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S Fukumoto

Publications and source records attributed to S Fukumoto.

At least 19 recordsLinked to original sources
PubMed2003

Cadherin-related neuronal receptors in incisor development.

Cadherins are cell adhesion molecules that are critical for tissue development. In this report, we identified members of the cadherin family cadherin-related neuronal receptors (CNRs) 1 and 5 expressed in rat incisors by the differential display method. Quantitative RT-PCR revealed that CNR1 mRNA is expressed in the secretory stage but reduced in the early-maturation stage, while CNR5 mRNA is expressed in both these stages. In situ hybridization showed that strong expression of CNR1 is strong in the secretory stage, but reduced in the early phase and diminished in the late phase of the early-maturation stage. CNR5 mRNA is expressed almost at the same levels in the secretory and in the early phase of the early-maturation stages but is absent in the late phase of the early-maturation stage. Both CNR1 and 5 mRNA are continuously expressed in odontoblasts. Immunohistology showed that CNR proteins are expressed in the secretory and early-maturation stages of ameloblasts, but no protein expression at the late-maturation stage was observed. CNR proteins were continuously expressed in odontoblasts. We found that recombinant CNR1 binds dental epithelial and mesenchymal cells through N-terminal domain EC1 in vitro. These results suggest that CNR1 and CNR5 may play an important role in enamel and dentin formation, probably through cell-cell and/or cell-matrix interactions.

Ameloblasts↗
PubMed2002

Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats.

Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats.

Animals↗
PubMed2001

Serodiagnosis of Toxoplasma gondii infection in cats by enzyme-linked immunosorbent assay using recombinant SAG1.

The gene encoding surface antigen 1 (SAG1, P30) of Toxoplasma gondii (T. gondii) was cloned into the plasmid pGEX-4T-3 and subsequently expressed in Escherichia coli (E. coli) as a glutathione-S-transferase (GST) fusion protein. The recombinant SAG1 (rSAG1) was refolded using 8M urea solution followed by dialysis and thereafter evaluated in an enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of toxoplasmosis. The test sera were adsorbed with GST to block non-specific reactivity to the GST-SAG1 fusion protein. The ELISA with rSAG1 was able to differentiate very clearly between sera from cats or mice experimentally infected with T. gondii and sera from normal cats or mice. The ELISA detected no cross-reactivity with sera from mice experimentally infected with the closely related parasite Neospora caninum (N. caninum). Some 193 cat sera were tested for antibodies to T. gondii, out of which 40 (20.7%) reacted positively by ELISA with the rSAG1 while another 79.3% cats reacted negative to the assay. Both positive and negative sera were confirmed by Western blot analysis. The results of ELISA were in agreement with those of a commercially available latex agglutination test (LAT) kit, although the former had higher titers than the latter.

Animals↗
PubMed2001

Lactosylceramide is essential for the osteoclastogenesis mediated by macrophage-colony-stimulating factor and receptor activator of nuclear factor-kappa B ligand.

Glycosphingolipids and their metabolites play important roles in a variety of biological processes. Several signal molecules are localized in a glycolipid-enriched microdomain on the cell surface, and their signals are regulated by the glycolipid composition. However, the function of glycolipids in osteoclastogenesis has not been clearly understood. We found that D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), a glucosylceramide synthase inhibitor, completely inhibits the osteoclast formation induced by macrophage-colony-stimulating factor and receptor activator of nuclear factor-kappa B ligand (RANKL) in a dose-dependent manner. Expression of RANK, the receptor of RANKL, induced by macrophage colony-stimulating factor, was reduced markedly in D-PDMP-treated cells. d-PDMP also inhibited the phosphorylation of the inhibitor of nuclear factor-kappa B and extracellular signal-regulated kinase 1/2 induced by RANKL. In several experiments with the addition of glycolipids to D-PDMP-treated purified bone marrow cells, lactosylceramide (LacCer) strongly affected the differentiation into tartrate-resistant acid phosphatase mononucleated cells, but not positive multinucleated cells. GM3 and GM1 also recovered, but less effectively compared with LacCer. Moreover, exogenous LacCer recovered the reduced expression of RANK and the phosphorylation of inhibitor of NF-kappa B and extracellular signal-regulated kinase 1/2 after stimulation by RANKL at the same level of cells without D-PDMP treatment. Our data suggest that glycosphingolipids, especially LacCer, are necessary for the initiation step of RANKL-induced osteoclastogenesis.

Animals↗
PubMed2001

Potent and selective inhibition of the human Na+/H+ exchanger isoform NHE1 by a novel aminoguanidine derivative T-162559.

