Search PubMed⌕ Search

Biomedical subjects

T Miyata

Publications and source records attributed to T Miyata.

At least 199 records · Page 11Linked to original sources
PubMed1999

Expression of megsin mRNA, a novel mesangium-predominant gene, in the renal tissues of various glomerular diseases.

Mesangial cells play an important role in maintaining a structure and function of the glomerulus and in the pathogenesis of glomerular diseases. Recently, we discovered a new mesangium-predominant gene termed "megsin." Megsin is a novel protein that belongs to the serine protease inhibitor (serpin) superfamily. To elucidate the pathophysiologic role of megsin in the kidney, the expression and localization of megsin mRNA in renal tissues of patients with IgA nephropathy (IgA-N), diabetic nephropathy (DN), minimal change nephrotic syndrome (MCNS), membranous nephropathy (MN), and normal human kidney (NHK) was evaluated by in situ hybridization using digoxigenin-labeled oligonucleotide. Individual cells positive for megsin mRNA were observed only in glomeruli in all renal tissues. Their localization coincided with those of mesangial cells. The percentage of positive cells for megsin mRNA in total glomerular cells was significantly greater in IgA-N than in MCNS, MN, and NHK. It was also significantly greater in DN than in MCNS and NHK. In IgA-N, the percentage of megsin mRNA-positive cells was greater in tissues from those with mesangial cell proliferation and slightly mesangial matrix expansion (periodic acid-Schiff-positive area in the total glomerulus area, <30%; cell number in mesangial matrix area, >30; assessed in cross-sections through their vascular poles) than in tissues from those with severe mesangial matrix expansion (periodic acid-Schiff-positive area in total glomerulus area, >30%; cell number in mesangial matrix area, <30). In conclusion, megsin mRNA was predominantly expressed in glomerular mesangial cells in all renal tissues. The expression of megsin mRNA was upregulated in IgA-N and DN, both of which are diseases accompanied with mesangial cell proliferation and/or mesangial matrix expansion. These data suggest a link of megsin expression to the pathogenesis of IgA-N and DN, two major causes of end-stage renal failure.

Actins↗
PubMed1999

Immunohistochemical evidence for an increased oxidative stress and carbonyl modification of proteins in diabetic glomerular lesions.

Advanced glycation end products (AGE) include a variety of protein adducts whose accumulation has been implicated in tissue damage associated with diabetic nephropathy (DN). It was recently demonstrated that among AGE, glycoxidation products, whose formation is closely linked to oxidation, such as carboxymethyllysine (CML) and pentosidine, accumulate in expanded mesangial matrix and nodular lesions in DN, in colocalization with malondialdehyde-lysine (MDA-lysine), a lipoxidation product, whereas pyrraline, another AGE structure whose deposition is rather independent from oxidative stress, was not found within diabetic glomeruli. Because CML, pentosidine, and MDA-lysine are all formed under oxidative stress by carbonyl amine chemistry between protein amino group and carbonyl compounds, their colocalization suggests a local oxidative stress and increased protein carbonyl modification in diabetic glomerular lesions. To address this hypothesis, human renal tissues from patients with DN or IgA nephropathy were examined with specific antibodies to characterize most, if not all, carbonyl modifications of proteins by autoxidation products of carbohydrates, lipids, and amino acids: CML (derived from carbohydrates, lipids, and amino acid), pentosidine (derived from carbohydrates), MDA-lysine (derived from lipids), 4-hydroxynonenal-protein adduct (derived from lipids), and acrolein-protein adduct (derived from lipids and amino acid). All of the protein adducts were identified in expanded mesangial matrix and nodular lesions in DN. In IgA nephropathy, another primary glomerular disease leading to end-stage renal failure, despite positive staining for MDA-lysine and 4-hydroxynonenal-protein adduct in the expanded mesangial area, CML, pentosidine, and acrolein-protein adduct immunoreactivities were only faint in glomeruli. These data suggest a broad derangement in nonenzymatic biochemistry in diabetic glomerular lesions, and implicate an increased local oxidative stress and carbonyl modification of proteins in diabetic glomerular tissue damage ("carbonyl stress").

Adult↗
PubMed1999

Apolipoprotein E2/E5 variants in lipoprotein glomerulopathy recurred in transplanted kidney.

