3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Motor development in six to seven year old children with identified intrinsic barriers to learning: a cross-sectional study(2017) Marsh, RichardBackground: Research has proven that conditions such as developmental coordination disorder (DCD) and attention deficit hyperactivity disorder (ADHD) are becoming more prevalent in children of school going age and that children presenting with these conditions have intrinsic barriers to learning. ADHD has been found in 3-5% of children. A 2001 census in South Africa showed 12% of the population had intellectual disabilities and 7% communication problems. A 2011 South African census show 3, 2% of the South African population aged five and above has mild concentration/remembering difficulties. When a child has poor performance, this can cause low self-esteem, poor social functioning, risk of obesity and vascular disease. The comorbidity between DCD and ADHD has been considered at a rate of 50%. Aim: The aim of this study was to determine whether children with intrinsic barriers to learning have specific motor development deficits. Method: There were 27 participants assessed using the Movement Assessment Battery for Children second version (M-ABC 2). The children were recruited from a private remedial school in Honeydew, South Africa and were identified as having intrinsic barriers to learning. The assessment looked at Aiming and Catching, Balance and Manual Dexterity. Each participant was assessed once. These results were analysed by looking at the prominent deficit and correlation to demographics or conditions. An ANOVA analysis was done to compare the different between conditions to Aiming and Catching, Balance and Manual Dexterity. Results: There were 10 females and 17 male children enrolled in the study. The mean age was seven years three months and fourteen days. The standard deviation of age was ±140.6 days. The most common diagnosis was ADHD (48%) followed by speech problems (33%). The Manual Dexterity mean score was 7.82 (± 2.22), the Aiming and Catching mean score was 9.78 (± 3.28) and the Balance mean score was 7.59 (± 2.91). The total mean score for the M-ABC was 7.63 (± 2.84). Manual dexterity and Balance scores were both significantly lower than the Aiming and Catching scores (p=0.02 and p=0.01, respectively). The results indicated no significant difference between the Manual Dexterity and Balance scores (p= 0.55). The ANOVA analysis showed that children with speech problems scored slightly higher in Manual Dexterity than children with anxiety problems and processing problems but this difference was not significant (p=0.52). Children with ADHD and speech problems appeared to score slightly higher in Aiming and Catching than children with anxiety problems and processing problems but this was not significantly different (p=0.15). Children with processing problems scored significantly higher (p=0.03) in Balance than children with the other conditions. Conclusion: Children who have intrinsic barriers to learning have been recognised to have motor deficits that fall into the diagnosis of DCD. It is important to assess these children to optimise their intervention program; not just from a cognitive aspect but from a motor aspect as well. The results of this study found that Manual Dexterity and Balance are motor components that were the most affected. Addressing these aspects may help improve the activity levels and participation of these children.Item An approach to the physiology of appetite.(1964) De Caire, EdwinItem The influence of slaughter on blood composition in cattle(University of the Witwatersrand, 1986-04-01) Riekert, Sydney PeterIn this study the effects of blood sampling, transportation and slaughter on certain blood variables (sodium, potasium, chloride, glucose, lactates, lipids, proteins, colloidal osmotic pressure, cortisol, ACTH, T3, TSH, osmolality etc.) of cattle were investigated. The experimental animals, crossbreed (Brahman, Afrikander and Hereford) heifers and oxen obtained from Kanhym Estates, Middelburg, were unaccustomed to handling. One group of animals was subjected to the stress of sampling with restraint, a second group was sampled with restraint after transportation and a third group had blood taken after slaughter at the Kanhym abattoir at Balfour. Control blood samples were obtained from Friesland dairy cows accustomed to handling and blood sampling and from crossbreed oxen unaware of the sampling procedure. Both control and experiment groups were studied in the same season. (April and May, 1984). Results were analysed and compared statistically. The blood cortisol, ACTH, lactates and glucose were significantly higher in the experimental groups than in the control group. Cortisol and ACTH values were significantly higher, and the lactate and glucose values significantly lower in the group subjected to the stress of sampling with restraint than in the other two experimental groups. Therefore, if the variables measured are an assessment of stress and change because of stress, then the animals investigated experienced stress. In addition, cattle unaccustomed to handling perceive the slaughtering process as less stressful than blood sampling in a crush (based on cortisol and ACTH results).Item Aspects of the neuroanatomy and physiology of sleep in African mole rats(2012-03-06) Bhagwandin, AdhilMole rats are a unique family of the rodent order and are known for a subterranean lifestyle, reduced eye size, regressed visual system and unusual patterns of circadian rhythmicity (co-existence of rhythmic and arrhythmic chronotypes within a species has been documented). Such dramatic changes especially that of phenotype, may lead to the prediction of significant differences in organisation of the