DNA damage in spermatozoa from infertile men with varicocele evaluated by sperm chromatin dispersion and DBD-FISH

The Role of Seminal Oxidative Stress Scavenging System in the Pathogenesis of Sperm DNA Damage in Men Exposed and Not Exposed to Genital Heat Stress

Responding to the need for the verification of some experimental animal studies showing the involvement of oxidative stress in germ cell damage in the heat-induced testis, we investigated the possibility of a direct relationship between seminal oxidative stress markers (total antioxidant capacity, catalase activity, superoxide dismutase activity, and malondialdehyde concentration) and ejaculated sperm chromatin/DNA integrity (DNA fragmentation and chromatin condensation abnormalities) in distinct groups of men exposed and not exposed to prolonged scrotal hyperthermia. A statistical increase in the proportion of sperm with DNA fragmentation was observed in all the studied subgroups compared to the fertile men. In turn, the groups subjected to heat stress as professional drivers or infertile men with varicocele presented greater disturbances in the oxidative stress scavenging system than men not exposed to genital heat stress. Based on the comparative analysis of the studied parameters, we can conclude that alterations in the seminal oxidative stress scavenging system are directly engaged in the pathogenesis of ejaculated sperm DNA damage regardless of the intensity of the impact of thermal insult. To the best of our knowledge, this study, for the first time, revealed the co-existence of oxidative stress and sperm DNA damage in the semen of professional drivers.

DBD-FISH, an effective marker for detecting genotoxicity in buccal mucosa exfoliated cells of patients with oral cancer

Oral squamous cell carcinoma (OSCC) is characterized by increased genetic instability as an essential variable of event of neoplastic transformation. The aim of this study was to evaluate genomic instability in exfoliated cells from the buccal mucosa of patients with OSCC vs. the control group, using DNA Breakage Detection/Fluorescence In Situ hybridization (DBD-FISH). Exfoliated cells from the buccal mucosa were obtained from 38 patients with oral cancer (case group) and from 10 individuals without oral lesions (control group). DNA damage was evaluated by DBD-FISH using the whole-genome DNA probe and digital imaging analysis. Collaterally, HPV infection was determined utilizing the INNO-LiPA HPV kit. Patients with OSCC showed an increase in the hybridization signal five times more intense than that of the baseline level of DNA damage detected in control individuals. The best cutoff value for predicting oral squamous cell carcinoma was 67.46, and an Odds Ratio (OR) value of 87. HPV detection analysis revealed than one patient with OSCC (2.6%) was positive for HPV. All controls were negative HPV. In conclusion, DBD-FISH permitted the clear visualization of level high of DNA damage in the buccal epithelial cells of patients with OSSC respect to control group. Chromosome instability in oral mucosa may be an individual marker of malignant transformation in OSCC.

Sperm head morphometry and chromatin condensation are in constant change at seminiferous tubules, epididymis, and ductus deferens in bulls

The aim of this study was to evaluate the sperm head morphometry and chromatin condensation at different regions of the reproductive tract in bulls. Sperm smears of seminiferous tubules (ST), epididymis head (EH), body (EB), and tail (ET), and ductus deferens (DD) were stained with toluidine blue. Afterwards, the sperm head morphometry and chromatin alteration types were evaluated by a computational image analysis. Overall, spermatozoa of ST had lower (P < 0.05) area (A), perimeter (P), width (W), length (L), ellipticity (E), and Fourier harmonics (F0, F1, and F2). The chromatin decondensation (CD) and heterogeneity (CH) were higher (P < 0.05) in the ST region and decreased (P < 0.0001) during the migration along the reproductive tract (ST - DD direction). Considering the factors extracted (Factors 1 and 2) by the principal component analysis, the parameters A, P, W, L, and F0 were responsible for ∼36% of the Factor 1, while the E, F0, F1, and anterior-posterior symmetry (APS) contributed ∼27% to Factor 2. Both, CD and CH were associated with Factor 1 in the EH and ET regions and Factor 2 in the ST. Also, a well-defined difference between sperm heads collected from the ST and DD regions was observed by canonical analysis. The distribution of each chromatin alteration type was recorded. The proportion of normal sperm was lower (P < 0.05) in ST compared to other regions. Moreover, the chromatin influenced the morphometry and sperm heads with whole chromatin alteration type showed a smaller (P < 0.05) A, P, W, L, and E. In summary, the epididymal maturation is important for chromatin compaction and final morphometry of the sperm head. Also, the identification and quantification of the sperm chromatin condensation in different regions of reproductive tract can be used as potential biomarkers to predict the fertility in bulls.

