Numerical study of biomechanical characteristics of plaque rupture at stenosed carotid bifurcation:a stenosis mechanical property-specific guide for blood pressure control in daily activities

Acute stress concentration plays an important role in plaque rupture and may cause stroke or myocardial infarction.Quantitative evaluation of the relation between in vivo plaque stress and variations in blood pressure and flow rates is valuable to optimize daily monitoring of the cardiovascular system for high-risk patients as well as to set a safe physical exercise intensity for better quality of life.In this study,we constructed an in vivo stress model for a human carotid bifurcation with atherosclerotic plaque,and analyzed the effects of blood pressure,flow rates,plaque stiffness,and stenosis on the elastic stress and fluid viscous stress around the plaque.According to the maximum values of the mechanical stress,we define a risk index to predict the risk level of plaque rupture under different exercise intensities.For a carotid bifurcation where the blood flow divides,the results suggest that the stenosis ratio determines the ratio of the contributions of elastic shear stress and viscous shear stress to plaque rupture.A n increase of the plaque stiffness enhances the maximum elastic shear stress in the plaque,indicating that a high-stiffness plaque is more prone to rupture for given stenosis ratio.High stress co-localization at the shoulder of plaques agrees with the region of plaque injury in clinical observations.It is demonstrated that,due to the stress-shield effect,the rupture risk of a high-stiffness plaque tends to decrease under high-stenosis conditions,suggesting the existence of a specific stenosis corresponding to the maximum risk.This study may help to complement risk stratification of vulnerable plaques in clinical practice and provides a stenosis mechanical property-specific guide for blood pressure control in cardiovascular health management.

HPLC analysis of 16 compounds from Artemisia ordosica

Objective: To establish a high-performance liquid chromatographic method(HPLC) for the simultaneous determination of 16 compounds from Artemisia ordosica.Methods: HPLC was used to analyze 16 quality indicators of A. ordosica. The HPLC conditions were as follows: Agilent Eclipse Plus C18column(250 mm × 4.6 mm, 5 μm) with acetonitrile(A)-water(B) as mobile phase, gradient elution: 0–10 min, 75%-65% B;10–30 min, 65%-35% B;and finally 30–40 min, 35%-15%B. The flow rate was 1.0 mL/min, the column temperature was 40 °C, the injection volume was 10 μL, and monitored by absorbance at 285 nm for compounds 1–10, 12 and 225 nm for compounds 11, 13–16.Results: Under the selected experimental chromatographic conditions, compounds 1–16 showed good linearity(r > 0.9993) in a wide concentration range. Their average recoveries were 99.50%, 95.38%,97.75%, 96.00%, 98.20%, 97.50%, 95.50%, 99.33%, 96.75%, 96.50%, 98.50%, 97.83%, 99.20%, 95.33%, 97.33%and 96.30%, respectively, and the RSD were 1.99%, 1.81%, 1.63%, 1.98%, 1.67%, 1.92%, 1.74%, 1.67%,1.90%, 1.72%, 1.88%, 1.83%, 1.79%, 1.76%, 1.81% and 1.96%, respectively.Conclusion: Based on the results of the HPLC analysis, it was concluded that p-hydroxycinnamic acid(1),O-hydroxycinnamic acid(2), coniferyl alcohol(5), 5,4’-dihydroxy-7,3’-dimethoxyflavanone(8), 5,4’-dihy droxy-7-methoxyflavanone(9), 5-hydroxy-7,4’-dimethoxyflavanone(12), dehydrofalcarindiol(13), arteordoyn A(14), dehydrofalcarinol(15) and capillarin(16) are best suited for the role of quality indicators of A. ordosica grown in different ecological environments.