Research trends and perspectives of male infertility: a bibliometric analysis of 20 years of scientific literature

Research trends in testosterone deficiency and management: A bibliometric analysis approach to quality improvement in urology resident education

INTRODUCTION

Previous work has demonstrated a deficiency in urology resident education when it comes to andrology and male infertility. We analyzed the top 100 most frequently cited and influential articles published on testosterone deficiency and its associated therapy, allowing trainees and clinicians to review and understand the characteristics of impactful literature for self-directed learning purposes.

METHODS

The ISI Web of Knowledge database was used to find articles on testosterone deficiency, hypogonadism, and replacement therapies. Relevant, peer-reviewed, English articles were included. Article details, including title, citation count, publication year, and more, were gathered. Articles were classified based on content (e.g. clinical outcomes, anatomy, and trends) using defined criteria.

RESULTS

The top 300 most cited were reviewed with 100 included. The most cited article had 774 citations, averaging 234 in the top 100. Publication years had peaks in 2003-2004 and 2006-2007. The US led in publications (56), followed by England (16), Germany (14), and Italy (13). Common affiliations included US Department of Veteran Affairs, Veterans Health Administration, RIC Research Education Clinical Center, and University of California System. Articles were categorized as LOE 2 (47), LOE 1 (22), and LOE 5 (21). Articles focused on clinical outcomes (71.7%), anatomy/biomechanics/physiology (14.1%), clinical guidelines (8.1%), and screening (4%). The "Journal of Clinical Endocrinology & Metabolism" published 26 of the top 100 cited articles.

CONCLUSIONS

This analysis highlights influential articles regarding testosterone deficiency and management. The discussed articles have significant clinical and therapeutic implications for the practicing urologist which may bolster deficits in current resident education.

Discovery of a novel miRNA involved in the regulation of male infertility in zebrafish

Azoospermia and asthenospermia are common manifestations of male infertility, but it needs further studies to understand the intrinsic regulation mechanism. As a popular model organism, zebrafish is often used to assess reproductive complications. In this study, by analyzing miRNA transcriptome of the mature triploid zebrafish testis afflicted with spermatogenic dysfunctions, leading to the identification of 36 miRNAs that are differentially expressed in comparison with diploid, which are predicted to target 2737 genes. Subsequent functional annotation of these genes pinpointed two miRNAs might association with spermatogenesis. Inhibitory experiments showed that NC_007115.7.7_998413 inhibited conducts a substantial decline in sperm density, and conducted lower embryo fertilization rate than control. And putative target genes qRT-PCR evaluation showed that spata2 was significant down-regulate upon inhibited NC_007115.7.7_998413. In summary, this research positions newly identified miRNA NC_007115.7.998413 as a regulatory factor in male zebrafish reproductive development, enhancing our comprehension of the molecular regulated pathways involved in spermatogenesis.

Leydig cell metabolic disorder act as a new mechanism affecting for focal spermatogenesis in Klinefelter syndrome patients: a real world cross-sectional study base on the age

Background

Klinefelter's syndrome (KS) was once considered infertile due to congenital chromosomal abnormalities, but the presence of focal spermatozoa changed this. The key to predict and promote spermatogenesis is to find targets that regulate focal spermatogenesis.

Objective

To explore the trend of fertility changes in KS patients at different ages and identify potential therapeutic targets.

Methods

Bibliometric analysis was used to collect clinical research data on KS from the Web of Science Core Collection (WoSCC) from 1992 to 2022. A cross-sectional study was conducted on 75 KS patients who underwent microscopic testicular sperm extraction (mTESE) from 2017 to 2022 in the real world. The reproductive hormones, testicular histopathology, androgen receptors, insulin-like factor 3 (INSL3) receptors and sperm recovery rate (SRR) were analyzed.

Results

Male infertility, dysplasia, Sertoli cells, Leydig cells, testosterone and spermatogenesis were the research focuses related to KS. Luteinizing hormone (LH), testosterone, and INSL3 were evaluation indicators of Leydig cell function that fluctuate with age. Testosterone and LH peaked at ages 13-19 and 30-45, while INSL3 only peaked at ages 13-19. 27 patients (27/75) recovered sperm through mTESE and experienced SRR peaks at the ages of 20, 28, 34, and 37. The SRR of fibrosis patients was 46.15%, fatty degeneration was 7.14%, and melanosis was 40.00%. The INSL3 and androgen receptors were highly expressed and roughly balanced in focal spermatogenesis.

Conclusion

Abnormal metabolism of Leydig cells led to imbalanced expression of INSL3 and androgen receptors, which might be a potential target for spermatogenesis in KS.

