External quality assessment on detection of hepatitis C virus RNA in clinical laboratories of China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>As with many studies carried out in European countries, a quality assurance program has been established by the National Center for Clinical Laboratories in China (NCCL). The results showed that the external quality assessment significantly improves laboratory performance for quantitative evaluation of hepatitis C virus (HCV) RNA.</p><p><b>METHODS</b>Serum panels were delivered twice annually to the clinical laboratories which performed HCV RNA detection in China. Each panel made up of 5 coded samples. All laboratories were requested to carry out the detection within the required time period and report on testing results which contained qualitative and/or quantitative test findings, reagents used and relevant information about apparatus. All the positive samples were calibrated against the first International Standard for HCV RNA in a collaborative study and the range of comparison target value (TG) designated as +/- 0.5 log.</p><p><b>RESULTS</b>The numbers of laboratories reporting on qualitative testing results for the first and second time external quality assessment were 168 and 167 in the year of 2003 and increased to 209 and 233 in 2007; the numbers of laboratories reporting on quantitative testing results were 134 and 147 in 2003 and rose to 340 and 339 in 2007. Deviation between the mean value for quantitative results at home in 2003 and the target value was above 0.5 log, which was comparatively high. By 2007, the target value was close to the national average except for the low concentrated specimens (10(3) IU/ml). The percentage of results within the range of GM +/- 0.5 log(10) varied from 8.2% to 93.5%. Some laboratories had some difficulties in the exact quantification of the lowest (3.00 log IU/ml) as well as of the highest viral levels (6.37 log IU/ml) values, very near to the limits of the dynamic range of the assays.</p><p><b>CONCLUSIONS</b>The comparison of these results with the previous study confirms that a regular participation in external quality assessment (EQA) assures the achievement of a high proficiency level in the diagnosis of HCV infection. During the 5-year external quality assessment, sensitivity and accuracy of detection in most of the clinical laboratories have been evidently improved and the quality of kits has also been substantially improved.</p>

Establishment of the first national standards for nucleic acid amplification technology assay for HBV DNA / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To establish a Chinese national standard for a nucleic acid test (NAT) for HBV DNA.</p><p><b>METHODS</b>The candidate sample of HBV DNA positive plasma was diluted with HBV-negative human plasma. The sample was lyophilised with a concentration of approximately 300,000 copies/ml. The measurement methods used included Roche Amplicor assay (version 2.0) and real-time PCR. The lyophilised preparation was calibrated by the international standard (NIBSC code: 97/746) from NIBSC.</p><p><b>RESULTS</b>The quantity of this lyophilised preparation was (1.29+/-0.24) x 10(5)IU/ml in comparison with the international standard for HBV DNA 97/746. The stability test indicated that the sample was stable at room temperature (20 to 25 degrees C) for 2 weeks and at 37 degrees C for at least 1 week. Long-term stability was observed at 2 to 8 degrees C for 6 months and at -20 degrees C for more than 2 years with no significant changes. The vial-to-vial imprecision rate was 3.53%.</p><p><b>CONCLUSION</b>Based on the results of this study, our lyophilized sample can be used as a standard in China for the nucleic acid test (NAT) for HBV DNA.</p>

Lyophilized standards for the calibration of real time PCR assay for hepatitis C virus RNA / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Since October 1997, an international standard for hepatitis C virus (HCV) nucleic acid amplification technology assay, 96/790, has been available. We compared a series of lyophilized standards with known HCV RNA concentrations against the international standard in fluorescence quantitative PCR detection.</p><p><b>METHODS</b>A series of lyophilized sera were calibrated by ROCHE COBAS AMPLICOR HCV Monitor test against the international standard and sent to various manufacturers to analyse the samples using their own kits. Then calibration curves from the series were compared with that obtained from the external standard calibration curve with the manufacture's series.</p><p><b>RESULTS</b>The standard calibration curve with the series of lyophilized serum showed an excellent correlation (R(2) > 0.98), slope and intercept that were similar to those from the manufacture's series. When the standard calibration curve from the series of lyophilized standards were used to define the values of the given sample, lower coefficients of variation between kits from different manufactures were obtained.</p><p><b>CONCLUSION</b>The results showed that the lyophilized standards could be used to setup the standard calibration curve for clinical HCV RNA quantitative PCR detection.</p>

Development of duplex TaqMan PCR assay for detection of specific gene sequence from Bacillus anthracis / 中华检验医学杂志

Objective To establish a rapid assay with high sensitivity and specificity based on the sequences for group specific gene (GS) and pathogenicity island pag A gene.Methods The PCR primers and probes were designed after the whole sequence was systemically analyzed with bio-informafion tools and blasted with Genebank database.The amplicons were inserted into plasmids so that they could be used as the standard templates to evaluate the sensitivity of the diagnostic system.This assay was based on TaqMan probes and portable Smartcycle PCR machine.Results The detection level was approximately 100 copies per reaction.There was no cross-reaction with other species of Bacillus.This assay could be completed in one hour in laboratory.Conclusion The duplex TaqMan PCR assay could be used to detect Bacillus anthracis rapidly with high sensitivity and specificity.

Reference methods and reference measurement principles in clinical biochemistry / 中华检验医学杂志

Characteristics and measurement principles of reference methods in clinical biochemistry were described.Implementation of reference systems is one of the most effective approaches to improve the accuracy and comparability of clinical laboratory test results.Reference methods are the key components of reference systems.Reference methods should have measurement uncertainties that meet the requirements of the intended use,and thus should be based on reliable measurement principles.For the well-defined biochemistry analytes,reference methods have been almost all based on instrumental analysis.Isotope dilution mass spectrometry (ID/MS) is considered most reliable and has been the major analytical principle of the reference methods.ID/MS analysis is accurate but expensive.Use of other validated instrumental analyses as reference measurement principles would be justified.

Determination of total cholesterol in serum by isotope dilution liquid chromatography tandem mass spectrometry / 中华检验医学杂志

Objective To develop a method for the determination of total cholesterol in serum by isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS).Methods Serum samples were supplemented by addition of [3,4-~(13)C_2]-cholesterol,hydrolyzed with alcoholic sodium hydroxide and oxidized into cholest-4-ene-3,6-dione by chromic acid.The oxidation products were analyzed by LC/MS/MS using atmospheric pressure chemical ionization (APCI) source and detection modes of multiple reaction monitoring (MRM) and single ion recording (SIR).Signals (peak areas) of the internal standard were corrected for the contributions of cholesterol and the signal ratios of cholesterol to internal standard for the calibrations were linearly regressed against cholesterol concentrations.The resulted regression equation was used for the calculation of serum cholesterol concentrations.Results The correlation coefficients between the peak area ratios and cholesterol concentrations were 0.999 9 and higher.Under MRM mode,the average within-run CV of the results obtained on 3 serum samples was 0.95% (ranged from 0.92% to 0.99%) and the total CVwas 0.86% (0.82% to 0.89%),and under SIR mode,the within-run CV was 0.64% (from 0.54% to 0.77%) and the total CVwas O.69% (0.62% to 0.81%),respectively. Results on certified reference materials (SRM 1951 a Level Ⅰ and Level Ⅱ;GBW 09145 and GBW 09147) showed an average bias of 0.23% (0.14% to 1.00%) under MRM mode,and 0.24% (0.07% to 1.27%) under SIR mode.Conclusions An ID-LC/MS/MS method for serum cholesterol has been developed.It is specific and precise and may be used as a candidate reference method.