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M Tamura

Publications and source records attributed to M Tamura.

At least 757 records · Page 42Linked to original sources
PubMed1989

Immunohistochemical study of cellular response on the intraocular lens surface.

This immunohistochemical study was conducted to observe the cellular proliferation on the surface of an intraocular lens (IOL) implanted in the rabbit eye. One week after extracapsular lens extraction followed by posterior chamber lens implantation, the IOL was removed and examined by an indirect immunohistochemical method using anti-macrophage antiserum. Macrophage immunoreactivities were observed on the small round cells, the middle-sized oval cells, the foreign-body giant cells and the fibroblast-like cells attached to the surface of the IOL. Most of the cellular components on the implanted IOL seemed to be macrophages.

Animals↗
PubMed1989

Intracavernous injection therapy in recovery of spontaneous erection (not for self-injection)--its mechanism and indications.

Ten impotents underwent intracavernous injection therapy for recovery of spontaneous erection using papeverine hydrochloride alone or in combination with phentolamine. Six out of ten patients recovered spontaneous erection. Almost all respondents tended to have low initial penile-brachial-index values and their penile-brachial-index values rose after treatment. We concluded that periodic erections after using a vasoactive drug may have the effect of stimulating and activating the lethargic blood flow system and finally revitalizing the erectile organ.

Adult↗
PubMed1989

[Radiation therapy of adult cerebral glioblastoma:].

For the past twenty years, 85 adult patients with cerebral glioblastoma were treated with postoperative radiation therapy (RT). Hypofractionated RT (5 Gy twice a week) was performed in 31 patients. The survival rate of the hypofractionated RT was superior to the conventionally fractionated RT, especially in the patients involved mainly in the frontal lobe. In the hypofractionation group, misonidazole proved of benefit to the survival. In future, hyperfractionation of RT seems reasonable to be explored for improving CNS tolerance.

Adult↗
PubMed1988

The superoxide-generating respiratory burst oxidase of human neutrophil plasma membrane. Phosphatidylserine as an effector of the activated enzyme.

The superoxide-generating respiratory burst oxidase is an integral membrane enzyme found in the plasma membrane of polymorphonuclear leukocytes (neutrophils). NADPH-dependent superoxide generation is seen in isolated plasma membranes and in their detergent extracts following activation of the intact cells with phorbol myristate acetate. We have herein examined the effects of phospholipids on the activity of the solubilized oxidase. Solubilization of plasma membranes with 0.5% each of Tween 20 plus deoxycholate resulted in an approximately 2-fold enhancement of activity. Inclusion of phospholipids in the extraction medium resulted in further activation. At 1.0 mg/ml the order of effectiveness was phosphatidylserine (PS) greater than cardiolipin greater than phosphatidylethanolamine greater than phosphatidylinositol; phosphatidylcholine and phosphorylated inositol lipids were not effective. The concentrations required for half-maximal activation by PS and phosphatidylethanolamine were 85 and 200 micrograms/ml, respectively. When PS was used at a maximally activating concentration (0.5 mg/ml), the activity was enhanced 3-5-fold. Detergent solubilization alone elevated the Km of the oxidase for NADPH from 68 microM in intact plasma membranes to 123 microM, but inclusion of PS with detergent restored the Km to near or below that seen in intact membranes. PS also increased the Vmax by a factor of 2-3, but had no effect on the pH optimum. A plot of the activity versus enzyme concentration was linear when membranes were used, but activity showed a quadratic dependence on concentration in solubilized membrane, with lower than expected activity at lower enzyme concentration. PS restored linearity of the concentration-activity plot. The activation by PS was not influenced by the addition of Ca2+, EGTA, or dioctanoylglycerol, indicating that activation was not dependent on protein kinase C. These results implicate phosphatidylserine as a direct effector of the NADPH-oxidase.

