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Biomedical subjects

T Miyata

Publications and source records attributed to T Miyata.

At least 451 records · Page 25Linked to original sources
PubMed1993

Motifs of cadherin- and fibronectin type III-related sequences and evolution of the receptor-type-protein tyrosine kinases: sequence similarity between proto-oncogene ret and cadherin family.

Immunoglobulin (Ig)-, fibronectin type III (FN-III)-, and cadherin-related sequences are often found in multiple repeats in the extracellular regions of various cell adhesion molecules. The amino acid sequences of 82 different cadherin-like repeats from 13 known members of the cadherin superfamily were compared for six highly conserved regions, and a frequency matrix represented as amino acids versus position matrix was calculated based on the alignment. With the frequency matrix, further members of the cadherin superfamily were searched for in the protein data base. It was found that the ret protein, a receptor-type-protein tyrosine kinase, contains cadherin-like repeats in the extracellular region. A similar analysis was also carried out for the FN-III superfamily. Nine receptor-type-protein tyrosine kinases were shown to exhibit significant similarities, in terms of sequence, with known FN-III-like repeats. Several receptor-type-protein tyrosine kinases have already been reported to have Ig-like repeats in their extracellular regions. Thus these receptor-type-protein tyrosine kinases--together with the remaining receptors, whose structures are not yet characterized--may be classified into at least four distinct groups based on the structural differences in the extracellular domains. A molecular phylogenetic tree inferred from the shared kinase domains of these receptor-type-protein tyrosine kinases revealed a close relationship between the branching patterns and the grouping based on the structural differences of the extracellular region.

Amino Acid Sequence↗
PubMed1993

Gene transfer of a part of a beta-lactamase gene?

beta-Lactamase is an enzyme which catalyzes the hydrolysis of the beta-lactam ring of penicillins and cephalosporins. By similarity analysis of amino acid sequences in a database, the amino acid sequence deduced from the nucleotide sequence of the upstream region of cytochrome c oxidase subunit II from Paracoccus denitrificans was found to have an unusually high score of homology to that of a portion of beta-lactamases from Gram-negative bacteria. Furthermore, the nucleotide sequences corresponding only to this region had a very high score of similarity among them. The phylogenetic tree constructed on the basis of the amino acid sequences was in accord with that constituted on the 5S rRNA's. Moreover, the molar G + C contents and the codon usage were similar to those in their respective bacteria. It is suggested, therefore, that the nucleotide sequence in P. denitrificans was positioned by a transfer of a part of a beta-lactamase gene formed as a result of gene duplication or it was formed by a deletion of the essential region of the beta-lactamase gene, although no beta-lactamase gene has been yet detected in P. denitrificans.

Amino Acid Sequence↗
PubMed1993

Differences in the mode of cough augmentation by four angiotensin-converting enzyme inhibitors in guinea-pigs.

The effects of four angiotensin-converting enzyme (ACE) inhibitors, captopril, enalapril, quinapril and alacepril, on the cough responses caused by citric acid and capsaicin inhalation were studied in normal and bronchitic guinea-pigs. After an oral dose of 10 mg kg-1, none of the ACE inhibitors had an effect on the citric acid-induced coughing response in normal guinea-pigs. Enalapril 10 mg kg-1 significantly increased the number of coughs caused by capsaicin inhalation. In bronchitic guinea-pigs, 10 mg kg-1 captopril and enalapril significantly increased the number of capsaicin-induced coughs. When administered daily for 8 days, captopril was the only ACE inhibitor which significantly increased the number of coughs due to citric acid inhalation. The present results indicate that the ACE inhibitors had different modes of cough augmentation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1993

beta 2-Microglobulin modified with advanced glycation end products is a major component of hemodialysis-associated amyloidosis.

