Biomedical subjects

K Miyazawa

Publications and source records attributed to K Miyazawa.

At least 163 records · Page 9Linked to original sources

PubMed1995

[Molecular biology in cardiovascular medicine].

Molecular biology has given a strong impact on cardiovascular medicine, not only clinical but also laboratory medicine. cDNA cloning and analysis of gene structures encoding functional proteins or peptides in the cardiovascular system provided insight into molecular mechanisms underlying heart diseases or atherosclerosis. Nucleotide or amino acid sequences for these molecules are useful information for manufacturing bioactive peptides or developing immunoassays. These cDNA clones or genes are useful molecular tools diagnosing patients with high risks for cardiovascular diseases. Recent advances in this field have been made in identification of point mutations of many genes important for cardiovascular functions, including LDL receptors in familial hyperlipidemia, cardiac myosin heavy chain genes in familial hypertrophic cardiomyopathy, mitochondrial DNA in mitochondria cardiomyopathy, or dystrophin genes in secondary cardiomyopathy. Molecular probes are further used in detection of microorganisms causing myocarditis. These progresses that have been made in laboratories of basic researchers will be introduced into clinical medicine and expand the field the laboratory medicine is involved.

Cardiovascular Diseases↗

PubMed1994

Prostaglandin E2 levels in uterine tissues and its relationship with uterine and luteal progesterone during the estrous cycle in dairy cows.

Endometrial tissue homogenates obtained at luteal and follicular stages of the estrous cycle were determined for prostaglandin E2 and progesterone contents by EIA and RIA, respectively. In Experiment 1, the concentrations and changes of PGE2 in uterine tissues collected by biopsy before slaughter and subsequent samples collected at 30, 60 and 90 min after slaughter were measured. No significant differences were observed in the concentration of PGE2 preslaughter or at 30 and 60 min post slaughter. However, there was a significant decrease (P<0.01) in PGE2 concentration 90 min post slaughter. In Experiment 2, the concentrations of PGE2 in the ipsilateral and contralateral horns in relation to corpus luteum function were compared. A significant (P<0.05) interaction was found between stages of estrous cycle (luteal vs follicular) based on CL progesterone content, and type of uterine horn (ipsilateral vs contralateral) on uterine PGE2 levels. The PGE2 concentration was significantly higher (P<0.01) at luteal phase than at follicular phase. During the luteal phase PGE2 concentrations in tissues of the uterine horn ipsilateral to the corpus luteum was significantly higher (P<0.01) than the contralateral horn. The PGE2 concentration was low and did not differ significantly between horns during follicular phase. A parallel increase (luteal: high) and decrease (follicular: low) in PGE2 and progesterone concentrations were observed. Correlations were observed for CL progesterone and uterine PGE2 concentrations as well as for PGE2 and progesterone concentrations in uterine tissues (r=0.70 and r=0.60, respectively). The results show that the increase in PGE2 concentrations in uterine tissues coincides with the high uterine progesterone concentrations during luteal phase.

Journal Article↗

PubMed1994

Proteolytic activation of hepatocyte growth factor in response to tissue injury.

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes and renal tubular epithelial cells and may play an important role in regeneration following hepatic and renal injury. HGF is first synthesized as a single chain precursor which is then converted to a heterodimeric form by proteolytic processing. This proteolytic conversion is required for HGF to function as a mitogen. In this study, we examined whether the proteolytic activation of HGF occurred in response to hepatic and renal injury. HGF remained as an inactive single chain form in the liver, kidney, lung, and spleen of normal rats. The production of HGF markedly increased in the liver after hepatotoxin treatment and in the kidney after nephrotoxin treatment. A significant portion of the increased HGF was converted to the active heterodimeric form, whereas in other tissues, conversion did not occur although the production of HGF increased in some of them. Furthermore, an enzymatic activity that converts the single chain form of HGF to the active heterodimeric form was detected in the injured liver but not in the normal liver. These results indicate that HGF is proteolytically activated in response to tissue injury, and this activation is mediated by an enzymatic activity which is induced exclusively in the injured tissues. Thus, the proteolytic activation system functions in vivo as a mechanism for localizing HGF activities to injured tissues.

