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.

Objective To analyze the clinicopathologic characteristics,treatment and prognosis of retinoblasto-ma without calcification.Methods The clinic and pathologic data of 20 cases of retinoblastoma without calcification were analyzed retrospectively.All the cases were selected from 710 cases of retinoblastoma archived in Beijing Tongren Hospital,Capital Medical University from April 2010 to April 2015.The inclusion criteria was no calcification on CT scan before treatment.The patients after enuclea-tion were diagnosed according to pathology;the patients without enu-cleation were diagnosed according to clinical manifestations,Retcam fundus,ophthalmic ultrasound and the reduction of tumor after chemotherapy.The clinical features,treatment and prognosis were summarized through statistical analysis of the 20 cases.The patients were followed -up through clinical reexamination and telephone calls.Results In this study,there were 14(70.0%)male and 6(30.0%)female patient′s;there were 19 cases(95.0%)less than 5 -year -old,14 cases (70.0%)less than 3 -year -old,1 case (5.0%)less than 1 -year -old.Eighteen cases (90.0%)were unilateral disease,and 2 cases (10.0%)were bilateral disease.According to international Intraocular Retinoblastoma Classification stage:4 cases (18.2%)in stage E ,17 cases (77.3%)in stage D ,1 case (4.5%)in stage C.Five cases (25.0%)were enucleated eyes,and pathology report was retinoblastoma.Nine cases (45.0%) were treated with pre -enucleation chemotherapy,and finally enucleated after poor tumor shrinkage or recurrence,and the pathology was retinoblastoma.Five cases (25.0%)without enucleation were stable.One case (5.0%)failed to follow -up owing to the patients irregular treatment.In 14 enucleation cases,histopathologic high risk factors could be found in 3 cases (21 .4%),and couldn′t be found in the other 11 cases (78.6%).In the cases that were not enuclea-ted,the tumor diminished in size or new calcification presented in the fundus examination,and in 12 cases,new calcifi-cation was pre-sented on follow -up CT scan.Follow -up failed in 1 case(5.0%),but follow -up was available for 19 cases,and among them 13 cases (68.4%)were disease -free survival and 6 cases (31 .6%)were alive with tumor. Conclusions Close attention should be paid to the untypical retinoblastoma with no calcification on CT scan through well -taken medical history and meticulous imaging examination,in order to give early diagnosis and therapy.

Objective To analyze the clinical features,treatment and prognosis of the pancreatoblastoma (PB).Methods A total of 9 patients including 4 boys and 5 girls diagnosed as pancreatoblastoma in Beijing Tongren Hospital Affiliated to Capital Medical University between July 2008 and February 2016 were enrolled.The clinical features,therapy and prognosis were analyzed.Results (1) Clinical manifestations:6 cases had abdominal mass,1 case had jaundice,2 cases had abdominal pain at the time of diagnosis;5 cases were found in caput pancreatis,2 cases were found in corpora pancreatis and 2 cases were found in cauda pancreatis;4 cases had local tumor,3 cases had local invasion,and 2 cases had liver metastasis at diagnosis.(2) Enzymology and tumor marks:elevated alpha-fetoprotein (AFP) was found in 5 cases (48.5-52 971.0 μg/L),elevated neuron-specific enolase(NSE) was found in 5 cases(22.4-53.4 pg/L),elevated carbohydrate antigen 125 (CA-125) was found in 5 cases [(40.3-122.8) × 103 U/ L],elevated carbohydrate antigen 19-9 (CA19-9) was found in 2 cases [(65.4-362.5) × 103 U/ L],elevated lactate dehydrogenase was found in 2 cases(380 ～ 838 U/L) and elevated hemodiastase was found in 2 cases (105.5-122.8 U/L).(3) Treatment and prognosis:in 9 patients,the tumors were resected at first in 6 patients,and 5 of them remitted until now,1 of them relapsed after the comprehensive treatment for 9 months.Two of the patients underwent operation after the chemotherapy,in which 1 case received complete resection but without chemotherapy after the surgery,whom relapsed 1 year later;and the other one was resected partly.But after stopping the comprehensive treatment for 6 months,the disease relapsed.One patient could not receive operate because of huge tumor size,and the chemotherapy failed to control tumor progression;the patient died without operation.Three relapsed children were still in chemotherapy.The median follow-up period was 21 months (8-98 months).Conclusions AFP may be used as monitoring indicator for PB.Complete tumor resection is an important factor affecting the outcome.Adjuvant chemotherapy may reduce recurrence and prolong survival.

