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Biomedical subjects

H Miyata

Publications and source records attributed to H Miyata.

At least 235 records · Page 13Linked to original sources
PubMed1995

[Pharyngeal metastasis and arteriovenous fistula of renal cell carcinoma--report of a case].

A 76-year-old Japanese male consulted our hospital complaining of dysphagia. He also complained of dyspnea, and a cardiovascular disorder was detected. Otolaryngological examination revealed dysphagia due to pharyngeal tumor. Further examination detected left renal cell carcinoma with multiple pulmonary metastasis, and selective angiography revealed arteriovenous fistula in the primary tumor. After resection of the pharyngeal tumor and left nephrectomy, pharyngeal tumor was pathologically confirmed as metastasis of renal cell carcinoma. Furthermore, after left nephrectomy, the cardiovascular disorder gradually improved. Thus, the cardiovascular disorder was considered to have developed based upon the arteriovenous fistulae. Pharyngeal metastasis of renal cell carcinoma is extremely rare, and the cardiovascular disorder in this case was also an extrarenal manifestation.

Aged↗
PubMed1995

[Exposure to blood during midwifery operations--a questionnaire study].

A self-administered questionnaire was mailed to all midwives working in Nara Prefecture to investigate blood exposure events at delivery and to consider protective measures for the exposure. Out of the 203 midwives 193 responded to the questionnaire. The median number of deliveries in which the midwives had assisted within the past one year was 35 after excluding those who had not assisted in deliveries at all. The incidence of needle-stick injuries was estimated to be 86.2 per 100 persons within the past one year. The occurrence in the subgroup who had worked as midwife for less than 5 years was 2-3 times higher than that in those who worked for more than 5 years. Over 90% of the midwives had experiences of direct blood contact events to the skin while assisting in their 10 most recent deliveries. Blood contact events occurred in the finger-hand-arm area in 85% of the midwives, on the legs in 62%, in the face in 20% and in the eyes in 1%. Around 20% of the midwives had unintentionally sucked amniotic fluid when using a tracheal catheter on a newborn. The most common occasion where direct blood contact events occurred was while bathing an infant for removing blood and amniotic fluid. The midwives wore a disposal gown more often when assisting in labors of parturient women infected with blood-born infectious diseases than without the diseases, and similarly for wearing gloves when measuring blood loss and for usage of a mechanical device for sucking amniotic fluid in the tracheae of an infant. Based on the results obtained in this questionnaire study and our previous study about blood contact events observed in a delivery room, protective measures for midwives against exposure to blood at delivery are required and some ideas are presented.

Accidents, Occupational↗
PubMed1995

[The involvement of protein kinase C isozymes in activation of phospholipase D and secretion of serotonin in rat basophilic leukemia cells].

Western blot analysis shows the presence of protein kinase C (PKC) alpha, beta1, beta2, delta, epsilon, zeta isozymes in rat basophilic leukemia (RBL-2H3) cells. Antigen stimulation caused preferential translocation of protein kinase C (PKC) delta and epsilon to membranes. On the other hand, when the cells were stimulated by phorbol 12-myristate 13-acetate (PMA) or ionophore (A23187), PKCalpha and beta were predominantly translocated. Phospholipase D (PLD) was activated by three stimulants in order: A23187 > PMA >> antigen. Therefore, PKCalpha and beta seem to be involved in the activation of PLD in RBL cells. The translocation of all PKC isozymes in A23187 stimulation was weak. Therefore, PLD activation in A23187 stimulation may require some other factors than PKC which are associated with the increase of Ca2+ in the cells. The cells stimulated by antigen secreted serotonin to the same level as the cells stimulated by A23187. In both stimulation, PKCalpha and epsilon were translocated to almost similar level, suggesting that PKCalpha and epsilon are involved in the secretion. All PKC isozymes except zeta were markedly translocated in PMA stimulation, but secretion did not occur. These results indicate that translocation of PKC alpha and beta may be associated with PLD activation and also that both translocation of PKCalpha and epsilon and intracellular calcium increase are required for serotonin secretion in RBL cells.

Animals↗
PubMed1994

Potent activation of phospholipase D by phenylarsine oxide in rat basophilic leukemia (RBL-2H3) cells.

