Functional coupling of the stabilizing eye and head reflexes during horizontal and vertical linear motion in the cat

Summary The otolith contribution and otolith-visual interaction in eye and head stabilization were investigated in alert cats submitted to sinusoidal linear accelerations in three defined directions of space: up-down (Z motion), left-right (Y motion), and forward-back (X motion). Otolith stimulation alone was performed in total darkness with stimulus frequency varying from 0.05 to 1.39 Hz at a constant half peak-to-peak amplitude of 0.145 m (corresponding acceleration range 0.0014–1.13 g) Optokinetic stimuli were provided by sinusoidally moving a pseudorandom visual pattern in the Z and Y directions, using a similar half peak-to-peak amplitude (0.145 m, i.e., 16.1°) in the 0.025–1.39 Hz frequency domain (corresponding velocity range 2.5°–141°/s). Congruent otolith-visual interaction (costimulation, CS) was produced by moving the cat in front of the earth-stationary visual pattern, while conflicting interaction was obtained by suppressing all visual motion cues during linear motion (visual stabilization method, VS, with cat and visual pattern moving together, in phase). Electromyographic (EMG) activity of antagonist neck extensor (splenius capitis) and flexor (longus capitis) muscles as well as horizontal and vertical eye movements (electrooculography, EOG) were recorded in these different experimental conditions. Results showed that otolith-neck (ONR) and otolith-ocular (OOR) responses were produced during pure otolith stimulation with relatively weak stimuli (0.036 g) in all directions tested. Both EMG and EOG response gain slightly increased, while response phase lead decreased (with respect to stimulus velocity) as stimulus frequency increased in the range 0.25–1.39 Hz. Otolith contribution to compensatory eye and neck responses increased with stimulus frequency, leading to EMG and EOG responses, which oppose the imposed displacement more and more. But the otolith system alone remained unable to produce perfect compensatory responses, even at the highest frequency tested. In contrast, optokinetic stimuli in the Z and Y directions evoked consistent and compensatory eye movement responses (OKR) in a lower frequency range (0.025–0.25 Hz). Increasing stimulus frequency induced strong gain reduction and phase lag. Oculo-neck coupling or eye-head synergy was found during optokinetic stimulation in the Z and Y directions. It was characterized by bilateral activation of neck extensors and flexors during upward and downward eye movements, respectively, and by ipsilateral activation of neck muscles during horizontal eye movements. These visually-induced neck responses seemed related to eye velocity signals. Dynamic properties of neck and eye responses were significantly improved when both inputs were combined (CS). Near perfect compensatory eye movement and neck muscle responses closely related to stimulus velocity were observed over all frequencies tested, in the three directions defined. The present study indicates that eye-head coordination processes during linear motion are mainly dependent on the visual system at low frequencies (below 0.25 Hz), with close functional coupling of OKR and eye-head synergy. The otolith system basically works at higher stimulus frequencies and triggers Synergist OOR and ONR. However, both sensorimotor subsystems combine their dynamic properties to provide better eyehead coordination in an extended frequency range and, as evidenced under VS condition, visual and otolith inputs also contribute to eye and neck responses at high and low frequency, respectively. These general laws on functional coupling of the eye and head stabilizing reflexes during linear motion are valid in the three directions tested, even though the relative weight of visual and otolith inputs may vary according to motion direction and/or kinematics.     

Characteristics of steroid hormone binding systems in hepatocyte plasma membranes

Parameters of binding of cortisone and estradiol to plasma membranes of rat hepatocytes were studied by the method of liquid scintillation radiometry. The presence of two systems for the binding of these hormones in the membranes was demonstrated. One system is specific (saturable) and binds hormones in physiological concentrations. The capacity and affinity of this system for cortisone are significantly higher than for estradiol. The binding parameters within the temperature range from 4 to 37°C for cortisone and estradiol respectively are: Dissociation constant 2.1–3 and 2.7–4.5 nM, number of binding sites 2–2.4 and 0.14–0.18 nmoles/mg protein. Experiments with p-chloromercuribenzoate demonstrate the role of proteins in the working of this system. The second (unsaturable) system is nonspecific and its function is determined by the lipid component of the membranes. The affinity of corticosteroids for hepatocytes is probably due to the activity of the (saturable) specific system of the plasma membranes of these cells.Department of Molecular Pharmacology and Radiobiology, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 172–174, February, 1980.     

