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T Miyata

Publications and source records attributed to T Miyata.

At least 271 records · Page 15Linked to original sources
PubMed1997

Disruption of hippocampal development in vivo by CR-50 mAb against reelin.

We previously generated a monoclonal alloantibody, CR-50, by immunizing reeler mutant mice with homogenates of normal embryonic brains. This antibody recently was shown to recognize a Reelin protein, which is coded by the recently identified candidate gene for the reeler mutation. However, it is still unclear whether Reelin, especially the CR-50 epitope region, is indeed responsible for the reeler phenotype in vivo. Here we show that Reelin is localized on Cajal-Retzius neurons in the hippocampus and that intraventricular injection of CR-50 at the embryonic stage disrupts the organized development of the hippocampus in vivo, converting it to a reeler pattern. Labeling experiments with 5-bromodeoxyuridine demonstrated that the labeled cells in the stratum pyramidale of the CR-50-treated mice were distributed in a pattern similar to that of reeler. Thus, Cajal-Retzius neurons play a crucial function in hippocampus development, and the CR-50 epitope on Reelin plays a central role in this function.

Animals↗
PubMed1997

Immunohistochemical localization of advanced glycation end products, pentosidine, and carboxymethyllysine in lipofuscin pigments of Alzheimer's disease and aged neurons.

Lipofuscins are intracellular fluorescent pigments accumulating in the central nervous system (CNS) with aging and degenerative processes such as Alzheimer's disease (AD). Although they are thought to be lipid peroxidation products derived from malondialdehyde, their biogenesis remains controversial. We further characterize the chemical nature of lipofuscins in brain tissues from AD patients and normal aged subjects. Advanced glycation end products (AGEs), pentosidine and carboxymethyllysine (CML), were identified by appropriate specific antibodies. They have physicochemical properties similar to those of lipofuscin and also increase with aging. Pentosidine and CML were identified in the neuronal perikarya and the extraneuroperikaryal deposits of both the AD and aged brain. Pentosidine, but not CML, was present in the fiber-like structure within the neuropil and the core of classical senile plaque. In the brain of young subjects without CNS disease, pentosidine and CML staining was faint. Pentosidine and CML co-localized with lipofuscin pigments in the neuronal perikarya of both the AD and aged brain. We demonstrate for the first time that lipofuscin is constituted not only of lipid peroxidation products but also from glycation products which may be the origin of fluorescent pigments. Lipofuscins should thus be considered as fluorescent pigments generated by lipid- and sugar-derived Schiff base-protein polymers.

Adolescent↗
PubMed1997

Protein modification by a Maillard reaction intermediate methylglyoxal. Immunochemical detection of fluorescent 5-methylimidazolone derivatives in vivo.

Methylglyoxal (MG), an endogenous metabolite that increases in diabetes, is a common intermediate in nonenzymatic glycation (Maillard reaction) in vivo. Here we describe the immunochemical approach to the detection of MG adducts in proteins in vitro and in atherosclerotic lesions of human aorta in vivo. The reaction of protein (bovine serum albumin) with MG led to selective loss of arginine and lysine residues, accompanied by the formation of 5-methylimidazolone (N delta-(5-methylimidazolon-2-yl)ornithine) and imidazolysine (1,3-di-lysino-4-methylimidazole) derivatives, respectively. The anti-5-methylimidazolone antibody was prepared by immunizing rabbits with a MG-keyhole limpet hemocyanin conjugate and purifying the serum on an affinity gel prepared by covalent attachment of the 5-methylimidazolone derivative. The antibody cross-reacted with the proteins treated with not only MG but trioses, such as hydroxyacetone, dihydroxyacetone, and glyceraldehyde. The immunohistochemical analysis revealed that atherosclerotic lesions of human aorta contained 5-methylimidazolone derivatives whose distributions were identical to those of advanced glycation end products (AGEs) detected by the anti-AGE antibody.

Animals↗
PubMed1997

Differential effect of codeine on coughs caused by mechanical stimulation of two different sites in the airway of guinea pigs.

