Search PubMed⌕ Search

Biomedical subjects

T Ohtsuka

Publications and source records attributed to T Ohtsuka.

At least 253 records · Page 14Linked to original sources
PubMed1990

Effect of glutaraldehyde on NADPH oxidase system of guinea pig polymorphonuclear leukocytes.

In an attempt to elucidate properties and activation mechanisms of the NADPH oxidase system, which is known to be responsible for the production of superoxide anion (O2-) in cell membranes of polymorphonuclear leukocytes (PMNL), intact guinea pig PMNL were treated with glutaraldehyde, a protein crosslinking reagent, before or after stimulation with phorbol 12-myristate 13-acetate (PMA). Then, PMNL were disrupted and NADPH oxidase activity was measured. After the treatment of resting PMNL with glutaraldehyde, NADPH oxidase was no longer activated by PMA. On the other hand, the NADPH oxidase activity enhanced by PMA in advance was markedly retained by the glutaraldehyde treatment of such PMA-stimulated PMNL as compared to that in untreated cells. Similar retention by glutaraldehyde of the stimulated NADPH oxidase activity was observed in PMNL stimulated by formyl-methionyl-leucyl-phenylalanine (FMLP) and cytochalasin D. Furthermore, the oxidase activity of glutaraldehyde-treated PMNL was stable during incubation at 37 degrees C, the half life of the oxidase activity of the treated PMNL being more than 90 min whereas that of the untreated PMNL is about 15 min. This ability of the glutaraldehyde treatment to retain the activity was also observed against inactivation by high concentrations of NaCl and by positively charged alkylamine.

Aldehydes↗
PubMed1990

Botulinum ADP-ribosyltransferase activity as affected by detergents and phospholipids.

GTP-binding proteins with Mr values of 22,000 and 25,000 in bovine brain cytosol were ADP-ribosylated by an exoenzyme (termed C3) purified from Clostridium botulinum type C. The rate of C3-catalyzed ADP-ribosylation of the partially purified substrates was extremely low by itself, but was increased enormously when a protein factor(s) obtained from the cytosol was simultaneously added. The rate of the C3-catalyzed reaction was also stimulated by the addition of certain types of detergents or phospholipids even in the absence of the protein factors. The ADP-ribosylation appeared to be enhanced to an extent more than the additive effect of either the protein factors or the detergents (and phospholipids). Thus, ADP-ribosylation catalyzed by botulinum C3 enzyme was affected not only by cytoplasmic protein factors but also by detergents or phospholipids in manners different from each other.

ADP Ribose Transferases↗
PubMed1990

Electron microscopic study of immunocytochemically labeled centrifugal fibers in the goldfish retina.

The centrifugal fibers innervating the goldfish retina were studied quantitatively by light and electron microscopy. These fibers originating from cell bodies in the olfactory bulb were labeled by antiserum to the tetrapeptide Phe-Met-Arg-Phe-NH2 (FMRFamide). The number of FMRFamide-immunoreactive (ir) centrifugal fibers in each eye of the adult goldfish (body length: 12-15 cm) was 65 +/- 14 (mean +/- S.D., n = 7). All of these fibers in the optic nerve and the retina were unmyelinated. Each FMRFamide-ir centrifugal fiber runs along the optic fiber layer and gives several terminal arborizations in the outermost layer (layer 1) of the inner plexiform layer. Layer 1 is, therefore, densely covered by a plexus of terminal arborizations. Along these terminal arborizations, we found output synapses characterized by a cluster of small clear vesicles (40 nm in diameter) at the presynaptic site and a thickened membrane in the apposed retinal cell processes. In a sample area of 2,000 microns 2, such synapses occurred at a density of one per 105 microns 2, or about 13,000 per centrifugal fiber. Thus, the FMRFamide-ir centrifugal fibers are likely to modulate retinal cell activity through an estimated total of 840,000 output synapses per retina.

Animals↗
PubMed1990

Telodendrial contact of HRP-filled photoreceptors in the turtle retina: pathways of photoreceptor coupling.