Cholecystokinin and neurotensin mRNAs are differentially expressed in subnuclei of the ventral tegmental area

Immunohistochemical studies of ventral tegmental area (VTA) neurons indicate that individual cells can contain dopamine as well as the neuropeptide neurotransmitters cholecystokinin (CCK) and neurotensin (NT). We have defined the distribution of the cells expressing the mRNAs encoding these two dopamine cotransmitter peptides in each of the subnuclei of the ventral tegmental area, and quantitated the extent of expression of each gene by using in situ hybridization methods. These studies reveal significant differences in the patterns of expression of each of these two genes within various subdivisions of the VTA. The rostral linear nucleus contained numerous CCK positive cells, some of which appeared to express preproCCK-mRNA at a very high level, but this nucleus contained relatively few NT-expressing cells. The parabrachialis pigmentosus contained numerous NT and CCK positive cells. The paranigralis and interfascicularis nuclei displayed positive CCK cells but with expression at only modest levels. NT cells were very few in these nuclei. The caudal linear nuclei contained the highest number of NT-expressing neurons and these cells expressed very high levels of NT mRNA. The selective distribution of these peptide genes within the VTA subnuclei may have specific consequences. Studies of the connectivity of neurons in the VTA show that the different subnuclei of this region project to several functionally and architectonically different regions of the cerebral cortex and subcortically to nuclei related to the limbic system. Results from our study show very prominent expression of CCK mRNAs in those subnuclei that project heavily to the prefrontal, other cortical areas, and the amygdaloid complex. The NT gene is expressed prominently in those subnuclei of VTA that project heavily to the entorhinal cortex and amygdaloid complex. These results provide support for a differential role for the NT-expressing neurons than that of CCK-expressing neurons of VTA in "reward" mechanisms and in drug-seeking and motivational behavior. These observations could be applied to create working hypotheses and experimental paradigms to test the differential functional activity of the subdivisions of VTA and their potential roles in the pathogenesis and treatment of drug-seeking behavior and other neuropsychiatric disorders.     

Estimating the financial savings from maintaining the level of acute services with fewer hospital beds

All district health authorities are obliged to use resources most efficiently. One approach to increasing efficiency is to identify measures which allow service levels, in terms of patients treated and standards of care, to be maintained at a lower cost. This could be achieved by maintaining service levels with fewer hospital beds. Reducing lengths of stay by removing organizational delays and expansions of day-case care, are policies which can increase patient caseload per bed. This paper puts forward an approach for estimating the resources released by such policies and assesses the savings achieved by realizing efficiency gains identified in a previous study by Beech et al. (1987). That study identified significant potential for maintaining services with fewer beds, with the expansion of day-case care being a key mechanism. However this paper concludes that when services are maintained with fewer beds, the vast majority of hospital costs remain fixed. It also reaches the alarming conclusion that as a vehicle for reducing costs, day-case care is much less effective than previous studies have implied. However, increasing hospital throughput per bed does release capacity to treat more patients. The proposed reforms of the NHS (Secretaries of State, 1989) envisage an internal market for health care, allowing hospitals to enter into contracts with purchasers of health care. The approach to costing described in this paper is applicable to assessing the increased costs associated with such developments. These extra costs can then be compared with expected income.     

无框架脑立体定向手术在微创神经外科中的应用

目的 探讨无框架脑立体定向手术在微创神经外科的应用价值。方法 术前行MRI或CT检查,将数据输入导航系统,进行头颅或脊髓三维模型重建,设计手术切口和入路,术中实时定位。1999年11月－2001年6月进行无框架脑立体定向手术200例,其中颅内动静脉畸形43例,动脉瘤39例,脑膜瘤30例,海绵状血管瘤27例,胶质瘤19例,神经鞘瘤8例,垂体腺瘤5例,血管网织细胞瘤4例,转移癌3例,其他14例;脊髓肿瘤8例。结果 病灶和重要解剖结构定位准确,病灶定位误差均在2mm以内,术后神经功能损害10例,占5．0％,无手术死亡。结论 无框架脑立体定位手术对脑和脊髓手术,尤其是切除脑深部病灶很有帮助,可以准确发现病灶,保护正常神经组织,改变了传统神经外科手术模式,是微创神经外科的保障。     

