SUNScholar - Browsing by Author "Du Plessis, Stefan S."

Browsing by Author "Du Plessis, Stefan S."

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Ameliorative potentials of quercetin against cotinine-induced toxic effects on human spermatozoa
(Hainan Medical University Journal Publisher, 2016) Goss, Dale; Oyeyipo, Ibukun P.; Skosana, Bongekile T.; Ayad, Bashir M.; Du Plessis, Stefan S.
Objectives: Cotinine, the principal metabolite of nicotine found in smokers' seminal plasma, has been shown to adversely affect sperm functionality while quercetin, a flavonoid with diverse properties is associated with several in vivo and in vitro health benefits. The aim of this study was to investigate the potential benefits of quercetin supplementation against damage caused by the by-products of tobacco smoke in human sperm cells. Methods: Washed human spermatozoa from 10 normozoospermic donors were treated with nutrient medium (control), quercetin (30 mmol/L) and cotinine (190 mg/mL, 300 ng/mL) with or without quercetin for 60 and 180 min incubation periods. Computer-aided sperm analysis was used to assess sperm motility while acrosomereacted cells were identified under a fluorescent microscope using fluorescein isothiocyanate-labelled Pisum Sativum Agglutinin as a probe, viability was assessed by means of a dye exclusion staining technique (eosin/nigrosin) and oxidative stress by flow cytometry using dihydroethidium as a probe. Values were expressed as mean ± S.E.M. as compared by ANOVA. Results: Higher cotinine concentrations reduced the number of viable cells after 60 and 180 min of exposure while viability of cells was increased in the cotinine aliquots supplemented with quercetin after 180 min of exposure when compared with cotinine only treated group. Conclusion: This study indicates that the ameliorating ability of quercetin on cotinineinduced decline in sperm function is associated with increased number of viable cells.
Cryopreservation/transplantation of ovarian tissue and in vitro maturation of follicles and oocytes : challenges for fertility preservation
(BioMed Central, 2008-10) Varghese, Alex C.; Du Plessis, Stefan S.; Falcone, Tommaso; Agarwal, Ashok
Cryopreservation of ovarian tissue and in vitro follicle maturation are two emerging techniques for fertility preservation, especially in cancer patients. These treatment regimes are opening up more options and allow for more suitable choices to preserve fertility according to the patient's specific circumstances. If these technologies are to become widely accepted, they need to be safe, easy to perform and must obtain favorable results. The generation of healthy eggs with the normal genetic complement and the ability to develop into viable and healthy embryos requires tight regulation of oocyte development and maturation. Novel freezing techniques such as vitrification, along with whole ovary cryopreservation and three-dimensional follicle cultures, have shown favorable outcomes. The scope of this article is to take a comprehensively look at the challenges still faced in order for these novel technologies to be routinely employed with the aim of successful fertility preservation.
Diabetes mellitus and male infertility
(Medknow, 2018) Omolaoye, Temidayo; Du Plessis, Stefan S.
ENGLISH ABSTRACT: Infertility is prevalent in about 10%-25% of couples in their reproductive age, analogous to 60-80 million infertile couples globally. Of these infertility cases, 10%-30% are exclusively attributed to a problem of the male. Several diseases have been implicated as contributors to deteriorating male fertility and diabetes mellitus (DM) is included. DM, a chronic noncommunicable disease, has been considered as one of the most appreciable health threats, as it affects 9% (422 million) of the world’s population as of 2014. It is characterised by hyperglycaemia, which can result from the inability of the pancreatic毬-cells to secrete insulin or from the target tissue becoming insensitive to insulin. DM has been reported to influence male reproductive function through diverse pathways and mechanisms. The adverse effects of reactive oxygen species and successive development of oxidative stress that occur due to DM have been investigated and implicated by several studies. The products of nonenzymatic glycosylation are reported to be widely distributed in the reproductive tract of diabetic men. Additionally, DM has been implicated to impair the processes of male sexual acts. Data reported in this review were extracted from PubMed, Google Scholar, Science Direct and Scopus with diabetes and male infertility as the key search words. In light of the aforementioned, the aim of this review is to provide brief background information on DM as well highlight and explain the likely mechanisms of male fertility which DM impacts.
