神经肽DGAVP和Org2766对神经细胞内游离Ca2+的影响

运用Ca²⁺指示剂Fura-2作为细胞内钙离子的荧光探针,利用AR—CM—MIC阳离子测定系统,检测了分离的神经细胞内游离钙及其变化,并观测了DGAVP和Org2766对蛋白质合成抑制剂茴香霉素(ANI)引起细胞内钙离子浓度([Ca²⁺]_i)变化的影响。结果表明茴香霉素可使[Ca²⁺]_i显著升高,且有量效关系;DGAVP本身并不引起[Ca²⁺]_i发生显著变化,但适当剂量的DGAVP可显著对抗一定剂量范围内ANI升高[Ca²⁺]_i的作用,提示DGAVP对抗ANI的蛋白质合成抑制效应可能是通过拮抗ANI升高[Ca²⁺]_i这一途径实现的,另一神经肽Org2766则可能不是通过这一机制发生作用。从细胞内Ca²⁺的角度看,这两种肽的作用机理显然是不同的。     

Inertial properties of the human trunk of males determined from magnetic resonance imaging

The purpose of this study was to evaluate the segmental parameters of the human trunk of malesin vivo using magnetic resonance imaging (MRI). In addition, the efficacy of volumetric estimation and existing prediction formulas to produce segmental properties similar to those produced by MRI was evaluated. As opposed to finding one representative normal value for these parameters, a range of normal values was defined. For instance, the average trunk mass was 42.2%±3.5% (x±SD) of body mass, but values ranged from 35.8% to 48.0%. To account for segment parameters more accurately, specific anthropometric measures need to be considered in addition to overall measures of body height and mass. These specific measures included segment length, circumference, width, and depth. Studies reporting general percentages based on height and/or mass were found to be inadequate predictors of segmental parameters of the trunk compared with MRI estimates. Volumebased estimates, which assume a uniform density distribution within a segment, were found to correspond closely to MRI values except for the thorax. However, the use of density values reflective of the livingin vivo state would likely alleviate this disparity, thus indicating that the volumetric technique may be effective for deriving segmental parameters for large segments of the trunk. Future research should adopt noninvasive techniques such as MRI and/or volumetric estimation to enhance the predictability of segmental parameters of the body for specific population groups characterized by gender, developmental age, body type, and fitness level. Further efforts should be made to establish standardized boundary definitions for trunk segments to avoid unnecessary confusion, from which substantial errors may be introduced into biomechanical linked-segment analyses of human movement.