ABSTRACT
OBJECTIVE: To develop a rapid DNA detection kit for DNA extraction and PCR identification of Panax ginseng C. A. Mey. METHODS: The classical DNA extraction and PCR identification methods for Panax ginseng C. A. Mey were modified, and the compositions and reaction conditions of the kit were determined. In addition, the specificity, stability, sensitivity, and repeatability of the kit were evaluated. The genomic DNAs of genuine and counterfeit ginseng goods were extracted by the kit and PCR was performed to identify the authenticity. The purity of the extracted DNA was detected by UV spectrophotometry. Finally, commercially available ginseng samples were verified. RESULTS: The purity of the genomic DNA extracted by the kit was (1.73 ± 0.13) (OD260/OD280), and a fragment between 150 and 200 bp could be amplified only from authentic Panax ginseng C. A. Mey. The specificity of the kit was 100%. The repetitive experiments showed that the average intra-assay CV% and inter-assay CV% of the kit were 2.38% and 2. 62%, respectively. The DNA in solutions diluted by 200 times could still be detected. Stability experiment proved that repeated freeze-thawing for 20 times had no significant effect on the activity of this kit and the test sample could be stored at - 20℃ for one year. The specificity test confirmed that 8 samples among the 10 commercial products were genuine, and 2 were counterfeit. CONCLUSION: The nucleic acid extraction and purity of the DNA detection kit can meet the requirement for identification of Panax ginseng C. A. Mey. The kit has good specificity, high sensitivity, and good stability, so it is suitable for the rapid detection of Panax ginseng C. A. Mey.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the immunity level of diphtheria antibody among children living in the areas where different coverage rates of 4-vaccines stratified by results of national immunization program (NIP) reviewed in 2004.</p><p><b>METHODS</b>According to data from 4-vaccine coverage rates of NIP reviewed in 2004, 3 levels could be set. We randomly selected 2 counties at each level and then 10 villages from each county with 42 children involved who were born between 1992 and 2003. ELISA quantitative method was used to test IgG of diphtheria antitoxin.</p><p><b>RESULTS</b>(1) The positive rate of diphtheria antitoxin was only 49.6% with the highest as 78.1% and lowest as 33.0%. There was a significant decreasing trend of this positive rate with the increase of age. The highest (61.2%) fell in the group that were born in 2003 and the lowest (37.6%) was seen among children born in 1992 to 1995. (2) Geometric mean concentrations (GMCs) was only 0.48 IU/ml with a trend of decrease when age was increasing. There was no GMCs peak seen in children who were at the age of boosting, as expected. (3) Positive rates of children born between 2001 and 2003 were lower than 62% while the diphtheria-pertussis-tetanus (DPT) vaccine coverage rates were all higher than 90%. (4) There was no significant difference of diphtheria antitoxin positive rates between children with eligible routine immunization (58.1%) and those were ineligible (59.6%).</p><p><b>CONCLUSION</b>Other than some specific ones, children from most of the investigated counties had a low level of antibody against diphtheria. The coverage rate of DPT vaccine did not necessarily reflect the immunity against diphtheria, suggesting the increase of immunity against diphtheria an urgent task to be taken care of.</p>