We isolated Na+/H+ exchanger (NHE)-deficient Chinese hamster ovary (CHO-K1) cells stably expressing human NHE isoforms (hNHE1, hNHE2 and hNHE3) and established an assay system for measuring their Na+/H+ exchange activity by monitoring intracellular pH alterations. Using this assay system, we demonstrated that the acylguanidine derivatives, cariporide and eniporide, cause selective inhibition of hNHE1 (IC50 value of 30 nM for cariporide, IC50 value of 4.5 nM for eniporide). Furthermore, we found that a novel synthetic aminoguanidine derivative, T-162559 ((5E,7S)-[7-(5-fluoro-2-methylphenyl)-4-methyl-7,8-dihydro-5(6H)-quinolinylideneamino] guanidine dimethanesulfonate), causes a selective inhibition of hNHE1 with more potent activity than cariporide and eniporide (IC50 value of 0.96 nM). This compound did not affect Na+/HCO3- cotransport and Na+/Ca2+ exchange.

Animals↗
PubMed2001

Ganglioside G(D2) in small cell lung cancer cell lines: enhancement of cell proliferation and mediation of apoptosis.

Expression levels of gangliosides and glycosyltransferase genes responsible for their syntheses in human lung cancer cell lines and a normal bronchial epithelial cell line were analyzed. Both non-small cell lung cancers and small cell lung cancers (SCLCs) mainly expressed G(M2) and G(M1), whereas only SCLCs expressed b-series gangliosides, such as G(D2), G(D1b), and G(T1b). Accordingly, many SCLC cell lines showed up-regulation of the G(D3) synthase gene. Consequently, we introduced G(D3) synthase cDNA into a SCLC line with low expression of b-series gangliosides and analyzed the effects of newly expressed gangliosides on tumor phenotypes. The transfectant cells expressing high levels of G(D2) and G(D3) exhibited markedly increased growth rates and strongly enhanced invasion activities. Addition of anti-G(D2) monoclonal antibodies into the culture medium of these cells resulted in the marked growth suppression of G(D2)-expressing cell lines with reduced activation levels of mitogen-activated protein kinases but not of nonexpressants, suggesting that G(D2) plays important roles in cell proliferation. Moreover, G(D2)-expressing cells treated with anti-G(D2) antibodies showed features of apoptotic cell death at 30 min after addition of antibodies, i.e., shrinkage of cytoplasm, binding of Annexin V, and staining with propidium iodide, followed by DNA fragmentation. This G(D2)-mediated apoptosis was associated with caspase-3 activation and partly inhibited by a caspase inhibitor, z-Val-Ala-Asp-fluoromethyl ketone. The finding that anti-G(D2) antibodies suppressed the cell growth and induced apoptosis of SCLC cells strongly suggested the usefulness of G(D2) as a target for the therapy of disastrous cancer, although the precise mechanisms for apoptosis remain to be clarified.

Antibodies, Monoclonal↗
PubMed2001

Cloning and characterization of FGF23 as a causative factor of tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) is one of the paraneoplastic diseases characterized by hypophosphatemia caused by renal phosphate wasting. Because removal of responsible tumors normalizes phosphate metabolism, an unidentified humoral phosphaturic factor is believed to be responsible for this syndrome. To identify the causative factor of TIO, we obtained cDNA clones that were abundantly expressed only in a tumor causing TIO and constructed tumor-specific cDNA contigs. Based on the sequence of one major contig, we cloned 2,270-bp cDNA, which turned out to encode fibroblast growth factor 23 (FGF23). Administration of recombinant FGF23 decreased serum phosphate in mice within 12 h. When Chinese hamster ovary cells stably expressing FGF23 were s.c. implanted into nude mice, hypophosphatemia with increased renal phosphate clearance was observed. In addition, a high level of serum alkaline phosphatase, low 1,25-dihydroxyvitamin D, deformity of bone, and impairment of body weight gain became evident. Histological examination showed marked increase of osteoid and widening of growth plate. Thus, continuous production of FGF23 reproduced clinical, biochemical, and histological features of TIO in vivo. Analyses for recombinant FGF23 products produced by Chinese hamster ovary cells indicated proteolytic cleavage of FGF23 at the RXXR motif. Recent genetic study indicates that missense mutations in this RXXR motif of FGF23 are responsible for autosomal dominant hypophosphatemic rickets, another hypophosphatemic disease with similar features to TIO. We conclude that overproduction of FGF23 causes TIO, whereas mutations in the FGF23 gene result in autosomal dominant hypophosphatemic rickets possibly by preventing proteolytic cleavage and enhancing biological activity of FGF23.

Alanine↗
PubMed2001

Kainic acid-induced dorsal and ventral hippocampal seizures in rats.

Despite reports of differing regional seizure susceptibility in the hippocampus, hippocampal initiation of limbic seizures has not been precisely localized. We compared seizures induced by kainic acid microinjection into the left dorsal and ventral hippocampus of rats. Discharges following ventral injections rapidly propagated to the left amygdala and sensorimotor cortex unlike seizures following dorsal injections. The ventral group showed various ictal behaviors including motor manifestations, while dorsally injected rats showed only immobilization.