beta 2-Microglobulin (beta 2M) is a major constituent of amyloid fibrils in hemodialysis-associated amyloidosis, a complication of long-term hemodialysis patients. Amyloid fibril proteins were isolated from connective tissues forming carpal tunnels in hemodialysis patients with carpal tunnel syndrome. Two-dimensional polyacrylamide gel electrophoresis and Western blotting demonstrated that most of the beta 2M forming amyloid fibrils exhibited a more acidic pI value than normal beta 2M. This acidic beta 2M was also found in a small fraction of beta 2M in sera and urine from these patients, whereas heterogeneity was not observed in healthy individuals. We purified acidic and normal beta 2M from the urine of long-term hemodialysis patients and compared their physicochemical and immunochemical properties. Acidic beta 2M, but not normal beta 2M, was brown in color and fluoresced, both of which are characteristics of advanced glycation end products (AGEs) of the Maillard reaction. Immunochemical studies showed that acidic beta 2M reacted with anti-AGE antibody and also with an antibody against an Amadori product, an early product of the Maillard reaction, but normal beta 2M did not react with either antibody. Incubating normal beta 2M with glucose in vitro resulted in a shift to a more acidic pI, generation of fluorescence, and immunoreactivity to the anti-AGE antibody. The beta 2M forming amyloid fibrils also reacted with anti-AGE antibody. These data provided evidence that AGE-modified beta 2M is a dominant constituent of the amyloid deposits in hemodialysis-associated amyloidosis.

Amyloidosis↗
PubMed1993

Physarum vitronectin-like protein has extensive homology to dihydrolipoamide acetyltransferase.

Physarum vitronectin-like protein with a molecular mass of 70 kDa cross-reacts with anti-bovine vitronectin and promotes cell-spreading (Miyazaki, K. et al. 1992. Exp. Cell Res., 199: 106-110.). The amino-terminal sequence of Physarum vitronectin-like protein is, however, distinct from those of animal vitronectins but shows significant sequence homology with dihydrolipoamide acetyltransferase, a component of pyruvate dehydrogenase complex. We have investigated the structural relationships between Physarum vitronectin-like protein and dihydrolipoamide acetyltransferase by using both antibody and protein-chemical methods. The vitronectin-like protein reacted with both anti-bovine vitronectin IgG and anti-rat pyruvate dehydrogenase complex IgG, indicating that it shares common antigenic determinant(s) with rat pyruvate dehydrogenase complex. Furthermore, sequencing studies of peptides obtained by lysylendopeptidase digestion indicated that internal sequences of Physarum vitronectin-like protein show significant homology with dihydrolipoamide acetyltransferase, but do not show any homology with the primary structures of authentic vitronectins. Immunocytochemistry revealed that the protein is widely localized in cytoplasm and nuclei of Physarum polycephalum, but is not present in the central area of vacuoles. Our results indicate that Physarum vitronectin-like protein is a molecule structurally and immunologically related to dihydrolipoamide acetyltransferase but functionally similar to animal vitronectin, although its localization is unique.

Acetyltransferases↗
PubMed1993

[Effects of local anesthetics on rat macrophage phagocytosis].

We examined whether phagocytosis by macrophages (M phi s) is affected by local anesthetics (lidocaine HCl, prilocaine HCl, mepivacaine HCl, tetracaine HCl and procaine HCl). Opsonized zymosan, fetal bovine serum and one local anesthetic were added to each M phi sample. After a 30-min incubation, M phi s were washed to make Giemsa stained slides for counting. The phagocytosis rate was calculated by counting the phagocytosizing M phi s per 200 cells with an optical microscope, and rates for the samples containing local anesthetics were compared with those for the non-treated samples. Inhibition of phagocytosis was reversible, dose-dependent and pH dependent for all local anesthetics. Tetracaine HCl inhibited phagocytosis most and procaine HCl, least. These results suggest that local anesthetics at the level of clinical use inhibit leukocyte phagocytosis and therefore may interfere with the normal function of cells fundamental to host defense.

Anesthetics, Local↗
PubMed1993

[Method for evaluating pulmonary clearance in mice and its pharmacological applications].

