The prognostic signifi cance of normal technetium-99m MIBI myocardial perfusion spect imaging over a four-year follow-up period

normal Tc-99m MIBI myocardial perfusion study has previously been shown to indicate a benign prognosis. Our aim was to determine the longer term prognosis of a normal study in our patient population. Methods: A retrospective evaluation of 209 patients with a normal Tc-99m MIBI study was performed. Follow-up data was obtained in 157 patients, with complete follow-up in 121 (mean follow-up period of 56 months). In 36 patients only partial follow-up was possible (32 months follow-up). No follow-up data, except for the possible registration of deaths, could be obtained in 52. Patients were evaluated for the occurrence of primary or secondary cardiac events. Results: The study group had a moderate pre-test probability for coronary artery disease (48 + 30.7%). Two possible cardiac deaths occurred (cardiac death rate of 0.95%). No primary events occurred in the group with complete follow-up, but 6 secondary events were recorded (cardiac event rate of 4.9%). No primary or secondary events occurred in the partial follow-up group during the follow-up period. The incidence of secondary or non-fatal primary events in this group for the period after they were lost to follow-up or in the group with no follow-up could not be ascertained. There was, however, no statistically significant difference between these groups regarding age, pre-test probability and exercise parameters. Conclusion: Similar to the findings with Tl-201, our study indicates a favourable longer term prognosis after a normal Tc-99m MIBI study

Isovaleric acidaemia in two South African children

CITATION: Malan, C., Neethling, A. C. & Shanley, B. C. 1977. Isovaleric acidaemia in two South African children. South African Medical Journal, 51(26):980-983.The original publication is available at http://www.samj.org.zaTwo siblings who were repeatedly admitted to hospital with acute episodes of vomiting, dehydration and coma were found to be suffering from isovaleric acidaemia. This condition is a rare inherited abnormality of leucine metabolism, which is frequently fatal in the early weeks of life and leads to mental retardation in a high proportion of those who survive early attacks. However, both out patients were of normal intelligence. The clinical presentation, biochemical defect, diagnosis and suggested therapies are reviewed.Publisher’s versio

Characterisation, modification and mathematical modelling of sudsing

A programme of research is outlined which considers the foaming performance and foam behaviour of surfactant systems commonly encountered in hand-wash laundry detergent applications. An experimental study of the physical chemistry of foam generation indicates that precipitation of a typical anionic surfactant with calcium forms mesophase particles and causes a marked reduction in the rate of transport of surfactant to air–water surfaces and a concomitant reduction in foaming. Oily soil antifoam effects are however insensitive to the presence of calcium, being equally effective regardless of pH and calcium content. They may be reproduced by a simple particle–oil mixture of a saturated and an unsaturated triglyceride (e.g. tristearin and triolein respectively). A detailed foam rheometry study is performed using foam flowing through a constriction. Bubble shapes are used to deduce the normal and shear stresses across the foam flow field. Broad agreement between the experimental stress field and that obtained from quasistatic simulations is demonstrated. As foam flow-rate increases, a different model, which takes explicit account of viscous dissipative forces within the foam flow field is required. The dissipative foam flow model predicts differential shrinkage and stretch rates of foam films. Coupled to a model for surfactant transport, this shows the extent to which surfactant concentration accumulates in shrinking films and is depleted in stretching films. In addition to film stretching, it is also important to know about film bursting or failure rates. Here failure rates are estimated using capillary suction pressures exerted on the films by Plateau border channels around film edges. The failure rates can then be employed to predict the evolution of bubble size at various spatial locations in a foam: reasonable agreement with experimental bubble size distributions is obtained

Numerical simulation of scour below pipelines using flexible mesh methods

Evaluating bed morphological structure and evolution (specifically the scoured bed level) accurately using numerical models is critical for analyses of the stability of many marine structures. This paper discusses the performance of an implementation within Fluidity, an open source, general purpose, computational fluid dynamics (CFD) code, capable of handling arbitrary multi-scale unstructured tetrahedral meshes and including algorithms to perform dynamic anisotropic mesh adaptivity. The flexibility over mesh structure and resolution that these capabilities provide makes it potentially highly suitable for coupling the structural scale with larger scale ocean dynamics. In this very preliminary study the solver approach is demonstrated for an idealised scenario. Discontinuous Galerkin finite-element (DG-FEM) based discretisation methods have been used for the hydrodynamics and morphological calculations, and automatic mesh deformation has been utilised to account for bed evolution changes while preserving the validity and quality of the mesh. In future work, the solver will be used in three-dimensional impinging jet and other industrial and environmental scour studies