Cell Membrane↗
PubMed1988

Phorbol myristate acetate (PMA) augments chemoattractant-induced diglyceride generation in human neutrophils but inhibits phosphoinositide hydrolysis. Implications for the mechanism of PMA priming of the respiratory burst.

Pretreatment ("priming") of neutrophils with a non-activating concentration (2 nM) of phorbol myristate acetate (PMA) augments superoxide (O2-) production in response to the chemoattractant formylmethionylleucylphenylalanine (fMLP). We initially examined the effect of sphinganine, an inhibitor of protein kinase C (Ca2+/phospholipid-dependent enzyme), on activation of primed neutrophils. In both primed and unprimed cells activation by fMLP was blocked, and inhibition occurred at identical concentrations, supporting a common inhibited site. PMA also augmented (about 2-fold) fMLP-induced generation of sn-1,2-diglyceride (DG), the level of which correlated with O2- generation. In contrast to its effects on DG, PMA diminished by about 50% the magnitude of the fMLP-stimulated rise in cytosolic Ca2+. Thus, PMA priming dissociates the fMLP-stimulated Ca2+ increase from DG and O2- generation. The effect of PMA on Ca2+ levels appeared to be due in part to lowered levels of inositol trisphosphate. Lowering of inositol phosphate levels correlated with inhibition of fMLP-induced hydrolysis of inositol-containing phospholipids, particularly phosphatidylinositol 4,5-bisphosphate. PMA did not inhibit (and in fact augmented at early time points) formation of [32P] phosphatidic acid in response to fMLP, indicating that the increase in DG was not due to inhibition of cellular diglyceride kinase. Thus, the data suggest that PMA enhances fMLP-stimulated DG generation concomitant with switching the source of DG from phosphatidylinositol 4,5-bisphosphate to an alternative lipid(s). Increased DG and inhibition of activation by sphinganine are consistent with a role for protein kinase C in activation of the respiratory burst in PMA-primed neutrophils.

Diglycerides↗
PubMed1988

A menadione-stimulated pyridine nucleotide oxidase from resting bovine neutrophil membranes. Purification, properties, and immunochemical cross-reactivity with the human neutrophil NADPH oxidase.

A menadione-stimulated, superoxide-generating enzyme was purified 127-fold from resting bovine polymorphonuclear leukocyte (neutrophil) membranes with a yield of 34%. The enzyme was extracted with Triton X-100 and purified by chromatography on DEAE-Sepharose CL-6B, NAD-agarose, and Sephacryl S-200. The purified enzyme contained FAD and had an apparent molecular mass of 93 kDa by sodium dodecyl sulfate gel electrophoresis. In a nondenaturing gel electrophoresis system, the enzyme was multimeric (Mr greater than 400,000). The oxidase showed 3-4-fold higher activity (Vm) with NADH compared with NADPH, but the Km for both pyridine nucleotides was similar (39 and 47 microM, respectively). The enzyme transferred electrons to cytochrome c, dichlorophenolindophenol, and nitro blue tetrazolium. Cytochrome c reduction was stimulated 4-fold by menadione and was inhibited 70% by superoxide dismutase. Cytochrome c reduction was not inhibited by several mitochondrial respiratory chain inhibitors (azide, cyanide, and rotenone) but was sensitive to thiol-reactive agents (p-chloromercuribenzoate and monoiodo acetate). The catalytic properties of this enzyme distinguish it from the NADPH-dependent superoxide-generating respiratory burst oxidase (NADPH-oxidase) of human neutrophils. Nevertheless, antibodies to this enzyme inhibited not only the purified menadione-stimulated oxidase, but also the respiratory burst oxidase in membranes isolated from activated human neutrophils, indicating similar antigenic determinants are shared by these enzymes. Western blots of human neutrophil membranes visualized a plasma membrane protein of molecular mass 67 kDa, corresponding in size to a protein previously reported in preparations of the human respiratory burst oxidase.

Animals↗
PubMed1988

Isolation and characterization of a specific endogenous Na+,K+-ATPase inhibitor from bovine adrenal.

