Application of a support vector regression on prediction of bacillary dysentery combined with meteorological and air pollutants index / 中华疾病控制杂志

Objective To explore the application of support vector regression (SVR) model combined with meteorological and air pollutants index in the prediction of the cases of bacillary dysentery in Lanzhou City, so as to provide scientific reference for the prevention and control of bacillary dysentery.Methods Time series data of the reported cases of bacillary dysentery from December 2013 to August 2016, combined with the meteorological and air pollutants data, were used as training set to fit support vector regression model. The data from September 2016 to December 2017 was used as validation set to verify the model and compare the effect in fit and prediction with different models. Results A total of 7 192 bacillary dysentery cases were reported in Lanzhou City from 2013 to 2017. The correlation coefficient of meteorological and pollution factors with the cases of bacillary dysentery was more than 0.4, except air pressure. The parameters of the fit model were selected based on the integrated data, acquiring the three parameters with the smallest test error were C=5, γ=0.02 and ε=0.000 1, respectively. The validation set was used to test the different models, which showed that the integrated data model had the best predictive accuracy and robustness . The root mean squared error (RMSE) was 0.164 7 and the mean absolute percentage error (MAPE) was 16.405%. Conclusion SVR model combined with meteorological and air pollutants index is effective in the prediction of bacterial dysentery.

Optimization and assessment of a reverse hybridization system for the detection of HBV drug-resistant mutations / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To establish a detection method for HBV drug-resistant mutations related to lamivudine, adefovir and entecavir by optimization and assessment of reverse hybridization system.</p><p><b>METHOD</b>26 degenerated probes covering 10 drug-resistant hotspots of 3 drugs were synthesized and immobilized on the same positively charged nylon membrane. PCR products labeled with digoxigenin were hybridized with corresponding probes. To improve the sensitivity and specificity, 4 reaction steps of reverse hybridization were optimized including the number of labeled digoxigenin, the energy intensity of UV cross-linking, hybridization and stringency wash conditions. To prove the feasibility, the specificity, sensitivity and accuracy of this system were assessed respectively.</p><p><b>RESULT</b>Sensitive and specific results are obtained by the optimization of the following 4 reaction steps: the primers labeled with 3 digoxigenin, energy intensity of UV cross-linking for 1500 x 0.1 mJ/cm², hybridization at 42 degrees C and stringency wash with 0.5 x SSC and 0.1% SDS solution at 44 degrees C for 30 min. In the assessment of system, the majority of probes have high specificity. The quantity of PCR product with a concentration of 10 ng/μl or above can be detected by this method. The concordant rate between reverse hybridization and direct sequencing is 93.9% in the clinical sample test.</p><p><b>CONCLUSION</b>Though the specificity of several probes needs to be improved further, it is a simple, rapid and sensitive method which can detect HBV resistant mutations related to lamivudine, adefovir and entecavir simultaneously. Due to the short distance between 180 and 181, likewise 202 and 204, the sequence of the same probe covers two codon positions, and hybridization will be interfered by each other. To avoid such interference, the possible solution is that probes are designed by arranging and combining various forms of two near codons.</p>

Detection of HBV resistant mutations related to lamivudine, adefovir and entecavir by reverse hybridization technique / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To establish a method for simultaneous detection of HBV resistant mutations associated with three kinds of nucleoside analogues.</p><p><b>METHODS</b>According to 981 HBV complete sequences in GenBank, two pairs of conserved primers labeled with digoxigenin were synthesized to amplify the region of HBV reverse transcriptase. To detect non-synonymous amino acid substitutions associated with lamivudine, adefovir and entecavir, 26 specific oligonucleotide probes covering ten different codon positions, I169T, V173L/G, L180M, A181T/V, T184G, S202I/G, M204V/I, Q215S, N236T and M250V/I/L were synthesized and immobilized on nylon membranes charged positively. The oligonucleotide probes immobilized on nylon membranes were then hybridized with PCR products labeled with digoxigenin to detect three drug-resistant mutations. In order to observe specificity and accuracy of probes, HBV wild-type, resistant reference strains and patients serums were assayed by reverse hybridization technique, respectively.</p><p><b>RESULTS</b>The specific probes of 10 codon positions related to HBV wild-type and resistant reference strains, including I169T, V173L, L180M, A181T, T184G, S202I, M204V, Q215S, N236T, M250V, were distinguished effectively by reverse hybridization method. The results results of 37 samples applicated the method were in accordance with that Of DNA sequencing.</p><p><b>CONCLUSION</b>Reverse hybridization technique can be applied to detect HBV resistant mutations associated with Lamivudine, Adefovir and Entecavir rapidly and accurately.</p>

Development of a Reverse Dot Blot System for Rapid Detection of HBV Genotypes / 中国生物工程杂志

To develop a reverse dot blot assay for rapid detection of HBV genotypes.Specific oligonucleotides probes were desighed and immobilized on nylon membranes.The DNA sample to be tested was PCR-amplified with DIG labeling primers and then hybridized with the immobilized probes.This procedure for detecting HBV genotypes was simple,rapid and specificity.30 specimens in Chongqing area were collected and detected by this method,and results were evaluated using direct sequencing.Results showed that: This new method was applicable to precise detection HBV genotypes for specimen with copies up to 103,and the HBV genotyping results showed that genotype B was the predominant genotype in Chongqing area.