title: Assessment of the quality of frozen serum by spectrophotometric analysis and sperm bioassay.
abstract: Serum is an integral part of media used for in vitro fertilization (IVF) and andrology work. Previous studies showed that the IVF results could benefit if sera were screened for deleterious effects before use. Such screening is impractical when fresh sera are used but may be feasible if the serum is frozen prior to use. This study assessed the impact of freezing on the quality of serum. A total of 158 serum samples, prepared in a university-based andrology-IVF center, were included in the study. The frozen sera were thawed in batches to be used in a series of laboratory experiments. Serum quality was evaluated by spectrophotometric analysis and sperm bioassay under several defined conditions: fresh, frozen, pre- and postfiltration, pre- and postcentrifugation, and the patients' fertility condition. Although all sera were filtered through 0.22-micron filter, more than 10% frozen sera required 0.4- or a combination of 0.8- and 0.4-micron filters before they could be passed through the 0.22-micron filter. Frozen sera that were directly filtrable with a 0.22-micron filter lost 13% turbidity upon filtration. The turbidity of the frozen sera were higher compared to fresh ones as revealed by optical density (OD) and relative light scattering (RLS) spectrophotometry. The freeze/storage-induced spectrophotometric changes did not correlate with the storage time. The centrifugation caused precipitation of sera components. The rate of precipitation of the serum components correlated with the duration of freezing. Spectrophotometric analysis and sperm bioassay did not differentiate the sera of pregnancy-positive and pregnancy-negative subjects. The sperm bioassay failed to detect any biological impact of freezing-induced spectrophotometric changes in the sera, suggesting that the freezing-induced changes did not significantly diminish the serum's capability of supplementing the culture media.
authors.affiliation: Department of Obstetrics and Gynecology, University of South Alabama, Mobile 36688, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Hossain
authors.forename: S
authors.initials: S
authors.lastname: Barik
authors.forename: B
authors.initials: B
authors.lastname: Rizk
authors.forename: I H
authors.initials: IH
authors.lastname: Thorneycroft
mesh_terms: D001769:Blood; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D005307:Fertilization in Vitro; D005615:Freezing; D006801:Humans; D008297:Male; D009391:Nephelometry and Turbidimetry; D011247:Pregnancy; D013053:Spectrophotometry; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D003470:Culture Media