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41.
42.
Electrical coupling, without dye coupling, between mammalian astrocytes and oligodendrocytes in cell culture 总被引:3,自引:0,他引:3
Evidence of electrical and dye coupling between oligodendrocytes and astrocytes was sought in cultures of mouse spinal cord. Cell identity was verified using cell specific antigenic markers. In most experiments current was injected into oligodendrocytes while recording voltage in nearby astrocytes. Nine of 17 oligodendrocyte-astrocyte cell pairs showed weak electrical coupling; the average estimated coupling ratio was 0.03 +/- 0.06 (cf. 0.11 for oligodendrocyte-oligodendrocyte and 0.44 for astrocyte-astrocyte pairs; Kettenmann and Ransom: Glia, 1: 64-73, 1988). Application of 0.5 mM BaCl2 or 44.6 mM CsCl depolarized astrocytes and oligodendrocytes and was estimated to increase the coupling ratio between these cells 3-5-fold; these effects were rapid in onset and completely reversible. In 5 of 7 cases, oligodendrocyte-astrocyte pairs that appeared uncoupled in normal solution exhibited coupling during Ba++ or Cs+ exposure. The actions of these cations are believed to be mediated by blockade of glial K+ channels. Depolarization, per se, as induced by increasing [K+]o, did not increase coupling ratio. The fluorescent dye lucifer yellow (LY) was injected into 10 oligodendrocytes, 8 of which were electrically coupled to nearby astrocytes, and never passed into astrocytes in detectable quantities. Likewise, astrocytes injected with LY stained other astrocytes, but never oligodendrocytes. These findings document the presence of weak electrical coupling between astrocytes and oligodendrocytes, in the absence of dye coupling. Weak coupling of this sort could subserve metabolic interactions between these cells mediated by the passage of small but important molecules such as cyclic AMP, but would not allow strong electrical interactions. If such coupling among glial cells is widespread, it would constitute a "metabolic syncytium" that could serve to coordinate glial behavior. 相似文献
43.
伤寒史学研究成果简述 总被引:1,自引:0,他引:1
万晓刚 《Zhonghua yi shi za zhi (Beijing, China : 1980)》2000,30(4):211-214
建国以来有关伤寒史学的研究成果表现在相关人物、相关著作、相关事件、学术关系及阶段特征五个方面。前期研究成果 ,尚不足以充分展示伤寒学历史地位和现实意义 ,更无充分依据昭示其未来之发展方向 ,因而有必要继续深入开展伤寒史学研究 相似文献
44.
45.
The direct-current electroretinogram of seven pigmented and seven albino rabbits was recorded from both eyes for almost 4 h in response to repeated identical light stimuli. Stimulus duration was 10 s, light intensity was 6.8 × 102 lux, and the interval between the beginning of succeeding light stimuli was 3 min. The dark-adaptation period preceding light stimulation was 30 min for one of the eyes (unoccluded eye) and 150 min for the contralateral eye (occluded eye), which was patched during the first part (117 min) of the experiment. In pigmented animals, the b- and c-wave amplitudes of the unoccluded eye slowly increased during the first part of the experiment but not significantly during the second. The a-wave amplitude was not significantly changed. After removal of the cover, the a- and b-wave amplitudes of the occluded eye immediately attained but did not exceed the level of those in the unoccluded eye, irrespective of the light adaptation induced by the stimulus flashes previously presented to the unoccluded eye. (Control experiments on six pigmented rabbits confirmed that stimuli identical to those used in the main part of the study caused a light adaptation, since a decrease in a- and b-wave amplitudes occurred after the first light stimulus following an initial dark-adaptation period of 2 h for both eyes.) In albino rabbits, electroretinogram responses were clearly discernible in the occluded eye also during the first part of the experiment, probably because of transillumination of the head. In other respects, the results were essentially similar to those of pigmented animals. The observation that occluded eyes did not dark adapt better, as judged by the electroretinogram responses, than contralateral eyes given repeated light adaptive stimuli may indicate the presence of a mechanism for transfer of adaptation information between the eyes. 相似文献
46.
