Nico Claassen

Nico Claassen
University of Pretoria | UP · School of Health Systems and Public Health

Doctor of Philosophy

About

41
Publications
5,308
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789
Citations
Introduction
Nico Claassen currently works at the School of Health Systems and Public Health, University of Pretoria. Nico does research in Systems Biology, Physiology and Human Biology. Their most recent publication is 'Allostatic load and heart rate variability as health risk indicators'.

Publications

Publications (41)
Article
Full-text available
Background Health workers, in short supply in many low-and-middle-income countries, are at increased risk of SARS-CoV-2 infection. This study aimed to assess how South Africa, prepared to protect its health workers from SARS-CoV-2 infection. Methods This was a cross-sectional study design applying participatory action research in four provinces of...
Preprint
Full-text available
Background: Health workers, in short supply in many low-and-middle-income countries (LMICs), are at increased risk of SARS-CoV-2 infection during their employment. This study aimed to assess how South Africa, an LMIC, prepared to protect its health workers from SARS-CoV-2. Methods: This was a participatory mixed method study conducted in four provi...
Article
Full-text available
Background: Health workers are crucial to the successful implementation of infection prevention and control strategies to limit the transmission of SARS-CoV-2 at healthcare facilities. The aim of our study was to determine SARS-CoV-2 infection prevention and control knowledge and attitudes of frontline health workers in four provinces of South Afr...
Preprint
Full-text available
Background: Health workers are crucial to the successful implementation of infection prevention and control strategies to limit the transmission of SARS-CoV-2 at healthcare facilities. The aim of our study was to determine SARS-CoV-2 infection prevention and control knowledge and attitudes of frontline health workers in four provinces of South Afri...
Poster
Evaluation of exhaled carbon monoxide and carboxyhaemoglobin levels of forklift drivers operating in the Banana Ripening Centre of the Tshwane Fresh Produce Market.
Article
Background: Despite strong reservations regarding the validity of a number of heart rate variability (HRV) measures, these are still being used in recent studies. Aims: We aimed to compare the reactivity of ostensible sympathetic HRV markers (low and very low frequency [LF and VLF]) to that of electrodermal activity (EDA), an exclusively sympatheti...
Article
Full-text available
We examined the factors associated with mother-reported wheeze and dry cough in children living in Tembisa, a residential and industrial community in South Africa. A cross-sectional sample of parents reported wheezing and dry cough in children (aged 1 to 26 months) by completing the standardised International Study of Asthma and Allergies in Childh...
Article
Objective: A case study describing the association between vagal tone and social-emotional adaptation in two distressed adolescent–parent (A–P) pairs during a Positive Cognitive Behaviour Therapy Programme (P-CBTP). Methods: Two A–P pairs completed a P-CBTP with pre- and post-intervention biosocial-emotional assessments; weekly training sessions ov...
Article
Background: Uncertainty often exists about the comparability of results obtained by different health risk indicator systems. Objectives: To compare two health risk indicator systems, i.e, allostatic load and heart rate variability (HRV). Additionally, to investigate the feasibility of inclusion of HRV indicators into allostatic load assessments...
Article
Background: Cynicism, as a personality trait, has adverse effects on health. The question was asked whether cynical attitudes that develop due to work-related stress correlate with stress levels and whether it has a negative influence on health. Objectives: To investigate associations of the cynicism subscale scores of the Maslach Burnout Invent...
Article
Full-text available
Background: Coal tar-derived substances consist of numerous polycyclic aromatic hydrocarbons (PAHs), several of which are known carcinogens. Different processes used during steel making influence PAH release into the work environment. Furthermore, employees’ jobs and personal hygiene practices may influence personal PAH exposure. Objective: This st...
Article