brain and physiology, therefore these unusual phenotypic features form the core rationale providing the impetus for the present series of studies. Neuroanatomical examination of the mole rat brain for immunohistochemical markers of the cholinergic, catecholaminergic, serotonergic, orexinergic, and histaminergic systems revealed neuronal organisation that was remarkably similar to those previously reported in other rodents and mammals, despite the notable differences in lifestyle and phenotype. These results indicate a strong phylogenetic constraint acting at the systems level of neuronal organisation. The study of sleep and wake in rhythmic and arrhythmic chronotypes of a species of mole rat indicated the arrhythmic chronotype spent more time awake with a longer average duration of a waking episode and less time in sleep with a shorter average duration of a SWS episode. While remaining somewhat similar between mole rat chronotypes, total sleep time in the mole rats was significantly reduced in comparison to other rodents. These results also indicate independence of circadian rhythmicity and sleep homeostasis and possible alteration of specific genes involved in the sleep-wake cycle of the mole rats examined. Stereological assessment of absolute numbers of orexinergic neurons revealed that the arrrhythmic chronotype tends to have more orexinergic neurons per gram of body mass that the rhythmic chronotype, leading to the conclusion that enhanced vigilance and peripheral metabolism of the arrhythmic chronotype may underlie this difference. Immunohistochemical identification of nuclei involved with the sleep-wake cycle, showed no difference in the distribution of these nuclei between circadian chronotypes and no major differences when compared to other rodents. Some interesting and potentially functionally important homogeneities were observed in the distribution of GABAergic interneurons within the pontine region. Furthermore differential orexinergic terminal network densities were observed between chronotypes within the arcuate nucleus and the intergeniculate leaflet. Therefore despite unusual features in lifestyle and phenotype, the organisation of the mole rat brain remains remarkably similar to other rodents; however, distinctions of circadian chronotype consistently produced subtle differences in both the anatomy and physiology of these rodents.Item A study of the anatomy and physiology of sleep in the rock hyrax, Procavia capensis(2012-02-28) Gravett, NadineThe rock hyrax, Procavia capensis, is a social diurnal mammal that typically lives in colonies on rocky outcrops and is found throughout most parts of Southern Africa. The aim of this thesis was to describe the sleep phenomenology of the rock hyrax. By means of immunohistochemistry the location and distribution of the cholinergic, catecholaminergic, serotonergic, orexinergic, histaminergic, and the GABAergic systems were described. For the most part these systems and their terminal network distributions followed the general mammalian organisational plan; however, several features, potentially unique to the rock hyrax, were found. These include the presence of cholinergic neurons in the AD and AV nuclei of the dorsal thalamus, parvo- and magnocellular divisions of the cholinergic LDT and PPT nuclei. A dense orexinergic terminal network distribution was noted in the regions coincident with the AD nucleus, a feature only observed in other diurnal mammals. Parvalbumin neurons did not show any association to the sleep related nuclei, whereas calbindin and calretinin neurons were found in all sleep related areas, though with differing densities and some homogeneities. The physiological measurable parameters of sleep were recorded continuously for 72 h under both solitary and social conditions and compared to determine whether differences existed. The results revealed that no major differences existed between the social and solitary conditions, but sleep intensity and REM duration (particularly REM0) was more pronounced in the social condition. REM was ambiguous in these animals, and led to its subdivision into REM1 and REM0. It is possible that REM1 could be a form of low voltage slow wave sleep, but further investigation is required. If REM1 is a form of NonREM sleep it would imply that the rock hyrax has the lowest amount of REM sleep of any terrestrial mammal studied to date.Item Nutrient concentration of inner bark tissue in pine trees in Mpumalanga in relation to baboon damage.(2006-10-27T08:49:37Z) Mcnamara, LorrainePine saw timber plantation forestry on the Eastern Escarpment of South Africa contributes significantly to the economy of the country. Losses to plantation value through fire, insects and disease, and particularly over the last decade, losses due to baboon damage are of serious concern. Anecdotal evidence indicated that baboons damage pine trees shortly following pruning operations and at certain times of the year. A perception existed that damage has increased dramatically, yet no documented evidence to this effect is available. As a result two physiological studies were undertaken to investigate whether changes in nutrient concentration of inner bark tissues of pine trees on the Eastern Escarpment of South Africa, act as triggers for baboon damage. A literature review was also undertaken to document the extent of baboon damage, tree volume and associated economic costs. A comparison was made with Zimbabwe, where baboon damage is quoted to be a severe threat to the continued viability of plantation forestry. The first study investigated changes in nutrient concentration of the soft, inner bark tissue of Pinus patula, in response to pruning measured in five year old plantations in the Mpumalanga Province, South Africa. Samples of tissues were collected