Lipid abnormalities are associated with various disorders ranging from generalized atherosclerosis to renal diseases, including lipoprotein glomerulopathy that is characterized by glomerular lipoprotein thrombi and causes type III hyperlipoproteinemia, proteinuria, and renal failure. This study examines lipoprotein glomerulopathy, which recurred in a transplanted kidney. Molecular biologic analysis of the patient's apolipoprotein (apo) E gene demonstrated E2/E5 type variants. Immunohistochemical analysis of the diseased kidney demonstrated various lipid peroxidation-specific protein adducts, suggesting a potential role of oxidative stress in this disorder. Recurrence in the transplanted kidney suggested a pathogenic role of extraglomerular humoral component(s) resulting from abnormal lipoprotein metabolism, presumably linked to apo E and other genetic or acquired factor(s). Furthermore, the finding that the patient showed pathologic abnormalities in the transplanted kidney with no clinical signs or symptoms of renal disease indicated that lipoprotein glomerular damage progresses early before any clinical manifestations.

Adult↗
PubMed1999

Carbonyl stress in the pathogenesis of diabetic nephropathy.

Diabetic nephropathy is a major chronic complication of diabetes mellitus and an important cause of increased morbidity and mortality in diabetic patients. Although several lines of evidence have suggested that poor glycemic control undoubtedly plays a significant role, the metabolic events responsible for its development are not understood well. Possible mediators of untowards effects of hyperglycemia include the advanced glycation end products (AGEs). AGEs, carboxymethyllysine and pentosidine, whose formation is closely linked to oxidation, accumulate in the characteristic diabetic glomerular lesions, such as the expanded mesangial matrix and nodular lesions, in co-localization with other oxidation-specific protein adducts, such as malondialdehyde-lysine, 4-hydroxynonenal-protein adduct, and acrolein-protein adduct. These five biomarkers are formed under oxidative stress by carbonyl amine chemistry between protein amino group and carbonyl compounds derived from carbohydrates, lipids, and amino acids. This article focuses on new aspects of the pathology of diabetic nephropathy, implicating an increased oxidative stress and carbonyl modification of proteins by autoxidation products of carbohydrates, lipids, and amino acids in diabetic glomerular tissue damage ("carbonyl stress").

Amino Acids↗
PubMed1999

Increase in the advanced glycation end product pentosidine in Bruch's membrane with age.

PURPOSE: To determine whether there is an age-related increase of pentosidine in human Bruch's membranes and to localize pentosidine and carboxymethyllysine (CML), two well-characterized, advanced glycation end products (AGEs) in aged human Bruch's membranes and choroid in vivo. METHODS: Human Bruch's membrane samples were isolated from the retinal pigment epithelium (RPE) and choroid and subjected to reversed-phase high-performance liquid chromatography to determine pentosidine content. A polyclonal anti-pentosidine antibody and a monoclonal antibody specific for carboxymethyllysine were used to localize AGEs in 20-month-old nondiabetic, 82-year-old nondiabetic, and 82-year-old diabetic globes. RESULTS: Human Bruch's membranes (n = 20) showed a linear age-dependent increase in pentosidine that reached approximately 0.17 millimoles pentosidine per mole hydroxyproline in late life (r = 0.896; P < 0.001). Immunohistochemical evaluation showed evidence of pentosidine in Bruch's membrane, choroidal extracellular matrix, and vessel walls in the 82-year-old nondiabetic and diabetic globes. A similar staining pattern was found with the anti-CML antibody. Basal laminar deposits and drusen stained with both antibodies in the elderly nondiabetic eye. In contrast, neither antibody stained the 20-month-old tissue. CONCLUSIONS: We provide biochemical and immunohistochemical evidence for the formation of pentosidine and CML structures in human Bruch's membrane and choroid with age. These changes could promote aging of the RPE-Bruch's membrane-choroid complex.

Adult↗
PubMed1999

Age- and sex-related differences of plasma activated factor VII levels in children.

