Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 46
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Zhonghua Wei Chang Wai Ke Za Zhi ; 22(12): 1183-1187, 2019 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-31874536

RESUMO

Objective: To screen out the potential gene biomarkers to predict responses to neoadjuvant chemoradiotherapy (CRT) in patients with rectal cancer and to explore the main downstream pathways of resistance. Methods: The gene expression profiles (GSE35452) of locally advanced rectal cancer undergoing neoadjuvant chemoradiotherapy from 46 specimens (24 responders, TRG 0/1, and 22 non-responders, TRG 2/3) were downloaded from the GEO database. The differentially expressed genes were identified to screen out the potential biomarkers by use of the GCBI platform. GO and KEGG pathways enrichment analysis were performed to integrate enrichment results of differentially expressed genes. Signal-signal interaction network was constructed and analyzed to screen out potential main downstream pathways. Results: A total of 1079 differentially expressed genes were screened, including 657 up-regulated and 422 down-regulated ones. Among these genes, REG4 had the maximum fold change value of -6.029 491. In GO term, these differentially expressed genes were mainly enriched in molecule metabolic process, cell cycle, DNA-dependent transcription, signal transduction and apoptotic process. The KEGG pathways enrichment analysis showed that the differentially expressed genes were enriched in 65 KEGG pathways, including metabolic pathways, cell cycle and metabolism pathways. Signal-signal interaction network analysis showed that MAPK signaling pathway and cell cycle pathway might play a determinant role in the development of neoadjuvant chemoradiotherapy resistance. Further analysis showed that CDKN1B, CDKN2A, RBL1, TFDP1, CCND2, CCNE2, CDC6 and CDK6 in cell cycle might induce chemoradiotherapy resistance by blocking G1/S phase cell cycle arrest, decreasing the apoptosis of tumor cells and increasing S phase ratio of chemoradiotherapy resistance. Conclusion: G1/S phase cell cycle arrest blocking plays an important role in the development of chemoradiotherapy resistance in patients with rectal cancer. Moreover, the key genes, such as REG4, may be useful in predicting responses to neoadjuvant chemoradiotherapy.


Assuntos
Pontos de Checagem do Ciclo Celular/genética , Resistencia a Medicamentos Antineoplásicos/genética , Marcadores Genéticos , Proteínas Associadas a Pancreatite/genética , Neoplasias Retais/genética , Neoplasias Retais/terapia , Quimiorradioterapia Adjuvante , Perfilação da Expressão Gênica , Humanos , Terapia Neoadjuvante , Neoplasias Retais/tratamento farmacológico , Neoplasias Retais/radioterapia , Resultado do Tratamento
2.
Zhonghua Yu Fang Yi Xue Za Zhi ; 53(11): 1119-1123, 2019 Nov 06.
Artigo em Chinês | MEDLINE | ID: mdl-31683398

RESUMO

Objective: To investigate the association between the promoter region-938 polymorphism of B-cell lymphoma/leukemia-2 (Bcl-2) gene and the esophageal cancer (EC) and gastric cardia adenocarcinoma (GCA) in Hebei Province. Methods: From 2007 to 2010, 145 esophageal cancer patients and 169 cardiaccancer patientsfrom the outpatient department of the Fourth Hospital of Hebei Medical Universitywereselected in a case group, and 195 non-tumor patients were selected in a control group during the same period. A questionnaire survey was used to collect information of research subjects. Pathological tissues were collected to extract genomic DNA and detect the genotype of bcl-2 gene -938. A multivariate logistic regression model was used to analyze the association between the bcl-2 gene locus 938 CC genotype and the EC and GCA. The interaction between age, gender, smoking, drinking, upper gastrointestinal family history and the bcl-2 gene locus 938 CC genotype was analyzed by likelihood ratio test. Results: The age of the esophageal and cardiac cancer groups was (56.3±8.3) and (57.1±8.4) years old, and that of the control group was (54.7±7.1) years old. The proportion of the bcl-2 gene locus 938 CC genotype in the esophageal group [48.3% (70/145)] and the cardiac cancer group [48.5% (82/169)] was higher than that in the control group [33.8% (66/195)] (both P values<0.05).Compared with the AA genotype, the risk of esophageal cancer and cardiac cancerin people with the CC genotype was 2.386 (1.20-4.76) and 2.564 (1.27-5.18) respectively. In the population with CC genotype, compared with the positive family history, drinking, and male, the negative family history, non-drinking, and female had a higher risk of esophageal cancer; compared with the non-smoking, negative family history, non-drinking and male, the smoking, positive family history, drinking, and female had a higher risk of cardiac cancer (all the P interaction values were <0.05). Conclusion: People with bcl-2 gene locus 938 CC genotype in Hebei Provincewere more likely to suffer from the esophageal and gastric cardia adenocarcinoma.