A Scientometric Evaluation of COVID-19 and Male Reproductive Research

The COVID-19 pandemic due to the SARS-CoV-2 coronavirus showed acute and prolonged effects on human health. In addition, over the past four years, there has been a tremendous surge in COVID-19-related scientific publications, as shown by bibliometric and scientometric studies. However, such analysis of the scientific literature is lacking in the area of male reproduction. The current scientometric study analyzes publication characteristics of articles related to male reproduction and COVID-19 infection. We used the Scopus database to analyze scientometric data (the number of publications, journals, countries, type of documents, and subject area) related to COVID-19 and male reproductive research. Our literature search identified 345 articles related to COVID-19 and male reproductive research. Most of the articles were published in the USA (n = 72), Italy (n = 55), and China (n = 51). Such research was mainly focused around medicine (57.1%), followed by biochemistry, genetics, and molecular biology (25.7%). Also, in the area of male reproduction, only 37.1% (n = 128) of the articles contributed towards original research, whereas 52.8% (n = 182) were review articles and editorials focusing more on sexual dysfunction than infertility. Such a small number of studies published on COVID-19-related effects on male reproduction warrants a significant increase in research, which is required to decipher the mechanism(s) underlying SARS-CoV-2 infection-associated impairment of male reproductive function.

Influence of Two Widely Used Solvents, Ethanol and Dimethyl Sulfoxide, on Human Sperm Parameters

To study mechanisms involved in fertility, many experimental assays are conducted by incubating spermatozoa in the presence of molecules dissolved in solvents such as ethanol (EtOH) or dimethyl sulfoxide (DMSO). Although a vehicle control group is usually included in such studies, it does not allow to evaluate the intrinsic effect of the solvent on sperm parameters and its potential influence on the outcome of the experiment. In the present study, we incubated human spermatozoa for 4 h in a capacitation medium in the absence or the presence of different concentrations of EtOH and DMSO (0.1, 0.5, 1.0, and 2.0%) to assess the impact of these solvents on sperm motility, vitality, capacitation, and acrosome integrity. The presence of statistically significant relationships between increasing solvent concentrations and the investigated parameters was assessed using linear mixed models. A significant effect was observed with both solvents for total and progressive sperm motilities. We also evaluated the effect of time for these parameters and showed that the influence of the solvents was stable between 0 and 4 h, indicating an almost direct impact of the solvents. While EtOH did not influence sperm vitality and acrosome integrity, a significant effect of increasing DMSO concentrations was observed for these parameters. Finally, regarding capacitation, measured via phosphotyrosine content, although a dose-dependent effect was observed with both solvents, the statistical analysis did not allow to precisely evaluate the intensity of the effect. Based on the results obtained in the present study, and the corresponding linear mixed models, we calculated the concentration of both solvents which would result in a 5% decline in sperm parameters. For EtOH, these concentrations are 0.9, 0.7, and 0.3% for total motility, progressive motility, and capacitation, respectively, while for DMSO they are 1.5, 1.1, >2, 0.3 and >2% for total motility, progressive motility, vitality, capacitation, and acrosome integrity, respectively. We recommend using solvent concentrations below these values to dissolve molecules used to study sperm function in vitro, to limit side effects.

Worldwide research trend of publications concerning spermatogenesis over past 10 years: A bibliometric study

Fertility is a hot topic and many publications on spermatogenesis has been published during the past 10 years (2012-2021). This study aims to analyse the research trends and dynamics on spermatogenesis using bibliometric methods. In this study, only articles with an annual average citation of 1 or more were selected for analysis, and a total of 4849 articles were analysed. The results show that in the field of spermatogenesis over the past 10 years, mainland China and the United States are the two leading countries, and international collaboration becoming increasingly close; Nanjing Medical University is the most widely published and collaborated institution; PLOS One and Biology of Reproduction are the most published and cited journals; Andrologia is the most popular journal in Andrology subspecialty; Zhang has made the largest contribution, with the highest number of publications and total citations; 'testis', 'male infertility' and 'apoptosis' were the most researched trend topics. The future trends on spermatogenesis are likely to favour hot topics such as 'inflammation', 'transcriptomics' and 'exosomes'. In the conclusion, our study analyses the research trends on spermatogenesis over the past 10 years, which will provide a reference for researchers in this field.

