Establishment of an HBsAg mixed titer performance panel and HBsAg working standard for quality control of HBsAg diagnostic kits in Korea.

BACKGROUND: International Standards or commercial panels used for performance validation of diagnostic kits might not reflect the viral characteristics common in Korea. Also, continuous use of these materials is difficult because of limited quantity and high cost. OBJECTIVES: Establishment of HBsAg reference materials to be used as National Standards for validation of HBsAg diagnostic kits. STUDY DESIGN: 568 plasma units with OD less than 2.0 on HBsAg EIA were collected. HBsAg testing with 3 EIAs and 1 CIA was performed on all units. HBsAg positive units were subjected to HBV DNA quantification, genotyping and subtyping. Candidates for the mixed titer performance panel and working standard were confirmed for HBsAg by neutralization. A collaborative study was conducted for the candidates of the mixed titer performance panel and the working standard. RESULTS: Based on the results of the collaborative study, a working standard (KFDA08/024) consisting of a series of four-fold dilutions of 2 materials, one with genotype/subtype C2/adr and the other with C1/adw, was established. A mixed titer performance panel composed of 2 negative and 16 positive samples was also established. A G1896A and a T/I126S mutant are included in the positive samples. CONCLUSIONS: An HBsAg mixed titer performance panel and a working standard reflecting HBV genotypes/subtypes prevalent in Korea have been established as National Standards. This will enable consistent supply of validation materials, improve the validation system of HBsAg diagnostic kits in Korea and lead to quality improvement of diagnostic kits.

Euplexides A-E: Novel Farnesylhydroquinone Glycosides from the Gorgonian Euplexaura anastomosans.

Euplexides A-E (1-5), novel farnesylhydroquinone glycosides of the moritoside class, have been isolated from the gorgonian Euplexaura anastomosans. The structures of these compounds have been elucidated by combined chemical and spectral methods. The absolute stereochemistry has been determined by the modified Mosher's method and an acidic hydrolysis followed by GC analysis. These compounds exhibited moderate cytotoxicity and antioxidizing activity as well as inhibitory activity against PLA(2).