Prof. Ralf Henkel

Permanent URI for this collection

https://hdl.handle.net/10566/2094

Position:	Head of Department and Deputy Dean for Postgraduate Studies
Department:	Medical BioScience
Faculty:	Natural Sciences
Qualifications:	BEd, PhD, Habil
	My publications in this repository
Tel:	021 959 2332
Fax:	021 959 3125
Email:	rhenkel@uwc.ac.za

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Now showing 1 - 9 of 9

Bibliometrics: tracking research impact by selecting the appropriate metrics
(Medknow Publications, 2016) Henkel, Ralf
Traditionally, the success of a researcher is assessed by the number of publications he or she publishes in peer-reviewed, indexed, high impact journals. This essential yardstick, often referred to as the impact of a specific researcher, is assessed through the use of various metrics. While researchers may be acquainted with such matrices, many do not know how to use them to enhance their careers. In addition to these metrics, a number of other factors should be taken into consideration to objectively evaluate a scientist's profile as a researcher and academician. Moreover, each metric has its own limitations that need to be considered when selecting an appropriate metric for evaluation. This paper provides a broad overview of the wide array of metrics currently in use in academia and research. Popular metrics are discussed and defined, including traditional metrics and article-level metrics, some of which are applied to researchers for a greater understanding of a particular concept, including varicocele that is the thematic area of this Special Issue of Asian Journal of Andrology. We recommend the combined use of quantitative and qualitative evaluation using judiciously selected metrics for a more objective assessment of scholarly output and research impact.
Effect of the metabolic syndrome on male reproductive function: a case-controlled pilot study
(Wiley, 2014) Leisegang, Kristian; Bouic, Patrick J.D.; Henkel, Ralf
The metabolic syndrome (MetS) is a constellation of various risk factors. This study aimed to investigate the effect of MetS on testosterone and progesterone, and semen parameters, in a case-controlled pilot study. Male patients (n = 54) had body mass index, waist-to-hip ratio (WHR) and blood pressure recorded. Blood was analysed for HDL cholesterol, triglycerides and glucose. Saliva was assayed for free testosterone and free progesterone. Ejaculates were analysed for volume, sperm concentration, total sperm count, motility, vitality, mitochondrial membrane potential (MMP), DNA fragmentation and leucocyte concentration. Participants were divided into the control group (n = 28) and the MetS group (n = 26). Differences were found between the groups for body mass index, WHR, blood pressure, high-density lipoprotein (HDL), triglycerides and glucose. The MetS group showed significant reductions in sperm concentration (P = 0.0026), total sperm count (P = 0.0034), total motility (P = 0.0291), sperm vitality (P = 0.002), MMP (P = 0.0039), free testosterone (P = 0.0093) and free progesterone (P = 0.0130), while values for DNA fragmentation increased (P = 0.0287). Results indicate that patients with MetS have compromised sperm parameters in the absence of leucocytospermia. A reduction in free progesterone suggests that steroidogenesis cascades may be compromised. It is hypothesised that a systemic pro-inflammatory state with oxidative stress associated with MetS may provide a novel explanation.
Green nanotechnology as an innovative drug delivery approach for typha capensis and naringenin—new class of phytochemical embedded biocompatible gold nanoparticles in prostate cancer therap
(Journal of Drug Delivery Science and Technology, 2022) Henkel, Ralf; Pearce, Keenau
Naringenin, a flavone with a growing body of evidence as an anti-cancer agent, is found in Typha capensis, an indigenous South African plant commonly used in traditional medicine. However, despite favourable in vitro results, clinical usage of naringenin remains restricted due to notoriously poor oral bioavailability, rapid metabolism and poor tumour site availability. This study aimed to investigate a simple, easily reproduced, reliable and effective drug delivery method of mitigating these issues using green nanotechnology principles, and assess their biomedical applications in the treatment of prostate cancer. Gold nanoparticles (AuNPs) were synthesized using green nanotechnology principles and characterized by spectrophotometry, dynamic light scattering, zeta potential, transmission electron microscopy, and Folin-ciocalteu phenol assay.
Impact of body composition analysis on male sexual function: A metabolic age study
(Frontiers, 2023) Henkel, R
Metabolic Age (MetAge) and body composition analysis may reflect an individual’s metabolic status, which is believed to influence male sexual and gonadal functions. Although erectile dysfunction (ED) and hypogonadism are increasingly prevalent with age, they are also detected among younger men. This study aims to assess the impact of MetAge and body composition on male sexual and gonadal status overall, and particularly in men younger than 40 years of age.
The impact of Covid-19 vaccines on male semen parameters: A retrospective cohort study
(University of the Western Cape, 2023) Henkel, Ralf; Leisegang, Kristian; Finelli, Renata