Synaptic contacts of photoreceptors in the turtle retina were studied by intracellular injection of horseradish peroxidase (HRP) and electron microscopy. Both cone and rod photoreceptors radiated basal processes (telodendria) from their terminal endings. These telodendria ran laterally in the outer plexiform layer. The telodendria of cones gave rise to many fine branches that penetrated synaptic cavities of several neighboring cones. Tips of these branches terminated near the walls of synaptic cavities. Some of the telodendrial contact formed two types of basal junction: symmetrical and punctate. The distribution of cones that made telodendrial contacts with the HRP-filled cone were quantitatively investigated. Green-sensitive cones (n = 3) made telodendrial contacts with neighboring red- and blue-sensitive cones, blue-sensitive cones (n = 4) with red- and green-sensitive cones, and red-sensitive cones (n = 9) with red- and green-sensitive cones. In contrast to these cone connections, rod telodendria did not penetrate neighboring photoreceptors. Direct synaptic contacts were not found between rods and cones. Our results clarify the variety of cone couplings in turtle retina: the three chromatic classes of cones are selectively coupled by the basal junctions at the ends of telodendrial processes.

Animals↗
PubMed1990

Involvement of membrane charges in constituting the active form of NADPH oxidase in guinea pig polymorphonuclear leukocytes.

NADPH oxidase activity in a membrane fraction prepared from phorbol 12-myristate 13-acetate (PMA)-stimulated guinea pig polymorphonuclear leukocytes (PMNL) was inhibited by positively charged myristylamine. The inhibitory effect of myristylamine was significantly suppressed by simultaneous addition of a negatively charged fatty acid, such as myristic acid. However, the suppression by myristylamine was not sufficiently restored when myristic acid was added later. On the other hand, pretreatment of PMA-stimulated PMNL with glutaraldehyde, a protein crosslinking reagent, stabilized NADPH oxidase activity against inhibition by myristylamine, but not against that by p-chloromercuribenzenesulfonic acid. In a cell-free system of reconstituted plasma membrane and cytosolic fractions prepared from unstimulated PMNL, arachidonic acid-stimulated NADPH oxidase activity was also inhibited by myristylamine. During the activation of NADPH oxidase by PMA in intact PMNL and by arachidonic acid in the cell-free system, cytosolic activation factor(s) translocated to plasma membranes. The bound cytosolic activation factor(s) was released from the membranes by myristylamine, accompanied by a loss of NADPH oxidase activity. It is plausible from these results that the inhibitory effect of alkylamine on NADPH oxidase is due to induction of the decoupling and/or dissociation of the cytosolic activation component(s) from the activated NADPH oxidase complex by increments of positive charges in the membranes, and that the glutaraldehyde treatment prevents the dissociation of component(s).

Amines↗
PubMed1990

Monoclonal antibody labels both rod and cone outer segments of turtle photoreceptors.

We have studied the immunoreactivity of turtle photoreceptors to a monoclonal antibody (MAb 15-18) which binds to the external loop connecting bovine rhodopsin helices IV-V. Three chromatic types of cone photoreceptors were identified by the presence and color of oil droplets. MAb 15-18 intensely labeled the outer segments of both rods and green cones. In addition, a weak cross-reactivity was also found in the outer segments of red cones having a pale-green oil droplet, and of blue cones. Other morphological subtypes of red cones, cones with a red oil droplet and both members of double cones, showed no labeling. Our results indicate that rhodopsin and green cone opsin have a similar antigenic determinant, and that two different structural forms of red cone opsin may be present in the turtle retina.

Animals↗
PubMed1990

Translocation of the 46 kDa protein(s) in response to activation of NADPH oxidase in guinea pig polymorphonuclear leukocytes.

Treatment of guinea pig polymorphonuclear leukocytes (PMNL) with phorbol 12-myristate 13-acetate (PMA) induced an increase in phosphorylation of 46 kDa protein(s) in parallel with activation of NADPH oxidase. In response to PMA stimulation, phosphorylated 46 kDa protein(s) increased markedly in the membrane fraction, accompanied by a decrease in the unphosphorylated form(s) in the cytosol. The results indicate that the 46 kDa protein(s) may be translocated concomitantly with its phosphorylation. On the other hand, in a cell-free activation system reconstituted from the cytosol and plasma membranes of unstimulated PMNL, arachidonic acid caused the translocation of the 46 kDa protein(s) from the cytosol to the plasma membranes concomitantly with an enhancement of NADPH oxidase activity. These results suggest that activation of NADPH oxidase is dependent on an association of 46 kDa protein(s) with the membranes both in intact PMNL and in the cell-free system.

Amino Acids↗
PubMed1990

Dipalmitoylphosphatidylcholine (L-alpha-lecithin) stimulates prostaglandin E production in human amnion.

The effect of dipalmitoylphosphatidylcholine (DPPC, L-alpha-lecithin), a substance not containing arachidonic acid, on prostaglandin E (PGE) production of amniotic membrane was studied. DPPC (3.125-800 micrograms/ml) stimulated PGE production of amniotic membrane (150-200%), suggesting that lecithin, the major surfactant component, is directly involved in the mechanism of human parturition as a stimulator of PGE production.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

Hyperthyrotropinemia in a neonate with normal thyroid hormone levels: the earliest diagnostic clue for pseudohypoparathyroidism.