Testicular ultrasound examination and hemodynamics of patients with azoospermia

The most difficult form of male infertility to treat is azoospermia. Azoospermia is defined as the complete absence of spermatozoa in the ejaculate. The age of the patients who underwent clinical and diagnostic studies varied between 22 and 45 years. Among 119 examined patients with azoospermia, 58.0% were diagnosed with secretory infertility. In 42.0% patients, the presence of spermatogenesis in excretory-obturational infertility was established. Among 69 patients with secretory infertility, 23 had azoospermia in the absence of spermatozoa and spermatogenic cells, which accounted for 33.3% of all patients with secretory infertility (in particular, 2 with leukocytospermia, which indicated damage to the tubular apparatus as a result of previous orchitis). In 66.6% patients, azoospermia was observed in the absence of spermatozoa, but in the presence of precursor cells of spermatogenesis. 11.5% patients out of 69 (group 1) were diagnosed with concomitant diseases. We see that arterial hypertension, diseases of the gastrointestinal tract, liver, and kidneys occur. Hereditary diseases were not detected in the examined patients. Pain of varying intensity was found in 6.7% of patients, varying degrees of testicular hypoplasia were found in 7.6%, dysuria in 13.4%, epididymitis in history 8.4%; history of epidemic mumps 6.7%; 12.6% had depression, restlessness, sleep disorders, and 21.0% had erectile dysfunction. According to clinical examination and ultrasound, chronic prostatitis is suspected in 19.2% of patients. An increase in the number of leukocytes in the blood was found in 13.2% patients. According to ultrasound, 60.5% of the patients with azoospermia had normal testicular sizes, and 39.5% had reduced testes. The volume of the testicles in the control group was 22.3 ± 2.1 cm³ on average, varying from 18.3 to 25.1 cm³. In the group with azoospermia, the volume of the testicles was on average 16.7 ± 1.7 cm³ and varied from 8.2 to 21.1 cm³, that is, the volume of the testicles in patients with azoospermia was on average 1.3 times smaller compared to normozoospermia. In the obstructive form of azoospermia, diffuse changes were detected in both testicles, probably obturational changes. Hypoplasia of the left testicle and increased echogenicity were observed in the non-obstructive form of azoospermia. The veins of the spermatic cord were moderately dilated. There was a normal amount of free fluid in the scrotum. According to elastography, the elasticity of the testicles was above normal. Obturational processes in the testicles were suspected. The hemodynamic parameters of testicular parenchymal blood flow in infertile men obtained by ultrasound dopplerography are of important diagnostic value. The average value of the linear blood flow velocity in the arteries of the parenchyma in men with normozoospermia was 0.107 ± 0.015 m/s on the right, and 0.103 ± 0.012 m/s on the left. With azoospermia, the average value of the linear velocity of blood flow on the right was 0.086 ± 0.012 m/s, and on the left – 0.084 ± 0.008 m/s. Thus, the hemodynamic indicators of the scrotum show that the most pronounced changes are found in men with azoospermia in the absence of spermatogenesis.

Male personal heat exposures and fecundability: A preconception cohort study

BACKGROUND

Several studies indicate adverse effects of selected heat exposures on semen quality, but few studies have directly evaluated fertility as an endpoint.

OBJECTIVE

We evaluated prospectively the association between male heat exposures and fecundability, the per-cycle probability of conception.

MATERIALS AND METHODS

We analyzed data from 3041 couples residing in the United States or Canada who enrolled in a prospective preconception cohort study (2013-2021). At enrollment, males reported on several heat-related exposures, such as use of saunas, hot baths, seat heaters, and tight-fitting underwear. Pregnancy status was updated on female follow-up questionnaires every 8 weeks until conception or a censoring event (initiation of fertility treatment, cessation of pregnancy attempts, withdrawal, loss to follow-up, or 12 cycles), whichever came first. We used proportional probabilities regression models to estimate fecundability ratios (FR) and 95% confidence intervals (CIs) for the association between heat exposures and fecundability, mutually adjusting for heat exposures and other potential confounders.

RESULTS

We observed small inverse associations for hot bath/tub use (≥3 vs. 0 times/month: FR = 0.87, 95% CI: 0.70-1.07) and fever in the 3 months before baseline (FR = 0.94, 95% CI: 0.79-1.12; one cycle of follow-up: FR = 0.84, 95% CI: 0.64-1.11). Little association was found for sauna use, hours of laptop use on one's lap, seat heater use, time spent sitting, and use of tight-fitting underwear. Based on a cumulative heat metric, FRs for 1, 2, 3, and ≥4 versus 0 heat exposures were 0.99 (95% CI: 0.87-1.12), 1.03 (95% CI: 0.89-1.19), 0.94 (95% CI: 0.74-1.19), and 0.77 (95% CI: 0.50-1.17), respectively. Associations were stronger among men aged ≥30 years (≥4 vs. 0 heat exposures: FR = 0.60, 95% CI: 0.34-1.04).

CONCLUSION

Male use of hot tubs/baths and fever showed weak inverse associations with fecundability. Cumulative exposure to multiple heat sources was associated with a moderate reduction in fecundability, particularly among males aged ≥30 years.

The top 100 cited articles in pediatric urology: A bibliometric analysis

INTRODUCTION

In the last 120 years, the field of pediatric urology has seen an exponential growth. In this time, there has not been a comprehensive review of top cited articles within the field.

OBJECTIVES

We aim to identify and categorize the top 100 most cited peer-reviewed articles in pediatric urology using citation analysis.

