Ms 250 transducer

PLGA MBs were observed by scanning electron microscope (SEM, JSM-7001F, Japan). To evaluate the release profile, 3 mg of VEGF-loaded or BSA-loaded 75/25 and 50/50 microbubbles (n = 3) were suspended in 2.0 ml of 0.1 M phosphate buffer (pH 7.4), containing 0.1% BSA and microbiologically preserved with sodium azide. The samples were maintained in rotating vials at 37°C. At 2 and 7 days, sample tubes were exposed to ultrasound radiation. The parameters of US exposure were as follows: frequency, 1 MHz; intensity, 2 W/cm²; duty cycle, 50%; pulse recurrent frequency, 100 Hz; and duration, 5 min. At scheduled time intervals, sample tubes were centrifuged (25,000 × g, 15 min) and the supernatants of 100 μl were harvested and frozen at −80°C. The amounts of released VEGF were quantified using ELISA kits, and released BSA was quantified using a BCA Protein Assay Kit. The in vitro ultrasound imaging of MBs was conducted using Visual Sonic 2100 with a MS-250 transducer (VisualSonics, Canada). Blank MBs and VEGF-MBs were dispersed in PBS at 1 × 10⁶/ml, and PBS was used as a control.

Noninvasive trans-thoracic echocardiograms were recorded using a Vevo-2100 High-Resolution Imaging system with a nonlinear MS250 Transducer (13–24 MHz, VisualSonics, Toronto, Canada). Rats were induced with 3–4% isoflurane and maintained with 1.5% isoflurane. Serial echocardiography was performed at 0/4/8/10/12 weeks after start diet, with analysis blinded to study groups.

Ultrasonic test was performed with a Vevo2100 imaging system and a MS250 transducer, which is designed specifically for mice and rats (Visual Sonics). Rats were anesthetized with 2% isoflurane during the ultrasonic test procedure, the diameter and wall thickness of common carotid artery (CCA) were measured during diastole of left ventricle.

Transthoracic echocardiography was performed, as previously described [9 (link)], under light anaesthesia (1% isoflurane supplemented with 100% O₂), prior to sacrifice. Images were acquired using a high-frequency ultrasound system (Vevo 2100, MS-250 transducer, Visualsonics, Toronto, ON). Two dimensional long-axis images of the LV in parasternal long- and short-axis views with M-mode measurements at mid-papillary muscle level and linear dimensions were analyzed offline (Vevo 2100 software v. 1.8) using the standard leading edge-to-leading edge technique by a single investigator, masked to treatment. Fractional shortening (FS%) was calculated according to the formula: FS% = (LVIDd − LVIDs)/LVIDd × 100, where LVIDd and LVIDs are end-diastolic diameter and end-systolic diameter respectively, as previously described. Three consecutive cardiac cycles were averaged for all analyses.