Multi-joint limbs permit a flexible response to unpredictable events

The human arm is kinematically redundant, which may allow flexibility in the execution of reaching movements. We have compared reaching movements with and without kinematic redundancy to unpredictable double-step targets. Subjects sat in front of a digitising tablet and were able to view an arc of four targets reflected in the mirror as virtual images in the plane of the tablet. They were instructed to move, from a central starting point, in as straight a line as possible to a target. In one-third of trials, the target light switched to one of its neighbours during the movement. Subjects made 60 movements using shoulder, elbow and wrist and then another 60 movements in which only shoulder and elbow movement were allowed. By restraining the wrist, the limb was made non-redundant. The path length was calculated for each movement. In single-step trials, there was no significant difference between path lengths performed with and without wrist restraint. As expected there was a significant increase in path length during double-step trials. Moreover this increase was significantly greater when the wrist was restrained. The variability across both single- and double-step movements was significantly less while the wrist was restrained. Importantly the performance time of the movements did not alter significantly for single-step, double-step or restrained movements. These results suggest that the nervous system exploits the intrinsic redundancy of the limb when controlling voluntary movements and is therefore more effective at reprogramming movements to double-step targets. Received: 24 March 1997 / Accepted: 7 July 1997     

补肾中药对雄激素致不孕大鼠卵巢核仁组成区蛋白的影响

观察补肾中药对雄激素致不孕大鼠卵巢核仁组成区蛋白的影响。用ＳＤ雌性大鼠幼仔，出生９ｄ龄注射丙酸睾丸酮，制成雄激素致不孕大鼠（ＡＳＲ）模型。８０ｄ龄灌服补肾中药水溶液两周。１００ｄ龄心脏灌注处死。以核仁组成区蛋白嗜银染色（ＡｇＮＯＲ）和增殖细胞核杭原（ＰｃＮＡ）为指标，观察卵巢颗粒细胞、间质腺细胞的形态学变化。结果：补肾中药能够使ＡＳＲ卵巢颗粒细胞增殖、卵泡发育。治疗组的ＡｇＮＯＲ和ＰｃＮＡ计数明显高于模型组，而与对照组之间无显著差异。结论：补肾中药的这种作用可能是通过调节了下丘脑－垂体－卵巢性腺功能的结果，从而促使卵巢颗粒细胞发育、卵泡成熟。     

大气中不同粒径颗粒物诱导人羊膜FL细胞UDS的研究

本研究以诱导人羊膜细胞ＵＤＳ为指标，对太原市大气不同粒径的颗粒物提取液进行了致突变性检验，结果表明，不同粒径颗粒物的提取液均可产生一定的遗传毒性，尤以３．３μｍ以下的颗粒物的遗传毒性较强。     

Human Y-79 retinoblastoma cells express functional corticotropin-releasing hormone receptors

In human Y-79 retinoblastoma cells corticotropin-releasing hormone (CRH) produces a marked and rapid increase of adenylate cyclase activity. The concentration of the peptide producing half-maximal stimulation is 60 nM. The effect of CRH is significantly antagonized by the specific CRH receptor antagonist alpha-helical CHR 9-41 and is mimicked by sauvagine and urotensin I, two peptides displaying sequence homology with CRH. These results demonstrate the presence of functional CRH receptors in human Y-79 retinoblastoma cells and suggest that this cell line may be a suitable model in which to study the action of CRH on human retinal cell function.     

Tau protein induces bundling of microtubules in vitro: comparison of different tau isoforms and a tau protein fragment.

