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Biomedical subjects

T Miyata

Publications and source records attributed to T Miyata.

At least 469 records · Page 26Linked to original sources
PubMed1992

Coagulation factor X activating enzyme from Russell's viper venom (RVV-X). A novel metalloproteinase with disintegrin (platelet aggregation inhibitor)-like and C-type lectin-like domains.

We determined the complete amino acid sequence of RVV-X, the blood coagulation factor X activating enzyme, isolated from Russell's viper venom and studied structure-function relationships. RVV-X (M(r) 79,000) consists of a disulfide-bonded two-chain glycoprotein with a heavy chain of M(r) 59,000 and a light chain of heterogeneous M(r) 18,000 (LC1) and 21,000 (LC2). These chains were separated after reduction and S-pyridylethylation, and the isolated major component LC1 was used for sequence analysis. The heavy chain consists of 427 residues containing four asparagine-linked oligosaccharides, and its entire sequence was similar to that of the high molecular mass hemorrhagic protein, HR1B, isolated from the venom of Trimere-surus flavoviridis. The heavy chain contains three distinct domains, metalloproteinase, disintegrin (platelet aggregation inhibitor)-like and unknown cysteine-rich domains. On the other hand, light chain LC1 consists of 123 amino acid residues containing one asparagine-linked oligosaccharide and shows sequence homology similar to that found in the so-called C-type (Ca(2+)-dependent) lectins. Therefore, RVV-X is a novel metalloproteinase containing a mosaic structure with distintegrin-like, cysteine-rich, and C-type lectin-like domains. RVV-X potently inhibits collagen- and ADP-stimulated platelet aggregations, probably via its distintegrin-like domain, although this domain does not contain the Arg-Gly-Asp sequence which is conserved in various venom distintegrins and which is thought to be one of the interaction sites for platelet integrins. Our findings also indicate that snake venom factor IX/factor X-binding protein with a C-type lectin structure (Atoda, H., Hyuga, M., and Morita, T. (1991) J. Biol. Chem. 266, 14903-14911) inhibits RVV-X-catalyzed factor X activation; hence, the light chain of RVV-X probably participates in recognizing some portion of the zymogen factor X.

Amino Acid Sequence↗
PubMed1992

Molecular cloning of dihydrolipoamide acetyltransferase of the rat pyruvate dehydrogenase complex: sequence comparison and evolutionary relationship to other dihydrolipoamide acyltransferases.

A complementary DNA (cDNA) clone of dihydrolipoamide acetyltransferase (E2) of the rat pyruvate dehydrogenase complex (PDC) was isolated from a lambda gt11 rat heart cDNA library. The amino acid sequence of a full mature protein of rat PDC-E2 was predicted by combination of the cDNA nucleotide sequence and the N-terminal amino acid sequence determined chemically. The amino acid sequence of rat PDC-E2 was well consistent with those of the E2 components of other alpha-ketoacid dehydrogenase complexes. These E2 components possess the sequence G-X-G-X-X-G, which is the consensus sequence for nucleotide binding sites of nucleotide binding proteins, in the E3 and/or E1 binding domains. The E2 components of the three alpha-ketoacid dehydrogenase complexes are suggested to be classified into three clusters separated during evolution.

Acetyltransferases↗
PubMed1992

Analysis of intrinsic fibrinolysis in human plasma induced by dextran sulfate.

The analysis of normal human plasma by fibrin autography revealed four species of plasminogen activator (PA) activity related to tissue-type PA, factor XII, prekallikrein and urokinase-type PA (u-PA). The u-PA activity increased significantly by incubating plasma with dextran sulfate. This increase was coincident with both the cleavage of factor XII and the complex formation of activated factor XII with its plasma inhibitors, which were determined by immunoblotting procedure. The dextran sulfate-dependent activation of u-PA required both factor XII and prekallikrein, but did not require either plasminogen or factor XI. High molecular weight kininogen was required only at a low concentration of dextran sulfate. Thus the results indicate that the factor XII and prekallikrein-mediated activation of single chain u-PA (scu-PA) operates as a major pathway of scu-PA activation in whole plasma in contact with dextran sulfate.

