MAGUK family, was thought to be specific for tight junctions (TJs) in contrast to ZO-1, another MAGUK family member, which is localized at TJs and adherens junctions (AJs) in epithelial and nonepithelial cells, respectively. Mouse ZO-2 cDNA was isolated, and a specific polyclonal antibody was generated using corresponding synthetic peptides as antigens. Immunofluorescence microscopy with this polyclonal antibody revealed that, similarly to ZO-1, in addition to TJs in epithelial cells, ZO-2 was also concentrated at AJs in nonepithelial cells such as fibroblasts and cardiac muscle cells lacking TJs. When NH2-terminal dlg-like and COOH-terminal non-dlg-like domains of ZO-2 (N-ZO-2 and C-ZO-2, respectively) were separately introduced into cultured cells, N-ZO-2 was colocalized with endogenous ZO-1/ZO-2, i.e. at TJs in epithelial cells and at AJs in non-epithelial cells, whereas C-ZO-2 was distributed along actin filaments. Consistently, occludin as well as alpha catenin directly bound to N-ZO-2 as well as the NH2-terminal dlg-like portion of ZO-1 (N-ZO-1) in vitro. Furthermore, immunoprecipitation experiments revealed that the second PDZ domain of ZO-2 was directly associated with N-ZO-1. These findings indicated that ZO-2 forms a complex with ZO-1/occludin or ZO-1/alpha catenin to establish TJ or AJ domains, respectively.

Animals↗
PubMed1999

IgG subclass switching is associated with the severity of experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein peptide in NOD mice.

We have recently shown that a single dose of the myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 produces a relapsing-remitting demyelinating disease similar to multiple sclerosis (MS) in Lewis rats. In this study we have assessed the possibility that a subclass of anti-MOG35-55 antibodies influences the clinical outcome of these diseases by examining the classes and isotypes of anti-MOG35-55 antibody produced during the course of MOG35-55-induced demyelinating disease in NOD mice. Following immunization, 7 of the 21 injected mice had only mild diseases, while the 14 others had severe progressive and/or relapsing-remitting diseases. There were no differences in anti-MOG35-55 IgG, IgA, IgM, IgG1, IgG2a, and IgG3 antibody titers between the severe and mild symptoms groups. High levels of IgG2b antibody to MOG35-55 were detected in all mice with severe symptoms. In contrast, none of the mice which contracted a mild disease produced anti-MOG35-55 IgG2b. These results suggest that in NOD mice, the IgG2b antibody response to MOG35-55 is associated with the severity of this MS-like demyelinating disease.

Amino Acid Sequence↗
PubMed1999

Normal development of mice and unimpaired cell adhesion/cell motility/actin-based cytoskeleton without compensatory up-regulation of ezrin or radixin in moesin gene knockout.

Ezrin/radixin/moesin (ERM) proteins are general cross-linkers between the plasma membrane and actin filaments. Because their expression is regulated in a tissue-specific manner, each ERM protein has been proposed to have unique functions. On the other hand, experiments at the cellular level and in vitro have suggested their functional redundancy. To assess the possible unique functions of ERM proteins in vivo, the moesin gene located on the X chromosome was disrupted by gene targeting in embryonic stem cells. Male mice hemizygous for the mutation as well as homozygous females were completely devoid of moesin but developed normally and were fertile, with no obvious histological abnormalities in any of the tissues examined. In the tissues of the mutant mice, moesin completely disappeared without affecting the expression levels or subcellular distribution of ezrin and radixin. Also, in platelets, fibroblasts, and mast cells isolated from moesin-deficient mice, targeted disruption of the moesin gene did not affect their ERM-dependent functions, i.e. platelet aggregation, stress fiber/focal contact formation of fibroblasts, and microvillar formation of mast cells, without compensatory up-regulation of ezrin or radixin. These findings favor the notion that ERM proteins are functionally redundant at the cellular as well as the whole body level.

Actins↗
PubMed1999

Differential behavior of E-cadherin and occludin in their colocalization with ZO-1 during the establishment of epithelial cell polarity.

