[A case of pulmonary aspergillus infection in underground coal mine workers].

The underground environment is dark and humid, and it is easy to breed pathogenic microorganisms. A lump in the right lung of a coal mine underground transport worker was found druing occupational health examination. CT examination showed that the lump was located in the posterior segment of the upper lobe of the right lung, with point strip calcification, liquefaction necrosis, and proximal bronchial stenosis and occlusion. MRI examination FS-T(2)WI and DWI showed "target sign", annular low signal around the central high signal, and low mixed signal around the periphery, and annular high signal in the isosignal lesions on T(1)WI. Then the pulmonary aspergillus infection was confirmed by pathology.

[Construction of artificial neural network model for predicting the efficacy of first-line FOLFOX chemotherapy for metastatic colorectal cancer].

Objective: To explore and establish an artificial neural network (ANN) model for predicting the efficacy of first-line FOLFOX chemotherapy for metastatic colorectal cancer. Methods: A set of FOLFOX chemotherapy data from a group of patients with metastatic colorectal cancer (mCRC) (GSE104645) was downloaded from the GEO database as a training set. According to the FOLFOX protocol, the efficacy was divided into two groups: the chemo-sensitive group (including complete response and partial response) and the chemo-resistant group (including stable disease and progressive disease), including 31 cases in the sensitive group and 23 in the resistant group. Then, chip data (accessible number: GSE69657) from Fujian Medical University Union Hospital were chosen as a test set. A total of 30 patients were enrolled in the study, including 13 in the sensitive group and 17 in the resistant group. The batch effect correction was performed on the expression values of the two sets of matrices using the R 3.5.1 software Combat package. The gene expression difference of sensitive and resistant group in GSE104645 was analyzed by the GEO2R platform. P<0.05 and the absolute value of log(2)FC>0.33 (FC abbreviation of fold change) were used as the threshold value to screen the drug resistance and sensitive genes of the FOLFOX regimen. An ANN was constructed using the multi-layer perceptron (MLP) to perform the FOLFOX regimen on the GSE104645 dataset. The GSE69657 expression matrix and clinical efficacy parameters were then used for retrospective verification. Receiver operating characteristic(ROC) curves were used to evaluate the test results and predictive power. Results: A total of 2, 076 differentially expressed genes in GSE104645 were selected, of which 822 genes were up-regulated and 1, 254 genes were down-regulated in the chemo-resistance group. The down-regulated genes were sensitive genes. GO analysis of the biological processes in which the differentially expressed genes were involved, revealed that they were mainly involved in the regulation of substance metabolism. A total of 39 genes were included in the final model construction. This was a neural network model with two hidden layers. The accuracy of predicting training samples and test samples was 75.7% and 76.5%, respectively, and the area under the ROC curve was 0.875. The chip data set of our department (GSE69657) was set as the test set, and the area under the ROC curve was 0.778. Conclusions: In this study, an artificial neural network model is successfully constructed to predict the efficacy of first-line FOLFOX regimen for metastatic colorectal cancer based on the microarray, and an independent external verification is also conducted. The model has good stability and well prediction efficiency. Besides, the results of this study suggest that the gene functions related to oxaliplatin resistance are mainly enriched in the regulation process of substance metabolism.

[The association of Bcl-2 gene polymorphism with the esophageal cancer and gastric cardia adenocarcinoma in Hebei Province].

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.

Selecting stage ypT0-1N0 for locally advanced rectal cancer following preoperative chemoradiotherapy: implications for potential candidates of organ-sparing management.

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.

[Effects of neoadjuvant chemoradiotherapy on the rates of sphincter preserving surgery in lower rectal cancer and analysis of their prognostic factors].

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.

[Prognostic factors of postoperative incisional surgical site infections for colorectal cancer].

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.

Analysis of changes in serum high t-PINP/ß-CTX ratio and risk of re-fracture after vertebral osteoporotic fracture surgery.

