Evaluation of sperm DNA fragmentation in male infertility.

Sperm DNA integrity could be considered a biological marker of sperm quality and may affect fertilization, embryonic development, and pregnancy outcome. The study aimed to investigate the connection between semen characteristics and sperm DNA damage in infertile patients. Standard semen analysis of 536 samples was carried out following the World Health Organization (WHO) 5th edition recommendations. Sperm DNA damage was assessed by the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, after preparation by direct swim-up. The slides were evaluated using a fluorescence microscope and the percentage of TUNEL-positive spermatozoa was expressed as the DNA fragmentation index (DFI). Patients were classified according to their DFI levels: group A (DFI < 15%) and group B (DFI ≥15%). Sperm total count, concentration, total and progressive motility, vitality, and normal morphology were significantly higher in group A compared to group B (p < 0.001). The results show a significant inverse correlation between DFI and patient's age, sperm total count, concentration, total and progressive motility, vitality and normal morphology. Higher DFI values were found to be strongly associated with poor sperm quality. In conclusion, combined with conventional semen analysis, assessment of sperm DFI could improve diagnostic accuracy and treatment management for patients with male infertility.

Comparison of Two Different Methods Used for Semen Evaluation: Analysis of Semen Samples from 1,055 Men.

The aim of this study was to evaluate whether there is a difference between gravimetrically and volumetrically measured semen samples and to assess the impact of semen volume, density, and sperm count on the discrepancy between gravimetric and volumetric methods. This study was designed in an andrology laboratory setting and performed on semen samples of 1,055 men receiving infertility treatment. Semen volume was calculated by gravimetric and volumetric methods. The total sperm count, semen density and sperm viability were also examined according to recent version of World Health Organization manual. The median values for gravimetric and volumetric measurements were 3.44 g and 2.96 ml respectively. The numeric difference in semen volume between 2 methods was 0.48. The mean density of samples was 1.01 ± 0.46 g/ml (range 0.90-2.0 g/ml). The numeric difference between 2 methods gets higher as semen volume increases (p < 0.001). Gravimetric and volumetric semen volume measurements were strongly correlated for all samples and for each subgroup of semen volume, semen density and sperm count, with minimum correlation coefficient of 0.895 (p < 0.001). In conclusion, the gravimetric measurement provides higher results than volumetric one and numeric differences between 2 methods increase as semen volume increases. However, further studies are needed to offer the use of gravimetrical method, which was thought to minimize laboratory errors, particularly for a high amount of semen samples.

Is thioredoxin reductase involved in the defense against DNA fragmentation in varicocele?

We aimed to investigate the role of thioredoxin reductase (TR) and inducible heat shock protein 70 (iHsp70) and their relationship with sperm quality in varicocele (VAR) patients. Semen samples were obtained from 16 subfertile men diagnosed as VAR and 10 fertile men who applied to the Andrology Laboratory of Istanbul Medical Faculty of Istanbul University. The sperm TR and iHsp 70 expression levels were determined using Western blot analysis. The TR activity of the sperm was assayed spectrophometrically. The sperm quality was evaluated both by conventional sperm analysis and by a terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) technique that assayed DNA-fragmented spermatozoa in semen samples. The percentage of TUNEL-positive spermatozoa in the VAR group (16.3%± 5.6%) was higher than that in the fertile group (5.5%± 1.9%). Significant inverse correlations were detected between the percentage of TUNEL-positive cells and both the concentration (r=-0.609; P=0.001) and motility (r=-0.550; P=0.004) of spermatozoa. Both the TR expression and activity were increased significantly in the VAR group (U=22.0; P=0.001 and U=33.5; P=0.012, respectively) as analyzed using the Mann-Whitney U Wilcoxon rank sum W test. Furthermore, significant positive correlations were found between TR expression and activity (r=0.406; P=0.040) and between TR expression and the percentage of TUNEL-positive cells (r=0.665; P=0.001). Sperm iHsp70 expression did not differ between the VAR and fertile groups. In conclusion, increased sperm TR expression might be a defense mechanism against apoptosis in the spermatozoa of men with VAR.