The purpose of this study was to develop a method for evaluating pulmonary clearance in mice that inhaled aerosolized 99mTc-labeled human serum albumin (33mTc-HSA). Mice were ventilated with an aerosol of 99mTc-HSA for 10 min with an ultrasonic nebulizer in an acrylic chamber. Pulmonary clearance was estimated from lung retention ratio at various times after inhalation of 99mTc-HSA. Lung retention ratios in mice were 72.4 +/- 3.3% at 1 hr, 60.1 +/- 2.3% at 3 hr and 34.8 +/- 2.0% at 24 hr after inhalation of 99mTc-HSA, similar to the previous results obtained in humans by cinescintigraphy. The data were analyzed on the basis of two-compartment model. Mabuterol, a beta 2-adrenoceptor agonist, stimulated the pulmonary clearance. In contrast, metyrapone, an adrenal 11-beta steroid hydroxylase inhibitor, suppressed the clearance with a decreased corticosterone content in plasma. These findings suggest that the developed method is useful for evaluating the pharmacological effects on pulmonary clearance.

Adrenergic beta-Agonists↗
PubMed1993

[The utility of endoscopic ultrasonography (EUS) in endoscopic mucosal resection of early gastric cancer].

The utility of EUS was evaluated in 27 patients with early gastric cancer undergoing endoscopic mucosal resection over the past 2 years. Accuracy of the assessment of depth of cancerous invasion was studied in 16 patients undergoing EUS before endoscopic mucosal resection. Patients showing no changes in the submucosal (sm) layer or below on EUS included 15 with mucosal (m) cancer and one with sm cancer showing very slight infiltration. Seven patients with m cancer, a negative stump, and no ulcer in the cancer focus at endoscopic mucosal resection, were followed up for more than 1 year after endoscopic mucosal resection. On EUS, four patients showed Ul-IIs changes resembling benign ulcers, two showed Ul-IIIs changes and two showed no changes in the sm layer or below. All patients were negative for cancer in follow up biopsies. No lymphadenopathy was observed. EUS was effective in diagnosing the depth of cancerous invasion in patients undergoing endoscopic mucosal resection and also in clarifying changes in the sm and deeper layers during follow up.

Aged↗
PubMed1993

Inhibitory effect of FUT-175 on complement activation and its application for glomerulonephritis with hypocomplementemia.

FUT-175 (6-amidino-2-naphthyl p-guanidinobenzoate dimethane-sulphonate), a potent serine protease inhibitor, has been reported to inhibit complement activity in vitro, and especially the classical complement pathway effectively. In the present study, we examined the inhibitory effect of FUT-175 on the classical complement pathway components by hemolytic assay using purified human complement components. As a result, 50% inhibition of the C1 protease activity for classical C3 convertase formation and for C2 was obtained with 3.0 x 10(-8) M and 7.0 x 10(-8) M of FUT-175, respectively. FUT-175 did not inhibit the C2 protease activity at all. We then administered FUT-175 to 5 glomerulonephritic patients with hypocomplementemia and proteinuria in order to assess the clinical effectiveness of this drug. When FUT-175 was administered intravenously and continuously at a rate of 0.1 to 0.2 mg/kg/hr for 2 weeks, the urinary protein excretion decreased significantly from 2.9 +/- 0.8 to 1.4 +/- 0.5 g/day (P < 0.025). In these patients, some of the serum complement markers (serum C3, C4 level and the hemolytic activity via the classical complement pathway (CH50)) were increased after FUT-175 administration. The above findings suggests that FUT-175 can exert beneficial effects on glomerulonephritis with hypocomplementemia by inhibiting complement activation.

Adult↗
PubMed1993

[Examination of cholangiogram of obstructive jaundice using MRI--compared with PTC and ERCP].

PTC and ERCP are most often used in diagnosis of obstructive jaundice. We studied the possibility of clinical diagnosis using MRI in 33 cases of obstructive jaundice. A clinical diagnosis of malignant tumors could be given in 17 cases out of 20 (85%) using MRI if respiratory standstill was possible. An MRI cholangiogram was particularly effective in describing tearful parting bile ducts and was clearer than PTC in describing negative gallbladders. Choledochal stones could be diagnosed in 58% of cases, which was less than the rate for malignant tumors. MRI is not an invasive examination, can be used in diagnosis of obstructive jaundice, and helps in selecting treatment methods such as PTCD and ERBD.

