Objective To study ischemic effects on reentrant activities and cardiac arrhythmias using a computational approach. Method The Noble 98 mathematical model of ventricular cell was used in the study. The operator splitting and adaptive time step methods were utilized to integrate the partial differential equations in cardiac conduction models. The ischemic cells were simulated by decreasing the intracellular ATP concentration, reducing the Na+ conductance, and increasing the extracellular K+ concentration in a two-dimensional tissue. Spiral waves were initiated by the cross field technique. Result The results showed that spiral waves in local severe ischemia displayed three different morphologies,whereas in moderate ischemia only two kinds of wave forms exhibited. When the degree of ischemia reached a critical value, the reentrant wave could break. But for larger areas of ischemia spiral wave formed a typical functional reentry around the obstacle. Conclusion The study demonstrates that size and level of ischemia have effects on VTs and VFs. Large ischemic area is beneficial for maintenance of spiral wave and can provide a high probability in the genesis of VTs. Spiral waves can easily break up and degenerate into VFs under critical area or level of ischemia.

To investigate the expressions and changes of serum soluble intercellular adhesion molecule-1 (sICAM-1) in lung cancer patients before and after operation and the roles of sICAM-1 in differential diagnosis, metastatic potential, and prognosis. Methods From 2002 to 2003, a total of 17 samples of lung carcinoma tissues and sera were studied. The other 11 non-cancer patients were employed as the controls. Cell surface sICAM-1 levels were analyzed by immunohistochemistry method and ELISA. Results The serum sICAM-1 concentration in the cancer patients was (432.0?124.4) ng/ml. In the controls, however, the serum concentration of sICAM-1 was (262.3?77.7) ng/ml. In patients with lung cancer, the serum concentration of sICAM-1 was significantly higher than that of the controls (P0.05). Conclusion The serum sICAM-1 concentrations in lung cancer patients may play an important role in staging and may also serve as a useful indicator of advanced disease.

Objective To discuss the safety and effectiveness of robot-assisted thyroidectomy using Da Vinci system.Methods Endoscopic thyroidectomy assisted by Da Vinci system was performed in 20 patients,including 5 cases of thyroidadenoma,4 cases of nodular goiter,and 11 cases of thyroid carcinoma.The max diameter of thyroid lump is 5.33 cm.Among 9 cases of benign thyroid neoplasm,5 cases underwent unilateral subtotal lobectomy,and 4 cases underwent unilateral near total thyroidectomy.Among 11 cases of thyroid carcinoma,7 cases underwent bilateral near total thyroidectomy,and 4 cases underwent bilateral total thyroidectomy,at the same time,all the 11 cases underwent central region lymph node dissection.Results The robot-assisted endoscopic thymidectomy was successfully carried out in 20 cases.The mean operation time was 206.4 (105～372)min.The mean operative blood loss was 27.3 ml.The draining tube was moved 3 to 6 days after surgery.The mean postoperative hospital stay was 4.9 days.The mean hospital expense was 60 172 yuan RMB.No complication occurred.20 patients were satisfied with the cosmetic effect and compararive curative effect.Conclusions The robot-assisted endoscopic thymidectomy is an efective method for thyroid diseases.The methed can get more clear vision,higher safety,and good cosmetic efect.

Computer simulation is one of the powerful protocols to study electrophysiology theoretically. In this paper,the algorithm of Rush and Larsen was used to solve the ordinary differential equations (ODE's) in the Luo-Rudy models of mammalian ventricular cell. The operator splitting and adaptive time step methods were used to solve the partial differential equations (PDE's) in cardiac tissue conduction models. Using these methods we accomplished the simulation programs of single ventricular cell model and two-dimensional (2-D) tissue model. The methods of initiating spiral waves were studied with this software. The data obtained from 2-D simulation can be used for further study on isopotential contour lines, spiral wave tip trajectories, and pseudo-ECG.
Algorithms ; Computer Simulation ; Electrocardiography ; Electrophysiology ; Heart Ventricles ; cytology ; Humans ; Models, Cardiovascular ; Myocytes, Cardiac ; physiology ; Software ; Ventricular Function

