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111.
T Dalton 《Experientia》1976,32(11):1421-1423
5-Hydroxytryptamine creatinine sulphate loses its biological activity when maintained at room temperature. The loss of 5-HT activity (in stimulating sodium transport across frog skin) is greater than the loss of creatinine sulphate activity (inhibition of sodium transport). 相似文献
112.
The hyperthermic effect of a bacterial pyrogen has been studied in rabbits pretreated or not with p-chlorophenylalanine or 5, 6-dihydroxytryptamine. The results obtained indicate that a selective reduction of cerebral 5-hydroxytryptamine levels by these drugs do not significantly affect pyrogen hypertermia. 相似文献
113.
Patricia M. Kralik Beng T. Ho H. R. Matthews 《Cellular and molecular life sciences : CMLS》1976,32(6):723-725
Summary
9 (10 mg/kg, i.p.) administered to mice immediately after withdrawal from a 3-day exposure to ethanol vapor was found to intensify withdrawal reactions. No effect was seen when
9 was administered chronically during the exposure to ethanol. 相似文献
114.
海南岛万泉河口沉积环境演变 总被引:11,自引:0,他引:11
根据对柱样沉积物210Pb定年及有机碳、硫和有机碳同位素含量分析, 研究万泉河口沉积环境演变. 硫和δ13C均自19世纪初期开始持续减少, 硫从1.92%逐渐减少到0.36%, δ13C从8722;20.63‰减少到8722;23.64‰. C/S比在20世纪之前一直很稳定, 处于0.47~0.80之间, 有机碳与硫呈正相关; 在此之后, C/S比急剧增加, 至表层为3.94, 硫的含量与有机碳的增加没有相关关系. 结果表明在19世纪之前万泉河口尚为开阔的海湾, 处于正常海洋环境,未形成被沙坝围封的泻湖, 海水能够直接出入. 19世纪初期开始, 随着玉带滩沙坝向北发育, 河口逐渐被围拦成泻湖型, 进入的海水量逐渐减少; 在19与20世纪之交, 水体已开始明显淡化, 发展成为今天近乎淡水的泻湖. 相似文献
115.
T. Matsuoka T. Nishizaki Y. Ikeuchi Y. Okada K. Sumino 《Cellular and molecular life sciences : CMLS》1997,53(3):233-236
Effects of serotonin (5-HT) on cerebral cortical neurons were examined by patch clamp techniques. 5-HT produced a variety
of responses such as outward (19/73 patches/neurons), slow inward (15/73 patches/neurons), fast inward (8/73 patches/neurons),
and mixed currents (initially fast inward deflection followed by an outward response: 2/73 patches/neurons), with a latency
of 12 sec, 15 sec, 0 sec, and 0 sec respectively, at a holding potential of −60 mV in whole-cell patches. The fast inward
currents were again evoked by a selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide hydrochloride (CPBG). In the
cell-attached patch clamp configuration, 5-HT inside the patch pipette elicited single channel currents with slope conductances
of 42 pS and 132 pS (4/42 patches/neurons). CPBG inside the patch pipette evoked inward single channel currents with a lower
slope conductance of 41 pS (3/23 patches/neurons). In contrast, application of 5-HT or a 5-HT2 receptor agonist, α-methyl-5-hydroxytryptamine-maleate, outside the patch pipette induced outward single channel currents with a major slope
conductance of 140 pS (8/30 patches/neurons) or 135 pS (6/20 patches/neurons), respectively. These results indicate that the
outward and fast inward currents may be mediated respectively by the 5-HT2 receptor, which is coupled to a G-protein, and by the 5-HT3 receptor, which contains the non-selective cation channel, and that the mixed type may be caused by both the 5-HT2 and 5-HT3 receptors.
Received 27 September 1996; received after revision 4 November 1996; accepted 7 November 1996 相似文献
116.