Ragnheiđur Bragadóttir Sven Jarkman 《Documenta ophthalmologica. Advances in ophthalmology》1995,90(3):291-303
The effects of the stable cyclic adenosine monophosphate analogue adenosine 3, 5-cyclic monophosphorothioate Sp-isomer (Sp-cAMPS) on the direct-current electroretinogram and the standing potential of the eye were studied. Corneal recordings were obtained from unilaterally vitrectomized albino rabbit eyes during alternating intravitreal perfusions with Sp-cAMPS and a control solution (Pharmacia eye irrigating solution). The contralateral eye was used as a control. To evaluate further the effects on the c-wave,in vivo intraretinal microelectrode measurements were made during simultaneous intravitreal perfusion of Sp-cAMPS and irrigating solution, respectively. Sp-cAMPS in concentrations of 1, 10 and 100µM was tested by corneal direct-current electroretinography. There was no significant effect on the a-wave amplitude. The b-wave amplitude was reversibly elevated at an Sp-cAMPS concentration of 100µM (p<0.01, n=7). The c-wave amplitude was reversibly elevated at a concentration of 10µM (p<0.001, n=8), and this effect was more pronounced at 100µM (p<0.001, n=7). The SP increased reversibly at a concentration of 100µM (p<0.001, n=7). Microelectrode recordings were performed with Sp-cAMPS at a concentration of 100µM. The recordings showed significant increases in both the transepithelial potential (p<0.01, n=3) and the slow PIII (p<0.01, n=3). The effects of Sp-cAMPS on the b-wave as well as on the two components of the c-wave suggest influences on both the inner retina and the retinal pigment epithelium of the rabbit eye.Abbreviations PHS
Pharmacia eye irrigating solution
- AMP
adenosine monophosphate
- Sp-cAMPS
adenosine 3, 5 - cyclic monophosphorothioate Sp-isomer 相似文献
47.
本文报告了0.1%敌鼠钠盐配制成的不同毒饵在旅客列车上对急性灭鼠毒饵拒食残存鼠的杀灭试验效果。采用间隔投饵饱和投药法,投毒14天便有效地杀灭了旅客列车上对急性灭鼠毒饵拒食残存鼠,粉迹法考核灭效达100%。敌鼠钠盐配制的毒饵适口性好,灭效高,现阶段列车灭鼠中,仍有较好的应用价值。 相似文献
48.
老年人的发病特点及预防 总被引:1,自引:0,他引:1
目的:通过对老年人健康状况的调查,总结老年人发病特点,提出预防和治疗措施,以期延长老年人的寿命,提高老年人生活质量。方法:将780铝调查对象集中於医院,按规范化标准作体格检查,并由主任医师作结论。结果:高血压、心脑血管道在病、白内障、前列腺疾患、肺气肿及糖尿病等为老年人常见病。结论:定期体检及提高基知务人璋减少和预防老年病的重要手段。 相似文献
49.
Arthurs BP Khalil MK Chagnon F Lindley SK Anderson DP Burnier M 《Ophthalmology》1999,106(12):2387-2390
OBJECTIVE: To present a patient with systemic lupus erythematosus who developed infarction and melting of the orbit secondary to her systemic disease. DESIGN: A case report. PARTICIPANT: A 61-year-old white woman with a 5-year history of systemic lupus erythematosus. METHODS: The patient presented with left orbital pain, limitation of extraocular movements, and a fistula from the ethmoid sinus to the upper eyelid. A detailed examination with computerized tomography, ultrasound, and a comprehensive medical evaluation with laboratory testing was performed. Histopathologic analysis with special stains of the orbital tissues was also performed. RESULTS: Histopathologic examination of the biopsy specimens revealed the features of an inflammatory process involving the orbit, similar to a panniculitis. These include a lymphocytic reaction with a predominance of plasma cells, vasculitis with occlusion, and thickening of the vessel walls, necrosis, and hyalinization of fat. CONCLUSION: This is a unique case in which infarction and melting of the entire orbital structures occurred in the presence of systemic lupus erythematosus. The underlying disease process is a lupus-related panniculitis. The authors stress that this is a very rare entity and that other diseases should be ruled out before entertaining this diagnosis. 相似文献
50.
Pentose shunt activity in developing chick retina and pigment epithelium was studied by measuring the rate of 14CO2 evolution from glucose selectively labelled in the C-1 and C-6 positions. In the retina, shunt activity declines from appreciable levels at stages 29–31 to minimal activity in the 2-week-old hatched chick. Overall retinal metabolism also declines up to stage 45, but dramatically increases again after hatching. Developing chick pigment epithelium has minimal shunt activity at all stages studied. In contrast, cultured chick pigment epithelium has appreciable shunt activity which is constant over a period of several weeks in culture. This appears to be a switch in biochemical differentiation which could form the basis at least in part for subsequent changes in cell types observed in cultured pigment epithelial cells byEguchi and Okada (1973). 相似文献