Animals↗

PubMed1994

Ligand-dependent polyubiquitination of c-kit gene product: a possible mechanism of receptor down modulation in M07e cells.

Quantities of proteins in cells are balanced by protein synthesis and degradation. Protein ubiquitination is an important adenosine-triphosphate dependent proteolytic pathway for "short-lived" proteins. We show that soluble steel-factor (SLF) stimulation at 37 degrees C rapidly induced polyubiquitination of c-kit protein in growth-factor-dependent human-myeloid cell line M07e, resulting in smeared, retarded migration of c-kit protein in sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the molecular weight region of 145 kD. Receptor ubiquitination was almost completely absent when cells were treated with SLF at 4 degrees C or at 37 degrees C in the presence of 0.2% sodium azide, or when the cells were pretreated with anti-c-kit monoclonal antibody or genistein, a tyrosine-kinase inhibitor. This suggested that c-kit ubiquitination was ligand dependent and appeared to require intrinsic tyrosine-kinase activation of the c-kit protein. Flow-cytometric analysis of c-kit expression on the cell surface of M07e cells showed down modulation of c-kit within 5 minutes after soluble-SLF treatment at 37 degrees C. However, rapid receptor down modulation was almost completely suppressed when cells were treated with SLF at 4 degrees C or at 37 degrees C in the presence of 0.2% sodium azide, conditions that concomitantly suppressed polyubiquitination of c-kit protein. In addition, these conditions almost completely suppressed radiolabeled SLF (125I-SLF) internalization after ligand-receptor interaction. Pulse-chase studies of 35S-methionine-labeled c-kit protein showed that SLF stimulation at 37 degrees C strikingly enhanced c-kit degradation (T1/2; approximately 20 minutes) compared with that in cells stimulated with SLF at 4 degrees C or at 37 degrees C with 0.2% sodium azide. However, in the presence of chloroquine, which blocks lysosomal degradation, this ligand-induced c-kit degradation at 37 degrees C was only suppressed in part. These data suggest that SLF-induced polyubiquitination of the c-kit receptor protein may play a role in regulation of c-kit-encoded protein-receptor expression in M07e cells.

Amino Acid Sequence↗

PubMed1994

Physical characteristics and polymerization during iron saturation of lactoferrin, a myelopoietic regulatory molecule with suppressor activity.

Lactoferrin (LF) has been implicated in normal regulation of myeloid blood cell production in vitro and in vivo and abnormalities in LF-cell interactions have been associated with progression of leukemia and other hematopoietic disorders. LF may be clinically useful and for this reason we studied selected biochemical characteristics of LF. Purified human milk LF was saturated with iron from solution and analyzed by gel electrophoresis, ion-exchange and gel filtration chromatography. The metalloprotein was found to contain several molecular weight species on polyacrylamide gels. High resolution ion-exchange chromatography demonstrated the binding of LF to both anionic and cationic media under identical conditions indicating a bipolar charge distribution. Gel filtration studies revealed a tetramerized form of LF, the formation and stability of which was dependent on the ionic strength of the solution.

Buffers↗

PubMed1994

Idiopathic peripheral neuropathy in a horse with knuckling.

We report the pathological findings of the skeletal muscle and peripheral nerves from a male 14-months-old thoroughbred horse showing idiopathic knuckling. The affected animal, when in staining position, presented knuckling at the fetlock joint of both forelegs, and dragged both fore- and hindlegs when attempting forward movement. The skeletal muscles demonstrated neurogenic atrophy characterized by the scattering of single angular fibers, groups consisting of five to ten angular fibers, and multiple fascicles of atrophic and hypertrophic fibers. The severity of changes tended to be a distal gradient. While there was no evidence of fiber loss on light microscopy, a diffuse scattering of myelin ovoid, Wallerian-like degeneration and onion-bulb formations were observed in almost all peripheral nerves collected. The characteristic features in electron microscope were swollen axons, which contained accumulations of organelles, especially degenerative mitochondria and neurofilamanets. Onion-bulb formations were frequently found and were associated with Schwann cell processes and occasional collagen pockets. Other prominent feature were Büngner bands which contained myelin debris and regenerating axons or sprouts. These findings suggested that the nature of this disease was a disturbance in axonal transport and were indicative of a distal axonopathy.

