Malonaldehyde formation and DNA fragmentation: two independent sperm decays linked to reactive oxygen species

Risk of embryo aneuploidy is affected by the increase in sperm DNA damage in recurrent implantation failure patients under ICSI-CGH array cycles

This study investigates the relationship between sperm DNA damage in recurrent implantation failure (RIF) patients treated with comparative genomic hybridisation array-intracytoplasmic sperm injection (CGH array-ICSI) cycles and embryo aneuploidy screening. Forty-two RIF couples were selected. Sperm DFI was measured using TUNEL by flow cytometry. Two groups were defined as follows: (i) sperm with high DFI (> 20%); and (ii) low DFI (< 20%). Semen parameters, total antioxidant capacity (TAC), and malondialdehyde formation (MDA) were also measured in both groups. Following oocyte retrieval and ICSI procedure, blastomere biopsy was performed at the 4th day of development and evaluated with CGH-array. The high DFI group had a significant (p = 0.04) increase in the number of aneuploid embryos compared to the low one. According to Poisson regression results, the risk of aneuploidy embryos in the high DFI group was 55% higher than the low DFI group (RR = 1.55; 95% CI = 1.358-1.772). Moreover, chromosomal analysis showed an elevation of aneuploidy in chromosomes number 16 and 20 in the high DFI group compared to the low DFI group (p < 0.05). The high DFI in RIF patients may significantly affect the risk of aneuploidy embryos. Therefore, embryo selection by CGH-array should be considered for couples with high levels of sperm DNA fragmentation.

The Antitumor and Toxicity Effects of Ruthenium(II) Complexes on Heterotopic Murine Colon Carcinoma Model

The aim of the present study was to examine the antitumor and toxicity effects of ruthenium(II) complexes, [Ru(Cltpy)(en)Cl][Cl] (Ru-1) and [Ru(Cl-tpy)(dach)Cl][Cl] (Ru-2) on heterotopic murine colon carcinoma model.

For tumor induction, 1×106 CT26 cells suspended in 100 μl of DMEM were injected subcutaneously into flank of male BALB/c mice. Treatment groups were as follows: Ru-1, Ru-2, oxaliplatin and control (saline). The intraperitoneal administration of the tested complexes began on 6th day after CT26 cells inoculation. Each complex was administered at dose of 5 mg/kg, twice weekly, four doses in total. To assess toxicity, serum values of urea, creatinine, AST and ALT were determined and histopathological analysis of organs and tumor were performed. In order to assess the effects of Ru(II) complexes on markers of oxidative stress and antioxidant defense system, we determined the TBARS, GSH, SOD and CAT in the homogenate of tumor, heart, liver, lungs and kidney tissues.

The findings indicate that Ru-1 and Ru-2 exerts equal or better antitumor activity in comparison with oxaliplatin, but with pronounced toxic effects such as reduced survival rate, cardiotoxicity, nephrotoxicity and hepatotoxicity. The increased index of lipid peroxidation in the tissues of the kidneys and heart, but decreased in tumor tissue, after Ru(II) complexes administration, indicates the importance of the induction of oxidative stress as a possible mechanism of nephrotoxicity and cardiotoxicity, but not the mechanism by which they realize antitumor activity.

Additional studies are needed to elucidate the mechanism of antitumor activity and toxicity of the Ru(II) complexes.

Effects of varenicline on lung tissue in the animal model

OBJECTIVE

This study aimed to investigate acute and chronic effects of varenicline on lung tissue in an experimental study.

METHODS

A total of 34 rats were randomly allocated into study (varenicline) and control groups. The rats were divided into two groups (i) control group, (ii) varenicline group. Then, the rats in the each group were sub-divided equally in turn as acute (C1; V1) and chronic (C2; V2) ; all rats of acute and chronic groups were sacrificed under the anesthesia on the 45th day for acute group [C1 (n=5) and V1 (n=12)] and the 90th day for chronic group [C2 (n=5) and V2 (n=12)], respectively. Thus, biochemical and histopathological analysis were carried out.

RESULTS

Thirty four rats completed the study, 24 were in varenicline group and 10 were in control group. In chronic exposure to varenicline, oxidant levels comprising of malondialdehyde (MDA), and myeloperoxidase (MPO) increased and superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione peroxidase (GPx) levels, named as antioxidants, decreased significantly when compared to the control group. MDA and MPO levels were also significantly higher and SOD, CAT, GPx, GSH levels were also significantly lower in chronic varenicline group when compared to acute varenicline group. These findings were also supported by histopathological observations.

CONCLUSION

This is the first study, which evaluated pulmonary effects of varenicline experimentally on an animal model. It was observed that chronic varenicline treatments cause inflammation and lung cell injury.

Protective effect and mechanisms of ginsenoside Rg1 against MDA-suppressed proliferation in mesenchymal stem cells derived from murine bone marrow

Objective: The present study was designed to investigate the cytoprotective effects of ginsenoside Rg1 (GS-Rg1) against malondialdehyde (MDA)-suppressed proliferation of the mesenchymal stem cells (MSCs) and its possible mechanisms in vitro.

Methods: Murine bone marrow-derived MSCs were treated with GS-Rg1 (10, 50, 100[Formula: see text]mg/L) for 24[Formula: see text]h before being incubated with MDA in vitro, CFU-Fassay, the cell viability and BrdU incorporation assay were examined, the expression of cyclin-dependent kinase 2 (CDK2), p21 and cyclin E of MSC were examined by Q-RT-PCR and Western blotting.

Results: The results showed that the number and size of murine bone marrow MSC colonies, the number of colony-forming cells, methyl thiazolyltetrazolium (MTT) absorbed value greatly and percentage of BrdU-positive cells increased significantly in MSC pretreated with GS-Rg1. GS-Rgl pretreatment markedly decreased the expression level of p21 and increased the expression of CDK2 and cyclin E. GS-Rg1 protects MSCs from MDA-suppressed proliferation.

Conclusion: The protective mechanism could be related to its ability to increase the expression of CDK2 and cyclin E, and to reduce the expression of p21.

Accuracy of human sperm DNA oxidation quantification and threshold determination using an 8-OHdG immuno-detection assay

STUDY QUESTION

Can a discriminant threshold be determined for human sperm DNA oxidation?

SUMMARY ANSWER

A discriminant threshold was found with 65.8% of 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive sperm cells and a mean intensity of fluorescence (MIF) of 552 arbitrary units.

WHAT IS KNOWN ALREADY

Oxidative stress is known to interfere with sperm quality and fertilizing capacity. However, current practice does not include the routine determination of oxidative DNA damage in spermatozoa; optimized consensus protocols are lacking and no thresholds of normality have been established.

STUDY DESIGN, SIZE, DURATION

Intra- and inter-method comparisons between four protocols (I-IV) were conducted to determine the most relevant and efficient means of assessing human sperm 8-OHdG content. Tests of assay repeatability, specificity, sensitivity and stability were performed to validate an optimized methodology for routine diagnostic use.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This prospective study compared three immuno-detection methods including immunocytochemistry, fluorescence microscopy and flow cytometry. Sperm DNA oxidation for 80 patients was determined relative to semen parameters and clinical conditions, using the selected immuno-detection protocol in comparison with a commercial kit. These patients (age 35 ± 1 years: mean ± SEM) presented with normozoospermic (n = 40) or altered parameters (necro- or/and astheno- or/and teratozoospermia or/and leukocytospermia).

MAIN RESULTS AND THE ROLE OF CHANCE

Significant positive Pearson and Spearman correlations were determined for 8-OHdG values and sperm parameters using protocol III. A notable high and positive correlation was revealed for MIF with BMI and leukocyte concentration. Protocol III was the most discriminating method regarding assay repeatability, specificity, sensitivity, stability and reliability for sperm parameter alterations, in particular leukocytospermia according to parametric or non-parametric tests, effect-size determinations and factorial analysis such as principal component analysis and factor discriminant analysis. Of interest is that 39% of the subjects with 'pathological' sperm DNA oxidation values were normozoospermic.

LIMITATIONS, REASONS FOR CAUTION

The oligozoospermic population was not evaluated in this study because insufficient material was available to carry out the comparisons. However, spermatozoa concentration was taken into account in the statistical analysis.

WIDER IMPLICATIONS OF THE FINDINGS

Our study is the first validation of a protocol to determine a discriminant threshold for human sperm DNA oxidation. The protocol's detection accuracy for 8-OHdG human sperm DNA residues, stability over time, and relationship to human sperm quality were demonstrated. The assay should find application in the diagnosis of male factor infertility associated with oxidative stress.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by institutional grants from the CNRS, INSERM and Université Clermont Auvergne (to J.R.D.) and by Clermont-Ferrand Hospital-CECOS research funds (to L.J. and F.B.). P.G., A.M., R.J.A. and J.D. are, respectively, CEO, scientific director and scientific advisors of a US-based biotech company (Celloxess, Princeton, NJ, USA) involved in preventative medicine with a focus on the generation of antioxidant oral supplements.

Semen quality and sperm DNA damage associa -revised - final-finalted with oxidative stress in relation to exposure to polycyclic aromatic hydrocarbons

The cross-sectional study aimed to assess whether oxidative stress induced by exposure to polycyclic aromatic hydrocarbons (PAHs) affect semen quality and sperm DNA integrity. A total of 106 who met the inclusion criteria, were recruited from a coke-oven plant during their annual health checkup. The human subjects were grouped into the high exposure group, the low exposure group and the control based on PAH concentrations surrounding their employment locations. Semen quality, oxidative stress status, and sperm DNA damage [DNA fragmentation and 8-hydroxy-2'-deoxyguanosine (8-oxodGuo)] were assessed. Urinary 1-hydroxypyren (1-OHP) was used to assess human subject exposure to PAHs. The high exposure group experienced significantly lower sperm motility and normal morphology than the control (P = 0.046 and 0.049, respectively). The high exposure group also had significantly higher 8-oxoGuo concentrations in sperm than the control (P = 0.027). Urinary 1-OHP concentration was associated with decreased motility and less normal morphology, along with increased sperm oxidative damage and ROS concentrations. Oxidative stress induced by exposure to PAHs was associated with decreased sperm quality.

Ameliorative effects of rutin against cisplatin-induced reproductive toxicity in male rats

BACKGROUND

Cisplatin (CP) or cis-diammine dichloroplatinum (II) is a platinum based standard antineoplastic drug which is used against variety of solid tumors and neoplasms. The present study aimed to evaluate the shielding effects of rutin against CP induced testicular toxicity in rats.

METHODS

28 male rats were divided into four groups. First group was given saline orally while second group received intra-peritoneal (i.p) injection of cisplatin (7 mg/kg) on day first and received saline for next 13 days. Third group received i.p injection of cisplatin at day one and treated with rutin (75 mg/kg) orally for next 13 days. Fourth group was treated with rutin orally for 13 days. Animals were sacrificed on 14th day and reproductive organs were analyzed for various parameters.

RESULTS

Cisplatin treatment resulted in a significant decrease in daily sperm production, decrease in head length and % DNA in head, reduction of epithelial cell height, tubular diameter, reduction of the number of spermatogonia, spermatocytes and spermatids, increase in the thiobarbituric acid reactive substances (TBARS) and oxidative stress in testicular tissues, and change of the intra-testicular testosterone concentrations. Rutin co-treatment resulted in reversing cisplatin effect on DNA damage, sperm count, histological and biochemical parameters.

CONCLUSION

These results indicated that rutin co-treatment could ameliorate cisplatin-induced reproductive toxicity in male rats.

Curcumin improves neurofunctions of 6-OHDA-induced parkinsonian rats

Our previous study has demonstrated that curcumin (CM), a natural ingredient isolated from Zingiberaceae, exerts the effect of inhibiting hippocampal injury in 6-hydroxydopamine (6-OHDA)-induced parkinsonian rat. However, the potential effect of CM on 6-OHDA-injured substantia nigra (SN) needs to be investigated. This study aimed to further evaluate the therapeutic effectiveness of CM against damaged SN in rats. Methodologically, Parkinson's disease (PD) rat was prepared by using a surgical approach of injecting 6-hydroxydopamine (6-OHDA) into the SN. Morris water maze, open-field assays, and rotarod test were used to assess the neurobehavioral manifestations. Neurotransmitter contents in the SN were determined by using the biochemical tests. Western blotting was employed to evaluate the target protein expressions. The representative data showed that CM protected against 6-OHDA-induced neural impairments in the SN, as evidenced by improved memory abilities, elevated intercalatum levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and reduced concentration of malonaldehyde (MDA). In addition, dopamine (DA) and acetylcholine (ACh) levels were increased in the SN. Moreover, intercalatum heat shock protein 70 (HSP70) was lowered, while basic fibroblast growth factor (bFGF), nerve growth factor (NGF) and receptor tyrosine kinase A (TrkA) expressions were up-regulated, respectively. Taken together, the findings indicate that curcum in exerts neuroprotection in the SN via ameliorating neurofunctions of PD rats.

Evaluation of the cardiovascular effects of varenicline in rats

BACKGROUND

Cardiovascular disease is an important cause of morbidity and mortality among tobacco users. Varenicline is widely used worldwide to help smoking cessation, but some published studies have reported associated cardiovascular events.

OBJECTIVE

To determine the cardiovascular toxicity induced by varenicline in rats.

MATERIALS AND METHODS

We randomly separated 34 rats into two groups: 1) the control group (given only distilled water orally, n=10) and the varenicline group (given 9 μg/kg/day varenicline on days 1-3, 9 μg/kg twice daily on days 4-7, and 18 μg/kg twice daily on days 8-90 [total 83 days], n=24). Each group was then subdivided equally into acute and chronic subgroups, and all rats in these groups were euthanized with anesthesia overdose on days 45 and 90, respectively. Body and heart weights, hemodynamic (mean oxygen saturation, mean blood pressure, and heart rate, electrocardiographic (PR, QRS, and QT intervals) biochemical (oxidants and antioxidants), and histopathological analyses (including immunostaining) were performed.

RESULTS

Acute varenicline exposure resulted in loss of body weight, while chronic varenicline exposure caused heart weight loss and decreased mean blood pressure, induced lipid peroxidation, and reduced antioxidant activity. Both acute and chronic varenicline exposure caused impairment of mean oxygen saturation. QT interval was prolonged in the chronic varenicline group, while PR interval prolongation was statistically significant in both the control and acute varenicline groups. Caspase-9 activity was also significantly increased by chronic exposure. Moreover, histopathological observations revealed severe morphological heart damage in both groups.

CONCLUSION

Adverse effects of chronic varenicline exposure on cardiovascular tissue were confirmed by our electrocardiographic, biochemical, and histopathological analyses. This issue needs to be investigated with new experimental and clinical studies to evaluate the exact mechanism(s) of the detrimental effects of varenicline. Physicians should bear in mind the toxic effects of varenicline on the cardiovascular system when prescribing it for smoking cessation.

Impact of sperm genome decay on Day-3 embryo chromosomal abnormalities from advanced-maternal-age patients

Infertile male patients often exhibit unconventional semen parameters, including DNA fragmentation, chromatin dispersion, and aneuploidy-collectively referred to as sperm genome decay (SGD). We investigated the correlation of SGD to embryo chromosomal abnormalities and its effect on clinical pregnancy rates in patients with advanced maternal age (AMA) (>40 years) who were undergoing intracytoplasmic sperm injection-preimplantation genetic screening (ICSI-PGS). Three groups were assessed: patients with AMA and male partners with normal sperm (AMA-N); AMA patients and male partners presenting with SGD (AMA-SGD); and young fertile female patients and male partners with SGD (Y-SGD). We found a significant increase in embryonic chromosomal abnormalities-polyploidy, nullisomy, mosaicism, and chaotic anomaly rates-when semen parameters are altered (76% vs. 67% and 66% in AMA-SGD vs. AMA-N and Y-SGD groups, respectively). Statistical analysis showed a correlation between SGD and aneuploidies of embryonic chromosomes 13, 16, 21, X, and Y, as well as negative clinical outcomes. Incorporation of molecular sperm analyses should therefore significantly minimize the risk of transmission of chromosomal anomalies from spermatozoa to embryos, and may provide better predictors of pregnancy than conventional sperm analyses. We also demonstrated that an ICSI-PGS program should be implemented for SGD patients in order to limit transmission of chromosomal paternal anomalies and to improve clinical outcome.

Toxic effects of systemic cisplatin on rat eyes and the protective effect of hesperidin against this toxicity

CONTEXT

In the present study, cisplatin (CP) induced eye toxicity and the beneficial effect of hesperidin (HP) was investigated.

METHODS

Twenty-eight rats were equally divided into four groups; the first group was kept as control. In the second and third group, CP and HP were given at the doses of 7 mg/kg and 50 mg/kg/d, respectively. In the fourth group, CP and HP were given together at the same doses. Tissue samples were collected on day 14 of CP treatment.

RESULTS

The results demonstrated that CP caused a significant increase in thiobarbituric acid reactive substances (TBARS) levels and decrease of glutathione levels and antioxidant enzyme activity (catalase, superoxide dismutase and glutathione peroxidase) in eye tissues compared to other groups, HP prevented these effects of CP. Besides, CP led to histopathological damage in the retina and cornea. On the other hand, HP treatment prevented histopathological effects of CP.

CONCLUSION

CP had severe dose-limiting toxic effects and HP treatment can be beneficial against the toxic ocular effects of CP. Thus, it appears that co-administration of HP with CP may be a useful approach to attenuate the negative effects of CP on the eye.

Toxicity assessment of the water used for human consumption from the Cameron/Tuba City abandoned uranium mining area prior/after the combined electrochemical treatment/advanced oxidation

The purpose of this work was detailed physicochemical, radiological, and toxicological characterization of the composite sample of water intended for human consumption in the Cameron/Tuba City abandoned uranium mining area before and after a combined electrochemical/advanced oxidation treatment. Toxicological characterization was conducted on human lymphocytes using a battery of bioassays. On the bases of the tested parameters, it could be concluded that water used for drinking from the tested water sources must be strictly forbidden for human and/or animal consumption since it is extremely cytogenotoxic, with high oxidative stress potential. A combined electrochemical treatment and posttreatment with ozone and UV light decreased the level of all physicochemical and radiological parameters below the regulated values. Consequently, the purified sample was neither cytotoxic nor genotoxic, indicating that the presented method could be used for the improvement of water quality from the sites highly contaminated with the mixture of heavy metals and radionuclides.

Effect of antioxidants on sperm genetic damage

According to worldwide statistics, between one in four and one in five couples have fertility problems. These problems are equally distributed between males and females. Modern lifestyle has obviously increased these problems: endocrine-disrupting chemicals, such as plastic polymer catalysts, alkylphenols, phthalates and so on, and cosmetic additives seem to be strongly involved in this fertility problem. Many of these compounds increase oxidative stress (OS) and thus impair spermatogenesis. The oocyte has only a finite capacity, decreasing with maternal age, to repair sperm-borne decays. To decrease this DNA repair burden, reducing the sperm DNA damages linked to OS is tempting. Antioxidant vitamins are often given haphazardly; they are not very efficient and potentially detrimental. A detailed analysis of the sperm nucleus is mandatory (DNA fragmentation or lack of nuclear condensation) prior to any treatment. Here we discuss new concepts in OS and the corresponding therapeutic approaches.

Anti-inflammatory Montelukast prevents toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin: Oxidative stress, histological alterations in liver, and serum cytokine levels

This study aimed to investigate the potential beneficial effects of the montelukast (ML) on oxidative stress and histological alterations in liver tissues and cytokine levels in rats intoxicated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Rats were divided randomly into four equal groups (control, TCDD, ML, TCDD + ML). TCDD were administered by gavages dissolved in corn oil at the doses of 2 µg/kg/week, and ML was given intraperitoneally at the dose of 10 mg/kg/day. Oxidative status, histological alterations, and cytokine levels were analyzed on day 60. The results showed that although TCDD induced oxidative stress via significant increase in formation of thiobarbituric acid reactive substance, it caused a significant decline in glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) levels in liver. Besides, TCDD led to significant histopathological damage in liver and serum cytokine levels alterations (increase in tumor necrosis factor α and interleukin 1β levels). In contrast, ML treatment reversed oxidative effects of TCDD by increasing the levels of GSH, CAT, and SOD and decreasing the formation of TBARS. Also, it can normalize the levels of histological and cytokine alterations induced by TCDD. In conclusion, it was determined that TCDD exposure caused adverse effects on cytokine levels, histological alterations, and oxidative stress in rats. However, ML treatment partially eliminated toxic effects of TCDD. Thus, it was judged that coadministration of ML with TCDD may be useful to attenuate the negative effects of TCDD.

Myelophil attenuates brain oxidative damage by modulating the hypothalamus-pituitary-adrenal (HPA) axis in a chronic cold-stress mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Myelophil is composed of Astragali Radix and Salviae Miltiorrhizae Radix, according to the long traditional pharmacological practices, and it has been used for patients with chronic fatigue-associated symptoms including concentration problem or memory loss.

AIM OF THE STUDY

This study aimed to evaluate the clinical relevance of Myelophil on brain oxidative damage using a chronic cold stress mice model.

MATERIAL AND METHODS

Balb/c mice were subjected to cold stress (4°C for 4h) six times per week for 2 weeks with or without oral administration of Myelophil (50, 100, or 200mg/kg), or ascorbic acid (50mg/kg).

RESULTS

Chronic cold stress induced histopathological hippocampal apoptosis with drastically increased serum levels of total reactive oxygen species and nitric oxide, as well as brain lipid peroxidation levels, protein carbonyl, and caspase-3/7 activity. These alterations were significantly ameliorated by Myelophil treatment. Myelophil administration significantly recovered the depleted glutathione and its enzymes, superoxide dismutase activity, and catalase protein and gene expression levels. Serum levels of corticosterone, dopamine, and adrenaline were notably altered by chronic cold stress but were significantly ameliorated by Myelophil treatment. Myelophil also normalized alterations in tumor necrosis factor-α, interleukin (IL)-1β, and IL-10 gene expression and protein levels. Chronic cold stress up-regulated gene expression levels of phenylethanolamine N-methyltransferase and monoamine oxidase-B, and glucocorticoid receptors in the hypothalamus and hippocampus, respectively, whereas Myelophil treatment completely normalized these levels.

CONCLUSIONS

These results suggest that Myelophil has potent pharmaceutical effects against chronic cold-stress-induced brain damage by relieving oxidative stress and inflammation and regulating stress hormones in mice.

Development of a specific method to evaluate 8-hydroxy,2-deoxyguanosine in sperm nuclei: relationship with semen quality in a cohort of 94 subjects

Oxidative stress (OS) is involved in many disoders including male infertility. Human spermatozoa are very sensitive targets of reactive oxygen species (ROS) and most sperm functions are impaired in the case of OS. In addition unbalanced production of ROS is considered one of the most important causes of sperm DNA fragmentation, a semen trait of infertile men. The relationship between oxidative damage and semen quality is partially controversial, probably due to the different methods and/or targets used to reveal the OS. In this study, by fluorescence microscopy and flow cytometry, we compared two methods to reveal 8-hydroxy,2-deoxyguanosine (8-OHdG), the hallmark of oxidative DNA damage: an immunofluorescence method and the commercial OxyDNA kit. We found that although both methods localized the labelling in sperm nuclei they yielded different measures, and only with the immunofluorescence method was the labelling specific for sperm 8-OHdG. The immunofluorescence method, coupled to flow cytometry, was thus selected to analyse the 8-OHdG content in semen samples from 94 subfertile patients and to investigate the relationship with semen quality. We found that the percentages of spermatozoa with 8-OHdG (mean±s.d., 11.4±6.9%) were related to sperm count (Pearson's correlation coefficient (r)=−0.27, P=0.04 (ANOVA and student's t-test)), motility (progressive: r=−0.22, P=0.04; non-progressive: r=0.25, P=0.01), and normal morphology (r=−0.27, P=0.01). In conclusion, we demonstrate that immunofluorescence/flow cytometry is a reliable and specific method to detect 8-OHdG at single-cell level and show that oxidative damage only partially overlaps poor semen quality, suggesting that it could provide additional information on male fertility with respect to routine semen analysis.

Oxidative stress and fertility: incorrect assumptions and ineffective solutions?

One of the most important concerns in assisted reproduction (ART), and in particular ICSI, is the quality of sperm DNA. Oxidative stress is one of the major causes of damage to DNA and attempting to reduce generation of DNA damage related to reactive oxygen species (ROS) through consumption of antioxidants is often tempting. However, current antioxidant treatments, given irrespectively of clinically quantified deficiencies, are poorly efficient, potentially detrimental and over-exposure is risky. Here we discuss new treatments in relation to present day concepts on oxidative stress. This discussion includes stimulation of endogenous anti-ROS defense i.e. glutathione synthesis and recycling of homocysteine, the epicentre of multiple ROS-linked pathologies.

Protective effects of protocatechuic acid on TCDD-induced oxidative and histopathological damage in the heart tissue of rats

2,3,7,8-Tetracholorodibenzo- p-dioxin (TCDD) is a highly toxic environmental contaminant that causes severe toxic effects in animal and human. In this study, we investigated the toxic effects of TCDD and the preventive effects of protocatechuic acid (PCA), a widespread phenolic compound, in the heart tissue of rats. For this purpose, 3–4 months old 28 rats with 280–310 g body weights were equally divided into 4 groups (control, TCDD, PCA, TCDD + PCA group). A 2 μg/kg dose of 2,3,7,8-TCDD and 100 mg/kg dose of PCA were dissolved in corn oil and given orally to the rats for 45 days. The results indicated that TCDD induced oxidative stress by increasing the level of thiobarbituric acid reactive substance and by decreasing the levels of glutathione, catalase, glutathione peroxidase and superoxide dismutase in the heart tissue of rats. In contrast, PCA treatment prevents the toxic effects of TCDD on oxidative stress. In addition, histopathological alterations such as necrosis and hemorrhage occurred in TCDD group, and PCA treatment partially prevents these alterations in heart tissue. In this study, it was concluded that TCDD exposure led to toxic effects in heart tissue and PCA treatment could prevent the toxicity of TCDD.

Mechanisms and clinical correlates of sperm DNA damage

Among the different DNA anomalies that can be present in the male gamete, DNA fragmentation is the most frequent, particularly in infertile subjects. There is now consistent evidence that a sperm containing fragmented DNA can be alive, motile, morphologically normal and able to fertilize an oocyte. There is also evidence that the oocyte is able to repair DNA damage; however, the extent of this repair depends on the type of DNA damage present in the sperm, as well as on the quality of the oocyte. Thus, it is important to understand the possible consequences of sperm DNA fragmentation (SDF) for embryo development, implantation, pregnancy outcome and the health of progeny conceived, both naturally and by assisted reproductive technology (ART). At present, data on the consequences of SDF for reproduction are scarce and, in many ways, inconsistent. The differences in study conclusions might result from the different methods used to detect SDF, the study design and the inclusion criteria. Consequently, it is difficult to decide whether SDF testing should be carried out in fertility assessment and ART. It is clear that there is an urgent need for the standardisation of the methods and for additional clinical studies on the impact of SDF on ART outcomes.

Sperm DNA fragmentation and oxidation are independent of malondialdheyde

BACKGROUND

There is clinical evidence to show that sperm DNA damage could be a marker of sperm quality and extensive data exist on the relationship between DNA damage and male fertility status. Detecting such damage in sperm could provide new elements besides semen parameters in diagnosing male infertility. We aimed to assess sperm DNA fragmentation and oxidation and to study the association between these two markers, routine semen parameters and malondialdehyde formation.

METHODS

Semen samples from 55 men attending the Histology-Embryology Laboratory of Sfax Faculty of Medicine, Tunisia, for semen investigations were analysed for sperm DNA fragmentation and oxidation using flow cytometry. The Sperm was also assessed spectrophotometrically for malondialdehyde formation.

RESULTS

Within the studied group, 21 patients were nonasthenozoospermic (sperm motility ≥ 50%) and 34 patients were considered asthenozoospermic (sperm motility < 50%). A positive correlation was found between sperm DNA fragmentation and oxidation (p = 0.01; r = 0.33). We also found a negative correlation between sperm DNA fragmentation and some sperm parameters: total motility (p = 0.001; r = -0.43), rapid progressive motility (type a motility) (p = 0.04; r = -0.27), slow progressive motility (type b motility) (p = 0.03; r = -0.28), and vitality (p < 0.001; r = -0.65). Sperm DNA fragmentation was positively correlated with coiled tail (p = 0.01; r = 0.34). The two parameters that were found to be correlated with oxidative DNA damage were leucocytes concentrations (p = 0.01; r = 0.38) and broken neck (p = 0.02; r = 0.29). Sperm MDA levels were negatively correlated with sperm concentration (p < 0.001; r = -0.57), total motility (p = 0.01; r = -0.35) and type a motility (p = 0.03; r = -0.32); but not correlated with DNA fragmentation and DNA oxidation.

CONCLUSIONS

Our results support the evidence that oxidative stress plays a key role in inducing DNA damage; but nuclear alterations and malondialdehyde don't seem to be synchronous.

The determination of oxidative damage in heart tissue of rats caused by ruthenium(II) and gold(I) N-heterocyclic carbene complexes

In the present study, we aimed to determine the oxidative damage in rat heart tissue induced by ruthenium(II)-NHC (Ru) and gold(I)-NHC (Au) complexes which have anticarcinogenic effects and not used clinically yet. For this purpose, 35 Sprague-Dawley rats were randomly divided into 5 equal groups. In the control group, rats treated with saline, Ru and Au complexes were intraperitoneally given high (10 mg/kg) and low (5 mg/kg) doses as only one administration. The animals were killed, and heart tissues were taken on day 10 of the drug administration for the determination of the biochemical parameters (malondialdehyde, superoxide dismutase, reduced glutathione and catalase levels). It was determined that both Ru and Au complexes treatment significantly caused oxidative damage compared to the control group. Additionally, it was shown that Au treatment caused more adverse effects than Ru treatment. Also, it was clearly found that the occurred effects were generally determined in a dose-dependent manner. In conclusion, when these compounds synthesized for the treatment of cancer were used, they caused oxidative damage in heart tissue. However, Ru complex could be preferred for cancer treatment in terms of user safety.

DNA damage and repair in human oocytes and embryos: a review

The genome of all cells is protected at all times by mechanisms collectively known as DNA repair activity (DRA). Such activity is particularly important at the beginning of human life, i.e. at fertilization, immediately after and at the very onset of embryonic development. DRA in early development is, by definition, of maternal origin: the transcripts stored during maturation, need to control the integrity of chromatin, at least until the maternal/zygotic transition at the 4- to 8-cell stage in the human embryo. Tolerance towards DNA damage must be low during this critical stage of development. The majority of DNA damage is due to either apoptosis or reactive oxygen species (ROS). Apoptosis, abortive or not, is a common feature in human sperm, especially in oligoasthenospermic patients and FAS ligand has been reported on the surface of human spermatozoa. The susceptibility of human sperm to DNA damage is well documented, particularly the negative effect of ROS (Kodama et al., 1997; Lopes et al., 1998a, b) and DNA modifying agents (Zenzes et al., 1999; Badouard et al., 2007). DNA damage in sperm is one of the major causes of male infertility and is of much concern in relation to the paternal transmission of mutations and cancer (Zenzes, 2000; Aitken et al., 2003; Fernández-Gonzalez, 2008). It is now clear that DNA damaged spermatozoa are able to reach the fertilization site in vivo (Zenzes et al., 1999), fertilize oocytes and generate early embryos both in vivo and in vitro. The effect of ROS on human oocytes is not as easy to study or quantify. It is a common consensus that the maternal genome is relatively well protected while in the maturing follicle; however damage may occur during the long quiescent period before meiotic re-activation (Zenzes et al., 1998). In fact, during the final stages of follicular growth, the oocyte may be susceptible to damage by ROS. With regards to the embryo there is active protection against ROS in the surrounding environment i.e. in follicular and tubal fluid (El Mouatassim et al., 2000; Guerin et al., 2001). DNA repair activity in the zygote is mandatory in order to avoid mutation in the germ line (Derijck et al., 2008). In this review we focus on the expression of mRNAs that regulate DNA repair capacity in the human oocyte and the mechanisms that protect the embryo against de novo damage.