Biomedical subjects

N Takasu

Publications and source records attributed to N Takasu.

At least 55 records · Page 3Linked to original sources

PubMed1989

A new method for predicting the outcome and survival period in paraquat poisoning.

1. To elucidate the importance of lung damage in the prognosis of paraquat poisoning, the respiratory index (RI: A-aDO2/PO2) was analysed in 51 patients with paraquat poisoning. 2. Progressive deterioration of the RI was observed in 43 non-survivors, but not in 8 survivors. In addition, the RI of non-survivors became greater than 1.5 in the course of their poisoning, while that of the survivors remained less than 1.5. 3. The level of the RI (i.e. whether it became greater than 1.5 or not) was found to be a good indicator for the prognosis for life. 4. The RI-time, defined as the time taken from ingestion for the RI to be greater than 1.5, was found to be a good indicator for predicting the survival period in fatal cases. 5. As a result, we conclude that it is important and useful to examine a series of RI and the RI-time in poisoned patients not only to provide proper respiratory care, but also to predict outcome and survival period.

Adolescent↗

PubMed1989

A new variant of 17 alpha-hydroxylase deficiency with hyperaldosteronism in two Japanese sisters.

We present a report on two sisters who have 17 alpha-hydroxylase deficiency with hyperaldosteronism. They have hypertension and hypergonadotropic hypogonadism. The steroid profiles suggest that they have 17 alpha-hydroxylase deficiency. In contrast to the classical biochemical findings in 17 alpha-hydroxylase deficiency, both of these patients have hyperaldosteronism. Thus this report describes a new variant of 17 alpha-hydroxylase deficiency with hyperaldosteronism. Dexamethasone suppressed the mineralocorticoid excess, including aldosterone, and improved their hypertension. In the untreated state, ACTH, instead of the renin-angiotensin system, regulated plasma aldosterone levels, but during dexamethasone treatment the renin-angiotensin system regulated these levels.

Adolescent↗

PubMed1989

A microtestplate-immunofluorescence assay for anti-Trypanosoma cruzi antibodies.

A new microassay method for the detection of anti-Trypanosoma (T.) antibodies was developed by using Terasaki's microtestplates, and T. cruzi or other parasites were immunofluorescently labeled with polyclonal or monoclonal anti-T. cruzi antibodies. The fluorescence intensity of immunofluorescently stained parasites was assessed by either visual observation or quantitative analysis using a microscopic spectrophotometer. Although the sensitivity of the microtestplate assay was nearly equal to that of the conventional glass slide assay or ELISA, this method is easier in the assay procedures and spares the amount of antibodies and the number of target parasites requisite to the assay.

Animals↗

PubMed1989

Production and characterization of monoclonal antibodies against Trypanosoma cruzi-associated antigens.

Nine monoclonal antibodies (mAb) recognizing characteristic antigens in Trypanosoma (T.) cruzi were obtained from hybridomas which had been established by a fusion between mouse myeloma cells and the spleen cells of a mouse immune to the epimastigote form of T. cruzi (Tulahuen strain). Antigen specificities of these mAb were assessed by an indirect immunofluorescence (IIF) method using T. cruzi in different life cycles (amastigote and trypomastigote) and other members of the Trypanosomatidae. The mAb were classified into 3 groups from their reaction patterns to different parasites: 1) The strain specific mAb that reacted only with T. cruzi Tulahuen epimastigote, 2) the species specific mAb that reacted with all T. cruzi strains but not with other species of parasites, and 3) the mAb that were cross-reactive with other species of Trypanosomatidae. Most mAb were specific to epimastigote form of T. cruzi, but some reacted weakly with trypomastigote and amastigote form of the parasites. Immunoblotting and glycolipid analyses of the membrane fraction of homogenized parasites using the mAb identified at least 3 distinct antigenic molecules; those of protein nature having Mr. 43,000 and 58,000 and Mr. 43,000 and 62,000 and molecule(s) of glycolipid nature.

Animals↗

PubMed1989

Cytoplasmic pH in cultured porcine thyroid cells: alkalinization by Ca2+.

The role of calcium in cytoplasmic pH (pHi) changes was studied using 2',7'-bis(2-carboxyethyl)-5-(and 6-)carboxyfluorescein, an internalized fluorescent pH indicator, in cultured porcine thyroid cells. The Ca2+ ionophores A23187 and ionomycin stimulated thyroid cell alkalinization. An increase in cytoplasmic free calcium resulted in activation of Na+/H+ exchange which alkalinized the cells.

Animals↗

PubMed1989

Generation of hydrogen peroxide in cultured porcine thyroid cells: synergistic regulation by cytoplasmic free calcium and protein kinase C.