Animals↗

PubMed1994

Isolation and partial characterization of crystal matrix protein as a potent inhibitor of calcium oxalate crystal aggregation: evidence of activation peptide of human prothrombin.

In order to clarify the characteristics of crystal matrix protein (CMP), which exhibits a remarkable affinity for calcium oxalate crystals and may be important in stone pathogenesis, we have isolated CMP from macromolecular matrix substances of newly-formed calcium oxalate crystals. Purification of CMP consisted of calcium oxalate crystal formation, dissolution of crystals, electrodialysis, anion exchange chromatography and high-performance liquid chromatography. CMP showed the protein band of 31 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequence of CMP was identical to that of human prothrombin. Both anti-CMP polyclonal antibody and anti-human prothrombin antibody cross-reacted well with human prothrombin and CMP in Western blotting. Its amino acid composition and its molecular weight of 31 kDa strongly suggest that CMP is the activation peptide of human prothrombin.

Adult↗

PubMed1994

Serum gastrin levels following administration of omeprazole alone or in combination with pirenzepine.

Serum gastrin levels in 44 peptic ulcer patients (26 gastric ulcer patients and 18 duodenal ulcer patients) were determined after they had been treated with omeprazole (OPZ) (20 mg/day) alone or in combination with pirenzepine (PZP) (100 mg/day). Serum gastrin levels were measured before, as well as 2, 4, and 6 weeks after administration, and the changes were compared. The levels were significantly elevated (twofold) at 2 weeks of treatment in both the OPZ and OPZ plus PZP groups. In patients taking OPZ alone, the levels rose up to 6 weeks, while in those taking OPZ plus PZP the levels decreased at 4 and 6 weeks. At 4 weeks, serum gastrin levels in the OPZ plus PZP group were lower (although not significantly) than those in patients taking OPZ alone. In gastric ulcer patients, serum gastrin levels in the OPZ group were significantly elevated, while in the OPZ plus PZP group, these levels were only slightly, but not significantly elevated. There was no significant difference between the two gastric ulcer groups at any time. In duodenal ulcer patients, serum gastrin levels increased significantly at 2 weeks of treatment in both groups. At 4 weeks and thereafter, the serum gastrin levels remained significantly high in patients taking OPZ alone, while they decreased at both 4 and 6 weeks in patients taking OPZ plus PZP. Thus, serum gastrin levels in duodenal ulcer patients were markedly decreased by the addition of PZP.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Therapy, Combination↗

PubMed1994

Poisoning by the red alga 'ogonori' (Gracilaria verrucosa) on the Nojima Coast, Yokohama, Kanagawa Prefecture, Japan.

A food poisoning case due to the ingestion of 'ogonori', an edible red alga, occurred at Yokohama, Kanagawa Prefecture, Japan, in late October 1993, resulting in two victims, including one death (female). No causative agent present in the ogonori was found from a routine bioassay for marine toxins. From the production of increased amounts of prostaglandins (PGs), mainly PGE2, by the alga on stimulation by cutting or soaking in fresh water, and further increase of PGE2 by addition of arachidonic acid, it appeared that an enzyme, probably fatty acid cyclooxygenase, in the ogonori and the body of the victim, was acting on the highly unsaturated fatty acids in the oil of the ingested seafood and in the blood hemorrhaged from the stomach of the victim. This resulted in the production of over 30 mg of PGE2 and small amounts of other PGs in a comparatively short time. With this dosage the victim suffered from nausea, vomiting, and hypotension, and died of hypotensive shock. PGE2 seems to work more selectively on females. This type of poisoning is very unusual, and differs from the more familiar forms of poisoning occurring after ingestion of marine organisms.