A putative protein tyrosine phosphatase inhibitor, phenylarsine oxide (PAO), potentiated phospholipase D (PLD) activity concentration-dependently in [3H] oleic acid-labeled rat basophilic leukemia (RBL-2H3) cells without significant increase in phosphatidylinositol-specific phospholipase C (PI-PLC) activity. Although PAO induced tyrosine phosphorylation of several proteins, both PAO-induced PLD activation and tyrosine phosphorylation were not affected by a protein tyrosine kinase inhibitor, genistein. Another tyrosine kinase inhibitor, herbimycin A, prevented the PAO-induced PLD stimulation but had no effect on protein tyrosine phosphorylation. However, depletion of protein kinase C (PKC) greatly reduced PAO-stimulated PLD activity. These results indicate that PKC but not tyrosine kinase may be involved in PAO-mediated PLD activation.

Animals↗
PubMed1994

Antigenic phenotypes of Escherichia coli in urine from patients with urinary tract infections.

Various antigenic phenotypes of Escherichia coli in urine were analysed using monoclonal antibody against pyelonephritis-associated P-pili (PAP-pili), and polyvalent O- and K1-antisera, and the results were compared with the clinical diagnosis. PAP-pili, O1- and K1-positive E. coli were isolated more frequently in urine from patients with acute pyelonephritis. E. coli found in urine from patients with recurrent pyelonephritis were frequently PAP positive. Based on the antigenic phenotypes of strains in urine, it is suggested that pyelonephritopathogenic strains may originate from a small number of clones.

Acute Disease↗
PubMed1994

Production and characterisation of monoclonal antibodies against pyelonephritis-associated P-pili of Escherichia coli.

Pyelonephritis-associated P-pili (PAP) of Escherichia coli O6,H(-),K1(-),F12,haemolysin(-) were purified by salt precipitation and affinity chromatography using Synsorb P1. Purified PAP showed a single band with a molecular weight of 18 kDa by electrophoretic analysis. A monoclonal antibody (mAb) was produced by fusion of the PAI myeloma cell line with splenic lymphocytes from BALB/c mice immunised with the purified PAP. The mAb was of IgM class with kappa light chains and reacted with a 18-kDa moeity of the salt precipitate; the epitope was present near the apical part of the pilus filaments. The mAb reacted with PAP in both immunofluorescence and haemagglutination tests when 108 strains isolated from urine samples were tested; the two tests were in agreement for 202 of 204 strains isolated from faecal samples.

Animals↗
PubMed1994

Phosphoinositide hydrolysis in Ki-ras-transformed fibroblasts stimulated by platelet-derived growth factor and bradykinin.

Signal transduction in response to platelet-derived growth factor (PDGF)-BB and bradykinin (BK) have been examined by measuring inositol polyphosphate formation in NIH3T3 fibroblast and v-Ki-ras-transformed NIH3T3 fibroblast (DT). The PDGF-induced inositol polyphosphate formation in NIH3T3 was greater than that in DT cells, in which autophosphorylation of PDGF receptor and tyrosine phosphorylation of phospholipase C (PLC)-gamma 1 were suppressed when examined by immunoblotting with anti-phosphotyrosine antibody. On the other hand, BK-stimulation produced a much higher level of inositol polyphosphate in DT cells which have a greater number of BK receptors. These results indicate that in Ki-ras transformed cells the decrease (caused by PDGF) and the increase (caused by BK) in phosphoinositide hydrolysis are due to the defective autophosphorylation of PDGF receptors leading to a reduction in PLC-gamma 1 tyrosine phosphorylation and the overexpression of BK receptors, respectively.

3T3 Cells↗
PubMed1994

Inhibition by tranilast of collagen accumulation in hypersensitive granulomatous inflammation in vivo and of morphological changes and functions of fibroblasts in vitro.

