ABSTRACT
Objective:To investigate the characteristics of early myocardial mechanics changes in diabetic cardiomyopathy (DCM).Method:Sixty healthy 4-week-old male C57BL/6J mice were randomly divided into the T2DM group ( n=30) and the control group ( n=30). The T2DM group was fed with high-fat diet for 4 weeks, and accepted injection of a single high-dose of streptozotocin (STZ) intraperitoneally. Finally, the model was established successfully in 23 mice. The control group was fed with a normal diet and treated with citrate buffer liquid at an equal dose as T2DM group. Then, nine mice were randomly selected from each of the two groups every 4 weeks until the end of the 24th week. Six of the nine mice were randomly selected to perform 7.0 T MR scanning after measuring blood glucose and body weight. Cine images were acquired through cardiovascular MR feature tracking (CMR-FT). The obtained parameters included the left ventricle global peak circumferential strain (LV-GPCS), left ventricle global peak radial strain(GPRS) and the ejection fraction (EF), etc. The rest three mice were sacrificed for observation of the changes of interstitial fibers and micro-vessels in myocardial tissue with Sirius red staining. One-way analysis of variance (ANOVA) and t test were used for comparison. Results:There were significant differences in blood glucose levels between the two groups during the observation period ( P<0.05). In the 4 th-24 th week, the value of GPCS in T2DM group showed a downward trend, and the difference was statistically significant ( F = 8.23, P<0.001). Compared with the control group, the value of GPCS in T2DM group was statistically significant at the 20 th and 24 th week (the 20 th week: -11.4%±2.1% in the T2DM group vs. -14.3%±1.9% in the control group, t=2.54, P=0.029;the 24 th week: -12.3%±1.7% in the T2DM group vs. -14.6%±1.8% in the control group, t=2.35 , P=0.040), while the EF value was different at the 24 th week (51%±5% in the T2DM group vs. 62%±6% in the control group, t=3.38, P=0.007). There was no significant difference in the GPRS of the T2DM mice group over time or compared with the controls ( P>0.05). Moreover, the pathological results showed that the myocardial interstitial fibers in the T2DM group had remarkably increased since the 12 th week. Conclusions:The alterations in myocardial interstitial fibers and myocardial contractility appeared early in T2DM mice. Especially, the left ventricle global peak circumferential strain value is superior to the EF value in reflecting the early changes in DCM.
ABSTRACT
The gene expressions of codeinone reductase (COR) and berberine bridge enzyme (BBE) in Papaver somniferum were blocked by RNA hairpin of RNA interference (RNAi). The complete sequences of COR and BBE genes were cloned by reverse transcription-polymerase chain reaction (RT-PCR), the results of homology comparison revealed that the cloned COR and BBE genes had high homology with the other gene family members reported in the GenBank. The target sequences of COR and BBE genes were screened in accordance with the design principle of RNAi, a 643 bp fusion gene was obtained by the method of overlapping PCR, then plant expression vector ihpRNA was constructed based on intermediate vector pHANNIBAL and plant expression vector pCEPSPS. With that 78 transgenic plants were obtained through Agrobacterium-mediated and 17 positive plants were screened by PCR, that could initially indicate that the target fragments of COR and BBE gene had been integrated into tobacco genome.