Although the majority of factor VII (FVII) circulates in the zymogen form, low levels of activated factor VII (FVIIa) exist in plasma and play an important role in the initiation of tissue factor-induced coagulation. It has been reported that the concentrations of hemostatic components in children and adults are different. Here, we investigated the age- and sex-related differences of FVIIa and FVII antigen (FVIIag) levels in children at age of 10 (n = 123; males: n = 62; females: n = 61), and 13 (n = 105; males: n = 47: females: n = 58), and compared these levels with those of young adults (mean +/- SD of age: 29.6+/-6.0 years). In males, there was not a significant difference between the FVIIIa levels of 10-year-old children and 13-year-old children, but the FVIIa levels in adult controls were significantly higher than those in children. In females, the FVIIa levels in 13-year-old children were significantly higher than that in 10-year-old children, but there was not a significant difference between 13-year-old children and adults. Thus, our study showed that plasma FVIIa levels were lower in children than in adults, and the increase of FVIIa level was earlier in females than in males.

Adolescent↗
PubMed1999

Carbonyl stress: increased carbonyl modification of tissue and cellular proteins in uremia.

Advanced glycation end-products (AGEs) are formed during non enzymatic glycation and oxidation (glycoxidation) reactions. This process is accelerated in diabetics owing to hyperglycemia, and it has been implicated in the pathogenesis of diabetic complications. Surprisingly, AGEs increase in normoglycemic uremic patients to a much greater extent than in diabetics. AGE accumulation in uremia cannot be attributed to hyperglycemia nor simply to a decreased removal by glomerular filtration. Recently gathered evidence has suggested that, in uremia, the increased carbonyl compounds derived from carbohydrates and lipids modify proteins not only by glycoxidation reaction but also by lipoxidation reaction ("carbonyl stress"). Carbonyl stress has been implicated in the pathogenesis of long-term uremic complications such as dialysis-related amyloidosis. With regard to continuous ambulatory peritoneal dialysis (CAPD), the peritoneal cavity appears to be in a state of severe overload of carbonyl compounds derived from CAPD solution containing high glucose, from heat sterilization of the solution, and from uremic circulation. Carbonyl stress might modify not only peritoneal matrix proteins and alter their structures, but also react with mesothelial and endothelial cell surface proteins and initiate a range of inflammatory responses. Carbonyl stress might therefore contribute to the development of peritoneal sclerosis in patients with long-term CAPD.

Aldehydes↗
PubMed1999

Beta2-microglobulin and renal bone disease.

Dialysis-related amyloidosis (DRA) is characterized by amyloid deposition mainly in bone and joint structures, presenting as carpal tunnel syndrome, destructive arthropathy, and subchondral bone erosions and cysts. Beta2-microglobulin has been demonstrated to be a major constituent of amyloid fibrils. DRA occurs not only in patients undergoing long-term hemodialysis, but also in patients undergoing continuous ambulatory peritoneal dialysis. The incidence of this complication increases with the duration of dialytic therapy and the age of the patient. While a definitive diagnosis of DRA can be made only by histological findings, various imaging techniques often support diagnosis. The molecular pathogenesis of this complication remains unknown. Recent studies have, however, suggested a pathogenic role of a new modification of beta2-microglobulin in amyloid fibrils--that is, the advanced glycation end-products (AGEs) formed with carbonyl compounds derived from autoxidation of both carbohydrates and lipids ("carbonyl stress"). Therapy for DRA is limited to symptomatic approaches and surgical removal of amyloid deposits. High-flux biocompatible dialysis membranes could be used to delay DRA development.

Amyloid↗
PubMed1999

Nondissection method in distal arterial bypass surgery.

One of the most conspicuous advances in vascular surgery during the past two decades has been the improvement of the patency of distal bypasses. The nondissection method, in particular, has made a great contribution to better the tibioperoneal bypass patency. This review describes the operative procedure and background of the method, in which only the vascular sheath of the recipient artery is exposed and circumferential dissection of the artery avoided. The limb is exsanguinated with an Esmarch's bandage, and haemostasis is maintained with a pneumatic tourniquet. Vascular clamps are not applied to the artery at the distal anastomotic site. In a series of 42 tibial bypasses, a primary revised patency of 84% has been achieved after five years with this method.

Anastomosis, Surgical↗
PubMed1999

Comparison of near-infrared spectroscopy with air plethysmography in detection of deep vein thrombosis.