Highly active antiretroviral therapy alters sperm parameters and testicular antioxidant status in diet-induced obese rats
(Korean Society of Toxicology, 2018) Oyeyipo, Ibukun P.; Skosana, Bongekile T.; Everson, Frans P.; Strijdom, Hans; Du Plessis, Stefan S.
The efficacy of highly active antiretroviral therapy (HAART) has led to an increase demand for therapeutic use, thereby necessitating investigation into drug toxicity. This study was designed to investigate the in vivo effects of HAART on sperm parameters and testicular oxidative stress in lean and obese rats. Wistar rats (males, n = 40, weighing 180~200 g) were assigned randomly into 4 groups and treated accordingly for 16 weeks as follows: Control (C): lean group fed with standard rat chow; Diet induced obesity (DIO): obese animals fed a high caloric diet; C + ART: lean animals treated with HAART; DIO + ART: obese animals treated with HAART. An antiretroviral drug combination of Tenofovir, Emtricitabine and Efavirenz at a dose of 17, 26 and 50 mg/kg/day was administered for the latter 6 weeks via jelly cube feeding. At the end of the experimental period, sperm analysis was performed on sperm collected from the caudal epididymis, while the testis was homogenized for antioxidant enzyme and lipid peroxidation assays. Results showed that HAART significantly decreased sperm motility (p < 0.05) in both lean and obese animals, and viability (p < 0.05) in the DIO group. Testicular glutathione, catalase and superoxide dismutase were significantly decreased (p < 0.05), while Thiobarbituric acid reactive substances (TBARS) levels were significantly increased (p < 0.05) when the DIO+ART group was compared to Control group. Thus, the decreased sperm qualities associated with HAART might be as a result of increased testicular oxidative stress prominent in obese animals.
Influence of ejaculation frequency on seminal parameters
(BioMed Central, 2015-05-21) Mayorga-Torres, B. Jose Manuel; Camargo, Mauricio; Agarwal, Ashok; Du Plessis, Stefan S.; Cadavid, Angela P.; Maya, Walter D. Cardona
Background: Several factors have been shown to influence semen parameters, one of which is sexual abstinence; a clinical criteria included in the semen evaluation to provide maximum sperm quality. The aim of the present study was to assess the effect of a daily ejaculation frequency on conventional and functional semen parameters. Methods: Semen samples were collected daily over a period of two weeks of which every second sample per person was processed and analyzed according to the World Health Organization guidelines. Furthermore, mitochondrial function, intracellular reactive oxygen species production and sperm DNA fragmentation were evaluated by flow cytometry. Results: Total sperm count and seminal volume per ejaculation declined and remained decreased for the duration of the daily ejaculation period. However, conventional parameters such as sperm concentration, motility, progressive motility, morphology, vitality and functional parameters such as sperm plasma membrane integrity, mitochondrial membrane potential and DNA fragmentation was not significantly affected and remained similar to the initial measurement throughout the daily ejaculation period. Despite intra- and inter individual variations, the average values of the basic semen parameters remained above the WHO (2010) reference values throughout the daily ejaculation period. Interestingly, a decreasing trend in intracellular ROS production was observed, although statistically not significant. Conclusions: The study shows that an extended 2 week period of daily ejaculation does not have major clinical effects on conventional and functional seminal parameters.
Modulation of inflammatory cytokines and islet morphology as therapeutic mechanisms of Basella alba in streptozotocin-induced diabetic rats
(Korean Society of Toxicology, 2018) Arokoyo, Dennis S.; Oyeyipo, Ibukun P.; Du Plessis, Stefan S.; Chegou, Novel N.; Aboua, Yapo G.
