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81.
Márcia Camargo-De-Morais Marta De Freitas Angela G. De Mattos Nádia Schröder Ana C. Zilles Carla S. F. Lisboa Nice Arteni Armando Barlem Rejane Schierholt Guilherme Zwetsch Carlos A. B. Souza Regina Pessoa-Pureur Carlos A. Netto 《Neurochemical research》1996,21(5):595-602
Neurofilaments subunits (NF-H, NF-M, NF-L) and glial fibrillary acidic protein (GFAP) were investigated in the hippocampus
of rats after distinct periods of reperfusion (1 to 15 days) following 20 min of transient global forebrain ischemia in the
rat. In vitro [14Ca]leucine incorporation was not altered until 48 h after the ischemic insult, however concentration of intermediate filament
subunits significantly decreased in this period. Three days after the insult, leucine incorporation significantly increased
while the concentration NF-H, NF-M, and NF-L were still diminished after 15 days of reperfusion. In vitro incorporation of32P into NF-M and NF-L suffered immediately after ischemia, but returned to control values after two days of reperfusion. GFAP
levels decreased immediately after ischemia but quickly recovered and significantly peaked from 7 to 10 days after the insult.
These results suggest that transient ischemia followed by reperfusion causes proteolysis of intermediate filaments in the
hippocampus, and that proteolysis could be facilitated by diminished phosphorylation levels of NF-M and NF-L. 相似文献
82.
Maria Claudia Gonzalez Deniselle Susana L. Gonzalez Gerardo G. Piroli Analia E. Lima Alejandro F. De Nicola 《Cellular and molecular neurobiology》1996,16(1):61-72
Summary 1. Wobbler mice suffer an autosomal recessive mutation producing severe motoneuron degeneration and dense astrogliosis, with
increased levels of glial fibrillary acidic protein (GFAP) in the spinal cord and brain stem. They have been considered animal
models of amyotrophic lateral sclerosis and infantile spinal muscular atrophy.
2. Using Wobbler mice and normal littermates, we investigated the effects of the membrane-active steroid Lazaroid U-74389F
on the number of GFAP-expressing astrocytes and glucocorticoid receptors (GR). Lazaroids are inhibitors of oxygen radical-induced
lipid peroxidation, and proved beneficial in cases of CNS injury and ischemia.
3. Four days after pellet implantation of U-74389F into Wobbler mice, hyperplasia and hypertophy of GFAP-expressing astrocytes
were apparent in the spinal cord ventral and dorsal horn, areas showing already intense astrogliosis in untreated Wobbler
mice. In control mice, U-74389F also produced astrocyte hyperplasia and hypertophy in the dorsal horn and hyperplasia in the
ventral-lateral funiculi of the cord.
4. Givenin vivo U-74389F did not change GR in spinal cord of Wobbler or control mice, in line with the concept that it is active in membranes
but does not bind to GR. Besides, U-74390F did not compete for [3H]dexamethasone binding when addedin vitro.
5. The results suggest that stimulation of proliferation and size of GFAP-expressing astrocytes by U-74389F may be a novel
mechanism of action of this compound. The Wobbler mouse may be a valuable animal model for further pharmacological testing
of glucocorticoid and nonglucocorticoid steroids in neurodegenerative diseases. 相似文献
83.
Ana Maria Landeira-Fernandez Maricilia S. Costa Leopolde de Meis 《Bioscience reports》1996,16(6):439-451
Vesicles derived from maize roots retain a membrane bound H+-ATPase that is able to pump H+ at the expense of ATP hydrolysis. In this work it is shown that heparin, fucose-branched chondroitin sulfate and dextran sulfate 8000 promote a shift of the H+-ATPase optimum pH from 6.0 to 7.0. This shift is a result of a dual effect of the sulfated polysaccharides, inhibition at pH 6.0 and activation at pH 7.O. At pH 6.0 dextran 8000 promotes an increase of the apparent Km for ATP from 0.28 to 0.95 mM and a decrease of the Vmax from 14.5 to 7.1 mol Pi/mg · 30 min–1. At pH 7.0 dextran 8000 promotes an increase in Vmax from 6.7 to 11.7 mol Pi/mg · 30 min–1. In the presence of lysophosphatidylcholine the inhibitory effect of the sulfated polysaccharides observed at pH 6.0 was not altered but the activation of pH 7.0 decreased. It was found that in the presence of sulfated polysaccharides the ATPase became highly sensitive to K+ and Na+. Both the inhibition at pH 6.0 and the activation promoted by the polysaccharide were antagonized by monovalent cations (K+>Na+Li+).Abbreviations Mops
4-morpholinopropanesulfonic acid
- EDTA
ethylenediaminetetraacetic acid
- ACMA
9-amino-6-chloro-2-methoxyacridine
- FCCP
carbonyl cyanide p(trifluoromethoxy)-phenylhyrazone 相似文献
84.
