Electrical activity of red nucleus neurones investigated with intracellular microelectrodes

Summary Microelectrodes were inserted into the magnocellular portion of cat's red nucleus (RN), and some basic physiological properties of RN cells were examined by both extra- and intracellular recording. During stimulation of the rubrospinal fibres at the spinal segmental level, the RN cells were invaded antidromically, producing conspicuous field potentials within RN. The somatotopical distribution of RN cells was confirmed by comparing the field potentials induced from C₂ and L₁ levels. When recorded intracellularly, antidromic action potentials showed three-step configuration as those in motoneurones and were followed by a remarkable after-hyperpolarization. The conduction velocity along the rubrospinal fibres ranged from 41–123 m/sec, with the peak frequency at 91–100 m/sec. The membrane properties were examined in some RN cells by intracellular application of current steps. The total membrane resistance was 4 M on the average, and the membrane time constant 6 msec, respectively.Excitatory postsynaptic potentials (EPSPs) were induced monosynaptically in RN cells by stimulation of the nucleus interpositus of the contralateral cerebellum. Their time course was analyzed in comparison with that of the potentials produced by current steps. Stimulation in the ventrolateral nucleus of the thalamus evoked monosynaptic EPSPs via the collaterals of the interpositus axons which innervate RN and thalamus commonly. It was further shown that impulses in cortico-rubral fibres produced EPSPs in RN cells. These cerebral-evoked EPSPs were characterized by much slower time courses than those from the nucleus interpositus.     

A physicomathematical approach to the structure of the mandible

Summary Classical methods of anatomical study and experimentation have reached an endpoint with respect to the advancement of our knowledge of certain aspects of bone, i.e. its mechanical properties, investigation of the constraints acting on bone and the organization of bone allowing resistance to such mechanical stress. Indeed, current knowledge is rather limited regarding bone as a material. Furthermore, bone from the cadaver cannot be considered a reliable source of study material since its physicochemical composition and mechanical properties are highly different from those of living bone. The types of experimentation used to date, although allowing to study the phenomena occuring on the surface of the bone, do not allow to evaluate those that occur within the bone without modification of its mechanical features. Finally, the number and complexity of the parameters to be taken into account in this respect largely supersede the possibilities of classical study techniques.Accordingly, new types of methodology are required to evaluate the many parameters involved, to perform the corresponding computations and resolve the great number of unknown variables. Such methodology must allow experimentation to be performed without modifying the object of study and to determine the phenomena occuring within the bone itself, i.e. the mandible.A method of computer assisted simulation of a physicomathematical model was used to analyse the structural properties of the mandible. This method was based on that used for the computation and elaboration of large metal structures (offshore drilling platforms), structures submitted to special stress (resistance to force 7 earthquake of the new extension to the radioactive waste disposal factory at the Hague) or aeronautical structures composed of composite material.

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Approche physico-mathématique structurale de la mandibule

Résumé L'étude des propriétés mécaniques de l'os, celle des contraintes qu'il subit, la manière dont il est organisé pour résister à ces contraintes s'avèrent déboucher sur une impasse si l'on se contente des méthodes classiques d'études et d'expérimentations.En effet, nous n'avons actuellement qu'une connaissance très limitée de l'os en qualité de matériau. Le matériau d'expérimentation, l'os de cadavre ne peut être considéré comme fiable, sa constitution physico-chimique et ses propriétés étant par trop différentes de celles de l'os vivant. Le type même des expérimentations utilisées, s'il permet bien d'étudier ce qui se passe à la surface de l'os ne permet pas de prendre en compte ce qui se passe à l'intérieur de celui-ci sans en modifier les caractéristiques mécaniques. Enfin, le nombre et la complexité des paramètres à prendre en compte dépassent largment les possibilités des techniques classiques. C'est pourquoi, il est nécessaire de faire appel à des méthodologies nouvelles capables de prendre en compte un nombre très élevé de paramètres, de les calculer et de résoudre un nombre très important d'inconnues. Ces méthodologies doivent permettre l'expérimentation sans modifier l'objet de l'expérience et de calculer ce qui se passe à l'intérieur même de la mandibule.Cette méthode de simulation sur modèle physico-mathématique par informatique utilisée pour le calcul et l'élaboration des grandes structures métalliques (plate-forme off shore), celui de structures placées dans des conditions de contraintes particulières (prise en compte des tremblements de terre de magnitude 7 pour l'extension de l'usine de La Hague) ou bien celui des structures aéronautiques à matériaux composites a été ici appliquée à l'étude structurale de la mandibule.

     

生物组织光传播特性的研究

光在组织中传播与组织的光学性质有关。折射率是组织光学性质最基本的参数,用来评价组织改变光线行进方向的参量。本文以菲涅耳公式为理论依据,尝试用空气—组织界面的反射率、生物组织薄膜的反射率和生物组织反射光的偏振分量,推算生物组织的折射率。 本文还探测了组织的前向散射和后向漫射分布。     

具有多重玻璃化转变的梳状聚合物的合成,表征和导电性：侧链 …

以分子量为５５０的聚乙二醇单甲醚为侧链,苯乙烯／马来酸酐共的为骨架,合成了苯乙烯／马来酸酐共聚物多缩乙二醇酯。用红外光谱、元素分析、ＤＳＣ、热失重等方法,对合成条件、产物结构和性能进行了研究。结果表明：反应严格按照反应方程进行,精制产物是非晶的梳状聚合物。玻璃化转变温度为３０．６８℃,分解温度为１２０℃。对动态这性能及其锂盐复合物离子导电性进行了研究,表明α转变温度和β转变温度分别是２８℃他－４７     

加压三相淤浆床环氧乙烷合成过程研究V. 二号液相热载体物性数据的测定和关联

测定了三相淤浆床环氧乙烷合成过程所用惰性液相热载体的物性数据,包括表面张力、密度、粘度、比热容等,并对实验数据进行了回归,得到各种物性数据和温度的关联式.     