At the initial stage of cell-cell contact of epithelial cells, primordial spot-like junctions are formed at the tips of thin cellular protrusions radiating from adjacent cells, where E-cadherin and ZO-1 are precisely coconcentrated (Yonemura et al., 1995, J. Cell Sci. 108:127-142). In fully polarized epithelial cells, E-cadherin and ZO-1 are completely sorted into belt-like adherens junctions (AJ) and tight junctions (TJ), respectively. Here we examined the behavior of occludin, an integral membrane protein consisting of TJ, during the establishment of epithelial cell polarity. Using confocal immunofluorescence microscopy, we quantitatively compared the spatial relationship of occludin/ZO-1 with that of E-cadherin/ZO-1 during epithelial cellular polarization by replating or wounding cultured mouse epithelial cells (MTD1-A). At the initial stage of cell-cell contact, E-cadherin and ZO-1 appeared to be simultaneously recruited to the primordial form of spot-like junctions at the tips of cellular processes which showed no concentration of occludin. Then, as cellular polarization proceeded, occludin was gradually accumulated at the ZO-1-positive spot-like junctions to form belt-like TJ, and in a complementary manner E-cadherin was sorted out from the ZO-1-positive spot-like junctions to form belt-like AJ. The molecular mechanism of TJ/AJ formation during epithelial cellular polarization is discussed with special reference to the roles of ZO-1.

Animals↗
PubMed1999

Intracellular mechanisms of hydrogen peroxide-mediated neutrophil adherence to cultured human endothelial cells.

We examined which endothelial second messengers are involved in peroxide-mediated endothelial-neutrophil adhesion with respect to endothelial P-selectin expression and platelet-activating factor (PAF). Peroxide (0.5 mM)-mediated adhesion was blocked by a protein kinase C (PKC) inhibitor, Gö6976 (10 nM); an intracellular calcium chelator, TMB-8 (0.1 mM); and a protein kinase G (PKG) inhibitor, KT5823 (0.5 microM); but not by a tyrosine kinase inhibitor, genistein (1 microM), or a protein kinase A inhibitor, H-89 (0.1 microM). These data were consistent with the proadhesive effects of PMA (0.1 microM), a PKC activator; a calcium ionophore, A23187 (1 microM); and dibutyryl cGMP (0.5 and 1 mM); but not phenylarsine oxide (0.1 mM), a tyrosine phosphatase inhibitor, or dibutyryl cAMP (1 mM). Conversely, peroxide-mediated P-selectin expression was blocked by Gö6976 and KT5823, but not by TMB-8. These data are strengthened by the observation that PMA and dibutyryl cGMP, but not A23187, increased P-selectin expression. WEB 2086 (10 microM), a PAF-receptor antagonist, blocked peroxide-, PMA-, and A23187-mediated adhesion, but not peroxide-mediated P-selectin expression. PAF itself (10 nM) stimulated adhesion, but not P-selectin expression. These data indicate that PKC and PKG are involved in peroxide-mediated neutrophil adhesion via P-selectin mobilization and PAF synthesis; however, intracellular calcium appears to mediate adhesion only through PAF synthesis.

Azepines↗
PubMed1999

Impaired pancreatic exocrine function in rats with carbon tetrachloride-induced liver cirrhosis.

BACKGROUND: Substantial numbers of studies have revealed the close correlation between chronic pancreatitis and cirrhosis in human. However, the situation with regard to pancreatic enzyme secretion is less clear. AIM: The aim of the study was to investigate pancreatic exocrine function in rats with carbon tetrachloride-induced liver cirrhosis in rats. METHODS: Pancreatic exocrine function and morphology in Sprague-Dawley rats with carbon tetrachloride-induced liver cirrhosis were investigated. Pancreatic exocrine functions stimulated by cholecystokinin-8 and other secretagogs were assessed in isolated pancreatic acini, and in vivo and morphological changes were studied by routine histological examination and electron microscopy. RESULTS: The basal and cholecystokinin-8-stimulated amylase releases from acini and acinar amylase content were significantly lower in the cirrhotic rats than the control. None of the secretagogs induced the some amount of amylase release in cirrhotic as in control rats. Volume of the pancreatic juice and outputs of amylase and protein were significantly decreased under basal and cholecystokinin-8-stimulated conditions in vivo. Electron microscopy revealed most of the rough-surfaced endoplasmic reticulum accompanying less numbers of ribosomes to be dilated and some mitochondria to be swollen in cirrhotic rats. CONCLUSION: Pancreatic exocrine functions are decreased in cirrhotic rats owing to alterations at the electron microscopic levels, reflecting an impaired acinar intracellular messenger system.

Amylases↗
PubMed1999

Easy detection of tumor in oncologic whole-body PET by projection reconstruction images with maximum intensity projection algorithm.

