Ratio of shear to load ground-reaction force may underlie the directional tuning of the automatic postural response to rotation and translation

This study sought to identify the sensory signals that encode perturbation direction rapidly enough to shape the directional tuning of the automatic postural response. We compared reactions to 16 directions of pitch and roll rotation and 16 directions of linear translation in the horizontal plane in freely standing cats. Rotations and translations that displaced the center of mass in the same direction relative to the feet evoked similar patterns of muscle activity and active ground-reaction force, suggesting the presence of a single, robust postural strategy for stabilizing the center of mass in both rotation and translation. Therefore we postulated there should be a common sensory input that encodes the direction of the perturbation and leads to the directional tuning of the early electromyographic burst in the postural response. We compared the mechanical changes induced by rotations and translations prior to the active, postural response. The only consistent feature common to the full range of rotation and translation directions was the initial change in ground-reaction force angle. Other variables including joint angles, ground-reaction force magnitudes, center of pressure, and center of mass in space showed opposite or nonsignificant changes for rotation and translation. Change in force angle at the paw reflects the ratio of loading force to slip force, analogous to slips during finger grip tasks. We propose that cutaneous sensors in the foot soles detect change in ground-reaction force angle and provide the critical input underlying the directional tuning of the automatic postural response for balance.     

The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry

Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus is determined by a combination of environmental and genetic factors, which include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2 cannot explain the clustering of type 1 diabetes in families, and a role for other genes is inferred. In the present report we describe linkage and association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong candidate gene for T cell- mediated autoimmune disease because it encodes a T cell receptor that mediates T cell apoptosis and is a vital negative regulator of T cell activation. In addition, we provide supporting evidence that CTLA-4 is associated with susceptibility to Graves' disease, another organ- specific autoimmune disease.      

NMDA受体在正常大鼠颈动脉体的表达

应用免疫组织化学方法观察了离子型谷氨酸受体——NMDA受体的NR1及NR2A亚单位在正常成年雄性SD和Wistar大鼠颈动脉体的表达,并对阳性产物的表达强度进行了灰度分析及统计学处理。结果表明:正常成年SD大鼠及Wistar大鼠的颈动脉体内均存在NMDA NR1免疫反应阳性细胞,从阳性细胞的形态和分布特点判断这些阳性细胞为主细胞,两种大鼠之间无明显差异(P>0.05);而两种大鼠的颈动脉体内几乎不存在NMDA NR2A免疫反应阳性细胞。本实验的结果提示:在正常成年大鼠颈动脉体的主细胞上有NMDA受体的分布,并且该受体的二聚体构成不同于经典受体,这可能与谷氨酸在颈动脉体发挥的特殊功能有关。     

大鼠FEZ1基因的克隆及其在中枢神经系统的表达

轴突成束和延伸蛋白ζ-1(fasciculationandelongationproteinzeta-1,FEZ1),是线虫UNC-76蛋白在哺乳动物中的一种同系物,与轴突向外生长、成束、延伸相关。为了克隆该蛋白的基因并观察其在中枢神经系统(CNS)的表达情况,本研究通过FEZ1的特异引物从SD大鼠脑组织中经逆转录-聚合酶链反应(RT-PCR)获得FEZ1基因;通过RT-PCR法分析FEZ1在生后7d的SD大鼠CNS的不同部位(大脑皮层、嗅球、脊髓)的表达情况。成功获得FEZ1的基因克隆,并观察到生后7d的SD大鼠的大脑皮层、嗅球、脊髓内均有FEZ1表达,且脊髓的表达水平较高。本研究结果为进一步研究大鼠FEZ1基因的生物学活性及在神经系统内的表达和应用奠定了基础。     

The incidence and clinical implications of hypersensitivity to papain in an allergic population, confirmed by blinded oral challenge

Five hundred allergy clinic patients were prick skin tested with papain, 1 mg/mL, in addition to usual local aeroallergens. Five of 475 subjects with seasonal allergic disease had positive skin tests to both papain and local pollens. None of the 25 individuals with negative skin test to pollens had skin reactivity to papain. The five subjects with positive skin tests to papain underwent double-blind placebo-papain challenges. All papain challenges were positive. Placebo challenges were negative. Papain-induced symptoms included palatal itching, watering itchy eyes, sneezing, rhinorrhea, abdominal cramps, diarrhea, and diaphoresis. Circulating papain-specific IgE was detected in all the papain-sensitive individuals, but not in control subjects. Confirmed papain sensitivity occurred in 1.05% of allergic subjects. In the papain-sensitive patients, cross-reacting antibodies with chymopapain were found. The small number of non-allergic subjects did not show any papain or chymopapain sensitivity in vitro.     

CD3+木瓜提取物对ApoE基因缺陷小鼠血脂及炎性相关因素的影响

目的观察木瓜提取物对ApoE基因缺陷小鼠血脂水平、主动脉窦斑块中巨噬细胞活化及肿瘤坏死因子(TNF-α)水平的影响。方法30只雄性ApoE基因缺陷小鼠随机分为3组:对照组、低剂量组和高剂量组,低剂量组和高剂量组分别在基础饲料上添加5%和10%的木瓜提取物喷雾干燥颗粒,饲养16周后经小鼠眼眶静脉取血后处死动物,酶法测定血脂水平、采用免疫组化分析主动脉窦斑块中TNF-α的表达水平和采用免疫荧光反映斑块CD68阳性表达水平与巨噬细胞阳性表达率。结果低剂量组和高剂量组的血清TC和LDL-C显著低于对照组(P<0.05),木瓜提取物能显著下调斑块中TNF-α的表达水平以及减少巨噬细胞的阳性率。结论木瓜提取物降低了血清脂蛋白胆固醇水平(TC和LDL-C),减少了炎性因子TNF-α表达以及减弱巨噬细胞参与程度,预示其可能具有减缓动脉斑块发生发展的抗动脉粥样硬化作用。     

兔眼前房压强在体连续测量方法的研究

为了解眼睛房水压强变化规律,进一步建立闭角型青光眼模型和对疾病的治疗及视功能康复提供参考,探讨一种在体连续测量正常兔眼前房压强的方法。将正常成年新西兰白兔麻醉后,先用静脉留置针(20G)自角膜缘外行前房穿刺术,然后通过套管将Millar导管植入兔眼的前房,兔眼的前房压强信号经过Powerlab系统进行滤波、放大和模数转换后,通过Chart软件进行实时显示。结果表明:用该方法测得的正常兔眼24 h前房压强的变化范围为(1.31±0.21—2.74±0.83)KPa。前房压强的分布凌晨较低(0~5点),然后逐渐升高(5~10点),到中午或下午(11—17点)时达到最高峰,晚上又逐渐下降(18~23点)。结果证明本实验在体连续测量兔眼前房压强的方法是可行的。