人体寰椎横韧带拉伸性能的实验研究

目的：研究人体寰椎横韧带的拉伸性能。方法：新鲜寰椎标本８例,制备成拉伸试件,进行定速率单向拉伸至横韧带断裂。结果：寰椎横韧带平均最大载荷为３１１．６Ｎ,最大变形量为６．０ｍｍ,刚度为７２．９Ｎ／ｍｍ。结论：寰椎侧块间的分离超过６．０ｍｍ,就可存在横韧带断裂。     

Internal models underlying grasp can be additively combined

Our ability to additively combine two learned internal models was investigated by studying the forces people generate when lifting objects with a precision grip. Subjects were required to alternately lift two objects of identical physical appearance but differing weight. Grip force scaling prior to lift-off was used to estimate the output of the internal model associated with each object. Appropriate internal models were formed when alternately lifting two objects of different weight. The objects were then combined by stacking them one upon the other, and the combined object was lifted. Results show that subjects can additively combine internal models of object dynamics but the sum is biased by a default estimate of the objects weight.     

A Simple Rheological Method for the in Vitro Assessment of Mucin-Polymer Bioadhesive Bond Strength

A simple viscometric method was used to quantify mucin-polymer bioadhesive bond strength. Viscosities of 15% (w/v) porcine gastric mucin dispersions in 0.1 N HC1 (pH 1) or 0.1 N acetate buffer (pH 5.5) were measured with a Brookfield viscometer in the absence (_m) or presence (_t) of selected neutral, anionic, and cationic polymers (0.1–2.5%, w/v). Viscosity components of bioadhesion (1%) were calculated from the equation, _t = _m + _p + _b, where _p is the viscosity of corresponding pure polymer solution as measured by an Ostwald viscometer. The forces of bioadhesion (F) were calculated from the equation, F = _b, where is the rate of shear/sec. _b's and F's for polyelectrolytes, e.g., polyacrylic acid, cationic gelatin, and chitosan were always higher in acetate buffer than in HC1. Validity of the technique and the effect of ionic charge, polymer conformation, and rate of shear on _b and F are discussed, as is a comparison of this method to other methods for evaluating bioadhesive materials.     

Bile Salt–Fatty Acid Mixed Micelles as Nasal Absorption Promoters of Peptides. I. Effects of Ionic Strength,Adjuvant Composition,and Lipid Structure on the Nasal Absorption of [D-Arg2]Kyotorphin

Bile salts and synthetic surfactants have been used to promote nasal absorption of peptide drugs. Although a marked increase in nasal absorption has been achieved, this may not be adequate and the possibility of adjuvant-induced membrane toxicity exists. The present study employs a rat in situ nasal perfusion technique and mixed micelles between sodium glycocholate (NaGC) and various lipids as potential nasal absorption enhancers of a stable model dipeptide, [D-Arg²]kyotorphin. NaGC alone enhanced the nasal absorption of the dipeptide in a concentration-dependent manner. When linoleic acid was added to form mixed micelles with NaGC, the absorption was further enhanced (P < 0.01). The effect of mixed micelles was synergistic and much greater than with single adjuvants. Increasing ionic strength was found to increase the adjuvant activity of both NaGC and NaGC–lipid mixed micelles. Structure of the lipid component of the mixed micelles also affected the adjuvant potency. Oleic acid, a cis-unsaturated fatty acid, was more effective than elaidic acid, the trans-isomer, whereas cis-linoleic acid and trans-linolelaidic acid were equally effective ( = 0.05). Mixed micelles of mono-glycerides such as monoolein and monolinolein were also more effective than NaGC alone ( = 0.05). Micellar solubilization of these polar lipids by NaGC appears to be important for nasal absorption enhancement to occur. Reversal of the membrane permeability was also observed within approximately 20–40 min after removal of the adjuvants from the rat nasal cavity. These observations are similar to the effects of mixed micelles on the rectal mucosa and may involve the same mechanism.     

上海市50岁及以上人群维生素D水平与握力的关联研究

目的 探讨上海市≥50岁人群维生素D水平与握力的关系。方法 数据来源于WHO全球老龄化与成人健康研究我国上海市2018-2019年数据,采用logistic回归模型分析维生素D水平与握力的关系,进一步按照性别、年龄及乳制品摄入情况进行分层;采用限制性立方样条曲线绘制维生素D水平与低握力的剂量-反应曲线。结果 共4 391人纳入研究,其中男性2 054人（46.8%）;年龄（67.02±8.81）岁;低握力1 421人（32.4%）;维生素D不足及缺乏分别为1 533人（34.9%）和401人（9.1%）。在调整相关混杂因素后,logistic回归分析结果显示,维生素D缺乏的人群发生低握力的风险更高（OR=1.41,95%CI：1.09~1.83）;在男性中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关（OR=1.67,95%CI：1.12~2.50）,而女性中两者之间无关联（OR=1.30,95%CI：0.97~1.74）;在60~69岁及≥80岁年龄组中,调整相关混杂因素后,维生素D缺乏与低握力发生风险呈显著正相关（OR=1.57,95%CI：1.05~2.35;OR=2.40,95%CI：1.08~5.31）,在乳制品摄入<250 ml/d的人群中,调整相关混杂因素后,二者之间呈显著正相关（OR=1.57,95%CI：1.17~2.09）,而在乳制品摄入≥250 ml/d的人群中无明显关联。限制性立方条样图显示,低握力的发生风险可能随维生素D含量的上升而降低,但差异无统计学意义（P>0.05）。结论 维生素D水平与握力存在一定的关系,维生素D缺乏人群出现低握力的风险更高。     