Amygdala↗
PubMed2001

Akt participation in the Wnt signaling pathway through Dishevelled.

Inactivation of glycogen synthase kinase 3beta (GSK3beta) and the resulting stabilization of free beta-catenin are critical steps in the activation of Wnt target genes. While Akt regulates GSK3alpha/beta in the phosphatidylinositide 3-OH kinase signaling pathway, its role in Wnt signaling is unknown. Here we report that expression of Wnt or Dishevelled (Dvl) increased Akt activity. Activated Akt bound to the Axin-GSK3beta complex in the presence of Dvl, phosphorylated GSK3beta and increased free beta-catenin levels. Furthermore, in Wnt-overexpressing PC12 cells, dominant-negative Akt decreased free beta-catenin and derepressed nerve growth factor-induced differentiation. Therefore, Akt acts in association with Dvl as an important regulator of the Wnt signaling pathway.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Novel functions of complex carbohydrates elucidated by the mutant mice of glycosyltransferase genes.

Complex carbohydrates consist of carbohydrate moieties and protein or lipid portions, resulting in the formation of glycoproteins, proteoglycans or glycosphingolipids. The polymorphic carbohydrate structures are believed to contain profound biological implications which are important in cell-cell or cell-extracellular matrix interactions. A number of studies to delineate the roles of carbohydrates have been performed, and demonstrated definite changes in their profiles, cellular phenotypic changes or, sometimes, morphological and functional changes in tissues after modification of their structures. Recent successes in the isolation of glycosyltransferase genes and their modification enzyme genes has enabled clearer demonstrations of the roles of complex carbohydrates. In particular, genetic modification of glycosyltransferase genes in mice can elucidate the biological significances of their products in vivo. Here, we summarize recent advances in the understanding of the roles of complex carbohydrates provided from studies of gene knock-out mice of glycosyltransferase and modification enzyme genes focusing on novel functions which had not been expected.

Animals↗
PubMed2001

Molecular pathways of cyclic nucleotide-induced inhibition of arterial smooth muscle cell proliferation.

Cyclic adenosine 3',5'-monophosphate (cAMP) and cyclic guanosine 3',5'-monophosphate (cGMP) are second messengers involved in the intracellular signal transduction of a wide variety of extracellular stimuli. These signals regulate many biological processes including cell proliferation, differentiation, migration, and apoptosis. Recently, significant progress has been achieved in the molecular basis underlying cyclic nucleotide regulation of cell proliferation. This review summarizes our knowledge of the signaling pathways regulated by cyclic nucleotides in arterial smooth muscle cells.

Animals↗
PubMed2001

Parathyroid hormone increases the expression level of matrix metalloproteinase-13 in vivo.

Parathyroid hormone (PTH) increases serum calcium (Ca) by enhancing bone resorption and renal Ca reabsorption. However, detailed mechanisms of enhanced bone resorption by PTH remain to be elucidated. Although PTH has been shown to increase the expression level of osteoblastic matrix metalloproteinase (MMP)-13 in vitro, only limited results are available regarding the in vivo regulation of MMP expression. In the present study, we have examined expression levels of MMPs in PTH-infused rats. Infusion of 1.5 or 2.0 nmol/kg/day rat PTH(1-34) for 3 days resulted in a dose-dependent increase in serum Ca. PTH infusion also decreased serum phosphate levels and increased urinary excretion of Ca and phosphate. Infusion of PTH for 7 days resulted in less severe hypercalcemia and hypophosphatemia. Urinary Ca and phosphate excretion in rats infused for 7 days was less than that in rats infused for 3 days. Northern blot analysis showed that PTH infusion increased the expression level of MMP-13 in calvaria, although it did not affect MMP-2 expression. Furthermore, the time-course and severity of hypercalcemia and hypercalciuria correlated with the expression level of MMP-13. In situ hybridization also showed that PTH infusion increased the expression level of MMP-13 in femora. These results indicate that PTH enhances MMP-13 expression in vivo and suggest that PTH stimulates bone resorption at least partly by enhancing MMP-13 expression.

Animals↗
PubMed2001

Excretory/secretory products from plerocercoids of Spirometra erinaceieuropaei suppress gene expressions and production of tumor necrosis factor-alpha in murine macrophages stimulated with lipopolysaccharide or lipoteichoic acid.

