Biomedical subjects

Hideyuki Kobayashi

Publications and source records attributed to Hideyuki Kobayashi.

At least 19 recordsLinked to original sources

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

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↗

PubMed2003

Purification and characterization of extracellular beta-galactosidase secreted by supension cultured rice (Oryza sativa L.) cells.

A beta-galactosidase was purified 1300-fold by lactosyl-Sepharose 4B and Sephacryl S-200 column chromatographies from the cultured medium of a rice-cell suspension. The purified enzyme appeared as 47 kD and 40 kD polypeptides on SDS-PAGE and had a specific activity of 65.1 units/mg. Optimum activity was observed at pH 3.5 and 60 degrees C. The enzyme released galactose from galactoxyloglucan and pectic galactans.

Chromatography, Liquid↗

PubMed2003

Adrenomedullin, an autocrine mediator of blood-brain barrier function.

Since the discovery that adrenomedullin gene expression is 20- to 40-fold higher in endothelial cells than even in the adrenal medulla, this peptide has been regarded as an important secretory product of the vascular endothelium, together with nitric oxide, eicosanoids, endothelin-1, and other vasoactive metabolites. Cerebral endothelial cells secrete an exceptionally large amount of adrenomedullin, and the adrenomedullin concentration is about 50% higher in the cerebral circulation than in the peripheral vasculature. The adrenomedullin production of cerebral endothelial cells is induced by astrocyte-derived factors. Adrenomedullin causes vasodilation in the cerebral circulation, may participate in the maintenance of the resting cerebral blood flow, and may be protective against ischemic brain injury. Recent data from our laboratory indicate that adrenomedullin, as an endothelium-derived autocrine/paracrine hormone, plays an important role in the regulation of specific blood-brain barrier properties. Adrenomedullin is suggested to be one of the physiological links between astrocyte-derived factors, cyclic adenosine 3'5'-monophosphate (cAMP), and the induction and maintenance of the blood-brain barrier. Moreover, the role of adrenomedullin in the differentiation and proliferation of endothelial cells and in angiogenesis suggests a more complex function for adrenomedullin in the cerebral circulation and in the development of the blood-brain barrier.

Adrenomedullin↗

PubMed2003

Pathophysiological function of adrenomedullin and proadrenomedullin N-terminal peptides in adrenal chromaffin cells.

Adrenomedullin (AM) and peptides of the proadrenomedullin N-terminal 20 peptide (PAMP20) family are multifunctional peptides abundantly expressed in the adrenal medulla. These peptides are released by regulated exocytosis along with catecholamines upon stimulation of adrenal chromaffin cells. They are also released gradually during culture, and this release is stimulated by a 3',5'-cyclic adenosine monophosphate (cAMP)-dependent pathway. The expression and release of AM increase under hypoxia in chromaffin cells. The expression of AM in pheochromocytoma PC12 cells is reduced during neuronal differentiation with nerve growth factor. On the other hand, PAMP20 and PAMP12 suppress catecholamine release and synthesis by interfering with nicotinic cholinergic receptors. AM increases blood flow in the adrenal gland, and causes a gradual release of catecholamine, but does not modify regulated exocytosis upon the stimulation of cells. Current data indicate that the expression of these peptides is regulated by intracellular signaling pathways, and changes under various physiological and pathological conditions. AM and PAMP20 family peptides have distinct physiological functions. PAMP20 and PAMP12 are endogenous peptides that modulate chromaffin cell function in an autocrine manner, whereas AM may mainly regulate vascular cell function in a paracrine manner.

Adrenal Medulla↗

PubMed2003

Delayed onset acute renal failure associated with Amanita pseudoporphyria Hongo ingestion.

A 66-year-old man with diabetes developed acute renal failure after ingestion of Amanita pseudoporphyria Hongo. Laboratory data showed acute nonoliguric renal failure. A renal biopsy showed acute tubular necrosis with glomerular minor abnormalities. He received hemodialysis treatment for 3 weeks and his renal function normalized 2 months after admission. We discuss the differences in acute renal failure caused by possible toxins of Amanita pseudoporphyria Hongo from that caused by other poisonous mushrooms.

Acute Kidney Injury↗

PubMed2003

Plaque-stabilizing effect of pitavastatin in Watanabe heritable hyperlipidemic (WHHL) rabbits.

This study investigated the effect of pitavastatin, a 3-hydroxy-3-methylglutaryl coenzyme A ( HMG-CoA ) reductase inhibitor with strong cholesterol-lowering activity, on the composition of atherosclerotic plaque. Pitavastatin ( 0.5mg/kg ) was administered to Watanabe heritable hyperlipidemic ( WHHL ) rabbits for 16 weeks, with the result that plasma total cholesterol ( TC ), very low density lipoprotein ( VLDL )-C, intermediate density lipoprotein ( IDL )-C and low density lipoprotein ( LDL )-C decreased by 28.6, 60.0, 42.3 and 21.7%, respectively. In the aorta, pitavastatin reduced the area of the lesion by 38.6%. In the pitavastatin group, the macrophage-positive area in the aortic plaque was reduced by 39.4%, and the areas occupied by collagen and a-smooth muscle actin ( alpha-SMA )-positive area increased by 66.4 and 91.7%, respectively. In the aortic arch, pitavastatin increased the average thickness of alpha-SMA in the plaque by 96.7% and reduced the vulnerability index by 76.0%. Furthermore, pitavastatin reduced the positive areas of monocyte chemoattractant protein ( MCP )-1, matrix metalloproteinase ( MMP )-3 and MMP-9 by 39.1, 40.6 and 52.3%, respectively. These results indicated that pitavastatin had an excellent lipid-lowering effect in WHHL rabbits, suppressing the progression of atherosclerosis and stabilizing atherosclerotic plaque.