In order to identify a specific endogenous Na+,K+-ATPase inhibitor which could possibly be related to salt-dependent hypertension, we looked for substances in the methanol extract of bovine whole adrenal which show all of the following properties: (i) inhibitory activity for Na+,K+-ATPase; (ii) competitive displacing activity against [3H]ouabain binding to the enzyme; (iii) inhibitory activity for 86Rb uptake into intact human erythrocytes; and (iv) cross-reactivity with sheep anti-digoxin-specific antibody. After stepwise fractionation of the methanol extract of bovine adrenal glands by chromatography on a C18 open column, a 0-15% acetonitrile fraction was fractionated by high-performance liquid chromatography on a Zorbax octadecylsilane column. One of the most active fractions in 0-15% acetonitrile was found to exhibit all of the four types of the activities. It was soluble in water and was distinct from various substances which have been known to inhibit Na+,K+-ATPase such as unsaturated free fatty acids, lysophosphatidylcholines, vanadate, dihydroxyeicosatrienoic acid, dehydroepiandrosterone sulfate, dopamine, lignan, ascorbic acid, etc. This substance was further purified by using an additional five steps of high-performance liquid chromatography with five different types of columns. Molecular mass was estimated as below 350 by fast atom bombardment mass spectroscopy and ultrafiltration. Heat treatment at 250 degrees C for 2 h and acid treatment with 6 N HCl at 115 degrees C for 21 h almost completely destroyed the inhibitory activity of the purified substance for Na+ pump activity. Additionally, alkaline treatment with 0.2 N NaOH at 23 degrees C for 2 h destroyed approximately 70% of the inhibitory activity, whereas boiling for 10 min and various enzyme digestion did not destroy the activity. The dose dependency for the four types of the activities for this substance paralleled those of ouabain, spanning 2 orders of magnitude in concentration range. The inhibitory potencies of the purified substance for Na+,K+-ATPase, Na+ pump, and ouabain binding activities were diminished with increasing K+ concentration, exhibiting a characteristic typical of cardiac glycosides. This substance had no effect on the Ca2+-ATPase activity or the Ca2+ loading rate into the vesicle prepared from skeletal muscle sarcoplasmic reticulum. These results strongly suggest that this water-soluble nonpeptidic Na+,K+-ATPase inhibitor may be a specific endogenous regulator for the ATPase.

Adenosine Triphosphatases↗
PubMed1988

The opposite effect of bivalent cations on cytochrome b5 reduction by NADH:cytochrome b5 reductase and NADPH:cytochrome c reductase.

The effects of bivalent cations on cytochrome b5 reduction by NADH:cytochrome b5 reductase and NADPH:cytochrome c reductase were studied with the proteinase-solubilized enzymes. Cytochrome b5 reduction by NADH:cytochrome b5 reductase was strongly inhibited by CaCl2 or MgCl2. When 1.2 microM-cytochrome b5 was used, the concentrations of CaCl2 and MgCl2 required for 50% inhibition (I50) were 8 and 18 mM respectively. The inhibition was competitive with respect to cytochrome b5. The extent of inhibition by CaCl2 or MgCl2 was much higher than that by KCl or other alkali halides. In contrast, cytochrome b5 reduction by NADPH:cytochrome c reductase was extremely activated by CaCl2 or MgCl2. In the presence of 5 mM-CaCl2, the activity was 24-fold higher than control when 4.4 microM-cytochrome b5 was used. The magnitude of activation by CaCl2 was 2-3-fold higher than that by MgCl2. The activation by these salts was much higher than that by KCl, indicating that bivalent cations play an important role in this activation. The mechanisms of inhibition and activation by bivalent cations of cytochrome b5 reduction by these two microsomal reductases are discussed.

Calcium↗
PubMed1988

QT intervals as an index of high serum calcium in hypercalcemia.