Assuntos
Adenocarcinoma/genética , Cárdia/patologia , Neoplasias Esofágicas/genética , Genes bcl-2/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único/genética , Neoplasias Gástricas/genética , Adenocarcinoma/epidemiologia , Adenocarcinoma/patologia , Idoso , Estudos de Casos e Controles , China/epidemiologia , Neoplasias Esofágicas/epidemiologia , Neoplasias Esofágicas/patologia , Feminino , Genótipo , Inquéritos Epidemiológicos , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Neoplasias Gástricas/epidemiologia , Neoplasias Gástricas/patologia
3.
Zhonghua Liu Xing Bing Xue Za Zhi ; 38(9): 1212-1217, 2017 Sep 10.
Artigo em Chinês | MEDLINE | ID: mdl-28910934

RESUMO

Objective: To analyze the epidemiological characteristics and spatial distribution of human brucellosis in Fujian province during 2011-2016, and provide evidence for the prevention and control of the disease. Methods: The surveillance data of human brucellosis in Fujian during 2011-2016 was analyzed with software R 3.3.1, ArcGIS 10.3.1, GeoDa 1.8.8 and SaTScan 9.4.3. Results: During 2011-2016, a total of 319 human brucellosis cases were reported, the incidence increased year by year (F=11.838, P=0.026) with the annual incidence of 0.14/100 000. The male to female rate ratio of the incidence was 2.50 ∶ 1. Farmers and herdsmen accounted for 57.37%. The incidence was 0.40/100 000 in Zhangzhou and 0.32/100 000 in Nanping, which were higher than other areas. The number of affected counties (district) increased from 12 in 2011 to 28 in 2016, showing a significant increase (F=13.447, P=0.021). The Moran's I of brucellosis in Fujian between January 2011 and December 2016 was 0.045, indicating the presence of a high value or low value clustering areas. Local spatial autocorrelation analysis showed that, high-high clustering area (hot spots) were distributed in Zhangpu, Longhai, Longwen, etc, while high-low clustering areas were distributed in Nan'an and Jiaocheng, etc. Temporal scanning showed that there were three clustering areas in areas with high incidence, the most possible clustering, occurring during January 1, 2013- December 31,2015, covered 6 counties, including Yunxiao, Pinghe, Longhai, etc, and Zhangpu was the center, (RR=7.96, LLR=92.62, P<0.001). Conclusions: The epidemic of human brucellosis in Fujian is becoming serious, and has spread to general population and non-epidemic areas. It is necessary to strengthen the prevention and control of human brucellosis in areas at high risk.


Assuntos
Brucelose/epidemiologia , Notificação de Doenças/estatística & dados numéricos , Análise Espaço-Temporal , China/epidemiologia , Análise por Conglomerados , Feminino , Humanos , Incidência , Masculino , Análise Espacial
4.
Clin Transl Oncol ; 19(4): 519-524, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27743169

RESUMO

PURPOSE: To determine the sensitivity and specificity of serum Cyr61 as a potential biomarker for the diagnosis of colorectal cancer (CRC) and to assess the association between serum Cyr61 level and CRC clinicopathological status. METHODS: We used an enzyme-linked immunosorbent assay to measure serum Cyr61 in patients with CRC, patients with colorectal adenomas, and healthy controls. We also analyzed the relationship between serum Cyr61 and clinicopathological features of CRC patients. The levels of serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were quantified using the Roche Cobas 6000 Analyzer. The sensitivity and specificity of Cyr61, CEA, CA19-9 and CEA + CA19-9 were evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The serum level of Cyr61 was significantly increased in CRC patients compared with colorectal adenoma patients and healthy controls (p < 0.001). Furthermore, the area under the ROC curve for Cyr61 was 0.935 (95 % confidence interval 0.902-0.968), higher than that for CEA + CA19-9 (0.827, 95 % confidence interval: 0.783-0.871). Use of a Cyr61 cutoff value of 92.0 pg/mL allowed distinguishing CRC patients and healthy controls with a sensitivity of 83 % and a specificity of 97 %. Among CRC patients, an elevated level of serum Cyr61 was significantly associated with more advanced TNM stage (p < 0.0042), lymph node metastasis (p < 0.0088), and vascular invasion (p = 0.0027). CONCLUSION: Cyr61 has potential as a serum biomarker for the diagnosis of CRC and for assessment of the clinicopathological status of CRC.