OBJECTIVE: This study's aim was to investigate the expression changes of total type I procollagen amino-terminal peptide (t-PINP) and type I collagen C-terminal peptide (ß-CTX) in serum after vertebral osteoporotic fracture surgery and the clinical value of predicting the risk of refracture. PATIENTS AND METHODS: The clinical data of 100 patients with vertebral osteoporotic fractures treated in our hospital from January 2019 to January 2020 were retrospectively analyzed, and the patients were divided into the control group (patients without re-fracture, n = 68) and the observation group (patients with re-fracture, n = 32) according to whether they had re-fracture at 2-year follow-up. The risk factors of postoperative re-fracture were analyzed using Multivariate logistic regression analysis. The serum contents of t-PINP, ß-CTX, osteocalcin (BGP), and calcium (Ca) were measured. Bone mineral density (BMD) was measured by bone densitometer. The correlation between the t-PINP/ß-CTX ratio and the bone metabolic index was analyzed by Pearson correlation. The area under the curve (AUC), sensitivity, and specificity of t-PINP/ß-CTX in predicting the risk of re-fracture were determined by the receiver operating characteristic (ROC) curve. RESULTS: There was a significant difference in age, the number of vertebral bodies with initial fracture, and whether there was leakage of bone cement between the two groups (p < 0.05). Age, the number of vertebral bodies with primary fracture, and the leakage of bone cement were risk factors affecting re-fracture after operation (p < 0.05). Compared with those in the control group, the level of t-PINP and the ratio of t-PINP/ß-CTX were higher, and the ß-CTX level was lower in the observation group (p < 0.05). The BGP level was higher, and the levels of BMD and Ca were lower in the observation group than those in the control group (p < 0.05). Pearson correlation analysis showed that t-PINP had a positive correlation with BGP (r = 0.222, p < 0.05). ß-CTX was positively correlated with BMD and Ca (r = 0.230, 0.269, p < 0.05). The ratio of t-PINP/ ß-CTX was negatively correlated with BMD and Ca (r = -0.621 and -0.660, p < 0.05), but positively correlated with BGP (r = 0.517, p < 0.05). ROC curve analysis showed that the AUC of t-PINP, ß-CTX, and the ratio of t-PINP/ß-CTX in predicting the risk of re-fracture after vertebral osteoporotic fracture surgery was 0.724, 0.736, and 0.838, respectively. CONCLUSIONS: The t-PINP/ß-CTX ratio was significantly correlated with the bone metabolic indexes in patients with vertebral osteoporotic fractures. The detection of the changes in its index can help predict the risk of postoperative re-fracture, providing a new idea for clinical assessment of the risk of postoperative re-fracture.

Novel ZFPM2/FOG2 variants in patients with double outlet right ventricle.

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.

[Gadolinium angiography of inner ear in patients with sudden deafness and its clinical analysis].

Objective: To observe the gadolinium imaging findings of inner ear in patients with sudden deafness and to analyze its clinical features. Methods: From November 2017 to July 2020, 21 patients with sudden deafness in the People's Hospital of Dongsheng District, Ordos City were selected as the research objects, including 14 males and 7 females, aged 36-76 years, with a median age of 50 years. The course of disease was 1-19 days, with an average of 5.5 days. The patients received audiology tests, laboratory examination, and intravenous gadolinium angiography, each of whom was scanned twice by 3D-FLAIR sequence: once before intravenous gadolinium injection, and once again 4.5-6.0 h after intravenous gadolinium injection. The following corresponding clinical treatment was given. The imaging manifestations and clinical features were observed. Results: Among 21 cases of sudden deafness in acute stage, the signal intensity of 11 cases was significantly higher than that of the contralateral ear, and 2 cases had vestibular labyrinthine hydrops. In laboratory examination, only 2 cases of total deafness had increased WBC count and faster erythrocyte sedimentation rate, and the rest had no abnormality. The hearing types of 21 patients with sudden deafness were: total deafness in 8 cases, flat decline in 10 cases, low frequency decline in 1 case, high frequency decline in 2 cases. The total effective rate was 57% (12/21). The hearing types of 11 patients with abnormal gadolinium angiography were total deafness in 5 cases, flat decline in 5 cases and high frequency decline in 1 case. The total effective rate was 64% (7/11). Conclusion: Gadolinium angiography is abnormal in some patients with sudden deafness, and the permeability of blood labyrinth barrier may be increased, which is worthy of further study.

[Identification of gene biomarkers to predict responses to neoadjuvant chemoradiotherapy in patients with rectal cancer and pathways enrichment analysis].

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.

Serum Cyr61 as a potential biomarker for diagnosis of colorectal cancer.

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.

[Analysis on epidemiology and spatial-temporal clustering of human brucellosis in Fujian province, 2011-2016].

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.

Paragonimiasis and the genus Paragonimus.

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.

Separation of Chinese Leishmania isolates into five genotypes by kinetoplast and chromosomal DNA heterogeneity.

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)

The characterization by isoenzyme electrophoresis of Leishmania isolated in the People's Republic of China.

Seven isolates of Leishmania from mainland China were characterized on the basis of their isoenzyme profiles for 10 enzymes. Five isolates were from human visceral leishmaniasis patients, and four of these showed isoenzyme patterns similar to the marker strain of Leishmania infantum, while one was similar to L. donovani sensu lato. One isolate was from a presumed reservoir host of human visceral leishmaniasis, the racoon dog Nyctereutes procyanoides, and was isoenzymically indistinguishable from L. infantum. An isolate of L. gerbilli from the great gerbil Rhombomys opimus was readily distinguishable from Old World marker strains and other Chinese leishmanias. This is the first report of the biochemical characterization of Chinese isolates of Leishmania.

Neural networks for convex hull computation.

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.

Degree of population diversity - a perspective on premature convergence in genetic algorithms and its Markov chain analysis.

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.

Nonlinear measures: a new approach to exponential stability analysis for Hopfield-type neural networks.

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.

Some efficient strategies for improving the eigenstructure method in synthesis of feedback neural networks.

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.

A competitive associative memory model and its dynamics.

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.