The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte ...The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte mechanotransduction remain poorly understood. We've previously shown that osteocyte mechanosensitivity is encoded through unique intracellular calcium (Ca^(2+) ) dynamics. Here, by simultaneously monitoring Ca^(2+) and actin dynamics in single cells exposed to fluid shear flow, we detected actin network contractions immediately upon onset of flow-induced Ca^(2+) transients, which were facilitated by smooth muscle myosin and further confirmed in native osteocytes ex vivo. Actomyosin contractions have been linked to the secretion of extracellular vesicles(EVs), and our studies demonstrate that mechanical stimulation upregulates EV production in osteocytes through immunostaining for the secretory vesicle marker Lysosomal-associated membrane protein 1(LAMP1) and quantifying EV release in conditioned medium, both of which are blunted when Ca^(2+) signaling was inhibited by neomycin. Axial tibia compression was used to induce anabolic bone formation responses in mice, revealing upregulated LAMP1 and expected downregulation of sclerostin in vivo. This load-related increase in LAMP1 expression was inhibited in neomycin-injected mice compared to vehicle.Micro-computed tomography revealed significant load-related increases in both trabecular bone volume fraction and cortical thickness after two weeks of loading, which were blunted by neomycin treatment. In summary, we found mechanical stimulation of osteocytes activates Ca^(2+) -dependent contractions and enhances the production and release of EVs containing bone regulatory proteins. Further, blocking Ca^(2+) signaling significantly attenuates adaptation to mechanical loading in vivo, suggesting a critical role for Ca^(2+) -mediated signaling in bone adaptation.展开更多
Background:Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation.However,without sufficient ankle kinetics and muscle activity ...Background:Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation.However,without sufficient ankle kinetics and muscle activity information in the literature,the detailed mechanism of ankle sprain is still unrevealed.The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability(CAI)and compare to their normal trials with data of kinematics,kinetics,and electromyography(EMG).Case description:Two young female participants accidentally experienced the ankle giving way when landing on a 25°lateral-tilted force plate.3 D kinematics,kinetics,and muscle activity were recorded for the lower extremity.Qualitative comparisons were made between the giving way trials and normal trials for joint angles,angular velocities,moments,centers of pressure and EMG linear envelopes.Results:One participant’s giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials.Another participant’s giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials.Conclusion:A vulnerable ankle position(i.e.,more inverted and internally rotated),and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains.A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.展开更多
IT is so tempting for those privileged with education or wealth to suspect that those who are less fortunate lack more than just money, to suspect they are deficient in motivation, ability, or even intelligence! But a...IT is so tempting for those privileged with education or wealth to suspect that those who are less fortunate lack more than just money, to suspect they are deficient in motivation, ability, or even intelligence! But a humble peasant woman from Anxi, Fujian, has proven that they lack only opportunity. Afforded the slightest chance, China’s peasants demonstrate clearly why they are indeed her most valuable resource. No sooner had we arrived in China in 1988 than we were up to our ears studying Chinese while raising our展开更多
When my family and I came to Xiamen in southeast China for the first time in 1988,I quickly fell in love with China and became a foreign teacher at Xiamen University.At that time,the living conditions were harsh.Every...When my family and I came to Xiamen in southeast China for the first time in 1988,I quickly fell in love with China and became a foreign teacher at Xiamen University.At that time,the living conditions were harsh.Every day,the running water was out once or more,power outages were frequent,and transportation wasn't convenient But the people were warm,friendly and hospitable.展开更多
TODAY,I’d like to share some ideas about important life lessons we can learn from China’s response to the coronavirus outbreak,along with some encouraging insights from foreigners who lived in China over a century a...TODAY,I’d like to share some ideas about important life lessons we can learn from China’s response to the coronavirus outbreak,along with some encouraging insights from foreigners who lived in China over a century ago.If you understand the spirit of ancient Chinese,and why foreigners had such great respect for both China’s government and its people in the past,you will understand why Chinese today are able to tackle such formidable foes as poverty,hunger,and now the raging epidemic.展开更多
Background:The Identification of Functional Ankle Instability(IdFAI)is a valid and reliable tool to identify chronic ankle instability;however,it was developed in English,thus limiting its usage only to those who can ...Background:The Identification of Functional Ankle Instability(IdFAI)is a valid and reliable tool to identify chronic ankle instability;however,it was developed in English,thus limiting its usage only to those who can read and write in English.The objectives of our study were to(1)cross-culturally adapt a Chinese(Mandarin)version of the IdFAI and(2)determine the psychometric properties of the Chinese version IdFAI.Methods:The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages:(1)initial translation,(2)synthesis of the translations,(3)back translation,(4)developing the pre-final version for field testing,(5)testing the pre-final version,and(6)finalizing the Chinese version of IdFAI(IdFAI-C).Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups:bilingual(n=20)and Chinese(n=625).Results:A high degree of agreement was found between the English version of IdFAI and IdFAI-C(intra-class correlation_(2,1)=0.995).An excellent internal consistency(Cronbach'sα=0.89),test—retest reliability(intra-class correlation_(2,1)=0.970),and construct validity(r(625)=0.67)was also found for the IdFAI-C.In addition,the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI.Conclusion:The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability.Therefore,we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.展开更多
