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Atherosclerotic plaque rupture is the main cause of many cardiovascular diseases, and biomechanical factors play an important role in the process of plaque rupture. In the study of plaque biomechanics, there are relatively few studies based on fatigue fracture failure theory, and most of them mainly focus on the whole fatigue propagation process from crack initiation to plaque rupture, while there are few studies on the influence of crack on plaque rupture at a certain time in the process of fatigue propagation. In this paper, a two-dimensional plaque model with crack was established. Based on the theory of fracture mechanics and combined with the finite element numerical simulation method, the stress intensity factor (SIF) and related influencing factors at the crack tip in the plaque were studied. The SIF was used to measure the influence of crack on plaque rupture. The results show that the existence of crack can lead to local stress concentration, which increases the risk of plaque rupture. The SIF at the crack tip in the plaque was positively correlated with blood pressure, but negatively correlated with fibrous cap thickness and lipid pool stiffness. The effect of the thickness and angle of lipid pool on the SIF at the crack tip in the plaque was less than 4%, which could be ignored. This study provides a theoretical basis for the risk assessment of plaque rupture with cracks.
Assuntos
Humanos , Fenômenos Biomecânicos , Simulação por Computador , Placa Aterosclerótica , Estresse MecânicoRESUMO
Objective To compare the therapeutic effects of laparoscopic and open surgery treatment for choledocholithiasis.Methods Forty-six cases with choledocholithiasis were randomly divided into laparoscopic surgery group(n = 21)and open surgery group(n = 25).Comparison was conducted between the two groups in terms of operative time,hospitalization day,anorechlnl exhaust time,cases of postoperative pain,the amount of intraoperative bleeding and postoperative complications.Results Hospitalization day(10.5 ±2.4d),anorechlnl exhaust time(27.2 ±9.4h),cases of postoperative pain(28.6%)in the laparoscopic surgery group were significantly better than those in open surgery group(14.3 ±2.5d,54.6 ±12.5h,88.0%)(P ＜0.05).The operative time and the amount of intraoperative bleeding was not significantly different between two groups(P ＞ 0.05).The rate of infection of incisional wound in the laparoscopic surgery group(0%)was lower than that of open surgery group 24.0%(P ＜ 0.05).No residual calculi and bile leakage were found in both groups.The other postoperative complications were not significantly different between the two groups(P ＞ 0.05).Conclusion Laparoscopic choledocholithotomy is safe,effective and feasible.Compare with open surgery,it is a less invasive proceduce for the treatment of choledocholithiasis with the virtue of little trauma,fast recovery,short hospitalization days and few complication.
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Objective To explore the expression of c-fos gene at early stage and changes of focal cerebral blood flow (CBF) in brain tissue after intracerebral hemorrhage(ICH) in rats.Methods The rat models with ICH were made by Nath improvement method;fos protein in brain tissue and the expression of c-fos mRNA were measured by immunohistochemistry and RT-PCR method;its focal cerebral blood flow (CBF) was measured by hydrogen clearing method.Results The expression of fos protein was found at 1 h after ICH in the ipsilateral basal ganglia after ICH,it peaked at 3 h;c-fos mRNA peaked at 1 h after ICH,and had still expression of higher level after 3 h;cBF was reduced at 1 h after ICH,and returned to the level of the control group by 3 h and maintained to 24 h after ICH,and then appeared the reduction of CBF during 24 h again.Conclusion The increase and long induction expression of c-fos gene were showed in brain tissue of hematoma periperal zone and contralateral cortex one.Although focal CBF reduced after ICH in rats,it wasn't consistent with the expression of c-fos gene.
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Objective:To study the effect of electromyographic feedback therapy on hemiplegia of patients with cerebral infarction Method: 120 hemiplegic patients were randomly divided into study group (n=60) and control group (n=60) The former received electromyographic feedback trainings, 6 times a week for four weeks, in addition to regular medication All patients were evaluated with Fugl-Meyer Assesment and Barthel Index Results: The improvement of study group was greater evaluated by both methods Discussion:The eletromyographic feedback can improve motor function of hemiplegic patients and do benefit their activities of daily living