平行平板流动腔的合理设计和使用

高度远小于横向和纵向几何尺寸的平行平板流动腔，是当前用以体外研究细胞力学行为，特别是细胞粘附特性的主要工具之一。本文从目前常用的平行平板流动腔内流体定常流动时的切应力表达式出发，指出该切应力表达式仅适用于小雷诺数条件，由此确定平行平板流动腔几何尺寸的合理选择；通过对小孔入流和出流的平行平板流动腔流场的分析，指出该切应力表达式只在远离孔口边界一定距离，即达到均匀流动后成立。     

前交通动脉复合体区的显微解剖学研究

目的 研究前交通动脉复合体（antcrior communicating artery complex，ACoAC）及其毗邻结构的显微解剖特点，为该区域的手术提供显微解剖数据，方法在10例（20侧）成人头颅标本上，分别在不同的视角下对ACoAC及其发出的穿支动脉进行解剖观察；取出整脑后对ACoAC各部分直径、长度进行测量、拍照，所得数据用SPNSS10．0软件进行统计分析，结果10例（20侧半球）共有20支大脑前动脉。双侧ACA—A1段长度和直径比较未见显著性差异．ACA-A1段后下壁发出许多穿支血管。前交通动脉形态变异很多均发出穿支血管，分别供应下丘脑、视交叉、胼胝体膝部等。Hcubner回返动脉是ACoAC发出的最粗大的穿支血管，其起源、行程变异很大。ACoAC发出很多供应视交又及视神经的穿支血管．他们大多来自ACA—A1段。结论 ①双侧ACA-A1段发育多不对称，可能与前交通动脉瘤的发生有关。ACA—A1段均发出重要的穿支血管．手术时应仔细加以分辨、保护．．ACoA形态变异很大，但与ACA-A1段发育不良关东不大，②Heubner回返动脉起源和形态堑异很大。③OC和ON的血液供应有上、下两个起源。     

脊髓动脉的显微解剖

在手术显微镜下观察了37例婴幼儿脊髓前(正中)动脉和脊髓后(外侧)动脉的分支,其主要结果如下:婴幼儿脊髓平均长度为14.08±1.49cm,脊髓前(正中)动脉外侧分支平均为76.17±18.64支,中央动脉平均为169.78±25.51支.中央动脉分布到灰质前角、侧角和后角底部及邻近灰质的深层白质,而白质浅层和后角大部,则由软膜动脉网发出的穿支供应.此外.还讨论了与临床应用有关的问题.     

Atrial natriuretic factor (ANF) does not affect ion transport in human intestine but does in porcine intestine

The aim of this study was to test whether atrial natriuretic factor (ANF) exerts any effect on human intestinal ion transport, and the porcine intestine was used as a positive control of ANF's effects. Tissues from human proximal (n = 6) and distal (n = 6) colons, and from distal ileum (n = 6) were mounted in Ussing chambers, and short circuit current (I_sc) was measured subsequent to serosal application of ANF (10^--⁶ m), 8–Br-cyclic guanosine monophosphate (8–Br-cGMP) (10^--⁴ m), and theophylline (10^--² m). ANF did not affect I_sc whereas 8–Br-cGMP increased I_sc by 28 (8–53), 16 (3–36), and 16 (5–41) μA cm^-2 in the distal colon (DC), proximal colon (PC) and distal ileum (DI), respectively. Likewise, transepithelial potential difference (PD) became more negative by 5.0 (0.6–8.9), 2.5 (0.4–4.0) and 0.9 (0.3–2.3) mV in DC, PC, and DI, respectively, subsequent to addition of 8–Br-cGMP. I_sc and PD were further increased by theophylline. Additional radio-isotope flux studies in human colon revealed that ANF did not affect electroneutral sodium and chloride transport either. For comparison, ANF (10^--⁶ m) was administered to large intestinal tissues from young pigs in which ANF induced a significant increase in I_sc which was comparable to the 8–Br-cGMP response in humans. The porcine I_sc response was partly inhibited by chloride-free solution on the serosal side, by serosal application of bumetanide (10^--⁴ m) and BaCl₂ (10^--³ m), and mucosal application of the chloride-channel blocker diphenylamine-2–carboxylate (DPC) (10^--³ m). Mucosal amiloride (10^--⁵ m) pre-treatment reduced baseline I_sc but did not affect the porcine intestinal I_sc response to ANF. In vitro radio-autography demonstrated specific binding sites for ANF in porcine distal colon, whereas no apparent labelling was observed in human distal colon. These findings suggest that the lack of effect of ANF on sodium and chloride transport in human distal ileum and colon is probably due to lack of ANF receptors. In the porcine intestine, however, the I_S0 response induced by ANF seems to involve stimulation of electrogenic chloride secretion, whereas electrogenic sodium absorption seems unaffected.     

