Browsing by Author "Plessis, Stefan S. du"

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Cementing the relationship between conventional and advanced semen parameters
(2021) Plessis, Stefan S. du
Background: Afordable conventional semen analysis remains a fundamental procedure to be performed routinely during the diagnosis of male infertility. Advanced semen analyses provide valuable clinical insights in treatmentrelated decision-making, but these are highly expensive and lack universal standardization. This study aimed at determining the relationship between conventional semen parameters, measured with assistance of computer-aided sperm analysis (CASA), and a set of advanced semen tests. Basic semen analysis (n = 124) was performed according to the World Health Organization (WHO) guidelines. Sperm DNA fragmentation and intracellular superoxide (O2 −• ) levels were assessed by fow cytometry. Seminal plasma thiobarbituric acid reactive substances (TBARS) levels as well as superoxide dismutase (SOD) and catalase (CAT) activity were measured by spectrophotometry. Spearman’s rank correlation coefcient was used, with signifcance set at p < 0.05. Results: Semen pH correlated negatively with TBARS (p < 0.01). The proportions of total and progressively motile as well as rapid spermatozoa correlated positively with CAT activity (p < 0.05). Sperm viability correlated negatively with both O2 −• (p < 0.05) and DNA fragmentation (p = 0.01), while normal morphology correlated negatively with O2 −• levels (p < 0.05) and positively with CAT activity (p < 0.05). Straight-line velocity (VCL) and average-path velocity (VAP) correlated negatively with both O2 −• (p < 0.01) and TBARS (p < 0.01). Amplitude of lateral head displacement (ALH) correlated negatively with O2 −• (p < 0.01) and DNA fragmentation (p < 0.01), while its correlation with SOD activity was positive (p < 0.05). Conclusion: The results obtained from this study support the validity of some CASA parameters as sensitive indicators of changes in sperm oxidative status and DNA integrity. Predicting advanced from conventional parameters through the building of linear regression models should be considered for future studies.
Male infertility: A proximate look at the advanced glycation end products
(2020) Plessis, Stefan S. du
Abstract: Advanced glycation end products (AGEs) are products of cascades of non-enzymatic glycosylation. They are formed over a period of hours to days, depending on the protein lifetime. AGEs acts by independently producing reactive oxygen species (ROS) or by binding to their receptors. Binding of AGE to the receptor for advanced glycation end products (RAGE) has been shown to play a role in physiological processes, including lung homeostasis, bone metabolism, neuronal systems and the immune system. When in excess, they take part in the pathogenesis of diseases such as diabetes mellitus, cardiovascular diseases, neurodegenerative diseases, and etcetera. The cause of male infertility is considered unexplained in many cases, suggesting that there are gaps in the mechanistic knowledge of sperm production and function, especially, pathways involved in the physiochemical protein regulation of spermatogenesis. It is therefore important to consider areas of research highlighting protein modification and identification and their implication for male fertility.
Oxidative Stress and Male Infertility: Evidence From a Research Perspective
(2022) Omolaoye, Temidayo S.; Plessis, Stefan S. du
Abstract: Male fertility potential can be influenced by a variety of conditions that frequently coincide. Spermatozoa are particularly susceptible to oxidative damage due to their limited antioxidant capacity and cell membrane rich in polyunsaturated fatty acids (PUFAs). The role of oxidative stress (OS) in the etiology of male infertility has been the primary focus of our Stellenbosch University Reproductive Research Group (SURRG) over the last 10 years. This review aims to provide a novel insight into the impact of OS on spermatozoa and male reproductive function by reviewing the OS-related findings from a wide variety of studies conducted in our laboratory, along with those emerging from other investigators. We will provide a concise overview of the production of reactive oxygen species (ROS) and the development of OS in the male reproductive tract along with the physiological and pathological effects thereof on male reproductive functions. Recent advances in methods and techniques used for the assessment of OS will also be highlighted. We will furthermore consider the current evidence regarding the association between OS and ejaculatory abstinence period, as well as the potential mechanisms involved in the pathophysiology of various systemic diseases such as obesity, insulin resistance, hypertension, and certain mental health disorders which have been shown to cause OS induced male infertility. Finally, special emphasis will be placed on the potential for transferring and incorporating research findings emanating from different experimental studies into clinical practice.