Sperm DNA Fragmentation: A New Guideline for Clinicians

Sperm DNA integrity is crucial for fertilization and development of healthy offspring. The spermatozoon undergoes extensive molecular remodeling of its nucleus during later phases of spermatogenesis, which imparts compaction and protects the genetic content. Testicular (defective maturation and abortive apoptosis) and post-testicular (oxidative stress) mechanisms are implicated in the etiology of sperm DNA fragmentation (SDF), which affects both natural and assisted reproduction. Several clinical and environmental factors are known to negatively impact sperm DNA integrity. An increasing number of reports emphasizes the direct relationship between sperm DNA damage and male infertility. Currently, several assays are available to assess sperm DNA damage, however, routine assessment of SDF in clinical practice is not recommended by professional organizations. This article provides an overview of SDF types, origin and comparative analysis of various SDF assays while primarily focusing on the clinical indications of SDF testing. Importantly, we report four clinical cases where SDF testing had played a significant role in improving fertility outcome. In light of these clinical case reports and recent scientific evidence, this review provides expert recommendations on SDF testing and examines the advantages and drawbacks of the clinical utility of SDF testing using Strength-Weaknesses-Opportunities-Threats (SWOT) analysis.

Evaluation of the genotoxic effect of heavy metals in pigeons from urban and rural habitat in Monterrey, Mexico, using the chromatin dispersion assay

PURPOSE

Evaluate genotoxic effect of heavy metals on Pigeon Erythrocytes (PE) from urban and rural habitat (outside of the city) in Monterrey, Mexico, using the chromatin dispersion assay.

MATERIALS AND METHODS

We quantified metals concentrations (Cd, Hg, Cu and Pb) in tail feathers of 22 pigeons from an urban and a rural site in northeastern Mexico. DNA damage in peripheral blood erythrocytes was measured by chromatin dispersion assay in 13 pigeon living in urban habitat and in nine living in rural habitat as the control. MicroNucleus (MN) test was used to confirm levels of DNA damage.

RESULTS

Birds in urban habitat had highest concentrations in feathers for all the metallic elements analysed with respect to birds in rural habitat. Concentrations of Cu and Hg showed a significant increase (p < 0.05). Our results showed a significant increase of DNA damage in urban-habitat pigeons compared with that of pigeons in rural area. These results were confirmed by a MN test.

CONCLUSIONS

Our preliminary findings demonstrate that PE examination via chromatin dispersion assay is a reliable, precise and inexpensive morphological bioassay for evaluating environmental genotoxicity associated with heavy metals. Further studies for evaluating the individual participation of contaminants in DNA damage are needed.

Effects of percutaneous varicocele repair on testicular volume: results from a 12-month follow-up

Varicocele is a common finding in men. Varicocele correction has been advocated for young patients with testicular hypotrophy, but there is a lack of morphofunctional follow-up data. We assessed whether percutaneous treatment of left varicocele is associated with testicular "catch-up growth" in the following 12 months by retrospectively reviewing data from an electronic database of 10 656 patients followed up in our clinic between 2006 and 2016. We selected all young adults (<35 years) with left varicocele who underwent percutaneous treatment, had a minimum of 12 months' ultrasound imaging follow-up, and had no other conditions affecting testicular volume. One hundred and fourteen men (mean±standard deviation [s.d.] of age: 22.8 ± 5.4 years) met the inclusion and exclusion criteria. Left testicular hypotrophy (LTH), defined as a ≥20% difference between left and right testicular volume at baseline, was observed in 26 (22.8%) men. Participants with LTH (mean±s.d.: 14.5 ± 2.7 ml) had lower baseline testicular volume compared to those without LTH (mean±s.d.: 15.7 ± 3.8 ml; P = 0.032). Repeated measures mixed models showed a significant interaction between LTH and time posttreatment when correcting for baseline left testicular volume (β = 0.114, 95% confidence interval [CI]: 0.018-0.210, P = 0.020), resulting in a catch-up growth of up to 1.37 ml per year (95% CI: 0.221-2.516). Age at intervention was also associated with reduced testicular volume (-0.072 ml per year, 95% CI: -0.135--0.009; P = 0.024). Percutaneous treatment of left varicocele in young adults with LTH can result in catch-up growth over 1 year of follow-up. The reproductive and psychological implications of these findings need to be confirmed in longer and larger prospective studies.