The relationship between QT interval and serum calcium concentration (s-Ca) was examined in 9 hypercalcemic (s-Ca greater than 11 mg/dl) patients. Three QT intervals corrected by Bazett's formula were used for the analysis: the intervals from the beginning of the QRS to the onset (QoTc), the apex (QaTc), and the end of T wave (QeTc). The measurements of s-Ca and other electrolytes were made on the blood sample taken on the same day of the electrocardiogram (ECG) recordings. The normal range of s-Ca and three QTc intervals was determined in 50 outpatients with no cardiac disease. Three QT intervals in the hypercalcemic patients were significantly shortened with a diminution in the s-Ca. The QTc intervals showed significant negative correlation with s-Ca. Sensitivity of QoTc, QaTc, and QeTc in predicting high s-Ca was 83%, 57%, and 39%, respectively, and specificity was 100%, 100%, and 89%. The PQ interval tended to be prolonged in the case of hypercalcemia, but the change was statistically insignificant. These observations suggest that QT intervals can serve as an indicator of high s-Ca and that the QoTc seems to be a good indicator of the three QTc's.

Adult↗
PubMed1988

The simultaneous measurements of tissue oxygen concentration and energy state by near-infrared and nuclear magnetic resonance spectroscopy.

The oxygenation and energy states of brain tissues were measured simultaneously by near-infrared photometry and nuclear magnetic resonance spectroscopy in situ. In both cat and dog, the critical hemoglobin oxygenation was 10%, below which the ratio of phosphocreatine (PCr) to inorganic phosphate (Pi) started to fall. The fall of PCr/Pi paralleled the reduction of copper in cytochrome aa3. The separation of the cytochrome aa3 signal from that of hemoglobin by our optical method was confirmed by the substitution of blood by fluorocarbon solution. The energy-oxygen diagram (PCr/Pi against hemoglobin oxygenation, HbO2) was the same in normal- and fluorocarbon substituted cats, but energy curve shifted to the right in the latter when PCr/Pi plotted against the inspired oxygen, FiO2.

Animals↗
PubMed1988

Development of inactivated vaccine against virus causing haemorrhagic fever with renal syndrome.

B-1 virus belonging to the hantavirus group was serially passaged in the brains of newborn mice. Inactivated vaccine was prepared from the brains after inactivation with formalin and then purification by ultracentrifugation. The antigenic potency of this vaccine in vitro was determined by antibody-bound enzyme-linked immunosorbent assay (ELISA) and serial diluted vaccine bound to an aluminium hydroxide gel was inoculated into Balb/c mice to test immunogenicity. After two injections of this vaccine preparation, antibodies were detected in the mice by immunofluorescent, neutralizing and haemagglutination inhibition antibody tests. When mice immunized with this vaccine were challenged with B-1 virus and Hantaan virus (KHF-83-61BL strain), the virus titres in their lungs and spleens were significantly less than those in non-immunized mice. These results suggest that inactivated B-1 virus vaccine is effective against virus challenge by homotypic (B-1 virus) and heterotypic (Hantaan virus) viruses.

Animals↗
PubMed1988

Piston-pump-type high frequency oscillatory ventilation for neonates with congenital diaphragmatic hernia: a new protocol.

High frequency ventilation and extracorporeal membrane oxygenation (ECMO) are devices that are expected to save the lives of newborn infants whose pulmonary conditions have deteriorated. A piston-pump-type high-frequency oscillator (HFO), developed by Bryan and Miyasaka called "Hummingbird," is considered to be superior to high frequency "jet" ventilators or those of the flow-interrupter type, and was used successfully in two neonates with congenital diaphragmatic hernia (CDH) in a high-risk group. The first baby was on a conventional ventilator with pharmacologic support for the first 54 hours and then operated on. Postoperative deterioration necessitated the use of HFO for the next eight days. The infant then recovered uneventfully. For the second baby, HFO was necessary both preoperatively and postoperatively. This baby had a major diaphragmatic defect and her case was complicated with pneumothorax. There was a long stormy course on HFO (total, 70 days), but the patient was successfully extubated on the 75th day postoperatively and is now doing well. We believe active long preoperative stabilization with pharmacologic support and preoperative and postoperative hyperventilation with a piston-pump-type HFO may be a new innovative strategy for the management of severe CDH patients.

