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31.
Abstract: Arachidonic acid and oleoylacetylglycerol enhance depolarization-evoked glutamate release from hippocampal mossy fiber nerve endings. It was proposed this is a Ca2+ -dependent effect and that protein kinase C is involved. Here we report that arachidonic acid and oleoylacetylglycerol synergistically potentiate the glutamate release induced by the Ca2+ ionophore ionomycin. The Ca2+ dependence of this effect was established, as removal of Ca2+ eliminated evoked release and the lipid-dependent potentiation. Also, Ca2+ channel blockers attenuated ionomycin- and KCI-evoked exocytosis, as well as the facilitating effects of the lipid mediators. Although facilitation required Ca2+ , it may not involve an enhancement of evoked Ca2+ accumulation, because ionomycin-dependent glutamate release was potentiated under conditions that did not increase ionomycin-induced Ca2+ accumulation. Also, the facilitation may not depend on inhibition of K+ efflux, because enhanced release was observed in the presence of increasing concentrations of 4-aminopyridine and diazoxide did not reduce the lipid-dependent potentiation of exocytosis. In contrast, disruption of cytoskeleton organization with cytochalasin D occluded the lipid-dependent facilitations of both KCI- and ionomycin-evoked glutamate release. In addition, arachidonic acid plus glutamatergic or cholinergic agonists enhanced glutamate release, whereas a role for protein kinase C in the potentiation of exocytosis was substantiated using kinase inhibitors. It appears that the lipid-dependent facilitation of glutamate release from mossy fiber nerve endings requires Ca2+ and involves multiple presynaptic effects, some of which depend on protein kinase C. 相似文献
32.
Paula C. Southwick Susan K. Yamagata Charles L. Echols Jr. Gail J. Higson Scott A. Neynaber Robert E. Parson William A. Munroe 《Journal of neurochemistry》1996,66(1):259-265
Abstract: The principal constituent of amyloid plaques found in the brains of individuals with Alzheimer's disease (AD) is a 39–42-amino-acid protein, amyloid β protein (Aβ). This study examined whether the measurement of Aβ levels in CSF has diagnostic value. There were 108 subjects enrolled in this prospective study: AD (n = 39), non-AD controls (dementing diseases/syndromes; n = 20), and other (n = 49). CSF was obtained by lumbar puncture, and Aβ concentrations were determined using a dual monoclonal antibody immunoradiometric sandwich assay. The mean Aβ value for the AD group (15.9 ± 6.8 ng/ml) was not significantly different from that for the non-AD control group (13.0 ± 7.1 ng/ml; p = 0.07), and substantial overlap in results were observed. Aβ values did not correlate with age ( r = −0.05, p = 0.59), severity of cognitive impairment ( r = 0.22, p = 0.21), or duration of AD symptoms ( r = 0.14, p = 0.45). These findings are in conflict with other reports in the literature; discrepant results could be due to the instability of Aβ in CSF. Aβ immunoreactivity decays rapidly under certain conditions, particularly multiple freeze/thaw cycles. Use of a stabilizing sample treatment buffer at the time of lumbar puncture allows storage of CSF without loss of Aβ reactivity. In conclusion, the total CSF Aβ level is not a useful marker for current diagnosis of AD. 相似文献
33.
Claudia Gaspar Iscia Lopes-Cendes Anita L. DeStefano Patrícia Maciel Isabel Silveira Paula Coutinho Patrick MacLeod Jorge Sequeiros Lindsay A. Farrer G. A. Rouleau 《Human genetics》1996,98(5):620-624
Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar degeneration originally described in families of Portuguese-Azorean
ancestry. The hypothesis that its present world distribution could result from the spread of an original founder mutation
has been raised. To test this possibility we have conducted a linkage disequilibrium study of markers segregating with the
MJD1 locus in a total of 64 unrelated families of different geographical origins. Significant association was detected between
the MJD1 locus and marker alleles at loci D14S280, D14S1050 and D14S81. All affected individuals, except one Chinese family, had allele
3 (237 bp) at D14S280. This finding is consistent with a founder effect in our MJD population. However, distinct haplotypes
were observed in patients originating from the two Azorean islands showing the highest disease prevalence; therefore, the
possible existence of more than one founder mutation can not be excluded with the markers currently available.
Received: 27 February 1996 / Revised: 4 June 1996 相似文献
34.