醋酸乙烯—二乙烯基苯共聚反应动力学

根据文献查得的Ｑ,ｅ值,计算了醋酸乙烯－二乙烯基二元共聚的竞聚率,预测其共聚的可能性。以甲苯为汽油为致孔剂,采用悬浮聚合方法合成该二元大孔共聚物。红外光谱分析跟踪共聚反应过程中乙酰氧基和苯环相对比例的变化,并测定共聚反应过程中比表面积,孔率和平均孔径的变化。     

多检测GPC/SEC技术在高分子表征中的应用Ⅳ.氘化高分子的溶液性质

采用体积排斥色谱法／ 示差折光指数／ 直角激光光散射／ 示差粘度三检测联用技术表征了氘化聚苯乙烯、聚苯乙烯和氘化聚苯乙烯－ 聚异戊二烯。结果表明,在θ条件下,虽然氘化聚苯乙烯的化学依赖性常数υＴ,ＤＰＳ比聚苯乙烯的化学依赖性常数υＴ,ＰＳ大,但２５ ℃时在四氢呋喃中,氘化聚苯乙烯的分子尺寸仍小于聚苯乙烯的分子尺寸。由于嵌段共聚物的淋洗体积随组成变化,所以用传统的ＳＥＣ／ＲＩ得不到准确的分子量。经比较膜渗透、小角激光光散射和基质辅助激光脱吸与离子化时间飞行质谱等的实验结果,证明体积排斥色谱法／ 示差折光指数／ 直角激光光散射／ 示差粘度三检测技术能准确地得到氘化二嵌段共聚物的分子量以及其它重要信息。     

A Kiswahili version of the SF-36 Health Survey for use in Tanzania: translation and tests of scaling assumptions

The objective of the study was to translate and adapt the SF-36 Health Survey for use in Tanzania and to test the psychometric properties of the Kiswahili SF-36. A cross-sectional study was conducted as part of a household survey of a representative sample of the adult population of Dar es Salaam, Tanzania. The IQOLA method of forward and backward translation was used to translate the SF-36 into Kiswahili. The translated questionnaire was administered by trained interviewers to 3,802 adults (50% women, mean (SD) age 31 (13) years, 50% married and 60% with primary education). Data quality and psychometric assumptions underlying the scoring of the eight SF-36 scales were evaluated for the entire sample and separately for the least educated subgroup (n=402), using multitrait scaling analysis. Forward and backward translation procedures resulted in a Kiswahili SF-36 that was considered conceptually equivalent to the US English SF-36. Data quality was excellent: only 1.2% of respondents were excluded because they answered less than half of the items for one or more scales; ninety percent of respondents answered mutually exclusive items consistently. Median item–scale correlations across the eight scales ranged from 0.47 to 0.81 for the entire sample. Median scaling success rates were 100% (range 87.5–100.0). The median internal consistency reliability of the eight scales for the entire sample was 0.81 (range 0.70–0.92). Floor effects were low and ceiling effects were high on five of the eight scales. Results for n=402 people without formal education did not differ substantially from those of the entire sample. The results of data quality and psychometric tests support the scoring of the eight scales using standard scoring algorithms. The Kiswahili translation of the SF-36 may be useful in estimating the health of people in Dar es Salaam. Evidence for the validity of the SF-36 for use in Tanzania needs to be accumulated.     

Measuring health-related quality of life in patients with venous leg ulcers

Introduction: The effect on quality of life by healing leg ulcers is not known and no validated disease-specific tool is available for measuring health-related quality of life (HRQoL) for people with venous leg ulcers. The objective of this paper was to compare four generic instruments [MOS 36-Item Short-Form Health Survey (SF-36); EuroQol (EQ); McGill Short Form Pain Questionnaire (SF-MPQ) and the Frenchay Activities Index (FAI)] used for measuring HRQoL in people with venous leg ulcers, and to offer guidance on the most appropriate tool for researchers. Methods: Two hundred and thirty-three patients with venous leg ulcers were recruited as part of a randomised controlled trial of the cost-effectiveness of community leg ulcer clinics. Subjects completed questionnaires containing the four instruments on three occasions (initial assessment, 3 and 12 months). The discriminative and evaluative properties of the four instruments were compared. Results: All four instruments were acceptable to patients, taking a mean of 19.3 (SD 6.3) min to complete. At initial assessment, the SF-MPQ had poorer discriminative properties than the other three instruments and was not able to distinguish between the different patient groups in relation to age and ulcer duration. The FAI was good at discriminating between the different patient groups (at initial assessment) in relation to age, mobility and ulcer size. At the three-month follow-up, the SF-MPQ was more responsive than the other measures and detected changes in HRQoL, whereas the EQ and SF-36 did not. At 12 months, the SF-MPQ still identified differences and the SF-36 and EQ also did at this stage. Conclusion: In the absence of a validated condition-specific tool for measuring changes in general health status for patients with venous leg ulcers, we make the following recommendations. For evaluating the outcome of interventions with a short-term follow-up (three months) in a clinical study we recommend the SF-MPQ and for 12-month follow-up in a clinical study the SF-36, with or without the SF-MPQ.