Masters Degrees (Medical Physiology)

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Browsing Masters Degrees (Medical Physiology) by browse.metadata.advisor "Du Plessis, Stefan S."

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    Changes in hyo-laryngeal elevation post-pharyngeal electrical stimulation
    (Stellenbosch : Stellenbosch University, 2015-04) Basson, Tobias Johannes; Pillay, Mershen; Du Plessis, Stefan S.; Stellenbosch University. Faculty of Health Sciences. Dept. of Biomedical Sciences. Medical Physiology.
    ENGLISH ABSTRACT: Swallowing disorders are prevalent in many elderly individuals and are common amongst individuals suffering from neurological diseases. These individuals are affected from slight swallowing difficulty to total swallowing inability. In severe cases this may cause aspiration pneumonia, dehydration, malnutrition and ultimately death. Swallowing disorders can be diagnosed and treated to increase quality of life. New treatment strategies to understand the pathophysiology and impaired swallowing response are needed. Neuromuscular electrical stimulation is used as rehabilitation method in various disciplines. This method of rehabilitation of physiological dysfunction is used in treating swallowing disorders and has become a focus for current research. To understand the effect of electrical stimulation to the swallowing centre it is proposed to study its mechanism on normal swallowing musculature. The outcome of the effect that electrical stimulation has on healthy individuals may possibly be used to extrapolate to clinical settings and its benefit for modern dysphagia rehabilitation. The purpose of this study was to report on the hyo-laryngeal movement pattern of young healthy, male and female, individuals and to measure the effect of a single neuromuscular electrical stimulation session on the hyo-laryngeal complex of 22 young healthy individuals. Lastly, the aim was to determine the detraining or lasting effect on the hyo-laryngeal swallowing complex of a single neuromuscular electrical stimulation session. The study reported on baseline hyo-laryngeal complex movement patterns by measuring the anterior movement and elevation of the hyo-laryngeal complex through the use of videofluoroscopy swallow study. Analysis of these measurements where done to report on the effect of electrical stimulation on the hyo-laryngeal complex movement pattern pre- and post- electrical stimulation. Significant changes were revealed with elevation of the hyo-laryngeal complex, however no significant effects could be found with anterior movement of the hyo-laryngeal complex pre- and post- electrical stimulation. It was found that elevation of the hyo-laryngeal complex lowered after a single electrical stimulation session. The hyo-laryngeal complex movement pattern remained similar between genders. Lastly it was found that a single electrical stimulation session showed significant reversibility towards baseline levels. This might be related to muscle fatigue and one would need to take into account muscle recovery for future research.
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    Observing the Effects of Anxiety Levels on Male Reproductive Parameters
    (Stellenbosch : Stellenbosch University, 2019-12) De Jager, Terri-Ann Lenice; Du Plessis, Stefan S.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Medical Physiology.
    ENGLISH ABSTRACT: Literature presents a complex and often contradictory picture of the link between psychological stress and male fertility. Very limited information is available on the specific relationship between anxiety level and male fecundity. University students, when compared to the general population, exhibit signs of decreased mental health, with students having increased prevalence of depression, anxiety, psychosis and addictions. The aim of the study was to determine if there is a relationship between anxiety and reproductive parameters in a male student model and what that relationship is. Twenty-one male participants between the ages of 20 and 25 were recruited as a part of this study. Participants were asked to donate at 4 different time-points. At each time-point, a semen sample and blood sample were collected and a State Trait Anxiety Inventory questionnaire was filled in. A semen analysis, presented in a spermiogram report, was performed using computer-aided sperm analysis to gather information about the basic semen parameters e.g. sperm concentration, sperm motility and sperm kinematics. The percentage fragmented sperm DNA, sperm nitric oxide level and semen reactive oxygen species levels were investigated. The cytokine profile and cortisol level were investigated in both the seminal plasma and blood plasma. The student population observed in this study displayed increased anxiety levels when considering their state (39.0, SD=13.69, n=83) and trait (43.0, SD=12.55, n=83) anxiety scores, respectively. Blood plasma cortisol levels were noted to increase as state and trait scores increased. Cortisol was thought to have an overall immuno-suppressant effect both locally, in the reproductive tract, as well as systemically. Round cells were positively correlated to blood plasma cortisol levels and trait anxiety levels. Throughout the study it was observed that average path velocity (VAP) and straight-line index (STR) kinematic parameters decreased as state anxiety scores, trait anxiety scores and blood plasma cortisol levels increased. An inverse relationship between total motility and trait anxiety was observed. The inverse relationship observed between elevated blood plasma cortisol and decreased spermatozoa viability and spermatozoa motility parameters is possibly a function of the increased number of round cells observed during this study. These findings suggest a possible role for increased anxiety or psychological stress to elucidate idiopathic infertility by means of affecting the cytokine profile. The increase in number of round cells in this study could therefore be a result of increased release of immature germ cells from a compromised blood-testis barrier. The changes in the cytokine profile, round cells in the semen and sperm motility often correspond to values observed in men presenting with idiopathic infertility. It can be concluded from this study that an increase in anxiety levels were found to have a negative relationship with male reproductive parameters.
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    Short abstinence: Impact on the seminal plasma proteome and accessory sex gland secretions
    (Stellenbosch : Stellenbosch University, 2018-03) Goss, Dale Mark; Du Plessis, Stefan S.; Van der Horst, Gerhard; Stellenbosch University. Faculty of Health Sciences. Dept. of Biomedical Sciences : Medical Physiology.
    ENGLISH ABSTRACT: Various studies have sought to determine the typical versus optimal abstinence period after which semen samples should be collected, and many have been found to be contradictory. Several factors influence the semen microenvironment and subsequent sperm basic and functional parameters. In this study we focused on important biomarkers of prostate, seminal vesicle and epididymal secretion. Furthermore, extensive proteomic analysis of seminal plasma was performed for a more comprehensive understanding of the observations. Semen samples were obtained from normozoospermic donors (n = 16) after 4 days and 4 hours of ejaculatory abstinence (EA) and standard semen analysis was performed with the assistance of computer aided sperm analysis (CASA), while the seminal plasma citric acid, neutral alpha-glucosidase and fructose concentrations were measured photometrically with commercially available assay kits. Protein identification was performed using advanced mass spectrometric techniques and pathways were analysed on both Reactome and String databases. Results of this study displayed significant decreases in semen volume, sperm concentration, total sperm count, and pH after 4 hours of ejaculatory abstinence when compared to 4 days. Furthermore, increases in total sperm motility and progressive motility after short EA periods were observed, accompanied by significant reductions in all epididymal and accessory sex gland biomarker concentrations. However, due to the decreased sperm number, these concentrations translated to a significant increase in citric acid and a decrease in fructose available per spermatozoon, which, along with the effects on semen pH, could more than likely be responsible for increased metabolic function and subsequent increase in the available energy for sperm motility. Proteomic analysis identified 22 differentially expressed seminal plasma proteins, with 18 proteins upregulated after 4 days of EA and 3 upregulated after 4 hours of EA. Of the proteins differentially expressed, 5 proteins from 4 days of EA and 2 proteins from 4 hours of EA, were identified to be related to sperm function and thus selected for pathway analysis. proteins were found to be prominent components of cellular processes including metabolism, apoptosis and cell process regulation, which can be linked directly and indirectly to sperm motility parameters. To conclude, the mechanisms by which very short EA improves sperm motility depends on seminal plasma composition thereby affecting metabolic function and protein interactions.