Animals↗

PubMed1994

Construction of aminotransferase chimeras and analysis of their substrate specificity.

Escherichia coli aspartate aminotransferase (AspAT) and E. coli aromatic amino acid aminotransferase (AroAT) have almost identical and high activities toward acidic amino acid substrates. AroAT also has high activity toward aromatic amino acid substrates. The two proteins have 44% amino acid sequence homology. In order to study the mechanism responsible for the different substrate specificities of these aminotransferases, chimeric enzymes of AspAT and AroAT were constructed using homologous recombination in E. coli cells. Five chimeric enzymes were obtained, even though the nucleotide sequence homology between the two parent enzymes was as low as about 50%. The yields of the legitimate chimeric genes were related to the lengths of the homologous region between the two parent genes. Homologous recombination occurred in the region where more than eight nucleotides out of ten were identical. The substrate specificity of the chimeric enzymes suggest that not only the amino acid residues in the active site but also those distant from the active site contribute to the substrate specificity of the parental aminotransferases.

Amino Acid Sequence↗

PubMed1994

Tyrosine phosphorylation of beta-catenin and plakoglobin enhanced by hepatocyte growth factor and epidermal growth factor in human carcinoma cells.

The effect of hepatocyte growth factor/scatter factor (HGF/SF) and epidermal growth factor (EGF) on cadherin-mediated adhesion of human carcinoma cells was studied. HGF/SF induced scattering of colonic adenocarcinoma HT29 and gastric adenocarcinomas MKN7 and MKN74 cells. Likewise, EGF induced scattering of HT29 and MKN7 cells. These cells expressed E-cadherin, which was concentrated at cell-cell contact sites. When the scattering of these cells was induced by HGF/SF or EGF, the E-cadherin concentration at cell-cell boundaries tended to decrease. Immunoblotting analyses, however, demonstrated that these growth factor treatments did not alter the expression of E-cadherin and E-cadherin-associated proteins, alpha- and beta-catenin and plakoglobin. beta-Catenin, plakoglobin and an unidentified 115-kDa molecule associated with E-cadherin were found to be phosphorylated at tyrosine residues, and these phosphorylations were enhanced by the growth factor treatments. These results suggest that HGF/SF and EGF may modulate the function of the cadherin-catenin system via tyrosine phosphorylation of cadherin-associated proteins.

Cadherins↗

PubMed1994

Percentages of bone marrow blasts and chromosomal changes in patients with refractory anemia help to determine prognoses.

We statistically analyzed the hematologic findings of patients with refractory anemia (RA) to identify parameters associated with a poor prognosis. We first separated the RA patients into two groups: one group with disease progression and one without. The patients with disease progression were predominantly male and had a significantly higher percentage of bone marrow (BM) blasts at the time of diagnosis (3.06 +/- 1.29% vs. 1.44 +/- 1.38%, P < 0.005). This finding was confirmed when the patients were separated into the two groups; those who survived and those who expired (BM blasts: 2.68 +/- 1.59% vs. 1.37 +/- 1.27%, P < 0.005). The survival probabilities were calculated depending on whether or not the RA patients had > or = 3% BM blasts. The RA patients with > or = 3% BM blasts had a significantly worse prognosis (P < 0.01) than the patients with < 3% BM blasts. Notably, the RA patients with > or = 3% BM blasts did not show any significant differences in the incidence of disease progression, mortality rate, or survival probability, when compared with the patients with RA with an excess of blasts (RAEB). The present findings indicate that RA patients are heterogeneous with regard to prognosis, and the RA patients with > or = 3% BM blasts might have a poorer prognosis than those with fewer BM blasts. Thus we propose a general approach in predicting the prognosis of RA patients: those with complex chromosomal changes will expire shortly. Secondly, when the patients do not have any complex changes, the prognosis might be linked to the percentage of BM-blasts at the MDS diagnosis.

