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M Noda

Publications and source records attributed to M Noda.

At least 127 records · Page 7Linked to original sources
PubMed2000

Binding of avian ovomucoid to shiga-like toxin type 1 and its utilization for receptor analog affinity chromatography.

Development of a simple and efficient purification procedure for Shiga-like toxin I (Stx1) was attempted. Since it has been suggested that pigeon egg white ovomucoid carries a P1 antigenic determinant, we examined its ability to bind Stx1. The ovomucoid glycoprotein fraction (GPro) was prepared from pigeon egg white by acetone precipitation, and a portion of the GPro was treated with pronase to obtain the glycopeptide fraction (GPep). When both GPro and GPep were coupled to CNBr-activated Sepharose 4B and subjected to affinity chromatography, Stx1 specifically bound to both columns. The Stx1 eluted with a buffer containing 4.5 M MgCl2 was shown to be highly purified to homogeneity by polyacrylamide gel electrophoresis under denatured condition; only two protein bands with molecular weights of 32,000 and 8000, which correspond to the A and the B subunits of Stx1, respectively, were recognized. The purified toxin showed cytotoxicity on Vero cells with a specific activity of approximately 6 x 10(8) CD50/mg protein; almost 100% of the activity was recovered from Escherichia coli cell lysate. We propose that the utilization of avian ovmucoid for the affinity chromatography provides a potentially simple, convenient, and widely available method to purify Shiga-like toxins.

Animals↗
PubMed2000

Development of EIA systems for active-form MAP kinase.

Quantitative sandwich enzyme immunoassay (EIA) systems, that can distinguish between active-form subtypes of mitogen-activated protein kinases (p44 and p42 MAP kinase, also called ERK1 and ERK2), were developed employing subtype-specific antibodies as a solid phase and an antibody specific for the phosphorylated region of MAP kinases as the detector. Using these systems, we investigated the dynamic changes in the activity of ERK1 and ERK2 in platelet-derived growth factor (PDGF)-treated rat mesangial cells and nerve growth factor (NGF)-treated PC12. Both ERK1 and ERK2 were activated immediately after stimulation, and the activity reached a maximum at 5-10 min. The total activity of both subtypes correlated well with that obtained using the conventional method. Compared with the usual methods, these systems should have a higher specificity and be more convenient and suitable for experiments with multiple samples. Moreover, as these EIA systems can be applied not only to rat MAP kinases but also to human, mouse and rabbit MAP kinases, they are potentially very useful for a range of investigations.

Angiotensin II↗
PubMed2000

SOX9 enhances aggrecan gene promoter/enhancer activity and is up-regulated by retinoic acid in a cartilage-derived cell line, TC6.

SOX9 is a transcription factor that plays a key role in chondrogenesis. Aggrecan is one of the major structural components in cartilage; however, the molecular mechanism of aggrecan gene regulation has not yet been fully elucidated. TC6 is a clonal chondrocytic cell line derived from articular cartilage. The purpose of this study was to examine whether SOX9 modulates aggrecan gene expression and to further identify molecules that regulate Sox9 expression in TC6 cells. SOX9 overexpression in TC6 cells enhanced by approximately 3-fold the transcriptional activity of the AgCAT-8 construct containing 8-kilobase (kb) promoter/first exon/first intron fragments of the aggrecan gene. SOX9 enhancement of aggrecan promoter activity was lost when we deleted a 4.5-kb fragment from the 3'-end of the 8-kb fragment corresponding to the region including the first intron. In TC6 cells, SOX9 enhanced the transcriptional activity of a reporter construct containing the Sry/Sox consensus sequence >10-fold. SOX9 enhancement of aggrecan gene promoter activity and SOX9 transactivation through the Sry/Sox consensus sequence were not observed in osteoblastic osteosarcoma cells (ROS17/2.8), indicating the dependence on the cellular background. Northern blot analysis indicated that TC6 cells constitutively express Sox9 mRNA at relatively low levels. To examine regulation of Sox9 gene expression, we investigated the effects of calciotropic hormones and cytokines. Among these, retinoic acid (RA) specifically enhanced Sox9 mRNA expression in TC6 cells. The basal levels of Sox9 expression and its enhancement by RA were observed similarly at both permissive (33 degrees C) and nonpermissive (39 degrees C) temperatures. Furthermore, RA treatment enhanced the transcriptional activity of a reporter construct containing the Sry/Sox consensus sequence in TC6 cells. Moreover, RA treatment also enhanced the transcriptional activity of another reporter construct containing the enhancer region of the type II procollagen gene in TC6 cells. These observations indicate that SOX9 enhances aggrecan promoter activity and that its expression is up-regulated by RA in TC6 cells.

