Sensitivity analysis applied to the construction of radial basis function networks

Conventionally, a radial basis function (RBF) network is constructed by obtaining cluster centers of basis function by maximum likelihood learning. This paper proposes a novel learning algorithm for the construction of radial basis function using sensitivity analysis. In training, the number of hidden neurons and the centers of their radial basis functions are determined by the maximization of the output's sensitivity to the training data. In classification, the minimal number of such hidden neurons with the maximal sensitivity will be the most generalizable to unknown data. Our experimental results show that our proposed sensitivity-based RBF classifier outperforms the conventional RBFs and is as accurate as support vector machine (SVM). Hence, sensitivity analysis is expected to be a new alternative way to the construction of RBF networks.

Outcome of late surgical treatment in patients with incomplete paraplegia due to spinal degenerative diseases

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To assess the outcome of late surgical intervention in patients with incomplete paraplegia due to spinal degenerative diseases.

SETTING

Three men and four women with cervical or thoracic spinal degenerative diseases, who preoperatively were unable to walk for more than 6 months in Mie prefecture, Japan.

METHODS

Review of clinical records and questionnaire survey regarding the walking ability of patients 2 years after surgery.

RESULTS

All seven patients were unable to walk postoperatively.

CONCLUSION

A late surgical intervention may not lead to functional recovery in patients with spinal degenerative disease who were unable to walk for at least 6 months.

The incidence of deep vein thrombosis after hip and knee arthroplasties in Japanese patients: a prospective study

PURPOSE

To document the incidence of proximal deep vein thrombosis and pulmonary embolism in 58 consecutive Japanese patients undergoing total hip arthroplasty or total knee arthroplasty.

METHODS

Patients were routinely examined for proximal deep vein thrombosis by B-mode ultrasonography before and after surgery. Those patients who had ultrasonographic findings of deep vein thrombosis were also investigated for pulmonary embolism by ventilation-perfusion lung scan.

RESULTS

The incidence of deep vein thrombosis after total hip arthroplasty and total knee arthroplasty were 9.1% and 4.0% respectively, and the incidence of pulmonary embolism were 3.0% and 0%, respectively. There were no cases of fatal pulmonary embolism.

CONCLUSION

The incidence of deep vein thrombosis and pulmonary embolism in Japanese patients may have increased over the last few decades.

Interactions between landscape changes and host communities can regulate Echinococcus multilocularis transmission

An area close to the Qinghai-Tibet plateau region and subject to intensive deforestation contains a large focus of human alveolar echinococcosis while sporadic human cases occur in the Doubs region of eastern France. The current review analyses and compares epidemiological and ecological results obtained in both regions. Analysis of rodent species assemblages within quantified rural landscapes in central China and eastern France shows a significant association between host species for the pathogenic helminth Echinococcus multilocularis, with prevalences of human alveolar echinococcosis and with land area under shrubland or grassland. This suggests that at the regional scale landscape can affect human disease distribution through interaction with small mammal communities and their population dynamics. Lidicker's ROMPA hypothesis helps to explain this association and provides a novel explanation of how landscape changes may result in increased risk of a rodent-borne zoonotic disease.

[Multivariate analysis for prognostic predictors in non-small cell lung cancer]

BACKGROUND

To determine the prognostic predictors for non-small cell lung cancer ( NSCLC) with multivariate analysis.

METHODS

From 1981 to 1994, 158 patients with NSCLC had been treated by surgery alone or combined with radiotherapy and/ or chemotherapy . Their clinical characteristics were collected. All histological slides were reviewed to evaluate the histological type, tumor differentiation and vascular and lymphatic vessel invasion. Oncoprotein overexpressions were measured by immunohistochemistry assay ( ABC) , including Pan-ras, c-myc, c-erb B2, EGFR and p53. PCNA was also measured by ABC. The endpoints for prognosis consisted of survival, local control and distant metastasis. They were calculated by Kaplan-Meier method with Log-rank test determining the difference between subgroups. Cox model was used for multivariate analysis. The prognostic index ( PI) was calculated basing on the results of multivariate analysis, then the high risk group was determined by PI.

RESULTS

The overall actual 5-year survival rate was 44%. The unfavorable predictors were late T and N of TNM stage ( P = 0. 025 and < 0. 001) , lymphatic vessel invasion ( P= 0. 002) and multi-oncoprotein overexpression ( P= 0. 018) . The overall median of PI was 1. 71( 0. 23-3. 75) . The patients were divided into three groups: good prognosis group ( 42 cases, PI ≤ 1. 3) , moderate prognosis group ( 63 cases, 1. 3 < PI ≤ 2. 2) and bad prognosis group ( 53 cases, PI > 2. 2) . There was significant difference in survival rate among the three groups ( P < 0. 001) , 5-year survival rate was 77%, 45% and 21%, respectively.

CONCLUSIONS

The unfavorable predictors are late T, late N, lymphatic vessel invasion and multi-oncoprotein overexpression. PI could be used to determine the high risk group in patients with NSCLC.

The clinically variable R40H mutant ornithine carbamoyltransferase shows cytosolic degradation of the precursor protein in CHO cells

Ornithine carbamoyltransferase (OCT) deficiency is now frequently found in adults with hyperammonaemia affected by mutations that cause partial deficiency of this urea cycle enzyme. One of these mutations (R40H) has occurred in several families and has been found also in asymptomatic relatives. To better understand the phenotypic heterogeneity of this recurrent mutation, we investigated the biological properties of the mutant protein. Using 35S labelling, the import and processing of the R40H mutant OCT protein was investigated in intact CHO cells and in isolated rat liver mitochondria and compared to the wild type and R141Q mutant that causes complete enzyme deficiency. The R40H OCT protein seems to be imported and processed by the mitochondria in a manner similar to that of wild type. However, it is consistently degraded to a smaller fragment in the intact cells, unlike the wild type and R141Q mutant. The mature form of the enzyme is not susceptible to degradation. These data, obtained in CHO cells, suggest that deficiency in OCT enzymatic function conferred by the R40H mutation is likely caused by enhanced degradation of the preprotein in the cytosol. We propose therefore that variation in the rate of OCT turnover is responsible for the heterogeneity of the clinical phenotype in these patients.

[Quantitative analysis of the expression of insulin receptor and tyrosine protein kinase of patients with hepatic cirrhosis]

OBJECTIVE

To investigate the relationship between the expression of insulin receptor (IR) and the content of tyrosine protein kinase (TPK) in patients with hepatic cirrhosis.

METHODS

Glucose tolerance test (GTT), insulin, c-peptide, insulin antibodies in serum, the expression of IR and TPK were quantitively analysed in patients with hepatic cirrhosis. The amount of IR and TPK was evaluated by immunohistochemical quantitative analysis using image analyzer in 12 patients with positive HBV marks and cirrhosis. Insulin and c-peptide in serum were determined by immunoenzymemetric assay (IEMA) and insulin antibodies in serum determined by RIA.

RESULTS

IR amount in normal and abnormal GTT patients with hepatic cirrhosis was signifficantly less than that in control group (P<0.01). TPK amount in liver of patitents with abnormal GTT was less than that of normal GTT (P<0.01).

CONCLUSIONS

IR decreases in cirrhotic patients. Abnormal GTT has relation to reducing TPK activity.

[Clinicopathological and molecular genetic analysis in Chinese typical hereditary nonpolyposis colorectal cancer pedigrees]

OBJECTIVE

To investigate the clinicopathological and molecular genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees.

METHODS

Four Chinese HNPCC pedigrees were studied using microdissection, microsatellite instability analysis, immunohistochemistry staining and direct DNA sequencing for hMSH2 and hMLH1 genes.

RESULTS

All five tumor tissues from 4 probands showed high level of microsatellite instability at more than 2 loci(RER + phenotype). Three of 4 cases lost hMSH2 protein expression and one case showed no hMLH1 protein expression. Three pathological germline mutations (2 on hMSH2 and 1 on hMLH1) were identified.

CONCLUSIONS

Chinese typical HNPCC kindreds showed relatively frequent germline mutations of mismatch repair genes. Microsatellite instability analysis and immunohistochemistry staining might be the effective screening methods before direct DNA sequencing for the detection of mismatch repair genes. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC kindreds.

[Experimental study on repair of bile duct defects with expanded polytetrafluoroethylene]

OBJECTIVE

To explore the possibility of repair of the extensive bile duct injuries with expanded polytetrafluoroethylene (ePTFE).