The mechanism of the previously reported antidiabetic effect of Basella alba is unknown. This study investigated the role of B. alba aqueous leaf extract in the modulation of inflammatory cytokines and islet morphology in streptozotocin-induced diabetic rats. Forty male Wistar rats, between 8 and 10 weeks old, were randomly divided into four groups (n = 10) and administered the following treatments: Healthy control (H-c) and Diabetic control (D-c) animals received normal saline 0.5 mL/100 g body weight daily, while Healthy Treatment (H-Ba) and Diabetic Treatment (D-Ba) rats received the plant extract 200 mg/kg body weight daily. All treatments were administered by oral gavage. Diabetes was induced in D-c and D-Ba rats by a single intraperitoneal injection of streptozotocin (55 mg/kg body). The body weight and fasting blood sugar (FBS) levels were recorded every week for 4 weeks, after which the rats were euthanized and samples collected for further analysis. After the experiment, FBS level was significantly reduced (p < 0.0001) in rats in the D-Ba group, but increased (p < 0.001) in rats in the D-c group. The absolute (H-c and H-Ba vs D-c, p < 0.05) and relative (D-Ba vs H-c, p < 0.05; D-Ba vs H-Ba, p < 0.005) weights of the pancreases were significantly higher after the experiment. The rats in the D-c group had significantly higher levels of serum interleukin-1β (p < 0.001 vs H-c; p < 0.05 vs H-Ba and D-Ba) and monocyte chemotactic protein-1 (p < 0.0001), but lower levels of interleukin-10 (p < 0.05) in comparison with the other groups. Histopathological examination revealed severe interstitial congestion, reduced islet area (p < 0.0001), and increased islet cell density in the D-c group compared with those in the D-Ba group. From these findings, it was concluded that the aqueous extract of B. alba stimulates the recovery of beta-islet morphology in streptozotocininduced diabetic rats by modulating the peripheral production of inflammatory cytokines.
Physically active men show better semen parameters than their sedentary counterparts
(Royan Institute, 2017) Lalinde-Acevedo, Paula C.; Mayorga-Torres, B. Jose Manuel; Agarwa, Ashok; Du Plessis, Stefan S.; Ahmad, Gulfam; Cadavid, Angela P.; Maya, Walter D. Cardona
Background: The quality of semen depends upon several factors such as environment, life style, physical activity, age, and occupation. The aim of this study was to analyze and compare the conventional and functional semen parameters in men practicing vigorous physical activity to those of sedentary men. Materials and Methods: In this descriptive cross-sectional study, semen samples of 17 physically active men and 15 sedentary men were collected for analysis. Semen analysis was performed according to the World Health Organization (WHO) guidelines, while functional parameters were evaluated by flow cytometry. Results: Results showed that several semen parameters (semen volume, viability, progressive motility, total motility, normal morphology, and moribund cells) were superior in the physically active group in comparison with the sedentary group. Semen parameters such as viability, progressive motility and total motility, as well as the percentage of moribund spermatozoa were significantly different between both groups. However, sperm DNA damage, lipid peroxidation and mitochondrial potential were not significantly different among the groups. Conclusion: Nevertheless, the physical activity shows better semen parameters than sedentary group. Taken together, our results demonstrate that regular physical activity has beneficial impact in sperm fertility parameters and such a life style can enhance the fertility status of men.
Proteomic analysis of seminal fluid from men exhibiting oxidative stress
(BioMed Central, 2013-09) Sharma, Rakesh; Agarwal, Ashok; Mohanty, Gayatri; Du Plessis, Stefan S.; Gopalan, Banu; Willard, Belinda; Yadav, Satya P.; Sabanegh, Edmund
ABSTRACT: Background: Seminal plasma serves as a natural reservoir of antioxidants. It helps to remove excessive formation of reactive oxygen species (ROS) and consequently, reduce oxidative stress. Proteomic profiling of seminal plasma proteins is important to understand the molecular mechanisms underlying oxidative stress and sperm dysfunction in infertile men. Methods This prospective study consisted of 52 subjects: 32 infertile men and 20 healthy donors. Once semen and oxidative stress parameters were assessed (ROS, antioxidant concentration and DNA damage), the subjects were categorized into ROS positive (ROS+) or ROS negative (ROS-). Seminal plasma from each group was pooled and subjected to proteomics analysis. In-solution digestion and protein identification with liquid chromatography tandem mass spectrometry (LC-MS/MS), followed by bioinformatics analyses was used to identify and characterize potential biomarker proteins. Results A total of 14 proteins were identified in this analysis with 7 of these common and unique proteins were identified in both the ROS+ and ROS- groups through MASCOT and SEQUEST analyses, respectively. Prolactin-induced protein was found to be more abundantly present in men with increased levels of ROS. Gene ontology annotations showed extracellular distribution of proteins with a major role in antioxidative activity and regulatory processes. Conclusions We have identified proteins that help protect against oxidative stress and are uniquely present in the seminal plasma of the ROS- men. Men exhibiting high levels of ROS in their seminal ejaculate are likely to exhibit proteins that are either downregulated or oxidatively modified, and these could potentially contribute to male infertility.
