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.

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

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.

Objective:To improve the clinicians′ understanding of central nervous system (CNS) metastasis in children with solid tumors.Methods:The clinical data of 33 cases of CNS metastasis among 611 children with malignant solid tumors in the chest and abdomen from September 2005 to December 2016 in Beijing Tongren Hospital, Capital Medical University were retrospectively analyzed. The clinical characteristics, treatment and prognosis of metastasis were statistically analyzed according to different pathological types of malignant solid tumors in children with CNS metastasis.Results:Among the 611 children with malignant solid tumors in the chest and abdomen, 15 patients were neuroblastoma with CNS metastasis (5.9%, 15/264), 13 patients were hepatoblastoma with CNS metastasis (4.8%, 13/274), two cases were Wilms tumor with CNS metastasis (3.2%, 2/63), and three cases were clear cell sarcoma of the kidney with CNS metastasis (3/10). The onset age of the malignant solid tumors was 3-189 months, and the median age of onset was 26.5 months. The time from the diagnosis of primary malignant solid tumor to diagnosis of CNS metastasis was 0-100 months, and the median time of metastasis was 18 months. The neuroimaging features of CNS metastasis were as follows:30 cases with brain metastasis, three cases with meningeal metastasis, and five cases with spinal cord involvement. Cerebrospinal fluid cytology was positive in two cases (2/3). Of the 33 patients with CNS metastasis, five underwent intracranial tumor resection combined with radiotherapy and chemotherapy, two underwent surgery alone, three underwent radiotherapy alone, and 23 underwent chemotherapy alone. After a median follow-up of 36 months, the survival time of 33 malignant solid tumors with CNS metastasis was (16.96±3.19) months, and the overall survival rate of three years was only 14.7%. The survival time of the patients with intracranial tumor surgery combined with radiotherapy and chemotherapy, surgery alone, radiotherapy alone, and chemotherapy alone was (40.50±4.32), (3.00±0), (35.50±5.50) and (10.35±2.84) months, respectively; and the three-year overall survival rates were 50.0%, 0, 50.0% and 4.3%, respectively (χ 2=15.19, P=0.002). The prognosis of the patients with intracranial tumor resection combined with radiotherapy and chemotherapy was the best. Conclusions:The highest incidence of CNS metastasis in children with malignant solid tumors in the chest and abdomen was found in the clear cell sarcoma of the kidney. The prognosis of CNS metastasis was found to be poor. But the comprehensive therapy of intracranial tumor resection combined with radiotherapy and chemotherapy can prolong survival and improve prognosis.

Adolescent and young adult (AYA) non-Hodgkin lymphoma (NHL) is different from children and older adults in patients' clinical characteristics, pathological subtypes and genetic characteristics. The standard treatment regimen is still unclear currently. This article briefly describes the epidemiology, molecular biological features and prognostic factors of AYA-NHL, and highlights the curative effects of different treatment options in various subtypes of AYA-NHL, aiming to provide a basis for making clinical standard treatment plans.

Objective:To summarize the prognostic characteristics of hepatoblastoma in children undergoing pulmonary metastasectomy.Methods:The clinical data of 48 hepatoblastoma patients with pulmonary metastases who underwent pulmonary metastases resection in our hospital from January 1 2009 to December 31, 2017 were collected, and prognosis of these patients was analyzed.Results:Forty eight cases were diagnosed as hepatoblastoma with pulmonary metastasis, including 30 cases with pulmonary metastasis alone and 18 cases accompany with other high risk factors affecting prognosis. All the 48 patients underwent pulmonary metastasectomy, in which 43 patients were given pulmonary metastases resection completely and 5 patients were given partial resection of metastases. Twenty-five cases recurred after the first pulmonary metastasis resection(25/48, 52.1%), and 2 cases progressed. With the median follow-up time of 45.5 months, survival time of 48 patients with pulmonary metastasectomy was(83.59±7.01)months, and the 3-year overall survival rate was 58%. Of the groups those were patients with pulmonary metastasis alone and patients with other high risk factors affecting prognosis, the survival time and the 3-year overall survival rate showed a significant statistical differences[(95.89±8.19)months vs.(58.95±9.40)months; 79.4% vs.50%; χ2=4.849, P= 0.028)]. The survival time and 3-year survival rate of the two groups between with recurrence or progression and the group without recurrence or progression after pulmonary metastases resection were showed a significant difference[(56.84±7.22)months vs.(112.48±7.08)months; 55.6% vs.90.5%; χ2=11.03, P= 0.001)]. Results of COX regression analysis showed that the main risk factor affecting prognosis was pulmonary metastasis accompany with other high-risk factors for hepatoblastoma patients. The death risk of patients with pulmonary metastasis accompany with other high-risk factors was 3.424 times than that of patients without other high-risk factors( RR=3.424, 95% CI: 1.264~9.275). Conclusion:The overall prognosis of patients with pulmonary metastases is not good, and the proportion of postoperative recurrence is very high. Pulmonary metastasis accompanied with other high risk factors is the main risk factor affecting the prognosis of patients with pulmonary metastasectomy.