EMG Biofeedback as a Tool for Simulating the Effects of Specific Leg Muscle Weakness on a Lifting Task

This study investigated the use of EMG biofeedback to simulate weakened rectus femorii and gastrocnemii muscles during the performance of a lifting task. Eight healthy women performed 15 kg free-style lifts from floor level. Three conditions were tested: unconstrained lifting, lifting with rectus femorii activity volitionally limited bilaterally through EMG biofeedback to less than 45% of maximal EMG activity, and lifting with the gastrocnemii limited to a similar level. Limiting leg muscle activity through biofeedback led to an alteration of lifting strategy, with resulting performance variables (joint angles and torques, angular velocities, center of pressure excursion, and segment coordination) comparing favorably with those from lifting trials performed by six women with moderate leg muscle weaknesses. The data indicate that EMG biofeedback can be used to simulate the effects of leg muscle weakness during these lifts, providing a new tool to study the biomechanics of muscle weakness.     

后巩膜加固术对视网膜振荡电位的影响

目的　为了更进一步地了解后巩膜加固术治疗高度进行性近视的疗效和机理。方法　采用日本产Ｎｅｕｒｏｐａｃｋ Ｆｏｕｒ ４１０４ Ｋ 电生理仪,对２６ 例５２ 眼高度进行性近视行后巩膜加固术前、术后视网膜振荡电位进行定量分析。结果　术前、术后振荡电位总振幅经统计学处理有非常显著性差异,波的潜伏期无显著性差异。结论　本文认为后巩膜加固术可改善视网膜血液循环,并对机理进行了探讨     

枳椇子水提取液对小鼠综合体能的影响

目的：考察枳椇子水提取液对小鼠综合体能的影响。方法：小鼠随机分成两组：对照组和枳椇子水提取液组。枳椇子水提取液组按10g生药/kg体重／d，每日2次灌胃给药，共21天；对照组给予同体积饮用水。于末次给药后1h，分别测试两组小鼠的耐寒、耐热机能及抗疲劳能力。结果：枳椇子水提取液显著提高小鼠的耐寒、耐热机能并延长小鼠游泳、爬杆时间。结论：枳椇子水提取液具有增强小鼠综合体能的作用。     

离子强度对丙基甲基纤维素骨架片释药的影响

目的：探讨溶出介质的离子强度对难溶性药物的丙基甲基纤维素（HPMC）骨架片释药的影响。方法：以甲氧苄胺嘧啶、卡马西平、磺胺甲恶唑和茶碱4种难溶性药物为模型药物，测定5种不同离子强度介质（水、0．20％氯化钠溶液、0．50％氯化钠溶液、0．90％氯化钠溶液和1．80％氯化钠溶液）下的药物释放度和溶出参数。结果：难溶性药物的HPMC骨架片释药随着其溶出介质离子强度的增加而减慢。结论：释药速率与离子强度之间存在较好的线性负相关关系。     

Genetic Variations in Bone Density, Histomorphometry, and Strength in Mice

The purpose of this study was to assess breed-related differences in bone histomorphometry, bone biomechanics, and serum biochemistry in three mouse breeds shown to differ in bone mineral density (BMD) (as measured by DXA) and bone mineral content (BMC). Femurs, tibiae, and sera were collected from 16-week-old C3H/HeJ {C3H}, C57BL/6J {BL6}, and DBA/2J {DBA}mice (n = 12/breed). Data collected included BMC and BMD (femora), histomorphometry of cancellous (distal femur) and cortical bone (diaphyseal tibiae and femora), bone strength (femora), and serum alkaline phosphatase (ALP). Consistent with previous reports, BMC and BMD were higher in C3H than in BL6 or DBA mice. The higher BMD in the C3H breed was associated with greater cancellous bone volume, cortical bone area, periosteal bone formation rate, biomechanical strength, and serum ALP. However, mid-diaphyseal total femoral and tibial cross-sectional area and moment of inertia were greatest in BL6, intermediate in C3H, and lowest in DBA mice. The specific distribution of cortical bone in C3H, BL6, DBA mice represents a difference in adaptive response to similar mechanical loads in these breeds. This difference in adaptive response may be intrinsic to the adaptive mechanism, or may be intrinsic to the bone tissue material properties. In either case, the bone-adaptive response to ordinary mechanical loads in the BL6 mice yields bones of lower mechanical efficiency (less stiffness per unit mass of bone tissue) and does not adapt as well as that of the C3H mice where the final product is a bone with greater resistance to bending under load. We suggest that the size, shape, and BMD of the bone are a result of breed-specific genetically regulated cellular mechanisms. Compared with the C3H mice, the lower BMD in BL6 mice is associated with long bones that are weaker because the larger cross-sectional area fails to compensate completely for their lower BMD and BMC. Received: 16 November 1999 / Accepted: 19 April 2000 / Online publication: 27 July 2000