We studied the difference in the effects of codeine on coughs caused by mechanical stimulation to the larynx and to the bifurcation of the trachea in lightly anaesthetized guinea pigs. Mechanical stimulation to the larynx or the bifurcation of trachea caused a stable cough response. The response was reproducible over 60 min, when stimulation was repeatedly applied at 20-min intervals. No significant difference was found between the amplitudes of the responses to mechanical stimulation of the larynx and of the tracheal bifurcation. Codeine, 10, 20 and 50 mg/kg, dose dependently depressed the coughs caused by larynx stimulation. The antitussive, however, failed to depress the cough caused by stimulation to the tracheal bifurcation, although a large dose, 50 mg/kg, significantly depressed the cough. In capsaicin-treated guinea pigs, codeine at 20 mg/kg significantly depressed the cough caused by stimulation to the tracheal bifurcation. The present results suggest that cough caused by mechanical stimulation to the larynx might be more sensitive to codeine treatment than cough caused by stimulation to the bifurcation of trachea. Furthermore, it is suggested that coughs caused by mechanical stimulation to both sites might consist of at least two components as regards their pharmacological nature.

Animals↗
PubMed1997

Regulation of Purkinje cell alignment by reelin as revealed with CR-50 antibody.

Cerebellar Purkinje cells are generated in the ventricular zone, migrate outward, and finally form a monolayer in the cortex. In reeler mice, however, most Purkinje cells cluster abnormally in subcortical areas. Reelin, the candidate reeler gene product recognized by the CR-50 monoclonal antibody, is concentrated in a cortical zone along which Purkinje cells are aligned linearly, implying that it may regulate their alignment. We used an in vitro system and a transplantation approach to analyze the function of Reelin. Explant culture for 7 d of cerebella isolated from wild-type and reeler mice at embryonic day 13 (E13) reproduced in a phenotype-dependent manner the two distinct arrangement patterns (linear vs clustered) of Purkinje cells. Extensive CR-50 binding to wild-type explants converted the linear pattern into a reeler-like, clustered pattern. On the other hand, when reeler explants lacking Reelin were crowned with an artificial layer of Reelin+ granule cells, some Reelin molecules were distributed into a superficial zone of the reeler explants, and Purkinje cells formed a linear pattern along the Reelin-rich overlay. This "rescue" effect was also inhibited by CR-50. Hence, Reelin is involved in the Purkinje cell alignment, and the lack of this activity may explain the malformation in reeler cerebella. We further injected Reelin+ granule cells into the fourth ventricle of E12-13 mice. Extensive incorporation of the injected Reelin+ cells into the ventricular zone, but not of Reelin- cells, forced Purkinje cells of the host cerebella to form an aberrant layer, suggesting that premigratory Purkinje cells may already be responsive to Reelin or Reelin-related signals.

Animals↗
PubMed1997

Caenorhabditis elegans has two isozymic forms, CE-1 and CE-2, of fructose-1,6-bisphosphate aldolase which are encoded by different genes.

Two distinct types of cDNAs for fructose-1,6-bisphosphate (FBP) aldolase, Ce-1 and Ce-2, have been isolated from nematode Caenorhabditis elegans, and the respective recombinant aldolase isozymes, CE-1 and CE-2, have been purified and characterized. The Ce-1 and Ce-2 are 1282 and 1248 bp in total length, respectively, and both have an open reading frame of 1098 bp, which encodes 366 amino acid residues. The entire amino acid sequences deduced from Ce-1 and Ce-2 show a high degree of identity to one another and to those of vertebrate and invertebrate aldolases. The highest sequence diversity was found in the carboxyl-terminal region that corresponds to one of the isozyme group-specific sequences of vertebrate aldolase isozymes that play a role in determining isozyme-specific functions. Southern blot analysis suggests that CE-1 and CE-2 are encoded by different genes. Concerning general or kinetic properties, CE-2 is quite different from CE-1. CE-1 exhibits unique characteristics which are not identical to any aldolase isozymes previously reported, whereas CE-2 is similar to vertebrate aldolase C. These results suggest that CE-2 might preserve the properties of a progenitor aldolase with a moderate preference for FBP over fructose 1-phosphate (F1P) as a substrate, whereas CE-1 evolved to act as an intrinsic enzyme that exhibits a much broader substrate specificity than dose CE-2.

Amino Acid Sequence↗
PubMed1997

Cloning of human and mouse cDNAs encoding novel zinc finger proteins expressed in cerebellum and hippocampus.

We identified a novel gene, kf-1, highly expressed in the normal cerebellum but not in the cerebral cortex, the expression of which could have been augmented in the cerebral cortex of a sporadic Alzheimer's disease patient. We cloned human and mouse entire kf-1 cDNAs encoding conserved 79 kDa proteins containing a zinc-binding RING-H2 finger motif at the carboxy-terminus as found in acetylcholine receptor-associated protein (RAPsyn). The 3'-untranslated regions are highly conserved between human and mouse as to constitute a common mRNA secondary structure. In situ hybridization analysis of mouse brain sections revealed strong kf-1 expression in the cerebellum and hippocampus. We propose that KF-1 is involved in membranous protein-sorting apparatus similarly to RAPsyn. We mapped the human kf-1 gene to 2p11.2.

