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Hypotonicity-induced anion permeability changes were investigated but not detected in immortalised (RBE4) rat brain endothelial cells using iodide efflux measurements. Large, rapid increases were however observed in primary cultured cells. Both cell types were reinvestigated following culture in a common growth factor-depleted medium. Responses were still undetectable in the immortalised RBE4 cells. Reduced responses were observed in the primary cultured cells that also showed altered morphology and decreased activity of another transporter, P-glycoprotein. Thus both immortalisation and different culture conditions may alter functional expression in these cells of transporters involved in hypotonicity-induced anion permeability changes. 相似文献
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B Wiemann GY Van DM Danilenko Q Yan C Matheson L Munyakazi S Ogenstad CO Starnes 《Canadian Metallurgical Quarterly》1998,149(2):455-463
Experimental autoimmune encephalomyelitis (EAE) is a term given to describe a collection of animal models representing the human disease multiple sclerosis (MS). Although not fully understood, the involvement of cytokines and the immune system in either EAE or human MS is well established. Past efforts have shown that inhibition of proinflammatory cytokines tumor necrosis factor (TNF-alpha) or interleukin-1 (IL-1) result in amelioration of acute EAE in Lewis rats. The present study examined this model for the effect of concomitant inhibition of both TNF-alpha and IL-1, which resulted in a modest but significant therapeutic effect that was superior to inhibition of either single agent alone with respect to four of the five variables used to follow the progression of disease in this model, i.e., clinical severity, frequency of disease, loss of body weight, and day of onset. These results are in accordance with the idea that combination treatments are likely to prove superior to single agent therapy in the treatment of autoimmune inflammatory disease. 相似文献
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Dendrites of pyramidal neurons from embryonic rat hippocampus are investigated in culture using a voltage-sensitive fluorescent dye. The electrical response to somatic stimulation is observed as a time-resolved map with a resolution of 0.9 microm at a time constant of 0.4 ms without signal averaging. The data are interpreted in terms of a tapering cable with Hodgkin-Huxley parametrization. The spread of short hyperpolarizing transients is damped by capacitive shunting. The invasion of an action potential is boosted by voltage-gated conductances of a low density. No irregularity is observed at a bifurcation. The passive cable parameters of internal resistance and membrane resistance at resting voltage are Ri = 300 omega cm and Rm = 40 (k)omega cm2 respectively, at a maximum sodium conductance of approximately 4.4 mS/cm2. The electrotonic length constant and the dynamic length constant at 1 kHz are 580 and 90 microm respectively. These results are compatible with electrophysiological data of dendrites in slices of adult hippocampus and with optical data of narrow processes of leech neurons in culture. The functional implications of boosting an action potential by voltage-gated channels of low density are considered. 相似文献
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Space diversity and angle diversity experimental data have been collected over a three year period, using 64 quadrature amplitude modulation (QAM) radios, on the terrestrial microwave radio hop between Salton and Brawley in southern California. Both measured data and simulations have shown that the performance of angle diversity systems depends on the direction of transmission as well as the polarization of the signal. While this may also be true for space diversity, the effects of a finite spatial correlation length and a small signal-to-noise ratio significantly reduce the sensitivity of space diversity to the direction of propagation. Additionally, the performance of angle diversity is shown to depend upon the method used to implement angle diversity 相似文献
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