J. W. M. Lagerberg J. VanSteveninck T. M. A. R. Dubbelman 《Cellular and molecular life sciences : CMLS》1997,53(3):257-262
The fluorescent dye Merocyanine 540 (MC540) is often used as a probe to monitor the molecular packing of phospholipids in
the outer leaflet of biomembranes. In a previous study we showed that the increased staining of erythrocytes with a perturbed
membrane structure was mainly due to an increase in the fluorescence yield of cell-bound MC540, rather than to an increase
of the number of bound molecules. Erythrocytes and ghosts exposed to continuous fluxes of H2O2 exhibited pronounced lipid peroxidation. Further, red blood cells subjected to this form of oxidative stress also showed
increased staining with MC540. It appeared that this was caused by a strong increase in binding of MC540, together with a
slight red shift of the fluorescence emission maximum and a small increase in the fluorescence yield of bound MC540. The changed
MC540 binding characteristics were not observed when lipid peroxidation was suppressed by the presence of the antioxidant
BHT in the incubation medium. However, open ghosts exposed to H2O2 showed no increase of MC540 binding, excluding a direct involvement of lipid peroxidation. Measurement of fluorescence emission
spectra and gel filtration studies showed that MC540 can bind to H2O2-exposed hemoglobin. Experiments with erythrocytes lysed in hypotonic medium after exposure to H2O2 revealed that peroxidation of lipids with H2O2 induced a non-specific permeabilization of the plasma membrane to MC540, thereby allowing MC540 to bind to the oxidatively
denatured, more hydrophobic hemoglobin. These results indicate that conclusions about packing of phospholipids in the outer
leaflet of the membrane based on increased MC540-staining should be drawn with care.
Received 27 September 1996; received after revision 5 November 1996; accepted 27 November 1996 相似文献
117.
118.
Antioxidant survey to assess antagonism to redox stress using a prokaryotic and an eukaryotic system
H. Baker B. DeAngelis O. Frank M. Khalil S. H. Hutner E. R. Baker 《Cellular and molecular life sciences : CMLS》1996,52(6):597-599
Using a prokaryote (Escherichia coli) and a metazoa-resembling eukaryote (Ochromonas danica), we surveyed antioxidants which might overcome redox stress imposed by menadione sodium bisulphite (MD) and buthionine sulphoximine (BSO). BSO oxidant stress was evident only inO. danica; MD oxidant stress was evident in both organisms. Glutathione, its precursors, e.g. cysteine, homocysteine, and 2-oxo-4-thiazolidine carboxylic acid, and red blood cells, emerged as prime antioxidants for relieving BSO and MD oxidant stress. BSO and MD oxidant activity and antioxidant-annulling effect inO. danica were judged comparable to those found in animal cells whereas the resultsE. coli were not entirely equivalent. TheO. danica system emerged as a practical, rapid, and useful system for pinpointing oxidant stressors and antioxidants, and shows promise for studies with mammalian systems. 相似文献
119.
The maximum consumption of the larvae of the pest and vector mosquitoCulex quinquefasciatus by the predatory mosquitoCulex (Lutzia) raptor was studied at various instars of both the predator and the prey. The prey preferences of the predator when given lavae of different instars were also investigated. The IVth instar of the predator consumed the maximum number of Ist instar and the maximum biomass of IVth instar larvae of the prey. Instars I and II of the predator preferred the Ist of the prey; instars III and IV of the predator preferred instars II and III of the prey respectively.The predator consumed an average of 157.1 larvae during its whole larval period, when each instar of the predator was given its preferred instar of the prey. 相似文献
120.
城市定位与城镇群建设 总被引:2,自引:0,他引:2
城市是一个国家和民族对外开放的窗口、商品国际交换的平台,它决定着整个国家和地区的竞争力。文章对廊坊市城市发展的现状和廊坊市城镇群建设战略进行了论述,希望对我国其他城市的发展有一定的参考作用。 相似文献