Search PubMed⌕ Search

Biomedical subjects

M Fujimoto

Publications and source records attributed to M Fujimoto.

At least 433 records · Page 24Linked to original sources
PubMed1988

Characterization of [3H]U46619 binding in pig aorta smooth muscle membranes.

The binding characteristics of [3H]U46619, a tritiated thromboxane A2/prostaglandin H2 mimetic, were studied in pig aorta smooth muscle membranes. Binding was fast, saturable, selective and reversible. The KD values determined by kinetics, equilibrium binding and drug competition methods were 68, 42 and 53 nM, respectively. The Bmax was 87.8 fmol/mg protein. Specific binding was competitively displaced by thromboxane A2/prostaglandin H2 antagonists. Binding was also displaced by prostaglandins D2, E2 and F2 alpha with IC50 values of 8, 21 and 12 microM, respectively. U46619 contracted the rat and pig aorta smooth muscle, but the response of the latter was slower than that of the former. The antagonists prevented the U46619-induced contraction of rat aorta with the same rank order as that for the inhibition of ligand binding in pig aorta smooth muscle membranes. These results provide evidence that the putative thromboxane A2/prostaglandin H2 receptor in vascular smooth muscle membranes can be detected by a ligand binding technique.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1988

The leptomenix in normal baboon brain contain receptors for dihydrotestosterone but not estradiol.

There exists a sexual dimorphism in the occurrence of meningiomas. Biochemical binding assays conducted on samples of meningiomas have indicated a high incidence of progesterone and androgen receptors in these tumors. However, similar studies have been very controversial as to the existence of estrogen receptors in these tumors. The present study was conducted to determine whether the normal leptomenix contains estrogen and androgen receptors in a primate model, namely the baboon. Three male and three female baboons were injected with either 3H-dihydrotestosterone (3H-DHT) or 3H-estradiol. One animal from each group received 3H-steroid + 100-fold unlabeled corresponding steroid to serve as control. One hour after injection of the 3H-steroids the animals were sacrificed. Their brains were removed and processed for autoradiography. Nuclear uptake and retention of 3H-DHT and/or one of its metabolites was found in 25-50% of the cells in pieces of the arachnoid adhering to the brain, cells of the glial membrane, cells in large fiber bundles, presumably oligodendroglia, and cells lining the Virchow-Robins spaces. No such localization was found with 3H-estradiol. This study provides the first anatomical evidence for the presence of androgen receptors in the normal leptomenix and glial cells of the baboon. These findings are discussed in relation to the possible clinical significance of the use of steroids to modulate the growth of meningiomas.

Animals↗
PubMed1988

Identification and isolation of a platelet GPIb-like protein in human umbilical vein endothelial cells and bovine aortic smooth muscle cells.

Glycoprotein Ib (GPIb) is an intrinsic platelet membrane protein that plays a major role in platelet adherence and mediates ristocetin-dependent platelet von Willebrand factor binding. Recent reports that the platelet membrane glycoprotein complex IIb/IIIa is expressed in several cell types prompted us to look for GPIb expression in other vascular cells. Immunoperoxidase staining of human stomach and skin histologic sections with polyclonal as well as monoclonal anti-GPIb antibody revealed the presence of GPIb in the endothelial cell and smooth muscle cell layers. Western blotting using monospecific polyclonal anti-GPIb antibodies confirmed the presence of immunoreactive GPIb in human umbilical vein endothelial and bovine aortic smooth muscle cell cultures. Fab fragments of a monoclonal anti-GPIb antibody were used to immunoprecipitate [3H]leucine labeled GPIb from metabolically labeled cells. The GPIb in these cells was functional as measured by ristocetin-dependent cell agglutination and by vWF binding. Endothelial cells as well as smooth muscle cells bound 125I-labeled vWF in a ristocetin-dependent manner, with a Kd of 7.9 nM.

Agglutination↗
PubMed1988

Expression of three viral oncogenes (v-sis, v-myc, v-fos) in primary human brain tumors of neuroectodermal origin.

We determined which viral oncogenes (v-sis, v-myc, and v-fos) were expressed in five primary human brain tumors of neuroectodermal origin (two glioblastomas multiforme, one medulloblastoma, one cystic cerebellar astrocytoma, and one ganglioglioma) and which of these oncogenes is correlated with malignancy. Using the dot hybridization technique, we determined the relative amounts of mRNA coded by these genes using the same nitrocellulose filter. The v-myc probe showed a 4- to 12-fold greater hybridization to the mRNA from two glioblastomas and the medulloblastoma (malignant group) than the mRNA from the cystic cerebellar astrocytoma or the ganglioglioma (benign group). In contrast, RNA hybridizing to v-sis and v-fos were accumulated to a greater extent in the benign tumors. These data suggest that the amount of myc expression may be correlated with the degree of malignancy of brain tumors of neuroectodermal origin.

Brain Neoplasms↗
PubMed1988

The effect of ouabain, insulin, and cyclic AMP on the acidification of luminal fluid in the proximal tubule of bullfrog kidney.

A transient urinary acidification was induced in the bullfrog proximal tubule by the peritubular administration of ouabain (10(-4) M). Insulin (200 mIU/ml) provoked a prolonged decrease of tubular fluid pH (TFpH), whereas dibutyryl cyclic AMP (10(-4) M) produced a transient increase of TFpH. The above data support the view that the urinary acidification in the proximal tubule is not explained by a simple mechanism, such as Na+/H+ exchange.

Amiloride↗
PubMed1988

The effect of cAMP on ion transport in the proximal tubular cells in bullfrog kidney.