Proteomics : a subcellular look at spermatozoa
(BioMed Central, 2011-03) Du Plessis, Stefan S.; Kashou, Anthony H.; Benjamin, David J.; Yadav, Satya P.; Agarwal, Ashok
Abstract. Background. Male-factor infertility presents a vexing problem for many reproductively active couples. Many studies have focused on abnormal sperm parameters. Recent advances in proteomic techniques, especially in mass spectrometry, have aided in the study of sperm and more specifically, sperm proteins. The aim of this study was to review the current literature on the various proteomic techniques, and their usefulness in diagnosing sperm dysfunction and potential applications in the clinical setting. Methods Review of PubMed database. Key words: spermatozoa, proteomics, protein, proteome, 2D-PAGE, mass spectrometry. Results. Recently employed proteomic methods, such as two-dimensional polyacrylamide gel electrophoresis, mass spectrometry, and differential in gel electrophoresis, have identified numerous sperm-specific proteins. They also have provided a further understanding of protein function involved in sperm processes and for the differentiation between normal and abnormal states. In addition, studies on the sperm proteome have demonstrated the importance of post-translational modifications, and their ability to bring about physiological changes in sperm function. No longer do researchers believe that in order for them to elucidate the biochemical functions of genes, mere knowledge of the human genome sequence is sufficient. Moreover, a greater understanding of the physiological function of every protein in the tissue-specific proteome is essential in order to unravel the biological display of the human genome. Conclusion Recent advances in proteomic techniques have provided insight into sperm function and dysfunction. Several multidimensional separation techniques can be utilized to identify and characterize spermatozoa. Future developments in bioinformatics can further assist researchers in understanding the vast amount of data collected in proteomic studies. Moreover, such advances in proteomics may help to decipher metabolites which can act as biomarkers in the detection of sperm impairments and to potentially develop treatment for infertile couples. Further comprehensive studies on sperm-specific proteome, mechanisms of protein function and its proteolytic regulation, biomarkers and functional pathways, such as oxidative-stress induced mechanisms, will provide better insight into physiological functions of the spermatozoa. Large-scale proteomic studies using purified protein assays will eventually lead to the development of novel biomarkers that may allow for detection of disease states, genetic abnormalities, and risk factors for male infertility. Ultimately, these biomarkers will allow for a better diagnosis of sperm dysfunction and aid in drug development.
Revisiting the relationship between the ejaculatory abstinence period and semen characteristics
(Royan Institute, 2018) Ayad, Bashir M.; Van der Horst, Gerhard; Du Plessis, Stefan S.