Assuntos
Adenoma/diagnóstico , Biomarcadores Tumorais/sangue , Neoplasias Colorretais/diagnóstico , Proteína Rica em Cisteína 61/sangue , Adenoma/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígeno CA-19-9/sangue , Antígeno Carcinoembrionário/sangue , Estudos de Casos e Controles , Neoplasias Colorretais/sangue , Ensaio de Imunoadsorção Enzimática , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Estadiamento de Neoplasias , Prognóstico , Curva ROC
5.
Zhonghua Wai Ke Za Zhi ; 54(6): 419-423, 2016 06 01.
Artigo em Chinês | MEDLINE | ID: mdl-27938574

RESUMO

Objectives: To identify independent factors of sphincter preserving surgery, and to evaluated whether preoperative chemoradiotherapy (CRT) improves the sphincter preservation rate for lower rectal cancers. Methods: A total of 541 consecutive patients who underwent curative surgery for locally advanced rectal cancer (cT3-4Nx or cTxN+ ) within 6 cm of the anal verge with or without neoadjuvant CRT in Department of Colorectal Surgery, Union Hospital, Fujian Medical University between September 2000 and September 2013 were reviewed. Of these, 333 patients underwent surgery alone (Non-CRT group) and 208 patients also received preoperative chemoradiotherapy (CRT group). Clinical data were retrospectively reviewed to determine the factors influencing sphincter preservation, and to evaluate sphincter preservation rate according to tumor height over 1-cm intervals. The categorical variables were compared using χ2 test and Fisher exact test. Continuous variables were compared using t test. Logistic regression was used to identify factors influencing sphincter preservation. A receiver operating characteristic (ROC) curve was constructed, and Youden's index was calculated to evaluate the predictive abilities of factors. Results: Multivariate analysis indicated that the independent factors influencing sphincter preservation were tumor height (OR=5.867, 95% CI: 4.155 to 8.285, P=0.000), pathological T stage (OR=0.688, 95% CI: 0.462 to 1.025, P=0.066), CRT (OR=2.088, 95% CI: 0.971 to 4.492, P=0.060) and histopathological type (OR=0.288, 95% CI: 0.136 to 0.611, P=0.001). The results of ROC analysis showed that the cut-off points for factors affecting sphincter preservation were as follows: (1) tumor height prior to CRT higher than 4.5 cm, (2) not mucinous or signet ring adenocarcinoma, (3) pathological T stage higher than T3, (4) had received preoperative CRT. In an analysis according to tumor height, the sphincter preservation rate was higher in CRT group only when tumor was located in 3.0 to 3.9 cm and 4.0 to 4.9 cm from the annal verge (3.0 to 3.9 cm, 59.4% vs. 2.8%, χ2=26.138, P=0.000; 4.0 to 4.9 cm, 76.9% vs. 37.9%, χ2=10.563, P=0.001). Conclusions: There is a large increased rate of sphincter preservation when patients meet the following conditions: (1) tumor height prior to CRT higher than 4.5 cm, (2) not mucinous or signet ring adenocarcinoma, (3)pathological T stage higher than T3, (4) had received preoperative CRT. Only when tumors are between 3 and 5 cm from the anal verge, CRT could increase the rate of anal sphincter preservation.


Assuntos
Adenocarcinoma/cirurgia , Adenocarcinoma/terapia , Canal Anal/patologia , Quimiorradioterapia/métodos , Colectomia/métodos , Neoplasias Retais/cirurgia , Neoplasias Retais/terapia , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Procedimentos Cirúrgicos do Sistema Digestório , Humanos , Modelos Logísticos , Análise Multivariada , Terapia Neoadjuvante , Estadiamento de Neoplasias , Prognóstico , Neoplasias Retais/mortalidade , Neoplasias Retais/patologia , Estudos Retrospectivos , Resultado do Tratamento
6.
Zhonghua Wai Ke Za Zhi ; 54(6): 424-428, 2016 06 01.
Artigo em Chinês | MEDLINE | ID: mdl-27938575