Aggrecans↗
PubMed2000

Transient over-expression of NGFI-A gene suppresses NGF-induced neurite outgrowth in PCI2 cells.

Using an inducible gene expression system (Tet-ON system), the role of NGFI-A gene during the neuronal differentiation of PCI2 cells was examined. When NGFI-A was transiently over-expressed, no obvious effects on cell proliferation or neurite outgrowth were observed. Interestingly, however, NGFI-A over-expression resulted in significant retardation in NGF-induced neurite outgrowth. Similar suppressive effects were observed also on the v-K-ras-induced neurite outgrowth. These results raise the possibility that NGFI-A protein may play some negative role in NGF signaling.

Animals↗
PubMed2000

Induction of erythroid differentiation by inhibition of Ras/ERK pathway in a friend murine leukemia cell line.

The role of Ras and MAP kinases (MAPKs) in the regulation of erythroid differentiation was studied using a cell line (SKT6) derived from Friend virus (Anemic strain)-induced murine erythroleukemia. This cell line undergoes differentiation in vitro in response to erythropoietin (EPO) or other chemical inducers such as dimethylsulfoxide (DMSO). When a constitutively active ras mutant (ras12V) was expressed in SKT6 cells, EPO-induced differentiation was inhibited. Conversely, a dominant negative ras mutant (ras17N) induced differentiation even in the absence of EPO, suggesting that the basal Ras activity is essential for the maintenance of the undifferentiated phenotype and proliferative potential in this cell line. Rapid inactivation of ERK was observed after expression of ras17N. Slow but significant inactivation of ERK was also observed during EPO-induced differentiation. Furthermore, overexpression of a constitutively active mutant of ERK-activating kinase (MAPKK) was found to suppress erythroid differentiation, while pharmacological inhibition of MAPKK induced differentiation. These findings suggest that down-regulation of Ras/ERK signaling pathway may be an essential event in EPO-induced erythroid differentiation in this system.

Androstadienes↗
PubMed2000

Pleiotrophin signals increased tyrosine phosphorylation of beta beta-catenin through inactivation of the intrinsic catalytic activity of the receptor-type protein tyrosine phosphatase beta/zeta.

Pleiotrophin (PTN) is a platelet-derived growth factor-inducible, 18-kDa heparin-binding cytokine that signals diverse phenotypes in normal and deregulated cellular growth and differentiation. To seek the mechanisms of PTN signaling, we studied the interactions of PTN with the receptor protein tyrosine phosphatase (RPTP) beta/zeta in U373-MG cells. Our results suggest that PTN is a natural ligand for RPTP beta/zeta. PTN signals through "ligand-dependent receptor inactivation" of RPTP beta/zeta and disrupts its normal roles in the regulation of steady-state tyrosine phosphorylation of downstream signaling molecules. We have found that PTN binds to and functionally inactivates the catalytic activity of RPTP beta/zeta. We also have found that an active site-containing domain of RPTP beta/zeta both binds beta-catenin and functionally reduces its levels of tyrosine phosphorylation when added to lysates of pervanidate-treated cells. In contrast, an (inactivating) active-site mutant of RPTP beta/zeta also binds beta-catenin but fails to reduce tyrosine phosphorylation of beta-catenin. Finally, in parallel to its ability to inactivate endogenous RPTP beta/zeta, PTN sharply increases tyrosine phosphorylation of beta-catenin in PTN-treated cells. The results suggest that in unstimulated cells, RPTP beta/zeta is intrinsically active and functions as an important regulator in the reciprocal control of the steady-state tyrosine phosphorylation levels of beta-catenin by tyrosine kinases and phosphatases. The results also suggest that RPTP beta/zeta is a functional receptor for PTN; PTN signals through ligand-dependent receptor inactivation of RPTP beta/zeta to increase levels of tyrosine phosphorylation of beta-catenin to initiate downstream signaling. PTN is the first natural ligand identified for any of the RPTP family; its identification provides a unique tool to pursue the novel signaling pathway activated by PTN and the relationship of PTN signaling with other pathways regulating beta-catenin.

Blotting, Western↗
PubMed2000

AMPA-kainate subtypes of glutamate receptor in rat cerebral microglia.