Animals↗

PubMed2003

Synergistic effect on the attenuation of collagen induced arthritis in tumor necrosis factor receptor I (TNFRI) and interleukin 6 double knockout mice.

OBJECTIVE: To evaluate any additive effect on attenuation of collagen induced arthritis (CIA) in tumor necrosis factor receptor I (TNFRI) and interleukin 6 (IL-6) double knockout (DKO) mice. METHODS: CIA was induced in wild-type (Wt), TNFRI knockout (TNFRIKO), IL-6 knockout (IL-6KO), and DKO mice. Comparative studies were performed among these different mouse genotypes observing clinical (incidence, arthritis score), histological, radiologic, and immunological aspects. RESULTS: More than 90% of the Wt, TNFRIKO, and IL-6KO mice developed definite CIA, while only 20% of the DKO mice did so. Severity of arthritis, indicated by the arthritis score, was significantly reduced in both the TNFRIKO and IL-6KO mice compared with the Wt mice. Moreover, the severity of arthritis in the DKO mice was significantly reduced compared with each single KO mouse (by arthritis scores; DKO vs TNFRIKO, IL-6KO mice, p < 0.05). In addition, histological and radiologic changes were also significantly reduced in the DKO mice compared with each single KO mouse (by histological and radiologic scores; DKO vs TNFRIKO, IL-6KO mice, p < 0.05 and p < 0.01 respectively). In immunological studies, serum anti-type II collagen (anti-CII) antibody concentrations were significantly decreased in the DKO mice compared with each single KO mouse (DKO vs TNFRIKO, IL-6KO mice, p < 0.01). CONCLUSION: Simultaneous blockade of TNFRI and IL-6 showed synergistic rather than additive effects on the attenuation of CIA. Combinations of anti-TNF-a and anti-IL-6 therapy may provide clinical benefits for treatment of rheumatoid arthritis compared with therapy against each single cytokine.

Animals↗

PubMed2002

A point mutation of Tyr-759 in interleukin 6 family cytokine receptor subunit gp130 causes autoimmune arthritis.

We generated a mouse line in which the src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2 binding site of gp130, tyrosine 759, was mutated to phenylalanine (gp130(F759/F759)). The gp130(F759/F759) mice developed rheumatoid arthritis (RA)-like joint disease. The disease was accompanied by autoantibody production and accumulated memory/activated T cells and myeloid cells. Before the disease onset, the T cells were hyperresponsive and thymic selection and peripheral clonal deletion were impaired. The inhibitory effect of IL-6 on Fas ligand expression during activation-induced cell death (AICD) was augmented in gp130(F759/F759) T cells in a manner dependent on the tyrosine residues of gp130 required for signal transducer and activator of transcription 3 activation. Finally, we showed that disease development was dependent on lymphocytes. These results provide evidence that a point mutation of a cytokine receptor has the potential to induce autoimmune disease.

Amino Acid Substitution↗

PubMed2002

Crystallization and preliminary X-ray crystallographic studies of rice alpha-galactosidase.

alpha-Galactosidases catalyze the hydrolysis of galactooligosaccharides and galactopolysaccharides to alpha-galactose residues and are widely distributed in microorganisms, plants and animals. alpha-Galactosidase from rice (Oryza sativa L. ssp. japonica) was crystallized by the hanging-drop vapour-diffusion method. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 63.1, b = 71.3, c = 85.6 A, and diffract beyond 1.9 A resolution.

Crystallization↗

PubMed2002

Effects of rapid saline infusion on orthostatic intolerance and autonomic tone after 20 days bed rest.

To test whether acute volume expansion can normalize orthostatic intolerance and autonomic tone after prolonged bed rest (BR), 23 men were subjected to 20 days BR. Left ventricular (LV) echocardiography was performed during the lower body negative pressure (LBNP) test before and after BR with and without preceding rapid infusion of saline (1,500 ml/30 min). Saline infusion restored heart rate, LV dimension, and stroke volume during LBNP, increased cardiac output (from 4.1 +/- 1 to 5.3 +/- 1 L/min), and normalized LBNP tolerance time (from 11 +/- 4 to 23 +/- 6 minutes). In 9 men, a Holter electrocardiogram was recorded on the day before BR, the fourth and twentieth days of BR, and the day after BR. The high-frequency component of heart rate variability during sleep gradually decreased and reached the lowest level on the day after BR (100%, 66 +/- 16%, 39 +/- 18%, 10 +/- 8%). Thus, restoring decreased blood volume is an effective countermeasure for orthostatic intolerance after BR. However, decreased vagal tone persisted, suggesting reset autonomic tone.