Objective To summarize the clinical,pathological and radiological features of retinoblastoma (RB)with central nervous system (CNS)metastasis.Methods Twenty -three patients were confirmed to have RB with CNS metastasis in Beijing Tongren Hospital from December 2005 to December 201 3,and their clinical data were retrospectively analyzed.Results (1 )The incidence of RB with CNS metastasis was 1 .83% (23 /1 260 cases),and the incidence of CNS metastasis was 7.64%(1 1 /1 44 cases)if RB with optic nerve involvement which was confirmed through pathology.At first visit 1 0 cases had a confirmed diagnosis of RB with CNS metastasis,while the other 1 3 cases had a diagnosis of RB in extraocular stages.(2)Eleven patients with RB in extraocular stages had the pathological evi-dence of optic nerve involvement which was pathologically confirmed,6 patients had optic nerve involvement with cho-roid involvement,2 patients had optic nerve involvement with nerve sheath involvement.(3)All the patients whose diagnosis of CNS metastasis had the radiological evidence of CNS metastases,and 1 case had autopsy and pathological evidence for extensive brain metastases.The main radiological feature of CNS metastasis was meninges metastasis.Thir-teen cases had the radiological features of meninges metastasis and 5 cases accompanied with spinal cord meninges me-tastasis.Then,the following radiological feature was that 7 cases had the mass of suprasellar pool.(4)Twelve cases with CNS metastasis showed the cerebrospinal fluid (CSF)RB cells positive,and the positive rate was 52.1 7%(1 2 /23 ca-ses).Conclusions (1 )The occurrence of RB with CNS metastasis is very low,but the risk of CNS metastasis in-creased in the patients with the pathological evidence of the optic nerve involvement.(2)The main site of CNS metasta-ses is meninges,followed by mass formation in the suprasellar pool.The main route for CNS metastases was along the optic nerve and /or nerve sheath directly invading and /or disseminating via the CSF.(3)The positive rate of CSF cy-tology is low,and it can be improved through repeated examination.Enhanced magnetic resonance imaging should be the most effective radiology examination for diagnosis and monitoring CNS metastasis.

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

Optical mapping of the membrane potential with voltage-sensitive dyes is an advanced approach that involves in many theories such as molecular photonica, physiology and computer science. Compared with the conventional techniques of membrane patch-clamp and microelectrode, the optical mapping system can measure not only the changes of a single membrane potential from multiple sites simultaneously but also the conduction properties of the cell populations. So this technique provides an important method for studying the electrophysiology of the small cell, the tiny neurite and the cardiac arrhythmia, etc. Because this technique can also avoid the electromagnetic interferences, it uniquely provides an ideal means for studying the mechanisms such as cardiac defibrillation. In this paper the principles and the system structure of the optical mapping are introduced, its applications and future developments are also presented at the same time.
Animals ; Brain ; physiology ; Electrodes ; Electrophysiology ; methods ; Fluorescent Dyes ; Humans ; Membrane Potentials ; physiology ; Myocytes, Cardiac ; physiology ; Optics and Photonics

OBJECTIVETo observe the treatment and prognosis of optic nerve invasion in retinoblastoma (RB).

METHODThe children who had been diagnosed with unilateral RB and had received enucleation from January 2006 to December 2013 in our hospital were recruited. Tumor extension into the optic nerve were disclosed. Optic nerve involvement was classified into four grades according to the degree of invasion. Grade I is superficial invasion of the optic nerve head only, grade II is involvement up to and including the lamina cribrosa, grade III is involvement beyond the lamina cribrosa, and grade IV is involvement up to and including the surgical margin. Grade I and II are called invasion of the optic nerve before the sieve plate. Grade III and IV are called invasion of the optic nerve after the sieve plate. Other high-risk factors included extensive invasions of the choroid, sclera, anterior chamber, iris, and ciliary body. They were divided into two groups according to whether the merger of other high histopathologic risk factors. Treatment was delivered accordingly, and the prognosis of different degrees of optic nerve invasion was observed. The subjects were followed up for 6 months to 7 years (average: 43 months).