Microglial cells were isolated from rat cerebral cortex, and kainate (KA)-induced inward current was measured at a holding potential of -40 or -60 mV. 6-Cyano-7-nitroquinoxaline-2, 3-dione-sensitive KA-induced currents increased with increasing KA concentration. The half-activation concentration and Hill coefficient were 3.3 x 10(-4) M and 1.4, respectively. Although glutamate (Glu) and AMPA-induced currents were much smaller than that induced by KA, all KA-, Glu-, and AMPA-induced currents were greatly and consistently enhanced in the presence of cyclothiazide (CTZ). On the other hand, KA-induced currents were much less sensitive to potentiation by concanavain A, suggesting that the KA-induced response in rat microglia is predominantly mediated by AMPA-preferring receptors (subunits GluR1-GluR4). The current-voltage relationships of KA- and AMPA-CTZ-induced currents were almost linear or slightly outward rectifying. The reversal potential of KA-induced current shifted to negative potentials (from +4 to -40 mV) on switching from high Na(+) to high Ca(2+) external solution, indicating the low Ca(2+) permeability through the AMPA-KA receptor channel complexes. AMPA-KA receptor expression was studied with immunohistochemistry and reverse transcription-PCR, from which GluR2, GluR3, GluR4, and GluR5 were identified. Lower levels of mRNAs for GluR7 and KA-1-KA-2 were also indicated. Finally, activation of these receptors with KA or Glu significantly enhanced the production of tumor necrosis factor-alpha. These results suggest that primary cultured rat microglia possesses functional Glu receptor, which may mediate neuron to microglia communication in the physiological and pathological states.

Animals↗
PubMed2000

Expression of the E-cadherin/catenin (alpha-, beta-, and gamma-) complex correlates with the macroscopic appearance of early gastric cancer.

E-cadherin and its associated cytoplasmic proteins, alpha-, beta-, and gamma-catenins, play an essential role in the control of epithelial differentiation. We have previously shown that loss or down-regulation of E-cadherin/catenin correlates with poor survival in advanced gastric adenocarcinoma. The aim of this study was to assess the expression of E-cadherin and catenins in early gastric cancers (EGCs). Immunohistochemical staining for E-cadherin and alpha-, beta-, and gamma-catenins was performed on 41 paraffin-embedded gastrectomy specimens of EGC using an indirect immunoperoxidase technique. The pattern of expression and cellular localization of the E-cadherin/catenin complex in tumour cells were correlated with the macroscopic appearance of the tumour according to the Japanese Endoscopic Society classification. The tumours were classified as follows: three type I (protruding) and 38 type II (superficial), of which ten were type IIa (elevated), one was type IIb (flat), and 27 were type IIc (depressed). E-cadherin and alpha-, beta-, and gamma-catenins were expressed at the cell-cell junctions in normal mucosa. Forty out of 41 tumours showed abnormal expression (loss of membranous immunoreactivity and/or nuclear staining) of at least one component of the E-cadherin catenin complex. Loss of E-cadherin immunoreactivity was more frequently seen in type IIb (1/1, 100%) and type IIc (27/27, 100%) than in type I (1/3, 33%) and type IIa (1/10, 10%) (p<0.01). Abnormal expression of E-cadherin and alpha-catenin was more frequently seen in diffuse-type than in intestinal type tumours (p<0.05). Abnormal immunoreactivity of beta- and gamma-catenin, including nuclear localization, was observed in 34% and 7.3% of tumours, respectively, but there was no significant correlation with tumour type or endoscopic appearance. In conclusion, abnormal expression of the E-cadherin/catenin complex occurs in EGC and seems to correlate with macroscopic appearances.

Adenocarcinoma↗
PubMed2000

A cellular variant of supratentorial hemangioblastoma.

Supratentorial hemangioblastomas are rarely seen, especially in children and adolescents. We report the case of a 17-year-old male with supratentorial hemangioblastoma. Neuroimaging demonstrated a cystic lesion within the right parietal lobe. Systemic examination revealed no abnormality. The lesion was not attached to the dura and was not associated with von Hippel-Lindau disease. It was very difficult to confirm the final diagnosis of this case, in spite of extensive examination by light microscopy, immunohistochemical studies, and electron microscopy.

Adolescent↗
PubMed2000

Expression of Indian hedgehog during fracture healing in adult rat femora.