BACKGROUND : Coal tar-derived substances consist of numerous polycyclic aromatic hydrocarbons (PAHs), several of which are known carcinogens. Different processes used during steel making influence PAH release into the work environment. Furthermore, employees’ jobs and personal hygiene practices may influence personal PAH exposure. OBJECTIVE : This...
Article
Full-text available
Background: A high prevalence of noise induced hearing loss (NIHL) is observed amongst employees in the steel manufacturing industry. Objective: To determine the prevalence of NIHL and current noise abatement techniques implemented at a steel manufacturing plant. Methods: Structured questionnaires were completed by permanent employees at a steel m...
Article
Full-text available
The WBGT index is the heat stress index of preference in the Occupational Health and Safety Act, No. 85 of 1993. The purpose of this investigation was to determine if equivalent WBGT values with low and high relative humidity levels would result in similar physiological heat loads. Un-acclimatised subjects were exposed to 24, 28, 30 and 32 WBGT wit...
Article
This study investigated the influence of skydiving and freefall, as well as that of visualisation, on the autonomic nervous system balance. The results showed a shift towards sympathetic dominance in the autonomic nervous system balance during skydiving and freefall. This shift was statistically significant in the inexperienced, but not in the expe...
Article
Full-text available
The purpose of this field study was to examine gender differences in the sweat response reported in the literature in trained men and women during indoor cycling. In the present study, 14 men and 12 women took part in a 90-minute spinning class in preparation for a 108-km road race. Delta body mass, corrected for the volume of water consumed, was u...
Article
The possibility of using Hsp70 and hsp70 gene polymorphisms as markers of acclimatization was investigated. Volunteers (22) were subjected to an acclimatization regimen and blood analysed for Hsp70 (Hsp72) and hsp70 polymorphisms before and after a heat tolerance test. Physiological parameters denoting acclimatization, or not, were correlated to le...
Article
Background Sudden cardiac death related to exercise is an uncommon problem, but is perhaps the single biggest challenge to sports medicine practitioners. Although the overall risk of death due to cardiac causes is substantially reduced in those who exercise regularly, the risk is temporarily increased during exercise. The causes of sudden cardiac d...
Article
Full-text available
Objective. This study investigated the effects of single dosages of the non-steroidal anti-inflammatory drug (NSAID) naproxen, and of the coxib, rofecoxib, on the exercise-induced stress response. Design. Eight subjects (age 20.9 ± 1.1 years, weight 70.4 ± 3.9 kg, height 170.9 ± 6.7 cm, body surface area 1.82 ± 0.09 m2, body mass index 24.1 ± 1.3 k...
Article
Full-text available
Objective. This study investigated the effects of single dosages of the non-steroidal anti-inflammatory drug (NSAID) naproxen, and of the coxib, rofecoxib, on the exercise-induced stress response. Design. Eight subjects (age 20.9 ± 1.1 years, weight 70.4 ± 3.9 kg, height 170.9 ± 6.7 cm, body surface area 1.82 ± 0.09 m2, body mass index 24.1 ± 1.3 k...
Article
Polyunsaturated fatty acids (PUFAs) as well as oestrogen (E2) and parathyroid hormone (PTH) affect bone cells. The aim of the study was to determine whether arachidonic acid (AA), E2, and PTH increase prostaglandin E(2) (PGE(2)) synthesis in MG-63 and MC3T3-E1 osteoblastic cells and the level of mediation by COX-1 and COX-2. PGE(2) levels were dete...
Article
Dietary supplementation with fish oil that contains omega-3 polyunsaturated fatty acids has been shown to enhance bone density as well as duodenal calcium uptake in rats. The latter process is supported by membrane ATPases. The present in vitro study was undertaken to test the effect of omega-3 fatty acids on ATPase activity in isolated basolateral...
Article
Dietary supplementation with fish oil that contains omega-3 polyunsaturated fatty acids has been shown to enhance bone density as well as duodenal calcium uptake in rats. The latter process is supported by membrane ATPases. The present in vitro study was undertaken to test the effect of omega-3 fatty acids on ATPase activity in isolated basolateral...
Article