RESUMO

Objective: To explore the prognostic factors of postoperative incisional surgical site infections (I-SSI) for colorectal cancer. Methods: Clinical data of 2 385 colorectal cancer patients undergoing resection by the same surgical team in Department of Colon and Rectum Surgery, Fujian Medical University Union Hospital from January 2000 to February 2014 was analyzed retrospectively. There were 1 421 male and 964 female patients, with a mean age of (59±13) years. Univariate analysis and multivariate Logistic regression analysis were performed for independent prognostic factors of I-SSI. Results: The I-SSI occurred in 77 patients (3.23%). The results of univariate analysis showed that there were statistical differences in body mass index (t=-3.356), operation time (t=-3.609), length of incision (t=-5.492), radical operation (χ2=8.963), laparoscopic surgery (χ2=25.884), combined evisceration (χ2=6.349) and intraoperative blood infusion (χ2=4.176) between two groups (all P<0.05) . The results of multivariate Logistic regression analysis showed that independent prognostic factors of I-SSI were identified to be body mass index (OR=1.087, 95%CI: 1.023 to 1.155, P=0.007), operation time (OR=1.007, 95%CI: 1.002 to 1.012, P=0.006), preoperative chemoradiotherapy (OR=2.434, 95%CI: 1.099 to 5.393, P=0.028) and combined evisceration (OR=2.596, 95%CI: 1.060 to 6.357, P=0.037). The independent protective prognostic factor of I-SSI was identified to be the laparoscopic surgery (OR=0.386, 95%CI: 0.170 to 0.877, P=0.023). Conclusions: Body mass index, operation time, preoperative chemoradiotherapy and combined evisceration are identified to be independent prognostic factors for I-SSI. High-risk patients should receive individualized perioperative intervention. Nevertheless, the laparoscopic surgery can decrease the incidence of I-SSI.


Assuntos
Neoplasias Colorretais/cirurgia , Cirurgia Colorretal , Laparoscopia , Complicações Pós-Operatórias/etiologia , Infecção da Ferida Cirúrgica/complicações , Adulto , Idoso , Índice de Massa Corporal , China/epidemiologia , Neoplasias Colorretais/complicações , Procedimentos Cirúrgicos do Sistema Digestório , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Período Pós-Operatório , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Infecção da Ferida Cirúrgica/epidemiologia
7.
Colorectal Dis ; 18(10): 989-996, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26880193

RESUMO

AIM: Local excision or a wait-and-see policy may offer the possibility of organ preservation for locally advanced rectal cancer (LARC) after preoperative chemoradiotherapy (CRT). Identifying associated factors of good responders (GR) with stage ypT0-1N0 would probably influence the selection of potential candidates who were theoretically eligible for organ-sparing management. This study was to establish a scoring system to select stage ypT0-1N0 for LARC following preoperative CRT. METHOD: Between 2009 and 2014, 262 patients with middle and low LARC were treated with CRT and radical surgery. Clinicopathological data which were found to be significantly associated with GR were incorporated into a scoring system. RESULTS: Fifty-seven (21.8%) patients were GR with stage ypT0-1N0 in the operative specimen. Multivariate analyses indicated that a low level of pretreatment carcinoembryonic antigen (CEA) and post-treatment CEA <2.55 ng/ml (P = 0.008 and P = 0.009 respectively) and long-axis diameter of residual tumours (P = 0.006) were independently associated with stage ypT0-1N0. The three factors were incorporated into a scoring system. Using receiver operating characteristic curve analysis, we determined a cutoff value of -0.3 for scores, at which the system's sensitivity was 71.9% and specificity 73.1%. When applied to testing samples, the sensitivity was 74.1% and specificity 76.2%. CONCLUSION: We demonstrated that low levels of pretreatment and post-treatment CEA and the long-axis diameter of residual tumours were associated with stage ypT0-1N0 for LARC after CRT. Therefore, the three-factor scoring system may be used to select potential candidates for organ-sparing management.