Dextran Sulfate↗
PubMed1992

Both beta 1- and beta 2-adrenoceptors are involved in mediating phosphatidylcholine secretion in rat type II pneumocyte cultures.

A primary culture of rat type II pneumocytes was used for the pharmacological and functional characterization of beta-adrenoceptor subtypes. The beta-adrenoceptor agonists, isoprenaline, dobutamine and procaterol concentration dependently increased the secretion of phosphatidylcholine. These effects were attenuated by propranolol. The effect of dobutamine was attenuated by atenolol, and that of procaterol by ICI 118,551. Isoprenaline-induced secretion was attenuated by the combination of the two blockers but not by each one alone. In conclusion, both beta 1- and beta 2-adrenoceptor subtypes mediate phosphatidylcholine secretion in rat type II pneumocytes.

Adrenergic beta-Agonists↗
PubMed1992

Interchromosomal gene conversion as a possible mechanism for explaining divergence patterns of ZFY-related genes.

The divergence pattern of mammalian ZFY-related genes from human (ZFY and ZFX) and mouse (Zfy-1 and Zfx) was reexamined on the basis of nucleotide substitutions at the synonymous codon-alternating positions. It is possible to explain the unusual divergence pattern of the mammalian Y-linked ZF genes by interchromosomal gene conversion by X-linked ZF genes. Furthermore, the rates of evolution of mammalian X- and Y-linked ZF genes were shown to agree well with those expected from our model.

Animals↗
PubMed1992

Pilonidal sinus on the neck.

A recurrent nuchal abscess was treated in a 21-year-old obese young man with a total excision of the lesion. In the histopathological findings, many similarities were found between this lesion and pilonidal sinus. We discuss the pathogenesis of this lesion, as well as our belief that this case was a rare example of pilonidal sinus on the neck.

Adult↗
PubMed1992

Surgical treatment of Takayasu arteritis.

From 1959 to 1991, 93 patients underwent vascular reconstruction for Takayasu arteritis at our institution. The details of the cases were as follows: 16 were of type I (brachiocephalic ischemia), 48 type II (hypertension), 13 type III (extensive lesions with cerebral ischemia and hypertension), and 16 type IV (aneurysms). Carotid reconstruction, repair of atypical aortic coarctation, renovascular reconstruction, and aneurysm repair were performed independently or in combination. Nine operative deaths occurred, 8 cases of which were operated before 1970. The most serious of the delayed complications was suture line aneurysm formation, which was encountered in ten cases. The aneurysms were often found long after the operation, some of them developing even after more than 20 years. Takayasu arteritis is characterized by extensive inflammation and destruction of the medial elastic fibers and long term postoperative observation is mandatory to improve the late survival rate.

Aortic Aneurysm↗
PubMed1992

Collagen engineering for biomaterial use.

Collagen is a typical biological macromolecule having been utilized for a long period of time as a material like cellulose. However, its application is becoming comprehensive, ranging from classical applications such as the leather, gelatine and food industries to the current one, namely, biomaterial and biotechnological uses. The diversification of collagen applications was enhanced by two factors, the accumulation of the scientific knowledge that permitted proper engineering of collagen for a biomaterial use, and the demand for new biomaterials with characteristic biological properties including interaction with cells. The collagen engineering described in this paper is designed for biomaterial use, based on the fundamental chemical and biological properties of collagen; however, it would be useful also for other applications apart from biomaterials.

Biocompatible Materials↗
PubMed1992

Preparation and properties of monoclonal antibodies against lipopolysaccharide-sensitive serine protease zymogen, factor C, from horseshoe crab (Tachypleus tridentatus) hemocytes.

