Injectable hybrid inorganic nanoscaffold as rapid stem cell assembly template for cartilage repair     

Shenqiang Wang  Letao Yang  Bolei Cai  Fuwei Liu  Yannan Hou  Hua Zheng  Fang Cheng  Hepeng Zhang  Le Wang  Xiaoyi Wang  Qianxin Lv  Liang Kong  Ki-Bum Lee  Qiuyu Zhang 《国家科学评论(英文版)》2022,9(4)

Cartilage injuries are often devastating and most cannot be cured because of the intrinsically low regenerative capacity of cartilage tissues. Although stem-cell therapy has shown enormous potential for cartilage repair, the therapeutic outcome has been restricted by low survival rates and poor chondrocyte differentiation in vivo. Here, we report an injectable hybrid inorganic (IHI) nanoscaffold that facilitates fast assembly, enhances survival and regulates chondrogenic differentiation of stem cells. IHI nanoscaffolds that strongly bind to extracellular matrix (ECM) proteins assemble stem cells through synergistic 3D cell–cell and cell–matrix interactions, creating a favorable physical microenvironment for stem-cell survival and differentiation in vitro and in vivo. Additionally, chondrogenic factors can be loaded into nanoscaffolds with a high capacity, which allows deep, homogenous drug delivery into assembled 3D stem-cell-derived tissues for effective control over the soluble microenvironment of stem cells. The developed IHI nanoscaffolds that assemble with stem cells are injectable. They also scavenge reactive oxygen species and timely biodegrade for proper integration into injured cartilage tissues. Implantation of stem-cell-assembled IHI nanoscaffolds into injured cartilage results in accelerated tissue regeneration and functional recovery. By establishing our IHI nanoscaffold-templated 3D stem-cell assembly method, we provide a promising approach to better overcoming the inhibitory microenvironment associated with cartilage injuries and to advance current stem-cell-based tissue engineering.  相似文献   

反者道之动(2本)——后现代主义思潮与教育     

李永全 《和田师范专科学校学报》2006,26(2):1-3

从后现代主义的起源、流变及其表现形式来看,后现代主义思潮具有反传统、反理性、多元化、自组织等特征.这种思潮已经波及科学及教育领域,正在并将继续对教育科学的理论及实战产生诸多正面、负面的影响.  相似文献   

体力活动与癌症生存研究的10大问题     

Kerry S. Courney  Laura Q. Rogers  Kristin L. Campbell  Jeff K. Vallance  Christine M. Friedenreich 《北京体育大学学报》2016,39(2):40-48

摘要：今天的美国有1 400万的癌症存活者,其中的很多存活者中都接受了多种治疗,包括手术、放疗、化疗、靶向治疗等。这些治疗能够延长生存时间,但同时也会带来很多急慢性的副作用,危害健康,影响生活质量。体力活动（PA）与癌症生存这一领域发展迅速,主要研究PA对癌症患者的影响。基于该领域的研究进展,提出了以下10大研究问题：1）PA能够降低癌症复发风险、和/或提高存活吗？2）PA能够影响癌症治疗决策、完成率、和/或患者对治疗的反应吗？3）癌症存活者的最佳运动处方是什么？4）静坐少动行为对癌症存活者有何影响？5）癌症存活者最有效的体力活动干预方案是什么？6）哪些癌症会影响病人对PA的反应？7）癌症存活者进行体力活动时需要注意的安全问题有哪些？8）哪些具体的癌症症状可以由PA解决？9）对于癌症晚期患者,体力活动还有何作用？10）如何将体力活动研究结果转化到临床和社区肿瘤实践中来？上述问题的回答至关重要,这不仅关系到体力活动和癌症存活这一研究领域的发展,更重要的是,能够为每年数百万新诊断为癌症的病人、正在接受癌症治疗的病人、治疗结束处于恢复中的病人或是那些正在与晚期癌症抗争的病人带来福音。  相似文献   

The influence of lower limb amputation level on the approach in the amputee long jump     