Assuntos
Tratamentos com Preservação do Órgão/métodos , Seleção de Pacientes , Neoplasias Retais/terapia , Quimiorradioterapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Terapia Neoadjuvante , Estadiamento de Neoplasias , Curva ROC , Neoplasias Retais/patologia , Valores de Referência , Estudos Retrospectivos , Sensibilidade e Especificidade , Resultado do Tratamento
8.
Clin Genet ; 82(5): 466-71, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21919901

RESUMO

Congenital heart defects (CHDs) occur in about 0.5-1% of all newborns and are the most common birth defects. Double outlet right ventricle (DORV) accounts for approximately 1-3% of all CHDs. Similar to Tetralogy of Fallot (TOF), DORV is a subtype of contruncal heart defects (CTDs) and is anatomically characterized by a malposition of the great arteries. We described a boy with chromosomal translocation: 46, XY t (8; 18) (q22; q21) that may disrupts the ZFPM2/FOG2 locus. The coding sequences of ZFPM2/FOG2 were determined in 38 patients with sporadic DORV, 95 patients with TOF, and 12 patients with transposition of the great arteries. Five DNA sequence variants affecting variably conserved residues of ZFPM2/FOG2 were identified in patients with TOF type or ventricular septal defect type of DORV. Three novel mutations (p.V339I, p.K737E, and p.A611T) were reported for the first time. The other two mutations (p.M703L and p.Q889E) were reported in patients with congenital diaphragmatic hernia but not in patients with CHD. Our finding suggests that variants of the ZFPM2/FOG2 gene might be a common cause of DORV.


Assuntos
Proteínas de Ligação a DNA/genética , Dupla Via de Saída do Ventrículo Direito/genética , Variação Genética , Fatores de Transcrição/genética , Adolescente , Sequência de Aminoácidos , Grupo com Ancestrais do Continente Asiático , Criança , Pré-Escolar , Cromossomos Humanos , Estudos de Coortes , Éxons , Feminino , Deleção de Genes , Frequência do Gene , Loci Gênicos , Hérnias Diafragmáticas Congênitas , Humanos , Cariotipagem/métodos , Masculino , Dados de Sequência Molecular , Mutação , Análise de Sequência de DNA , Tetralogia de Fallot/genética
9.
Environ Monit Assess ; 87(3): 235-54, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12952354

RESUMO

As the health impact of air pollutants existing in ambient addresses much attention in recent years, forecasting of air pollutant parameters becomes an important and popular topic in environmental science. Airborne pollution is a serious, and will be a major problem in Hong Kong within the next few years. In Hong Kong, Respirable Suspended Particulate (RSP) and Nitrogen Oxides NOx and NO2 are major air pollutants due to the dominant diesel fuel usage by public transportation and heavy vehicles. Hence, the investigation and prediction of the influence and the tendency of these pollutants are of significance to public and the city image. The multi-layer perceptron (MLP) neural network is regarded as a reliable and cost-effective method to achieve such tasks. The works presented here involve developing an improved neural network model, which combines the principal component analysis (PCA) technique and the radial basis function (RBF) network, and forecasting the pollutant levels and tendencies based in the recorded data. In the study, the PCA is firstly used to reduce and orthogonalize the original input variables (data), these treated variables are then used as new input vectors in RBF neural network model established for forecasting the pollutant tendencies. Comparing with the general neural network models, the proposed model possesses simpler network architecture, faster training speed, and more satisfactory predicting performance. This improved model is evaluated by using hourly time series of RSP, NOx and NO2 concentrations collected at Mong Kok Roadside Gaseous Monitory Station in Hong Kong during the year 2000. By comparing the predicted RSP. NOx and NO2 concentrations with the actual data of these pollutants recorded at the monitory station, the effectiveness of the proposed model has been proven. Therefore, in authors' opinion, the model presented in the paper is a potential tool in forecasting air quality parameters and has advantages over the traditional neural network methods.


Assuntos
Poluentes Atmosféricos/análise , Modelos Teóricos , Dióxido de Nitrogênio/análise , Óxidos de Nitrogênio/análise , Cidades , Análise Custo-Benefício , Monitoramento Ambiental/economia , Monitoramento Ambiental/métodos , Previsões , Hong Kong , Tamanho da Partícula , Sensibilidade e Especificidade
10.
Artigo em Inglês | MEDLINE | ID: mdl-18238240

RESUMO

As a typical combinatorial optimization problem, the traveling salesman problem (TSP) has attracted extensive research interest. In this paper, we develop a self-organizing map (SOM) with a novel learning rule. It is called the integrated SOM (ISOM) since its learning rule integrates the three learning mechanisms in the SOM literature. Within a single learning step, the excited neuron is first dragged toward the input city, then pushed to the convex hull of the TSP, and finally drawn toward the middle point of its two neighboring neurons. A genetic algorithm is successfully specified to determine the elaborate coordination among the three learning mechanisms as well as the suitable parameter setting. The evolved ISOM (eISOM) is examined on three sets of TSP to demonstrate its power and efficiency. The computation complexity of the eISOM is quadratic, which is comparable to other SOM-like neural networks. Moreover, the eISOM can generate more accurate solutions than several typical approaches for TSP including the SOM developed by Budinich, the expanding SOM, the convex elastic net, and the FLEXMAP algorithm. Though its solution accuracy is not yet comparable to some sophisticated heuristics, the eISOM is one of the most accurate neural networks for the TSP.