Seventeen murine monoclonal antibodies (mAbs) against horseshoe crab clotting factor, factor C, were prepared and characterized. When the binding sites of these mAbs were analyzed by immunoblotting, ten mAbs recognized nonreduced factor C, five mAbs were directed against the heavy chain, and two mAbs were directed against the B chain. Three mAbs, 1H4, 2C12, and 2A7, one selected from each group, were used for further study. The mAb 1H4, which recognized only nonreduced factor C molecule, inhibited the factor C activity in a dose-dependent manner. It also inhibited lipopolysaccharide (LPS)- and alpha-chymotrypsin-mediated activations of the zymogen factor C, suggesting that 1H4 binds close to the active site and/or the substrate-binding site located in the serine protease domain (B chain) of factor C. On the other hand, 2C12 and 2A7 recognized, respectively, an epitope located in the heavy and the B chains, and inhibited LPS-mediated activation of factor C, but not alpha-chymotrypsin-mediated activation of factor C or factor C activity. Both F(ab')2 and Fab' fragments derived from 2C12 inhibited LPS-mediated activation in the same manner. These three mAbs did not bind with LPS, although a factor C-mAb complex was able to bind LPS, suggesting that the LPS-mediated activation of the zymogen factor C was induced through intermolecular interaction between the LPS-bound factor C molecules. The dissociation constants (Kd) for 1H4, 2C12, and 2A7 binding to factor C were determined as 1.9 x 10(-9), 0.6 x 10(-10), and 1.8 x 10(-10) M, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Production, purification, and characterization of botulinolysin, a thiol-activated hemolysin of Clostridium botulinum.

A hemolysin, botulinolysin, produced by Clostridium botulinum was purified to homogeneity and characterized. First, a strain of C. botulinum type C, strain C-203 Tox, which produced a large amount of hemolysin, was selected, and optimal culture medium and conditions for its production of hemolysin were determined. The hemolysin produced in the culture supernatant of this strain under optimal conditions was purified by a combination of ammonium sulfate precipitation, DEAE-Sepharose CL-6B column chromatography, Sephadex G-75 gel permeation chromatography, and SP-Toyopearl 650 M cation-exchange column chromatography, with a recovery of 12%. The purified hemolysin gave a single protein band in polyacrylamide gel electrophoresis (PAGE) with and without sodium dodecyl sulfate (SDS). The protein in this band in PAGE with SDS was estimated to have a molecular weight of 58,000 and was immunostained with a neutralizing monoclonal antibody. In PAGE without SDS, the hemolytic activity corresponded in position to the single protein band. The pI of the hemolysin was 8.4. Amino acid analysis of the purified hemolysin indicated the presence of four half-cystine residues per molecule. The purified hemolysin had a specific activity of 2,100 hemolytic units per microgram of protein on rabbit erythrocytes. It was activated by SH compounds, inhibited by cholesterol, and heat labile. The optimum pH for hemolysis was 6.0 to 7.0. Rabbit, human, and guinea pig erythrocytes were the most susceptible to the hemolysin, while sheep, mouse, rat, and chicken erythrocytes were much less susceptible. The purified hemolysin had a lethal effect in mice and was cytotoxic for some cultured cells: its 50% lethal dose in mice was 310 ng, and its 50% cytotoxic dose for Vero cells was 120 ng/ml.

Amino Acids↗
PubMed1992

Fluid-phase activation of the alternative pathway of complement by excess factor D in regularly dialyzed patients.