Jörg Dreessen Claudia Lutum Beat W. Schäfer Claus W. Heizmann Thomas Knöpfel 《Cell calcium》1996,19(6):527-533
We investigated whether the expression of human α-parvalbumin affects depolarization-induced elevations of the cytosolic free calcium concentration ([Ca2+]i) in human neuroblastoma SKNBE2 cells. A full length human parvalbumin cDNA was cloned by PCR from human cerebellum and transiently transfected into SKNBE2 cells. Immunofluorescence staining using an antibody raised against parvalbumin revealed a transfection efficacy of about 14%. In parvalbumin-expressing SKNBE2 cells, parvalbumin concentration determined by quantitative Western blotting amounted to 0.42 mM.Transfected SKNBE2 cells were depolarized for 2 min by 50 mM K+. During this period, [Ca2+]i was monitored by video microfluorimetry using the Ca2+ indicator Fura-2. In a fraction of cells, depolarization induced a transient elevation in [Ca2+]i The size of this elevation was compared with the immunofluorimetrically determined expression of parvalbumin on a cell-to-cell basis. Cells with a significant parvalbumin immunofluorescence responded to depolarization with smaller elevations in [Ca2+]i than non-parvalbumin-expressing cells. Resting [Ca 2+], did not differ between parvalbumin-expressing and control cells. These observations indicate that large depolarization-induced transient elevations of [Ca2+]i in neuroblastoma cells can be suppressed by parvalbumin. 相似文献
85.
Results are presented on the phytoplankton species compositionand abundance from bottle samples collected in September 1989near the confluence of the Brazil and Malvinas currents offArgentina. The phytoplankton assemblages were dominated by diatomsand dinoflagellates. A surface diatom bloom was found alongthe west side of the Brazil Current, and was dominated by Thalassiosiradelicatula Ostenfeld emend. Hasle (cell numbers up to 5.5 x105 cells 11) The bloom was associated with strong temperaturegradients separating Brazil and Malvinas waters, and with thepresence of a cyclonic eddy near the confluence of the currents.These features were detected in satellite imagery coincidentwith the in situ sampling dates. 相似文献
86.
Ana Cristina Gomes da Cunha Manuel Fernandes Ferreira 《Plant Cell, Tissue and Organ Culture》1996,47(1):1-8
The effects of plant growth regulators (PGR) on calli induction, morphogenesis and somatic embryogenesis of flax were studied. The organogenic and callus formation capacity were assessed for different types of source explants. Root and shoot explants were equally good material for calli production but the former produced calli without shoot regeneration capacity. Under the experimental conditions tested, 2,4-dichlorophenoxyacetic acid (2,4-D) + zeatin was the most efficient PGR combination on calli induction and biomass production. The calli were green but with no rhizogenic capacity. In contrast, and at similar concentrations, indole-3-butyric acid (IBA) + kinetin induced white or pale green friable calli with a good root regeneration capacity (60%). A factorial experiment with different combinations of 2,4-D + zeatin + gibberellic acid (GA3) levels revealed that the direction of explant differentiation was determined by specific PGR interactions and concentrations. The results from these experiments revealed that the morphogenetic pathway (shoot versus root differentiation) can be manipulated on flax explants by raising the 2,4-D level from 0.05 to 3.2 mg l?1 in the induction medium. The induction and development of somatic embryos from flax explants was possible in a range of 2,4-D + zeatin concentrations surrounding 0.4 mg l?1 2,4-D and 1.6 mg l?1 zeatin, the most efficient growth regulator combination. 相似文献
87.
A strain ofFusarium solani sensu Snyder & Hansen invaded the eggs of the insectPanstrongylus geniculatus in a vivarium. None of the invaded eggs hatched. To establish experimentally the pathogenicity of thisFusarium species against the eggs ofP. geniculatus, the fungus and the eggs were incubated together under different relative humidities and temperatures. At 64% relative humidity and 26 °C, the fungus grew well colonizing and penetrating all of the chorions.Three embryos died and were also colonized byF. solani. Only 4 nymphs hatched and survived to day 20. It is concluded that the isolate ofF. solani was capable of colonizing and invading the chorion of the eggs under certain humidity and temperature conditions and cause the death of the embryos. 相似文献
88.
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 下载免费PDF全文
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
89.
Ana María Planchuelo 《Brittonia》1996,48(2):263-265
Lupinus rubriflorus Planchuelo, from Rio Grande do Sul, Brazil, is described and illustrated. This species is related toL. bracteolaris s.l. differing in pubescence, stipules, and floral characters. 相似文献
90.
Sandra Irene Pitta-Alvarez Ana María Giulietti 《In vitro cellular & developmental biology. Plant》1995,31(4):215-220
Summary
Brugmansia candida hairy roots, obtained by infection withAgrobacterium rhizogenes LBA 9402, exhibit, after subculturing in liquid media, a tendency towards dedifferentiation. It has been found that the following
strategies can be applied to inhibit this dedifferentiation and preserve normal root morphology: (a) lowering both the mineral
and sucrose concentration in the media employed so as to diminish osmotic stress (a condition to which these roots appear
to be particularly susceptible); (b) employing antiauxins in appropriate concentrations; and (c) maintaining the hairy roots
on solid media prior to use in production processes in liquid media. The first strategy suggested does not favor alkaloid
productivity, but in this case a two-step method could be attempted: biomass with normal root morphology could be obtained
in a first stage using low sucrose concentrations, and in a second stage, sucrose could be increased in order to achieve higher
productivity. In all the clones ofB. candida obtained, alkaloid production was biased towards scopolamine. 相似文献