Biomedical subjects

Hideyuki Kobayashi

Publications and source records attributed to Hideyuki Kobayashi.

At least 55 records · Page 3Linked to original sources

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↗

PubMed2002

Infiltrating eosinophils and eotaxin: their association with idiopathic eosinophilic esophagitis.

BACKGROUND: Idiopathic eosinophilic esophagitis (IEE) is a very rare disease characterized by thickening and eosinophil infiltration of the esophagus. The most potent chemotactic factor for eosinophils is eotaxin, and its pathophysiologic significance in IEE needs to be elucidated. OBJECTIVE: To study the association between eotaxin and IEE. METHODS: We examined eotaxin expression in the esophagus of an IEE patient in comparison to controls by immunohistochemistry using a monoclonal antibody for human eotaxin. We also measured the free eotaxin level and the total (free and bound-form) eotaxin level in blood by enzyme-linked immunosorbent assay before and after the initiation of steroid therapy. RESULTS: Most of the infiltrating eosinophils in the affected esophageal tissue showed immunohistochemical staining with anti-eotaxin antibody. In blood samples, the free eotaxin level was slightly elevated before treatment, whereas the total eotaxin level was within the normal range. Unexpectedly, the total eotaxin level increased dramatically after the initiation of steroid therapy, whereas the increase of free eotaxin was modest. CONCLUSION: Infiltrating eosinophils that express eotaxin and the changes of blood eotaxin levels during steroid therapy suggest that eotaxin may be associated with IEE.

Chemokine CCL11↗

PubMed2002

Theoretical study of substitution effect of the hydrogen bond stability of 9-methylguanine derivatives and 1-methylcytosine.

The substitution effect on hydrogen bond stability of the Watson-Crick type base pair between 1-methylcytosine (C) and substitution-introduced 9-methylguanine derivatives (Gx) was studied by an ab initio molecular orbital theory. Introduction of an electron-withdrawing group on the 8-position or on the exo-cyclic amino moiety enforced the base pair stability.

Cytosine↗

PubMed2002

Regulation of voltage-dependent sodium channel expression in adrenal chromaffin cells: involvement of multiple calcium signaling pathways.

The density and electrical activity of cell surface voltage-dependent Na(+) channels are key determinants regulating the neuronal plasticity including development, differentiation, and regeneration. Abnormalities of Na(+) channels are associated with various neurological diseases. In this paper, we review the regulatory mechanisms of cell surface Na(+) channel expression mediated by Ca(2+) signaling pathways in cultured bovine adrenal chromaffin cells. Sustained, but not transient, elevation of intracellular Ca(2+) concentration reduced the number of cell surface Na(+) channels. The reduction of Na(+) channels was suppressed by an inhibitor of calpain, a Ca(2+)-dependent protease, and by an inhibitor of protein kinase C (PKC). The activation of conventional PKC-alpha and novel PKC-epsilon reduced cell surface Na(+) channels by the acceleration of internalization of the channels and by the increased degradation of Na(+) channel alpha-subunit mRNA, respectively. On the contrary, the activation of PKC-epsilon increased Na(+) channel beta(1)-subunit mRNA level. The inhibition of calcineurin, a Ca(2+)/calmodulin-dependent protein phosphatase 2B, by immunosuppressants upregulated cell surface Na(+) channels by both stimulating externalization and inhibiting internalization of the channels without changing Na(+) channel alpha- and beta(1)-subunit mRNA levels. Thus, the signal transduction pathways mediated by intracellular Ca(2+) modulate cell surface Na(+) channel expression via multiple Ca(2+)-dependent events, and the changes in the intracellular vesicular trafficking are the important mechanisms in the regulation of Na(+) channel expression.

Adrenal Glands↗

PubMed2002

Serum deprivation-induced upregulation of voltage-dependent sodium channels in adrenal chromaffin cells: selective involvement of extracellular signal-regulated kinase pathway.

In the present study, we investigated whether activation of the MAPK family could regulate the cell surface expression of Na channels in cultured bovine adrenal chromaffin cells. The results suggest that constitutively activated ERK (but not p38 or JNK), by various extracellular stimuli, down-modulates the density of cell surface Na channels, which was mediated via the destabilization of Na channel alpha-subunit mRNA.

Animals↗

PubMed2002

Down-regulation of cell surface insulin receptor and insulin receptor substrate-1 phosphorylation by inhibitor of 90-kDa heat-shock protein family: endoplasmic reticulum retention of monomeric insulin receptor precursor with calnexin in adrenal chromaffin cells.

Treatment (>/=6 h) of cultured bovine adrenal chromaffin cells with geldanamycin (GA) or herbimycin A (HA), an inhibitor of the 90-kDa heat-shock protein (Hsp90) family, decreased cell surface (125)I-insulin binding. The effect of GA was concentration (EC(50) = 84 nM)- and time (t(1/2) = 8.5 h)-dependent; GA (1 microM for 24 h) lowered the B(max) value of (125)I-insulin binding by 80%, without changing the K(d) value. Western blot analysis showed that GA (>/=3 h) lowered insulin receptor (IR) level by 83% (t(1/2) = 7.4 h; EC(50) = 74 nM), while raising IR precursor level by 100% (t(1/2) = 7.9 h; EC(50) = 300 nM). Pulse-label followed by reducing and nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that monomeric IR precursor (~190 kDa) developed into the homodimeric IR precursor (approximately 380 kDa) and the mature alpha(2)beta(2) IR (~410 kDa) in nontreated cells, but not in GA-treated cells; in GA-treated cells, the homodimerization-incompetent form of monomeric IR precursor was degraded via endoplasmic reticulum (ER)-associated protein degradation. Immunoprecipitation followed by immunoblot analysis showed that IR precursor was associated with calnexin (CNX) to a greater extent in GA-treated cells, compared with nontreated cells. GA had no effect on IR mRNA levels and internalization rate of cell surface IRs. In GA-treated cells, insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) was attenuated by 77%, with no change in IRS-1 level. Thus, inhibition of the Hsp90 family by GA or HA interrupts homodimerization of monomeric IR precursor in the ER and increases retention of monomeric IR precursor with CNX; this event retards cell surface expression of IR and attenuates insulin-induced activation of IRS-1.

Adrenal Glands↗

PubMed2002

[Regulation of brain microvessel function].

The brain microvessels are formed by a specialized endothelium and regulate the movement of solutes between blood and brain. The endothelial cells are sealed together by tight junctions and play a role as the blood-brain barrier. The brain microvessels express GLUT1 as the major form of glucose transporter, aquaporin-4 as a water channel, and p-glycoprotein as a xenobiotic transporter. Occludin and claudin-5 have been identified as the components of tight junction. Increasing evidence suggests that the activities of the transporters are regulated by adrenergic nerve activity as well as by bioactive peptides such as adrenomedullin. The regulation of the activity as well as expression of these transporters may become a strategy for prophylaxis and treatment of not only cerebral vascular diseases but also neurodegenerative disorders, developmental abnormalities and aging of the brain.

ATP Binding Cassette Transporter, Subfamily B, Mem↗