Search PubMed⌕ Search

Biomedical subjects

Hideyuki Kobayashi

Publications and source records attributed to Hideyuki Kobayashi.

At least 37 records · Page 2Linked to original sources
PubMed2004

Structure and function of a family 10 beta-xylanase chimera of Streptomyces olivaceoviridis E-86 FXYN and Cellulomonas fimi Cex.

The catalytic domain of xylanases belonging to glycoside hydrolase family 10 (GH10) can be divided into 22 modules (M1 to M22; Sato, Y., Niimura, Y., Yura, K., and Go, M. (1999) Gene (Amst.) 238, 93-101). Inspection of the crystal structure of a GH10 xylanase from Streptomyces olivaceoviridis E-86 (SoXyn10A) revealed that the catalytic domain of GH10 xylanases can be dissected into two parts, an N-terminal larger region and C-terminal smaller region, by the substrate binding cleft, corresponding to the module border between M14 and M15. It has been suggested that the topology of the substrate binding clefts of GH10 xylanases are not conserved (Charnock, S. J., Spurway, T. D., Xie, H., Beylot, M. H., Virden, R., Warren, R. A. J., Hazlewood, G. P., and Gilbert, H. J. (1998) J. Biol. Chem. 273, 32187-32199). To facilitate a greater understanding of the structure-function relationship of the substrate binding cleft of GH10 xylanases, a chimeric xylanase between SoXyn10A and Xyn10A from Cellulomonas fimi (CfXyn10A) was constructed, and the topology of the hybrid substrate binding cleft established. At the three-dimensional level, SoXyn10A and CfXyn10A appear to possess 5 subsites, with the amino acid residues comprising subsites -3 to +1 being well conserved, although the +2 subsites are quite different. Biochemical analyses of the chimeric enzyme along with SoXyn10A and CfXyn10A indicated that differences in the structure of subsite +2 influence bond cleavage frequencies and the catalytic efficiency of xylooligosaccharide hydrolysis. The hybrid enzyme constructed in this study displays fascinating biochemistry, with an interesting combination of properties from the parent enzymes, resulting in a low production of xylose.

Catalytic Domain↗
PubMed2004

Osteopontin as a positive regulator in the osteoclastogenesis of arthritis.

We examined the role of osteopontin (OPN) in the osteoclastogenesis of arthritis using collagen-induced arthritis (CIA). Cells from arthritic joints of wild-type (OPN +/+) mice spontaneously developed bone-resorbing osteoclast-like cells (OCLs). The cultured cells showed an enhanced expression of receptor activator of nuclear factor kappaB ligand (RANKL) and a decreased expression of osteoprotegerin (OPG). The addition of OPG reduced the number of OCLs, indicating that the osteoclastogenesis depends on the RANK/RANKL/OPG system. The cells also produced OPN abundantly and anti-OPN neutralizing antibodies suppressed the development of OCLs. Moreover, the addition of OPN increased the expression of RANKL and augmented differentiation of OCLs from OPN-deficient (OPN -/-) cells. OPN, like the combination of 1alpha,25-dihydroxyvitamin D(3) and dexamethasone, also enhanced the RANKL expression and decreased OPG expression in a stromal cell line, ST2. These results suggest that OPN acts as a positive regulator in the osteoclastogenesis of arthritis through the RANK/RANKL/OPG system.

Animals↗
PubMed2004

Molecular cloning and expression in Escherichia coli of a Trichoderma viride endo-beta-(1-->6)-galactanase gene.

The nucleotide sequence depicted in Figure 1 has been submitted to the DDBJ nucleotide sequence database under the accession no. AB104898. A gene encoding endo-beta-(1-->6)-galactanase from Trichoderma viride was cloned by reverse transcriptase-PCR and expressed in Escherichia coli. The gene contained an open reading frame consisting of 1437 bp (479 amino acids). The deduced amino acid sequence of the protein showed little similarity with other known glycoside hydrolases. A signal sequence (20 amino acids) was found at the N-terminal region of the protein and the molecular mass of the mature form was calculated to be 50.488 kDa. The gene product expressed in E. coli as a recombinant protein fused with thioredoxin and His(6) tags had almost the same substrate specificity and mode of action as native enzyme purified from a commercial cellulase preparation of T. viride, i.e. recombinant enzyme endo-hydrolysed beta-(1-->6)-galacto-oligomers with a DP (degree of polymerization) higher than 3, and it could also hydrolyse alpha-L-arabinofuranosidase-treated arabinogalactan protein from radish. It produced beta-(1-->6)-galacto-oligomers ranging from DP 2 to at least 8 at the initial hydrolysis stage and galactose and beta-(1-->6)-galactobiose as the major products at the final reaction stage. These results indicate that the cloned gene encodes an endo-beta-(1-->6)-galactanase. As far as we know, this is the first time an endo-beta-(1-->6)-galactanase has been cloned.