from pruned and unpruned trees at 2, 7, 14 and 28 days after 26% of the live crown had been removed in the pruning treatment. Results indicated that live pruning of Pinus patula did not influence nutrient concentration of inner bark tissues at set intervals post pruning. Treatment differences of aggregate data for sample interval showed that potassium concentration increased by 0.03% whereas magnesium concentration decreased by 0.02% following pruning. Aggregate data for treatment showed that phosphorus, carbohydrates (fructose, glucose, sucrose and starch), boron and nitrogen concentration, and moisture content of inner bark tissues varied during the short time period of the study. Variations are attributed to iv the commencement of growth, translocation of nutrients from needles and branches and possibly moisture stress. Results from the study do not support anecdotal evidence that baboon damage to pine plantations which increases shortly after pruning operations is as a direct physiological response to the pruning event. In this study it is much more likely that changes in nutrient concentrations coincided with a remobilization of resources in response to seasonal triggers. In the second study, nutrient concentrations of the inner bark of Pinus patula and Pinus taeda growing on the Eastern Escarpment of South Africa were studied over a seasonal cycle in order to investigate the allegations that baboon damage in the plantations was related to the degree of nutrient remobilization. Significant differences were found in phosphorus concentration and moisture content across seasons and between baboon damaged and undamaged trees. Undamaged Pinus taeda trees recorded the highest phosphorus levels in April 2003 (0.13%). Moisture content was lowest in damaged Pinus patula trees in August 2003 (57%). Anecdotal evidence that baboon damage to pine trees on the Eastern Escarpment of Mpumalanga increases prior to the growing season is supported by the significant changes in inner bark tissue concentration. Nutrient translocation prior to needle fall alters inner bark nutrient concentration, as does moisture stress and demand for nutrients prior to cambial activity. Pine bark is easier to peel during periods of peak cambial activity. These factors are discussed as they may trigger baboon damage. Significantly higher inner bark tissue concentrations of sucrose (4.25 versus 2.61%), starch (4.75 versus 2.84%) and nitrogen (0.61 versus 0.49%) in Pinus taeda compared with Pinus patula, supports anecdotal evidence that Pinus taeda is preferentially damaged by baboons. Baboon damaged trees contained higher concentrations of zinc (30.4 versus 22.3 ppm) and calcium (0.26 versus 0.20%), and lower concentrations of sucrose (2.95 versus 3.91%) and starch (3.21 versus v 4.39%) than undamaged trees, which was attributed to resource allocation to wound response and not that baboons selected trees with higher concentrations of zinc or calcium. The variability of inner bark tissue concentration due to a number of factors highlights that baboon damage in pine plantations is not readily answered, and remains a complex problem. A literature review was undertaken of reported baboon damage occurrence and intensity of damage, following statements that baboon damage to pine plantations is rapidly escalating in the Mpumalanga Province, South Africa. The extent and intensity of baboon damage from the first reported damage (1960’s) until current levels are documented. A comparison is made between Zimbabwe and South Africa where the baboon damage is viewed as a serious problem. The extent of baboon damage in Zimbabwe, expressed as the total percentage of area damaged by baboons as a function of the total area planted to pine for the period 2000-2004 has escalated from 10.8 to 13.3% despite harvesting activities removing damaged trees (Fergusson, 2004). The total area with reported baboon damage in Zimbabwe amounted to 5 317 hectares in 2004 (Fergusson, 2004). In South Africa baboon damage has increased markedly from the first reports of 300 hectares in 1980 (Bigalke, 1980) to 7 641 hectares in 2004. The average percentage of trees damaged in affected compartments is 20.4% with the percentage increasing from 17.2 to 23.6% from 2002-2004. Pinus taeda appears to be the most severely affected species with Pinus elliottii showing increasing levels of damage in many compartments in 2004. Quantifying the value lost by baboon damage to the industry requires reliable assessment methods that are cost effective to implement. Assessment methods need to take into account the position of the damage on the stem, and resultant saw log value that is lost. Assessment methods implemented in South Africa and Zimbabwe are described, and results given by method applied. A standard assessment method is required for comparisons to be made between areas vi with baboon damage. An investigation in Zimbabwe highlighted significant differences between standing tree volume estimations (4.98 – 7.59 m3/ha, with various methods), and actual volume losses (50.45 m3/ha) (Ngorima et. al., 2002). The associated Rand value loss determined by the South African assessment method in 2004 was in excess of 20 million Rand. This estimated loss in revenue does not include losses of incremental growth due to the damage, re-establishment costs, loss of thinning and clearfelling product revenue due to timber wastage, or losses experienced in down line processing at the saw mill. The extent of the baboon damage problem warrants proactive management, continued monitoring and investment into research in order to gain a better understanding of the problem. The increase in the extent of baboon damage from early documented figures is most alarming, showing that the baboon damage problem continues to grow.