Anemia, Refractory↗

PubMed1994

Cardiac effects of the novel pyridazinone derivative 6-[4-[2-[3-(5-chloro-2-cyanophenoxy)-2-hydroxypropylamino]- 2- methylpropylamino]phenyl]-4,5-dihydro-5-methyl-3(2H) pyridazinone monoethyl maleate and its metabolite in isolated heart preparations of guinea pigs and dogs.

The cardiovascular effects of 6-[4-[2-[3-(5-chloro-2-cyanophenoxy)-2- hydroxypropylamino]-2-methylpropylamino]phenyl]-4,5-dihydro- 5-methyl-3(2H) pyridazinone monoethyl maleate (salt) (TZC-5665, CAS 114856-47-2) and its main metabolite in human, M-2, were investigated in isolated atrial and ventricular muscles of guinea pigs and dogs, in guinea pig atrial and right ventricular papillary muscles. TZC-5665 showed negative chronotropic and inotropic effects, whereas M-2 showed a potent positive inotropic effect with a slight positive chronotropic effect. The positive inotropic effect of M-2 was not modified by phentolamine, propranolol and cimetidine, but completely depressed by carbachol. In blood-perfused dog heart preparations, M-2 increased the contractile force and coronary blood flow of paced papillary muscles and sinus rate. Although TZC-5665 scarcely affected the contractile force and sinus rate, it increased coronary blood flow. TZC-5665 scarcely affected atrio-ventricular (AV) conduction time, whereas M-2 slightly shortened AV conduction time. The rate of ventricular automaticity was slightly increased by M-2, but suppressed by TZC-5665 at higher doses. TZC-5665 showed a non-selective beta-adrenoceptor blocking activity comparable to that of propranolol in guinea-pig atrial and tracheal preparations. In enzyme preparations, TZC-5665 and M-2 were more potent and selective inhibitors of phosphodiesterase (PDE) III than milrinone. Combination of beta-adrenoceptor blocking effect of TZC-5665 and positive inotropic effect of M-2 could be useful in the treatment of congestive heart failure by mutual prevention of undesirable effects.

Adrenergic beta-Antagonists↗

PubMed1994

[The clinical significance of glycosylated ferritin in iron overloads and hematopoietic malignancies].

Serum ferritin concentration had been known to represent the amount of total body iron and has been clinically used as a parameter to evaluate the iron storage pool in a whole body. Glycosylated (secreted) and non-glycosylated (non-secreted) forms of serum ferritin (sFt) have been reported by others based on the difference in their affinity to concanavalin-A binding. In this report, we assessed the amount of glycosylated serum ferritin (Glyco-sFt) and the ratio (%) of Glyco-sFt/in hematopoietic disorders including iron overloads (n = 10), leukemias (n = 36), malignant lymphomas (n = 10), multiple myelomas (n = 3) and myelodysplastic syndromes (n = 12). A high percentage of Glyco-sFt was observed in normal healthy controls (n = 18, 78.1 +/- 7.4%) and iron-overloads (61.1 +/- 17.8%) as compared with that in hematopoietic malignancies (43.8 +/- 23.4%, p < 0.001). The amount of Glyco-sFt in iron-overloads was higher than that in hematopoietic malignancies with hyperferritinemia (p < 0.005). These data demonstrated that the same part of serum ferritin in hematopoietic malignancies was the non-secreted form and appeared to be derived from tumor cell lysis. We conclude that assessment of Glyco-Ft is a useful parameter to distinguish iron-overloads from malignant hematopoietic disorders both displaying hyperferritinemia.

Concanavalin A↗

PubMed1994

Effect of beta-lactamase on minimum inhibitory concentrations of methicillin in methicillin-resistant Staphylococcus aureus.