Students’ entrepreneurial learning through an internship abroad: A cross-cultural experience

Background: Cross-cultural learning provides students with the opportunity for improved self-awareness when they are placed in unfamiliar situations where their understanding of who they are and what they can do is challenged or expanded. This paper built on the concepts of experiential learning in rich contexts and self-image shocks and explored the research question on how cross-cultural learning in entrepreneurship exchange programmes offered students unique personal learning possibilities and outcomes. Aim: The aim was to build new theoretical and empirical knowledge on the influence and importance of cross-cultural learning in entrepreneurship education (EE). Setting: The study involved South African (SA) students taking part in an internship programme in the vibrant entrepreneurial ecosystem of Bergen, Norway. Methods: Adopting a longitudinal design and purposive sampling, four SA students were included in the study. Data were acquired from two reflective group sessions, on two separate instances, and a final student reflection report. The interviews were transcribed and coded along with the written reflection reports and these data sources were subjected to thematic analysis. Results: Four themes were uncovered: Learning about the entrepreneurial culture triggers comparison with own culture, Embracing uncertainty and developing entrepreneurial capabilities, Transformational learning through self-image shocks, Can I become a future entrepreneur? Where am I going? Conclusion: The research highlighted the importance of cross-cultural experience and foreignness as powerful triggers in stimulating students’ introspection and development of self-image. Contribution: The research combines two research streams, hence advancing our theoretical conceptualisation of cross-cultural learning in EE

Estimating the changing disease burden attributable to raised low-density lipoprotein cholesterol in South Africa for 2000, 2006 and 2012

Background. Low-density lipoprotein cholesterol (LDL-C) is the most important contributor to atherosclerosis, a causal factor for ischaemic heart disease (IHD) and ischaemic stroke. Although raised LDL-C is a key contributor to cardiovascular disease (CVD), the exact attributable disease risk in South Africa (SA) is unknown. The the first SA comparative risk assessment (SACRA1) study assessed the attributable burden of raised total cholesterol, and not specifically LDL-C. Objectives. To estimate the national mean serum LDL-C by age, year and sex and to quantify the burden of disease attributable to LDL-C in SA for 2000, 2006 and 2012. Methods. The comparative risk assessment (CRA) method was used. Estimates of the national mean of LDL-C, representing the 3 different years, were derived from 14 small observational studies using a meta-regression model. A theoretical minimum risk exposure level (TMREL) of 0.7 - 1.3 mmol/L was used. LDL-C estimates together with the relative risks from the Global Burden of Disease Study 2017 were used to calculate a potential impact fraction (PIF). This was applied to IHD and ischaemic stroke estimates sourced from the Second National Burden of Disease Study. Attributable deaths, years of life lost, years lived with disability and disability-adjusted life years (DALYs) were calculated. Uncertainty analysis was performed using Monte Carlo simulation. Results. LDL-C declined from 2.74 mmol/L in 2000 to 2.58 mmol/L in 2012 for males, while in females it declined from 3.05 mmol/L in 2000 to 2.91 mmol/L in 2012. The PIFs for LDL-C showed a slight decline over time, owing to the slight decrease in LDL-C levels. Attributable DALYs increased between 2000 (n=286 712) and 2006 (n=315 125), but decreased thereafter in 2012 (n=270 829). Attributable age-standardised death rates declined between 2000 and 2012 in both sexes: in males from 98 per 100 000 members of the population in 2000 to 78 per 100 000 in 2012, and in females from 81 per 100 000 in 2000 to 58 per 100 000 in 2012. Conclusions. Mean LDL-C levels were close to 3 mmol/L, which is the recommended level at which cholesterol-lowering treatment should be initiated for people at low and moderate risk for cardiovascular outcomes. The decreasing trend in the age-standardised attributable burden due to LDL-C is encouraging, but it can be lowered further with the introduction of additional population-based CVD prevention strategies. This study highlights the fact that high LDL-C concentration in relation to the TMREL in SA is responsible for a large proportion of the emerging CVD, and should be targeted by health planners to reduce disease burden

Estimating the changing burden of disease attributable to unsafe water and lack of sanitation and hygiene in South Africa for 2000, 2006 and 2012