Nolan L  Lees A 《Journal of sports sciences》2007,25(4):393-401

In this study, we investigated the adjustments to posture, kinematic and temporal characteristics of performance made by lower limb amputees during the last few strides in preparation for long jump take-off. Six male unilateral trans-femoral and seven male unilateral trans-tibial amputees competing in a World Championships final were filmed in the sagittal plane using a 100-Hz digital video camera positioned so that the last three strides to take-off were visible. After digitizing using a nine-segment model, a range of kinematic variables were computed to define technique characteristics. Both the trans-femoral and trans-tibial athletes appeared to achieve their reduction in centre of mass during the flight phase between strides, and did so mainly by extending the flight time by increasing stride length, achieved by a greater flexion of the hip joint of the touch-down leg. The trans-tibial athletes appeared to adopt a technique similar to that previously reported for able-bodied athletes. They lowered their centre of mass most on their second last stride (-1.6% of body height compared with -1.4% on the last stride) and used a flexed knee at take-off on the last stride, but they were less able to control their downward velocity at touch-down (-0.4 m x s(-1)). Both this and their restricted approach speed (8.9 m x s(-1) at touch-down), rather than technique limitations, influenced their jump performance. The trans-femoral athletes lowered their centre of mass most on the last stride (-2.3% of body height compared with -1.6% on the second last stride) and, as they were unable to flex their prosthetic knee sufficiently, achieved this by abducting their prosthetic leg during the support phase, which led to a large downward velocity at touch-down (-0.6 m x s(-1)). This, combined with their slower approach velocity (7.1 m x s(-1) at touch-down), restricted their performance.  相似文献   

Perceived importance of components of asynchronous music during circuit training     

Crust L 《Journal of sports sciences》2008,26(14):1547-1555

This study examined regular exercisers' perceptions of specific components of music during circuit training. Twenty-four men (38.8 years, s = 11.8 years) and 31 women (32.4 years, s = 9.6 years) completed two questionnaires immediately after a circuit training class. Participants rated the importance of 13 components of music (rhythm, melody, etc.) in relation to exercise enjoyment, and each completed the "Affect Intensity Measure" (Larsen, 1984, Dissertation Abstracts International, 5, 2297B. (University microfilms No. 84-22112)) to measure emotional reactivity. Independent t-tests were used to evaluate gender differences in perceptions of musical importance. Pearson correlations were computed to evaluate the relationships between affect intensity, age and importance of musical components. Consistent with previous research and theoretical predictions, rhythm response components (rhythm, tempo, beat) were rated as most important. Women rated the importance of melody significantly higher than did men, whereas men gave more importance to music associated with sport. Affect intensity was found to be positively and significantly related to the perceived importance of melody, lyrical content, musical style, personal associations and emotional content. Results suggest that exercise leaders need to be sensitive to personal factors when choosing music to accompany exercise. Qualitative research that focuses on the personal meaning of music is encouraged.  相似文献   

Self-efficacy and outcome expectancy in beginning weight training class: their relations to students' behavioral intention and actual behavior     

Gao Z  Xiang P  Lee AM  Harrison L 《Research quarterly for exercise and sport》2008,79(1):92-100

This study was an initial attempt to investigate the relationships among self-efficacy, outcome expectancy, behavioral intention, and actual behavior over time in a beginning weight training class. A total of 109 participants completed questionnaires assessing their self-efficacy, outcome expectancy, and intentions for future weight training. Their attendance and workout logs were calculated as a measure of actual behavior. Correlation analyses revealed significant positive relationships among all the variables during both program periods. Multiple regression analyses indicated that outcome expectancy initially played a more important role than self-efficacy in predicting behavioral intention and actual behavior. However, self-efficacy appeared more influential at midprogram. Findings of this study can enhance our understanding of the determining factors for individuals' motivated behaviors in college physical activity classes.  相似文献   

Relationships among values, achievement orientations, and attitudes in youth sport   总被引：1，自引：0，他引：1  

Lee MJ  Whitehead J  Ntoumanis N  Hatzigeorgiadis A 《运动与训练心理学杂志》2008,30(5):588-610

This research examines the value-expressive function of attitudes and achievement goal theory in predicting moral attitudes. In Study 1, the Youth Sport Values Questionnaire (YSVQ; Lee, Whitehead, & Balchin, 2000) was modified to measure moral, competence, and status values. In Study 2, structural equation modeling on data from 549 competitors (317 males, 232 females) aged 12-15 years showed that moral and competence values predicted prosocial attitudes, whereas moral (negatively) and status values (positively) predicted antisocial attitudes. Competence and status values predicted task and ego orientation, respectively, and task and ego orientation partially mediated the effect of competence values on prosocial attitudes and of status values on antisocial attitudes, respectively. The role of sport values is discussed, and new research directions are proposed.  相似文献   

Maximizing recovery time between knock-out races improves sprint cross-country skiing performance     

Kerry McGawley  Coline Van Waerbeke  Karl-Johan Westberg  Erik P.Andersson 《运动与健康科学(英文)》2022,11(1):21-29