Detection of DNA damage in pigeon erythrocytes using a chromatin dispersion assay

The monitoring of environmental genotoxicity requires the selection of model organisms as 'sentinels' as well as the development of sensitive and reliable tests for the assessment of DNA damage. The aims of this study were to quantify genomic DNA strand breakage in the erythrocytes of Columba livia induced by thermal stress using the modified chromatin dispersion test and to validate the results by alkaline comet assay and DNA breakage detection-fluorescence in situ hybridization (DBD-FISH). The chromatin dispersion test allowed for clear visualization of erythrocyte cells with DNA damage and of cells with no DNA damage. DNA damage increased significantly with increase in temperature. Additionally, we observed nuclear abnormalities associated with apoptosis, such as karyorrhexis (nuclear disintegration) and karyolysis (nuclear dissolution). These results were validated by alkaline comet assay and DBD-FISH. In conclusion, this procedure is a reliable, precise, and inexpensive morphological bioassay for routine quantitative analysis of DNA breakage in pigeon erythrocytes induced by thermal stress. This method could also be useful as a practical screening tool for genotoxicity testing in environmental care.

Evaluation of oxidative DNA damage in pigeon erythrocytes using DNA breakage detection-fluorescence in situ hybridization (DBD-FISH)

DNA breakage detection-fluorescence in situ hybridization (DBD-FISH) enables detection and quantification of DNA breakage in the entire genome or within specific DNA sequences in single cells. We used this method to visualize and evaluate DNA damage in pigeon erythrocytes that were induced by elevated temperature and hydrogen peroxide. We also examined morphological changes in the cell nuclei. DBD-FISH demonstrated a significant increase of DNA damage in a temperature dependent manner, which resulted in nuclear abnormalities associated with apoptotic cells. These cells gave strong nuclear fluorescent signals that indicated cell death.

Deterioration of semen quality and sperm-DNA integrity as influenced by cigarette smoking in fertile and infertile human male smokers-A prospective study

In modernized lifestyle smoking is one of the trendy, psychological, and socioeconomic scenarios of young adolescents mainly in the age of the reproductive stage. Based on a number of cigarettes smoked, age, and duration of the smoke, the study aims to search for the profound effects of smoking and its impact on semen parameters, sperm-DNA integrity, and fragmentation of sperm DNA with cotinine and apoptotic caspase-3 marker in the seminal plasma of fertile and infertile smokers. To determine oxidative damage by 8-hydroxy deoxyguanosine (8-OHdG) from isolated sperm DNA (steps: reactive oxygen species washing by nitro blue tetrazolium (NBT), sperm lysis, salt digestion, ethanol washing, and finally with high-performance liquid chromatography analysis). Level of DNA fragmentation (percentage) in native and intact DNA, the activity of caspase-3 in infertile smokers will be compared with the control group of nonsmokers. Also, the sperm viability was visualized by eosin-nigrosin and aniline blue staining. Cotinine is one of the best markers of smoking. The cotinine level (2224.24 ± 1.19 *** ng/mL), when abundant it negative correlates with morphology and rapid motility in infertile smokers than nonsmokers. Gel preprogram measured the sperm integrity and was found to be less in smokers than nonsmokers. The spermatic oxidative marker 8-OHdG was high and gave an R ² value of 0.9104 with morphology and 0.9007 for rapid motility of infertile sperm, respectively. Infertile smoking subjects (<10 cigarettes/day) had significant changes increase in sperm fragmentation, caspase-3, and cotinine while negative impact with motility, morphology, and pH of semen compared with fertile, infertile nonsmoking subjects.

Reduced sperm telomere length in individuals with varicocele is associated with reduced genomic integrity

Varicocele, defined as enlarged varicose veins in the scrotum, is the most common identifiable cause of male infertility. There are significant correlations between oxidative stress and varicocele-related infertility due to testicular hyperthermia, which can result in low sperm function. In addition, recent excessive oxidative stress can affect sperm telomere length and integrity of sperm DNA. Therefore, we assessed sperm telomere length as a potential marker of paternal genome integrity and leukocyte telomere length as an internal control (real-time PCR), along with sperm chromatin status (TUNEL and chromomycin A3 assay), and lipid peroxidation (Bodipy probe) in 18 infertile men with grade II or III varicocele, and 20 fertile men. Means of sperm parameters, sperm and leukocyte telomere length were significantly lower, while means of sperm DNA fragmentation, protamine deficiency, and lipid peroxidation were significantly higher in infertile men with varicocele compared to fertile men. Therefore, shortened telomere length in sperm and leukocytes is likely associated with increased oxidative stress related to the state of varicocele, which also accounts for increase in sperm DNA fragmentation. Thus, assessment of leukocyte telomere length could be taken as an indicator of antioxidant capacity in an individual, which also affects sperm function.