STUDY DESIGN

We searched for articles in the Web of Science™ Core Collection between 1900 and 2020 using terms specific to pediatric urology. We identified relevant pediatric urology articles and selected the top 100 most cited articles. We analysed trends over time for topics and categories and we evaluated the relatedness of these articles using citation analysis software.

RESULTS

The top 100 most cited articles in pediatric urology were published between 1958 and 2016 in 26 countries, across 181 institutions, and in 46 journals. The median number of citations per article was 268 (IQR 225.75-394.25). Clinical manuscripts were the most common among the top 100 cited articles (n = 64) and the most common topic was genital conditions (e.g., penile, inguinal, or testis but not including hypospadias) (n = 19; 16.5%; total citations = 6591). When using bibliometric software to analyse relatedness among the top 100 articles based on citation of one another, we identified 11 clusters of 3 or more articles which corresponded to topics like those we defined a priori (Summary Figure). We found that a greater proportion of articles describing surgical techniques were published prior to 1987 (n = 6, 38%) as compared to after 1987 (n = 11, 13%), while the proportion of basic science articles has increased.

DISCUSSION

This is the first study to analyse the most cited articles in pediatric urology. There was a lower median citation per article and fewer prospective studies in this list compared to other urologic sub-specialties. Similar to other clinical specialties, the focus has moved from describing and comparing operative techniques to exploring mechanisms of disease. This study is limited by using a single parameter (citation rate) and a single citation database.

CONCLUSION

The list of top 100 most cited articles in pediatric urology is an important resource for clinicians and trainees to understand the body of knowledge and trajectory of this field. It charts the evolution of the field and highlights areas of potential investigation. This objective approach to literature review can facilitate future research and education efforts.

Epididymosomes: A potential male fertility influencer

During transit and storage in epididymis, spermatozoa undergo final maturation, acquire motility, functional competence and the ability to fertilise an oocyte. Epididymal secretions contain a complex biochemical milieu of diverse inorganic ions, proteins, metabolites and other molecules. Since it is believed that spermatozoa are translationally silent, proteins appearing in them are thought to be synthesised elsewhere, including epididymis, and then incorporated to the cells. One of the important mechanisms suggested to be involved in transfer of epididymal secretions to spermatozoa is through exosomes called epididymosomes. Epididymosomes released from the epididymal epithelium contain proteins, noncoding RNAs and distinct set of lipids that are transferred to spermatozoa while they pass through the different epididymal regions. Owing to the importance of these molecules for sperm maturation and fertilising ability, research on epididymosomes has gained increasing attention during the last decade. This review is focused on epididymosomes, with emphasis on recent advances in the understanding of mechanisms of epididymosomal cargo transfer to spermatozoa and potential roles of epididymosomes in sperm function and beyond. Possibilities of utilising the molecular signatures of epididymosomes as a tool for male fertility assessment are also discussed.

Cystatin C and Seminal Parameter Evaluation in Patients with End-Stage Renal Disease

OBJECTIVE

We aimed to investigate the possible relationship between seminal parameters and cystatin C seminal levels in an infertility evaluation of chronic hemodialysis patients.

MATERIALS AND METHODS

This was a cross-sectional study, aged 18-60 years, in a group of 60 men undergoing hemodialysis (case) for more than 6 months, and a group of 15 healthy men (control) without clinical or laboratory signs of genitourinary tract infection. We performed a spermogram, hormonal profile, and assessment of leukocytes and cystatin levels in the semen.

RESULTS

The ages in the case and control were similar (p = 0.060). The seminal cystatin was significantly different between the case group and control group (41.16 ± 26.59 vs. 79.00 ± 05.68 mg/l, respectively, p < 0.001) and between normospermia and oligospermia (83.50 ± 02.40 vs. 30.34 ± 02.52 mg/l, respectively, p < 0.001). The mean seminal cystatin levels identified by the degrees of oligospermia (severe, moderate, and slim) were similar to each other (p > 0.05) and significantly different (p < 0.05) in relation to normospermia in the case group. The seminal cystatin levels positively correlated (p < 0.05) with sperm motility and sperm density.

CONCLUSION

Seminal cystatin levels are associated with the numerical and motility changes evidenced in the spermogram and may be of help in the initial evaluation of clinical suspicion of sub-fertility and infertility.

Effects of Mediterranean diet on semen parameters in healthy young adults: a randomized controlled trial

BACKGROUND

Dietary regimens have so far been studied as possible determinants of semen quality and fertility. The aim of this study was to evaluate the effects of a Mediterranean diet, as compared with a low-fat diet, on seminal parameters of young healthy adults from southern Italy.

METHODS

In a randomized controlled trial, 160 young adults aged 18-30 years were assigned to Mediterranean diet (N.=80) or a low-fat diet (N.=80). The primary outcome measures were changes in semen parameters after six months.