ENGLISH ABSTRACT: Variation in the ejaculatory abstinence period suggested by different guidance bodies have resulted in a growing concern among researchers and clinicians over what the precise period of ejaculatory abstinence ought to be for an optimal semen sample. Several studies have thus been undertaken to examine the association between the length of sexual abstinence and semen characteristics. Not all studies, however, have arrived at the same conclusions. This study aims to review all existing literature published during the past few decades pertaining to the influence of ejaculatory abstinence on semen quality. For the purpose of this systematic review, all data related to sexual abstinence duration and seminal parameters were re-analysed to homogenize the current data. Thorough PubMed, MEDLINE and Google Scholar, a literature search was conducted using the keywords “sexual abstinence”, “ejaculatory abstinence”, “semen”, “spermatozoa”, “semen analysis”, “sperm parameters”, “motility”, “reactive oxygen species (ROS)” and “DNA fragmentation”. After carefully reviewing all the literature, 30 relevant papers, both written in English and published between January 1979 and December 2016, were included in this review. The weight of the evidence suggests that the decline in semen volume and sperm concentration with shorter abstinence periods is accompanied by a substantial improvement in sperm motility characteristics, especially progressive motility and velocity. Nevertheless, available data are insufficient to support definitive conclusions regarding the influence of the ejaculatory abstinence period on advanced semen parameters (ROS, DNA fragmentation and seminal plasma antioxidant capacity) and pregnancy rates. In conclusion, taking all data into account, shortening of the abstinence period may be beneficial to sperm quality. Furthermore, we recommend that the current guidelines regarding the prescribed abstinence period should be revisited.
Spermatozoa : a historical perspective
(Royan Institute, 2018) Suarez, Jenniffer Puerta; Du Plessis, Stefan S.; Maya, Walter D. C.
ENGLISH ABSTRACT: The 100,000th scientific article on the subject of spermatozoa was recently published. Numerous studies evaluated the characteristics of this important cell that led to tremendous discoveries. Since its first observation and description in 1677, many important characteristics have been described regarding this highly fascinating gamete. In this review, we intend to provide a historical account of the numerous milestones and breakthroughs achieved related to sperma- tozoa. We conducted a review of the literature by selecting the most important subjects with regards to spermatozoa. Since their discovery by van Leeuwenhoek, spermatozoa have been studied by scientists to better understand their physiology and process of interaction with their female counterpart, the oocyte, in order to treat and resolve infertility problems. Three centuries after van Leeuwenhoek’s discovery, the 100,000th article about these cells was published. It is encouraging that sperm research reached this landmark, but at the same time it is clear that further research on male reproductive physiology and spermatozoa is required to shed more light on their function and pathology in order to reduce the number of unexplained infertility cases.
Utility of antioxidants during assisted reproductive techniques : an evidence based review
(BioMed Central, 2014-11-24) Agarwal, Ashok; Durairajanayagam, Damayanthi; Du Plessis, Stefan S.
Assisted reproductive technology (ART) is a common treatment of choice for many couples facing infertility issues, be it due to male or female factor, or idiopathic. Employment of ART techniques, however, come with its own challenges as the in vitro environment is not nearly as ideal as the in vivo environment, where reactive oxygen species (ROS) build-up leading to oxidative stress is kept in check by the endogenous antioxidants system. While physiological amounts of ROS are necessary for normal reproductive function in vivo, in vitro manipulation of gametes and embryos exposes these cells to excessive ROS production either by endogenous or exogenous environmental factors. In this review, we discuss the sources of ROS in an in vitro clinical setting and the influence of oxidative stress on gamete/embryo quality and the outcome of IVF/ICSI. Sources of ROS and different strategies of overcoming the excessive generation of ROS in vitro are also highlighted. Endogenously, the gametes and the developing embryo become sources of ROS. Multiple exogenous factors act as potential sources of ROS, including exposure to visible light, composition of culture media, pH and temperature, oxygen concentration, centrifugation during spermatozoa preparation, ART technique involving handling of gamete/embryo and cryopreservation technique (freeze/thawing process). Finally, the use of antioxidants as agents to minimize ROS generation in the in vitro environment and as oral therapy is highlighted. Both enzymatic and non-enzymatic antioxidants are discussed and the outcome of studies using these antioxidants as oral therapy in the male or female or its use in vitro in media is presented. While results of studies using certain antioxidant agents are promising, the current body of evidence as a whole suggests the need for further well-designed and larger scale randomized controlled studies, as well as research to minimize oxidative stress conditions in the clinical ART setting.

Browsing by Author "Du Plessis, Stefan S."

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