Amino Acid Sequence↗
PubMed2004

Granular cell tumor of the breast preoperatively diagnosed by fine-needle aspiration cytology: report of a case.

Granular cell tumors (GCTs) have a characteristic cytological appearance, and fine-needle aspiration cytology (FNAC) has been suggested to be the diagnostic modality of choice. However, the differential diagnosis has not yet been well described. We herein describe a rare case of GCT of the breast and discuss the differential diagnosis. A 53-year-old woman presented to our hospital with a left breast mass. In clinical and radiological examinations, the mass was suspected to be malignant. Cytologically, the tumor was composed of cohesive groups of cells with a syncytial appearance, and the cells contained abundant, finely eosinophilic cytoplasmic granules and small round-to-slightly-oval nuclei, thus suggesting the presence of benign GCT. The results of immunohistochemical staining supported the proposed deviation from Schwann cells. This case emphasizes the fact that GCTs are a rare but important possibility in the differential diagnosis of breast tumors, and that FNAC may provide clinically useful information on the management of such lesions.

Biopsy, Needle↗
PubMed2004

Theoretical study about remarkable stability of guanine tetramer.

The cyclic guanine tetramer (G-quartet) formation was theoretically studied. Total hydrogen bond energy in a G-quartet was large (-70.89 kcal/mol). though the hydrogen bond energy in Hoogsteen type guanine dimer was small (-11.26 kcal/mol). A large attractive interaction (-57.84 kcal/mol) was observed for stacking interaction. The hydration effect should be considered to explain the selectivity of metal incorporation into the G-quartet.

Guanine↗
PubMed2004

Site-directed incorporation of non-natural amino acid into Streptomyces xylanase.

A key residue, W26G existing around the substrate-binding cleft of beta-1,4-xylanase from Streptomyces olivaceoviridis E-86 (SoXyn10A), was ascertained in this study. Several kinds of W266 mutants substituted by Trp analogs were synthesized by a site-directed incorporation method to elucidate the functional role of this aromatic residue. Significant decreases of hydrolytic activities were observed in all mutants, even though the substitution of the aromatic side chain was not so drastic, suggesting that the W266 residue had a fatal role in the hydrolytic activity of SoXyn10A.

Amino Acids↗
PubMed2004

Molecular mechanisms and drug development in aquaporin water channel diseases: aquaporins in the brain.

Water homeostasis of the brain is essential for its neuronal activity. Changes in water content in the intra- and extra-cellular space affect ionic concentrations and therefore modify neuronal activity. Aquaporin (AQP) water channels may have a central role in keeping water homeostasis in the brain. Among AQP subtypes cloned in mammalian, only AQP1, AQP4, and AQP9 were identified in the brain. Changes in AQP expression may be correlated with edema formation of the brain. In this review, we describe the physiological function of AQPs and the regulatory mechanism of their expression in the brain.

Animals↗
PubMed2004

[Influence of serum homocysteine level on coronary atherosclerosis in Japanese].

OBJECTIVES: This study investigated the relationship between serum homocysteine level and coronary artery disease in Japanese. METHODS: Serum homocysteine level was measured in 200 consecutive patients who underwent coronary angiography for the assessment of ischemic heart disease. Patients with acute myocardial infarction were excluded, so 197 patients were included in this study. The patients were classified into four groups based on number of diseased vessels identified by coronary angiography: no significant stenosis group (non-vessel group), one-vessel group, two-vessel group, and three-vessel group. More than 50% stenosis was defined as diseased vessels. RESULTS: Serum homocysteine level in the three-vessel group (13.5 +/- 8.0 microM) was significantly higher than that in the non-vessel group (9.9 +/- 2.7 microM), one-vessel group (9.1 +/- 2.3 microM), and two-vessel group (10.4 +/- 3.3 microM). Patients were classified into quartile groups according to the serum homocysteine level. The number of diseased vessels and frequency of three-vessel disease tended to be higher with increasing serum homocysteine level. There was no significant relationship between serum homocysteine level and coronary risk factors (diabetes mellitus, hyperlipidemia, smoking habit) except hypertension. Multivariate analysis for the predictor of number of diseased vessels showed diabetes mellitus, hypertension, and serum homocysteine level were independent predictors. CONCLUSIONS: Elevation of plasma homocysteine level is related to the severity of coronary artery disease in Japanese.

