Caffeine actions on currents induced by calcium-overload in Purkinje fibers

The ionic events underlying the changes induced by caffeine in calcium-overloaded Purkinje fibers were studied by means of a voltage-clamp technique. The following results were obtained. In fibers exposed to strophanthidin (5 X 10(-7) M), a depolarizing clamp of suitable magnitude or duration is followed by an oscillatory current (Ios) often superimposed on a decaying inward tail current (the "tail current"). Caffeine (9 mM) abolishes Ios and increases the tail current. Caffeine has similar actions when calcium overload is induced by increasing [Ca]0 or decreasing [Na]0. The magnitude of the tail current is reduced by decreasing [Ca]0. The tail current appears with repolarizations to -40 mV or more negative values as Ios appears in the absence of caffeine. As with Ios the tail current can be triggered twice (during and after a test clamp of suitable characteristics), becomes more inward with repeated clamps and becomes larger with larger or longer conditioning clamps. During the recovery from caffeine exposure, the tail current decreases gradually as Ios returns progressively. It is concluded that both Ios and tail current are caused by calcium overload but are affected in opposite direction by caffeine, apparently because caffeine decreases the calcium overload in the sarcoplasmic reticulum (abolition of Ios) and increases the calcium to be extruded from the sarcoplasm (increase in the tail current).     

Methods of detecting mature human Ia-like antigen and their metabolic precursors

Ia antigens were shown to be present in the cell almost exclusively as mature alpha beta dimers which split into separate alpha and beta chains after boiling in SDS. In contrast metabolically labelling the cells with [35S]methionine resulted in only free alpha and beta chains being labelled. It is concluded that this widely used type of labelling, although useful for studying intermediate synthesis, should not be used for labelling mature cell surface molecules.     

Interaction of immunoglobulin with actin

Actin can form specific, direct associations with immunoglobulin resulting in soluble complexes or cross-linked matrices. This interaction can be detected by four in vitro assays using purified components: (1) actin enhances the cytophilic activity of guinea pig IgG2; (2) in solutions of low ionic strength, actin and IgG2 co-precipitate: (3) soluble complexes exist in 0.1 M KCl as revealed by the displacement of actin from its expected sedimentation pattern in a gradient of sucrose when in the presence of IgG 1, IgG2, or IgM; (4) immunoglobulin (IgG1, IgG2, BGG)‡: increases the viscosity of F-actin solutions, presumably by crosslinking F-actin filaments. These data suggest that direct interaction of a cytoskeletal protein with a cell surface receptor is possible.     

β Chain deficiency in three patients with dysfunctional C8 molecules

Structural and functional studies were performed on a dysfunctional C8 molecule present in the serum of two siblings and an unrelated individual. The C8 in these three sera exhibited a pattern of partial immunologic identity with C8 in normal serum but was devoid of functional activity. The C8 was immunoprecipitated from the three sera and from a control serum with an antihuman C8 antiserum and analyzed by SDS-PAGE using highly purified human C8 as a reference. A selective absence of a band of 62,000 mol. wt was observed in the immunoprecipitates from the sera containing dysfunctional C8. Experiments performed with the purified α-γ and γ subunits showed that the hemolytic activity of the C8 deficient sera could be reconstituted by the addition of the β chain but not the α-γ dimer. Binding of the dysfunctional C8 to C$\text{567}$ was excluded by the following observations: (1) EAC 1–7 treated with the C8 deficient sera and then washed could not be lysed after the addition of the β subunit and C9; and (2) the abnormal molecules did not interfere with the consumption of normal C8 by the soluble complex SC5b-7.     

Electrical Analysis of Fresh,Excised Human Skin: A Comparison with Frozen Skin

Samples of human allograft skin prepared without freezing ("fresh skin) were found to have electrical and sodium ion transport properties which differed only slightly from those of skin which had been similarly treated but stored frozen (frozen skin). The fresh skin samples were less permeable to sodium ions during passive diffusion and less conductive than frozen skin at low current levels. They were more permselective for sodium versus chloride during constant-current iontophoresis and showed slightly more asymmetry in their current–voltage properties. Overall, the electrical behavior of the two tissues was similar enough to support the use of frozen tissue in iontophoresis studies. However, caution should be exercised when considering the use of frozen skin for applications, such as those based on electroosmosis, where the observed differences could have a major impact on the results.     

甘油氯化钠注射液降低颅内压52例临床观察

目的：评价甘油氯化钠注射液降低颅内压的临床效果以及观察有无副作用。方法：对52例颅内压增高患者用甘油氯化钠降低颅内压,与44例用甘油果糖及32例用甘露醇降低颅内压进行比较,通过颅内压监测仪观察效果及副作用。结果：注射甘油氯化钠后1.05±0.23 h颅内压开始下降,2.32±0.36 h作用达到高峰,持续5.25±1.42 h;无反跳现象,对肾功能影响小,无溶血现象。结论：甘油氯化钠注射液适用于亚急性颅内压增高、高龄患者及肾功能有损害者。     

异丙酚乳剂用于腹腔镜胆囊切除术40例体会

目的：探讨异丙酚乳剂用于腹腔镜胆囊切除术麻醉中的优缺点。方法：１００例施行腹腔镜胆囊切除术患者,随机分为异丙酚组４０例,硫喷妥钠组６０例。观察记录两组患者手术前、给药后１ｍｉｎ、气管插管时、插管后５ｍｉｎ、ＣＯ２气腹后３ｍｉｎ血流动力学各参数并观察停药后患者苏醒情况及麻醉副作用等。结果：异丙酚比硫喷妥钠更适用于腹腔镜胆囊切除术麻醉,但也要注意异丙酚对呼吸、循环系统功能的抑制作用。     

晶氧和碳酸氢钠改善第二产程母血酸碱平衡

对９９ 例经阴道分娩的产妇于第二产程开始时给予鼻导管吸氧,静脉滴注碳酸氢钠、过氧化氢碳酸酰胺（ 晶氧） ,于第二产程始末两次采母桡动脉血行血气分析。结果显示：晶氧碳酸氢钠联用组（ Ⅰ组）于第二产程结束时其ｐＨ,ＢＥ,ＰＯ２ 及Ｏ２ｓａｔ均显著高于对照组（ Ⅲ组）（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） ,而ＰＯ２ 及Ｏ２ｓａｔ则无统计学差异;Ⅰ组与Ⅱ组ｐＨ,ＰＯ２ 及Ｏ２ｓａｔ 值于第二产程末较开始时显著升高（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） ,ＢＥ 在该产程始末无统计学差异;Ⅲ组上述４ 指标明显下降（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） 。各组间及组内比较ＰＣＯ２ 均无明显变化。提示第二产程中常规给予纠酸,吸氧内给氧能有效地改善产妇过度消耗所致的酸中毒和缺氧倾向。     

大鼠饮盐行为的个体发生的研究

研究不同性别的发育期大鼠饮盐行为的发生年龄及其与大鼠血浆醛固酮（ＡＬＤＯ）水平之间的关系,为研究高血压病提供基础资料。方法：用自控泵经口腔导管给大鼠灌注３％盐水,记录大鼠的饮盐水量。结果：禁盐能引起１３ｄ龄及１３ｄ龄以上大鼠的饮盐行为。而不能引出１３ｄ龄以下幼鼠的饮盐行为。幼鼠的饮盐行为无显著的性别差异。这与禁盐引起各年龄组大鼠的血浆ＡＬＤＯ水平都显著升高的现象不一致。结论：大鼠饮盐行为的发生与大鼠的年龄有关,与大鼠脑的发育,特别是与大鼠的饮盐中枢的发育及完善有关。