ABSTRACT
In the past years a series of functional assays has been developed to determine the structural, morphological and functional integrity of the plasma membrane and sperm acrosomal membrane. Cell volume regulation is an important physiological function crucial for the success of cryopreservation. In this study, the effects induced by freezing-thawing were judged by evaluating the functional characteristics of frozen-thawed semen samples submitted to secondary stress such as osmotic challenge or incubation under capacitating conditions, following cryopreservation. Prior to freezing, dog semen samples were diluted in the presence or absence of Equex STM Paste, which contains sodium dodecyl sulphate (SDS) as the active ingredient. Cell volume regulation and capacitation and calcium ionophore-induced membrane dynamics were assessed in freshly diluted and frozen-thawed semen samples by electronic volume measurement and flow cytometry. Cryopreservation led to a disturbance of the volume regulatory function and to a rapid decrease in the proportion of acrosome-reacted live spermaotozoa. Extender containing Equex STM Paste had a protective effect on isotonic cell volume, on regulatory function under hypertonic conditions, and on the proportion of live acrosome-reacted cells. The evaluation of the functional state of sperm submitted to secondary stress after freezing-thawing leads to a more subtle characterization of sperm function and helps improve the cryoprotective efficiency of the extender.
Subject(s)
Cell Membrane/physiology , Cryopreservation/veterinary , Cryoprotective Agents , Dogs , Semen Preservation/veterinary , Spermatozoa/ultrastructure , Acrosome/physiology , Acrosome/ultrastructure , Acrosome Reaction , Animals , Cell Membrane/ultrastructure , Cell Size , Cryopreservation/methods , Ionophores/pharmacology , Male , Semen Preservation/methods , Sperm Capacitation , Sperm MotilityABSTRACT
This article reports on the comparison of self-reported cocaine use with urinalysis outcomes and radioimmunoassay of hair samples for cocaine. The data is based on a voluntary sample of approximately 300 arrestees, tested and interviewed anonymously. The study reports high rates of request compliance for both urine and hair samples, and affirms a relatively high degree of underreporting of cocaine use. Radioimmunoassay of hair appears to detect considerably larger degrees of cocaine use than are detected by urinalysis. The differential rates of detection between hair and urine are less dramatic in subjects who appear to be high rate users.