A neonatal case of hyperthyrotropinemia is described in association with pseudohypoparathyroidism (PHP). This girl was found to have high serum thyrotropin (TSH) on screening, though serum thyroid hormones were within the normal ranges throughout the observation. The patient's TSH remained above the normal limit until 5 years of age, when she suffered from hypocalcemic tetany and was diagnosed as type-1 PHP on the basis of responsiveness to parathyroid hormone. She also had stigmata of Albright's hereditary osteodystrophy. The results demonstrate that elevated TSH, although thyroid hormone concentrations are normal and medication is not indicated, may be one of the earliest diagnostic clues for PHP.

Calcium↗
PubMed1990

Mechanism for the inhibitory effect of a seleno-organic compound, Ebselen, and its analogues on superoxide anion production in guinea pig polymorphonuclear leukocytes.

Effects of Ebselen and its analogs (PZ-25, NAT06-123, NAT02-761, NAT02-801, NAT06-099, and NAT06-513) on superoxide anion (O2-) production induced by tetradecanoyl phorbol acetate (TPA) were examined in intact guinea pig polymorphonuclear leukocytes (PMNL). Four compounds having a structure of 1,2 benzoisoselenazol-3-(2H) one (Ebselen, NAT06-123, and NAT02-761) and its sulfur-substituted analog (PZ-25), had a potent inhibitory effect on O2- production as compared with others. Ebselen and NAT06-123 also markedly inhibited nicotinamide adenine dinuclestide phosphate (NADPH) oxidase activity, which is responsible for O2- production in intact cells, and in a particulate fraction prepared from TPA-stimulated PMNL, whereas PZ-25 inhibited this enzyme weakly and NAT02-761 did not. On the other hand, Ebselen and PZ-25 had the same degree of potent inhibitory effect on protein kinase C which was involved in the regulation of NADPH oxidase activation. Thus, it is plausible that inhibition of O2- production in intact PMNL by these compounds were due not only to direct inhibition of NADPH oxidase but also to inhibition of protein kinase C.

Animals↗
PubMed1990

[Transient dysfibrinogenemia and cerebral thrombosis following remission induction therapy for acute lymphoblastic leukemia].

A 38-year-old female with acute lymphoblastic leukemia developed monoplegia of the left upper extremity following chemotherapy for remission induction consisting of vincristine, prednisolone, cyclophosphamide, adriamycin and methotrexate. Hemorrhagic infarction due to thrombosis of the right cortical vein was diagnosed by brain images using computed tomography and magnetic resonance imaging in addition to the clinical course. At this time, a plasma level of fibrinogen measured by the thrombin time method had decreased to 84 mg/dl, while its antigenicity was 276 mg/dl. There was no evidence of activation of the blood coagulation and fibrinolysis system nor of abnormal liver function. A mixing test with normal plasma disclosed the absence of an inhibitory factor against fibrin polymerization in her plasma. Fibrinogen levels as assessed by the thrombin time method recovered to the antigenicity level one and half months later. The discrepancy between the activity and antigenicity of fibrinogen indicated the occurrence of acquired dysfibrinogenemia, probably induced by antileukemic agents. Thus, it is suggested that dysfibrinogenemia is a possible cause of cerebral thrombosis in this patient.

Adult↗
PubMed1990

[Study on postoperative perforation in patients with chronic empyema--reoperated cases].

In 18 cases undergone reoperation because of perforation after the initial operation for primary and secondary chronic empyema during the period from 1974 through August 1986, we evaluated findings of fistula, procedures and causes of failure of the initial operation, and procedures and results of reoperation. Subjects consisted of 16 cases of chronic empyema complicated with pulmonary tuberculosis, 1 case of group III nontuberculous mycobacteriosis, and 1 case of chronic empyema secondary to pulmonary fibrosis. All patients had fistula at the initial operation. The initial operation was performed by Kinchu method in 8 cases, pulmonary detachment in 6 cases, and thoracic cavity reduction chiefly by a modification of Grow's method in 4 cases. The initial operation failed because of incomplete closure of the fistula in 11 cases (61%) and appearance of new fistula in 7 cases (39%). In reoperation, the fistula was closed by pedicle muscle plombage in 1 case undergone the initial operation by Kinchu method, while thoracic cavity reduction chiefly by a modification of Grow's method in all of the other 17 cases. After the operation, 15 patients (83%) were cured, 16 patients (89%) could be socially rehabilitated and 2 patients (11%) had recurrence of empyema. Two recurrent patients died from hepatitis and exacerbation of nontuberculous mycobacteriosis, respectively. Out of 10 patients undergone pedicle muscle plombage, 8 patients (80%) were cured. From these findings, we consider that the results of one stage operation can be improved by applying pedicle muscle plombage for closure of fistula after the initial operation following treatment with effective antibiotics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Activator protein supporting the botulinum ADP-ribosyltransferase reaction.