Background. The incidence of diarrhoeal disease is closely linked to socioeconomic and environmental factors, household practices and access to health services. South African (SA) district health information and national survey data report wide variation in the incidence and prevalence of diarrhoeal episodes in children under 5 years of age. These differentials indicate potential for reducing the disease burden through improvements in provision of water and sanitation services and changes in hygiene behaviour. Objectives. To estimate the burden of disease attributed to unsafe water, sanitation and hygiene (WASH) by province, sex and age group for SA in 2000, 2006 and 2012. Methods. Comparative risk assessment methodology was used to estimate the disease burden attributable to an exposure by comparing the observed risk factor distribution with a theoretical lowest possible population distribution. The study adapts the original World Health Organization scenario-based approach for estimating diarrhoeal disease burden from unsafe WASH, by assigning different standards of household water and sanitation-specific geographical classification to capture SA living conditions in rural, urban and informal settlements. Results. SA experienced an improvement in water and sanitation supply in eight of the nine provinces between 2001 and 2011, with the exception of Northern Cape Province. In 2011, 41% of South Africans lived with poor water and sanitation conditions; however, wide provincial inequalities exist. In 2012, it was estimated that 84.1% of all deaths due to diarrhoeal disease were attributable to unsafe WASH; this equates to 13 757 deaths (95% uncertainty interval (UI) 13 015 - 14 300). Of these diarrhoeal disease deaths, 48.2% occurred in children under 5 years of age, accounting for 13.9% of all deaths in this age group (95% UI 13.1 - 14.4). Between 2000 and 2012, the proportion of deaths attributable to diarrhoea reduced from 3.6% to 2.6%. Gauteng and Western Cape provinces experienced much lower WASHattributable death rates than the more rural, poorer provinces. Conclusion. Unsafe WASH remains an important risk factor for disease in SA, especially in children. High priority needs to be given to the provision of safe and sustainable sanitation and water facilities and promoting safe hygiene behaviours. The COVID-19 pandemic has reinforced the critical importance of clean water for preventing and containing disease

Estimating the changing burden of disease attributable to childhood stunting, wasting and underweight in South Africa for 2000, 2006 and 2012

Background. National estimates of childhood undernutrition display uncertainty; however, it is known that stunting is the most prevalent deficiency. Child undernutrition is manifest in poor communities but is a modifiable risk factor. The intention of the study was to quantify trends in the indicators of child undernutrition to aid policymakers. Objectives. To estimate the burden of diseases attributable to stunting, wasting and underweight and their aggregate effects in South African (SA) children under the age of 5 years during 2000, 2006 and 2012. Methods. The study applied comparative risk assessment methodology. Data sources for estimates of prevalence and population distribution of exposure in children under 5 years were the National Food Consumption surveys and the SA National Health and Nutrition Examination Survey conducted close to the target year of burden. Childhood undernutrition was estimated for stunting, wasting and underweight and their combined ‘aggregate effect’ using the World Health Organization (WHO) 2006 standard. Population-attributable fractions for the disease outcomes of diarrhoea, lower respiratory tract infections, measles and protein-energy malnutrition were applied to SA burden of disease estimates of deaths, years of life lost, years lived with a disability and disability-adjusted life years for 2000, 2006 and 2012. Results. Among children aged under 5 years between 1999 and 2012, the distribution of anthropometric measurements <‒2 standard deviations from the WHO median showed little change for stunting (28.4% v. 26.6%), wasting (2.6% v. 2.8%) and underweight (7.6% v. 6.1%). In the same age group in 2012, attributable deaths due to wasting and aggregated burden accounted for 21.4% and 33.2% of the total deaths, respectively. Attributable death rates due to wasting and aggregate effects decreased from ~310 per 100 000 in 2006 to 185 per 100 000 in 2012. Conclusion. The study shows that reduction of childhood undernutrition would have a substantial impact on child mortality. We need to understand why we are not penetrating the factors related to nutrition of children that will lead to reducing levels of stunting

Estimating the burden of disease attributable to household air pollution from cooking with solid fuels in South Africa for 2000, 2006 and 2012