This study set out to elucidate the mechanism by which H2O2 generation is regulated in cultured porcine thyroid cells. We monitored continuously the effects of the calcium ionophore A23187 and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on H2O2 generation, using homovanillic acid and horseradish peroxidase. A23187 and TPA stimulated H2O2 generation. A23187 increased cytoplasmic free calcium and TPA activated protein kinase C. Generation of H2O2 is therefore regulated by cytoplasmic free calcium and protein kinase C. Exposure to A23187 or TPA augmented further the stimulation of H2O2 generation by TPA or A23187 respectively. Thus A23187 and TPA, by increasing cytoplasmic free calcium and activating protein kinase C respectively, synergistically activate H2O2 generation.

Animals↗

PubMed1989

Three-dimensional studies of cytoskeletal organizations in cultured thyroid cells by quick-freezing and deep-etching method.

Isolated porcine thyroid cells were cultured on collagen gels (control group, TSH-stimulated group, and double-layered culture). They were split or cut to remove cytoplasmic soluble proteins for replica preparations. Some specimens were immunostained with anti-actin antibody or decorated with S1 myosin fragments to identify actin filaments. The basal cell membranes of thyroid cells of monolayer culture were in contact with collagen gels and the apical cell membranes faced the culture medium. Networks of actin filaments were attached to the cytoplasmic sides of the apical cell membranes, while intermediate filaments were localized along the basal ones. The thyroid-stimulating hormone (TSH) treatment induced the formation of microvilli only on the apical cell membranes and the accumulation of actin filaments under the apical cell membranes, indicating the apical-basal polarity of the cells. In double-layered culture, the primitive follicular lumens with microvilli appeared between two adjacent cells. The interaction of cell membranes with collagen gels is a determinant factor in the orientation of apical-basal polarity. Moreover, the TSH treatment and cell-cell contact further intensify the polarization through reorganizing the cytoskeletons.

Animals↗

PubMed1989

[An undifferentiated carcinoma of the stomach--a report of 2 cases].

Two cases of an undifferentiated carcinoma of the stomach have been investigated by conventional histologic, immunohistochemical, and ultrastructural methods. The patients were a 73-year-old man and 65-year-old man. A postoperative histological examination of the resected stomach of each patient disclosed large areas of an undifferentiated carcinoma which were relatively well demarcated from areas of the adenocarcinoma. In the undifferentiated carcinomatous areas, the reticulin fiber stain was epithelial in pattern, and mucin staining proved negative. Similarly both Grimelius and Fontana-Masson staining also negative. In like manner immunostains using cytokeratin , vimentin , IgG, IgA, s-100 protein, and NSE were all negative, and an electron microscopic study showed no neurosecretory granules or mucin secretory granules. Based on these findings, the diagnosis of either a malignant lymphoma or small cell anaplastic carcinoma could be excluded, and thus an undifferentiated carcinoma was the determination.

Adenocarcinoma↗

PubMed1988

Cytoplasmic pH in the action of epidermal growth factor (EGF) in cultured porcine thyroid cells.

We demonstrate measurement of cytoplasmic pH (pHi), using 2',7'-bis(2-carboxyethyl)-5 (and 6-) carboxyfluorescein (BCECF), and internalized fluorescent pHi indicator, in thyroid cells. Using cultured porcine thyroid cells, we studied the effects of epidermal growth factor (EGF) on pHi and [3H] thymidine incorporation; 10 nM EGF alkalinizes thyroid cells and stimulates thymidine incorporation. The results indicate that Na+/H+ exchange or cell alkalinization may function as a transmembrane signal transducer in the action of EGF in the thyroid cells.

Animals↗

PubMed1988

Hydrogen peroxide generation in whole rat pancreatic islets; synergistic regulation by cytoplasmic free calcium and protein kinase-C.

This is the first report to show that pancreatic islet cells generate H2O2 and this H2O2 generation is regulated synergistically by cytoplasmic free calcium ([Ca2+]i) and protein kinase-C. Effects of calcium ionophore A23187 and 12-O-tetradecanoylphorbol 13-acetate (TPA), a tumor promoter, on H2O2 generation were studied in whole pancreatic islets obtained from male Wistar rats. We employed A23187 to elevate cytoplasmic free calcium, and TPA to activate protein kinase-C and monitored continuously their effects on H2O2 generation, measured using homovanillic acid and horseradish peroxidase. A23187 stimulates H2O2 generation. TPA, which activates protein kinase-C, augments this A23187-stimulated H2O2 generation. H2O2 generation is stimulated by an increase in [Ca2+]i and regulated synergistically by [Ca2+]i and protein kinase-C.

Animals↗

PubMed1988

Morphological identification of an interneuron in the hypoglossal nucleus of the rat: a combined Golgi-electron microscopic study.

