title: Preliminary investigations on the standardisation and quality control for the determination of gamma-glutamyltranspeptidase activity in seminal plasma.
abstract: The present study was designed to assess the effects of centrifugation velocity, standing time after dilution, freezing-thawing and chymotrypsin on the determination of gamma-glutamyltranspeptidase (gamma-GT) activities in seminal plasma, and to establish an instruction for the standardisation and quality control for the determination of gamma-GT within the same laboratory and among different laboratories. The gamma-GT level and sperm concentration of each of 72 samples of seminal plasma obtained by centrifugation at 1000 g for 10 min or 3000 g for 15 min were assayed. In addition, gamma-GT activities in diluted seminal plasma with different standing time and in samples with or without chymotrypsin were measured. The results showed that there was a significant difference of gamma-GT levels in seminal plasma obtained by centrifugation at different velocities (P < 0.001), and that gamma-GT activities in seminal plasma measured after standing for 30 min after dilution were notably lower than those measured immediately after dilution (P < 0.001). However, the data indicated that both chymotrypsin and freezing-thawing had no apparent effect on the determination of seminal gamma-GT. In conclusion, standing time after dilution and centrifugation velocity should be standardised, and frozen seminal plasma could serve as quality control products for the determination of gamma-GT activity among different laboratories.
authors.affiliation: Department of Reproduction & Genetics, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China.
authors.forename: F
authors.initials: F
authors.lastname: Chen
authors.forename: J-C
authors.initials: JC
authors.lastname: Lu
authors.forename: H R
authors.initials: HR
authors.lastname: Xu
authors.forename: Y-F
authors.initials: YF
authors.lastname: Huang
authors.forename: N-Q
authors.initials: NQ
authors.lastname: Lu
mesh_terms: D002498:Centrifugation; D002918:Chymotrypsin / Q000378:metabolism; D015925:Cryopreservation / Q000592:standards; D006801:Humans; D008297:Male; D011786:Quality Control; D012661:Semen / Q000201:enzymology*; D013048:Specimen Handling / Q000592:standards*; D013053:Spectrophotometry; D005723:gamma-Glutamyltransferase / Q000032:analysis* / Q000592:standards
chemical_list: D005723:gamma-Glutamyltransferase; D002918:Chymotrypsin