BACKGROUND: As a noninvasive screening test, air plethysmography (APG) is a reliable and frequently used modality in the detection of deep vein thrombosis (DVT). Although APG is highly sensitive for the diagnosis of proximal DVT, its sensitivity for identifying calf DVT is poor. Near-infrared spectroscopy (NIRS) is a new modality which can be used to evaluate venous retention during walking. The purpose of this study was to investigate the diagnostic value of NIRS for the detection of DVT, particularly isolated calf DVT, in comparison with APG. METHODS: Fifty limbs of 39 consecutive patients with clinically suspected DVT were studied. All patients were examined by venography and APG. Patients also underwent a treadmill-walking test with simultaneous NIRS. Deoxygenated hemoglobin was continuously measured by NIRS during exercise. The ambulatory venous retention index obtained from serial DeoHb changes was calculated in each patient. RESULTS: Venography demonstrated DVT in 35 limbs, confined to the calf in 9 limbs, and with the involvement of a proximal deep vein with thrombi in 26. The overall sensitivity of NIRS and APG was 97% (34/35) and 80% (28/35), respectively. NIRS was more sensitive than APG for detecting isolated calf DVT (89% [8/9] and 22% [2/9], respectively), while both tests identified proximal DVT in all limbs. CONCLUSIONS: NIRS is a highly sensitive method for the diagnosis of haemodynamically significant DVT. NIRS may become a useful screening test because of its reliability in detecting calf vein thrombi that cannot be identified by APG.

Female↗
PubMed1998

The complete nucleotide sequence of the human immunoglobulin heavy chain variable region locus.

The complete nucleotide sequence of the 957-kb DNA of the human immunoglobulin heavy chain variable (VH) region locus was determined and 43 novel VH segments were identified. The region contains 123 VH segments classifiable into seven different families, of which 79 are pseudogenes. Of the 44 VH segments with an open reading frame, 39 are expressed as heavy chain proteins and 1 as mRNA, while the remaining 4 are not found in immunoglobulin cDNAs. Combinatorial diversity of VH region was calculated to be approximately 6,000. Conservation of the promoter and recombination signal sequences was observed to be higher in functional VH segments than in pseudogenes. Phylogenetic analysis of 114 VH segments clearly showed clustering of the VH segments of each family. However, an independent branch in the tree contained a single VH, V4-44.1P, sharing similar levels of homology to human VH families and to those of other vertebrates. Comparison between different copies of homologous units that appear repeatedly across the locus clearly demonstrates that dynamic DNA reorganization of the locus took place at least eight times between 133 and 10 million years ago. One nonimmunoglobulin gene of unknown function was identified in the intergenic region.

Chromosomes, Artificial, Yeast↗
PubMed1998

When overexpressed, a novel centrosomal protein, RanBPM, causes ectopic microtubule nucleation similar to gamma-tubulin.

A novel human protein with a molecular mass of 55 kD, designated RanBPM, was isolated with the two-hybrid method using Ran as a bait. Mouse and hamster RanBPM possessed a polypeptide identical to the human one. Furthermore, Saccharomyces cerevisiae was found to have a gene, YGL227w, the COOH-terminal half of which is 30% identical to RanBPM. Anti-RanBPM antibodies revealed that RanBPM was localized within the centrosome throughout the cell cycle. Overexpression of RanBPM produced multiple spots which were colocalized with gamma-tubulin and acted as ectopic microtubule nucleation sites, resulting in a reorganization of microtubule network. RanBPM cosedimented with the centrosomal fractions by sucrose- density gradient centrifugation. The formation of microtubule asters was inhibited not only by anti- RanBPM antibodies, but also by nonhydrolyzable GTP-Ran. Indeed, RanBPM specifically interacted with GTP-Ran in two-hybrid assay. The central part of asters stained by anti-RanBPM antibodies or by the mAb to gamma-tubulin was faded by the addition of GTPgammaS-Ran, but not by the addition of anti-RanBPM anti- bodies. These results provide evidence that the Ran-binding protein, RanBPM, is involved in microtubule nucleation, thereby suggesting that Ran regulates the centrosome through RanBPM.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Genetic analysis of protein C deficiency in nineteen Japanese families: five recurrent defects can explain half of the deficiencies.