11.
Artigo em Inglês | MEDLINE | ID: mdl-18238244

RESUMO

In this paper, a novel methodology called a reference model approach to stability analysis of neural networks is proposed. The core of the new approach is to study a neural network model with reference to other related models, so that different modeling approaches can be combinatively used and powerfully cross-fertilized. Focused on two representative neural network modeling approaches (the neuron state modeling approach and the local field modeling approach), we establish a rigorous theoretical basis on the feasibility and efficiency of the reference model approach. The new approach has been used to develop a series of new, generic stability theories for various neural network models. These results have been applied to several typical neural network systems including the Hopfield-type neural networks, the recurrent back-propagation neural networks, the BSB-type neural networks, the bound-constraints optimization neural networks, and the cellular neural networks. The results obtained unify, sharpen or generalize most of the existing stability assertions, and illustrate the feasibility and power of the new method.

13.
IEEE Trans Neural Netw ; 12(2): 360-70, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-18244390

RESUMO

In this paper, a new concept called nonlinear measure is introduced to quantify stability of nonlinear systems in the way similar to the matrix measure for stability of linear systems. Based on the new concept, a novel approach for stability analysis of neural networks is developed. With this approach, a series of new sufficient conditions for global and local exponential stability of Hopfield type neural networks is presented, which generalizes those existing results. By means of the introduced nonlinear measure, the exponential convergence rate of the neural networks to stable equilibrium point is estimated, and, for local stability, the attraction region of the stable equilibrium point is characterized. The developed approach can be generalized to stability analysis of other general nonlinear systems.

14.
Adv Parasitol ; 42: 113-222, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10050273

RESUMO

The review concentrates on literature that has appeared since the 1960s. Since then, numerous species of Paragonimus have been described, mainly from Asia but also from Africa and the Americas. Some of these cause disease in humans. Recent information on life cycles and routes of transmission is summarized. All described species and their hosts are listed, with synonyms where known. For well-known species such as Paragonimus westermani, subspecific taxa and strains are reviewed and genetic studies discussed. Paragonimiasis in humans and experimental animals is discussed with emphasis on clinical manifestations and pathology, diagnosis, immune interactions with the host, treatment and public health issues.


Assuntos
Paragonimíase/parasitologia , Paragonimus/classificação , Animais , Animais Domésticos/parasitologia , Gatos , Cães , Interações Hospedeiro-Parasita , Humanos , Moluscos/parasitologia , Paragonimíase/diagnóstico , Paragonimíase/imunologia , Paragonimíase/prevenção & controle , Paragonimus/anatomia & histologia , Paragonimus/crescimento & desenvolvimento , Ratos
15.
Artigo em Inglês | MEDLINE | ID: mdl-18255992

RESUMO

We consider an online string matching problem in which we find all the occurrences of a pattern of m characters in a text of n characters, where all the characters of the pattern are available before processing, while the characters of the text are input one after the other. We propose a space-time optimal parallel algorithm for this problem using a neural network approach, This algorithm uses m McCulloch-Pitts neurons connected as a linear array. It processes every input character of the text in one step and hence it requires at most n iteration steps.

16.
IEEE Trans Neural Netw ; 8(3): 601-11, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-18255663

RESUMO

Computing convex hull is one of the central problems in various applications of computational geometry. In this paper, a convex hull computing neural network (CHCNN) is developed to solve the related problems in the N-dimensional spaces. The algorithm is based on a two-layered neural network, topologically similar to ART, with a newly developed adaptive training strategy called excited learning. The CHCNN provides a parallel online and real-time processing of data which, after training, yields two closely related approximations, one from within and one from outside, of the desired convex hull. It is shown that accuracy of the approximate convex hulls obtained is around O[K(-1)(N-1/)], where K is the number of neurons in the output layer of the CHCNN. When K is taken to be sufficiently large, the CHCNN can generate any accurate approximate convex hull. We also show that an upper bound exists such that the CHCNN will yield the precise convex hull when K is larger than or equal to this bound. A series of simulations and applications is provided to demonstrate the feasibility, effectiveness, and high efficiency of the proposed algorithm.