Indian hedgehog (Ihh) has recently been shown to be expressed in prehypertrophic and hypertrophic chondrocytes during embryonic development, and it has been implicated in the regulation of terminal differentiation of chondrocytes. In this paper we examined the expression of Ihh during fracture healing in an adult rat model. A transverse diaphyseal fracture was made in the right femur, and the expression of Ihh in the fracture callus was examined at 1, 2, and 3 weeks after fracture. Northern blot analysis demonstrated the expression of Ihh mRNA in these tissues. Immunohistological analysis detected hedgehog protein in prehypertrophic chondrocytes in the fracture callus at 1 week after fracture. From 2 weeks and on, positive staining was observed in hypertrophic chondrocytes as well. At 3 weeks, some of the osteoblasts close to the endochondral ossification front were also stained positive for hedgehog protein. Our data indicate that Ihh is expressed in chondrocytes and osteoblasts during the process of fracture healing in adult rat femora, suggesting that Ihh, a regulator of endochondral ossification in embryonic development, may also play a role in the regulation of bone formation during fracture repair in adult animals.

Animals↗
PubMed2000

Endoscopic mucosal resection using a partial transparent hood for lesions located tangentially to the endoscope.

BACKGROUND: Numerous methods have been developed to resect early-stage gastric and esophageal cancers, but it is difficult to resect lesions viewed tangentially with the endoscope. METHODS: We have designed and developed an original method of endoscopic mucosal resection using a partial transparent hood to treat difficult cases in which the lesions are located tangentially to the endoscope. The hood was attached on the right side of the endoscope and, after insertion into the stomach or the esophagus, was lightly pressed on the orad side of the lesion. Then the lesion was resected using grasping forceps and electrosurgical current snare. RESULTS: The average diameter of specimens was 26 +/- 8 mm in gastric lesions and 20 +/- 3 mm in esophageal lesions, both 6 mm larger than those obtained by previous methods. CONCLUSION: This device and technique were extremely useful for mucosal resection of lesions located tangentially to the endoscope.

Electrosurgery↗
PubMed2000

Roles of GABAergic inhibition and NMDA receptor subunits in the spatio-temporal integration in the cerebellar cortex of mice.

The cerebellar cortex consists of relatively small numbers of identified neuronal types, which form simple and well-defined layers. However, a direct high-resolution demonstration of spatio-temporal pattern of information transmission there has been lacking. Using an optical recording technique with a membrane-potential sensitive dye, we studied the spatio-temporal pattern of excitation propagation induced by white matter stimulation in the slice preparations. We focused on physiological roles of inhibitory synapses and N-methyl-D-aspartate (NMDA) receptors. White matter stimulation induced postsynaptic long-lasting depolarization in the granular layer and transient depolarization in the molecular layer, respectively. Inhibitory synapses modestly suppressed the amplitude of slow depolarization in the granular layer, whereas they exerted powerful lateral inhibition in the molecular layer. Using mutant mice deficient in NMDA receptor subunits NR2A and/or NR2C, we also demonstrated that the NR2A and NR2C subunits expressed in granule neurons contribute to the early and late components of slow depolarization respectively, and that both subunits cooperatively support the temporal summation of depolarization. Taking into account the anatomical organization of the cerebellar cortex, these results might suggest that the granular layer is specialized more in the temporal integration of input signals and the molecular layer in the spatial integration.

Animals↗
PubMed2000

Identification of RALDH-3, a novel retinaldehyde dehydrogenase, expressed in the ventral region of the retina.

In the developing retina, a retinoic acid (RA) gradient along the dorso-ventral axis is believed to be a prerequisite for the establishment of dorso-ventral asymmetry. This RA gradient is thought to result from the asymmetrical distribution of RA-generating aldehyde dehydrogenases along the dorso-ventral axis. Here, we identified a novel aldehyde dehydrogenase specifically expressed in the chick ventral retina, using restriction landmark cDNA scanning (RLCS). Since this molecule showed enzymatic activity to produce RA from retinaldehyde, we designated it retinaldehyde dehydrogenase 3 (RALDH-3). Structural similarity suggested that RALDH-3 is the orthologue of human aldehyde dehydrogenase 6. We also isolated RALDH-1 which is expressed in the chick dorsal retina and implicated in RA formation. Raldh-3 was preferentially expressed first in the surface ectoderm overlying the ventral portion of the prospective eye region and then in the ventral retina, earlier than Raldh-1 in chick and mouse embryos. High level expression of Raldh-3 was also observed in the nasal region. In addition, we found that Pax6 mutants are devoid of Raldh-3 expression. These results suggested that Raldh-3 is the key enzyme in the formation of an RA gradient along the dorso-ventral axis during the early eye development, and also in the development of the olfactory system.

Aldehyde Oxidoreductases↗
PubMed2000

Differential tetraethylammonium sensitivity of KCNQ1-4 potassium channels.