Aged↗
PubMed2003

Crystal structures of decorated xylooligosaccharides bound to a family 10 xylanase from Streptomyces olivaceoviridis E-86.

The family 10 xylanase from Streptomyces olivaceoviridis E-86 (SoXyn10A) consists of a GH10 catalytic domain, which is joined by a Gly/Pro-rich linker to a family 13 carbohydrate-binding module (CBM13) that interacts with xylan. To understand how GH10 xylanases and CBM13 recognize decorated xylans, the crystal structure of SoXyn10A was determined in complex with alpha-l-arabinofuranosyl- and 4-O-methyl-alpha-d-glucuronosyl-xylooligosaccharides. The bound sugars were observed in the subsites of the catalytic cleft and also in subdomains alpha and gamma of CBM13. The data reveal that the binding mode of the oligosaccharides in the active site of the catalytic domain is entirely consistent with the substrate specificity and, in conjunction with the accompanying paper, demonstrate that the accommodation of the side chains in decorated xylans is conserved in GH10 xylanases of SoXyn10A against arabinoglucuronoxylan. CBM13 was shown to bind xylose or xylooligosaccharides reversibly by using nonsymmetric sugars as the ligands. The independent multiple sites in CBM13 may increase the probability of substrate binding.

Binding Sites↗
PubMed2003

Crystallization and preliminary X-ray crystallographic studies of alpha-galactosidase I from Mortierella vinacea.

alpha-Galactosidases catalyze the hydrolysis of a galactosyl residue from galactooligosaccharides and galactopolysaccharides. alpha-Galactosidase I from Mortierella vinacea was crystallized in two crystal forms using the hanging-drop vapour-diffusion method. Type 1 crystals belonged to space group I422, with unit-cell parameters a = b = 142.4, c = 131.5 A, and diffracted to beyond 2.1 A resolution, while type 2 crystals belonged to space group P4, with unit-cell parameters a = b = 100.9, c = 102.7 A, and diffracted to beyond 1.6 A resolution. This enzyme crystallized as a glycoprotein tetramer and the tetrameric structure was located around the crystallographic fourfold axis.

Bacterial Proteins↗
PubMed2003

Crystal structure of rice alpha-galactosidase complexed with D-galactose.

alpha-Galactosidases catalyze the hydrolysis of alpha-1,6-linked galactosyl residues from galacto-oligosaccharides and polymeric galacto-(gluco)mannans. The crystal structure of rice alpha-galactosidase has been determined at 1.5A resolution using the multiple isomorphous replacement method. The structure consisted of a catalytic domain and a C-terminal domain and was essentially the same as that of alpha-N-acetylgalactosaminidase, which is the same member of glycosyl hydrolase family 27. The catalytic domain had a (beta/alpha)8-barrel structure, and the C-terminal domain was made up of eight beta-strands containing a Greek key motif. The structure was solved as a complex with d-galactose, providing a mode of substrate binding in detail. The d-galactose molecule was found bound in the active site pocket on the C-terminal side of the central beta-barrel of the catalytic domain. The d-galactose molecule consisted of a mixture of two anomers present in a ratio equal to their natural abundance. Structural comparisons of rice alpha-galactosidase with chicken alpha-N-acetylgalactosaminidase provided further understanding of the substrate recognition mechanism in these enzymes.

Amino Acid Sequence↗
PubMed2003

Differential effects of bupivacaine enantiomers, ropivacaine and lidocaine on up-regulation of cell surface voltage-dependent sodium channels in adrenal chromaffin cells.