基金supported by NIH R01 AR052461 and NIH R01 AR069148supported by a NSF Graduate Research Fellowship. A. E. M.supported by training grant T32 AR059038
文摘The vast osteocytic network is believed to orchestrate bone metabolic activity in response to mechanical stimuli through production of sclerostin, RANKL, and osteoprotegerin(OPG). However, the mechanisms of osteocyte mechanotransduction remain poorly understood. We've previously shown that osteocyte mechanosensitivity is encoded through unique intracellular calcium (Ca^(2+) ) dynamics. Here, by simultaneously monitoring Ca^(2+) and actin dynamics in single cells exposed to fluid shear flow, we detected actin network contractions immediately upon onset of flow-induced Ca^(2+) transients, which were facilitated by smooth muscle myosin and further confirmed in native osteocytes ex vivo. Actomyosin contractions have been linked to the secretion of extracellular vesicles(EVs), and our studies demonstrate that mechanical stimulation upregulates EV production in osteocytes through immunostaining for the secretory vesicle marker Lysosomal-associated membrane protein 1(LAMP1) and quantifying EV release in conditioned medium, both of which are blunted when Ca^(2+) signaling was inhibited by neomycin. Axial tibia compression was used to induce anabolic bone formation responses in mice, revealing upregulated LAMP1 and expected downregulation of sclerostin in vivo. This load-related increase in LAMP1 expression was inhibited in neomycin-injected mice compared to vehicle.Micro-computed tomography revealed significant load-related increases in both trabecular bone volume fraction and cortical thickness after two weeks of loading, which were blunted by neomycin treatment. In summary, we found mechanical stimulation of osteocytes activates Ca^(2+) -dependent contractions and enhances the production and release of EVs containing bone regulatory proteins. Further, blocking Ca^(2+) signaling significantly attenuates adaptation to mechanical loading in vivo, suggesting a critical role for Ca^(2+) -mediated signaling in bone adaptation.
文摘Background:Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation.However,without sufficient ankle kinetics and muscle activity information in the literature,the detailed mechanism of ankle sprain is still unrevealed.The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability(CAI)and compare to their normal trials with data of kinematics,kinetics,and electromyography(EMG).Case description:Two young female participants accidentally experienced the ankle giving way when landing on a 25°lateral-tilted force plate.3 D kinematics,kinetics,and muscle activity were recorded for the lower extremity.Qualitative comparisons were made between the giving way trials and normal trials for joint angles,angular velocities,moments,centers of pressure and EMG linear envelopes.Results:One participant’s giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials.Another participant’s giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials.Conclusion:A vulnerable ankle position(i.e.,more inverted and internally rotated),and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains.A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.
文摘IT is so tempting for those privileged with education or wealth to suspect that those who are less fortunate lack more than just money, to suspect they are deficient in motivation, ability, or even intelligence! But a humble peasant woman from Anxi, Fujian, has proven that they lack only opportunity. Afforded the slightest chance, China’s peasants demonstrate clearly why they are indeed her most valuable resource. No sooner had we arrived in China in 1988 than we were up to our ears studying Chinese while raising our
文摘When my family and I came to Xiamen in southeast China for the first time in 1988,I quickly fell in love with China and became a foreign teacher at Xiamen University.At that time,the living conditions were harsh.Every day,the running water was out once or more,power outages were frequent,and transportation wasn't convenient But the people were warm,friendly and hospitable.
文摘TODAY,I’d like to share some ideas about important life lessons we can learn from China’s response to the coronavirus outbreak,along with some encouraging insights from foreigners who lived in China over a century ago.If you understand the spirit of ancient Chinese,and why foreigners had such great respect for both China’s government and its people in the past,you will understand why Chinese today are able to tackle such formidable foes as poverty,hunger,and now the raging epidemic.
文摘Background:The Identification of Functional Ankle Instability(IdFAI)is a valid and reliable tool to identify chronic ankle instability;however,it was developed in English,thus limiting its usage only to those who can read and write in English.The objectives of our study were to(1)cross-culturally adapt a Chinese(Mandarin)version of the IdFAI and(2)determine the psychometric properties of the Chinese version IdFAI.Methods:The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages:(1)initial translation,(2)synthesis of the translations,(3)back translation,(4)developing the pre-final version for field testing,(5)testing the pre-final version,and(6)finalizing the Chinese version of IdFAI(IdFAI-C).Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups:bilingual(n=20)and Chinese(n=625).Results:A high degree of agreement was found between the English version of IdFAI and IdFAI-C(intra-class correlation_(2,1)=0.995).An excellent internal consistency(Cronbach'sα=0.89),test—retest reliability(intra-class correlation_(2,1)=0.970),and construct validity(r(625)=0.67)was also found for the IdFAI-C.In addition,the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI.Conclusion:The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability.Therefore,we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.