We previously reported that the ES products from the plerocercoids of Spirometra erinaceieuropaei reduce nitric oxide synthase and chemokine gene expression in macrophages. In this study, we show that ES products suppressed tumor necrosis factor-alpha mRNA expression and tumor necrosis factor-alpha production in murine peritoneal macrophages stimulated with lipopolysaccharide or lipoteichoic acid in vitro. When macrophages from ES product-injected mice were stimulated with lipopolysaccharide in vitro, these cells produced smaller amounts of tumor necrosis factor-alpha compared with those taken from control mice. The suppressive effects of ES products were not restored by the treatment of indomethacin or anti-IL-10 antibody, and the ES products did not induce mRNA expression of secretory leukocyte protease inhibitor. Macrophages from C3H/HeJ mice, which have a single point mutation in the Toll-like receptor 4 gene, expressed tumor necrosis factor-alpha and IL-1alpha mRNA in the presence of lipopolysaccharide, but these expressions were less than those of macrophages from C3H/HeN. ES products significantly suppressed tumor necrosis factor-alpha gene expression and tumor necrosis factor-alpha production in macrophages from C3H/HeN and C3H/HeJ mice stimulated with lipopolysaccharide. However, ES products had no effect on IL-1 mRNA expression. Our data suggest that the plerocercoids secrete the tumor necrosis factor-alpha inhibitory products to evade the host's immune system, and that tumor necrosis factor-alpha mRNA expression might be inhibited downstream from Toll-like receptor 4 in the lipopolysaccharide signaling pathway.

Animals↗
PubMed2001

Regional accumulation of 14C-zonisamide in rat brain during kainic acid-induced limbic seizures.

BACKGROUND: Zonisamide (ZNS) is an antiepileptic drug developed in Japan. Various experimental studies have investigated the effects of ZNS. However, the mechanism of action of ZNS against limbic seizures and secondary generalization is not well-known. We studied ictal regional accumulation of ZNS in the rat brain during kainic acid (KA)-induced limbic status epilepticus. METHODS: Fourteen male Wistar rats underwent a stereotactic operation. For recording the electroencephalogram (EEG), electrodes were placed in the left amygdala (LA), left dorsal hippocampus, and over the left sensorimotor cortex. For microinjection, a stainless steel cannula was also inserted into the LA. Seven days after surgery, rats were anesthetized and a catheter was inserted into the femoral vein. The animals were immobilized and allowed to recover from anesthesia for at least two hours. In eight rats, 1.0 microL (1.0 microg) of KA was injected into the LA, and 1.0 microL of phosphate buffer solution was injected into the LA in six control rats. Sixty minutes after injection, 14C-ZNS was administered intravenously, and an autoradiographic study was done. RESULTS: During limbic status epilepticus, only seizures in the sensorimotor cortex were markedly attenuated a few minutes after 14C-ZNS administration. Additionally, high uptake of 14C-ZNS was noted ipsilaterally in the sensorimotor cortex, parietal cortex and thalamus (lateral portion). In control rats, no EEG change was seen, and distribution of 14C-ZNS was rather homogeneous. CONCLUSIONS: These results suggested that ZNS suppresses secondary generalization of limbic seizures by a direct effect on the cerebral cortex.

Animals↗
PubMed2001

Specificity of carbohydrate structures of gangliosides in the activity to regenerate the rat axotomized hypoglossal nerve.

We previously reported that a ganglioside mixture from bovine brain could prevent neuronal death and promote regeneration in rats with hypoglossal nerve resection. In the present study, we have compared the neurotrophic effects of various glycosphingolipids including lactosyl-ceramide. The findings revealed that GT1b had the activity of neuronal death prevention equivalent to a ganglioside mixture or autograft, while other glycolipids exhibited about 60% activity. However, the capability to promote the regeneration varied among glycolipids, that is, GT1b (86%), GD1b (55%), GD1a (35%), GQ1b (34%), GM1 (20%), lactosyl-ceramide (17%) in the number of horseradish peroxidase-positive neurons as an indicator of regeneration. The experiments with oligosaccharides of GT1b or GD1b and ceramide showed that the carbohydrate moiety mainly exerts neurotrophic effects. These findings suggested that fine structures of carbohydrate moiety in gangliosides are critical in the regenerative activity in this hypoglossal nerve regeneration system.

Animals↗
PubMed2001

Release of flexors and intrinsic muscles for finger spasticity in cerebral palsy.

Between April 1987 and March 1996, 32 deformed hands of 31 patients with cerebral palsy were treated with combined release of the flexor digitorum profundus, flexor digitorum superficialis, and intrinsic muscles. Of these 31 patients, 26 patients (27 hands) were followed up after treatment. Improvements were evaluated by the modified classification of Zancolli et al, the classification of House et al, the object handling score, and the activity of daily living score. Improvements of more than one level on an average were observed in the modified classification of Zancolli et al and the classification of House et al. The ability to grasp, pinch, and release increased with improvement of 2.5 points in the object handling score, and activities of daily living were enhanced with improvement of 2.4 points. The fine motor skills could be facilitated, and dexterity was restored in most patients.

Adolescent↗