Female↗
PubMed1988

Experimental intraocular lens implantation in the rabbit eye and in the mouse peritoneal space. Part I: Cellular components observed on the implanted lens surface.

Polymethylmethacrylate and silicone intraocular lenses (IOLs) were implanted in the rabbit eye and in the mouse peritoneal space to study cellular response to the implanted IOL. Animals were sacrificed at various times after implantation. The removed IOLs were properly fixed and stained using Wolter's implant cytology technique. Scanning and transmission electron microscopic studies were performed. Macrophages, lymphocytes, and fibroblast-like cells were the major components identified. Occasional formations of foreign-body giant cells were seen. The responses observed on IOLs implanted in the rabbit eye were generally milder than those observed on IOLs implanted in the mouse peritoneal space.

Animals↗
PubMed1988

Experimental intraocular lens implantation in the rabbit eye and in the mouse peritoneal space. Part II: Morphological stages of the macrophage on the implanted lens surface.

Macrophages appearing on implanted intraocular lenses (IOLs) in the rabbit eye and in the mouse peritoneal space were observed using Wolter's implant cytology staining and scanning and transmission electron microscopy. In response to the implanted IOL, macrophages in the mouse peritoneal space displayed an activated form with marked ruffles on the surface. They were attached to the IOL with a broad base (sessile macrophage). The macrophages metamorphosed gradually to the flat shape of so-called epithelioid cells with many processes. They showed a tendency to fuse together or become more flat by extending the cytoplasmic lamellipodia and finally disappeared, leaving a thin membrane or a fibrous matrix. Phagocytic activity of macrophages and related cells was also observed. However, those observed on the IOL implanted in the rabbit eye showed less surface structure and appeared to adhere weakly to the IOL.

Animals↗
PubMed1988

Experimental intraocular lens implantation in the rabbit eye and in the mouse peritoneal space. Part III: Giant cell formation on the implanted lens surface.

Among the cell components appearing on an implanted intraocular lens (IOL), the macrophage is the most active participant in the foreign-body response. The morphological stages of the macrophage in the response include not only an activated form and a flat epithelioid cell, but also a giant cell observed in the later stage of the response. The giant cells on the IOLs implanted in the rabbit eye and in the mouse peritoneal space were investigated by means of Wolter's implant cytology staining and scanning and transmission electron microscopic observation. Differences in the two biological environments as the site of IOL implantation are discussed.

Animals↗
PubMed1988

Noninvasive quantitative analysis of blood oxygenation in rat skeletal muscle.

Using the isolated perfused rat hindlimb and the fluorocarbon-transfused rat, we have examined the optical characteristics of the rat skeletal muscle in the near-infrared region. The total contribution of myoglobin and cytochromes to the overall absorbance change was less than 10%. Analyzing transmitted light at 700, 730, and 805 nm, we found linear relationships between the absorbance and the hemoglobin concentrations at hematocrit values from 15 to 50% in the inflowing perfusate. Based on the relationship, we determined the ratio of absorption coefficients at 700, 730, and 805 nm of oxy- and deoxy-hemoglobins of blood in the thigh muscle. The values in thigh muscle were significantly smaller than those in hemoglobin solutions for deoxygenated blood. On the other hand, the values in thigh muscle were larger than those in hemoglobin solutions for oxygenated blood. Solving simultaneous equations by the use of these absorption coefficients, we calculated the changes in the contents of oxy-, deoxy-, and total hemoglobins in the anesthetized rat hindlimb under various conditions. The oxygen saturation of blood determined by our optical method in the thigh muscle was very close to that in the vena cava measured directly with a gas analyzer.

Animals↗