We examined the effect of excess factor D on the alternative pathway of complement (APC). First, we demonstrated that the production of C3a is accelerated in the fluid-phase with the addition of purified factor D. Analysis by sodium dodecylsulfate polyacrylamide gel electrophoresis under reducing conditions showed that the serum iC3b level was elevated when incubated with excess factor D. Secondly, we demonstrated, by measuring the C5a-des-Arg level, that the generation of C5a was promoted in the fluid-phase with the addition of purified factor D. We then studied whether activation of APC is elevated in the blood of patients on maintenance hemodialysis whose sera contained a high concentration of factor D. First, we detected, by fluorescence activated cell sorter analysis, greater amounts of C3d on erythrocytes from the patients (mean fluorescence intensity +/- SD: 7.7 +/- 1.7 arbitrary units) than those from healthy individuals (5.4 +/- 0.5 arbitrary units; p less than 0.001). Secondly, serum C3 level was significantly lower (p less than 0.001) in patients (mean +/- SD: 63.3 +/- 8.2 mg/dl) than in healthy individuals (84.8 +/- 9.5 mg/dl), whereas there was no difference in serum C4 level between patients (32.4 +/- 6.9 mg/dl) and healthy individuals (33.0 +/- 7.4 mg/dl). Serum C5 level was almost the same in patients (10.5 +/- 1.5 mg/dl) and in healthy individuals (11.2 +/- 1.3 mg/dl). These results provide supportive evidence of elevated APC activation in patients with high serum factor D.

Blood Circulation↗
PubMed1992

Removal of extracellular Mg2+ suppresses sulfation of glycoconjugates secreted from rabbit trachea in culture.

The influences of extracellular Ca2+ and Mg2+ concentrations on the basal secretion of glycoconjugates from rabbit trachea in organ culture were examined. Over 80% of the 35S-labeled and [3H]glucosamine-labeled glycoconjugates secreted by the trachea were digested upon incubation with chondroitinase ABC. The basal secretion did not occur in the medium at 4 degrees C, indicating an energy-dependent process. The basal secretion at 37 degrees C of 35S-labeled glycoconjugates was prominently suppressed in Mg(2+)-free Tyrode solution but not in Ca(2+)-free Tyrode solution containing ethyleneglycol bis(2-aminoethylether)tetraacetic acid (EGTA). In contrast, the basal secretion of [3H]glucosamine-labeled glycoconjugates was not affected by the Mg2+ concentration in the medium. The results suggest that extracellular Mg2+ largely contributes to sulfation of glycoconjugates basally secreted from rabbit trachea.

Animals↗
PubMed1992

Abnormalities in platelets and vascular endothelial cells induced by glycated lipoproteins.

We studied the effects of glycated lipoproteins of low- and high-density (LDL and HDL) on platelets and vascular endothelial cells. After pretreatment for 5 minutes at 37 degrees C, the thrombin-induced synthesis of thromboxane B2 in washed platelets was significantly increased by glycated LDL as compared with native LDL (198.9 +/- 16.2 vs 90.3 +/- 29.4 ng/10(9) platelets, n = 8, p less than 0.01). Platelet aggregation was also increased by glycated LDL as compared with native LDL. After treatment with platelet-rich plasma for 5 hours at 37 degrees C, these values were suppressed by native HDL vs the control (buffer), but not by glycated HDL. Abnormalities in the release of 6-keto prostaglandin F1 alpha and lactate dehydrogenase from vascular endothelial cells were also induced by glycated LDL and/or HDL. These observations suggest that abnormalities induced in platelets and vascular endothelial cells by glycated lipoproteins may play an important role in the development of atherosclerosis in patients with diabetes mellitus.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Human fibrinogen heterogeneity: the COOH-terminal residues of defective A alpha chains of fibrinogen II.

Fibrinogen fraction I (340 kDa) and fraction II (305 kDa) were isolated by glycine precipitation. The subunit chains of the two fractions were separated, after reduction, by reverse-phase high performance liquid chromatography. The amino acid compositions of the B beta and tau chains of fibrinogen II were identical with those of fibrinogen I. In contrast, the A alpha chains of fibrinogen II were composed of two populations, one comprising homogeneous, intact A alpha chains and the other consisting of heterogeneous, deficient A alpha chains (A alpha' chains) of lengths varying according to the sizes of their COOH-terminal defects. The molar ratio of the A alpha to the A alpha' chains in fibrinogen II was 1.16:1. The amino acid composition and sequence analyses of the TPCK-trypsin peptides derived from the A alpha' chains revealed that the COOH-terminal residues of the A alpha' chains were mainly Asn-269, Gly-297 and Pro-309. These results indicate that the fibrinogen II molecule is asymmetrical and can be represented by the formula (A alpha) (A alpha')(B beta)2(tau)2 and that fibrinogen II cannot be a plasmin degradation product of fibrinogen I.