Background:In a sprint cross-country(XC)ski competition,the difference in recovery times separating the first and the second semi-final(SF)heats from the final(F)may affect performance.The aim of the current study was to compare the effects of longer vs.shorter recovery periods prescribed between the 3 knock-out races of a simulated sprint XC ski competition involving a prologue(P),quarter-final(QF),SF,and F.Methods:Eleven well-trained XC ski athletes completed 2 simulated sprint XC ski competitions on a treadmill involving 4×883-m roller-ski bouts at a 4°incline using the gear 3 ski-skating sub-technique.The first 3 bouts were completed at a fixed speed(PFIX,QFFIX,and SFFIX)corresponding to~96%of each individual’s previously determined maximal effort.The final bout was performed as a self-paced sprint time trial(FSTT).Test conditions differed by the time durations prescribed between the QFFIX,SFFIX,and FSTT,which simulated real-world XC ski competition conditions using maximum(MAX-REC)or minimum(MIN-REC)recovery periods.Results:The FSTT was completed 5.4±5.5 s faster(p=0.009)during MAX-REC(179.2±18.1 s)compared to MIN-REC(184.6±20.0 s),and this was linked to a significantly higher power output(p=0.010)and total metabolic rate(p=0.009).The pre FSTT blood lactate(BLa)concentration was significantly lower during MAX-REC compared to MIN-REC(2.5±0.8 mmol/L vs.3.6±1.6 mmol/L,respectively;p=0.027),and the pre-to-post FSTT increase in BLa was greater(8.8±2.1 mmol/L vs.7.1±2.3 mmol/L,respectively;p=0.024).No other differences for MAX-REC vs.MIN-REC reached significance(p>0.05).Conclusion:Performance in a group of well-trained XC skiers is negatively affected when recovery times between sprint heats are minimized which,in competition conditions,would occur when selecting the last QF heat.This result is combined with a higher pre-race BLa concentration and a reduced rise in BLa concentration under shorter recovery conditions.These findings may help inform decision making when XC skiers are faced with selecting a QF heat within a sprint competition.  相似文献   

Kicking modality during erratic-dynamic and static condition effects the muscular co-activation of attacker     

Tae-Whan Kim  Sang-Cheol Lee  Se-Kee Kil  Sung-Chul Kang  Young-Tae Lim 《Journal of sports sciences》2017,35(9):835-841

The purpose of the study was to investigate the effect of different kicking modality, i.e., erratic-dynamic target (EDT) versus static target (ST) on the performance of the roundhouse kick in two groups of taekwondo athletes of different skill level. Three-dimensional analysis and surface electromyography (SEMG) analysis were performed on 12 (Group A: six sub-elite, Group B: six elite) athletes to investigate muscle co-activation pattern under two conditions, i.e., EDT versus ST. In the results, the muscle recruitment ratio of the agonistic muscles was higher for Group A, whereas Group B had higher recruitment ratio for antagonist muscles. Overall, the co-activation index (CI) of hip joints appeared higher in the extensors for Group A, whereas higher CI was observed in flexor muscles for Group B with comparatively higher CI during EDT condition than ST condition. Higher value of CI was observed in flexor muscles of the knee joints among Group A during EDT conditions, in contrast, higher CI in the extensor muscles was observed among Group B during ST conditions. In conclusion, the study confirmed that erratic-dynamic movements of target could change the movement coordination pattern to maintain the joint stability of participants.  相似文献   

Performing under pressure: Exploring the psychological state underlying clutch performance in sport     

Christian Swann  Lee Crust  Patricia Jackman  Stewart A. Vella  Mark S. Allen  Richard Keegan 《Journal of sports sciences》2017,35(23):2272-2280

Clutch performance is improved performance under pressure. However, little research has examined the psychological state experienced by athletes in these situations. Therefore, this study qualitatively examined the subjective experience underlying clutch performance across a range of sports (e.g., team, individual) and standards (Olympic to recreational athletes). Sixteen athletes (M_age = 27.08 years; SD = 6.48) took part in in-depth, semi-structured interviews primarily after an exceptional performance (M = 4.38 days later; SD = 3.14). Data were analysed inductively and thematically. Clutch states involved 12 characteristics, including heightened and deliberate concentration, intense effort, and heightened awareness, which distinguished the experience of clutch from other optimal psychological states such as flow. Other characteristics, such as perceptions of control, were also reported and supported previous experimental research on clutch. These findings present in-depth qualitative insights into the psychological state underlying clutch performance, and are discussed in relation to the existing literature on optimal psychological states in sport.  相似文献