In cultured bovine adrenal chromaffin cells, (+/-)-bupivacaine inhibited veratridine-induced 22Na(+) influx (IC(50) 6.8 microM). The IC(50) of (+)-bupivacaine (2.8 microM) was 6.2-, 7.4-, and 17.1-fold lower than those of (-)-bupivacaine (17.3 microM), (-)-ropivacaine (20.6 microM), and lidocaine (47.8 microM). Chronic (i.e. 3-h) treatment of cells with (+/-)-bupivacaine increased cell surface [3H]saxitoxin ([3H]STX) binding capacity by 48% (EC(50) of 233 microM; t(1/2)=7.4 h), without changing the K(d) value. Treatment for 24 h with either (+)- or (-)-bupivacaine, or (-)-ropivacaine elevated [3H]STX binding, whereas 24-h treatment with lidocaine had no effect. The rise of [3H]STX binding by (+/-)-bupivacaine was prevented by cycloheximide, an inhibitor of protein synthesis, or brefeldin A, an inhibitor of cell surface vesicular exit from the trans-Golgi network; however, (+/-)-bupivacaine did not increase Na(+) channel alpha- and beta(1)-subunit mRNA levels. In cells subjected to (+/-)-bupivacaine treatment (1 mM for 24 h) followed by 3-h washout, veratridine-induced 22Na(+) influx was enhanced, even when measured in the presence of ouabain, an inhibitor of Na(+),K(+)-ATPase. Ptychodiscus brevis toxin-3 potentiated veratridine-induced 22Na(+) influx by 2.3-fold in the (+/-)-bupivacaine-treated cells, as in non-treated cells. These results suggest that lipophilic bupivacaine enantiomers or (-)-ropivacaine acutely inhibit Na(+) channel gating, whereas its chronic treatment up-regulates cell surface expression of Na(+) channels via translational and externalization events.

Amides↗
PubMed2003

Purification and characterization of alpha-galactosidase from sunflower seeds.

From 100 g sunflower seeds, 1.2 mg purified alpha-galactosidase was obtained with an overall yield of 51%. The alpha-galactosidase acted on both terminal alpha-galactosyl residues and side-chain alpha-galactosyl residues of the galactomanno-oligosaccharides and galactomannans. The cDNA coding for sunflower alpha-galactosidase was cloned and the deduced amino acid sequence revealed that the mature enzyme consisted of 363 amino acid residues with a molecular weight of 40,263. Seven cysteine residues were found but no putative N-glycosylation sites were present in the sequence. The deduced amino acid sequences of mature enzyme and alpha-galactosidases from coffee, guar and Mortierella vinacea alpha-galactosidase II showed over 81%, 77%, and 47% homology, respectively. These enzymes are classified into the third group in which the enzyme has no insertion sequence and a broad specificity on galactomanno-oligosaccharides compared to the other groups.

Amino Acid Sequence↗
PubMed2003

A case of multicentric Castleman's disease demonstrating severe eosinophilia and enhanced production of interleukin-5.

INTRODUCTION: Castleman's disease (CD), idiopathic lymph-node hyperplasia, is a heterogeneous disease of unknown origin. Although the pathophysiology is yet to be elucidated, interleukin (IL)-6 produced by swollen lymph nodes has been reported to play a crucial role in CD. CASE REPORT: This report presents a case of a 37-yr-old man with CD showing marked elevation of IL-6, hypereosinophilia, and also IL-5 elevation. To date, IL-5 has not been reported to influence CD. However, because in this case the serum concentration of IL-5 produced from swollen lymph nodes paralleled the general symptoms, IL-5, in addition to IL-6, may have played an important role in the disease. DISCUSSION: Although in CD the serum IL-5 level is generally within the normal range, mild eosinophilia is a common complication of the disease. This case indicates that IL-5 can also influence eosinophilia. Taken together, this suggests that there may be a more general association between local production of IL-5 and the pathology of CD.

Adult↗
PubMed2003

Enhanced production of osteopontin in multiple myeloma: clinical and pathogenic implications.

In this study, we examined osteopontin (OPN) production in myeloma cells and plasma OPN levels in multiple myeloma (MM) patients. We assessed OPN production in bone marrow cells (BMCs) by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA). We also assessed OPN production in various B-cell malignant cell lines, including three myeloma cell lines by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. In addition, we measured plasma OPN concentrations by ELISA in 30 MM patients, 21 monoclonal gammopathy of undetermined significance (MGUS) patients and 30 healthy volunteers. As a result, in an immunocytochemical study, abundant OPN was detected in BMCs from overt MM patients, whereas no OPN was detected in BMCs from patients with other haematological diseases, including MGUS. Cultured BMCs from overt MM patients produced more OPN than those from patients with either smouldering MM or MGUS. Myeloma cell lines spontaneously produced OPN. Plasma OPN levels of MM patients were significantly higher than those of MGUS patients and healthy volunteers (P < 0.05). Moreover, they correlated with both progression and bone destruction of the disease (P < 0.05). These suggest that myeloma cells actively produce OPN, which possibly contributes to osteoclastic bone resorption in MM. Plasma OPN levels may be a useful biomarker for assessing bone destruction in MM and distinguishing MM from MGUS or smouldering MM.