We have been studying the molecular basis of protein C deficiency. In this study, we determined the molecular defects of protein C deficiency in 19 Japanese families by using a strategy combining polymerase chain reaction (PCR) and single-strand conformational polymorphism (SSCP) analysis. We identified 10 missense mutations, 1 in-frame deletion, 1 frameshift deletion, 1 frameshift addition, and 1 splice site mutation, 5 of which were novel. From the results of genetic analysis of 67 Japanese families with protein C deficiency reported in this and previous studies, the recurrent defects including Phe139Val and Met365Ile substitutions and a Lys150 d letion, a G8857 deletion, and a splice site mutation of G3079A were only found in Japanese subjects and seemed to be a founder effect. In contrast, Arg169Trp, Arg286His, Val297Met, and Asp359Asn substitutions, all occurring at CG dinucleotides, were commonly observed in not only Japanese but also Western populations, indicating that these are hot spots for mutation in the protein C gene. These 9 recurrent molecular defects were found in 43 families in total, accounting 64% of Japanese families with protein C deficiency. In particular, the recurrent defects of Phe139Val, Arg169Trp, Va1297Met, and Met36-4Ile substitutions and a G8857 deletion were found in 33 families in total, accounting for 49% of Japanese families with protein C deficiency. For the identification of the genetic defect in Japanese patients with protein C deficiency, screening of these recurrent defects by using restriction enzyme cleavage is a rational method.

Exons↗
PubMed1998

Phospholipase C cDNAs from sponge and hydra: antiquity of genes involved in the inositol phospholipid signaling pathway.

To know whether or not the set of genes involved in the inositol phospholipid signaling pathway already existed in the early evolution of animals, we carried out cloning of cDNAs encoding phospholipase Cs (PLCs) from Ephydatia fluviatilis (freshwater sponge) and Hydra magnipapillata strain 105 (hydra). We isolated two PLC cDNAs, PLC-betaS and PLC-gammaS, from sponge and three cDNAs, PLC-betaH1, PLC-betaH2, and PLC-deltaH, from hydra. From the domain organization and the divergence pattern in the PLC family tree, the sponge PLC-betaS and PLC-gammaS and the hydra PLC-deltaH are possibly homologous to the vertebrate PLC-beta, PLC-gamma and PLC-delta subtypes, respectively. A detailed phylogenetic analysis suggests that the hydra PLC-betaH1 and PLC-betaH2 are homologs of the vertebrate PLC-beta1/2/3/Drosophila PLC21 and the vertebrate PLC-beta4/Drosophila norpA, respectively. A phylogenetic analysis of the PLC family and the protein kinase C (PKC) family, together with that of the G protein alpha subunit (Galpha) family, revealed that the origin of the set of genes G(alpha)q, PLC, PKC involved in the inositol phospholipid signaling pathway is very old, going back to dates before the parazoan-eumetazoan split, the earliest branching among extant animal phyla.

Animals↗
PubMed1998

Level of HgCl2-mediated phosphorylation of intracellular proteins determines death of thymic T-lymphocytes with or without DNA fragmentation.

Exposure to Hg2+ at a wide range of concentrations (approximately 1-100 microM) more or less caused the death of murine thymic T-lymphocytes, and exposure to 1 microM but not 10 microM (or more) of Hg2- induced DNA fragmentation. Exposure of cells to Hg2+ caused phosphorylation of multiple cellular proteins at the tyrosine residue in a concentration-dependent manner. We found that not only the DNA fragmentation induced by 1 microM Hg2+ but also the cell death bypassing DNA fragmentation caused by 10 microM or more Hg2+ was partly inhibited by protein kinase inhibitors such as staurosporine and herbimycin A. This result suggested the involvement of a protein phosphorylation-linked signal in the mechanism of the Hg2+-mediated cell death with or without DNA fragmentation. Analysis of proteins by both one- and two-dimensional electrophoresis and immunoblot showed that a 52-kDa Shc protein was heavily phosphorylated by an early signal delivered by a high concentration of Hg2+, which also phosphorylated extracellular signal-regulated kinase 1 (ERK1; p44) and ERK2 (p42) of the mitogen-activated protein kinase (MAPK) family in a concentration- and time-dependent manner. The c-Jun amino terminal kinase (p54), which is a distant relative of the MAPK family, was also phosphorylated by the treatment with Hg2+. This eventually formed the signaling cascade that ended with a nuclear target by phosphorylating c-jun at the serine 73. This phosphorylation of c-jun was inhibited by staurosporine. These results suggest that a high level of Hg2+-mediated protein phosphorylation-linked signal induces rapid cell death bypassing DNA fragmentation, whereas a lower level induces cell death accompanying DNA fragmentation. This conclusion in turn implies that DNA fragmentation is not always a prerequisite for the signal transduction-dependent cell death of T-lymphocytes.

Animals↗