Adult↗
PubMed1993

[Changes in high energy phosphates and tissue blood flow in ischemia and reperfusion of jaundiced rat liver--effect of intermittent brief ischemia].

This study was focused on the changes of high energy phosphates and tissue blood flow (TBF) in ischemia and reperfusion, of jaundiced rat liver. We ligated and cut the bile duct of male Wistar rats to induce jaundice. The rats were divided into two groups, BDL-4W which had ligation four weeks before examination and control which had no ligation. Two studies were performed; In study A, ischemia was induced by clamping portal vein and hepatic artery for 60 minutes. In study B, 15 minutes of ischemia was repeated four times with intervals of 10 minutes of reperfusion. A: 1) In BDL-4W, ATP was significantly lower than that in control at pre-ischemia and reperfusion. Recovery ratios (RR) of ATP in BDL-4W were significantly lower than those in control. 2) RR or TBF in BDL-4W were significantly lower than those in control. 3) In BDL-4W, xanthine was significantly higher than that in control at reperfusion. B: 4) There were no significant differences in the RR of ATP after reperfusion between two groups. 5) There were no significant differences in the RR of TBF between two groups. 6) There were no significant differences in xanthine after reperfusion between two groups. We concluded that intermittent brief ischemia was useful when 60 minutes of ischemia was required for the operation of jaundiced liver.

Adenosine Triphosphate↗
PubMed1993

Prolonged lung edema formation during the generalized Shwartzman reaction in rabbits--can it be a model for septic lung disease?

Pulmonary edema formation and the role of polymorphonuclear leukocytes (PMN) was evaluated during the generalized Shwartzman reaction (GSR) model in rabbits. Chemiluminescence (CL) and superoxide (O2-) production activity stimulated by FMLP were measured in circulating PMN after a single intravenous injection of endotoxin (E. coli 026:B6, 40 micrograms/kg) (E1). CL peaked at 36 hr after E1 injection and then decreased gradually to a normal range within 7 days. O2- production changed in a similar fashion. On the other hand, the PMN count peaked at 72 hr and remained at a high value until day 7. To induce GSR, a second venous injection of endotoxin (40 micrograms/kg) (E2) was administered 36 hr after the first one (E1). Four times as many PMN were observed in the lung capillaries 4 hr after the second endotoxin injection than after the first endotoxin injection (4 hr). The degree of lung edema formed increased after E2, but did not increase after E1. An alveolar hyaline-like exudate was observed 24 hr after E2. A continuous intravenous injection of superoxide dismutase (SOD) plus catalase or PMN depletion, prevented the development of post-E2 lung edema. If E2 was given 7 days after E1, no lung edema formed at all. These data indicate that oxygen free radicals from activated PMN by endotoxin play an important role in prolonged lung edema formation in the GSR model.

Animals↗
PubMed1992

Expression of human soluble tissue factor in yeast and enzymatic properties of its complex with factor VIIa.

The extracellular domain of human tissue factor (TF, amino acids 1-217) was expressed in Saccharomyces cerevisiae, using the inducible yeast acid phosphatase promoter and the yeast invertase signal sequence to direct its secretion into the culture broth. Two active soluble forms sTF alpha (high molecular weight form) and sTF beta (low molecular weight form) were purified, the yield being approximately 10 and 1 mg/liter of culture supernatant, respectively. sTF alpha had an apparent molecular mass of 150 kDa on SDS-polyacrylamide gel electrophoresis and contained more than 200 residues of mannose/mol of protein. sTF beta had an apparent molecular mass of 37 kDa and contained 22 residues of mannose/mol of protein. N-Glycosidase F treatments of both rTFs reduced the apparent molecular mass to 35 kDa. The amino-terminal sequences and amino acid compositions of sTF alpha and sTF beta were consistent with those deduced from the cDNA sequence, thereby indicating that the difference in molecular mass is caused by heterogeneity of oligosaccharide structures. Of these recombinant TFs, sTF beta enhanced factor VIIa-amidolytic activity 40-fold toward the chromogenic substrate and 147-fold toward the fluorogenic substrate, affecting mainly the kcat value. The enhancement was comparable with that of TF purified from human placenta. The TF-mediated enhancement of factor VIIa-amidolytic activity was inhibited by heparin-activated antithrombin III, forming a high molecular weight complex. As treatment of sTF beta with denaturants such as guanidine hydrochloride or urea led to a biphasic loss of the activity, the extracellular domain of TF probably consists of two discrete domains. This expression system provides a significant amount of the extracellular domain of TF so that studies of interactions with factor VII are feasible.

