Catalase-like and superoxide dismutase-like activities in human seminal plasma.

Human spermatozoa are highly susceptible to oxidative injury but are naturally protected from such injury by the antioxidant properties of seminal plasma. We measured catalase-like and superoxide dismutase (SOD)-like activities in the seminal plasma of fertile and vasectomized men in order to gain insight into the potential source(s) and function(s) of these antioxidants in semen. Semen samples were obtained from fertile men ( n=11) and men post-vasectomy ( n=16). Catalase-like activity was measured by the decrease in hydrogen peroxide concentration after incubation with seminal plasma. SOD-like activity was measured as the inhibition of nitroblue tetrazolium reduction due to superoxide anion generation by xanthine plus xanthine oxidase. Mean seminal catalase-like activity (+/-1SD) in the fertile group was not significantly different from that of the post-vasectomy group (389+/-163 and 325+/-119 U/ml, respectively). Similarly, mean seminal SOD-like activity in the fertile group was not significantly different from that of the post-vasectomy group (37+/-10 and 36+/-10 U/ml, respectively). Our data suggest that the testis and epididymis are not an important source of catalase-like and SOD-like activities in semen. These findings indicate that antioxidants in semen are primarily of post-testicular origin and probably serve to protect ejaculated spermatozoa from oxidative stress such as that which occurs in the female reproductive tract.

Biologic variability of sperm DNA denaturation in infertile men.

OBJECTIVES: To examine sperm DNA denaturation (DD) in fertile and infertile men and assess the variability of conventional semen parameters and sperm DD in repeated semen samples from infertile men. METHODS: Twenty-one consecutive nonazoospermic, infertile men each submitted two semen samples, 2 to 6 weeks apart. We examined semen samples from consecutive fertile men (n = 10) presenting for vasectomy as controls. Standard semen parameters (World Health Organization criteria) and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa and expressed as the percentage of spermatozoa with denatured DNA) were monitored. RESULTS: Fertile men had a significantly higher sperm concentration and percentage of sperm motility and a significantly lower percentage of sperm with DD than did infertile men (36 +/- 5.2 x 10(6)/mL versus 12.5 +/- 2.2 x 10(6)/mL, 60.0% +/- 5.2% versus 30.1% +/- 4.1%, and 8.9% +/- 1.9% versus 20.3% +/- 2.5%, respectively, P <0.05). The sperm concentration, sperm motility, and percentage of spermatozoa with DD were not significantly different between the first and second semen samples from the infertile men. Sperm DD showed the lowest average within-subject coefficient of variation (SD/mean), followed by motility and concentration (coefficient of variation 21%, 24%, and 35%, respectively). CONCLUSIONS: Our data demonstrate that infertile men have significantly higher sperm DD compared with fertile men and that sperm DD exhibits a low coefficient of variation ( approximately 20%) on repeated assessment. These data suggest that sperm DD has a relatively low degree of biologic variability.

Free thiols in human spermatozoa: correlation with sperm DNA integrity.

OBJECTIVES: To examine the levels of sperm protamine free sulfhydryl or thiol (SH) groups and DNA denaturation (DD) in semen from fertile and infertile men.Methods. Semen samples were obtained from consecutive nonazoospermic men presenting for infertility evaluation (n = 66) and fertile men presenting for vasectomy (n = 10). The standard semen parameters (sperm concentration, motility, and morphology), sperm DD, and SH content were monitored. Sperm DNA integrity was evaluated by flow cytometry analysis of acridine orange-treated spermatozoa and expressed as the percentage of spermatozoa demonstrating denatured DNA. RESULTS: The mean (+/- SE) levels of sperm SH groups and the percentage of spermatozoa with DD were significantly higher in the infertile men than in the fertile men (SH groups 1083 +/- 97 and 570 +/- 101 nmol/10(6) spermatozoa, respectively; and DD 21% +/- 1.7% and 8.9% +/- 1.9%, respectively). The levels of sperm SH groups and DD correlated positively (r = 0.53). Also, the levels of sperm SH groups and DD correlated negatively with the standard semen parameters. CONCLUSIONS: Our data demonstrate that sperm SH content correlates positively with sperm DD and that significantly higher levels of sperm DD and SH content are found in infertile men than are found in fertile men. These data suggest that the enhanced susceptibility of sperm DNA to denaturation in infertile compared with fertile men may be associated with incomplete oxidation of the sperm SH groups.

Correlations between two markers of sperm DNA integrity, DNA denaturation and DNA fragmentation, in fertile and infertile men.

