Cardioprotective effects of resveratrol following myocardial ischemia and reperfusion

Resveratrol (RSV), a plant origin polyphenol, has shown beneficial cardiovascular effects. In this study, isolated hearts from male Wistar rats were studied using the Langendorff technique. Following 30 min stabilization, the hearts underwent 30 min global ischemia and 120 min reperfusion. The perfusion solution in the test group contained RSV (10 μM). Hemodynamics of the hearts, the markers of myocardial damage including creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), and troponin I were studied during the study. Furthermore, the infarct size and the markers of oxidative stress including catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GPX) were assayed in the homogenates of the hearts. The release of nitrite from the hearts and the occurrence of ventricular arrhythmias were also monitored throughout the experiment. Resveratrol caused a significant improvement in the restoration of the mechanical performance of the hearts following myocardial ischemia and reperfusion (MIR). Besides, the infarct size, CK-MB, LDH, and troponin I declined in the test group. Besides, the cardiac release of nitrite increased, and the redox status of the heart was improved as indicated by the levels of CAT, SOD, GPX, and MDA. Finally, the treatment caused significant decreases in the occurrences of single and salvo arrhythmias, ventricular tachycardia, and ventricular fibrillation. The current study suggests strong cardioprotective and antiarrhythmic effects for RSV following MIR.

     

Non-invasive in vivo measurement of the shear modulus of human vocal fold tissue

Voice is the essential part of singing and speech communication. Voice disorders significantly affect the quality of life. The viscoelastic mechanical properties of the vocal fold mucosa determine the characteristics of the vocal folds oscillations, and thereby voice quality. In the present study, a non-invasive method was developed to determine the shear modulus of human vocal fold tissue in vivo via measurements of the mucosal wave propagation speed during phonation. Images of four human subjects' vocal folds were captured using high speed digital imaging (HSDI) and magnetic resonance imaging (MRI) for different phonation pitches, specifically fundamental frequencies between 110 and 440 Hz. The MRI images were used to obtain the morphometric dimensions of each subject's vocal folds in order to determine the pixel size in the high-speed images. The mucosal wave propagation speed was determined for each subject and at each pitch value using an automated image processing algorithm. The transverse shear modulus of the vocal fold mucosa was then calculated from a surface (Rayleigh) wave propagation dispersion equation using the measured wave speeds. It was found that the mucosal wave propagation speed and therefore the shear modulus of the vocal fold tissue were generally greater at higher pitches. The results were in good agreement with those from other studies obtained via in vitro measurements, thereby supporting the validity of the proposed measurement method. This method offers the potential for in vivo clinical assessments of vocal folds viscoelasticity from HSDI.