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111.
Morphological and electrophysiological properties of neural cells are substantially influenced by their immediate extracellular surroundings, yet the features of this environment are difficult to mimic in vitro. Therefore, there is a tremendous need to develop a new generation of culture systems that more closely model the complexity of nervous tissue. To this end, we engineered novel electrophysiologically active 3D neural constructs composed of neurons and astrocytes within a bioactive extracellular matrix-based scaffold. Neurons within these constructs exhibited extensive 3D neurite outgrowth, expressed mature neuron-specific cytoskeletal proteins, and remained viable for several weeks. Moreover, neurons assumed complex 3D morphologies with rich neurite arborization and clear indications of network connectivity, including synaptic junctures. Furthermore, we modified whole-cell patch clamp techniques to permit electrophysiological probing of neurons deep within the 3D constructs, revealing that these neurons displayed both spontaneous and evoked electrophysiological action potentials and exhibited functional synapse formation and network properties. This is the first report of individual patch clamp recordings of neurons deep within 3D scaffolds. These tissue engineered cellular constructs provide an innovative platform for neurobiological and electrophysiological investigations, serving as an important step towards the development of more physiologically relevant neural tissue models.  相似文献   
112.
There remains controversy as to the most accurate method ofpredicting ovulation for the timing of donor insemination. Ina prospective study based at a tertiary referral donor inseminationclinic we have assessed the ability of a urinary luteinizinghormone (LH) kit combined with vaginal ultrasonography to predictovulation for donor insemination. A total of 25 natural cycleswere monitored from the first day of the LH surge (detectedby the urinary kit). Daily transvaginal sonographic measurementof follicular size and endometrial thickness were used to predictovulation; monitoring continued until post-ovulatory changeswere seen. Transvaginal sonography combined with a urinary LHkit successfully predicted all those women who ovulated (20/25)and detected unfavourable conditions for insemination in theremaining 20% (5/25). In conclusion, where available transvaginalsonography combined with a urinary LH kit should be the methodof choice for timing donor insemination.  相似文献   
113.
Summary— Cholesteryl esters in the hydrophobic core of low-density lipoprotein (LDL) particles constitute a major molecular target during copper-mediated oxidation. To facilitate the rapid analysis and quantitation of the oxidative degradation of LDL cholesteryl esters, we describe a new approach based on light scattering detection following separation by HPLC. We have applied this approach to the evaluation of the protective capacity of a new synthetic antioxidant, S20478, during oxidation of LDL in the presence of copper ions. HPLC separation of cholesterol and the four major molecular species of cholesteryl esters (C16:0, C18:1, C18:2 and C20:4) of LDL was achieved in a single run of 20 min with high sensitivity (50 ng) and low background. Time course studies of the oxidative modification of LDL (ratio LDL protein: copper, 100 μg/mL: 1μM) revealed that the content of unsaturated cholesteryl esters (C20:4 and C18:2) decreased (–30% and –15%, respectively) within 90 min of copper-mediated oxidation, while only minor degradation (up to 15%) of monounsaturated (C18:1) and saturated (C16:0) esters occurred. At 24 hours of oxidation, only traces (< 5%) of the C20:4 and C18:2 esters were detectable; whereas 52% of the C18:1 ester remained (P < 0.01). Of the saturated esters, only minor proportions (35% or less) underwent oxidative modification. In addition, some 81% of free cholesterol was conserved as the native sterol. The synthetic antioxidant, S20478 (50 μM) was capable of inhibiting the initiation and the propagation of copper-mediated LDL oxidation as determined by the time- and dose-dependant inhibition of the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the conservation of the net electrical charge of LDL; indeed S20478 conserved cholesteryl esters in their native form up to 24 hours. However, after prolonged exposure to copper ions (48 hours), only 47% of the unsaturated esters remained (C18:2, P < 0.05). Nonetheless, S20478 (10 μM) was more efficient in inhibiting copper-mediated LDL oxidation as compared to probucol at the same concentration. These findings suggest that S20478 may be of potential interest in a new antioxidant approach to therapeutic stabilisation and regression of atherosclerotic plaques. Moreover, this method should prove useful in the assessment of the integrity of native LDL, and provides a new chemical marker of the degree of LDL oxidation.  相似文献   
114.