Objective:To study the relationship between high-risk factors with the diagnosis, treatment and prognosis of children with high-risk head and neck rhabdomyosarcoma (RMS).Methods:Children with high-risk RMS primarily found in head and neck were selected as research objects according to the criteria of RMS risk degree formulated by Children Oncology Group (COG) and Children′s Rhabdomyosarcoma Cooperative Group, Children′s Hematological Oncology Group, China Anti-Cancer Association (CCCG-RMS), and combined treatment including puncture pathology/surgery, chemotherapy and radiotherapy were performed.The relationship with primary site, age, pathology type and metastasis and prognosis were analyzed.Results:Twenty-nine patients were collected as research object, 17 cases (58.6%) of male, and 12 cases (41.4%) of female.The primary site: orbit was 7 patients (24.1%), and para-meningeal was 22 patients (75.9%). Clinical stage: 2 cases were stage Ⅲ (6.9%), and 27 cases were stage Ⅳ (93.1%). Followed up to December 31, 2018, 14 patients were dead, 15 patients were survival, and 10 patients were event free survival.The overall survival rate was 48.3%(15/29 cases), and the event free survival rate was 34.5%(10/29 cases). According to Kaplan- Merier survival curve analysis, the average overall survival time was (76.0±12.0) months, 95% confidence interval (95% CI): (53.5-93.2)months.The event free survival time was (62.5±10.6) months, 95% CI: (47.0-83.9)months. Conclusions:The prognosis of high-risk head and neck RMS is poor.The center system metastasis is cause of death.Thus, the main task is how to close follow-up and prevention of central nervous system invasion for improving prognosis.

Objective:To investigate the clinical features, diagnosis, treatment and prognosis of advanced clear cell sarcoma of kidney(CCSK) in children.Methods:The clinical data of 10 children with advanced CCSK hospitalized in Department of Pediatrics of Beijing Tongren Hospital, Capital Medical University from January 2014 to December 2017 were collected, and their clinical features, diagnosis, treatment and prognosis were analyzed retrospectively.Results:(1) Clinical features of CCSK: ten cases of CCSK included 6 boys and 4 girls, with the median onset age of 32 months; 7 cases were left CCSK and 3 cases were right CCSK.There were 9 cases of stage Ⅲ and 1 case of stage Ⅳ at the time of initial diagnosis, when 4 cases were misdiagnosed as other renal tumors at the time of initial diagnosis(40%, 4/10 cases). Five patients with stage Ⅲ CCSK had recurrence and metastasis during treatment and follow-up, and the main distant metastasis sites were lung, bone, liver and brain.(2) Treatment and prognosis of CCSK: seven cases received surgery combined with radiotherapy and chemotherapy, and 3 cases whose parents gave up treatment adopted non-standardized treatment.The median follow-up time was 33.5 months.Seven patients survived and 3 cases died.The 3-year overall survival rate of all 10 patients was 65.6%.The 3-year overall survival rate of stage Ⅲ was 74.1%, and that of stage Ⅳ was 0.The prognosis of stage Ⅲ was significantly better than that of stage Ⅳ( χ2=9, P=0.003). Among the 5 recurrent cases, only 1 case achieved completely remission, 2 cases achieved partially remission, 1 case suffered from disease progression and 1 case died.The 3 cases without recurrence were given standardized treatment of surgery, che-motherapy and radiotherapy, and all were completely remitted. Conclusions:CCSK is easy to be misdiagnosed, and the risk of recurrence and distant metastasis is high in stage Ⅲ patients during treatment and follow-up.Stage Ⅲ patients who actively receive standard treatment including surgery, chemotherapy and radiotherapy have good prognosis, while the mortality of patients with relapse and distant metastasis is high.