Alzheimer Disease↗
PubMed1997

Rapid postincubation endothelial retention by Dacron grafts.

Defining the most appropriate conditions for strengthening the retention of endothelial cells (ECs) by small-diameter prosthetic endothelialized grafts is indispensable to their clinical application. The incubation time after seeding is one of the most important factors in EC retention. The effects of different postincubation times (0, 2, 4, 8, 16, 24, and 36 hr) on EC monolayers on two different types of graft, fibronectin-coated expanded polytetrafluoroethylene (ePTFE) and collagen-coated knitted Dacron grafts (4 mm x 5 cm) were examined. In situ counting of ECs on the grafts was performed by light microscopy. The percentage cell retention was calculated by dividing the cell counts for grafts exposed to pulsatile flow for 90 min by those for control grafts. To characterize the EC coverage of the grafts, scanning electron microscopy was also performed. The average cell density of control grafts ranged from 5.59 +/- 1.1 to 6.69 +/- 1.5 x 10(4) cells/cm2 and did not differ according to the kind of graft or incubation time. The knitted Dacron grafts showed the maximal cell retention (88 +/- 5%) after incubation for 8 hr, whereas ePTFE grafts did so after 24 hr (83 +/- 6%). Scanning electron microscopic examination after incubation for 8 hr revealed that the density of human ECs on the surfaces of ePTFE and Dacron grafts differed, although there was no morphological difference between the ECs on the two types of graft. Knitted Dacron grafts achieved a high percentage retention in a shorter time than ePTFE grafts.

Blood Vessel Prosthesis↗
PubMed1997

A role for Cajal-Retzius cells and reelin in the development of hippocampal connections.

During development of the nervous system, specific recognition molecules provide the cues necessary for the formation of neural connections. In some regions, guiding cues for axonal pathfinding and target selection are provided by specific cells that exist only transiently during development, such as the floorplate or the cortical subplate. In the hippocampus, distinct groups of fibres innervate different layers. We have tested the hypothesis that transient neurons in the hippocampus provide positional information for the targeting of these fibres. Here we report that ablation of Cajal-Retzius cells in organotypic slice cultures of hippocampus prevented the ingrowth of entorhinal but not of commissural afferents. Experiments inhibiting Reelin (an extracellular matrix protein expressed by Cajal-Retzius cells) and analysis of reeler mutant mice showed dramatic abnormalities in the development of entorhinal afferents. Thus Cajal-Retzius cells and reelin are essential for the formation of layer-specific hippocampal connections.

Animals↗
PubMed1997

Reelin is a secreted glycoprotein recognized by the CR-50 monoclonal antibody.

The neurological mouse mutant strain reeler displays abnormal laminar organization of several brain structures as a consequence of a defect in cell migration during neurodevelopment. This phenotype is a result of the disruption of reelin, a gene encoding a protein that has several structural characteristics of extracellular matrix proteins. To understand the molecular basis of the action of Reelin on neuronal migration, we constructed a full-length reelin clone and used it to direct Reelin expression. Here, we demonstrate that Reelin is a secreted glycoprotein and that a highly charged C-terminal region is essential for secretion. In addition, we demonstrate that an amino acid sequence present in the N-terminal region of Reelin contains an epitope that is recognized by the CR-50 monoclonal antibody. CR-50 was raised against an antigen expressed in normal mouse brain that is absent in reeler mice. The interaction of CR-50 with its epitope leads to the disruption of neural cell aggregation in vitro. Here, we used CR-50 to precipitate Reelin from reticulocyte extracts programmed with reelin mRNA, from cells transfected with reelin clones, and from cerebellar explants. The reelin gene product seems to function as an instructive signal in the regulation of neuronal migration.

Animals↗
PubMed1997

An estimate of divergence time of Parazoa and Eumetazoa and that of Cephalochordata and Vertebrata by aldolase and triose phosphate isomerase clocks.