RESULTThere were 465 subjects in this study, including 279 boys and 186 girls. The right eye was affected in 260 patients and the left eye in 205 patients. The average time from onset of symptoms to visit was 2.7 months (range 1 day-24 months). Twenty-five patients died, resulting in an overall survival rate of 94.6%. The mortality rate of patients with optic nerve involvement with grade I was 0.4%, grade II was 1.0%, grade III was 8.7% was and grade IV was 60.9%. Of the 338 with invasion of the optic nerve before the sieve plate, two died of recurrence, with a survival rates of 99.4% (336/338). Of the 127 patients who had invasion of the optic nerve after the sieve plate, twenty-three died of recurrence, with a survival rate of 81.9% (104/127) , the difference was statistically significant (χ² = 52.299, P = 0.000). A total of 379 patients did not have any other merged pathology high-risk factors, 8 died, the mortality rate was 2.1%. Of the 86 patients who had complicated with other high-risk factors, 17 died, the mortality rate was 19.8%, the difference was statistically significant (χ² = 42.955, P = 0.000). Of the 338 patients, 304 had invasion of the optic nerve before the sieve plate had not merged other pathology high-risk factors, none died, of the 34 patients who had complicated with other pathology high-risk factors, 2 had died, the mortality rate was 5.9%, the difference was statistically significant (P = 0.010). Of the 127 patients with invasion of the optic nerve after the sieve plate, 76 had not complicated with other pathological high-risk factors, 9 of whom had died, the mortality rate was 11.8%, 51 had complicated with other pathological high-risk factors, 14 of whom had died, the mortality rate was 27.5%, outcomes did significantly differ between the two subgroups (χ² = 5.014, P = 0.025). Cox multivariate analysis showed that invasion of the retrolaminar optic nerve, surgical margin of the optic nerve and sclera were influential factors of colorectal cancer.

CONCLUSIONPatients with optic nerve invasion have an excellent outcome with current therapy. But for those whose resection margin was invaded, which has a high incidence of recurrence, chemotherapy is recommended for patients with postlaminar optic nerve involvement.

Child ; Female ; Humans ; Male ; Multivariate Analysis ; Neoplasm Invasiveness ; Neoplasm Recurrence, Local ; Optic Nerve Neoplasms ; pathology ; surgery ; Prognosis ; Retinoblastoma ; pathology ; surgery ; Retrospective Studies ; Survival Rate

On the basis of mammalian ventricular action potential model Noble98, and with the use of Runge-Kutta for solution, the Wenckebach periodicity phenomenon, the transmural heterogeneity of the ventricular myocardium and its rate dependence are studied. The results indicate that these inherent properties may, lead to temporal-space disorganized in the normal heart,and may become the underlying factors for arrhythmias. At the same time, in this study are established the basic methods for quantitative cellular electrophysiology which is essential for future studies on the mechanism of arrhythmia.
Action Potentials ; physiology ; Arrhythmias, Cardiac ; physiopathology ; Computer Simulation ; Electrophysiology ; Heart Conduction System ; physiology ; Heart Ventricles ; Humans ; Ion Channels ; metabolism ; Models, Cardiovascular ; Myocytes, Cardiac ; physiology

Focusing on the heart rate control mode of acceleration sensor based rate responsive pacemakers, this paper implemented the design of activity--heart rate prediction system. Bluetooth module was used as communication means in activity--heart rate prediction system, and the slave computer was used to complete the acceleration signal acquisition and processing, map from acceleration signal to the pacing rate signal, and achieve real-time transmission of acceleration signal and heart rate signal. The master computer fulfilled real-time display and recording of acceleration signal and heart rate signal, moreover, it achieved control function to the slave computer algorithm through classification of 6 parameters. The results of verification experiment showed that there was a significant relation between mapping heart rate and actual heart rate using linear mapping algorithm (R2 = 0.787, P < 0.001).
Algorithms ; Cardiac Pacing, Artificial ; methods ; Heart Rate ; physiology ; Humans ; Motor Activity ; Pacemaker, Artificial ; Signal Processing, Computer-Assisted

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