RESULTS

Mean age of participants in the study was 24.7 years. There was no difference in baseline semen parameters of men randomized to Mediterranean diet or low-fat diet. After the entire follow-up, participants in both groups showed a significant increase in sperm concentration and sperm total count, with significant differences favoring the Mediterranean diet group (sperm concentration, 1.93 M/mL 95% CI [1.22 to 3.64], P=0.027; total sperm count 8.02 M 95% CI [1.51 to 15.45], P=0.035). No differences in other semen parameters were found between groups.

CONCLUSIONS

In healthy young adults, the consumption of Mediterranean diet was associated with an improvement of both sperm concentration and total count, as compared with a low-fat diet.

Recent advances and controversies in diagnosing and treating male infertility

Interest in male infertility has increased, as it plays an important role in up to 50% of couples struggling with infertility, which is an estimated 48.5 million couples globally. Despite recent advances, diagnosing and treating male infertility remain a significant clinical challenge owing to complex multifactorial pathways and the diversity of treatment options. This review will assess current controversial topics on male infertility such as the use of home-based semen testing, management of subclinical varicocele, and recent advances in the field of sperm proteomics.

A scientometric analysis of research publications on male infertility and assisted reproductive technology

Assisted reproductive technologies (ART) are considered as one of the primary management options to address severe male factor infertility. The purpose of this study was to identify the research trends in the field of male infertility and ART over the past 20 years (2000-2019) by analysing scientometric data (the number of publications per year, authors, author affiliations, journals, countries, type of documents, subject area and number of citations) retrieved using the Scopus database. We used VOS viewer software to generate a network map on international collaborations as well as a heat map of the top scientists in this field. Our results revealed a total of 2,148 publications during this period with Cleveland Clinic Foundation contributing the most (n = 69). The current scientometric analysis showed that the research trend on ART has been stable over the past two decades. Further in-depth analysis revealed that density gradient centrifugation (46%) and intracytoplasmic sperm injection (59.2%) are the most reported techniques for sperm separation and ART, respectively. Additionally, azoospermia was the most studied clinical scenario (60.6%), with majority of articles reporting pregnancy rate (47.25%) as the primary reproductive outcome for ART. This study provides insight into the current focus of research in the area of male infertility and ART as well as the areas that require further research in future.

Scientific landscape of oxidative stress in male reproductive research: A scientometric study

Unraveling the role of reactive oxygen species and associated oxidative stress (OS) in male reproduction is one of the key areas of male reproductive research. This article illustrates the scientific landscape of OS in male reproductive research over the past several decades (1941-2018) using a scientometric approach. Scientometric data (articles per year, authors, affiliations, journals, and countries) on OS related to male reproduction were retrieved from the Scopus database and analyzed for each decade. Our analysis revealed an increasing trend in OS-based male reproductive research from 1941 to 2018 with a steep raise in publications and research collaborations starting from the period 1991-2000 (R² = 0.81). Semen abnormalities and varicocele were the major areas investigated in relation to OS with the highest positive trend in publications from the time interval 1981-1990 to 2011-2018. Analysis of publications based on OS assessment techniques revealed chemiluminescence (n = 180) and evaluation of antioxidants (n = 300) as the most widely used direct and indirect tests, respectively. Furthermore, prognostic/diagnostic studies on OS evaluation increased significantly over the time. Our analysis highlights the evolution of OS in male reproductive research and its emergence as an important prognostic and diagnostic tool in the evaluation of male infertility.

Assessing Clinical Embryology Research: A Global Bibliometric Analysis

Background and Objectives: The evaluative strength of available bibliometric tools in the field of clinical embryology has never been examined in the literature. The aim is to bring insight regarding the identity of clinical embryology research, introducing concerns when solely relying on the methodology of bibliometric analysis. Materials and Methods: An all-inclusive analysis of the most bibliometrically highlighted scientific contributions regarding the cornerstones of clinical embryology was performed employing the Scopus, Web of Science (WoS) and PubMed databases, between 1978–2018. An analysis of the number of publications, respective citations and h-index, g-index, along with m-quotient is presented. The top 30 contributing authors for each distinctive area of research are listed. An attempt at visualizing the yearly published articles, clusters, and collaborations of authors, along with the geographic origin of publications, is also presented. Results: Combining all searches and keywords yielded 54,522 results. In the Scopus database, employing the keyword “In Vitro Fertilization” yielded 41,292 results. The publications of the top five authors in each research field were analytically presented and compared to the total number of publications for each respective field. The research field of Preimplantation Genetic Diagnosis/Screening/Testing was allocated the highest percentage of publications produced by the top five authors. Regarding journal bibliometrics, based on the year 2017 metrics, there are only 29 journals according to WoS that refer to “Reproductive Biology”, ranking it 187th among 235 disciplines. The USA produced the highest number of publications (12,537). Conclusion: Results indicate an explosion of interest published in the literature regarding the field of clinical embryology. Further analysis on collaborations and the trends involved should be of added value as productivity between countries varies significantly. This may guide researchers, in vitro fertilization professionals, and prospective authors during literature search, while proving useful regarding manuscript design and concurring on keywords and abstract content.