Paula P. Chee 《Plant cell reports》1996,16(3-4):184-187
Summary Taxusbrevifolia is the source of paclitaxel (Taxol®), an anticancer drug. A method for regeneration ofTaxus brevifolia from immature zygotic embryos via somatic embryogenesis is described. Embryogenic callus tissues were obtained by culturing immature zygotic embryos on Lloyd and McCown medium (MCM) supplemented with 160 M 2,4-dichlorophenoxyacetic acid (2,4-D) + 5 M benzylaminopurine (BA) + 5 M naphthaleneacetic acid (NAA) for 4 weeks. Putative embryoids were obtained following transfer of cultures to MCM medium supplemented with 4 M BA + 5 M kinetin + 1 M NAA for 6 to 8 weeks. Conversion of embryos was obtained on MCM medium supplemented with 40 M abscisic acid (ABA) + 1% activated charcoal. Development of bipolar structures with recognizable shoot and root apices was observed in somatic embryos. Five percent of somatic embryos were regenerated into plantlets on half-strength growth regulator-free MCM medium. 相似文献
35.
David H. Lewis Garry K. Burge David M. Schmierer Paula E. Jameson 《Physiologia plantarum》1996,98(1):179-186
The cytokinin content in fruit tissue of the kiwifruit ( Actinidia deliciosa [A. Chev.] C. F. Liang et A. R. Ferguson var. deliciosa cv. Hayward) was monitored during fruit development to identify which cytokinins were present and if they were linked with specific stages of fruit growth. Cytokinins were isolated and purified by column chromatography and high-performance liquid chromatography and quantified by radioimmunoassay. A novel HPLC step utilising an amine column was successfully introduced as a preparative step in the separation of the O - and 9-glucosides from the free bases and ribosides. The radioimmunoassay results were validated, and the different cytokinins identified, by gas chromatography-mass spectrometry. Cytokinins detected in fruit included the cytokinin free bases, zeatin and isopentenyladenine, their ribosides, nucleotides and both O - and 9-glucosides. Both qualitative and quantitative changes of the cytokinins occurred during fruit development. A decrease in cytokinin concentration occurred after anthesis (from 342 pmol g−1 fresh weight at anthesis to 41 pmol g−1 fresh weight 27 days after anthesis). A large increase in cytokinin concentration and content per fruit occurred as the fruit reached commercial maturity (to 1900 pmol g−1 fresh weight). Individual cytokinins showed quite different patterns. Zeatin, in particular, showed a peak in concentration (13 pmol g−1 fresh weight) 11 days after anthesis that correlated with the beginning of the cell division phase of fruit growth. The accumulation of cytokinin (mostly zeatin riboside or zeatin nucleotide) in mature fruit may be of significance for the postharvest storage of kiwifruit fruit. 相似文献
36.
Graciela C. Theiler Yanina C. Marcos Edgardo Kolkowski Nancy Lindel Mónica Capucchio Paula Barrionuevo Francisco R. Carnese M. Leonardo Satz 《Immunogenetics》1996,43(6):398-399
The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number U17107. The nameB*3509 was officially assigned by the WHO Nomenclature Committee in December 1994 相似文献
37.
A Familial Factor Independent of CAG Repeat Length Influences Age at Onset of Machado-Joseph Disease 总被引:3,自引:0,他引:3
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Anita L. DeStefano L. Adrienne Cupples Patricia Maciel Claudia Gaspar Joao Radvany David M. Dawson Lewis Sudarsky Lee Corwin Paula Coutinho Patrick MacLeod Jorge Sequeiros Guy A. Rouleau Lindsay A. Farrer 《American journal of human genetics》1996,59(1):119-127
Machado-Joseph disease (MJD) is a late-onset, progressive, neurodegenerative disorder caused by the expansion of an unstable trinucleotide (CAG) repeat sequence in a novel gene (MJD1) on chromosome 14. Previous studies showed that age at onset is negatively correlated with the number of CAG repeat units, but only part of the variation in onset age is explained by CAG repeat length. Ages at onset and CAG repeat lengths of 136 MJD patients from 23 kindreds of Portuguese descent were analyzed, to determine whether familial factors independent of CAG repeat length modulate age at onset of MJD. Correlation among sibs for onset age adjusted for CAG repeat length was .43, which indicates that an environmental or genetic factor common to sibs influences onset age. Positive correlations were also observed for avuncular (r = .22) and first-cousin pairs (r = .28), which supports the hypothesis that a genetic factor is influencing age at onset. Commingling analysis of onset ages adjusted for CAG repeat length identified three distributions in this population of affected individuals. Further studies of a much larger sample are needed to determine whether these distributions represent the influence of a genetic or environmental factor. 相似文献
38.