UNLABELLED: Using a direct cellular micropuncture technique with double-barreled ion-selective microelectrodes, we investigated the effect of dibutyryl-cyclic AMP (db-cAMP) on the membrane potential and the transport of Na+, K+, and H+ in doubly-perfused bullfrog proximal tubules. The peritubular membrane potential difference (EM) and the intracellular K+, Na+ activities ((K)i, (Na)i) or intracellular and luminal pH were monitored continuously after peritubular administration of db-cAMP (10(-3)-10(-4)M). RESULTS: 1) db-cAMP hyperpolarized the EM by 8.0 mV with an increase of (K)i by 4.8 mEq/l; 2) the peritubular administration of high K+ (13.5 and 50 mM) solutions depolarized the EM by 11.5 and 41.5 mV, respectively. The high K+ perfusate with db-cAMP produced a depolarization to the same level as that in simple high K+ perfusion without db-cAMP; 3) db-cAMP transiently blocked the luminal acidification concomitantly with a cellular alkalinization by about 0.1 pH; and 4) db-cAMP caused a decrease of (Na)i by 5.0 mEq/l. CONCLUSIONS: 1) cAMP causes an increase of K+ permeability in the peritubular membrane; 2) cAMP induces a cytosol alkalosis by enhancing incorporation of H+ into the subcellular vesicles, thus favoring the activation of Na+/K+ pump; and 3) cAMP, in effect, suppresses the Na+/H+ exchange mechanism in the luminal membrane and transiently blocks the proximal urinary acidification.

Animals↗
PubMed1988

Dependence of cell pH and buffer capacity on the extracellular acid-base change in the skeletal muscle of bullfrog.

Intracellular pH was measured with single- or double-barreled liquid ion-exchanger microelectrodes in the bullfrog sartorius muscle perfused in vitro. A neutral carrier ligand was used for pH sensor of microelectrodes. Average slopes of the single-barreled microelectrodes were -56.4 +/- 1.34 mV/pH (n = 30) and the double-barreled -52.6 +/- 1.34 mV/pH (n = 65). While changing acid-base parameters of bathing media (pHe from 6.7 to 8.4, PCO2 from 3.7 to 37 mmHg, and HCO3- concentrations from 5 to 75 mM), paired muscle cell pH (pHi) and membrane potential (EM) values were determined at 23 degrees C. In control conditions (pHe = 7.6, HCO3- = 15 mM, PCO2 = 11 mmHg), pHi and EM (n = 20) averaged 6.99 +/- 0.04 (S.E.) and -69.2 +/- 2.2 mV, respectively. A negative correlation was observed between pHi and EM (correlation coefficient r = -0.564, p less than 0.002). The change in EM per unit pH change was approximately -30mV, indicating that the H+ distribution across the cell membrane only incompletely obeys the Donnan rule. The pHi varied more or less with pHe. Namely, changes in pHe and PCO2 at constant HCO3- produced relatively large changes in pHi, but elevation of pHe and HCO3- at constant PCO2 produced relatively minor rise in pHi. The stability of pHi or the size of buffer capacity were proportional to external HCO3- concentrations. These data suggested that a transmembrane distribution of buffer pairs depends largely on non-ionic diffusion of CO2-HCO3- buffer system and partly on ion fluxes of HCO3- or H+.

Acid-Base Equilibrium↗
PubMed1988

Visualization of human vestibular aqueduct with computer-aided serial section reconstruction system.

The computer-aided serial section reconstruction system (SERSERS) was employed to elucidate the entire configuration of the vestibular aqueduct in the human temporal bone. The advantages and the disadvantages of this system are discussed in comparison with several conventional methods such as X-ray visualization, plastic casting and graphic reconstruction. In spite of some limitations encountered, such as difficulty in placing a marker on each section or time consumption in data input, SERSERS can be useful in the study of the vestibular aqueduct, since a three-dimensional structure which can be observed from multidirectional aspects is reconstructed.

Computer Graphics↗
PubMed1988

The presence of a myeloid cell population showing strong reactivity with monoclonal antibody directed to difucosyl type 2 chain in epiphyseal bone marrow adjacent to joints affected with rheumatoid arthritis (RA) and its absence in the corresponding normal and non-RA bone marrow.

The presence of a specific type of cell, highly expressing difucosyl type 2 chain (dimeric Lex; FH-4 antigen), was found in the epiphyseal bone marrow cells of affected joints from patients with active severe rheumatoid arthritis (RA). The antigen was defined by monoclonal antibody FH-4 which was previously found to be directed to the oncofetal marker. The FH-4(+) cell population was identified as myeloid cell lineage with usual morphology specifically found in bone marrow of patients with severe RA, but is virtually absent in the same cell fraction of patients with osteoarthritis, infectious arthritis, and from normal adult subjects.

Adult↗
PubMed1987

Studies on estrogen induced pituitary tumor in the rat with special reference to the relationship of the tuberoinfundibular dopamine neuron system.

Pituitary tumors were experimentally induced in female Wistar rats by repeated injections of estradiol dipropionate. The hypothalamus and pituitary tumors were studied simultaneously by fluorescence histochemistry and immunohistochemistry. The pituitary gland became larger with a concomitant increase of serum prolactin in proportion to the dose of estrogen. Estrogen-induced pituitary tumor exhibited a proliferating prolactin cells by the peroxidase immunohistochemical method. Ultramicroscopical findings showed that these tumor cells were in an extremely hyperfunctional state. The dopamine neuronal perikarya in the hypothalamic arcuate nucleus and their terminals in the external layer of the median eminence were examined by fluorescence histochemistry in the rats bearing estrogen induced pituitary tumor and it was concluded that in our experimental conditions, estrogen effected directly on pituitary rather than on the hypothalamus and consequently dopamine synthesis in the arcuate neurons and its release into portal capillaries were accelerated simultaneously in order to inhibit prolactin secretion from tumor cells.

Adenoma↗