Ventricular fibrillation (VF) is the main cause of sudden death in cardiovascular diseases. The effects of electrophysiological heterogeneity and dynamic factors bring a lot of difficulties in understanding and revealing the mechanisms of VF. Cardiac short-term memory is one of the factors that make invalidation of restitution curve slope as the criteria for transition from ventricular tachycardia to VF. Therefore, investigation of inherent properties of short-term memory and its role in VF has great significance. In this paper we took advantage of the perturbed down-sweep protocol to measure dynamic and local S1S2 restitution curves on three widely used mathematical models to reveal their memory property. And by making abrupt change of the stimulation cycle length, we examined the attenuation process of the memory. The results showed, the rate-dependent action potendial duration (APD) is related with S1 pacing. The APD difference under different S2 cycle length is more pronounced with short S1 cycle length. Except the Luo-Rudy 1991 model, the Luo-Rudy 1994 and Noble 1991 models can at least reflect some of the short-term memory. And the memory attenuated in exponential way. Therefore, in quantitative electrophysiological study, these two models can be used in the future for investigating the characteristics of the short-term memory and its contribution to VF.
Action Potentials ; Computer Simulation ; Electrocardiography ; Heart Conduction System ; physiopathology ; Humans ; Models, Cardiovascular ; Models, Theoretical ; Myocardial Contraction ; physiology ; Ventricular Fibrillation ; physiopathology ; Ventricular Function

Cardiac reentry is one of the important factors to induce arrhythmias. It could lead to ventricular tachycardia (VT) or even fibrillation (VF), resulting in sudden cardiac death. With the wide use of computer in the quantitative study of electrophysiology, the three-dimensional virtual heart for simulations needs to be developed imminently in computer. In this paper, numerical algorithm of the model was studied. The three-dimensional model was constructed by integrating Luo-Rudy 1991 ventricular cell model and diffusion equation. The operator splitting method was employed to solve the model. The alternate direction iterative (ADI) format and seven-point centered difference method were used for the partial differential equation. And the discrete format with second-order accuracy was taken for the boundary conditions. The results showed that the ADI format and seven-point centered difference method both could successfully figure out the membrane potential and electrical activities with good numerical stability. However, computing consumption could be greatly reduced with the ADI format, implying that the ADI method with large time step was more powerful in numerical simulations.
Action Potentials ; Algorithms ; Heart ; physiology ; Heart Ventricles ; Humans ; Imaging, Three-Dimensional ; Models, Cardiovascular ; Myocardium

Malignant arrhythmias and ventricular fibrillation are generally accepted as one of the major causes of death in cardiovascular diseases. Based on the H-H equations, the mathematical model of the cardiac cell action potential consists of the ion channels, pumps, exchangers and transporters that are closely connected with intra- and extra-cellular ion concentrations, the channel's conditions, nerve transductors and drugs. It can build the link between cell electrophysiology and clinical pathophysiology. By altering the cellular environments the computer simulating study on this kind of model can help us look into the electrophysiological changes of the cardiac tissue and even the whole heart and investigate the mechanisms of the cardiac arrhythmias as well. The components of the model and its computer simulating study are introduced in the paper.
Action Potentials ; Arrhythmias, Cardiac ; physiopathology ; Computer Simulation ; Heart ; physiopathology ; Humans ; Models, Cardiovascular ; Ventricular Fibrillation ; physiopathology

OBJECTIVETo investigate the clinical significance of phosphorylated caspase-8 by Src in patients with operable non-small cell lung cancer.

METHODSSrc and caspase-8 expressions were tested using immunohistochemistry in non-small cell lung cancer tissues and control lung tissues. The expression of phosphorylated caspase-8 at 380 tyrosine by Src was detected using Western blotting. The disease-free survival (DFS) of patients positive and negative for phosphorylated caspase-8 was analyzed with Kaplan-Meire survival curve.

RESULTSNo significant difference was found in the positivity rate of caspase-8 or Src between the cancer tissues and control lung tissues (76.3% vs 83.3%, P>0.05; 70.1% vs 66.4%, P>0.05). All the patients with Casp8- and Src-positive cancers were positive for phosphoryalted caspase-8, whose expression rate was significantly higher in the cancer tissues than in the paired control lung tissues (52.4% vs 7.1%, P<0.05). The 2-year DFS was significantly higher in patients negative for phosphorylated caspase-8 than in the positive patients (32.0% vs 60.3%, P<0.05).

CONCLUSIONPhosphorylated caspase-8 may serve as a predictor for a poorer DFS in patients with operable non-small cell lung cancer.