Paula A. Belinky Segula Masaphy Dan Levanon Yitzhak Hadar Carlos G. Dosoretz 《Applied microbiology and biotechnology》1994,40(5):629-633
The effect of nitrogen and fatty-acid-rich substrates on the production of 1-octen-3-ol by the edible fungus Pleurotus pulmonarius, during growth in both shaken flask and fermentor cultures, and in-vitro, in post-harvested mycelium, was studied. Addition of soybean flour and soybean oil to the growth medium enhanced 1-octen-3-ol production about sevenfold and doubled the fungal biomass, as compared to that obtained from P. pulmonarius cultured on a defined synthetic medium. A clear relationship between the production of 1-octen-3-ol and lipoxygenase activity was found during the growth of mushroom pellets. The highest in-vitro generation of 1-octen-3-ol was obtained upon addition of exogenous linoleic acid and pure O2 to pellets grown with soybean fluor and soybean oil. This generation was even higher than that of fruiting bodies exposed to the same conditions. These results suggest that lipoxygenase activity and, subsequently, 1-octen-3-ol biosynthesis in P. pulmonarius are enhanced by the presence of substrates containing fatty acids in the growth medium.
Correspondence to: D. Levanon 相似文献
39.
Expression of galectins on microvessel endothelial cells and their involvement in tumour cell adhesion 总被引:5,自引:0,他引:5
Reuben Lotan Paula N. Belloni Robert J. Tressler Dafna Lotan Xiao-Chun Xu Garth L. Nicolson 《Glycoconjugate journal》1994,11(5):462-468
Lactoside-binding lectins (galectins) with molecular weights of about 14.5 kDa (galectin-1) and 29–35 kDa (galectin-3) bind preferentially to polylactosaminoglycan-containing glycoconjugates and have been found on the surface of tumour cells and implicated in cell-cell and cell-extracellular matrix adhesion and metastasis. We have demonstrated by immunoblotting that both galectin-1 and galectin-3 are present in extracts of endothelial cells cultured from bovine aorta, rat lung, mouse lung and mouse brain microvessels, whereas mouse hepatic sinusoidal endothelial cells expressed primarily galectin-1. These galectins were also localized by indirect immunofluorescent labelling on the surface of the different endothelial cells in culture and by immunohistochemical staining in human tissuesin vivo. Anti-galectin-1 antibodies inhibited the adhesion of liver-preferring murine RAW117-H10 large-cell lymphoma cells to hepatic sinusoidal endothelial cells or lung microvessel endothelial cellsin vitro. The data indicate that galectin-1 is expressed on the extracellular surface of endothelial cells and can mediate in part the adhesion of RAW117-H10 cells to liver microvessel endothelial cells. 相似文献
40.
Protein Kinase C Activation Attenuates N-Methyl-d-Aspartate-Induced Increases in Intracellular Calcium in Cerebellar Granule Cells 总被引:1,自引:0,他引:1
Lawrence D. Snell Karen R. lorio Boris Tabakoff Paula L. Hoffman 《Journal of neurochemistry》1994,62(5):1783-1789
Abstract: Activation of the N-methyl-d -aspartate (NMDA) subtype of glutamate receptor increases levels of intracellular calcium and can lead to stimulation of protein kinase C activity. Several reports have demonstrated that stimulation of protein kinase C can, in turn, increase electrophysiological responses to NMDA in certain cells or in oocytes expressing certain NMDA receptor subunits. In the present study, the effects of protein kinase C activation on NMDA receptor-mediated increases in intracellular Ca2+ levels were investigated in primary cultures of rat cerebellar granule cells using fura-2 fluorescence spectroscopy. Pretreatment of the cells with the protein kinase C activator phorbol 12-myristate 13-acetate (PMA), but not the inactive analogue 4α-phorbol 12-myristate 13-acetate, inhibited NMDA-induced increases in intracellular Ca2+ levels. Coincubation of cells with PMA and the kinase inhibitor staurosporine or calphostin C blocked the PMA effect. The potency of NMDA was reduced twofold, and the potency of the NMDA receptor coagonist, glycine, to enhance the response to NMDA was decreased fourfold by pretreatment of cells with PMA. The effect on glycine was mimicked by pretreatment with okadaic acid, a protein phosphatase inhibitor. PMA treatment did not significantly alter Mg2+ inhibition of the NMDA response but decreased the potency of the competitive antagonist CGS-19755. These data suggest that, in cerebellar granule cells, the function of the NMDA receptor may be subject to feedback inhibition by protein kinase C stimulation. Under physiological conditions, this inhibition may result from a decreased effectiveness of the endogenous coagonists, glutamate and glycine. 相似文献