Hypoglossal small neurons of adult and juvenile (10-15-day-old) rats were examined by a combined Golgi-electron microscopic technique. In adult rats, Golgi-impregnated neurons were fusiform or ovoid (17 X 12 micron) and emitted a few primary dendrites with few branches and few spines and an axon mainly from the proximal portion of the primary dendrite. At the ultrastructural level, the soma displayed an invaginated nucleus with a conspicuous nucleolus and a relatively scanty cytoplasm in which cisternae of rough endoplasmic reticulum were not organized into extensive lamellar arrays. A moderate number of axon terminals, which contained spherical clear or pleomorphic vesicles approximately 25-40 nm in diameter, formed symmetric or asymmetric synapses on the soma, the dendrites, the axon hillock, and the initial segment. In a preparation from the juvenile rat, we could trace a full axon trajectory of the small neuron. In this sample, in which a small neuron and a motoneuron were simultaneously impregnated, the axon of the small neuron was found to receive an axoaxonic symmetric synapse with pleomorphic vesicles on a varicosity and to contact the motoneuron dendrites by means of another varicosity of the main axon and of two boutons from an axon collateral. The varicosity and the boutons contained pleomorphic synaptic vesicles and synapsed symmetrically with the motoneuron dendrites. We identified the small neuron in the rat hypoglossal nucleus morphologicaly as a Golgi type II interneuron. We discuss its function in relation to the GABAergic nature of small neurons (Takasu et al.: J. Comp. Neurol. 263:42-53, '87).

Age Factors↗

PubMed1988

Epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium in cultured porcine thyroid cells.

The initial signal for thyroid cell proliferation is unknown. This is the first report to show that epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium ([Ca2+]i) in the thyroid gland. In cultured porcine thyroid cells, 10 nM EGF produces a breakdown of phosphatidylinositol and stimulates inositol phosphate production. Ten nM EGF increases [Ca2+]i, measured using fura-2, a fluorescent Ca2+ indicator; the EGF-induced [Ca2+]i response occurs immediately, reaches a maximum within several seconds, and then slowly declines. EGF stimulates production of inositol phosphates, which seem to increase [Ca2+]i. Inositol phosphate production and an increase in [Ca2+]i after EGF-stimulation may function as an initial signal for thyroid cell proliferation.

Animals↗

PubMed1988

Polarized thyroid cells in monolayers cultured on collagen gel: their cytoskeleton organization, iodine uptake, and resting membrane potentials.

Porcine thyroid cells were cultured on collagen gel-coated cover glasses. They were reorganized into polarized monolayer cells; the basal cell membranes were in contact with the collagen gel, and the apical ones faced the culture medium. We studied cytoskeleton organization, resting membrane potentials, and iodine uptake of these cells. The quick-freezing and deep-etching replica method provided three-dimensional images of the cytoskeleton organization. Networks of microfilaments were observed under the apical cell membrane. In the deep cytoplasm and near the basal cell membranes, intermediate filaments predominated and were interlinked with the microfilaments. When the cells were cultured in the presence of TSH, TSH induced the formation of microvilli at the apical cell membranes and the accumulation of microfilaments under these membranes; in the deep cytoplasm, the intermediate filaments were more closely interlinked with the microfilaments. The microfilaments were immunostained with antiactin antibody. Thus, collagen is a factor in determining the cell polarity, and TSH further augments polarization through reorganizing the cytoskeletons. Electrophysiological study revealed that the resting membrane potential of cells cultured in the absence of TSH was -46 mV, and that of cells cultured in the presence of TSH was -58 mV. TSH hyperpolarized resting membrane potentials. These cells took up iodine. TSH in the medium augmented this uptake. TSH augments thyroid cell polarization through reorganizing the cytoskeletons and hyperpolarizing the resting membrane potentials and enhances iodine uptake by the cells.

Animals↗

PubMed1988

Thyrotrophin and prostaglandin E2 increase calmodulin levels and cyclic AMP phosphodiesterase activity in cultured porcine thyroid cells.

Thyrotrophin (TSH) and prostaglandin E2 (PGE2) increased cellular cyclic AMP (cAMP), calmodulin levels and cAMP phosphodiesterase activity in cultured porcine thyroid cells. Dibutyryl cAMP (dbcAMP), a stable analogue of cAMP, increased calmodulin levels and cAMP phosphodiesterase activity. These results indicate that TSH- and PGE2-stimulated increases in calmodulin are mediated by cAMP. This increased concentration of calmodulin in turn stimulates cAMP phosphodiesterase. Double reciprocal plots of cAMP hydrolysis yielded two apparent Michaelis constants (Km); the lower in the 1 mumol/l and the higher in the 10 mumol/l range. Thyrotrophin, PGE2 and dbcAMP increased the values of maximal velocity without changing the Km values.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1987

Epidermal growth factor (EGF), tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) and calcium ionophore A23187 increase cytoplasmic free calcium and stimulate arachidonic acid release and PGE2/6-keto PGF1 alpha production in cultured porcine thyroid cells.

