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BACKGROUND: To verify and evaluate the performance characteristics of a creatine kinase phosphokinase isoenzymes MB (CK-MB) assay kit, which produced by Xiamen Innodx Biotech Co. Ltd. METHODS: Evaluation was carried out according to "Guidelines for principle of analysis performance evaluation of in vitro diagnostic reagent." The performance parameters included detection limit, linearity range, reportable range, recovery test, precision verification, interference test, cross-reactivity, matrix effect, and method comparison. RESULTS: The detection limit was 0.1 ng/mL. The assay had clinical linearity over range of 0.1 ng/mL-500 ng/mL. Reportable range was from 0.1 ng/mL to 1000 ng/mL. The average percent of recovery was 99.66%. The coefficient of variation (CV) for within-run and between-run of low CK-MB sample was 5.55% and 6.16%, respectively. As for high-level sample, it was 7.88% and 7.80%. In medical decision level, the relative deviation (Bias) of all interference tests was lower than 15%. When the sample had mild-hemolysis; hemoglobin ≤15 g/L; triglyceride ≤17 mmol/L; bilirubin ≤427.5 µmol/L; rheumatoid factor ≤206U/mL, there was no significant interference to be found. Moreover, assay kit had no cross-reaction with CK-MM and CK-BB. At last, total diagnostic accuracy of kit was 93.24%, when compared with refer kit. CONCLUSION: Overall the results of the verification study indicated the performance of kit is met the requirements of the clinical test.

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BACKGROUND: Tumor marker carbohydrate antigen 15-3 (CA15-3) is used as a biomarker to aid to diagnose and monitor the prognosis of breast cancer patients. A new quantitative determination kit for CA15-3 with chemiluminescent assay was developed by Xiamen InnoDx Biotech Co., Ltd, China. Therefore, we conducted the report to evaluate the performance of the kit. METHODS: According to the "Guiding principles on performance analysis of diagnostic reagents in vitro", the calibration curve, limit of detection, reportable range, accuracy, precision, anti-interference capability, cross-reaction and comparison by measuring EDTA plasma and serum were carried out. In addition, the kit was performed in parallel to electrochemiluminescence immunoassay kit (Roche) to analyze the correlation between the two kits. RESULTS: Regression equation of calibration curve of the kit was Y=0.7914X+4.1032 (R2 =.990). Limit of detection was 0.0347 U/mL. The reportable range was 0.5-2400 U/mL. Recovery ratio was 100.0%-104.8%. Coefficient of variations (CVs) of within-run and between-run were 4.8%-7.6% and 5.8%-7.4% respectively. No remarkable interferences (all Bias% were less than ±10%) were detected when samples contained hemoglobin ≤183.8 µmol/L, bilirubin ≤340 µmol/L, triglyceride ≤18.1 mmol/L, or rheumatoid factor ≤400 U/mL. No cross-reaction was present in the kit. Moreover, compared with the results from electrochemiluminescence immunoassay kit (Roche) in 345 serum samples, there was a satisfied correlation coefficient of 0.977 (P<.01), and the kit was simultaneously fit for the detection of EDTA plasma and serum samples. CONCLUSION: The new kit validated satisfactorily, and it can be used for detecting CA15-3 in clinical practice.

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Two colloidal gold immunochromatographic assays (CGIAs) for detection of EV71- and CA16- immunoglobulin M (IgM) were developed and evaluated. A total of 1465 sera collected from children with hand, foot, and mouth disease (HFMD), non-HFMD patients and healthy children. The sensitivity of IgM CGIA tests for EV71 and CA16 were 97.6% (330/338) and 91.6% (296/323) respectively, compared to those who were viral RNA positive by PCR. Their performances were comparable to those of commercial ELISA kits, with agreement of 98.1% for EV71-IgM and 97.3% for CA16-IgM. In addition, for EV71- and CA16-IgM CGIAs, the results of whole blood samples were 99.6% (248/249) and 100% (191/191) concordant to those with serum samples, respectively. As rapid point-of-care (POC) tests, the two CGIAs were suitable to be used in community clinic units, especially in resource-poor areas and will facilitate the control of HFMD.

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The recent and continuing epidemic of enterovirus 71 in China has affected millions of children and resulted in thousands of deaths. Timely diagnosis and management is essential for disease control. Current enterovirus 71 molecular tests require resources that are unavailable for on-site testing. We have developed a simple-to-operate nucleic acid test, the convenient and integrated nucleic acid test, for local medical institutions. It uses a convective PCR for rapid amplification, a dipstick for visual detection of PCR products, and a simple commercial kit for nucleic acid extraction. By using a specially designed reagent and reaction tube containing a dipstick, the amplification and detection processes are well integrated and simplified. Moreover, cross contamination that may be caused by an open-tube detection system can be avoided. On the basis of the convenient and integrated nucleic acid test, an enterovirus 71 assay for on-site testing was developed. After evaluating known hand, foot, and mouth disease virus stocks of 17 strains of 11 different serotypes, this assay showed a favorable detection spectrum and no cross-reactivity. Its clinical performance was established by testing 141 clinical samples and comparing the results with a nested RT-PCR method. The assay showed a clinical sensitivity and specificity of 98.5% and 100%, respectively. Our results suggest that this convenient and integrated nucleic acid test enterovirus 71 assay may serve as an on-site diagnosis tool.