The ADP-ribosyl moiety of NAD was transferred to proteins with Mr values of 22,000 and 25,000 when bovine brain cytosol was incubated with a botulinum ADP-ribosyltransferase C3 (BT-C3) which was purified from the culture medium of a type C strain of Clostridium botulinum. Any protein fraction eluted from a chromatographic column to which the cytosol had been applied, however, was not significantly ADP-ribosylated by BT-C3, unless the reaction mixture was further supplemented with a small amount of the cytosol. Thus, substrate protein(s) could be partially purified based on their ability to be ADP-ribosylated by BT-C3 in the presence of the cytoplasmic activator(s). The rate of ADP-ribosylation of the substrates was extremely low by itself but was increased enormously and progressively when increasing amounts of cytosol were added, affording a reliable means for assay of the activator contained therein. The activator was separated from the substrate proteins and partially purified from the cytosol by sequential chromatography steps with an anion exchanger and a gel filtration column. The activity of the partially purified activator was heat-labile and protease-sensitive, suggesting that the activator was a protein or had a protein component necessary for activity. The action of the activator protein(s) was specific for BT-C3-catalyzed ADP-ribosylation; cholera toxin-catalyzed ADP-ribosylation of GTP-binding protein (Gs) was not supported by this activator. Thus, this is the first report to show that botulinum ADP-ribosyltransferase-catalyzed reaction can proceed significantly only in the presence of other protein factor(s), just as has been observed with an ADP-ribosylation factor required for cholera toxin-induced similar reaction.

ADP Ribose Transferases↗
PubMed1989

Synergism between protein kinase C activator and fatty acids in stimulating superoxide anion production in guinea pig polymorphonuclear leukocytes.

Treatment of guinea pig polymorphonuclear leukocytes (PMNL) with various fatty acids elicited superoxide anion (O2-) production and an increase in intracellular Ca2+ [( Ca2+]i). Both responses, however, were seldom observed when PMNL were treated at lower concentrations. But, simultaneous addition of 1-oleoyl-2-acetylglycerol (OAG), a protein kinase C activator, caused an increase in O2- production even at the lower concentrations of fatty acids. In contrast to the synergism in O2- production, [Ca2+]i remained at almost the basal level irrespective of the presence of OAG. Among saturated fatty acids, those with carbon numbers of 14 to 18 were most effective in stimulating O2- production in combination with OAG. Unsaturated fatty acids with a carbon number of 18 were almost equally effective irrespective of the number of double bonds.

Animals↗
PubMed1989

Stimulatory effects of a short chain phosphatidate on superoxide anion production in guinea pig polymorphonuclear leukocytes.

Treatment of guinea pig polymorphonuclear leukocytes (PMNL) with a phosphatidate containing short-chain fatty acids, 1,2-didecanoyl-3-sn-phosphatidate (PA10), induced substantial superoxide anion (O2-) production in a dose-dependent manner, whereas phosphatidates prepared from egg lecithin and 1,2-dioleoyl-3-sn-phosphatidate (PA18:1) had no such effect. Calcium was not involved in PA10-induced O2- production, since the production was also observed in the case of addition of EGTA prior to PA10 or pretreatment of PMNL with quin-2 and EGTA to eliminate contributions of both extracellular and intracellular calcium. We have reported in previous papers that the phosphorylation of 46K protein(s), which was commonly observed in parallel with an activation of NADPH oxidase in PMNL, was increased by treatment with 10 microM 1-oleoyl-2-acetylglycerol (OAG) with little change in the O2- production (Okamura et al. (1984) Arch. Biochem. Biophys. 228, 270-277; Ohtsuka et al. (1988) Arch. Biochem. Biophys. 260, 226-231). Treatment of PMNL with a combination of PA10, which slightly increased 46K protein phosphorylation, and such a low concentration of OAG induced a marked increase in the O2- production with the increase in 46K protein phosphorylation, which was probably due to OAG action. Thus, it is likely that this protein phosphorylation plays a significant role in the stimulation of the O2- production by phosphatidate in PMNL.

Animals↗