In Shaker-group potassium channels the presence of a tyrosine residue, just downstream of the pore signature sequence GYG, determines sensitivity to tetraethylammonium (TEA). The KCNQ family of channels has a variety of amino acid residues in the equivalent position. We studied the effect of TEA on currents generated by KCNQ homomers and heteromers expressed in CHO cells. We used wild-type KCNQ1-4 channels and heteromeric KCNQ2/3 channels incorporating either wild-type KCNQ3 subunits or a mutated KCNQ3 in which tyrosine replaced threonine at position 323 (mutant T323Y). IC50 values were (mM): KCNQ1, 5.0; KCNQ2, 0.3; KCNQ3, > 30; KCNQ4, 3.0; KCNQ2 + KCNQ3, 3.8; and KCNQ2 + KCNQ3(T323Y), 0.5. While the high TEA sensitivity of KCNQ2 may be conferred by a tyrosine residue lacking in the other channels, the intermediate TEA sensitivity of KCNQ1 and KCNQ4 implies that other residues are also important in determining TEA block of the KCNQ channels.

Amino Acid Substitution↗
PubMed2000

Enhancement of poly-adenosine diphosphate-ribosylation in human hepatocellular carcinoma.

BACKGROUND: Poly-adenosine diphosphate (ADP)-ribosylation, catalysed by poly(ADP-ribose) polymerase (PARP), is a post-translational modification of nuclear proteins and is involved in a wide range of biological processes including DNA repair, cell proliferation and malignant transformation. Alteration of this reaction in human hepatocellular carcinoma (HCC) is of interest, but has not yet been explored. The aim of this study was to evaluate poly-ADP-ribosylation and to compare the expression of PARP in HCC and adjacent non-tumour tissues. METHODS: Tumorous and adjacent non-tumorous tissues were obtained from five consecutive patients with HCC during surgery for tumour resection. Tissue homogenates were subjected to ADP-ribosylation with [32P]-nicotinamide adenine dinucleotide. The ADP-ribosylated proteins were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis, followed by autoradiography. Expression of PARP was also evaluated by western blotting. RESULTS: Several proteins were ADP-ribosylated in human HCC tissues. Notably, the radiolabelling of a 116-kDa protein was remarkably greater than that in adjacent non-tumorous tissues (86.5 +/- 35.2 arbitrary units by densitometry vs 12.2 +/- 9.9, mean +/- SD, n = 5, P < 0.02). The radiolabelling of the 116-kDa protein was decreased in the presence of PARP inhibitors in a concentration-dependent manner. Immunoblot analyses revealed that the radiolabelled protein was PARP and that its expression was significantly greater in HCC than in adjacent non-tumorous tissues (333 +/- 204% of non-tumorous tissue, P < 0.05). CONCLUSIONS: We found that poly-ADP-ribosylation and PARP expression were significantly increased in human HCC compared with those in adjacent non-tumorous tissues in surgically obtained specimens.

ADP-Ribosylation Factors↗
PubMed2000

Treatment of ununited fracture of the hook of hamate by low-intensity pulsed ultrasound: a case report.

A patient presented 4 months after sustaining a fracture of the hook of hamate. X-rays and computed tomography scanning of the carpal tunnel confirmed the presence of an ununited fracture. Low-intensity ultrasound was applied to the fracture site. After 4.5 months of exposure to ultrasound, union was confirmed by both x-rays and computed tomography scanning of the carpal tunnel. (J Hand Surg 2000; 25A:77-79.

Accidents, Traffic↗
PubMed2000

The endolymphatic sac in patients with Ménière's disease: correlation between the MRI and the surgical findings.

The endolymphatic sac (ES) is thought to have close relations to pathogenesis of endolymphatic hydrops. Here is reported a retrospective study of 41 patients (42 ears) with Meniere's disease who underwent MRI prior to endolymphatic sac surgery. Based on proton-density weighted image (PDI) and T2-weighted image (T2), the ES including an endolymphatic duct (ED) were estimated whether it was detectable or not. Fourteen ESs were detected on both images (Group A), 14 ESs were detected only on PDI (Group B), and the remaining 14 ESs were not detected on either image (Group D). The actual shape of the sac, obtained from surgical findings, was classified into three (normoplastic, atrophic, invisible). Seventeen ears showed normoplastic ESs and 14 showed atrophic ESs. ES was not detected in 11 ears during surgery, and these findings were compared with image classification. From the study data, normoplastic ESs tend to be observed on both images whereas atrophic or invisible sacs were hardly observed on T2. This classification of ES on MRI was thought to correlate with surgical findings and this correlation was statistically significant (Spearman's rank correlation coefficient. r(s) = 0.58, p < 0.01).

Adult↗