Minimally processed fresh frozen human reference sera: preparation, testing, and application to international external quality assurance

The preparation of unmodified or minimally processed fresh frozen human sera is described, as well as the previous use of such sera, e.g. in Nordic and international external quality assurance (EQA) activities. The unmodified serum is prepared from fresh donors' blood collected in dry bags and allowed to coagulate. The serum is collected "on the clot", pooled, filtered, mixed, dispensed in polypropylene vials and frozen at -80 degrees C without further processing. Some batches were slightly modified by spiking or dilution. Critical steps of the production and use of the sera are described and improvements are discussed. A total of 34 different batches have been prepared since 1985. Results from homogeneity and stability studies are presented. The studies cover 18 routine components in serum stored at +4 degrees C to 37 degrees C for up to 34 days. Good stability was observed for storage of all components, with the exception of triglyceride. Amylase, creatininium, glucose, gamma-glutamyltransferase, urate (and perhaps carbamide) showed deterioration after 13 days of incubation at 37 degrees C. The long-term stability at -80 degrees C is reviewed and new data are presented, e.g. as consensus values from EQA schemes, where the same serum has been sent out three times over 5 years, and from reference measurement procedure values that have been assigned twice with an interval of 5 years. Furthermore, a 10-year stability study has been started.

Sister chromatid exchanges and structural chromosome aberrations in lymphocytes in operating room personnel

Information on possible chromosomal damage in humans after long-term exposure to trace concentrations of waste anaesthetic gases is scarce. We examined peripheral lymphocytes in operating room personnel for both chromosome aberrations and sister chromatid exchanges (SCE). Following a standardized procedure of cultivation and staining, 30 cells from each person were scored for SCE and 100 cells from each person were examined for chromosome aberrations. A total of 45 persons were examined, representing anaesthetists (n = 15), operating room nurses assisting the surgeon (n = 10), nurses circulating in the operating room (n = 8) and healthy, unexposed controls (n = 12). The median duration of working in the operating room was 102 months, 66 months and 66 months, respectively. Time-weighted concentration levels of 2.5-4.3 p.p.m. of halothane and 25-400 p.p.m. of nitrous oxide were measured in the breathing zones of the anaesthetists during mask anaesthesia. Examination of SCE and chromosome aberrations yielded corresponding qualitative results. With both tests, no statistically significant difference was observed between the four groups of persons. It was concluded that by examination of both SCE and chromosome aberrations in peripheral lymphocytes in operating room personnel, no indication was found of a mutagenic effect of long-term exposure to trace concentrations of waste anaesthetic gases.