RESUMO
Extracellular matrix is the main element to provide mechanical clues for cells. The response of stem cells to mechanical signals is mainly achieved through the cytoskeleton. After mechanical signal is transmitted, cytoskeleton can form contractile microfilaments that actively generate tension through reorganization induced by microenvironment changes. The mechanical signals can regulate gene expression through either coupling with the nuclear skeleton directly or being transformed by the second message. Recent studies have proven that cytoskeleton tension has a series of impact on lineage specification, proliferation, differentiation and apoptosis of bone mesenchymal stem cells (BMSCs). BMSCs are of great significance in bone reconstruction and clinical treatment. The possible mechanisms about mechanotransduction and its effects of cytoskeleton tension on osteogenesis of BMSCs after micro-environmental changes were summarized.
RESUMO
Objective To investigate the relationships between the structure ,function of left atrial as well as cardiac biomarkers and left atrial spontaneous echo contrast ( SEC ) in patients with non‐valvular atrial fibrillation ( NVAF ) ,and evaluate its predictive value for left atrial SEC . Methods T hirty‐four control subjects and 80 patients with NVAF were included ,patients with NVAF were divided into positive group ( 30 cases) and negative group ( 50 cases) according to w hether SEC was presented on transesophageal echocardiography ( T EE ) . Clinical and laboratory data were collected ,including medical history ,cardiac troponin I ( cT nI) ,and pro‐brain natriuretic peptide ( pro‐BNP ) ,etc . T hen CHA2 DS2‐VASc scores were calculated .The left atrial appendage width ( W LAA ) ,left atrial appendage depth ( DLAA ) ,left atrial appendage blood flow velocity ( V LAA ) ,left atrial volume index ( LAVI) and other parameters were measured by T EE and transthoracic echocardiography ( T T E) ,and left atrial ejection fraction ( LAEF ) was calculated . T he clinical and T EE parameters were compared between the positive and negative group ,T T E parameters and cardiac biomarkers levels were compared among the three groups ,and ROC curve was used to evaluate the diagnostic efficiency . Results ①Compared with those in control group ,the value of LAVI and pro‐BNP were significantly increased and LAEF was significantly decreased in negative group ( all P ＜ 0 .01 ) . ②Compared with those in negative group ,CHA 2 DS2‐VASc scores ,WLAA ,DLAA ,LAVI and pro‐BNP levels in positive group showed a significant increase ( all P ＜0 .01) ,LAEF and VLAA showed a significant reduction ( all P ＜0 .01) . ③cT nI between negative group and control group did not show statisticant difference ( P＞0 .05) ,but presented a significant increase in positive group compared with those in control group and negative group (all P ＜0 .01).T he AUC ,sensitivity and specificity of CHA 2 DS2‐VASc scores for SEC were 0 .71 (95% CI :0 .60 ～ 0 .82 ) ,73 .3% and 62 .0%,respectively .When left atrial structural and functional parameters (LAVI and LAEF ) combined with cardiac biomarkers (cT nI and pro‐BNP ) ,the AUC , sensitivity and specificity for SEC were 0 .90 (95% CI :0 .84 ～ 0 .97 ) ,74 .0% and 100%,respectively ,both enhanced w hen compared with CHA 2 DS2‐VASc scores alone ( P ＜ 0 .01 ).Conclusions Left atrial enlargement ,decreased function and elevated levels of cardiac biomarkers are associated with left atrial SEC in patients with NVAF .CHA2 DS2‐VASc scores can be used for perdicting left atrial SEC ,left atrial structural and functional parameters (LAVI and LAEF) combined with cardiac biomarkers (cT nI and pro‐BNP) provide significant increments in prediction of left atrial SEC .