Whole-body PET scanning for an oncology study produces a large number of transaxial images by data acquisition over multiple bed positions. The sagittal and coronal reformatted images are often used for better understanding of radioisotope distribution. We reduced the number of PET images by calculating projection images and evaluated the merit of additional data processing for the visualization and detection of tumors. After reconstructing whole-body 18F-FDG PET images (6-8 bed positions) of eight cancer patients, antero-posterior and lateral projection images were calculated by the maximum intensity projection (MIP) algorithm, the standard deviation projection (SD) algorithm and the summed voxel projection (SUM) algorithm. The projection images were compared with 2D whole-body images for visualizing foci. The focal uptakes of various positions in original whole-body PET data (294-392 transaxial images) were visualized on only two MIP reformatted images when superimposition of hot spots did not occur. Even if one hot spot was superimposed over the other hot spot, we could recognize the existence of at least one focus and determine the true positions of the hot spots from corresponding transaxial images. The SD image was found inferior for showing a contrast of small foci to the corresponding MIP images in the neck, mediastinum and abdomen. The SUM image failed to visualize many metastatic lesions. MIP is a promising technique for the easy preliminary assessment of tumor distribution in oncologic whole-body PET study.

Algorithms↗
PubMed1999

Analysis of Th1 and Th2 cytokine production by peripheral blood mononuclear cells as a parameter of immunological dysfunction in advanced cancer patients.

PURPOSE: The presence of immunological dysfunction has not been well demonstrated in cancer patients. Recent studies have revealed that the immune response can be classified into types 1 and 2, and in the present work the immunological function of patients was studied from the perspective of these two types of response. METHODS: Types 1 and 2 immune response were evaluated by monitoring the production of various cytokines by peripheral blood mononuclear cells from 38 patients with advanced cancer of various organs and 20 healthy subjects. The usual immunological parameters, differential cell leukocyte counts, the level of T cell subsets (CD4 and CD8) and natural killer activity were also examined. RESULTS: The production of interleukin-2 (IL-2), interferon gamma, IL-10, IL-12 and tumor necrosis factor alpha was found to be significantly lower in the patients (75 +/- 57, 171 +/- 205, 40 +/- 34, 8 +/- 8, 1450 +/- 1010 pg/ml) than in healthy subjects (143 +/- 99, 422 +/- 296, 64 +/- 34, 16 +/- 10, 2550 +/- 950 pg/ml); however, the mean level of IL-4 in the patients seemed to be higher. The correlations between different cytokine levels suggested that they were produced differently. Lymphocyte counts were significantly lower in patients, but there was no difference in the other usual immunological parameters. CONCLUSIONS: Patients with advanced cancer are deficient in monocytes and the type 1 immune response. The measurement of various cytokines reported in this study provides a more sensitive and valuable tool for evaluating the function of cell-mediated immunity in cancer patients than do the usual tests.

Adult↗
PubMed1999

Specificity of omega-conotoxin MVIIC-binding and -blocking calcium channel antibodies in Lambert-Eaton myasthenic syndrome.

An immunoprecipitation assay was used to measure omega-conotoxin MVIIC (P/Q-type) binding and blocking calcium channel antibodies in 67 patients with Lambert-Eaton myasthenic syndrome (LEMS) and in a large control population. We first showed the presence of omega-conotoxin MVIIC-blocking antibody in LEMS patients. Binding antibodies were detected in 55 of 67 (82.1%) LEMS patients and in 2 of 296 (0.7%) controls. In contrast, blocking antibodies were positive in 14 of 67 (20.9%) LEMS patients and 8 of 171 (4.7%) controls. No LEMS patient had negative binding antibodies and positive blocking antibodies. The immunoprecipitation assay detected no antibodies against the whole P/Q-type calcium channel in either the paraneoplastic cerebellar degeneration or the amyotrophic lateral sclerosis sera. Neither the omega-conotoxin MVIIC-binding nor the -blocking calcium channel antibodies were correlated with clinical severity across the individuals, but longitudinal studies of some LEMS patients showed an inverse relation between binding antibody titre and disease severity. We concluded that the 125I-omega-conotoxin MVIIC assay for anti-P/Q-type voltage-gated calcium channel antibodies is highly specific for LEMS and that this sensitive binding antibody assay could be more valuable than the blocking antibody assay in the diagnosis of LEMS.

Antibodies↗