Epidermal growth factor (EGF), 12-O-tetradecanoylphorbol 13-acetate (TPA) and calcium ionophore A23187 increase cytoplasmic free calcium ([Ca2+]i) and stimulate arachidonic acid release and production of PGE2 and 6-keto PGF1 alpha, an end metabolite of PGI2, in cultured porcine thyroid cells. Addition of EGF, TPA or A23187 to the cells loaded with fura-2, a fluorescent Ca2+ indicator, causes an immediate increase in [Ca2+]i, which is the earliest event after mitogen stimulation. This [Ca2+]i response occurs immediately, reaching a maximum within several seconds. EGF, TPA and A23187 stimulate arachidonic acid release and PGE2 and 6-keto PGF1 alpha production; the maximum effects are obtained after 2-4 h incubation. EGF, TPA and A23187 increase [Ca2+]i and then stimulate arachidonic acid release and PG production.

6-Ketoprostaglandin F1 alpha↗

PubMed1987

Generation of H2O2 is regulated by cytoplasmic free calcium in cultured porcine thyroid cells.

Effects of calcium ionophore A23187 and BAY-K-8644, a calcium channel agonist, on cytoplasmic free calcium ([Ca2+]i) and H2O2 generation were studied in cultured porcine thyroid cells. We monitored continuously the effects of A23187 and BAY-K-8644 on [Ca2+]i and H2O2 generation, using the intracellularly trapped fluorescent Ca2+ indicator, fura-2, and homovanillic acid, respectively. A23187 and BAY-K-8644 induce an immediate increase in [Ca2+]i and H2O2 generation. The A23187- and BAY-K-8644-induced [Ca2+]i responses and H2O2 generation occur immediately, reach a maximum within several seconds, and then slowly decline. The minimum doses of A23187 or BAY-K-8644 to increase [Ca2+]i stimulate H2O2 generation. H2O2 generation is regulated by [Ca2+]i.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1987

Immunocytochemical localization of gamma-aminobutyric acid in the hypoglossal nucleus of the macaque monkey, Macaca fuscata: a light and electron microscopic study.

The hypoglossal nucleus of the macaque monkey Macaca fuscata was investigated with light and electron microscopic immunocytochemistry with an antibody directed against gamma-aminobutyric acid (GABA). At the light microscopic level, GABA immunoreactivity was present in small neurons, punctate structures, and thin, fiberlike structures. These GABA-positive elements were distributed throughout the hypoglossal nucleus at rostrocaudal levels. There was no immunoreactivity in the hypoglossal motoneurons. The GABA-positive small neurons were fusiform or ovoid (15 X 9 micron) and extended a few proximal dendrites from both poles. At the ultrastructural level, these small neurons were characterized by a markedly invaginated nucleus and a scanty cytoplasm in which cisternae of rough endoplasmic reticulum were not organized into extensive lamellar arrays as seen in the motorneurons. The GABA-positive punctate structures at the light microscopic level were identified as vesicle-containing axon boutons at the electron microscopic level. These GABA-positive axon terminals made synaptic contacts mainly with the dendrites of the motoneurons and infrequently with the somata. The majority of them made symmetric synapses and they contained pleomorphic synaptic vesicles. However, a small number of GABA-positive terminals (7%) formed asymmetric synapses with the dendrites of motoneurons, and these contacts exhibited postsynaptic dense bars or Taxi bodies lying beneath the postsynaptic membranes. There were no GABA-positive boutons that contacted the cell bodies of the small neurons. Although GABA-positive myelinated and unmyelinated axons were seen as thin, fiberlike structures, these myelinated and unmyelinated axons rarely gave rise to boutons on the motoneurons. The present study suggests that GABAergic inhibition in the monkey hypoglossal nucleus occurs mainly on the dendrites of the motoneurons and to some extent on the somata.

Animals↗

PubMed1987

Epidermal growth factor (EGF) and tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulate PG synthesis and thymidine incorporation in cultured porcine thyroid cells.

This is the first report to show that epidermal growth factor (EGF) and 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulate the production of PGE2 and 6-keto PGF1 alpha, an end metabolite of PGI2, in the thyroid gland. In cultured porcine thyroid cells, EGF and TPA stimulate PGE2 and 6-keto PGF1 alpha production; the maximum PG levels were obtained after 3-4 h incubation with EGF or TPA; the addition of as little as 10(-11) M EGF or 5 X 10(-11) M TPA resulted in increases in PGE2 and 6-keto PGF1 alpha, and the maximum levels were obtained with 10(-8)-10(-7) M EGF or TPA. This report also shows that EGF and TPA stimulate [3H] thymidine incorporation.

6-Ketoprostaglandin F1 alpha↗