Previously we suggested that four proteins including aldolase and triose phosphate isomerase (TPI) evolved with approximately constant rates over long periods covering the whole animal phyla. The constant rates of aldolase and TPI evolution were reexamined based on three different models for estimating evolutionary distances. It was shown that the evolutionary rates remain essentially unchanged in comparisons not only between different classes of vertebrates but also between vertebrates and arthropods and even between animals and plants, irrespective of the models used. Thus these enzymes might be useful molecular clocks for inferring divergence times of animal phyla. To know the divergence time of Parazoa and Eumetazoa and that of Cephalochordata and Vertebrata, the aldolase cDNAs from Ephydatia fluviatilis, a freshwater sponge, and the TPI cDNAs from Ephydatia fluviatilis and Branchiostoma belcheri, an amphioxus, have been cloned and sequenced. Comparisons of the deduced amino acid sequences of aldolase and TPI from the freshwater sponge with known sequences revealed that the Parazoa-Eumetazoa split occurred about 940 million years ago (Ma) as determined by the average of two proteins and three models. Similarly, the aldolase and TPI clocks suggest that vertebrates and amphioxus last shared a common ancestor around 700 Ma and they possibly diverged shortly after the divergence of deuterostomes and protostomes.

Amino Acid Sequence↗
PubMed1997

Comparative strengths of metal framework structures for removable partial dentures.

STATEMENT OF PROBLEM: The framework of removable partial dentures often breaks where the metal retention for the resin denture base attaches to the clasp and major connector. PURPOSE: To study these failure factors, various types of three-dimensional simulated denture frameworks were designed to measure their ultimate strengths and stiffnesses under static load. This study also sought to determine which could be recommended for long-term clinical service. MATERIAL AND METHODS: Three groups of three-dimensional frameworks (double, T-shaped, and trussed structure) were designed, and two groups of classic framework designs (uniform and nonuniform skeleton) were used with an acrylic resin block as a control (n = 5 per group). Fatigue strength, stiffness and amount of strain, and free-end displacement under dynamic loads were measured for each framework. The fatigue strength was determined with a constant-loading fatigue test by counting the number of loading cycles required to induce catastrophic failure. RESULTS: With 20 kgf of load, four T-shaped samples and three trussed structure samples failed at 30,000 to 60,000 loading cycles. No samples of double structure group failed until 100,000 loading cycles. CONCLUSIONS: Three-dimensional frameworks, especially the double structure, have significant differences in fatigue strength and can provide long-term clinical service.

Chromium Alloys↗
PubMed1997

Adenovirus-mediated transfer of tissue-type plasminogen activator gene to human endothelial cells.

BACKGROUND: Seeding of vascular grafts with genetically engineered human endothelial cells (hECs) secreting antithrombogenic or fibrinolytic agents has considerable clinical potential. METHODS: An adenoviral vector was used to transfer the human tissue-type plasminogen activator (htPA) gene to hECs, and the ability of the transduced hECs to secrete htPA was examined. Cultured hECs on plates were incubated with various concentrations of recombinant adenoviruses containing the htPA or LacZ gene for various times to determine the optimal transfer conditions. Transduced hECs were seeded onto fibronectin-coated expanded polytetrafluoroethylene grafts (4 mm in diameter), some of which were exposed to pulsatile flow in vitro. RESULTS: Effective transduction of the htPA gene into hECs (htPAhECs) was achieved with viral soup at a multiplicity of infection of 30 after incubation for 1 day, which yielded 4.8 +/- 0.20 x 10(3) ng/10(6) cells/6 hr htPA antigen on plates (n = 3), 2.2 +/- 2.0 x 10(3) ng/10(6) cells/6 hr on grafts (n = 6), and 6.8 +/- 1.7 x 10(2) ng/10(6) cells/6 hr on perfused grafts (n = 6). The retention of htPAhECs by perfused grafts was 84.0% +/- 3.0%, comparable with the noninfected (82.1% +/- 8.0%) and mock-infected (94.2% +/- 0.4%) hEC values. CONCLUSIONS: By adenoviral vector-mediated gene transfer, 10(2-3)-fold enhancement of htPA secretion was demonstrated, which did not affect cell retention by grafts.

Adenoviridae↗
PubMed1997

Ruptured abdominal aorta secondary to psoas muscle abscess due to Klebsiella pneumoniae in an alcoholic.

An alcoholic patient with low back pain and Klebsiella pneumoniae septicaemia is reported. Computed tomography revealed abdominal aortic rupture associated with a psoas abscess. Aortic ligation above and below the rupture site and an axillo-femoral bypass were performed, but the patient died on the first postoperative day. Alcoholism is a common underlying disease in K. pneumoniae septicaemia and its septic metastasis to the psoas muscle. The prognosis of aortic infection secondary to psoas abscess is very poor once aortic rupture occurs. Prompt abscess drainage following correct diagnosis and arterial reconstruction before aortic rupture are mandatory.