Blotting, Western ; Carcinoma, Non-Small-Cell Lung ; metabolism ; Caspase 8 ; metabolism ; Disease-Free Survival ; Humans ; Immunohistochemistry ; Lung Neoplasms ; metabolism ; Phosphorylation

Objective To investigate the effect of time interval between diagnosis and surgical treatment on the prognosis of breast cancer.Methods A retrospective study that include a total of 252 female patients who underwent breast cancer diagnosis and treatment in the Second Affiliated Hospital of Xi'an Jiaotong University from April 2012 to August 2014 were included in the present study,the average age was (58.2 ± 10.8) years old,range from 31 to 67 years old.General demographic information and data of tumor were collected.Information on postoperative recurrence,metastasis,death,and disease-free survival status of breast cancer patients were followed up 5 years by outpatient follow-up or telephone follow-up.All participants were divided into four groups (＜2 weeks,2-4 weeks,4-8 weeks,≥8 weeks) by the time interval between diagnosis and surgical treatment,including 26,118,78 and 30 cases,respectively.In addition,according to the diameter of breast cancer tumors,all participants were divided into three groups (＜20 mm,20-40 mm,and ≥40 mm),including 99,124,and 29 cases,respectively.According to the results of pathological examination of the lymph nodes obtained during intraoperative dissection,the all participants were divided into three groups (lymph nodes without metastasis,1 to 3 metastasis,and ≥3 metastasis),including 66,124,and 62 cases,respectively.The Cox proportional regression risk models were used to assess the hazard ratio (HR) and its 95％ confidence interval (CI) of time interval between diagnosis and surgical treatment with the prognosis of breast cancer,with adjustment for age,education levels and body mass index.Further,stratified analysis by tumor characteristics,including pathological type,histological grade,tumor diameter,lymph node metastasis,and receptor expression were also conducted to evaluated the above association.Kaplan-Meier survival curve was used to evaluate the effects of time interval between diagnosis and surgical treatment on the prognosis of breast cancer.Results The Kaplan-Meier survival curves for the five-year follow-up of total survival time between 4 different time intervals groups showed significantly different (P ＜0.001),and patients with a pre-treatment interval of ＜2 weeks had the longest survival time,while those with ≥8 weeks had the lowest survival time.With a one-week interval before treatment,the overall risk of death in breast cancer patients increased by 6％ (HR =1.06,95％ CI:1.01-1.1 l),and the risk of breast cancer death increased by 8％ (HR =1.08,95％ CI:1.02-1.14),the risk of distant metastasis of breast cancer cells increased by 10％ (HR =1.10,95％ CI:1.08-1.13).With the increase in breast cancer tumor diameter (＜20 mm,20-40 mm,≥40 mm),the overall risk of death due to prolonged treatment interval increased gradually,with HR (95％CI) were 1.06 (1.03-1.09),1.08 (1.02-1.12) and 1.11 (1.05-1.17),respectively.With the increase of lymph node metastasis in breast cancer (no metastasis,metastasis at 1-3,≥ 3 metastasis),the total mortality risk caused by prolonged treatment time interval also showed an increasing trend,with HR (95％CI) were 1.04 (1.02-1.08),1.06 (1.04-1.08) and 1.08 (0.99-1.11),respectively.The same results were also shown in the effect of tumor diameter or distant lymph node metastasis on the association between treatment time interval and breast cancer survival and distant metastasis of breast cancer cells.Conclusion With the prolongation of the time interval between the diagnosis of the breast cancer and the surgical treatment of breast cancer patients,the risk of postoperative death is significantly increased,and the association is more pronounced in breast cancer patients with larger tumor volume or higher distant lymph node metastasis.

Torsades de Pointes is a kind of severe ventricular arrhythmia. Myocardial ischaemia is one of the major causes leading to TdP. In this paper the mechanisms of the TdP were quantitatively studied under the condition of ischaemia based on the Noble98 dynamic model of the ventricular action potential. The study was conducted on one-dimensional homogeneous myocardium with the method of computer simulation. The models were firstly developed to simulate the lower excitability, extracellular accumulation of the K+ concentration or the decreased gap junctions in ischaemic myocardium. By separately reducing the Na+ conductance, increasing the extracellular K+ concentration or decreasing the conductance of the gap junctions enabled us to study the effect of each change in isolation. Then different degrees of ischaemic models were established to study their physiological features. The study showed that the conduction velocity became slower with the ischaemia aggravation, the action potential duration became shorter and the width of the vulnerable window obviously became larger than the normal conditions. The results illustrated that ischaemia was easily leading to unidirectional conduction block and resulted in re-entry and arrhythmias.
Computer Simulation ; Models, Cardiovascular ; Myocardial Ischemia ; physiopathology