The emergence of SARS-CoV-2 and the subsequent COVID-19 pandemic necessitated the development of adequate vaccines. Despite vaccines being demonstrated to be safe and effective for preventing severe disease and death, vaccine hesitancy remains. Reasons include concerns over adverse effects on male fertility, which have not been widely investigated. Therefore, this study is aimed at determining the impact of COVID-19 vaccination on semen parameters in a retrospective cohort study of South African males undergoing fertility assessment. The patients for this study were adult men who have previously undergone routine semen analysis for fertility assessment at Androcryos Andrology Laboratory (Johannesburg, South Africa) between March 2021 and March 2022. They also received vaccination within 3 months following a semen analysis and underwent a second semen analysis any time post-COVID-19 vaccination. From 277 records analysed, 46 patients met the inclusion criteria, receiving the Pfizer-BioNTech (BNT162b1) (63%), Johnson and Johnson (JNJ-78436735/Ad26.COV2S) (34.8%), and the AstraZeneca (AZD1222) (2.2%) vaccines. Sperm concentration significantly increased postvaccination (P = 0:0001), with no significant changes in semen pH, volume, total sperm count, progressive motility, normal sperm morphology, or chromatin condensation. Results were not influenced by age, type of vaccine received, and the number of days following vaccination, as depicted by multiple regression analysis. In conclusion, there is no evidence of a negative impact of COVID-19 vaccination on male semen parameters, which is consistent with the emerging literature on COVID-19 vaccination and male fertility. COVID-19 vaccinations should not be dismissed based on fear of adverse effects on male fertility parameters.
The impact of male overweight on semen quality and outcome of assisted reproduction
(Medknow Publications, 2014) Leisegang, Kristian; Henkel, Ralf
The impact of obesity on male reproductive health remains a contested topic as evidence is inconclusive and inconsistent. Even more debatable is the effect of male obesity in assisted reproduction. In the manuscript, “the impact of male overweight on semen quality and outcome of assisted reproduction” published in Asian Journal of Andrology, Thomsen et al. investigated the effect of male obesity on fertilization outcomes in intrauterine insemination, in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) programs further contributes to the increasing body of evidence in this field.
Inorganic ions in leonotis leonurus extract do not explain changes in isolated Wistar rat heart function
(Open Access Science Research Publisher, 2011) Burger, Andries; Mugabo, Pierre; Henkel, Ralf; Green, Ivan
Leonotis leonurus (L. leonurus) R. Br (Lamiaceae) is used by healers in South Africa. The present study was conducted to determine if the L. leonurus effect on isolated rat heart is due to ionic changes in the perfusion fluid.
Male age and progressive sperm motility are critical factors affecting embryological and clinical outcomes in oocyte donor ICSI cycles
(Reproductive Sciences, 2021) Henkel, Ralf
This retrospective cohort study aimed to explore whether paternal age and semen quality parameters affect the embryological and clinical outcomes of ICSI with oocyte donation. A total of 339 oocyte donation (OD)-ICSI cycles were categorized into four groups according to the semen parameter profiles of the male counterparts: normozoospermia (NS, n = 184), oligozoospermia (OS, n = 41), asthenozoospermia (AS, n = 50), and oligoasthenozoospermia (OAS, n = 64). The effect of age, total sperm count, and progressive motility was separately analyzed for reproductive outcomes and compared between the study groups: fertilization, blastulation, and top-quality embryo rate, biochemical and clinical pregnancy, live birth, and miscarriage. A negative correlation between male age and fertilization rate was observed (rs = - 0.23, p < 0.0001), while male age was a significant factor for biochemical pregnancy (p = 0.0002), clinical pregnancy (p = 0.0017), and live birth (p = 0.0038). Reduced total sperm count and lowered progressive motility led to poorer fertilization rates (rs = 0.19 and 0.35, respectively, p < 0.0001) and affected embryo quality (rs = 0.13, p = 0.02, and rs = 0.22, p < 0.0001, respectively). OD-ICSI cycles with asthenozoospermia had significantly lowered success rates in biochemical pregnancy, clinical pregnancy, and live birth (p < 0.05). Our study demonstrated that both advanced male age and reduced progressive motility of spermatozoa exert a significant negative influence on the outcome of assisted reproduction, even in controlled procedures with gamete selection and optimization such as in OD-ICSI. Improvement in treatment strategies and male fertility evaluation requires incorporation of such evidence to obtain better prognosis towards personalized management.
Obesity is associated with increased seminal insulin and leptin alongside reduced fertility parameters in a controlled male cohort
(BioMed Central, 2014) Leisegang, Kristian; Menkveld, Roelof; Bouic, Patrick J.D.; Henkel, Ralf
Obesity appears to be associated with male reproductive dysfunction and infertility, although this has been inconsistent and inconclusive. Insulin and leptin are known mediators and modulators of the hypothalamus-pituitary-testes axis, contributing to the regulation of male reproductive potential and overall wellbeing. These hormones are also present in semen influencing sperm functions. Although abdominal obesity is closely associated with insulin resistance (hyperinsulinaemia), hyperleptinaemia and glucose dysfunction, changes in seminal plasma concentrations of insulin, leptin and glucose in obese males has not previously been investigated.

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