17.
IEEE Trans Neural Netw ; 8(5): 1165-76, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-18255718

RESUMO

In this paper, a concept of degree of population diversity is introduced to quantitatively characterize and theoretically analyze the problem of premature convergence in genetic algorithms (GAs) within the framework of Markov chain. Under the assumption that the mutation probability is zero, the search ability of GA is discussed. It is proved that the degree of population diversity converges to zero with probability one so that the search ability of a GA decreases and premature convergence occurs. Moreover, an explicit formula for the conditional probability of allele loss at a certain bit position is established to show the relationships between premature convergence and the GA parameters, such as population size, mutation probability, and some population statistics. The formula also partly answers the questions of to where a GA most likely converges. The theoretical results are all supported by the simulation experiments.

18.
IEEE Trans Neural Netw ; 7(1): 233-45, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-18255576

RESUMO

Two efficient strategies are proposed for improving the eigenstructure method from the best approximation projector point of view. Interpreted as two complementary best approximation projectors, the method is reformulated in a much more simplified form. We develop a new synthesis procedure through constructing the related best approximation projectors by using a simple recursive formula, which improves on the existing eigenstructure method not only in the significant reduction of the computational complexity but also in the incorporation of the learning capability comparable to the outer product method. The networks designed by the present procedure outperform those designed by some other known methods. We also propose a new forgetting algorithm for deleting any specific existing memories in a synthesized network. The algorithm performs efficiently and reliably, which particularly eliminates the overforgetting drawback of the Yen-Michel algorithm (1991, 1992). The feasibility and effectiveness of the algorithm are supported by theoretical analysis and computer simulations.

19.
IEEE Trans Neural Netw ; 6(4): 929-40, 1995.
Artigo em Inglês | MEDLINE | ID: mdl-18263381

RESUMO

Conventional associative memory networks perform "noncompetitive recognition" or "competitive recognition in distance". In this paper a "competitive recognition" associative memory model is introduced which simulates the competitive persistence of biological species. Unlike most of the conventional networks, the proposed model takes only the prototype patterns as its equilibrium points, so that the spurious points are effectively excluded. Furthermore, it is shown that, as the competitive parameters vary, the network has a unique stable equilibrium point corresponding to the winner competitive parameter and, in this case, the unique stable equilibrium state can be recalled from any initial key.

20.
Am J Trop Med Hyg ; 50(6): 763-70, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8024072

RESUMO

Leishmaniasis remains endemic in China, especially in the west and northwest frontier regions in central Asia. Epidemic outbreaks of both visceral and cutaneous forms of the disease have become a serious concern in view of such events occurring in neighboring countries. In the present study, we have begun to characterize available parasites as an initial step in understanding the epidemiology of leishmaniasis in central Asia. Nineteen Leishmania isolates collected since the 1950s from epidemiologically different foci in China were separated into five genotypes (Groups I-V) based on their polymorphisms in both kinetoplast (kDNA) and nuclear (nDNA) DNAs. Both kDNA and nDNA are conserved in Group I, which consists of six isolates, i.e., five cases of human kala-azar and one case of canine leishmaniasis isolated from three distant foci more than 30 years apart. In contrast, both kDNA and nDNA are heterogeneous in Group II, consisting of 10 isolates scattered in the plain area from the eastern coast to the western desert. This group includes five kala-azar cases, one post-kala-azar dermal leishmaniasis case, two sand fly isolates, and two canine isolates. The remaining three groups (III-V), two from great gerbils (Rhombomys opimus) and one from a kala-azar case, differ among themselves and from the aforementioned groups. Groups I, II/III, IV, and V contain isolates that have been recognized epidemiologically or typed isoenzymatically as L. donovani s.l., L. infantum s.l., L. turinica, and L. gerbilli, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
DNA de Cinetoplasto/análise , DNA de Protozoário/análise , Leishmania/classificação , Leishmaniose/parasitologia , Animais , Sequência de Bases , China , Primers do DNA/química , Sondas de DNA , Genótipo , Humanos , Leishmania/genética , Dados de Sequência Molecular , Hibridização de Ácido Nucleico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA