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Zheng Guo

Publications and source records attributed to Zheng Guo.

32 records · Page 2Linked to original sources

[Research on pattern classification methods using gene expression data].

One of the applications of cDNA microarrays is to recognize the class and subclass of diseases such as cancers on the basis of statistical pattern classification methods using gene expression data. In this paper, we apply 2000 genes expression dataset provided by Affymatrix Company: 40 samples of intestine cancer tissue and 22 samples of normal tissue. We compare the performance of four pattern classification methods based on different feature selection methods. These pattern classification methods include: Fisher linear discriminate, Logit nonlinear discriminate, the least distance and K-nearest neighbor classifier. The results show firstly that four pattern classifiers based on the feature selection methods of t-test and classification tree all have better performance than those based on the stochastic feature selection methods, secondly that K-nearest neighbor classifier has the best performance, thirdly that both the least distance classifier and K-nearest neighbor classifier have better generalization, fourthly that four classifiers are less sensitive to the composition of samples.

Gene Expression↗

Additional bedtime H2-receptor antagonist for the control of nocturnal gastric acid breakthrough.

BACKGROUND: Nocturnal gastric acid breakthrough(NAB) is defined as intragastric pH<4 for more than one continuous hour overnight. Adding H2-receptor antagonists (H2RAs)at bedtime to high-dose proton pump inhibitors is likely to enhance nocturnal gastric pH control and decrease nocturnal gastric acid breakthrough. OBJECTIVES: To assess the effectiveness of additional bedtime H2-receptor antagonists in suppressing nocturnal gastric acid breakthrough and the incidence of adverse effects. SEARCH STRATEGY: We identified eligible trials by searching The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2003), MEDLINE (1966-July 2003), EMBASE (1980-July 2003) and CINAHL (1982-July 2003). We re-ran the search on CENTRAL (The Cochrane Library Issue 2, 2004), and in MEDLINE, EMBASE and CINAHL in June 2004. SELECTION CRITERIA: All randomized controlled trials evaluating H2-receptor antagonists for the control of nocturnal gastric acid breakthrough were eligible for inclusion. DATA COLLECTION AND ANALYSIS: We extracted data and recorded relevant information onto specially developed forms. One reviewer extracted data and a second reviewer checked data extraction. We have also double-checked data entry into RevMan. For binary outcomes, we expressed the impact of the intervention as relative risks, together with 95% confidence intervals. For scale-based outcomes, we used means and standard deviations to summarise the values in each group, provided the scale permitted sufficient values. We had intended to analyse such outcomes for the presence of skew, but the studies included were too limited to permit this. MAIN RESULTS: Two randomized crossover studies including 32 participants met the inclusion criteria. Because the design, dosage and duration of the treatment were different between the studies, it was not possible to conduct meta-analysis. There is no consistent conclusion between the two included studies in evaluating H2RAs for the control of NAB. REVIEWERS' CONCLUSIONS: We can conclude no implications for practice at this stage. Appropriately designed, large-scale randomized controlled trials with long-term follow-up are needed to determine the effects of additional bedtime H2RAs in suppressing nocturnal gastric acid breakthrough.

Drug Administration Schedule↗

[A new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique: a case report].

OBJECTIVE: To design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique and explore a method to solve the necroses of allocartilage in hemi joint allotransplantation. METHODS: Design the new custom-made artificial articular cartilage of femoral condyle. The allograft and the patient distal femurs were scanned with Picker 6000 spiral computed tomography (CT) with 1.0 slice thickness and pitch of 1.5, reconstructed the distal femurs in Voxel Q image workstation with volume rendering technique. Then downloaded the transaxial 2D image data to personal computer at 0.1 mm interval and converted it into 2D digitized contour data by using image processing software developed by our team. The 3D wire frame and solid images of femoral condyle could be reconstructed when the 2D digitized contour data were input into image processing software Surfacer 9.0 (Imageware Company, USA). Subsequently based on the clinical experience and the need of design, the 3D contour image of articular cartilage was extracted from the surrounding. Based on the extracted 3D contour image, the computer-aided design (CAD) of the custom-made artificial articular cartilage was accomplished in Surfacer software, converted the CAD model into RP data format. Standard triangularization language, imported into the LPS600 rapid prototyping machine (Hengtong Company, Xi'an Jiaotong University, China), and the resin prototype was achieved. Then the resin model was used as a positive mould to build up a silica gel negative mould, the negative mould was sent to the factory to manufacture Ti-6Al-4V alloy articular cartilage through ordinary mould-melted founding process. Finally, the whole metal cartilage was completed after melting two special cages on it. A patient was selected to clinical applying. RESULTS: A new custom-made artificial articular cartilage of femoral condyle was made. It was press-fit well to the subchondral bone of the allograft bone. The patient's one and half year follow-up result was excellent. CONCLUSIONS: We design and manufacture a new custom-made artificial articular cartilage of femoral condyle based on rapid prototyping technique. The result shows that the manufacturing process has the advantage of rapidness and precision that are very important for individualized artificial implant manufacturing. The artificial articular cartilage is press-fit well and could be a good idea to solve the necroses of allocartilage in hemijoint allotransplantation.

Adolescent↗

Learnability-based further prediction of gene functions in Gene Ontology.

Currently the functional annotations of many genes are not specific enough, limiting their further application in biology and medicine. It is necessary to push the gene functional annotations deeper in Gene Ontology (GO), or to predict further annotated genes with more specific GO terms. A framework of learnability-based further prediction of gene functions in GO is proposed in this paper. Local classifiers are constructed in local classification spaces rooted at qualified parent nodes in GO, and their classification performances are evaluated with the averaged Tanimoto index (ATI). Classification spaces with higher ATIs are selected out, and genes annotated only to the parent classes are predicted to child classes. Through learnability-based further predicting, the functional annotations of annotated genes are made more specific. Experiments on the fibroblast serum response dataset reported further functional predictions for several human genes and also gave interesting clues to the varied learnability between classes of different GO ontologies, different levels, and different numbers of child classes.

Computational Biology↗

An ensemble method for gene discovery based on DNA microarray data.

The advent of DNA microarray technology has offered the promise of casting new insights onto deciphering secrets of life by monitoring activities of thousands of genes simultaneously. Current analyses of microarray data focus on precise classification of biological types, for example, tumor versus normal tissues. A further scientific challenging task is to extract disease-relevant genes from the bewildering amounts of raw data, which is one of the most critical themes in the post-genomic era, but it is generally ignored due to lack of an efficient approach. In this paper, we present a novel ensemble method for gene extraction that can be tailored to fulfill multiple biological tasks including (i) precise classification of biological types; (ii) disease gene mining; and (iii) target-driven gene networking. We also give a numerical application for (i) and (ii) using a public microarrary data set and set aside a separate paper to address (iii).

Algorithms↗

[Analysis of codon usage in potato and its application in the modification of t-PA gene].

Bioperl-1.0 was used under Hongqi LINUX system to program the codon analysis software. According to the analysis of 98 codon DNA sequences with this software, the codon usage in potato was calculated and 4 codons have been inferred to the optimal codons. The codons of tissue plasminogen activator (t-PA) gene sequence have been reconstructed according to the results. The t-PA gene sequence containing the optimal codons of potato will be used for t-PA production by potato bioreactor.

Amino Acid Sequence↗

[Analysis of the mRNA expression similarity of genes in the same gene expression regulatory pathway].

In this work we analysed the relationship of gene expression from the point of view of gene expression regulatory pathway. Using seven sets of Saccharomyces cerevisiae gene chip expression profile data, and information from two pathway database (KEGG and CYGD), we analysed the mRNA expression similarity of genes in the same gene expression regulatory pathway by Genehub software, that involved totally 16 pathways with more than 495 genes. From the calculation of two different similarity measures-Pearson correlation coefficient and Spearman correlation coefficient, we found that about 94 percent of gene expression regulatory pathways are correlatively expressed in more than 4(including 4) sets of expression profile data, and it presents additional evidence for the correlation between gene function and its expression in the view of gene expression regulatory pathways.

Algorithms↗

Genetic linkage analysis of longitudinal hypertension phenotypes using three summary measures.

BACKGROUND: Longitudinal data often have multiple (repeated) measures recorded along a time trajectory. For example, the two cohorts from the Framingham Heart Study (GAW13 Problem 1) contain 21 and 5 repeated measures for hypertension phenotypes as well as epidemiological risk factors, respectively. Direct modelling of a large number of serially and biologically correlated traits in the context of linkage analysis can be prohibitively complex. Alternatively, we may consider using univariate transformation for linkage analysis of longitudinal repeated measures. RESULTS: We evaluated the utility of three conventional summary measures (mean, slope, and principal components) for genetic linkage analysis of longitudinal phenotypes by analyzing the chromosome 10 data of the Framingham Heart Study. Except for the temporal slope, all of the summary methods and the multivariate analysis identified the previously reported region, marker GATA64A09, for systolic blood pressure or high blood pressure. Further analysis revealed that this region may harbor gene(s) affecting human blood pressure at multiple stages of life. CONCLUSION: We conclude that mean and principal components are feasible alternatives for genetic linkage analysis of longitudinal phenotypes, but the slope might have a separate genetic basis from that of the original longitudinal phenotypes.

Adult Children↗

Multivariate sib-pair linkage analysis of longitudinal phenotypes by three step-wise analysis approaches.

BACKGROUND: Current statistical methods for sib-pair linkage analysis of complex diseases include linear models, generalized linear models, and novel data mining techniques. The purpose of this study was to further investigate the utility and properties of a novel pattern recognition technique (step-wise discriminant analysis) using the chromosome 10 linkage data from the Framingham Heart Study and by comparing it with step-wise logistic regression and linear regression. RESULTS: The three step-wise approaches were compared in terms of statistical significance and gene localization. Step-wise discriminant linkage analysis approach performed best; next was step-wise logistic regression; and step-wise linear regression was the least efficient because it ignored the categorical nature of disease phenotypes. Nevertheless, all three methods successfully identified the previously reported chromosomal region linked to human hypertension, marker GATA64A09. We also explored the possibility of using the discriminant analysis to detect gene x gene and gene x environment interactions. There was evidence to suggest the existence of gene x environment interactions between markers GATA64A09 or GATA115E01 and hypertension treatment and gene x gene interactions between markers GATA64A09 and GATA115E01. Finally, we answered the theoretical question "Is a trichotomous phenotype more efficient than a binary?" Unlike logistic regression, discriminant sib-pair linkage analysis might have more power to detect linkage to a binary phenotype than a trichotomous one. CONCLUSION: We confirmed our previous speculation that step-wise discriminant analysis is useful for genetic mapping of complex diseases. This analysis also supported the possibility of the pattern recognition technique for investigating gene x gene or gene x environment interactions.

Adult Children↗

[Expression of basic fibroblast growth factor and fibronectin in tissue engineering skin allograft during healing process].

OBJECTIVE: The aim of this study was to explore the expression of basic fibroblast growth factor (bFGF) and fibronectin during the healing process of allograft tissue engineering skin. METHODS: The tissue engineering skin that was obtained from neonatal SD rats was cultured in the lab. Afterwards, the skin was grafted into adult SD rats, and the expressions of bFGF and fibronectin were detected on the 7th, 10th, 14th, 20th and 30th day after the allograft of the tissue engineering skin. The autografted skin in 15 adult Wistar rats and the normal skin in 15 Wistar were treated as the control. HE staining and immunohistochemical staining were used to examine the healing of grafted skin. RESULTS: The expression of bFGF and fibronectin was the strongest on the 10th day after graft, and was weaker before the 10th day and after the 14th day. The expression changes of bFGF and fibronectin were similar as they were in the autograft group. CONCLUSION: The expression changes of bFGF and fibronectin in the tissue engineering skin during the process of wound healing were similar to those of autografted skin, and these can promote the repair of tissue engineering skin allograft.

Animals↗

[Preliminary analysis on the gene expression profiles of different types of gliomas with cDNA array].

BACKGROUND & OBJECTIVE: There is great signification to classify the molecular pathogenesis of gliomas. Gene chip is able to profile the gene expression of tumors, which may become a new method for studying molecular pathology of tumors. The cDNA was used in order to detect the differences in gene expression profiles of different types of gliomas. METHODS: cDNA probes tagged with 32P were converted from total RNA extracted from 4 samples of 3 different pathological types, including oligodendrogliomas, anaplastic astrocytomas and ependymomas, and one sample of normal human brain tissue as well, which were then hybridized to the Atlas array. After autoradiography, the gene expression profiles were analyzed with the special software and by the cluster analysis. RESULTS: As compared to the normal brain tissue, the number of differential expressed genes in these tumor samples ranging from 11 to 118 was found. These 4 samples could be divided into 3 kinds of types when 107 differential expressed genes were selected to be as the cluster analysis index. This result was in accordance with the neuropathological diagnosis. CONCLUSION: cDNA array is able to profile gene expression in different types of gliomas. Combined with the bioinformational method, we may further obtain useful information about molecular pathology of gliomas.

Gene Expression Profiling↗

Solvent-free enzymatic synthesis of 1,3-diconjugated linoleoyl glycerol optimized by response surface methodology.

An operation mode with N(2) bubbling under vacuum was employed for the solvent-free synthesis of 1,3-diconjugated linoleoyl glycerol (1,3-dCLG) from conjugated linoleic acid (CLA) catalyzed by Novozym 435. The response surface methodology (RSM) was adopted for the optimization of the reaction conditions with five major factors (incubation time, temperature, enzyme load, substrate mole ratio, and system vacuum) and three responses (CLA conversion, 1,3-dCLG yield, and acyl migration). Two sets of optimal conditions were recommended. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of 1,3-dCLG yield. Under the optimal conditions, the yield of 1,3-dCLG up to 93% was obtained. The reaction was scaled up to a production level of 100 g of 1,3-dCLG at a yield of 90.7%, indicating a promising feature of the technology in industrial applications.

Algorithms↗

Characteristics of immobilized lipase on hydrophobic superparamagnetic microspheres to catalyze esterification.

A novel immobilized lipase (from Candida rugosa) on hydrophobic and superparamagnetic microspheres was prepared and used as a biocatalyst to catalyze esterification reactions in diverse solvents and reaction systems. The results showed that the immobilized lipase had over 2-fold higher activities in higher log P value solvents. An exponential increase of lipase activity against log P of two miscible solvent mixtures was observed for the first time. Both free and immobilized lipase achieved its maximum activity at the range of water activity (a(w)) 0.5-0.8 or higher. At a(w) 0.6, the immobilized lipase exhibited markedly higher activities in heptane and a solvent-free system than did the native lipase. In multicompetitive reactions, the alcohol specificity of the lipase showed a strong chain-length dependency, and the immobilized enzyme exhibited more preference for a longer-chain alcohol, which is different from previous reports. The immobilized lipase showed higher specificities for butyric acid and the medium-chain-length fatty acids (C(8)-C(12)). Then, the immobilized lipase was extended to solvent-free synthesis of glycerides from glycerol and fatty acids. Recovered by magnetic separation, the immobilized lipase exhibited good reusability in repeated batch reaction, indicating its promising feature for biotechnology application.

Adsorption↗

Peeling off the hidden genetic heterogeneities of cancers based on disease-relevant functional modules.

Discovering molecular heterogeneities in phenotypically defined disease is of critical importance both for understanding pathogenic mechanisms of complex diseases and for finding efficient treatments. Recently, it has been recognized that cellular phenotypes are determined by the concerted actions of many functionally related genes in modular fashions. The underlying modular mechanisms should help the understanding of hidden genetic heterogeneities of complex diseases. We defined a putative disease module to be the functional gene groups in terms of both biological process and cellular localization, which are significantly enriched with genes highly variably expressed across the disease samples. As a validation, we used two large cancer datasets to evaluate the ability of the modules for correctly partitioning samples. Then, we sought the subtypes of complex diffuse large B-cell lymphoma (DLBCL) using a public dataset. Finally, the clinical significance of the identified subtypes was verified by survival analysis. In two validation datasets, we achieved highly accurate partitions that best fit the clinical cancer phenotypes. Then, for the notoriously heterogeneous DLBCL, we demonstrated that two partitioned subtypes using an identified module ("cellular response to stress") had very different 5-year overall rates (65% vs. 14%) and were highly significantly (P < 0.007) correlated with the clinical survival rate. Finally, we built a multivariate Cox proportional-hazard prediction model that included 4 genes as risk predictors for survival over DLBCL. The proposed modular approach is a promising computational strategy for peeling off genetic heterogeneities and understanding the modular mechanisms of human diseases such as cancers.

Databases, Genetic↗