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Diagnosis of Coxsackievirus A16 (CA16) infection in China relies mainly on reverse transcription-polymerase chain reaction (RT-PCR) that require expensive equipment and special trained personnel, thus making its wide application in health care settings unlikely. In this study, a novel IgM anti-CA16 assay was developed for the detection of IgM antibodies to CA16 in serum. The responses and diagnostic value of IgM for the CA16 infection were assessed by testing 1970 serum samples. The results showed that sensitivity of IgM test was 84.6% (259/306, 95% CI: 80.1-88.5), and specificity in control subjects and patients with CA16 HFMD was 99.2% (1508/1520, 95% CI: 98.6-99.6) and 90.3% (14/144, 95% CI: 84.2-94.6), respectively. The IgM positive rate reached 56.3% in the sera collected within the first day after onset, increased continuously to 95.3% at day 5 to day 7 after onset, and then reached 100% after more than 8 days. The cross-reaction rate in patients infected with other non-CA16 enteroviruses was 9.7% (14/144). These results suggest that the IgM anti-CA16 assay offers a rapid, convenient, and reliable method to detect acute CA16 infections.

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Enterovirus 71 (EV71) infection is more likely to induce severe complications and mortality than other enteroviruses. Methods for detection of IgM antibody against EV71 had been established for years, however, the performance of the methods in the very early diagnosis of EV71 infection had not been fully evaluated, which is especially meaningful because of the short incubation period of EV71 infection. In this report, the performance of an IgM anti-EV71 assay was evaluated using acute sera collected from 165 EV71 infected patients, 165 patients infected with other enteroviruses, and more than 2,000 sera from healthy children or children with other infected diseases. The results showed a 90% sensitivity in 20 patients who were in their first illness day, and similar sensitivity remained till 4 days after onset. After then the sensitivity increased to 95% to 100% for more than one month. The specificity of the assay in non-HFMD children is 99.1% (95% CI: 98.6-99.4), similar as the 99.9% specificity in healthy adults. The cross-reaction rate in patients infected with other non-EV71 enteroviruses was 11.4%. In conclusion, the data here presented show that the detection of IgM anti-EV71 by ELISA affords a reliable, convenient, and prompt diagnosis of EV71 infection.

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A new rapid diagnostic test for detection of influenza A virus was evaluated with four sets of experiments: first, a comparison with a commercial diagnostic kit against a panel of virus strains was conducted; second, the kit was tested against a collection of 40 strains of influenza A virus isolated from five different host species and 26 strains of other respiratory viruses used as controls; third, the kit was tested against specimens collected in the field obtained from human and chicken; and fourth, the kit was tested against the novel pandemic influenza A/H1N1 2009 clinical specimens obtained from admitted to hospital patients. The test kit displayed a sensitivity of 88% for both human specimens and avian specimens. The corresponding specificity was 99.3% for human specimens and 96.5% for avian specimens. This test kit may be useful for rapid diagnosis of influenza A virus.

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The performance of H5 Dot ELISA, a rapid test for detection of avian H5N1 influenza virus, was evaluated using 30 H5N1 strains belonging to 10 major genetic groups of H5N1 influenza virus, 14 strains of non-H5N1 influenza virus and 652 field samples collected from healthy and diseased chickens from markets and poultry farms. The detection limit of the test for all 30 strains of H5N1 virus was < or = 0.1 hemagglutinin (HA) units and the test yielded a negative result when tested against 100 HA units of the non-H5N1 viruses. The test gave a positive result for 87 of the 106 poultry samples from which H5N1 virus was isolated by culture and 3 of 546 culture-negative poultry samples. Compared with virus culture, the overall prediction rate of the test was determined to be 96.6%; the positive prediction rate was 96.7% and negative prediction rate, 96.6%. The false positive rate was 0.5% and false negative rate 17.9%. Considering that the test is also convenient to use, it was concluded that H5 Dot ELISA is suitable for field use in the investigation of H5N1 influenza outbreaks and surveillance in poultry.

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Spherical, smooth-surfaced and mechanically stable alginate-poly(L-histidine) (PLHis) microcapsules with narrow particle size distributions were prepared by incubating calcium alginate beads in aqueous solutions of PLHis. The in vitro release characteristics, drug loading and encapsulation efficiency of the microcapsules were investigated using bovine erythrocytes hemoglobin (Hb) as a model drug. The results showed that the concentration of Ca(2+) ions had a considerable effect on the drug loading, encapsulation efficiency and in vitro release behavior of the microcapsules. When the concentration of CaCl(2) in the PLHis solution was increased from 0 to 3.0% (w/v), the drug loading and encapsulation efficiency decreased significantly from 38.0 to 4.3% and from 92.9 to 8.0%, respectively, while the total cumulative release of Hb from microcapsules in phosphate buffered saline solution (PBS, pH 6.8) decreased from 96.2 to 72.8% in 24 h. No significant protein release was observed during 70 h of incubation in hydrochloric acid solution (pH 1.2). However, under neutral conditions (PBS, pH 6.8), the Hb was completely and stably released within 24-70 h. An explosion test showed that the stability of alginate-PLHis microcapsules depended strongly on the concentration of PLHis and the calcium ions in solution. [Diagram: see text] Microscopy photo of Hb-loaded alginate-PLHis microcapsules.

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