Adult↗
PubMed1997

A novel neurological mutant mouse, yotari, which exhibits reeler-like phenotype but expresses CR-50 antigen/reelin.

We present yotari, a novel neurological mutant mouse whose mutation is transmitted in an autosomal recessive manner. The phenotype of yotari is very similar to that of reeler. yotari mutants are recognizable by their unstable gait and tremor and by their early deaths at around the time of weaning. The cerebella of homozygous yotari are hypoplastic and have no foliation. A molecular and a granular cell layer can be identified, but Purkinje cells are scattered throughout both the granular layer and white matter. The laminar structure of the cerebral cortex and the hippocampal formation are also distorted. To test whether the mutated gene in yotari is the reeler gene, reelin, yotari heterozygotes were mated with reeler homozygotes or heterozygotes. The absence of abnormal offspring indicated that the yotari gene is distinct from reelin. Furthermore, expression of mRNA and protein of reelin was verified by Northern blotting and immunohistochemistry using a CR-50 monoclonal antibody (mAb) which is specific to Reelin, the reelin gene product. Although the mutation of several genes, including cyclin-dependent kinase 5 (Cdk 5), p35 and LIS1, 45 kDa subunits of platelet-activating factor acetylhydrolase (PAF-AH) Ib, in Miller-Dieker lissencephaly syndrome (MDS) has been reported to cause abnormal laminar structure in the brain, no abnormality was found in yotari by Western blotting with antibodies (Ab's) against these molecules. The close similarity of the phenotypes of yotari and reeler and the expression of reelin in yotari may suggest that the gene mutated in yotari encodes a molecule that is on the same signaling pathway as Reelin, the product of reelin. yotari will provide valuable clues to explore the molecular mechanism of neuronal migration and orderly laminar structure formation of the brain.

Animals↗
PubMed1997

Intraoperative evaluation of small-calibre arterial reconstructions.

A new hammerhead-shaped, small probe for intraoperative duplex ultrasound was devised to evaluate small-calibre arterial reconstructions. This probe was used in two patients; one with terminal liver cirrhosis who had a left hepatic lobe that had been transplanted from her mother, and a second patient with limb-threatening ischaemia who had undergone arterial reconstructions. The technique was diagnostically useful and contributed to successful clinical outcomes.

Adolescent↗
PubMed1997

Clearance of pentosidine, an advanced glycation end product, by different modalities of renal replacement therapy.

We recently demonstrated that pentosidine, an advanced glycation end product, accumulates markedly as albumin-linked form (Palb) and in free-form (Pfree) in the plasma of patients with end-stage renal failure. The present study was undertaken to examine the clearance of Palb and Pfree by different modalities of renal replacement therapy, that is, hemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD), and renal transplantation. HD cleared Pfree (9.4 +/- 4.3 nmol/kg/HD) but not Palb, by diffusion but not by membrane adsorption, whereas CAPD cleared both Palb (4.03 +/- 2.01 nmol/kg/day) and Pfree (2.43 +/- 1.24 nmol/kg/day). Plasma total pentosidine levels were significantly (P < 0.05) lower in CAPD (0.97 +/- 0.41 nmol/ml) than in HD (1.19 +/- 0.41 nmol/ml), as the result of a lower serum albumin level in the former patients. Indeed, Palb expressed per mg albumin was virtually identical in HD and CAPD. By contrast, Pfree was significantly lower in CAPD than in HD. Palb levels were significantly correlated with plasma Pfree levels in both HD and CAPD patients, but not in the CAPD dialysate. Pentosidine transport across the peritoneum occurs mainly by diffusion, both as Palb and Pfree. Interestingly, peritoneal Palb clearance (0.17 +/- 0.07 ml/min) significantly (P < 0.00001) exceeded albumin clearance (0.11 +/- 0.05 ml/min). Palb levels being significantly higher (P < 0.0005) in the peritoneal fluid (36.28 +/- 18.55 pmol/mg) than in the serum (27.12 +/- 11.71 pmol/mg), thus raises the possibility of a facilitated diffusion of Palb or an active transport mechanism for protein-linked pentosidine into the peritoneal cavity. After renal transplantation, plasma Pfree fell rapidly, remained barely detectable after one month, and returned to normal at six months. By contrast, Palb fell more slowly and remained significantly above normal at six months, but returned eventually to normal levels. These findings demonstrate that: (1) both HD and CAPD remove Pfree; (2) the peritoneal clearance of Palb, might contribute to the lower level of plasma pentosidine in CAPD than in HD patients; and (3) renal transplantation is the best therapeutic modality to normalize both Palb and Pfree levels.

Adult↗