Duodenal ion transport processes are supported by ATPase enzymes in basolateral membranes of the enterocyte. In vivo studies have shown that long term n-6 poly-unsaturated fatty acid (PUFA) supplementation in rats causes increases in intestinal Ca absorption, coupled with a higher total calcium balance and bone calcium content. The present in vitro...
Article
Essential fatty acid deficient animals develop osteoporosis. Eicosapentaenoic acid and gamma-linoleic acid have been reported to have positive effects on bone metabolism in both the growing male rat and the ovariectomized (OVX) female rat. These effects have been further investigated using a novel gamma-linolenic/eicosapentaenoic acid diester toget...
Article
Supplementation with essential fatty acids has been shown to prevent the experimentally induced ectopic calcification of the kidneys known as nephrocalcinosis. Male Sprague-Dawley rats were fed a semi-synthetic diet supplemented with different essential fatty acids while being injected for a period of 10 days with calcium glubionate. After 3 weeks...
Article
There are two types of essential fatty acids (EFAs), the n-6 derived from linoleic acid (LA) and the n-3, derived from alpha-linolenic acid (ALA). Most of the functions of the EFAs require the conversion of LA and ALA to their metabolites including, gammalinolenic (GLA), dihomogammalinolenic (DGLA), arachidonic (AA) (n-6) and eicosapentaenoic (EPA)...
Article
The precise interaction of oestrogens and their receptors in relation to Ca2+ absorption in the small intestine is still unclear. The object of this investigation was therefore to investigate the presence of functional oestrogen receptors in the duodenum of female BD9 rats. The classic radioligand binding procedure was used to ascertain the ER stat...
Article
Intestinal calcium uptake follows both a saturable and a non-saturable uptake route. The saturable route is energy-dependent. Ca2+-Mg2+-ATPase is mainly responsible for extrusion of calcium from the intestinal enterocyte. Saturable intestinal calcium uptake declines significantly in the rat from 42 days of age until 84 days of age. Similar changes...
Article
Full-text available
Significant changes in saturable and non-saturable intestinal calcium uptake processes occur during development of the rat. A modified 'free floating disc' assay was used to measure total, active and passive duodenal calcium uptake on matching duodenal segments from male Sprague Dawley rats aged 14 to 56 days of age. The results were compared and f...
Article
Prostaglandins (PGs) are known to have various effects on bone metabolism. The supplementation of essential fatty acids (EFAs), the precursors of PGs, leads to increased intestinal calcium absorption and calcium balance. It is, however, not known whether increased calcium absorption and calcium balance will enhance the calcium content in bone. Male...
Article
The effect of different ratios of the prostaglandin precursors gamma-linolenic (GLA) and eicosapentaenoic (EPA) acids on bone status in growing rats measured as a function of free urinary pyridinium crosslinks and hydroxyproline levels was investigated. Male Sprague-Dawley rats were weaned onto an essential fatty acid deficient diet and from their...
Article
Sprague Dawley rats were supplemented with either fish oil, evening primrose oil or sunflower oil (control) for 12 weeks. Calcium balance and fatty acid analyses of plasma and intestinal membranes were performed at week 12. Fish oil decreased faecal calcium excretion significantly leading to an increased calcium balance (p < 0.05). Increased unsatu...
Article
Intestinal calcium transport is important in whole body calcium homeostasis and it is therefore of interest to understand the mechanism of absorption and its regulation by 1;25-dihydroxyvitamin D3 (1,25 (OH)2D3) (vitamin D). Significant changes in lipid composition of membranes have previously been shown in response to vitamin D3 administration. De...
Article
Skripsie (MSc)--PU vir CHO, 1989. Bibliografie: blaaie 73-79.

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Projects

Projects (3)
Archived project
Archived project
To explore the neighbourhood level variation of childhood asthma in an air pollution hotspot in South Africa. To explore factors associated with use of asthma medication among children diagnosed with asthma. To determine the prevalence of asthma respiratory symptoms among 3 month old babies exposed to air pollution during pregnancy . To determine if ARS in these babies persist during 9 months and 18-months of age.