New Insight into Sperm Capacitation: A Novel Mechanism of 17ß-Estradiol Signalling.

17ß-estradiol (estradiol) is a natural estrogen regulating reproduction including sperm and egg development, sperm maturation-called capacitation-and sperm⁻egg communication. High doses can increase germ cell apoptosis and decrease sperm count. Our aim was to answer the biological relevance of estradiol in sperm capacitation and its effect on motility and acrosome reaction to quantify its interaction with estrogen receptors and propose a model of estradiol action during capacitation using kinetic analysis. Estradiol increased protein tyrosine phosphorylation, elevated rate of spontaneous acrosome reaction, and altered motility parameters measured Hamilton-Thorne Computer Assisted Semen Analyzer (CASA) in capacitating sperm. To monitor time and concentration dependent binding dynamics of extracellular estradiol, high-performance liquid chromatography with tandem mass spectrometry was used to measure sperm response and data was subjected to kinetic analysis. The kinetic model of estradiol action during sperm maturation shows that estradiol adsorption onto a plasma membrane surface is controlled by Langmuir isotherm. After, when estradiol passes into the cytoplasm, it forms an unstable adduct with cytoplasmic receptors, which display a signalling autocatalytic pattern. This autocatalytic reaction suggests crosstalk between receptor and non-receptor pathways utilized by sperm prior to fertilization.

Kinetic analysis of decreased sperm fertilizing ability by fluorides and fluoroaluminates: a tool for analyzing the effect of environmental substances on biological events.

Fluorides and fluoroaluminates decrease mouse sperm fertilizing potential by modifying the process of sperm preparation for fertilization, so-called capacitation, followed by acrosome reaction (AR). Capacitation was monitored by protein tyrosine phosphorylation (pTyr), and AR was induced consequently. The aim of this study was to apply kinetic analysis to the previously obtained dependences of pTyr and AR at capacitation times, and propose a mathematical theory for a mechanism when sperm maturation ability is amended by external stimuli. The experimental input data, previously obtained, are consistent with the proposed theory and the results of kinetic analysis show that sperm capacitation runs as two subsequent first-order steps. Firstly, an unstable intermediate is formed and then gradually decomposes. The time corresponding to the maximal production of the unstable intermediate is probably most suitable for sperm obtaining the ability to fertilize the egg. The presented calculations indicate that the application of kinetic analysis can serve as a tool to predict or confirm a course of biological events that are modified by external factors, and therefore the proposed theory shall be of interest to a broad scientific audience.

Analysis of estrogens and estrogen mimics in edible matrices--a review.

This review provides a brief survey of the biological effects of selected endocrine-disrupting compounds that are formed after internal exposure of organisms. Further, the present analytical methods available for the determination of these compounds in foodstuffs are critically evaluated. The attention is primarily devoted to the methods for sample pretreatment, which are the main source of errors and are usually the most time-consuming step of the whole analysis. This review is focused on selected natural and synthetic estrogens, estrogen conjugates, and chemical additives used in the plastic industry that can act as estrogen mimics.

Fundamental study of enantioselective HPLC separation of tapentadol enantiomers using cellulose-based chiral stationary phase in normal phase mode.

A sensitive and specific high performance liquid chromatography method for the separation and determination of tapentadol enantiomers has been developed and validated. Ten different chiral columns were tested in a normal phase system. Excellent enantioseparation with the resolution more than 2.5 for all enantiomers was achieved on Chiralpak AD-H using mixture of heptane-propan-2-ol-diethylamine (980:20:1, v/v/v). The detection was carried out using fluorescence detector at excitation wavelength of 295 nm and emission wavelength of 273 nm. The influence of mobile phase composition, namely organic modifiers, additives, aliphatic alkanes and water content in mobile phase, on retention and enantioseparation was studied. Validation of the developed method including linearity, limit of detection, limit of quantification, precision, accuracy and selectivity was performed according to the International Conference on Harmonization guidelines. The advantage of the method is a good enantioseparation, short analysis time (less than 20 min) and therefore this method is suitable for routine determination of chiral purity of (R,R)-tapentadol in enantiopure active pharmaceutical ingredient.