We examined the effects of tranilast, an anti-allergic agent, on hypersensitive inflammation and on morphology and functions of fibroblasts. In vivo, tranilast suppressed the content of collagen in granulation tissue of hypersensitive granulomatous inflammation induced by methylated bovine serum albumin (m-BSA) in rats. In culture, tranilast inhibited the TGF-beta-independent inflammatory exudate-induced stimulation of morphological changes of fibroblasts to myofibroblast-like cells and their proliferation. Collagen gel contraction by myofibroblast-like cells and fibroblasts was also inhibited by tranilast. Flow cytometric analysis revealed that tranilast suspended the cell cycle of fibroblasts at the G0/G1 phase. These results suggest that tranilast modulates the fibrosis and contraction of granulation tissue by inhibiting the growth of myofibroblast-like cells and fibroblasts.

Administration, Oral↗
PubMed1994

Fluorescence imaging of intracellular Ca2+.

The measurement of intracellular Ca2+ concentrations ([Ca2+]i) is of critical importance, because many cellular functions are tightly regulated by [Ca2+]i. The fluorescent indicator, fura-2, has been used frequently to measure [Ca2+]i because of its sensitivity and specificity, and because it can be loaded into living cells with little disruption of function. Most importantly, the peak excitation wavelength of fura-2 changes when it binds Ca2+. As a consequence, measurements of fluorescence at two excitation wavelengths can be used to obtain an estimate of [Ca2+]i that is independent of dye concentration and cell thickness. Fura-2 acetoxymethyl ester (AM) is a lipid-soluble derivative that is often used because of its ability to pass through cell membranes. There are, however, several problems with the use of fura-2 AM such as intracellular compartmentation and incomplete deesterification. The availability of low-light-level cameras and computer hardware for the digitization of fluorescent images has made quantitative fluorescence microscopy possible. This technique has shown a striking spatial heterogeneity of [Ca2+]i in a variety of cell types, and has revealed substantial new information on dynamic intracellular biochemistry and signal transduction. However, the current imaging technology is not fully developed because of dye and instrumentation limitations. Further development of techniques and new probes are required to improve temporal and spatial resolution.

Animals↗
PubMed1994

Transformation of actin-encapsulating liposomes induced by cytochalasin D.

Liposomes encapsulating actin filaments were prepared by swelling at 0 degrees C lipid film consisting of a mixture of dimyristoyl phosphatidylcholine and cardiolipin (equal amounts by weight) in 100 microM rabbit skeletal muscle actin and 0.5 mM CaCl2 followed by polymerization of actin at 30 degrees C. Liposomes initially assumed either disk or dumbbell shape, but when cytochalasin D was added to the medium surrounding the liposomes, they were found to become spindle shaped. Liposomes containing bovine serum albumin that were given cytochalasin D and actin-containing liposomes that were given dimethylformamide, the solvent for cytochalasin D, did not transform. These results indicated actin-cytochalasin interaction is involved in the transformation process. Falling-ball viscometry and sedimentation analysis of actin solution indicated that cytochalasin cleaved actin filaments and caused depolymerization. The observation of polarized fluorescence of encapsulated actin labeled with acrylodan indicated that the actin filaments in the transformed liposomes aligned along the long axis of the liposomes. Because the actin filaments in the disk- or dumbbell-shaped liposomes formed bundles running along the liposome contour, the transformation was likely to be accompanied by the change in the actin filament arrangement in the liposomes, which was induced by actin-cytochalasin interaction.

Actins↗
PubMed1994

Ultracytochemistry of glycoconjugates in pig duodenal gland.

To elucidate the ultrastructure, glycoprotein profile and site of glycosylation of glandular cells in relation to the functional polarity of the organelles, swine duodenal tissue was embedded in glycol methacrylate and subsequently stained for periodic acid thiocarbohydrazide silver proteinate (PA-TCH-SP), high iron diamine (HID)-TCH-SP, low iron diamine (LID)-TCH-SP, ninhydrin T-TCH-SP and five peroxidase-labeled lectins. The secretory granules in the duodenal gland cells were electron lucent with a 200 nm to 500 nm electrondense core. Glycoconjugates were confined to the secretory granules and elements of the Golgi complex. Protein activity was located only in the electron dense core. Achivementestic staining pattern for Concanavalin A (Con A), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) was observed in stained secretory granules and the Golgi apparatus. A few cis cisternae were stained with SBA and UEA-I. Trans cisternae were stained with WGA and PNA. Con A reacted with seromucous granules and rough endoplasmic reticulum. These observational findings suggest that these are seromucous cells. The Golgi apparatus is the site of glycosylation and can be divided into two distinct compartments.