OBJECTIVE: To evaluate two different assays of human sperm DNA integrity, DNA denaturation (DD) and DNA fragmentation (DF), and to correlate these with standard semen parameters. DESIGN: Prospective, observational study. SETTING: University infertility clinic. PATIENT(S): Forty consecutive semen samples from 33 nonazoospermic men presenting for infertility evaluation and 7 fertile men presenting for vasectomy. INTERVENTION(S): Assessment of sperm concentration, motility, morphology, DD and DF. MAIN OUTCOME MEASURE(S): Sperm DD and DF in fertile and infertile men. RESULT(S): The mean (+/-SE) rates of DD and DF were significantly higher in infertile subjects compared to fertile controls, respectively: 25.4 +/- 3.0 vs. 10.2 +/- 2.3 (P=.028) and 27.6 +/- 2.5 vs. 13.3 +/- 2.5% (P=.016). DF and DD correlated strongly (r = 0.71, P<.0001). Also, DD and DF correlated negatively with standard semen parameters (concentration, motility, and morphology), the strongest correlation being with sperm motility. CONCLUSION(S): The strong correlation between sperm DD and DF, and the higher levels of sperm DNA damage in infertile compared with fertile men, indicate that male infertility is associated with poor sperm DNA integrity. Although infertile men may father children with assisted conception, fertilization with DNA-damaged spermatozoa may increase the risk of genetic disease in the offspring.

Influence of initial semen quality on the integrity of human sperm DNA following semen processing.

OBJECTIVE: To examine and compare the effects of density-gradient centrifugation on the integrity of sperm DNA from the semen of both fertile and infertile men. DESIGN: Prospective, observational study. SETTING: University infertility clinic. PATIENTS: Forty-four nonazoospermic, infertile men and nine fertile controls. INTERVENTIONS: Semen samples were processed by density-gradient centrifugation. Sperm motility and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen was processed. MAIN OUTCOME MEASURES: Sperm motility and DNA integrity. RESULTS: Following density-gradient centrifugation, mean sperm motility (+/-SEM) improved significantly compared to whole semen in samples from fertile and infertile men, respectively (71 +/- 6 vs. 49 +/- 7% and 56 +/- 3 vs. 44 +/- 3%, P<0.05). However, the percentage of sperm with denatured DNA increased compared to whole semen after processing of samples from infertile (25 +/- 3 vs. 15 +/- 2%, P<0. 01) but not fertile men (9 +/- 3 vs. 8 +/- 2%, P>0.05). CONCLUSIONS: Our data indicate that the potential detrimental effect of density-gradient centrifugation on sperm DNA integrity is related to the initial semen quality. These data urge us to examine our current sperm-processing techniques to minimize sperm DNA damage.

Antioxidant activity in the semen of fertile and infertile men.

OBJECTIVES: To evaluate catalase- and superoxide dismutase (SOD)-like activities in the seminal plasma of fertile and infertile men. METHODS: Semen samples were obtained from consecutive men presenting for vasectomy (n = 12) and infertility evaluation (n = 105) at our institution. Catalase-like activity was measured by the decrease in hydrogen peroxide after incubation with seminal plasma. SOD-like activity was measured as the inhibition of nitroblue tetrazolium reduction due to superoxide anion generation by xanthine plus xanthine oxidase. RESULTS: Mean seminal catalase-like activity (+/-SEM) in fertile men was not significantly different from that of infertile men (369 +/- 49 versus 326 +/- 17 U/mL, respectively). Mean SOD-like activity in the semen of infertile men was significantly greater than in the semen of fertile controls (46.7 +/- 1.5 versus 37.0 +/- 2.8 U/mL, respectively, P <0.05). CONCLUSIONS: Our data show that infertile men do not have deficient seminal plasma SOD- and/or catalase-like activity (two key antioxidants). These findings suggest that the high semen ROS levels in some infertile men are likely due to excessive generation of ROS rather than deficient ROS scavenging activity in semen.

Influence of semen processing technique on human sperm DNA integrity.

OBJECTIVES: To compare the effects of density-gradient centrifugation and swim-up technique on sperm DNA integrity. METHODS: Semen samples (n = 22) were obtained from consecutive nonazoospermic men presenting for infertility evaluation. Individual samples were divided into three aliquots (whole semen, density-gradient centrifugation, and swim-up) for subsequent analysis of sperm motility and DNA integrity. Sperm DNA integrity was evaluated by flow cytometry analysis of acridine orange-treated spermatozoa and expressed as the percentage of spermatozoa demonstrating denatured DNA. RESULTS: Mean sperm motility (+/-SEM) improved significantly after processing with two-layer density-gradient and swim-up compared with whole semen (65.6% +/- 4.0% and 73.0% +/- 3.0% versus 52.0% +/- 3.6%, respectively, P <0.005), with no significant difference in motility between Percoll-treated and swim-up-treated spermatozoa. In contrast, the percentage of spermatozoa with denatured DNA was reduced significantly in swim-up-treated but not in Percoll-treated spermatozoa compared with whole semen (4.8% +/- 1. 2% and 13.6% +/- 3.6% versus 10.1% +/- 2.3%, respectively, P <0. 0001). CONCLUSIONS: Although density-gradient centrifugation is comparable to swim-up technique in recovering spermatozoa with enhanced motility, spermatozoa recovered after swim-up possess higher DNA integrity. These data urge us to reexamine our current sperm processing techniques in order to minimize sperm DNA damage.