Dynamic relationship between EMG and torque at the human ankle: Variation with contraction level and modulation

Stochastic system identification techniques were used to determine the dynamic relationship between the electromyogram (EMG) and torque in the ankle muscles of normal human subjects. EMG and torque were recorded while subjects modulated ankle torque by tracking a computer-generated stochastic waveform. Nonparametric impulse response functions (IRFs) relating EMG to ankle torque were computed and parameterised by determining the parameters of the second-order system which provided the best least-squares fit. Two sets of experiments were carried out. In the first, the mean level of torque was varied from 5 per cent of the maximum voluntary contraction (MVC) to 30 per cent MVC while the depth of modulation was held constant at ±5 per cent of MVC. In the second series of experiments the mean torque was held constant at 25 per cent MVC while the depth of modulation was varied from ±2.5 per cent to ±25 per cent. The major findings were: (1) A second-order, low-pass filter provided a good quasilinear model of the EMG/force dynamics under all conditions; (2) The model parameters depended only weakly on the mean level of torque; (3) In contrast, the model parameters depended strongly on the amplitude with which the contraction was modulated; the natural frequency increased significantly with the depth of modulation.     

Rare-male mating advantage: An artifact caused by differential storage conditions?

Virgin males (or females) of some species ofDrosophila, when stored singly, are known to be superior in mating to males (or females) stored in groups. This may create a spurious rare-male effect on some occasions. When no account is taken of this storage effect in an experimental setup designed to show rare-male mating advantage, bias in favor of a raremale effect may result. It is shown that merely by storing the rare males singly and the common males in groups, with males not differing in any other respect, a very strong spurious rare-male effect can be produced. Similarly, it is shown that a spurious rare-female effect is possible too. It is proposed that the very strong rare-male effect for pepperment scent as found by Dal Molin [(1979).Am. Nat. 113:951–954] is merely a result of such a bias. The relevance for natural populations of the mating advantage associated with the single housing condition is discussed. In the experiments designed to show a spurious rare-male effect, mating chambers of two different sizes were used. It is shown that sexual selection is more severe in the small chambers, for both males and females.     

以腓动脉终末穿支为蒂的皮瓣应用解剖

在33侧成人标本上,观察了以腓动脉的终末穿支为蒂的外踝上皮瓣血供。腓动脉终末穿支在外踝上方5.9cm 处,穿出骨间膜,外径为1.7mm,本干长为0.7cm,分为升支和降支、有91%的个体,以穿动脉的升支为蒂,设计为外踝上皮瓣:以穿动脉的降支为蒂,设计为足外侧皮瓣。在9%的个体中,腓动脉穿支细小,不能作为皮瓣的血管蒂,只能改用外踝前动脉升支为蒂的外踝上皮瓣.     

以骨间前血管为蒂前臂骨膜骨瓣的临床应用

应用骨间前血管为蒂.桡、尺骨骨膜骨瓣移位治疗上肢骨不连或骨缺损38例,均获得成功。该术式与以桡、尺动脉为蒂的桡、尺骨骨膜骨瓣移位相比较,有不损伤前臂主要血管干、移位范围大、适应症较广和操作简便易推广等特点.