A bibliometric analysis of international publication trends in premature ejaculation research (2008-2018)

The incidence of premature ejaculation (PE) has been on the rise over the years. Thus, significant research efforts have been directed toward understanding the pathogenesis and hence treatment of PE. Here, we performed a comprehensive analysis of the worldwide trends in research outputs in the field of PE. This study investigated the universal findings of previous PE studies and the trending issues surrounding the condition. We employed the Web of Science Core Collection for data collection. The Excel (2016) and CiteSpace IV were used for information analysis. The information was categorized using journal names, institutions, research frontiers, citation reports, regions/countries, and authors. A sum of 886 publications concerning PE between 2008 and 2018 were identified as of July 6, 2019. The highest number of publications was identified in the Journal of Sexual Medicine published. The United States of America (USA) had the highest number of publications and H-index value. The highest co-citations were from Waldinger MD. The most common keyword was 'drug treatment'. A steady pattern was observed for PE publications done between the period of 2008-2018. Thus, the USA is at the forefront of research on PE research. The interesting advanced research frontiers were drug treatment, circumcision, and sertraline.

Tracking research trends and hotspots in sperm DNA fragmentation testing for the evaluation of male infertility: a scientometric analysis

BACKGROUND

This article describes the research trends in sperm DNA fragmentation (SDF) over the past 20 years (1999-2018) using a scientometric approach.

METHODS

A stepwise approach was adopted to retrieve scientometric data (articles per year, authors, affiliations, journals, countries) from Scopus and analyze the publication pattern of SDF with reference to key areas of research in the field of Andrology.

RESULTS

A total of 2121 articles were retrieved related to SDF. Our data revealed an increasing research trend in SDF (n = 33 to n = 173) over the past 20 years (R² = 0.894). Most productive country in publications was the USA (n = 450), while Agarwal A. (n = 129) being the most productive author. Most of the articles in SDF were primarily focused on lifestyle (n = 157), asthenozoospermia (n = 135) and varicocele (130). Mechanistic studies on SDF were published twice as much as prognostic/diagnostic studies, with significant emphasis on oxidative stress. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was the most widely used technique to evaluate SDF. Publications on SDF related to assisted reproductive techniques also showed a linear increasing trend (R² = 0.933).

CONCLUSIONS

Our analysis revealed an increasing trend in SDF publications predominantly investigating lifestyle, asthenozoospermia and varicocele conditions with TUNEL being the most widely used technique. A substantial increase in research is warranted to establish SDF as prognostic/diagnostic parameter to evaluate clinical scenarios and ART outcomes.

Sexual health services in the Arab region: Availability, access, and utilisation

Sexual health is shaped by cultural, economic, and social norms in society. In the Arab region, cultural sensitivities and taboos surrounding sexuality are prominent and may prevent individuals from accessing and utilising sexual health services. It is important to map out available sexual health services to identify the challenges in availability, access, and treatment, and determine opportunities for improvement. We collected data on sexual health services through (1) relevant published and unpublished literature, (2) Arab media which included forums, websites, blogs and posts, and online surveys conducted in the Arab region, (3) a questionnaire emailed to sexual and reproductive health experts, organisations, clinics, and non-governmental organisations (NGOs), (4) phone and in-person formal and informal interviews with sexual health experts in the field, and (5) advice and recommendations from sexual health experts attending a World Health Organization (WHO) consultation meeting in Dubai related to sexual health in the Arab region. Although there is significant progress when it comes to the availability and provision of sexual health services in Arab countries, there is still a lot to be done to ensure that appropriate needs are met. This study discusses the implication of findings to inform programme and policy implementation in the region.

Is there plagiarism in the most influential publications in the field of andrology?

Plagiarism is a common form of academic misconduct that extensively jeopardises the quality of scientific publication. The purpose of this study is to determine the extent of plagiarism in the most influential andrology articles. A total of 77 highly cited andrology articles were analysed for their similarity index using iThenticate and Turnitin. The articles were categorised based on the year (before and on/after 2000) and type of publication (review and research articles), and the similarity indices were compared. Furthermore, the analysed articles were categorised based on the level of similarity using an arbitrary similarity index range (low: ≤10, moderate: 11-20, high: 21-50 and very high: >50) and average incidence rate (%) was determined. Our analysis revealed a higher percentage of the similarity indices for reviews than research articles. We noticed a higher similarity index for articles published on/after 2000 than those published before. The majority of the influential articles in the field of andrology showed a low similarity index, while some articles exhibited moderate to high levels of similarity. These findings support the need for the development of similarity index guidelines as a major pre-requisite for establishing a more transparent and efficient system to address plagiarism in scientific publications.

