Echocardiographic evaluation of pressure overload-induced cardiac remodeling in mice using different ultrasound machines / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the results of echocardiographic evaluation of pressure overload-induced cardiac remodeling in mice using different ultrasound machines.</p><p><b>METHODS</b>Eighteen C57 BL/6 mice were randomly divided into the sham-operated and the transverse aortic constriction (TAC) groups (n=9). Eight weeks after the operation, the cardiac function of TAC group was evaluated using Siemens ultrasonic instrument with 15L8 probe and the differences between the awake and anesthetized states were compared. The heart rate, left ventricular (LV) dimensions, systolic and diastolic functions were measured in both sham-operated and TAC groups using the Siemens ultrasonic instrument and a high-resolution ultrasonic imaging system for small animals (Vevo 770).</p><p><b>RESULTS</b>Compared with the mice in wakefulness, the anesthetized mice showed significantly decreased heart rate and LV fractional shortening (P<0.001) and markedly increased LV end diastolic diameter and LV end systolic diameter (P<0.05). Both machines sensitively detected the cardiac remodeling of TAC mice in comparison with the sham-operated group. Compared with Siemens machine, Vevo 770 provided a higher resolution of 2D and M mode echocardiography with clearer Doppler frequency image of the mitral valve flow for evaluation of the LV diastolic function.</p><p><b>CONCLUSION</b>Both machines are suitable for evaluating cardiac remodeling induced by pressure overload independent of anesthesia, though anesthesia depresses cardiac function. Vevo 770 is optimal to evaluate LV diastolic function in mice.</p>

Molecular imaging of thrombus with microbubbles targeted to alphavbeta3-integrin using an agarose flow chamber model / 南方医科大学学报

<p><b>OBJECTIVE</b>To assess the binding ability of microbubbles targeted to alphavbeta3-integrin (MBp) for thrombus-targeted contrast-enhanced ultrasound.</p><p><b>METHODS</b>Targeted microbubbles were prepared by conjugating the monoclonal antibody against alphavbeta3-integrin to lipid shell of the microbubble via the avidin-biotin bridges. Equivalent isotype control microbubbles (MB) or targeted ultrasound microbubbles (MBp) were randomly added into the flow chamber. After a 30-min incubation with the thrombus fixed in an agarose flow chamber model, the thrombus was washed with a continuous flow of PBS solution (15 cm/s) for 2, 4, 6, 8 and 10 min, followed by thrombus imaging using contrast-enhanced ultrasound and measurement of the video intensity (VI) values of the images.</p><p><b>RESULTS</b>The VI of the thrombus in MBp group was reduced by 28%-66%, while that in control MB group was decreased by 87%-94%, and the VI values of the thrombus group were significantly greater in former group at each of the time points (P<0.05).</p><p><b>CONCLUSION</b>MBP has good targeting ability to the thrombus with resistance to the shear stress after adhesion to the thrombus. In vitro evaluation of the thrombus-binding capability of the targeted microbubble (MBp) by simulating the shear stress in vivo can be helpful for predicting the in vivo effects of ultrasonic molecular imaging using MBp.</p>

Effect of polyethylene oxide on red blood cell velocity in rat cremaster microcirculation / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the drag-reducing effect of polyethylene oxide (PEO) on the velocity of red blood cells in rat cremaster microcirculation.</p><p><b>METHODS</b>Blood samples were collected from 6 Wistar male rats (100-110 g) via the post-orbital venous plexus. The red blood cells were separated by centrifugation and labeled by fluorescinisothiocyate (FITC). After successful establishment of cremaster model, the labeled red blood cells were injected into the jugular vein, and the microcirculation was observed and recorded under fluorescence microscope. The hemodynamic parameters and microcirculation video was recorded every 4 min since 4 min before PEO or normal saline injection. Both PEO (10 ppm) and normal saline was injected into the same rat in random sequence at a constant rate of 3.5 ml/h for 20 min followed by observation for another 20 min. The velocity of the labeled-red blood cells was determined by IPP 6.0 software.</p><p><b>RESULTS</b>Compared with normal saline, PEO significantly increased the velocity of the red blood cells in the rat cremaster microcirculation (498.7-/+182.89 microm/s vs 773.54-/+308.27 microm/s, P=0.012). No significant changes in the heart rate and arterial blood pressure were observed during the experiment (P=0.836, P=0.420).</p><p><b>CONCLUSION</b>PEO at an extremely low concentration can significantly increase the velocity of the red blood cells in rat cremaster microcirculation and produces no significant impact on heart rate and arterial blood pressure.</p>