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31.
本文对高原冻伤中血液循环障碍作形态计量,旨在探讨血循环障碍在冻伤过程中的变化及高原冻伤发病机理中所起的作用。实验选用Wistar雄性大鼠40只,随机分为平原冻伤组、急性低氧冻伤组和低氧习服冻伤组。习服组动物于低压舱内模拟海拔6000m缺氧每日4h,连续两周。其余动物常规饲养。习服期满次日习服组与低氧组一同进入舱内模拟海拔6000m低氧4h,再行冷冻。冻后继续低氧4h。冻后48h取材。对各组动物冻后48h冻肢皮下血管的病变作图象分析。结果发现,平原组血管淤滞、血栓绝对数及其百分比均为最低,习服组最高,低氧组居中。但低氧组与平原组的血栓/淤滞百分比无明显差别。骨骼肌坏死的面积百分比习服组显著高于低氧组与平原组,而后两组间无差别。血栓/淤滞百分比与骨骼肌坏死面积百分比之间的有高度相关关系。冻融是直接引起血管内皮损伤的原发因素,局部血液循环障碍是造成严重的继发损伤的主要原因。 相似文献
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核糖核酸(RNA)与稀土铽离子在pH5.0~6.5条件下能形成具有较强荧光的络合物,其激发峰在288nm处,发射峰为494nm及545nm处.RNA在0.1~10mg/L范围内与其荧光强度呈线性关系,其检出限为6.0×10 ̄(-8)mol/L.腺苷酸,尿苷酸,胞苷酸对RNA的干扰比较小,因此可在其存在下选择性地测定RNA. 相似文献
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Cell signaling and heat shock protein expression 总被引:5,自引:0,他引:5
Exposure of cells and organs to heat shock is associated with numerous changes in various cellular metabolic parameters and overexpression of proteins collectively known as heat shock proteins (HSP). In this communication we review the cell-signaling events that are altered in response to heat shock as they relate to the subsequent induction of HSP 70 kd (HSP-70) expression. We also review the mechanisms by which HSP-70 is involved in conferring cytoprotective effects. The possibility of altering HSP expression through manipulations of the cell-signal process has clinical importance.The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of the Army or Department of Defense. 相似文献
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The role of context on alpha-helix stabilization: host-guest analysis in a mixed background peptide model. 总被引:1,自引:1,他引:0 下载免费PDF全文
J. Yang E. J. Spek Y. Gong H. Zhou N. R. Kallenbach 《Protein science : a publication of the Protein Society》1997,6(6):1264-1272
The helix content of a series of peptides containing single substitutions of the 20 natural amino acids in a new designed host sequence, succinyl-YSEEEEKAKKAXAEEAEKKKK-NH2, has been determined using CD spectroscopy. This host is related to one previously studied, in which triple amino acid substitutions were introduced into a background of Glu-Lys blocks completely lacking alanine. The resulting free energies show that only Ala and Glu- prove to be helix stabilizing, while all other side chains are neutral or destabilizing. This agrees with results from studies of alanine-rich peptide modela, but not the previous Glu-Lys block oligomers in which Leu and Met also stabilize helix. The helix propensity scale derived from the previous block oligomers correlated well with the frequencies of occurrence of different side chains in helical sequences of proteins, whereas the values from the present series do not. The role of context in determining scales of helix propensity values is discussed, and the ability of algorithms designed to predict helix structure from sequence is compared. 相似文献
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Gong CS Chen LF Flickinger MC Chiang LC Tsao GT 《Applied and environmental microbiology》1981,41(2):430-436
d-Xylulose, an intermediate of d-xylose catabolism, was observed to be fermentable to ethanol and carbon dioxide in a yield of greater than 80% by yeasts (including industrial bakers' yeast) under fermentative conditions. This conversion appears to be carried out by many yeasts known for d-glucose fermentation. In some yeasts, xylitol, in addition to ethanol, was produced from d-xylulose. Fermenting yeasts are also able to produce ethanol from d-xylose when d-xylose isomerizing enzyme is present. The results indicate that ethanol could be produced from d-xylose in a yield of greater than 80% by a two-step process. First, d-xylose is converted to d-xylulose by xylose isomerase. d-Xylulose is then fermented to ethanol by yeasts. 相似文献
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用改进的固相磷酰三酯法合成了oligo-d(G-C)_3。以氩离子激光为激发光源,波长488nm.,在室温条件下,分别测定了纯化后的oligo-d(G-C)_3和其组分单体5’-dGMP和5’-dCMP的激光喇曼谱。观察到被测定的物质在300-2500cm~(-1)频率区间,各自都有其特征的谱形和喇曼峰。5’-dGMP和5’-dCMP谱中大多数特征峰在寡聚体的谱中消失,而在oligo-d(G-C)_3谱中出现了几处新的喇曼峰。经查证,峰832,851和899cm~(-1)系糖-磷酸主链的特征喇曼峰,另外几处峰与DNA的构象有关。实验结果表明oligo-d(G-C)_3在水溶液中(室温)主要以B-构象存在。 相似文献
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