An In-Depth Bibliometric Analysis and Current Perspective on Male infertility Research

Purpose

Male infertility is emerging as a major, escalating global health problem that imposes the need to investigate research trends in male infertility. The purpose of this study is to analyze male infertility research trends in the past 20 years using the bibliometric database from Scopus.

Materials and Methods

In order to perform an in-depth bibliometric analysis, we propose a ‘Funnel Model’, which includes several layers representing different sub-areas of male infertility research. Adopting this Funnel Model, using Scopus, we retrieved relevant bibliometric data (articles per year, authors, affiliations, journals, and countries) for various areas of male infertility research and performed descriptive statistics.

Results

The bibliometric analysis showed an exponential increase in male infertility research in the last 20 years. USA dominated in research output, with Agarwal, A. as the most prolific researcher. Testicular cancer, obesity and metabolic syndrome, and azoospermia were found to dominate male infertility research, whereas erectile dysfunction and unexplained male infertility had lesser attention. Interestingly, prognostic/diagnostic and mechanistic studies have significantly increased in parallel over the last 20 years. Furthermore, our bibliometric analysis revealed fewer publications in proteomics, transcriptomics and metabolomics when compared to genomics. Also, an increasing trend in publication was seen in assisted reproductive technology (ART) research.

Conclusions

An integrated and steep escalation in the field of omics and ART research appears to be a prerequisite for further development of future diagnostic and therapeutic strategies for male infertility.

The 100 most influential manuscripts in andrology: a bibliometric analysis

Background

As the specialty of Andrology expands it is important to establish the most important studies that have shaped, and continue to shape, current research and clinical practice. Bibliometric analysis involving a citation rank list is an established means by which to identify the published material within a given field that has greatest intellectual influence. This bibliometric analysis sought to identify the 100 most influential manuscripts in Andrology, as well as the key research themes that have shaped contemporary understanding and management of andrological conditions.

Methods

The Thompson Reuters Web of Science citation indexing database was interrogated using a number of search terms chosen to reflect the full spectrum of andrological practice. Results were ranked according to citation number and further analysed according to subject, first and senior author, journal, year of publication, institution and country of origin.

Results

The Web of Science search returned a total of 24,128 manuscripts. Citation number of the top 100 articles ranged from 2819 to 218 (median 320). The most cited manuscript (by Feldman et al., The Journal of Urology 1994; 2819 citations) reported the prevalence and risk factors for erectile dysfunction (ED) in the Massachusetts Male Ageing Study. The Journal of Urology published the highest number of manuscripts (n = 11), followed by the New England Journal of Medicine (n = 10). The most common theme represented within the top 100 manuscripts was erectile dysfunction (n = 46), followed jointly by hypogonadism and male factor infertility (n = 24 respectively).

Conclusion

Erectile dysfunction should be considered the most widely researched, published and cited field within andrological practice. This study provides a list of the most influential manuscripts in andrology and serves as a reference of what comprises a ‘highly citable’ paper for both researchers and clinicians.

Fatemeh Makkizadeh Ph.D., Esmaeil Bigdeloo M.A

Background

The Co-word analysis has the ability to identify the intellectual structure of knowledge in a research domain and reveal its subsurface research aspects.

Objective

This study examines the intellectual structure of knowledge in the field of Andrology during the period 2008-2017 using Co-word analysis.

Materials and Methods

In this descriptive-analytical study with a scientometric approach, the WoS database was searched for papers indexed under “Andrology” over the period 2008–2017. The data were analyzed using Co-word, clustering methods, and strategic diagram with the help of SPSS, UcInet, RavarPreMap and VOSviewer software.

Results

The highest publication rate in the area of Andrology was seen in countries like the USA, China, Italy, and Iran. The top three journals that published papers on the field were Fertility and Sterility, Andrologia, Human reproduction. The results showed that the keyword “Spermatozoa” and two pairs of frequently used keywords, namely “Azoospermia * Oligospermia” were the most frequent in the field of Andrology. The results of hierarchical clustering led to 13 clusters. The clusters “Reproductive Techniques” and “Spermatogenesis” are the core clusters and play an effective role. The "Post-Testicular causes” and “Neoplasm” clusters are in marginal.

Conclusion

This study represented that Co-word analysis can well illustrate the intellectual structure of an area. Considering the frequency of keywords along with the clusters obtained, it seems that the majority of research approach was seen on infertility treatments, especially through assisted reproductive technology. Despite the importance of psychological aspects as well as education of reproductive health, these subjects have not been sufficiently considered.

Testicular organoids: a new model to study the testicular microenvironment in vitro?