METHODS

A total of 36 local healthy hybrid dogs were employed to establish bile duct injury models by means of partial removal of bile duct (group A, 14 dogs), excision of a segmental duct (group B, 10 dogs), and ligation of the lower part of common bile duct(group C, 5 dogs; group D, 7 dogs). Group A were patched with ePTFE mesh, group B replaced by ePTFE tube. Interposition of the grafts between gallbladder and duedenum or jejunum was performed on group C and group D. The animals' postoperative performance status were evaluated. Cholangiography was used to define the patency of bile ducts. Tissues of bile ducts and liver were taken at 3 days, 2, 4, 8, 12 and 52 weeks for microscopic and ultrastructural examination to observe the healing process of bile duct and morphological changes in the liver.

RESULTS

Group A with ePTFE patch covered by epithelium had a high patency rate of 75%(9/12) and pathological damages were not found in the liver. The patency rate of group B was merely 40%(4/10), to some extent, accompanying damages in the liver. The grafts of group C and group D were fully expelled, ultimately leading to cystic-duodenal or cystic-jejunal fistulas formation.

CONCLUSION

The study suggests that application of ePTFE patch to repair bile duct defects is feasible.

[Determination of podophyllotoxin lignans in Dysosma and its allied plants]

The existence of podophyllotoxin lignans in Dysosma versipellis and its allied plants was analyzed by twice developing TLC, and the content by chromotropic-colorimetric assay. The results showed that podophyllotoxin lignans exist in the rhizoma, radix, stem and leaf of Dysosma versipellis and its allied plants. The total lignans content is 2%-7%, and there is a big variation between different species. The total lignans content of Dysosma versipellis is related to the habitat.

Crystallization and preliminary X-ray crystallographic studies of wild-type human ornithine transcarbamylase and two naturally occurring mutants at position 277

Wild-type human ornithine transcarbamylase (OTCase) and two mutants (R277Q and R277W) that cause 'late-onset' hyperammonemia were crystallized and a preliminary structure determination was carried out. The unliganded wild-type enzyme crystallizes in the cubic space group I23, with unit-cell parameters a = b = c = 203.4 A. R277Q crystallizes in two crystal forms under the same crystallization conditions. One crystal form is isomorphous to that of unliganded wild-type crystals, with unit-cell parameters a = b = c = 202.2 A. The second form also belongs to a cubic space group, P4(3)32, but has unit-cell parameters a = b = c = 139.8 A. R277W crystals are isomorphous to the second crystal form of R277Q, with unit-cell parameters a = b = c = 138.7 A. None of these crystal forms is isomorphous to other crystal forms of OTCase that have been studied. The structures in both crystal forms have been solved using molecular replacement. In the first crystal form there are two monomers in the asymmetric unit, corresponding to a solvent content of 75%. Because of its high molecular and crystal symmetry and the presence of non-crystallographic symmetry, this structure could not be solved with AMoRe or X-PLOR, but was solved successfully with COMO. There is only one monomer in the asymmetric unit in the second crystal form, corresponding to a solvent content of 62%. This structure was successfully solved with AMoRe.

Human ornithine transcarbamylase: crystallographic insights into substrate recognition and conformational changes

Two crystal structures of human ornithine transcarbamylase (OTCase) complexed with the substrate carbamoyl phosphate (CP) have been solved. One structure, whose crystals were prepared by substituting N-phosphonacetyl-L-ornithine (PALO) liganded crystals with CP, has been refined at 2.4 A (1 A=0.1 nm) resolution to a crystallographic R factor of 18.4%. The second structure, whose crystals were prepared by co-crystallization with CP, has been refined at 2.6 A resolution to a crystallographic R factor of 20.2%. These structures provide important new insights into substrate recognition and ligand-induced conformational changes. Comparison of these structures with the structures of OTCase complexed with the bisubstrate analogue PALO or CP and L-norvaline reveals that binding of the first substrate, CP, induces a global conformational change involving relative domain movement, whereas the binding of the second substrate brings the flexible SMG loop, which is equivalent to the 240s loop in aspartate transcarbamylase, into the active site. The model reveals structural features that define the substrate specificity of the enzyme and that regulate the order of binding and release of products.

Visualizing filamentous actin on lipid bilayers by atomic force microscopy in solution

The surface structure of actin filaments (F-actin) was visualized at high resolution, by atomic force microscopy (AFM) in aqueous solution, in large paracrystals prepared on positively charged lipid monolayers. The increased stability of these closely packed specimens allowed us to show that both the long pitch (38 nm) and the monomer (5.8 nm) can be directly resolved by AFM in the contact mode. The right-handed helical surface, distinguishable in high resolution images, was compared with reconstructed models based on electron microscopy. The height of the rafts, a measure of the actin filament diameter, was 10 +/- 1 nm, whereas the smaller inter-filament distance, 8 +/- 1 nm, was consistent with interdigitation of the filaments. The 10 +/- 1 nm F-actin diameter is in good agreement with the results of fibre X-ray diffraction. As such specimens are relatively easy to prepare without specialized equipment, this method may allow the study of the thin filaments in which F-actin-associated proteins are also present.

[Pathogen detection in the myocardial lesion using in situ RT-PCR in mice induced by experimental CoxB(3m) virus infection]

OBJECTIVE

To detect the location of pathogens in myocardium using in situ RT-PCR technique in order to study the pathogenetic course of the myocardial lesion induced by CoxB(3m) virus infection in mice.

METHODS

(1) Thirty and fifty Balb/c mice were used respectively to establish the acute and chronic CoxB(3m) infected models, with another 25 healthy mice as the controls; (2) KS400 image analysis system (Germany) was used to measure the cardiac chamber area and the left ventricular wall thickness of the chronic infected mice and the controls; (3) CoxB(3m) virus in myocardial tissue was detected using in situ RT-PCR by direct incorporated technique which employed nucleotide labeling by anti-digoxin antibody and bonded with alkaline phosphatase (anti-dig-AKP method).

RESULTS

Picture analysis indicated that the left ventricular chamber area was enlarged and the left ventricular wall was thinner in the chronic repeated virus infected models than those of the controls. With in situ RT-PCR, positive signals for Coxsackie virus B(3m) RNA were detected not only in the myocardium of the acute Balb/c mice models but also in the myocardium of the chronic mice models.

CONCLUSION

Coxsackie virus B(3m) is able to induce pathologic lesions by exhibiting positive CVB-RNA signals in both acute and chronic models in mice. In the chronic experimental models, the cardiac chamber is enlarged while the ventricular wall is thinned which demonstrates the association with persistent infection of Coxsackie virus B(3m) virus.

[The descriptions and microscopy identification of three allied species of Dysosma versipellis]

The descriptions, histological and microscopical characteristics of three allied species of Dysosma versipellis were described.

[Mutations of APC and K-ras gene in aberrant crypt foci from human colon]

OBJECTIVE

To analyze the mutations of K-ras and APC gene in normal colorectal mucosa, aberrant crypt foci (ACF), adenoma and colorectal carcinoma (CRC); To study the genetic alteration in ACF and its possibility of being a molecular marker of very early colon cancer and to explore the relationship of ACF and colorectal adenoma.

METHODS

DNA from 35 CRC, 15 adenomas, 34 ACF and 15 cases of normal mucosa with mucous glands were isolated by micro-dissection. Direct gene sequencing of k-ras gene including codon 12, 13 and 61 as well as the mutation cluster region (MCR) of APC gene.

RESULTS

Mutation frequency of k-ras gene in ACF, adenoma and carcinoma was 17.6% (6/34), 13.3% (2/15), and 14.3% (5/35) respectively, showing no difference between the three pathologic changes. The ras gene mutation sites in adenomas, carcinomas and 4 ACF were limited to codon 12 (GGT-->GAT), but in 2 ACF, they were located in codon 13 (GGC-->GAC). K-ras gene mutation in ACF was found more frequently in old patients and in patients with polypoid cancers. No mutations were found in codon 61 in three types of tissue. Mutation rate of APC genes in adenomas and carcinomas was 22.9% (8/35) and 26.7% (4/15) respectively, which was higher than that of ACF 2.9%, (P < 0.05). APC gene mutation in carcinomas was not correlated with age, location, size and differentiation.

CONCLUSION

The morphological changes and gene mutation status are different in ACF and adenomas. ACF is a very early morphological lesion in the carcinogenesis of colorectal carcinoma. Therefore, ACF is considered to be the putative "microadenoma" where the development of colorectal carcinomas may be from "normal epithelium to ACF and then to carcinomas".

[Mössbauer spectroscopy and its application in the study of iron cation behavior in molten slags]

The principle, parameters and determination methods of Mössbauer spectroscopy are summarized. The iron cation behavior in molten slags is analyzed and Mössbauer spectra characteristics of Fe2+, Fetet3+ and Feoct3+ ions are detailed chemically and spetroscopically. The relationship between iron cation behavior and basicity, total iron, Na2O and Al2O3 addition in slags is also discussed here.