Volume regulatory function and sperm membrane dynamics as parameters for evaluating cryoprotective efficiency of a freezing extender.

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.

Functional significance of the cell volume for detecting sperm membrane changes and predicting freezability in dog semen.

Due to the similarity of plasma membrane changes induced by capacitation and cryopreservation, the parameters describing sperm response to capacitating conditions can be used for evaluating the cryopreservation response in many animal systems. In dog sperm, the response of the total sperm population to ionophore treatment has been shown to be an indication of the freezability of semen samples. Another sperm functional characteristic decisive for cryopreservability is cell volume regulation, due to the generation of essential osmotic gradients across the plasma membrane during the freeze-thaw cycles.

Concordance of three measures of cocaine use in an arrestee population: hair, urine, and self-report.

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.