Biomarkers, Tumor↗
PubMed2003

Distinct effects of ketone bodies on down-regulation of cell surface insulin receptor and insulin receptor substrate-1 phosphorylation in adrenal chromaffin cells.

Treatment (>/=24 h) of cultured bovine adrenal chromaffin cells with ketoacidosis-related concentrations (>/=3 mM) of acetoacetate (but not beta-hydroxybutyrate, acetone, and acidic medium) caused a time- and concentration-dependent reduction of cell surface (125)I-insulin binding by ~38%, with no change in the K(d) value. The reduction of (125)I-insulin binding returned to control nontreated level at 24 h after the washout of acetoacetate-treated cells. Acetoacetate did not increase the internalization rate of cell surface insulin receptor (IR), as measured in the presence of brefeldin A, an inhibitor of cell surface vesicular exit from the trans-Golgi network. Acetoacetate (10 mM for 24 h) lowered cellular levels of the immunoreactive IR precursor molecule (approximately 190 kDa) and IR by 22 and 28%, respectively. Acetoacetate decreased IR mRNA levels by approximately 23% as early as 6 h, producing their maximum plateau reduction at 12 and 24 h. The half-life of IR mRNA was shortened by acetoacetate from 13.6 to 9.5 h. Immunoprecipitation followed by immunoblot analysis revealed that insulin-induced (100 nM for 10 min) tyrosine-phosphorylation of insulin receptor substrate-1 (IRS-1) was attenuated by 56% in acetoacetate-treated cells, with no change in IRS-1 level. These results suggest that chronic treatment with acetoacetate selectively down-regulated the density of cell surface functional IR via lowering IR mRNA levels and IR synthesis, thereby retarding insulin-induced activation of IRS-1.

3-Hydroxybutyric Acid↗
PubMed2003

Destabilization of Na(v)1.7 sodium channel alpha-subunit mRNA by constitutive phosphorylation of extracellular signal-regulated kinase: negative regulation of steady-state level of cell surface functional sodium channels in adrenal chromaffin cells.

In cultured bovine adrenal chromaffin cells expressing Na(v)1.7 isoform of voltage-dependent Na(+) channels, treatment (> or = 6 h) with serum deprivation, PD98059, or U0126 increased cell surface [(3)H]saxitoxin ([(3)H]STX) binding by approximately 58% (t(1/2) = 12.5 h), with no change in the K(d) value. Immunoblot analysis showed that either treatment attenuated constitutive phosphorylation of extracellular signal-regulated kinase (ERK) 1 and ERK2 but not of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK) 1 and JNK2. The increase of [(3)H]STX binding and the attenuated phosphorylation of ERK1 and ERK2 returned to the control nontreated levels after the addition of serum or the washout of PD98059- or U0126-treated cells. Simultaneous treatment of serum deprivation with PD98059 or U0126 did not produce an additional increasing effect on [(3)H]STX binding, compared with either treatment alone. In cells subjected to either treatment, veratridine-induced maximum (22)Na(+) influx was augmented by approximately 47%, with no change in the EC(50) value; Ptychodiscus brevis toxin-3 enhanced veratridine-induced (22)Na(+) influx by 2-fold, as in nontreated cells. Serum deprivation, PD98059, or U0126 increased Na(+) channel alpha- but not beta(1)- subunit mRNA level by approximately 50% between 3 and 24 h; cycloheximide, an inhibitor of protein synthesis, increased alpha-subunit mRNA level and nullified additional increasing effect of either treatment on alpha-subunit mRNA level. Either treatment prolonged half-life of alpha-subunit mRNA from 17.5 to approximately 26.3 h without altering alpha-subunit gene transcription. Thus, constitutively phosphorylated/activated ERK destabilizes Na(+) channel alpha-subunit mRNA via translational event, which negatively regulates steady-state level of alpha-subunit mRNA and cell surface expression of functional Na(+) channels.

Adrenal Glands↗