Amino Acid Sequence↗
PubMed1992

Molecular mechanism of hemolymph clotting system in Limulus.

Limulus (horseshoe crab) hemolymph is known to be very sensitive to bacterial endotoxin (LPS), which causes a rapid coagulation response. Hemolymph contains a single type of hemocyte that undergoes aggregation, adhesion, and degranulation in response to LPS. The granule contents are released into the hemolymph, where they form an insoluble gel. We have characterized four components involved in this coagulation response that comprise a cascade of three serine protease zymogens (factor C, factor B, and proclotting enzyme) and one clottable protein (coagulogen). Of these components, factor C sensitive to LPS is a protein composed of five complement-related domains ("Sushi" or SCR), an EGF-like domain, and a C-type lectinlike domain as well as a putative amino-terminal LPS-binding domain. This domain structure is very similar to that of selectin family of cell adhesion molecules, suggesting that it might also function as a cell adhesion molecule after the release into the hemolymph. Factor B and the proclotting enzyme share a common Cys-rich motif ("cliplike" domain) in the amino-terminal portions. This domain is also found in a putative serine protease zymogen ("easter") in Drosophila, which is essential for normal embryonic development. All four of the components of the cascade and an antibacterial protein (anti-LPS factor) are localized to a specific type of the hemocyte granule. Another antibacterial peptide (tachyplesins I and II) is localized in a distinct granule population. The contents of both granule populations are released into the hemolymph in response to LPS, where they cooperate in immobilization and killing of Gram-negative bacteria.

Amino Acid Sequence↗
PubMed1992

The influence of neuraminidase treatment on tracheal smooth muscle contraction.

To examine the role of sialic acid in the respiratory tract, the influence of neuraminidase from Clostridium perfringens was investigated on contractions of isolated guinea-pig and rat trachea and on histamine release from guinea-pig lung tissue. Treatment with 2.0 units/ml of neuraminidase at 37 degrees C and pH 7.4 for 30 min caused an approximately 60% removal of total N-acetylneuraminic acid, a representative sialic acid, from muscle from guinea-pig and rat trachea. Neuraminidase concentration dependently induced histamine release from guinea-pig chopped lung tissue, but has no effect on contractions produced by acetylcholine, histamine and 5-hydroxytryptamine. Pretreatment with 2.0 units/ml of neuraminidase inhibited the contraction induced by antigen (ovalbumin) or compound 48/80. These findings suggest, at least in part, that sialic acids sensitive to neuraminidase are involved in the regulation of histamine release but not tracheal contraction.

Acetylcholine↗
PubMed1992

Prothrombin Salakta: substitution of glutamic acid-466 by alanine reduces the fibrinogen clotting activity and the esterase activity.

Structural studies on a hereditary abnormal prothrombin, prothrombin Salakta, have been performed to identify the difference responsible for its reduced fibrinogen clotting activity and its reduced esterase activity. Amino acid composition and sequence analyses of a peptide isolated from a lysylendopeptidase digest of the abnormal thrombin indicated that Glu-466 had been replaced by Ala. This amino acid substitution can result from a single nucleotide change in the codon for Glu-466 (GAG----GCG). The model building and the molecular dynamics simulation of thrombin Salakta suggest that the Glu-466----Ala substitution would change the proper conformation around the substrate binding site containing Trp-468, which is a unique surface loop on the thrombin molecule. This is the experimental and theoretical evidence supporting the role of the surface loop containing Trp-468 for the proper conformation of the substrate binding site.

Alanine↗