1. Ouabain is known to have natriuretic effects only at high doses, and therefore if endogenously produced ouabain has a role in the regulation of sodium excretion, the renal response to ouabain must be increased substantially in certain physiological situations. The aim of this study is to determine whether treatment with the mineralocorticoid, aldosterone, potentiates that natriuretic response to ouabain. 2. Six conscious sheep received renal arterial infusion of either vehicle or aldosterone (3 μg/h). Forty hours after commencement of infusion ouabain was infused into the renal artery at 400 μg/h for 60min. A second infusion of ouabain was administered on the 6th day of aldosterone treatment. 3. In the absence of aldosterone, the effects on sodium excretion produced by ouabain infusion at 400 μg/h into the renal artery were variable and not statistically significant. Ouabain infusion after 40 h of aldosterone treatment increased sodium excretion from 40 ± 14 to 676 ± 69 μmol/min in the second hour following cessation of ouabain infusion (P< 0.001). Ouabain infusion after 6 days of aldosterone treatment increased sodium excretion similarly. Ouabain-stimulated sodium excretion was significantly greater during aldosterone treatment compared to vehicle treatment (P<0.05). In contrast, no enhancement of effect was observed after acute treatment with aldosterone. 4. These results demonstrate potentiation of the natriuretic response to ouabain infusion by chronic mineralocorticoid treatment and suggest a potential role of endogenous digitalislike factor in the physiological control of sodium homeo stasisaldo sterone, endogenous digitalis-like factor, ouabain, sodium excretion.  相似文献   
115.
人工神经元网络用于复方氯丙嗪的含量测定   总被引:9,自引:0,他引:9  
将误差反向传播(BP)的人工神经元网络(ANN)模型,用于复方氯丙嗪紫外重叠光谱分 析。对ANN模型的参数进行了优化。采用f(x)二1/(1+e-x)作为网络节点的输入输出转换函数的三 层神经网络具有较佳性能,当取隐含节点数为15时,该网络预测结果的最小平均相对误差为1.22%, 将研制的ANN模型用于复方氯丙嗪含量测定,其结果与药品标准法和偏最小二乘法(PLs)一致。  相似文献   
116.
庆大霉素在小鼠的时辰毒性及时辰药代动力学   总被引:1,自引:0,他引:1  
宋建国 《药学学报》1991,26(6):401-405
本文研究了庆大霉素对小鼠的毒性及其药代动力学的昼夜节律性变化。雄性ICR小鼠自实验前两周置于标准的明期和暗期下饲养,自由进食进水。毒性实验剂量为庆大霉素290mg/kg,Sc:药代动力学实验剂量为45 mg/kg,Sc。结果表明,庆大霉素毒性及药代动力学因用药时间不同呈明显的昼夜节律性变化。明期中点用药毒性最大,血药浓度最高,AUC值最大:暗期用药毒性小,血药浓度低,AUC值小。提示了庆大霉素毒性的昼夜节律变化与其药代动力学的的昼夜节律变化有密切关系。  相似文献   
117.
吡唑烷酮类化合物的抗惊厥作用   总被引:2,自引:0,他引:2  
对3类14种吡唑烷酮类化合物的抗惊厥作用进行了比较研究,它们对最大电休克惊厥均有对抗作用,作用出现快,但维持时间较短,其中II-f作用最强,对听源性发作和家兔海马注射硫酸锌形成的慢性癫痫模型也有效。此外,III-类尚能对抗戊四唑引起的阵挛性惊厥。  相似文献   
118.
Legitimizing surrogacy in Israel   总被引:3,自引:2,他引:1  
Recently the Israeli Parliament passed legislation regarding all aspects of assisted reproductive techniques, including surrogacy. The main points of this legislation are presented and discussed. The most important aspects are: (i) a public committee authorizes and supervises every single case; (ii) only full surrogacy is permitted; (iii) the agreement is not commercial, reasonable expenses can be paid to the surrogate mother under the supervision of the Approving Committee; (iv) the surrogate mother must be single or divorced; (v) under certain conditions the surrogate mother can withdraw from the agreement; (vi) the child is under the tutelage of a social worker, representing the state, from birth until the completion of the adoption procedure. The religious, social and legal status of surrogate pregnancies worldwide are discussed.   相似文献   
119.
烯丙胺类抗真菌药物比较分子力场分析(CoMFA)的研究   总被引:1,自引:0,他引:1  
本实验采用“活性类似物法”确定了烯丙胺类抗真菌化合物的药效构象,采用比较分子力场分析法(CoMFA)拟合了48个烯丙胺类抗真菌化合物对6种常见致病真菌的3D-QSAR方程,并比较了2种不同叠合规则对模型的影响,最后,用5个新合成化合物对所拟合的抗石膏样毛癣菌、抗烟曲霉菌的CoMFA模型的预测能力进行了检验,得到比较满意的结果。  相似文献   
120.
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