Adult↗

PubMed2002

Crystal structures of the sugar complexes of Streptomyces olivaceoviridis E-86 xylanase: sugar binding structure of the family 13 carbohydrate binding module.

The family 10 xylanase from Streptomyces olivaceoviridis E-86 contains a (beta/alpha)(8)-barrel as a catalytic domain, a family 13 carbohydrate binding module (CBM) as a xylan binding domain (XBD) and a Gly/Pro-rich linker between them. The crystal structure of this enzyme showed that XBD has three similar subdomains, as indicated by the presence of a triple-repeated sequence, forming a galactose binding lectin fold similar to that found in the ricin toxin B-chain. Comparison with the structure of ricin/lactose complex suggests three potential sugar binding sites in XBD. In order to understand how XBD binds to the xylan chain, we analyzed the sugar-complex structure by the soaking experiment method using the xylooligosaccharides and other sugars. In the catalytic cleft, bound sugars were observed in the xylobiose and xylotriose complex structures. In the XBD, bound sugars were identified in subdomains alpha and gamma in all of the complexes with xylose, xylobiose, xylotriose, glucose, galactose and lactose. XBD binds xylose or xylooligosaccharides at the same sugar binding sites as in the case of the ricin/lactose complex but its binding manner for xylose and xylooligosaccharides is different from the galactose binding mode in ricin, even though XBD binds galactose in the same manner as in the ricin/galactose complex. These different binding modes are utilized efficiently and differently to bind the long substrate to xylanase and ricin-type lectin. XBD can bind any xylose in the xylan backbone, whereas ricin-type lectin recognizes the terminal galactose to sandwich the large sugar chain, even though the two domains have the same family 13 CBM structure. Family 13 CBM has rather loose and broad sugar specificities and is used by some kinds of proteins to bind their target sugars. In such enzyme, XBD binds xylan, and the catalytic domain may assume a flexible position with respect to the XBD/xylan complex, inasmuch as the linker region is unstructured.

Binding Sites↗

PubMed2002

Expression of osteopontin at sites of bone erosion in a murine experimental arthritis model of collagen-induced arthritis: possible involvement of osteopontin in bone destruction in arthritis.

OBJECTIVE: To investigate the involvement of osteopontin (OPN) in bone destruction in a murine experimental arthritis model of collagen-induced arthritis (CIA). METHODS: The expression of OPN was examined at both the messenger RNA (mRNA) and protein levels in various arthritic lesions in mice with CIA by in situ hybridization and immunohistochemistry, respectively. In addition, the expression of alpha(v)beta3 integrin, a receptor for OPN, the ligation of which is thought to be essential for bone resorption by osteoclasts, was examined by immunohistochemistry. Plasma concentrations of OPN were measured at different time points in the course of CIA by enzyme-linked immunosorbent assay. RESULTS: OPN mRNA was detected mainly at sites of bone erosion in arthritic lesions, where activated osteoclasts were present; OPN protein was also detected at sites of bone erosion. In the arthritic synovium, OPN was predominantly expressed in the synovial lining layer, but not in lymphoid aggregates. In addition, alpha(v)beta3 integrin was detected coincident with OPN at sites of bone erosion (bone-pannus junction). Plasma OPN levels were markedly elevated at the time points that corresponded to arthritis flares, and higher levels were maintained during the progression of arthritis. CONCLUSION: OPN may mediate bone resorption by osteoclasts in arthritis through ligation with its receptor, alpha(v)beta3 integrin. OPN may be a useful therapeutic target molecule in the prevention of bone destruction in arthritis.

Animals↗

PubMed2002

alpha-Galactosidase from cultured rice (Oryza sativa L. var. Nipponbare) cells.

The alpha-galactosidase from rice cell suspension cultures was purified to homogeneity by different techniques including affinity chromatography using N-epsilon-aminocaproyl-alpha-D-galactopyranosylamine as the ligand. From 11 l of culture filtrate, 28.7 mg of purified enzyme was obtained with an overall yield of 51.9%. The cDNA coding for the alpha-galactosidase was cloned and sequenced. The enzyme was found to contain 417 amino acid residues composed of a 55 amino acid signal sequence and 362 amino acid mature alpha-galactosidase; the molecular weight of the mature enzyme was thus calculated to be 39,950. Seven cysteine residues were also found but no putative N-glycosylation sites were present. The observed homology between the deduced amino acid sequences of the mature enzyme and alpha-galactosidases from coffee (Coffea arabica), guar (Cyamopsis tetragonolooba), and Mortierella vinacea alpha-galactosidase II were over 73, 72, and 45%, respectively. The enzyme displayed maximum activity at 45 degrees C when p-nitrophenyl-alpha-D-galactopyranoside was used as substrate. The rice alpha-galactosidase and Mortierella vinacea alpha-galactosidase II acted on both the terminal alpha-galactosyl residue and the side-chain alpha-galactosyl residue of the galactomanno-oligosaccharides.

Amino Acid Sequence↗