全自动细菌分析系统检测耐甲氧西林葡萄球菌的初步评价

采用琼脂筛选法、纸片扩散法和仪器法平行进行葡萄球菌苯唑西林敏感性的测定 ,同时进行微生物敏感性试验。结果显示 :MRS的分离率为 5 4.4% ,琼脂筛选法和仪器法两法对MRS检测的符合率为 96 .7%。MRS对万古霉素最敏感 ,敏感率 10 0 % ;呋喃妥因次之 (耐药率 0 .0 2 4% )。VITEK32型细菌分析系统可准确检测MRS。认为MRS以万古霉素治疗效果最佳 ,其次为呋喃妥因     

生态药理与生物药理—论中药药性理论的本质

目的：探讨中药药性理论的本质,方法：通过对医学人体理论,医学模式和药理理论内在关系的分析来剖析中药药性理论的本质,提出对中药药性理论本质的认识。结果：认为中药药性理论是传统中药药理理论,是适应中医学“生态－生物人体理论”的产物,中药药性理论是“生态药理”与“生物药理”相结合的产物即“生态－生物理”这是其本质所在,结论：传统中药药理即中药药性理论是“生态－生物药理”理论。     

膜表面型与可溶型HLA-B27 分子在人C1R细胞内的细胞生物学研究

目的 :了解两型HLA B2 7分子在人细胞系内的合成、组装及转运过程。方法 :克隆到真核表达载体RSV 5neo的膜表面型与可溶型B2 7(sB2 7)cDNA以电转法转入人B淋巴母细胞突变细胞系C1R ,并使其稳定表达。以免疫沉淀、脉冲追踪及内切糖苷酶H消化实验观察两型B2 7分子在C1R细胞系内的细胞生物学特点。结果 :sB2 7分子与膜表面型B2 7分子一样 ,约需 30min完成细胞内的修饰过程 ,均与Calnexin及BiP这两种分子伴侣相关等 ,但与膜表面型B2 7分子相比 ,仅部分sB2 7分子被转运到细胞表面 ,相当一部分sB2 7分子 4h后仍滞留在内质网腔内。结论 :sB2 7分子在人C1R细胞内的合成、组装与转运过程与膜表面型B2 7分子相似 ,滞留在内质网腔的sB2 7分子的酶解片段有可能通过Ⅱ类分子而递呈给CD4 T细胞 ,这一现象将为研究HLA Ⅱ类分子与脊柱关节病的相关提供新线索 ,并为今后探讨B2 7及环境因素与脊柱关节病的相关、寻找早期诊断与早期治疗措施提供理论依据     

温州地区鼠类肝毛细线虫流行学和生物学研究

目的：了解温州地区鼠体肝毛细线虫的感染情况,为肝毛细线虫病防治提供科学依据,并探讨肝毛线虫幼虫经皮肤和经腹腔注射感染小白鼠的可行性。方法：从温州境内部分地区收集鼠体以检查肝毛细线虫虫卵,分离虫卵并培养成幼虫作感染小白鼠试验。结果：温州地区鼠及臭 毛细线虫总感染率是１８．３％,不同鼠种和硒居范围不同的鼠体感染率不同,鼠体感染率和感染度随鼠体年龄增大而增高（强）。肝毛细线虫幼虫经皮肤和经腹腔注射感染小     

Basic Science in Medical Reasoning: An Artificial Intelligence Approach

A new generation of intelligent systems is growing up in the community of Artificial Intelligence in Medicine. The main goal of these systems is the representation and use of real theory of diseases, as they are represented in medical textbooks or in scientific articles, rather than the heuristic shortcuts of human experts. In this paper, we will argue that the difficulties in the integration of basic science and clinical knowledge in intelligent systems arise from ontological differences between these kinds of knowledge and that the solution can be found in their dynamic integration during the reasoning process. In order to illustrate this point, we will first describe an epistemological analysis of the interplay between basic science knowledge and clinical knowledge, and then we will provide the example of a computational architecture implementing this view. This revised version was published online in June 2006 with corrections to the Cover Date.