Background. Household air pollution (HAP) due to the use of solid fuels for cooking is a global problem with significant impacts on human health, especially in low- and middle-income countries. HAP remains problematic in South Africa (SA). While electrification rates have improved over the past two decades, many people still use solid fuels for cooking owing to energy poverty. Objectives. To estimate the disease burden attributable to HAP for cooking in SA over three time points: 2000, 2006 and 2012. Methods. Comparative risk assessment methodology was used. The proportion of South Africans exposed to HAP was assessed and assigned the estimated concentration of particulate matter with a diameter <2.5 μg/m3 (PM2.5) associated with HAP exposure. Health outcomes and relative risks associated with HAP exposure were identified. Population-attributable fractions and the attributable burden of disease due to HAP exposure (deaths, years of life lost, years lived with disability and disability-adjusted life years (DALYs)) for SA were calculated. Attributable burden was estimated for 2000, 2006 and 2012. For the year 2012, we estimated the attributable burden at provincial level. Results. An estimated 17.6% of the SA population was exposed to HAP in 2012. In 2012, HAP exposure was estimated to have caused 8 862 deaths (95% uncertainty interval (UI) 8 413 - 9 251) and 1.7% (95% UI 1.6% - 1.8%) of all deaths in SA, respectively. Loss of healthy life years comprised 208 816 DALYs (95% UI 195 648 - 221 007) and 1.0% of all DALYs (95% UI 0.95% - 1.0%) in 2012, respectively. Lower respiratory infections and cardiovascular disease contributed to the largest proportion of deaths and DALYs. HAP exposure due to cooking varied across provinces, and was highest in Limpopo (50.0%), Mpumalanga (27.4%) and KwaZulu-Natal (26.4%) provinces in 2012. Age standardised burden measures showed that these three provinces had the highest rates of death and DALY burden attributable to HAP. Conclusion. The burden of disease from HAP due to cooking in SA is of significant concern. Effective interventions supported by legislation and policy, together with awareness campaigns, are needed to ensure access to clean household fuels and improved cook stoves. Continued and enhanced efforts in this regard are required to ensure the burden of disease from HAP is curbed in SA

Estimating the changing disease burden attributable to high body mass index for South Africa for 2000, 2006 and 2012

Background. A high body mass index (BMI) is associated with several cardiovascular diseases, diabetes and chronic kidney disease, cancers, and other selected health conditions. Objectives. To quantify the deaths and disability-adjusted life years (DALYs) attributed to high BMI in persons aged ≥20 years in South Africa (SA) for 2000, 2006 and 2012. Methods. The comparative risk assessment (CRA) methodology was followed. Meta-regressions of the BMI mean and standard deviation from nine national surveys spanning 1998 - 2017 were conducted to provide estimates by age and sex for adults aged ≥20 years. Population attributable fractions were calculated for selected health outcomes using relative risks identified by the Global Burden of Disease Study (2017), and applied to deaths and DALY estimates from the second South African National Burden of Disease Study to estimate the burden attributed to high BMI in a customised Microsoft Excel workbook. Monte Carlo simulation-modelling techniques were used for the uncertainty analysis. BMI was assumed to follow a log-normal distribution, and the theoretical minimum value of BMI below which no risk was estimated was assumed to follow a uniform distribution from 20 kg/m2 to 25 kg/m2. Results. Between 2000 and 2012, mean BMI increased by 6% from 27.7 kg/m2 (95% confidence interval (CI) 27.6 - 27.9) to 29.4 kg/m2 (95% CI 29.3 - 29.5) for females, and by 3% from 23.9 kg/m2 (95% CI 23.7 - 24.1) to 24.6 kg/m2 (95% CI 24.5 - 24.8) for males. In 2012, high BMI caused 58 757 deaths (95% uncertainty interval (UI) 46 740 - 67 590) or 11.1% (95% UI 8.8 - 12.8) of all deaths, and 1.42 million DALYs (95% UI 1.15 - 1.61) or 6.9% (95% UI 5.6 - 7.8) of all DALYs. Over the study period, the burden in females was ~1.5 - 1.8 times higher than that in males. Type 2 diabetes mellitus became the leading cause of death attributable to high BMI in 2012 (n=12 382 deaths), followed by hypertensive heart disease (n=12 146), haemorrhagic stroke (n=9 141), ischaemic heart disease (n=7 499) and ischaemic stroke (n=4 044). The age-standardised attributable DALY rate per 100 000 population for males increased by 6.6% from 3 777 (95% UI 2 639 - 4 869) in 2000 to 4 026 (95% UI 2 831 - 5 115) in 2012, while it increased by 7.8% for females from 6 042 (95% UI 5 064 - 6 702) to 6 513 (95% UI 5 597 - 7 033). Conclusion. Average BMI increased between 2000 and 2012 and accounted for a growing proportion of total deaths and DALYs. There is a need to develop, implement and evaluate comprehensive interventions to achieve lasting change in the determinants and impact of overweight and obesity, particularly among women