Amino acid metabolism in human embryos.

The aim of this study was to find some relationship between amino acid metabolism and the embryo morphokinetic parameters studied via time-lapse analysis. Study included 48 human embryo samples and their culture media. Two groups of embryos were identified: embryos reached the 8-cell stage on day 3 (n=34) and embryos failed to develop at any point during the incubation (n=14). Amino acids levels were measured on day 3 of embryo development; using time-lapse analysis, the precise timing of embryo cleavage, synchrony of division, grade of fragmentation etc. were established. No statistically significant differences between dividing and arresting embryos were observed in terms of amino acids production/consumption and turnover. Amino acids which were part of the culture medium did not exhibit any statistically significant correlation with kinetic parameters with the exception of the grade of fragmentation on day 3; there were negative correlation with glutamate, and positive with glutamine, glycine and taurine. In some dividing and in some arresting embryos appeared new amino acids which strongly correlated with each other, with methionine, but not with any other amino acid that is a regular part of the culture medium.

[Changes in the levels of selected metabolites in the culture medium as a possible tool for the embryo selection in assisted reproduction]. / Zmeny hladin vybraných metabolitu v kultivacním médiu jako mozný nástroj pro selekci embryí v asistované reprodukci.

Despite the increasing success of infertility treatment methods of assisted reproduction, it still remains a problem how to select the best embryo that has the potential for further development and implantation. At the present time, embryo selection is based especially on morphological criteria. This approach is subjective; therefore there is a trend to find another more objective and robust method for embryo selection. Embryo metabolism can be used as an indicator of viability. This non-invasive method allows observing changes in the levels of different metabolites in culture medium before and after incubation of the only one embryo. The most mentioned substances are carbohydrates and amino acids as important components of culture medium. Carbohydrates serve predominantly as energy sources, whereas amino acids are precursors of protein and nucleotides, antioxidants, osmolytes, pH regulators etc. Several methods have been proposed for evaluating of embryo metabolic profile of embryo. There are many hypotheses for embryo selection according its metabolic profile.

A monitoring of allantoin, uric acid, and malondialdehyde levels in plasma and erythrocytes after ten minutes of running activity.

Uric acid is the final product of human purine metabolism. It was pointed out that this compound acts as an antioxidant and is able to react with reactive oxygen species forming allantoin. Therefore, the measurement of allantoin levels may be used for the determination of oxidative stress in humans. The aim of the study was to clarify the antioxidant effect of uric acid during intense exercise. Whole blood samples were obtained from a group of healthy subjects. Allantoin, uric acid, and malondialdehyde levels in plasma and erythrocytes were measured using a HPLC with UV/Vis detection. Statistical significant differences in allantoin and uric acid levels during short-term intense exercise were found. Immediately after intense exercise, the plasma allantoin levels increased on the average of 200 % in comparison to baseline. Plasma uric acid levels increased slowly, at an average of 20 %. On the other hand, there were no significant changes in plasma malondialdehyde. The results suggest that uric acid, important antioxidant, is probably oxidized by reactive oxygen species to allantoin. Therefore allantoin may be suitable candidate for a marker of acute oxidative stress.

Determination of retinol and α-tocopherol in human seminal plasma using an HPLC with UV detection.

Oxidative stress has been proposed as one of the potential causes for infertility in men. Retinol and α-tocopherol have an important role in the spermatozoa defences against oxidative stress. A method is described here for the simultaneous determination of retinol and α-tocopherol in human seminal plasma with a suitable sample preparation procedure to prevent retinol and α-tocopherol degradation. After adequate sample preparation, the samples were determined by reversed-phase column chromatography with UV detection. The analytical performance of this method was satisfactory. The intra-assay and inter-assay coefficients of variation were below 10%. The recoveries were as follows: 90.7% (CV 8.1%) for retinol and 98.2% (CV 4.8%) for α-tocopherol. No significant differences in both retinol and α-tocopherol concentration between the smokers and nonsmokers (15 ± 7 nm and 1.86 ± 0.29 µm versus 15 ± 6 nm and 1.93 ± 0.45 µm) were found. A selective high-performance liquid chromatography method for the determination of retinol and α-tocopherol in human seminal plasma was developed.

[Impact of oxidative stress on male infertility]. / Vliv oxidacního stresu na muzskou plodnost.

Reactive oxygen and nitrogen species (RONS) are necessary for the physiological function of sperm. Its concentration has to be kept on a level without the damage of cells. If this level is overdrawn sperm has pathological effect on many biological structures in the form of oxidative stress. Antioxidants have a key role for keeping of this balance. Oxidative stress is an important factor which causes problems with male fertility. The survey article is complexly concerned with the influence of RONS and antioxidants on male fertility. It outlines some possibilities of treatment and research on this actual issue of assisted reproduction.