A study was undertaken to determine whether the production of penicillin-binding protein-2' (PBP-2') and the production of beta-lactamase were related to the minimum inhibitory concentrations of methicillin (DMPPC) in various strains of methicillin-resistant Staphylococcus aureus. The amount of PBP-2' produced by the low-level resistant strain L20A was small and the strain became resistant to DMPPC as a result of inactivation of DMPPC by beta-lactamase. The largest amount of PBP-2' produced was in a moderately resistant strain L21A but the MIC was not high since the strain was not capable of producing beta-lactamase and the population of cells was heterogeneous. The amount of PBP-2' produced in the high-level resistant strain L457A was lower than that in strain L21A but the MIC was high as a result of the production of beta-lactamase. Production of PBP-2' was essential for resistance to methicillin but production of beta-lactamase had a major effect on the MIC.

Bacterial Proteins↗

PubMed1994

[Studies on the modified dimethylmethylene-blue (DMB) method for determining glycosaminoglycans (GAG) in urine].

The measurement of glycosaminoglycans (GAG) in urine is very important because GAG is an essential constituent of urinary diseases. Since previously reported methods of determination of GAG are quite complicated, dangerous or not stable, we developed a very simple and rapid method to estimate the content of GAG in urine using a microplate and microplate reader. An aliquot of diluted urine is mixed with a 1,9, dimethylmethylene blue (DMB) dye. The assay is based on the metachromatic shift in absorption maximum which occurs when sulfated glycosaminoglycans are added to the dye. The recovery of GAG is good. Other urinary compounds such as sugar, protein and blood did not influence the measurement of GAG. A good correlation was obtained between the modified DMB method and Blumenkrantz and Asboe-Hansen's method (r = 0.737, p < 0.001). The accuracy of this method makes it useful for screening urinary diseases.

Adult↗

PubMed1994

Potential molecules implicated in downstream signaling pathways of p185BCR-ABL in Ph+ ALL involve GTPase-activating protein, phospholipase C-gamma 1, and phosphatidylinositol 3'-kinase.

Constitutive activation of BCR-ABL tyrosine kinase fusion protein has been shown to be an essential step in the pathogenesis of Philadelphia chromosome (Ph)-positive leukemias. We studied the tyrosine phosphorylated proteins which might be involved in the signaling pathway p185BCR-ABL using a Ph-positive acute lymphoblastic leukemia cell line. p185BCR-ABL but not p145c-abl was constitutively phosphorylated on tyrosine in this cell line. p21ras GTPase-activating protein (GAP) was physically associated with p185BCR-ABL, but not with p145c-abl, and GAP-associated proteins p62/p190 were found to be tyrosine-phosphorylated. Furthermore, p185BCR-ABL was also physically associated with phospholipase C-gamma 1 (PLC-gamma) and phosphatidylinositol 3'-kinase (P13-kinase). Concomitantly, both PLC-gamma and p85 subunit of P13-kinase are tyrosine-phosphorylated in the cells with p185BCR-ABL. These data suggest that GAP, GAP-associated proteins, PLC-gamma, and P13-kinase may participate in downstream signaling for p185BCR-ABL tyrosine kinase.

Animals↗

PubMed1993

Stimulation of prostaglandin production by hepatocyte growth factor in human gastric carcinoma cells.

Hepatocyte growth factor (HGF), a protein with pleiotropic biological activity affecting cell growth and motility, was found to markedly activate prostaglandin production in human gastric carcinoma TMK-1 cells. HPLC analysis revealed that HGF stimulated the production of prostaglandin E2 (PGE2), which is the major prostaglandin produced in these cells. HGF maximally stimulated PGE2 production at a concentration of 10 ng/ml, and it was a more potent stimulator of PGE2 production than epidermal growth factor (EGF), which is known to stimulate prostaglandin production in various cell lines. The simultaneous addition of HGF and EGF caused no further stimulation of the PGE2 production observed in HGF-treated cells. We showed also that HGF increased the arachidonate release from TMK-1 cells, which release was completely suppressed by the addition of phospholipase A2 (PLA2) inhibitors. Further studies in vitro showed that HGF enhanced cellular activities of cytosolic PLA2 and cyclooxygenase 1.5-fold each. These results indicate that HGF stimulates prostaglandin production through increases in both cytosolic PLA2 and cyclooxygenase activities.

Chromatography, High Pressure Liquid↗