Expression of tau protein in non-neuronal cells can result in a redistribution of the microtubule cytoskeleton into thick bundles of tau-containing microtubules (Lewis et al.: Nature 342:498-505, 1989; Kanai et al.: J Cell Biol 109:1173-1184, 1989). We reconstituted microtubule bundles using purified tubulin and tau in order to study the assembly of these structures. Taxol-stabilized tubulin polymers were incubated with various concentrations of recombinant human tau and examined by electron microscopy. With increasing concentrations of tau 3 (tau isoform containing three microtubule binding domains) or tau 4 (isoform containing four microtubule binding domains) the microtubules changed orientation from a random distribution to loosely and tightly packed parallel arrays and then to thick cables. In contrast, tau 4L, the tau isoform containing four microtubule binding domains plus a 58-amino acid insert near the N-terminus, showed minimal bundling activity. tau 4-induced bundling could be inhibited by the addition of 0.5 M NaCl or 0.4 mM estramustine phosphate, conditions which are known to inhibit tau binding to microtubules. A tau construct that contained only the microtubule binding domains plus 19 amino acids to the C-terminus was fully capable of bundling microtubules. Phosphorylation of tau 3 with cAMP-dependent protein kinase had no effect on its ability to induce microtubule bundling. These results indicate that tau protein is directly capable of bundling microtubules in vitro, and suggests that different tau isoforms differ in their ability to bundle microtubule filaments.     

Involvement of synthesis of brain cell structural proteins in the action of antitheines on long-term memory

Academician S. V. Anichkov Department of Pharmacology, Research Institute of Experimental Medicine, Academy of Medical Sciences, St. Petersburg. (Presented by Academician of the Academy of Medical Sciences A. N. Klimov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 5, pp. 506–508, May, 1992.     

Different effects of unilateral versus bilateral subthalamic nucleus stimulation on walking and reaching in Parkinson's disease.

The purpose of this study was to determine the effects of unilateral versus bilateral subthalamic nucleus (STN) stimulation on quantitative measures of walking and reaching in Parkinson's disease (PD). We used kinematic measures and the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscale (subscale III) to evaluate the movement of 6 people with PD who had bilateral STN stimulators implanted for at least 6 months and withheld their anti-parkinson medication for at least 8 hours. Subjects were studied with both stimulators off, one on, and both on. Kinematic data were collected as subjects walked, reached to a target, and were rated using the UPDRS motor subscale. STN stimulation improved walking speed and stride length, with the greatest benefit from bilateral stimulation. Reaching speed was improved by unilateral STN stimulation alone, with no additive effect of bilateral stimulation. UPDRS motor subscale ratings paralleled the kinematic findings. STN stimulation did not restore PD subjects' movements to the level of age-matched controls. Overall, these results provide further evidence that the basal ganglia pathways involved in control of walking and reaching may be distinct. We speculate that basal ganglia may influence walking through bilateral pedunculopontine projections and reaching through ipsilateral thalamocortical projections. Our findings also suggest that maximal improvement of walking requires bilateral rather than unilateral STN stimulation.     

大鼠头颅瞬间侧向旋转后脑干水肿的形成及其超微形态学基础

目的：探讨头颅瞬间旋转后脑干水肿的形成及超微形态学基础。     

Oral tolerance in EAE: reversal of tolerance by T helper cell cytokines

Oral administration of myelin basic protein (MBP) inhibits clinical and histopathological manifestations of experimental autoimmune encephalomyelitis (EAE), but only partially reduces serum anti-MBP antibody titers. We report here that orally administered MBP alters the isotypic distribution of anti-MBP antibody-forming cells (AFC) among various lymphoid tissues, with the most profound differences seen in mucosal tissues. We observed an isotype-selective reduction in anti-MBP IgA but not IgM AFC frequencies in Peyer's patches. The anti-MBP IgA AFC frequencies could be reconstituted by addition of interleukin 4 (IL-4) and interleukin 5 (IL-5). The cytokines did not appear to generate de novo responses since no increases in anti-MBP IgA AFC frequencies were observed in control cultures. These results indicate that decreased antibody production, as a result of oral antigen administration, can be reversed by exposure to the appropriate cytokines.     

Evidence for the presence of substance P-like immunoreactivity in the human cerebellum

Preliminary results on the localization of substance P-like immunoreactivity in the human cerebellum are presented. Cerebella from newborn and adult subjects were examined. While only sporadic positive fibres were detected in the adult tissue, the immunoreactive material appeared more abundant in the cerebella from newborn subjects. Varicose and non-varicose fibres and dot-like nerve terminals were present with different density in various regions. The paucity of immunoreactive perikarya suggests that most of the cerebellar substance P-like immunoreactive material has an extrinsic origin.