Comparison of main molecular markers involved in autophagy and apoptosis pathways between spermatozoa of infertile men with varicocele and fertile individuals

Abnormal dilatation and tortuosity of the pampiniform plexus within the spermatic cord are termed varicocele which leads to impaired spermatogenesis due to heat-related oxidative stress and cell death. Previously, it was shown that both apoptosis and autophagy pathways were activated by heat in germ cells of mouse in vivo and in vitro. But, status of these pathways is not clear in chronic state of heat stress such as varicocele. Therefore, we aimed to access sperm apoptotic markers (active caspases 3/7 and DNA fragmentation), and autophagic markers (Atg7 and LC3 proteins) as primary outcomes, and also sperm parameters and protamine deficiency as secondary outcomes between 23 infertile men with varicocele and 16 fertile individuals. Sperm parameters were assessed according to World Health Organization 2010 protocol. Apoptotic markers (active caspases 3/7 and DNA fragmentation), autophagic markers (Atg7 and LC3 proteins), and protamine deficiency were evaluated by flow cytometry, fluorescence microscope, and western blotting techniques. Mean of autophagy and apoptosis markers, and also protamine deficiency have significantly increased in infertile men with varicocele compared to fertile individuals, but autophagy and apoptosis markers did not significantly correlate with each other. In conclusion, it seems that both apoptosis and autophagy pathways are independently active in spermatozoa of infertile men with varicocele.

Morphometric comparison by the ISAS® CASA-DNAf system of two techniques for the evaluation of DNA fragmentation in human spermatozoa

DNA fragmentation has been shown to be one of the causes of male infertility, particularly related to repeated abortions, and different methods have been developed to analyze it. In the present study, two commercial kits based on the SCD technique (Halosperm ® and SDFA) were evaluated by the use of the DNA fragmentation module of the ISAS ® v1 CASA system. Seven semen samples from volunteers were analyzed. To compare the results between techniques, the Kruskal-Wallis test was used. Data were used for calculation of Principal Components (two PCs were obtained), and subsequent subpopulations were identified using the Halo, Halo/Core Ratio, and PC data. Results from both kits were significantly different (P < 0.001). In each case, four subpopulations were obtained, independently of the classification method used. The distribution of subpopulations differed depending on the kit used. From the PC data, a discriminant analysis matrix was obtained and a good a posteriori classification was obtained (97.1% for Halosperm and 96.6% for SDFA). The present results are the first approach on morphometric evaluation of DNA fragmentation from the SCD technique. This approach could be used for the future definition of a classification matrix surpassing the current subjective evaluation of this important sperm factor.

Tracing of zinc and iron in experimentally induced varicocele: correlation with oxidative, nitrosative and carbonyl stress

This study was designed to evaluate how varicocele (VCL) can time dependently induce zinc (Zn) and iron (Fe) toxicity in testicular tissue and to analyse the relation between heavy metals toxicity and lipid peroxidation, sperm DNA damage, nitrosative and carbonyl stresses. Twenty-four mature male Wistar rats were divided into control-sham and test groups, which were then submitted to experimentally induced VCL. Non-VCL-induced rats were considered as control-sham. The test groups were subdivided into three groups based on the sample collecting date (2, 6 and 8 months after VCL induction). Zn and Fe distribution in testicles, DNA ladder for sperm DNA fragmentation, testicular total antioxidant capacity (TAC), malondialdehyde (MDA), nitrite oxide (NO) and carbonyl groups (CG) were analysed. A significant (p < .05) enhancement in the percentage of tubules with negative tubular repopulation, differentiation and spermiogenesis indices was revealed. The VCL increased Zn and Fe distribution in testicles. The VCL, time dependently, reduced sperm count, motility and enhanced sperm DNA damage (p < .05). The VCL downregulated the testicular TAC and enhanced the MDA, NO and CG contents. Our data showed that the VCL results in intensive Fe and Zn toxicities. Produced Zn- and Fe-mediated-oxidative stress increases sperm DNA damage associated with NO and CG-induced stresses.

An Update on Oxidative Damage to Spermatozoa and Oocytes

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization.