Sperm head defects and disturbances in spermatozoal chromatin and DNA integrities in idiopathic infertile subjects: Association with cigarette smoking

Metabolic characterization of human sperm cells using the Seahorse metabolic flux analyzer

BACKGROUND

The concerning trend on male infertility global prevalence, together with the unexplainable causes in half of those cases, highlights that there are still aspects of this disease to be understood and solved. To address this issue, one should not only be aware of the limitations of the implemented diagnostic tools, but also understand the sperm cell in depth, structurally, biochemically, molecularly in order to develop reliable and ready-to-be new/improved diagnostic tools. In this sense, the sperm cells metabolism, highly related to its functionality, seems to be a promising aspect to explore. Though there is much information on the human sperm metabolism, there is still a lack of a quick integrated and comprehensive analysis that may be introduced with the potential to reveal innovative clinically relevant information.

OBJECTIVES

Find metabolic details on human sperm that can be accessed easily, in real time and using few cells, relying on the bivalent potential of the Seahorse flux analyzer (SFA).

RESULTS

We have obtained standard records on human sperm cells' oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), that together with the metabolic metrics provided information on sperm cells' oxidative and glycolytic metabolism. Furthermore, a metabolic interindividual variation was observed.

DISCUSSION AND CONCLUSION

Although the comparison with other species or cell types is not linear and warrant further studies, the metabolic profile of human sperm cells seems to be similar to that of other species. Altogether our results corroborate the value of SFA for metabolic human sperm cell analysis, warranting new studies, and anticipating several applications in the male infertility field.

Smoking Induces a Decline in Semen Quality and the Activation of Stress Response Pathways in Sperm

Male infertility is a prevalent concern affecting couples worldwide. While genetic factors, hormonal imbalances, and reproductive system defects play significant roles, emerging evidence suggests that lifestyle choices also profoundly impact male fertility. This study aimed to explore the effects of several lifestyle factors, including tobacco and alcohol consumption, physical activity, and dietary habits, on semen quality parameters and molecular biomarkers. Thirty healthy male volunteers were recruited in the Urology service at Hospital Infante D. Pedro, Aveiro, Portugal. Participants completed lifestyle questionnaires and provided semen samples, which were analyzed according to the World Health Organization criteria by experienced technicians. We also analyzed the expression levels of antioxidant enzymes and heat-shock response-related proteins to explore the activation of signaling pathways involved in stress response within sperm cells. Our results revealed that tobacco consumption reduced semen volume and total sperm count. Although the changes in the percentage of total motility and normal morphology in the smokers' group did not reach statistical significance, a slight decrease was observed. Moreover, we identified for the first time a significant association between tobacco consumption and increased levels of heat shock protein 27 (HSP27) and phosphorylated HSP27 (p-HSP27) in sperm cells, indicating the potential detrimental effects of tobacco on the reproductive system. This study highlights that lifestyle factors reduce semen quality, possibly by inducing stress in sperm, raising awareness about the effects of these risk factors among populations at risk of male infertility.

Smoking and Its Consequences on Male and Female Reproductive Health

Smoking contributes to the death of around one in 10 adults worldwide. Specifically, cigarettes are known to contain around 4000 toxins and chemicals that are hazardous in nature. The negative effects of smoking on human health and interest in smoking-related diseases have a long history. Among these concerns are the harmful effects of smoking on reproductive health. Thirteen percent of female infertility is due to smoking. Female smoking can lead to gamete mutagenesis, early loss of reproductive function, and thus advance the time to menopause. It has been also associated with ectopic pregnancy and spontaneous abortion. Even when it comes to assisted reproductive technologies cycles, smokers require more cycles, almost double the number of cycles needed to conceive as non-smokers. Male smoking is shown to be correlated with poorer semen parameters and sperm DNA fragmentation. Not only active smokers but also passive smokers, when excessively exposed to smoking, can have reproductive problems comparable to those seen in smokers. In this book chapter, we will approach the effect of tobacco, especially tobacco smoking, on male and female reproductive health. This aims to take a preventive approach to infertility by discouraging smoking and helping to eliminate exposure to tobacco smoke in both women and men.

Sperm concentration and semen volume increase after smoking cessation in infertile men

Smoking has negative reproductive consequences. This study investigated the effect of smoking cessation on the main semen parameters. We included 90 participants who applied to our infertility clinic and smoked at least 20 cigarettes a day for at least 1 year. Of the 90 participants, 48 were in the study group and 42 were in the control group. Semen analysis was performed before and at least 3 months after quitting smoking in the study group. Semen analysis was repeated at baseline and at least 3 months later in the control group. Semen parameters such as volume, sperm concentration, total sperm count, morphology, and motility were evaluated according to the World Health Organization criteria. Patient characteristics as well as the duration of the smoking period, the number of cigarettes smoked per day and the time elapsed since smoking cessation were recorded. The mean age of the participants was 34.69 ± 5.3 years, and the duration of infertility was 34.12 ± 12.1 months (n = 90). The number of cigarettes smoked per day was 30.14 ± 6.69, and the smoking time was 8.31 ± 3.53 years. The average time to quit smoking was 104.2 ± 11.51 days (n = 48). A significant increase in semen volume, sperm concentration and total sperm count was observed 3 months after smoking cessation (2.48 ± 0.79 ml vs. 2.90 ± 0.77 ml, p = 0.002; 18.45 × 10⁶/ml ± 8.56 vs. 22.64 × 10⁶/ml ± 11.69, p = 0.001; 45.04 ± 24.38 × 10⁶ vs. 65.1 ± 34.9 × 10⁶, p < 0.001, respectively). This study showed that smoking cessation had a positive effect on sperm concentration, semen volume, and total sperm count. Although smoking cessation contributed positively to sperm motility and morphology, the difference was not statistically significant.

Impact of heavy alcohol consumption and cigarette smoking on sperm DNA integrity

The purposes of the presents study were to investigate the impact of alcohol consumption and cigarette smoking on semen parameters and sperm DNA quality, as well as to determine whether tobacco smoking, or alcohol consumption causes more deterioration of sperm quality. Two hundred and eleven semen samples of men were included in this study. Four groups were studied: heavy smokers (N = 48), heavy drinkers (N = 52), non-smokers (n = 70), and non-drinkers (n = 41). Semen parameters were determined according to WHO guidelines, protamine deficiency assessed by chromomycin (CMA3) staining, and sperm DNA fragmentation (sDF) evaluated by TUNEL assay. Sperm parameters were significantly higher in non-smokers versus smokers and in non-drinkers versus drinkers (p < 0.005). However, protamine deficiency and sDF were significantly lower in non-smokers versus smokers and in non-drinkers versus drinkers (p < 0.0001). No significant difference in the semen analysis parameters was observed between heavy smokers and heavy drinkers (semen volume: 3.20 ± 1.43 vs. 2.81 ± 1.56 ml, semen count: 65.75 ± 31.32 vs. 53.51 ± 32.67 mill/ml, total motility: 24.27 ± 8.18 vs. 23.75 ± 1.75%, sperm vitality: 36.15 ± 18.57 vs. 34.62 ± 16.65%, functional integrity: 41.56 ± 18.57 vs. 45.96 ± 17.98% and the morphologically normal spermatozoa: 28.77 ± 11.82 vs. 27.06 ± 13.13%, respectively). However, protamine deficiency was significantly higher among drinkers than smokers (37.03 ± 9.75 vs. 33.27 ± 8.56%, p = 0.020). The sDF was also significantly higher among drinkers than smokers (22.37 ± 7.60 vs. 15.55 ± 3.33%, p < 0.0001). Thus, cigarette smoking, and heavy alcohol intake can deteriorate sperm quality. However, alcohol consumption deteriorates sperm maturity and damages DNA integrity at significantly higher rates than cigarette smoking.

Alleviation of nicotine-induced reproductive disorder, clastogenicity, and histopathological alterations by fenugreek saponin bulk and nanoparticles in male rats

Nicotine is the most abundant ingredient in cigarette smoking and has serious side effects on the lung, heart, reproductive system, and many other human organs. Saponins extracted from many plants exhibit multiple biological actions such as anti-cancer effects. Therefore, the possible protective effect of fenugreek saponin (FS) and nanofenugreek saponin (NFS) against nicotine-induced toxicity in male rats was investigated in this study. Animals were divided into a control group and the nicotine (1.5 mg/kg/day), FS (25, 50, and 100 mg/kg/day), or/and NFS (20, 40, and 80 mg/kg/day) administered groups. Micronucleus assay, histopathological, and sperm abnormality examinations as well as measurement of the acetylcholinesterase (AChE) gene expression were conducted. Our findings revealed that nicotine treatment induced significant increases in the incidence of micronucleus, sperm abnormalities, and expression levels of AChE in addition to inducing histopathological changes in rat testis. On the other hand, administration of FS or NFS with nicotine significantly decreased the incidence of micronuclei and the percentage of sperm abnormalities as well as the expression levels of AChE gene. Moreover, nicotine-induced histological alterations were reduced by given FS or NFS with nicotine. In conclusion, nicotine-induced sperm abnormalities, chromosomal damage, and histological injuries were mitigated by administration of FS or NFS with nicotine, and thus, FS and NFS could be used as ameliorating agents against nicotine toxicity.

Exposure to polycyclic aromatic hydrocarbons and nicotine, and associations with sperm DNA fragmentation

Background

Tobacco smoking has been reported to cause DNA fragmentation and has been suggested to cause mutations in spermatozoa. These effects have been ascribed to the action of polycyclic aromatic hydrocarbons (PAH) present in the smoke. Simultaneously, DNA fragmentation has been associated with mutagenesis.

Objective

The aim of this study was to investigate whether levels of urinary biomarkers of PAH and nicotine exposure were associated with sperm DNA fragmentation.

Methods

In the urine of 381 men recruited from two cohorts of young men (17–21 years old) from the general Swedish population, the PAH metabolites 1‐hydroxypyrene and 2‐hydroxyphenanthrene, as well as the nicotine metabolite cotinine, were measured. The sperm DNA fragmentation index (DFI) was analysed using the sperm chromatin structure assay. Associations between the DFI, and PAH metabolite levels as continuous variables as well as in quartiles, were studied by general linear models adjusted for abstinence time. A similar analysis was carried out for cotinine levels, according to which the men were categorised as “non‐smoking” (n = 216) and “smoking” (n = 165).

Results

No association was found between levels of any of the three biomarkers and DFI, either as a continuous variable (p = 0.87–0.99), or when comparing the lowest and the highest quartiles (p = 0.11–0.61). The same was true for comparison of men categorised as non‐smoking or smoking (DFI 11.1% vs. 11.8%, p = 0.31).

Discussion

We found no evidence of PAH or nicotine exposure to be associated with DFI, which does not exclude that these exposures may have other effects on sperm DNA.

Conclusion

In these young men, levels of biomarkers of nicotine and PAH exposure were not associated with DFI.

Oxidative stress and DNA damage status in couples undergoing in vitro fertilization treatment

This study examined the status of oxidative stress in 599 couples undertaking in vitro fertilization (IVF) treatment and its association with reproductive hormones, smoking, and outcomes. Oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide (H₂O₂), catalase (CAT), and total antioxidant capacity (TAC) were determined in follicular fluid and seminal plasma. Tail moment (TM) was used to evaluate DNA damage in the sperm and granulosa cells. Reproductive hormones in serum and cotinine (COT) in urine, follicular fluid, and seminal plasma samples were determined. Separate multivariate linear regression was used to assess associations between levels of each oxidative stress biomarker and each hormone and smoking parameter (modeled as natural log-transformed). The findings indicate that some oxidative stress and DNA damage biomarkers played a role in disrupting certain reproductive hormones in women and their male partners either by overproducing reactive oxygen species or reducing antioxidant defense capacity. Although women were nonsmokers, COT levels > 50 and 10 µg/L in urine and follicular were observed in 5.7 and 1.7%, respectively. Levels of follicular fluid COT were positively associated with H₂O₂ and TM. We used log-binomial multivariate regression to estimate relative risks for the association between oxidative stress/DNA damage and IVF binary outcomes (fertilization rate > 50%, biochemical pregnancy, clinical pregnancy, and live birth). An increase in the CAT levels of follicular fluid was associated with a 48 and 41% decrease in the risk of poor fertilization rate (≤50%) and unsuccessful live birth, respectively. After the models were adjusted for hormonal factors, the associations remained the same, except that the elevated TAC in follicular fluid became significantly associated with a decrease of 42% in the risk of poor fertilization rate (≤50%). The higher antioxidant activity (CAT and TAC) in follicular fluid might positively impact specific IVF outcomes.

Influence of Risk Factors for Male Infertility on Sperm Protein Composition

Male infertility is a common health problem that can be influenced by a host of lifestyle risk factors such as environment, nutrition, smoking, stress, and endocrine disruptors. These effects have been largely demonstrated on sperm parameters (e.g., motility, numeration, vitality, DNA integrity). In addition, several studies showed the deregulation of sperm proteins in relation to some of these factors. This review inventories the literature related to the identification of sperm proteins showing abundance variations in response to the four risk factors for male infertility that are the most investigated in this context: obesity, diabetes, tobacco smoking, and exposure to bisphenol-A (BPA). First, we provide an overview of the techniques used to identify deregulated proteins. Then, we summarise the main results obtained in the different studies and provide a compiled list of deregulated proteins in relation to each risk factor. Gene ontology analysis of these deregulated proteins shows that oxidative stress and immune and inflammatory responses are common mechanisms involved in sperm alterations encountered in relation to the risk factors.

The factors affecting male infertility: A systematic review

Background

In recent years, the incidence of male infertility has increased worldwide. It is necessary to study the factors that influence male infertility in each area/region for better management.

Objective

To determine the factors affecting male infertility in the Iranian male population.

Materials and Methods

An online search was conducted in electronic databases including PubMed, Google Scholar, SID, and Scopus to identify articles on the factors associated with male infertility, published in English and Persian. The keywords used to perform the search included "factor", "epidemiology", "causes of infertility", and "male infertility". The search was conducted without a time restriction, up to April 2020.

Results

The search resulted in a total number of 691 studies. After an assessment of the articles, finally 14 studies were included in this study with a total number of 26,324 infertile males. The factors associated with male infertility included semen abnormalities, varicocele and testis disorder, smoking, exposure to heat, obesity, anabolic steroids, vascular abnormalities, anti-spermatogenesis factors, antidepressants, taking ranitidine and cimetidine, penile discharge and genital ulcers, painful micturition, occupational factors, alcohol, chronic disease, sexual disorder, Surgical and urological diseases, genetic factors and herpes infection. Among these, the semen and varicocele disorders were common in most studies.

Conclusion

The present review suggests that the factors affecting male infertility in Iran are similar to those reported from other countries. The results of this study can be used in adopting appropriate strategies for infertility management in Iran.

Organophosphorus pesticide quinalphos (Ekalux 25 E.C.) reduces sperm functional competence and decreases the fertilisation potential in Swiss albino mice

Quinalphos (QP) is one of the most commonly used organophosphate pesticide for agriculture. In this study, adult Swiss albino male mice were orally administered with 0.25, 0.5 and 1.0 mg/kg of QP (Ekalux 25 E.C.) for ten consecutive days and the reproductive function was assessed at 35 and 70 days after QP treatment. At highest dose (1.0 mg/kg), QP exposure resulted in significant decrease in motility and increase in sperm head defects and DNA damage. Pharmacokinetic data showed a threefold increase in concentration of QP in the testis as compared to serum. QP was detectable in testes even after 24 hr of administration indicating slow clearance from tissue. In addition, high oestradiol, low testosterone level with a parallel increase in aromatase and cytochrome P450 transcript levels was observed. Significant decrease in fertilisation, lower blastocyst rate and poor blastocyst quality was observed when spermatozoa collected from QP exposed mice were subjected to in vitro fertilisation. In conclusion, exposure of QP to male mice decreases the sperm functional competence and fertilising ability, which appears to be mediated through elevated oxidative stress and altered steroidogenesis in testes.

Oxidative stress and male infertility

BACKGROUND

Between 30% and 80% of patients with male infertility produce excessive reactive oxygen species (ROS) in their ejaculate even though the cause of male infertility is unexplained in approximately half of cases. The strong connection between oxidative stress (OS) and male infertility has led recent investigators to propose the term "Male Oxidative Stress Infertility (MOSI)" to describe OS-associated male infertility.

METHODS

We searched the PubMed database for original and review articles to survey the effects of OS on male infertility, and then verified the effects and treatments.

MAIN FINDINGS

Seminal plasma contains many antioxidants that protect sperm from ROS, because low amounts of ROS are required in the physiological fertilization process. The production of excessive ROS causes OS which can lower fertility through lipid peroxidation, sperm DNA damage, and apoptosis. Several assays are available for evaluating OS, including the MiOXSYS® analyzer to measure oxidation-reduction potential. Several measures should be considered for minimizing OS and improving clinical outcomes.

CONCLUSION

Accurately diagnosing patients with MOSI and identifying highly sensitive biomarkers through proteomics technology is vital for better clinical outcomes.

Personalized Medicine for the Infertile Male

Personalized medicine uses a patient's genotype, environment, and lifestyle choices to create a tailored diagnosis and therapy plan, with the goal of minimizing side effects, avoiding lost time with ineffective treatments, and guiding preventative strategies. Although most precision medicine strategies are still within the laboratory phase of development, this article reviews the promising technologies with the greatest potential to improve the diagnosis and treatment options for male infertility, including sperm cell transplantation, genomic editing, and new biomarker assays, based on the latest proteomic and epigenomic studies.

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.

Effect of hookah (water pipe) smoking on semen parameters

Hookah (water pipe) smoking, an old method of tobacco smoking, is regaining widespread popularity all over the world. Although the research in this field is still deficient, it has been proven for its harmful effect on human's health by increasing the risk of cardiovascular disease, infection and lung, oral and bladder cancer (Al-Numair et al., J Food Agric Environ, 5: 17, 2007; Bou Fakhreddine et al., Respir Med, 108: 1241-1253, 2014; Chaouachi, J Negat Results Biomed, 5: 17, 2006). However, no research was found to address its effect on human fertility or reproductive outcome. In this cross-sectional study, we aim to explore the effect of smoking hookah on human semen parameters among men attending In Vitro Fertilization LABs for seminal fluid analysis testing. 104 patients aged between 25 and 45, who are noncigarette smokers and have no chronic medical illness, were enrolled in the study: 50 hookah nonsmokers and 54 hookah smokers. Their semen parameters were compared. Semen volume, normal morphology and progressive motility were slightly lower in the hookah smoker (3.21 ml; 10.2%; 29.56%) versus (3.45 ml; 11.5%; 33.20%), respectively, in nonhookah smokers; however, the difference was not statistically significant. The effect of hookah smoking on semen observed in our study was not statistically significant. Further studies are needed to explore more and confirm any unfavourable effect.

Assessment of the toxicity effects of nicotine on sperm and IVF and the potential protective role of silymarin—an experimental study in mice

Background

Male infertility is usually caused via the inability to produce adequate quantities of healthy and active sperms. Nicotine (NIC) is an alkaloid organic compound, predominantly found in the leaves of the tobacco plant. The major part of the nicotine is not ionized, so it can easily pass through cell membranes. Meanwhile, most of the disorders are caused by oxidative stress due to oxygen free radicals and other reactive species. Antioxidant supplements and antioxidant-rich foods can reduce induced oxidative stress without becoming destabilized themselves. This study aimed to examine spermato-protective potential of silymarin (SIL), on sperm and in vitro fertility (IVF) rate in nicotine-treated mice.

Results

Our results show a significant increase in the number of abnormal sperm morphology after nicotine exposure, when compared to control groups (p < 0.05). On the other hand, SIL had a significant effect on the sperm count at each of the treated doses. Further, in the mice that received nicotine plus silymarin, the viable sperm percentage and the progressive sperm motility were significant (p < 0.05). Also, a significant reduction in the number of two-cell embryos and blastocyst-derived embryo was seen with increment in the number of dead embryos in mice receiving nicotine alone (p < 0.05).

Conclusions

In conclusion, SIL could support prevention of the adverse reproductive effects of nicotine. Moreover, SIL200 mg/kg may be therefore considered as a spermato-protective agent in dietary and herbal supplements.

Cannabis consumption might exert deleterious effects on sperm nuclear quality in infertile men

RESEARCH QUESTION

Can cannabis consumption alter sperm nuclear integrity in infertile men?

DESIGN

A retrospective cross-sectional study conducted between July 2003 and December 2013, which included 54 men who consulted for male-factor infertility. Twenty-seven infertile men who were regular cannabis users were matched to 27 infertile men who were cannabis non-users. To complement the conventional semen parameter and plasma hormone level assessments, sperm nuclear alterations were explored using fluorescence in-situ hybridization to assess numerical chromosomal abnormalities, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling to investigate DNA fragmentation, aniline blue staining to examine chromatin condensation and a motile sperm organelle morphology examination to detect vacuoles in sperm heads.

RESULTS

The rates of sperm aneuploidy (P = 0.0044), diploidy (P = 0.037), total chromosome abnormalities (P = 0.0027) and DNA fragmentation (P = 0.027) were significantly higher in cannabis users than in non-cannabis users.

CONCLUSIONS

Cannabis consumption might have deleterious effects on sperm nuclear quality in infertile men by increasing numerical chromosome abnormalities and DNA fragmentation. Cannabis consumption induces these detrimental effects on the progression of spermatogenesis from meiotic stages to spermiogenesis and potentially on post-testicular sperm maturation in infertile men. Any potential findings, however, need to be validated with larger sample size, and our data are only exploratory findings.

Tobacco smoking and semen quality in infertile males: a systematic review and meta-analysis

BACKGROUND

Nowadays, the total number of couples visiting an infertility clinic is on the rise. Tobacco smoking is considered one of the major factors leading to male infertility. In this study, we aimed to systematically investigate the impact of tobacco smoking on semen quality in infertile male participants.

METHODS

Online databases (Cochrane Central database of Randomized Controlled Trials and the databases of MEDLINE and EMBASE respectively) were searched for relevant English publications that satisfied the inclusion and exclusion criteria of this analysis. The clinical endpoints which were assessed included semen parameters (oligozoospermia, asthenozoospermia, teratozoospermia, and azoospermia), morphological defects of spermatozoa and the hormones involved in reproduction. RevMan 5.3 software was used to analyze the data whereby mean difference (MD) and risk ratios (RR) with 95% confidence intervals (CI) were generated to represent the results.

RESULTS

Sixteen studies with a total number of 10,823 infertile male participants (5257 smokers and 5566 non-smokers) were included. Results of this analysis showed oligozoospermia to be significantly higher in smokers (RR: 1.29, 95% CI: 1.05-1.59; P = 0.02). Morphological defect of spermatozoa (MD: 2.44, 95% CI: 0.99-3.89; P = 0.001) was also significantly higher in smokers whereby significant head (MD: 1.76, 95% CI: 0.32-3.20; P = 0.02), neck (MD: 1.97, 95% CI: 0.75-3.18; P = 0.002) and tail (MD: 1.29, 95% CI: 0.35-2.22; P = 0.007) defects were observed. However, smoking did not affected the pH (MD: 0.04, 95% CI: [- 0.03-0.11]; P = 0.30) and motility (RR: 1.42, 95% CI: 0.97-2.09; P = 0.07) of spermatozoa. Additionally, tobacco smoking did not cause any dis-balance in hormones which were involved in reproduction.

CONCLUSIONS

In conclusion, with reference to the clinical endpoints which were studied in this analysis, tobacco smoking was associated with a lower sperm count and an increase in the number of morphological defects of spermatozoa. However, the pH and motility of spermatozoa as well as the production of hormones which were involved in reproduction were not affected in this population of infertile males.

Is male infertility associated with increased oxidative stress in seminal plasma? A-meta analysis

Objectives

We conducted a systematic review and meta-analysis of observational case-control studies to evaluate markers of oxidative stress in seminal plasma of patients with male infertility.

Background

Current evidence links oxidative stress to male infertility, in which multiple markers of oxidative stress have been widely detected, publishing inconsistent results with regard to the role of oxidative stress markers in the evaluation of male infertility. Therefore, a systematic review and meta-analysis on this issue is necessary.

Results

From the 1024 articles initially retrieved, 65 studies were included in our meta-analysis with 11 oxidative stress markers, containing 3819 male infertility patients and 2012 controls. The concentrations of malondialdehyde (SMD = 1.86, p < 0.00001), NO (SMD = 0.89, p = 0.001), carbonyl protein (SMD = 2.09, p < 0.00001) in seminal plasma were significantly higher in infertility patients. The concentrations of GSH (SMD = -1.68, p < 0.00001), vitamin C (SMD = -1.12, p < 0.00001), and vitamin E (SMD = -1.48, p = 0.003), as well as the activities of catalase (SMD = -1.91, p < 0.0001), glutathione peroxidase (SMD = -1.96, p = 0.0002) and glutathione-S-transferase (SMD = -1.62, p = 0.009) declined remarkably, resulting in decreased total antioxidant capacity (SMD = -1.77, p < 0.00001). Besides, the activity of superoxide dismutase showed no statistical difference between infertility patients and controls (SMD = -0.51, p = 0.07).

Conclusions

Our meta-analysis suggests that oxidative stress in seminal plasma resulting from decreased antioxidant defense are associated with male infertility.

Methods

Using PubMed, EMBASE, CNKI, VIP, and Wanfang database, we searched for literature reporting the detection of oxidative stress markers in the seminal plasma of male infertility published up to June 2017. Standardized mean differences (SMDs) and 95% confidence intervals (95%CI) were calculated for the finally analysis.

Father's environment before conception and asthma risk in his children: a multi-generation analysis of the Respiratory Health In Northern Europe study

Background

Whereas it is generally accepted that maternal environment plays a key role in child health, emerging evidence suggests that paternal environment before conception also impacts child health. We aimed to investigate the association between children's asthma risk and parental smoking and welding exposures prior to conception.

Methods

In a longitudinal, multi-country study, parents of 24 168 offspring aged 2-51 years provided information on their life-course smoking habits, occupational exposure to welding and metal fumes, and offspring's asthma before/after age 10 years and hay fever. Logistic regressions investigated the relevant associations controlled for age, study centre, parental characteristics (age, asthma, education) and clustering by family.

Results

Non-allergic early-onset asthma (asthma without hay fever, present in 5.8%) was more common in the offspring with fathers who smoked before conception {odds ratio [OR] = 1.68 [95% confidence interval (CI) = 1.18-2.41]}, whereas mothers' smoking before conception did not predict offspring asthma. The risk was highest if father started smoking before age 15 years [3.24 (1.67-6.27)], even if he stopped more than 5 years before conception [2.68 (1.17-6.13)]. Fathers' pre-conception welding was independently associated with non-allergic asthma in his offspring [1.80 (1.29-2.50)]. There was no effect if the father started welding or smoking after birth. The associations were consistent across countries.

Conclusions

Environmental exposures in young men appear to influence the respiratory health of their offspring born many years later. Influences during susceptible stages of spermatocyte development might be important and needs further investigation in humans. We hypothesize that protecting young men from harmful exposures may lead to improved respiratory health in future generations.

Fatherhood and Sperm DNA Damage in Testicular Cancer Patients

Testicular cancer (TC) is one of the most treatable of all malignancies and the management of the quality of life of these patients is increasingly important, especially with regard to their sexuality and fertility. Survivors must overcome anxiety and fears about reduced fertility and possible pregnancy-related risks as well as health effects in offspring. There is thus a growing awareness of the need for reproductive counseling of cancer survivors. Studies found a high level of sperm DNA damage in TC patients in comparison with healthy, fertile controls, but no significant difference between these patients and infertile patients. Sperm DNA alterations due to cancer treatment persist from 2 to 5 years after the end of the treatment and may be influenced by both the type of therapy and the stage of the disease. Population studies reported a slightly reduced overall fertility of TC survivors and a more frequent use of ART than the general population, with a success rate of around 50%. Paternity after a diagnosis of cancer is an important issue and reproductive potential is becoming a major quality of life factor. Sperm chromatin instability associated with genome instability is the most important reproductive side effect related to the malignancy or its treatment. Studies investigating the magnitude of this damage could have a considerable translational importance in the management of cancer patients, as they could identify the time needed for the germ cell line to repair nuclear damage and thus produce gametes with a reduced risk for the offspring.

Impact of alcohol and cigarette smoking consumption in male fertility potential: Looks at lipid peroxidation, enzymatic antioxidant activities and sperm DNA damage

Alcohol intake and cigarette smoking are the major lifestyle factors with negative impact on fertility. We were interested to evaluate the negative impact of these factors on oxidative stress (OS), enzymatic antioxidant activity (EAO) of spermatozoa and on its DNA damage. This study included 108 male infertile patients with normal range of sperm conventional parameters but with unexplained infertility in assisted reproductive technologies programme. Firstly, OS was analysed based on lipid peroxidation (MDA) and EAO which included catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR). Secondly, we evaluated DNA fragmentation by TUNEL assay and chromatin decondensation by aniline blue colouration. The whole lot was divided into four groups: control (nonalcoholic and nonsmoker patients), alcohol group, smoking group and alcohol-smoking group. The results showed, in three last groups compared to control an increased CAT, SOD and GR activities with high MDA level especially in smoking and alcohol-smoking group. The latter showed the highest values of DNA fragmentation and chromatin decondensation (31% and 39%) to exceed DNA damage normal range. Indeed, smoking and alcohol intake lead to increase EAO due to long-term unbalanced antioxidant/oxidation ratio with high OS which cause consequently sperm DNA damage calling in need by urgency to change the lifestyle behaviour.

The Society for Translational Medicine: clinical practice guidelines for sperm DNA fragmentation testing in male infertility

Sperm DNA fragmentation (SDF) testing has been emerging as a valuable tool for male fertility evaluation. While the essential role of sperm DNA integrity in human reproduction was extensively studied, the clinical indication of SDF testing is less clear. This clinical practice guideline provides recommendations of clinical utility of the test supported by evidence. It is intended to serve as a reference for fertility specialists in identifying the circumstances in which SDF testing should be of greatest clinical value. SDF testing is recommended in patients with clinical varicocele and borderline to normal semen parameters as it can better select varicocelectomy candidates. Outcomes of natural pregnancy and assisted reproductive techniques (ART) can be predicted by result of SDF tests. High SDF is also linked with recurrent pregnancy loss (RPL) and failure of ART. Result of SDF testing may change the management decision by selecting the most appropriate ART with the highest success rate for infertile couples. Several studies have demonstrated the benefit in using testicular instead of ejaculated sperm in men with high SDF, oligozoospermia or recurrent in vitro fertilization (IVF) failure. Infertile men with modifiable lifestyle factor may benefit from SDF testing by reinforcing risk factor modification and monitoring patient's progress to intervention.

From sperm to offspring: Assessing the heritable genetic consequences of paternal smoking and potential public health impacts

Individuals who smoke generally do so with the knowledge of potential consequences to their own health. What is rarely considered are the effects of smoking on their future children. The objective of this work was to review the scientific literature on the effects of paternal smoking on sperm and assess the consequences to offspring. A literature search identified over 200 studies with relevant data in humans and animal models. The available data were reviewed to assess the weight of evidence that tobacco smoke is a human germ cell mutagen and estimate effect sizes. These results were used to model the potential increase in genetic disease burden in offspring caused by paternal smoking, with specific focus on aneuploid syndromes and intellectual disability, and the socioeconomic impacts of such an effect. The review revealed strong evidence that tobacco smoking is associated with impaired male fertility, and increases in DNA damage, aneuploidies, and mutations in sperm. Studies support that these effects are heritable and adversely impact the offspring. Our model estimates that, with even a modest 25% increase in sperm mutation frequency caused by smoke-exposure, for each generation across the global population there will be millions of smoking-induced de novo mutations transmitted from fathers to offspring. Furthermore, paternal smoking is estimated to contribute to 1.3 million extra cases of aneuploid pregnancies per generation. Thus, the available evidence makes a compelling case that tobacco smoke is a human germ cell mutagen with serious public health and socio-economic implications. Increased public education should be encouraged to promote abstinence from smoking, well in advance of reproduction, to minimize the transmission of harmful mutations to the next-generation.

Clinical utility of sperm DNA fragmentation testing: practice recommendations based on clinical scenarios

Sperm DNA fragmentation (SDF) has been generally acknowledged as a valuable tool for male fertility evaluation. While its detrimental implications on sperm function were extensively investigated, little is known about the actual indications for performing SDF analysis. This review delivers practice based recommendations on commonly encountered scenarios in the clinic. An illustrative description of the different SDF measurement techniques is presented. SDF testing is recommended in patients with clinical varicocele and borderline to normal semen parameters as it can better select varicocelectomy candidates. High SDF is also linked with recurrent spontaneous abortion (RSA) and can influence outcomes of different assisted reproductive techniques. Several studies have shown some benefit in using testicular sperm rather than ejaculated sperm in men with high SDF, oligozoospermia or recurrent in vitro fertilization (IVF) failure. Infertile men with evidence of exposure to pollutants can benefit from sperm DNA testing as it can help reinforce the importance of lifestyle modification (e.g., cessation of cigarette smoking, antioxidant therapy), predict fertility and monitor the patient’s response to intervention.

Kinetic modeling of nicotine in mainstream cigarette smoking

BACKGROUND

The attempt to understand the kinetic behavior of nicotine in tobacco will provide a basis for unraveling its energetics in tobacco burning and the formation of free radicals considered harmful to the cigarette smoking community. To the best of our knowledge, the high temperature destruction kinetic characteristics of nicotine have not been investigated before; hence this study is necessary especially at a time addiction science and tobacco research in general is gaining intense attention.

METHODS

The pyrolysis of tobacco under conditions simulating cigarette smoking in the temperature region 200-700 °C has been investigated for the evolution of nicotine and pyridine from two commercial cigarettes coded ES1 and SM1 using gas chromatography hyphenated to a mass selective detector (MSD). Moreover, a kinetic model on the thermal destruction of nicotine within a temperature window of 673 and 973 K is proposed using pseudo-first order reaction kinetics. A reaction time of 2.0 s was employed in line with the average puff time in cigarette smoking. Nonetheless, various reaction times were considered for the formation kinetics of nicotine.

RESULTS

GC-MS results showed the amount of nicotine evolved decreased with increase in the puff time. This observation was remarkably consistent with UV-Vis data reported in this investigation. Generally, the temperature dependent rate constants for the destruction of nicotine were found to be [Formula: see text] s^-1 and [Formula: see text] s^-1 for ES1 and SM1 cigarettes respectively. In addition, the amount of nicotine evolved by ES1 cigarette was ~10 times more than the amount of nicotine released by SM1 cigarette.

CONCLUSION

The suggested mechanistic model for the formation of pyridine from the thermal degradation of nicotine in tobacco has been found to be agreement with the kinetic model proposed in this investigation. Consequently, the concentration of radical intermediates of tobacco smoke such as pyridinyl radical can be determined indirectly from a set of integrated rate laws. This study has also shown that different cigarettes can yield varying amounts of nicotine and pyridine depending on the type of cigarette primarily because of potential different growing conditions and additives introduced during tobacco processing. The activation energy of nicotine articulated in this work is consistent with that reported in literature.Graphical abstractThe anatomy of tobacco cigarette and the major chemistry involved during combustion (pyrolysis, GC-MS analysis, and kinetic modeling).

Kinetic modeling of nicotine in mainstream cigarette smoking

BACKGROUND

The attempt to understand the kinetic behavior of nicotine in tobacco will provide a basis for unraveling its energetics in tobacco burning and the formation of free radicals considered harmful to the cigarette smoking community. To the best of our knowledge, the high temperature destruction kinetic characteristics of nicotine have not been investigated before; hence this study is necessary especially at a time addiction science and tobacco research in general is gaining intense attention.

METHODS

The pyrolysis of tobacco under conditions simulating cigarette smoking in the temperature region 200-700 °C has been investigated for the evolution of nicotine and pyridine from two commercial cigarettes coded ES1 and SM1 using gas chromatography hyphenated to a mass selective detector (MSD). Moreover, a kinetic model on the thermal destruction of nicotine within a temperature window of 673 and 973 K is proposed using pseudo-first order reaction kinetics. A reaction time of 2.0 s was employed in line with the average puff time in cigarette smoking. Nonetheless, various reaction times were considered for the formation kinetics of nicotine.

RESULTS

GC-MS results showed the amount of nicotine evolved decreased with increase in the puff time. This observation was remarkably consistent with UV-Vis data reported in this investigation. Generally, the temperature dependent rate constants for the destruction of nicotine were found to be [Formula: see text] s^-1 and [Formula: see text] s^-1 for ES1 and SM1 cigarettes respectively. In addition, the amount of nicotine evolved by ES1 cigarette was ~10 times more than the amount of nicotine released by SM1 cigarette.

CONCLUSION

The suggested mechanistic model for the formation of pyridine from the thermal degradation of nicotine in tobacco has been found to be agreement with the kinetic model proposed in this investigation. Consequently, the concentration of radical intermediates of tobacco smoke such as pyridinyl radical can be determined indirectly from a set of integrated rate laws. This study has also shown that different cigarettes can yield varying amounts of nicotine and pyridine depending on the type of cigarette primarily because of potential different growing conditions and additives introduced during tobacco processing. The activation energy of nicotine articulated in this work is consistent with that reported in literature.Graphical abstractThe anatomy of tobacco cigarette and the major chemistry involved during combustion (pyrolysis, GC-MS analysis, and kinetic modeling).

Tobacco smoking is associated with decreased semen quality

BACKGROUND

Tobacco smoking is a public health issue and has been implicated in adverse reproductive outcomes including semen quality. Available data however provides conflicting findings. The objective of this study was to evaluate the effect of tobacco smoking on semen quality among men in Ghana.

METHODS

In this study, a total of 140 subjects were recruited, comprising 95 smokers and 45 non-smokers. Smokers were further categorized into mild, moderate and heavy smokers. Semen parameters such as sperm concentration, motility, viability and normal morphology were measured according to the World Health Organisation criteria.

RESULTS

The study showed that smokers had significantly lower semen volume, sperm concentration, sperm motility, total sperm count, sperm morphology, free testosterone and follicle stimulating hormone (p <0.05 respectively), compared with non-smokers. Smokers were at a higher risk of developing oligospermia, asthenozoospermia and teratozoospermia (OR = 3.1, 4.2 and, 4.7; p <0.05) than non-smokers.

CONCLUSION

Results demonstrated a decline in semen quality in a dose dependent tobacco smoking manner.

Sperm DNA damage-the effect of stress and everyday life factors

The clinical significance of sperm DNA damage lies in its association with natural conception rates and also might have a serious consequence on developmental outcome of the newborn. The aim of the present study is to determine whether stress and everyday life factors are associated with sperm DNA damage in adult men. The study population consisted of 286 men who attended the infertility clinic for diagnostic purposes and who had normal semen concentration of 20-300 m ml(-1) or with slight oligozoospermia (semen concentration of 15-20 m ml(-1)) (WHO, 1999). Participants were interviewed and provided a semen sample. The sperm chromatin structure assay was assessed using flow cytometry. In the present study, we found evidence for a relationship between sperm DNA damage parameters and everyday life factors. High and medium level of occupational stress and age increase DNA fragmentation index (P=0.03, P=0.004 and P=0.03, respectively). Other lifestyle factors that were positively associated with percentage of immature sperms (high DNA stainability index) included: obesity and cell phone use for more than 10 years (P=0.02 and P=0.04, respectively). Our findings indicate that stress and lifestyle factor may affect sperm DNA damage. Data from the present study showed a significant effect of age, obesity, mobile phone radiation and occupational stress on sperm DNA damage. As DNA fragmentation represents an extremely important parameter indicative of infertility and potential outcome of assisted reproduction treatment, and most of the lifestyle factors are easily modifiable, the information about factors that may affect DNA damage are important.

The hazardous effects of tobacco smoking on male fertility

The substantial harmful effects of tobacco smoking on fertility and reproduction have become apparent but are not generally appreciated. Tobacco smoke contains more than 4000 kinds of constituents, including nicotine, tar, carbonic monoxide, polycyclic aromatic hydrocarbons, and heavy metals. Because of the complexity of tobacco smoke components, the toxicological mechanism is notably complicated. Most studies have reported reduced semen quality, reproductive hormone system dysfunction and impaired spermatogenesis, sperm maturation, and spermatozoa function in smokers compared with nonsmokers. Underlying these effects, elevated oxidative stress, DNA damage, and cell apoptosis may play important roles collaboratively in the overall effect of tobacco smoking on male fertility. In this review, we strive to focus on both the phenotype of and the molecular mechanism underlying these harmful effects, although current studies regarding the mechanism remain insufficient.

Increased chromatin fragmentation and reduced acrosome integrity in spermatozoa of red deer from lead polluted sites

Vertebrates are constantly exposed to a diffuse pollution of heavy metals existing in the environment, but in some cases, the proximity to emission sources like mining activity increases the risk of developing adverse effects of these pollutants. Here we have studied lead (Pb) levels in spermatozoa and testis, and chromatin damage and levels of endogenous antioxidant activity in spermatozoa of red deer (Cervus elaphus) from a Pb mining area (n=37) and a control area (n=26). Deer from the Pb-polluted area showed higher Pb levels in testis parenchyma, epididymal cauda and spermatozoa, lower values of acrosome integrity, higher activity of glutathione peroxidase (GPx) and higher values of DNA fragmentation (X-DFI) and stainability (HDS) in sperm than in the control area. These results indicate that mining pollution can produce damage on chromatin and membrane spermatozoa in wildlife. The study of chromatin fragmentation has not been studied before in spermatozoa of wildlife species, and the sperm chromatin structure assay (SCSA) has been revealed as a successful tool for this purpose in species in which the amount of sperm that can be collected is very limited.

Recent insights on the significance of transcriptomic and metabolomic analysis of male factor infertility

Infertility is a worldwide reproductive health problem which affects approximately 15% of couples, with male factor infertility dominating nearly 50% of the affected population. The nature of the phenomenon is underscored by a complex array of transcriptomic, proteomic and metabolic differences which interact in unknown ways. Many causes of male factor infertility are still defined as idiopathic, and most diagnosis tends to be more descriptive rather than specific. As such, the emergence of novel transcriptomic and metabolomic studies may hold the key to more accurately diagnose and treat male factor infertility. This paper provides the most recent evidence underlying the role of transcriptomic and metabolomic analysis in the management of male infertility. A summary of the current knowledge and new discovery of noninvasive, highly sensitive and specific biomarkers which allow the expansion of this area is outlined.

Cryopreservation increases DNA fragmentation in spermatozoa of smokers

Smoking causes subfertility due to deterioration of spermatozoa including decreased concentration and abnormal morphology. Although evidence on the deleterious effects of smoking on spermatozoa parameters is well known, its interference with cryopreservation is not clear. This study aimed to investigate the effects of cryopreservation on sperm parameters and DNA fragmentation in non-smokers and smokers. Semen samples were obtained from 40 normospermic male volunteers of whom 20 were non-smokers and 20 smokers. Samples were analyzed in terms of motility, concentration, morphology, and DNA fragmentation before freezing and 1 and 3 months after freezing and thawing. Ultrastructural alterations were investigated by transmission electron microscopy. Sperm morphology seemed to be more affected after cryopreservation in samples obtained from smokers. Ultrastructural examination showed alterations in the integrity of the membranes and increased subacrosomal swelling. Before freezing, the increase in DNA fragmentation rate in smokers was not statistically significant compared to that of non-smokers. However, after thawing, the DNA fragmentation rates were significantly high in both non-smokers and smokers compared to their respective rates before freezing. The extent of the increase in DNA fragmentation rate was significantly higher in smokers after thawing compared to that of non-smokers. In conclusion, cryopreservation causes alterations in membrane integrity and increases DNA fragmentation, thus triggering relatively negative effects on the sperm samples of smokers compared to that of non-smokers.

[Evaluation of sperm functional parameters in normozoospermic infertile individuals]

OBJECTIVE

This study evaluated the integrity of the chromatin structure, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), DNA damage and lipid peroxidation of semen samples from infertile men classified as unexplained infertility.

METHODS

Between February 2010 and July 2011 semen parameters and functional tests were evaluated in 10 subjects with proven fertility, 10 that belong to general population and 8 with idiopathic infertility. In addition to the conventional semen analysis, the following unconventional seminal analysis were conducted: evaluation of ROS, MMP, sperm chromatin structure assay (SCSA) by flow cytometry, assessment of sperm membrane lipid peroxidation by spectrophotometry, and alkaline comet assay by electrophoresis.

RESULTS

We observed a significant increase (P<.05) in the production of ROS and the fragmentation or sperm DNA damage in the population of infertile men. There were no statistically significant differences (P>.05) in the analysis of sperm membrane integrity between the groups. Moreover, we observed significant correlations (P<.05) between SCSA and comet assay (r=0.86) and the production of intracellular ROS (r=-0.588).

CONCLUSION

The sperm from individuals with idiopathic infertility showed high levels of intracellular ROS and increased levels of DNA fragmentation in the sperm. These results suggest that these two parameters are related to unexplained infertility and therefore have clinical importance as a possible diagnostic and prognostic tool in the evaluation of idiopathic male infertility.

Paternal lifestyle as a potential source of germline mutations transmitted to offspring

Paternal exposure to high levels of radioactivity causes heritable germline minisatellite mutations. However, the effect of more general paternal exposures, such as cigarette smoking, on germline mutations remains unexplored. We analyzed two of the most commonly used minisatellite loci (CEB1 and B6.7) to identify germline mutations in blood samples of complete mother-father-child triads from the Norwegian Mother and Child Cohort Study (MoBa). The presence of mutations was subsequently related to general lifestyle factors, including paternal smoking before the partner became pregnant. Paternally derived mutations at the B6.7 locus (mutation frequency 0.07) were not affected by lifestyle. In contrast, high gross yearly income as a general measure of a healthy lifestyle coincided with low-mutation frequencies at the CEB1 locus (P=0.047). Income was inversely related to smoking behavior, and paternally derived CEB1 mutations were dose dependently increased when the father smoked in the 6 mo before pregnancy, 0.21 vs. 0.05 in smoking and nonsmoking fathers, respectively (P=0.061). These results suggest that paternal lifestyle can affect the chance of heritable mutations in unstable repetitive DNA sequences. To our knowledge, this is the first study reporting an effect of lifestyle on germline minisatellite mutation frequencies in a human population with moderate paternal exposures.

The Effects of Smoking and Alcohol Intake on Sperm Quality: Light and Transmission Electron Microscopy Findings

Objective:

To evaluate the effects of alcohol consumption and cigarette smoking on sperm quality using transmission electron microscopy and light microscopy.

Methods:

Semen samples were collected from 62 healthy men. The subjects were classified according to alcohol consumption and smoking status. Semen analysis was performed according to World Health Organization criteria. Transmission electron microscopy was used to examine sperm ultrastructure.

Results:

Heavy smoking (> 20 cigarettes/day) was associated with a decreased sperm count. Moderate/high alcohol consumption (≥15.4 g/day) was associated with an increase in morphologically abnormal sperm. Transmission electron microscopy revealed no effect of smoking on sperm ultrastructure. Alcohol consumption resulted in significant increases in morphologically abnormal nuclei and plasma membranes.

Conclusions:

Heavy smoking was associated with decreased sperm counts and alcohol consumption was associated with increased numbers of morphologically abnormal sperm.