Potential adverse effect of semen processing on human sperm deoxyribonucleic acid integrity.

OBJECTIVE: To examine the effect of standard Percoll density-gradient centrifugation on human sperm DNA denaturation. DESIGN: Prospective, observational study. SETTING: University-based infertility clinic. PATIENT(S): Twenty-five nonazoospermic men. INTERVENTION(S): Semen samples (n = 25) were obtained from consecutively seen nonazoospermic men presenting for infertility evaluation. Samples were processed by two-layer and four-layer Percoll density gradients. Sperm motility and sperm chromatin structure (evaluated by flow cytometry analysis of acridine orange-treated spermatozoa) were monitored before and after semen processing. Sperm chromatin integrity was expressed as the percentage of spermatozoa that demonstrated denatured DNA. MAIN OUTCOME MEASURE(S): Sperm motility and DNA integrity. RESULT(S): Mean sperm motility improved significantly after processing with two-layer and four-layer Percoll gradients compared with whole semen (54% and 57% motility versus 44% motility, respectively). In contrast, the percentage of sperm with denatured DNA increased after processing with two-layer and four-layer Percoll gradients compared with whole semen (34% and 32% versus 18%, respectively). CONCLUSION(S): Our data demonstrate that the improvement seen in sperm motility after Percoll processing is not associated with a similar improvement in sperm DNA integrity. These data suggest that we reexamine current sperm processing techniques to minimize sperm DNA damage and the potential transmission of genetic mutations in assisted reproductive cycles.

Heat shock-induced acquisition of thermotolerance at the levels of cell survival and translation in Xenopus A6 kidney epithelial cells.

In this study we have investigated the acquisition of thermotolerance in a Xenopus laevis kidney A6 epithelial cell line at both the level of cell survival and translation. In cell survival studies, A6 cells were incubated at temperatures ranging from 22 to 35 degrees degrees C for 2 h followed by a thermal challenge at 39 degrees degrees C for 2 h and a recovery period at 22 degrees C for 24 h. Optimal acquisition of thermotolerance occurred at 33 degrees degrees C. For example, exposure of A6 cells to 39 degrees degrees C for 2 h resulted in only 3.4% survival of the cells whereas prior exposure to 33 degrees C for 2 h enhanced the survival rate to 69%. This state of thermotolerance in A6 cells was detectable after 1 h at 33 degrees C and was maintained even after 18 h of incubation. Cycloheximide inhibited the acquisition of thermotolerance at 33 degrees C suggesting the requirement for ongoing protein synthesis. The optimal temperature for the acquisition of translational thermotolerance also occurred at 33 degrees C. Treatment of A6 cells at 39 degrees C for 2 h resulted in an inhibition of labeled amino acid incorporation into protein which recovered to approximately 14% of control after 19 h at 22 degrees C whereas cells treated at 33 degrees C for 2 h prior to the thermal challenge recovered to 58% of control levels. These translationally thermotolerant cells displayed relatively high levels of the heat shock proteins hsp30, hsp70, and hsp90 compared to pretreatment at 22, 28, 30, or 35 degrees C. These studies demonstrate that Xenopus A6 cells can acquire a state of thermotolerance and that it is correlated with the synthesis of heat shock proteins.

Evolution of the T cell receptor beta repertoire from synovial fluid T cells of patients with juvenile onset rheumatoid arthritis.

OBJECTIVE: To determine the level of T cell clonal expansion and the proportion of T cells that persist over time in the synovial fluid (SF) of patients with juvenile onset rheumatoid arthritis (JRA). METHODS: We collected SF samples from each of 3 patients with JRA at 2 to 3 year intervals. To measure expression across the entire spectrum of Vbeta families in each of 7 fluids examined, we synthesized and amplified dscDNA from all 24 Vbeta families with a single reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The proportion of clonally expanded T cells and persistent T cells is low and variable among patients. CONCLUSION: The data are supportive of disease models not centered on T cells but centered on the changing nature of the disease over time.