BACKGROUND

In recent decades, a broad range of strategies have been applied to model the testicular microenvironment in vitro. These models have been utilized to study testicular physiology and development. However, a system that allows investigations into testicular organogenesis and its impact in the spermatogonial stem-cell (SSC) niche in vitro has not been developed yet. Recently, the creation of tissue-specific organ-like structures called organoids has resurged, helping researchers to answer scientific questions that previous in vitro models could not help to elucidate. So far, a small number of publications have concerned the generation of testicular organoids and their application in the field of reproductive medicine and biology.

OBJECTIVE AND RATIONALE

Here, we aim to elucidate whether testicular organoids might be useful in answering current scientific questions about the regulation and function of the SSC niche as well as germ cell proliferation and differentiation, and whether or not the existing in vitro models are already sufficient to address them. Moreover, we would like to discuss how an organoid system can be a better solution to address these prominent scientific problems in our field, by the creation of a rationale parallel to those in other areas where organoid systems have been successfully utilized.

SEARCH METHODS

We comprehensively reviewed publications regarding testicular organoids and the methods that most closely led to the formation of these organ-like structures in vitro by searching for the following terms in both PubMed and the Web of Science database: testicular organoid, seminiferous tubule 3D culture, Sertoli cell 3D culture, testicular cord formation in vitro, testicular morphogenesis in vitro, germ cell 3D culture, in vitro spermatogenesis, testicular de novo morphogenesis, seminiferous tubule de novo morphogenesis, seminiferous tubule-like structures, testicular in vitro model and male germ cell niche in vitro, with no restrictions to any publishing year. The inclusion criteria were based on the relation with the main topic (i.e. testicular organoids, testicular- and seminiferous-like structures as in vitro models), methodology applied (i.e. in vitro culture, culture dimensions (2D, 3D), testicular cell suspension or fragments) and outcome of interest (i.e. organization in vitro). Publications about grafting of testicular tissue, germ-cell transplantation and female germ-cell culture were excluded.

OUTCOMES

The application of organoid systems is making its first steps in the field of reproductive medicine and biology. A restricted number of publications have reported and characterized testicular organoids and even fewer have denominated such structures by this method. However, we detected that a clear improvement in testicular cell reorganization is recognized when 3D culture conditions are utilized instead of 2D conditions. Depending on the scientific question, testicular organoids might offer a more appropriate in vitro model to investigate testicular development and physiology because of the easy manipulation of cell suspensions (inclusion or exclusion of a specific cell population), the fast reorganization of these structures and the controlled in vitro conditions, to the same extent as with other organoid strategies reported in other fields.

WIDER IMPLICATIONS

By way of appropriate research questions, we might use testicular organoids to deepen our basic understanding of testicular development and the SSC niche, leading to new methodologies for male infertility treatment.

LncRNA gadd7, increased in varicocele patients, suppresses cell proliferation and promotes cell apoptosis

Varicocele-related sperm damages are usually caused by oxidative stresses. Growing evidence indicates that lncRNA growth arrested DNA-damage inducible gene 7 (gadd7) is involved in the regulation of the oxidative stress responses. In this study, we measured the expression level of gadd7 in the sperm and found that the expression of gadd7 was significantly up-regulated in patients with varicocele compared with the healthy control. The relative expression level of gadd7 was negatively correlated with the sperm count. Overexpression of gadd7 suppressed cell proliferation and promoted cell apoptosis in mouse spermatocyte-derived cell lines GC-1 and GC-2. Furthermore, the protein level of Bax was raised while Bcl2 expression was reduced after overexpression of gadd7. This work provides a potential novel insight for the varicocele-related sperm impairment and male infertility.

Dietary patterns and semen quality: a systematic review and meta-analysis of observational studies

A number of studies have examined the association between dietary patterns and semen quality, but the findings have been inconclusive. Herein, we conducted a systematic review and meta-analysis of observational studies to assess the association between dietary patterns and semen quality. PubMed, Cochrane library, Science direct, Scopus, Google Scholar, and ISI web of science databases were searched up to August 2016 for observational studies assessing the association between common dietary patterns and sperm quality markers. Data were pooled by the generic inverse variance method with random effects and expressed as mean differences with 95% confidence intervals (CIs). Heterogeneity was assessed (Cochrane Q-statistic) and quantified (I² -statistic). The Newcastle-Ottawa Scale assessed study quality. Six eligible studies, involving 8207 participants, were included in our systematic review and meta-analysis. The pooled mean difference of sperm concentration for the healthy dietary pattern versus unhealthy dietary pattern intake was mean difference: 0.66; 95% CI, 0.305-1.016; p < 0.001. In comparison with those who had the highest adherence to healthy dietary pattern, individuals in the lowest adherence had significantly lower level of sperm concentration. However, no significant association was seen between eating patterns and other semen quality. Healthy dietary pattern seems to be associated with elevated sperm concentration level. Further longitudinal studies are needed to clarify this relationship.