Postural Sway during Local Vibratory Stimulation for Proprioception in Elderly Individuals with Pre-Sarcopenia

Objective: Many studies have demonstrated that the loss of muscle mass (LMM) poses a risk of postural instability in the elderly; however, few studies have shown how LMM decreases proprioception. In this study, we investigated the changes in postural sway among older individuals with LMM induced by application of a local vibratory stimulus. Method: We enrolled 64 older adults (mean age). Postural sway was measured while applying vibration stimuli of 30, 60, and 240 Hz to both the gastrocnemius and lumbar multifidus muscles. We also measured the relative proprioceptive weighting ratio (RPW) of postural sway. The patients were divided into LMM and non-LMM (NLMM) groups. The study subjects were compared in terms of their age, height, weight, body mass index (BMI), lower leg skeletal muscle mass index (LSMI), L4/5 lumbar multifidus cross-sectional area ratio, and RPW at 30, 60, and 240 Hz. Results: Subjects in the LMM group showed a significantly lower RPW at 60 Hz, LSMI, and BMI than did those in the NLMM group. Conclusions: Decrease in RPW with 60-Hz stimulation concerning the lower leg proprioception is a risk factor for LMM-associated postural instability in the elderly. Consequently, with respect to the gastrocnemius muscles proprioception in LMM, it is necessary to perform assessments using muscle spindle stimuli.     

Recovery process of respiratory muscle strength in patients following stroke: A Pilot Study

Objective: To determine the recovery process of respiratory muscle strength during 3 months following stroke, and to investigate the association of change in respiratory muscle strength and physical functions. Additionally, we compared respiratory muscle strength with those of healthy subjects. Method: In this prospective, observational study, 19 stroke patients and 19 healthy subjects were enrolled. Maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), motricity index, trunk control test, 6-minute walk test (6MWT) and functional independence measure were assessed at 1, 2, and 3 months from stroke onset in stroke patients. MIP and MEP were assessed at arbitrary times in healthy subjects. Repeated one-way analysis of variance with Bonferroni post-hoc test was used to compare the change in respiratory muscle strength in each period in stroke patients. Pearson''s correlation coefficient was computed for changes in respiratory muscle strength and physical functions. Student''s t-test was used to compare respiratory muscle strength between stroke patients at 3 months from onset and healthy subjects. Results: MIP was significantly increased at 3 months compared to 1 month. MEP was significantly increased in 2 months and 3 months, compared to 1 month. MIP changes associated with 6MWT changes. Compared to healthy subjects, MIP and MEP at 3 months were significantly lower in stroke patients. Conclusion: Respiratory muscle strength significantly increased during 3 months following stroke. However, the trend of recovery may be different. MIP changes may associated with walking endurance changes. During 3 months following stroke, respiratory muscle strength did not recover to healthy subjects.     

丝素蛋白修饰改性的聚羟基脂肪酸酯支架上人体平滑肌细胞的生长

聚三羟基丁酸脂和聚三羟基己酸脂的共聚物(PHBHH_x)是一种具有良好强度和韧性的生物可降解高分子材料, 可作为组织工程心脏瓣膜支架的选择材料之一. 但其生物相容性尚不甚理想. 为此, 本工作利用丝素蛋白修饰改性高分子多孔支架, 以提高支架的生物相容性. 并将人体平滑肌细胞接种在该复合支架上进行体外培养, 以证实改性效果. 其中, 用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐(MTT)方法测试细胞生长, 评估复合支架的细胞相容性. 并用扫描电子显微镜观察细胞在支架上的生长形态. 结果显示, 丝素蛋白修饰改性后的复合支架更有利于细胞的粘附与生长, 平滑肌细胞在支架上表现出良好的生长形态. 这表明, 丝素能够改善多孔支架的生物相容性, 使PHBHH_x/丝素蛋白复合物能更适宜作为组织工程心脏瓣膜的支架材料. 结果对于进一步研究细胞外间质在复合支架上的生长以及体外培养的组织重建有重要的参考意义.     

用反相高效液相色谱法测定小鼠心肌、骨骼肌中AT P、AD P和AM P的含量

采用反相高效液相色谱法同时测定小鼠心肌、骨骼肌组织中ATP(三磷酸腺苷 )、ADP(二磷酸腺苷 )、AMP(一磷酸腺苷 )的含量。以150mmol/L磷酸二氢钾缓冲液 (pH=6.25)为流动相 ,采用BDShypersilC18 不锈钢色谱柱 ,紫外检测波长为254nm ,线性范围为1～200mg/L。ATP、ADP和AMP的平均加标回收率均在90 %以上 ,检出限分别为10ng、10ng、15ng。该法灵敏、准确 ,试剂费用低。     

心肌细胞膜ATP酶活性在线测定及变化规律研究

基于流动注射停流技术和软物质在线采集技术建立了一种快速磷钼染色法测定细胞膜三磷酸酰苷(ATP)酶活性的方法.与传统方法相比,该分析方法速度提高了7倍,而且操作简便,试剂消耗少.将该方法应用于兔心肌细胞膜ATP酶活性变化规律的研究,结果显示酶活性在研究时间内按一定规律递减.为细胞膜及其受体的纯度、活性等相关研究提供了重要信息.     

反相高效液相色谱／质谱法同时测定鸡肉中5种喹诺酮药物残留

采用反相高效液相色谱／四级杆串联质谱（RP-HPLC／MS／MS）同时测定鸡肉中的5种喹诺酮药物（quinolones，QNs）。均质后的鸡肉样品采用磷酸盐缓冲溶液和乙腈的混和溶液提取。提取液经正己烷液-液分配（LLP）去除脂肪后，用C18固相萃取（SPE）柱净化，氨化甲醇洗脱，洗脱液用氮气吹干，流动相定容后，分析物采用LC／MS／MS电喷雾电离（ESI），正离子，多反应监测（MRM）模式检测，外标法定量。在添加浓度2．5～10μg/kg范围内，5种QNs的回收率在79．8％～95．1％之间；相对标准偏差（RSD）均小于11．7％。环丙沙星、丹诺沙星、恩诺沙星检出限（LOD）为0．5μg／kg，沙托沙星为1．0μg／kg，氟甲喹为0．1μg／kg。     

HPLC of phenylthiocarbamyol labelled uridine-diphosphate-hexosamine

Summary The biochemical functions of uridine-diphosphate-amino-sugar conjugates are largely unknown. As a first step to investigate their biological roles in glycolysis of higher organisms, bovine heart muscle, which metabolizes large quantities of glycogen, was assayed for uridine-diphosphate-hexosamine. A low molecular mass ultrafiltrate was prepared from the methanolsoluble fraction of a beef heart homogenate, and the fraction was further purified using anion-exchange and reverse-phase HPLC. Samples were analyzed by two HPLC methods; anion-exchange in borate buffer and reverse-phase ion-pair chromatography. One newly established technique employing phenylthiocarbamoyl labelled uridine-diphosphate-hexosamine also was used selectively to separate uridine-diphosphate-hexosamine from other uridine-diphosphate-sugars. Hydrolysate of purified sample was classified further according to molecular structure. As a result, phenylthiocarbamoyl labelled HPLC is suitable and easy for the detection of uridine-diphosphate-hexosamine and its derivatives.     

Gradient-enhanced FAWSETS perfusion measurements

This work describes the use of custom-built gradients to enhance skeletal muscle perfusion measurements acquired with a previously described arterial spin labeling technique known as FAWSETS (flow-driven arterial water stimulation with elimination of tissue signal). Custom-built gradients provide active control of the static magnetic field gradient on which FAWSETS relies for labeling. This allows selective, 180 degrees modulations of the phase of the perfusion component of the signal. Phase cycling can then be implemented to eliminate all extraneous components leaving a signal that exclusively reflects capillary-level perfusion. Gradient-enhancement substantially reduces acquisition time and eliminates the need to acquire an ischemic signal to quantify perfusion. This removes critical obstacles to application of FAWSETS in organs other than skeletal muscle and makes the measurements more desirable for clinical environments. The basic physical principles of gradient-enhancement are demonstrated in flow phantom experiments and in vivo utility is demonstrated in rat hind limb during stimulated exercise.     

Epoxy-based electroactive polymer gels

We describe a new type of electroactive polymer gel. In contrast to cross-linked polyacrylates, this system is based on triepoxides cross-linked with polyfunctional amines. The stoichiometry is selected to form a cross-linked gel with excess amino hydrogens. In acid solutions these become cationic and the ionic interactions cause the gel to swell. We describe the mechanical properties of the gels, their response to changes in pH and to electrical activation. The response time is in rough agreement with what would be expected for a diffusional process through a gel of this size (about 100 μm). Samples of smaller dimensions would be expected to respond more rapidly.     

Quenching of Myosin Intrinsic Fluorescence Unravels the Existence of a High Affinity Binding Site for Decavanadate

Decavanadate, one of the aggregated species of vanadate, is a potent inhibitor of several enzymes, including skeletal muscle myosin. However, its putative binding sites in myosin are largely unknown. Titration of the intrinsic fluorescence of myosin, purified from rabbit skeletal muscle, have been carried out in 0.3 M KCl, 5 mM CaCl₂ and 25 mM Tris-HCl (pH 7.0), with 0.1 mg/ml myosin. In the 0-200 M total vanadate concentration range, decavanadate produced approximately 25% quenching of the intrinsic fluorescence of myosin, with an apparent dissociation constant in the micromolar range. This effect was found to be specific of decavanadate, because titration with metavanadate up to 200 M did not produce a significant quenching of the intrinsic fluorescence of myosin. This quenching was accompanied by a parallel decrease of the accessibility of myosin tryptophans to the water-soluble collisional quencher KI, with an apparent dissociation constant also in the micromolar range. It is concluded that the binding of decavanadate to high-affinity sites in myosin produces local conformational change(s) near the tryptophans more accessible to water in the three-dimensional structure of this protein.