Amino Acid Sequence↗
PubMed1992

Interleukin-1 receptor antagonist in inflammatory exudate cells of rabbits. Production, purification and determination of primary structure.

A rabbit interleukin-1 (IL-1) inhibitor in inflammatory peritoneal exudate cells was purified to apparent homogeneity. This inhibitor was extracted from exudate cells of the 24-hr stage of casein-induced peritoneal inflammation and purified using isoelectrofocusing (IEF), gel filtration, followed in this order by high-performance liquid chromatography (HPLC) steps with hydroxylapatite and anionic ion exchanger. The purified factor showed a single band on silver-stained SDS-PAGE. This molecule of MW 19,000 and pI 5.5 inhibited the binding of both IL-1 alpha and beta to receptors on a thymoma cell line, EL-4 and a B-cell line, 70Z/3. We determined its primary structure by a combination of peptide chemistry and molecular cloning. The inhibitor was synthesized as a precursor composed of 177 amino acids and was processed to a mature molecule of 143 amino acids. The N-terminal amino acid of the mature inhibitor was N-acetyl-methionine residue. The deduced amino acid sequence of the inhibitor showed a 77% homology to the human IL-1 receptor antagonist (IL-1Ra) and essentially the same mode of action as seen with human IL-1Ra. We consider that this inhibitor is a rabbit counterpart of human IL-1Ra, although there are differences with respect to the molecular structure; the N-terminus of the mature rabbit IL-1Ra at a position of nine amino acids downstream from that of human IL-1Ra.

Amino Acid Sequence↗
PubMed1992

[Operative strategy for thoracoabdominal aortic aneurysm with concomitant reconstruction of four main abdominal branches].

A thoracoabdominal aortic aneurysm (TAAA) involving major abdominal branches remains still difficult to be managed. From 1983 to 1990, we successfully operated five such cases. Our operative strategy for TAAA which necessitates concomitant reconstruction of four major abdominal branches is i) to utilize temporary bypass to maintain distal perfusion during aortic cross-clamping, ii) to reconstruct bilateral renal arteries prior to aortic clamping in order to shorten renal ischemic time as much as possible, iii) to reconstruct celiac and superior mesenteric arteries by Crawford's method, iv) to reconstruct two pairs of intercostal arteries by using diagonal anastomosis in the proximal site, and v) to divide the left renal vein temporarily for easy manipulation of renal arteries. All five cases were recovered uneventfully. This procedure, in which the renal ischemic time is saved as short as possible, is considered a safe and reasonable one for thoracoabdominal aortic aneurysms.

Adult↗
PubMed1992

Effects of excess factor D on early- and late-phase activation of the complement cascade.

The present study was undertaken to examine the effects of excess factor D build-up in the body of end-stage renal disease (ESRD) patients upon the activation of the alternative pathway and the terminal pathway in the fluid phase. First, to clarify the effect of excess factor D on the alternative pathway, purified factor D from an ESRD patient was added to normal serum and the changes in concentrations of C3a-des-Arg and C5a-des-Arg were investigated. The results showed that once the serum factor D level reached a concentration corresponding to 15 micrograms/ml in the serum of the ESRD patient, the C3a-des-Arg and C5a-des-Arg levels had climbed to about 1.7-fold the concentration in normal serum. Next, in order to clarify the effect of excess factor D on the terminal pathway, purified factor D was added to normal serum, and the changes in C5b6 generation were examined. The results indicated that as the factor D level increased in the serum, the C5b6 level rose gradually also; and when the factor D concentration reached 15 micrograms/ml, the C5b6 generation had risen to approximately 1.5-fold the level in normal serum. The present results therefore suggest that factor D build-up in ESRD patients provides a uremic toxin that can cause abnormal activation of the whole complement cascade.

Complement Activating Enzymes↗