Animals↗
PubMed1994

Stepwise motion of an actin filament over a small number of heavy meromyosin molecules is revealed in an in vitro motility assay.

In order to determine the relative motions of an actin filament and a myosin molecule upon hydrolysis of one ATP, an in vitro motility assay, in which individual actin filaments slide over heavy meromyosin molecules bound to a substrate, was combined with an optical trapping technique. An actin filament, attached to a gelsolin-coated bead, was captured with an optical trap. The surface-bound heavy meromyosin molecules pulled the filament against the trapping force, which resulted in back and forth motions of the actin-bound bead. The number of heavy meromyosin molecules interacting with an actin filament (at most 1/micron filament) and the ATP concentration (< or = 0.5 microM) were chosen so as to facilitate detection of each "pull." Calculation of the centroid of the bead image revealed abrupt displacements of the actin filament. The frequency of such displacements was between 0.05 and 0.1 per 1 s per 1 micron actin filament, being consistent with calculated values based on the reported bimolecular binding constants of ATP and the actomyosin rigor complex. The distribution of the displacements peaked around 7 nm at a trapping force of 0.016 pN/nm, but it became broader, and some displacements were as large as 30 nm, when the trapping force was reduced to 0.0063 pN/nm, suggesting that the force generation due to the structural change of a myosin head may be insufficient to explain such displacements.

Actins↗
PubMed1994

Transient erythroblastopenia due to human parvovirus B19 infection: a case report of a boy suffering from purpura.

Transient erythroblastopenia of childhood (TEC) was observed in a boy infected by human parvovirus B19 (B19) before the manifestation of the typical clinical picture of erythema infectiosum (EI). He did not have any apparent symptoms of anemia, and spontaneous resolution of erythroblastopenia was observed before the manifestation of the symptoms of EI. The difference between primary B19 infection and classical TEC is discussed.

Child↗
PubMed1994

Regulation of intracellular free Mg2+ and contraction in single adult mammalian cardiac myocytes.

Studies in isolated cardiac myocytes have increased our understanding of intracellular Ca2+ regulation. Because less is known about Mg2+ regulation, adult rat ventricular myocytes were loaded with the Mg(2+)-sensitive fluorescent probe mag-indo 1, and changes in intracellular Mg2+ concentration ([Mg2+]i) and cell length were examined under a variety of conditions. The fluorescent signal was calibrated intracellularly and found to differ slightly from that for the probe in solution. Roughly 40% of the signal was intramitochondrial; the remainder was localized in the cytosol. Basal [Mg2+]i averaged 1.02 +/- 0.03 mM (n = 53 cells). No change in [Mg2+]i was observed during a single electrically stimulated contraction, and only a minor increase was seen during rapid electrical stimulation, which was expected to raise intracellular Ca2+ concentration ([Ca2+]i) to approximately 1 microM. An acid shift in intracellular pH of approximately 1 pH unit was accompanied by a small change in [Mg2+]i (0.34 +/- 0.03 mM, n = 6, P < 0.05). No change in [Mg2+]i was observed when cells were superfused with 15 mM Mg2+, despite marked changes in contraction. [Mg2+]i more than doubled when cells were depleted of ATP by exposure to hypoxia or metabolic inhibitors. The increase in [Mg2+]i was abrupt and occurred at the time of the failure of contraction, plateauing as rigor contracture developed. Reoxygenation was accompanied by a gradual fall in [Mg2+]i in cells that recovered mechanical function, and in a subset of cells that underwent hypercontracture. Studies in cell suspensions confirmed that rapid cellular energy depletion was accompanied by increases in [Mg2+]i and parallel decreases in ATP. Thus [Mg2+]i was largely insensitive to changes in [Ca2+]i or pHi and extracellular [Mg2+] but was rapidly altered by changes in energy state in a manner that was related to specific changes in cell morphology and contractile function.

Adenosine Triphosphate↗