Browsing by Author "Bradshaw, D."
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- ItemA statement of intent on the formation of the NCRP on Cardiovascular and Metabolic Disease: A new initiative to fight heart disease, stroke, diabetes and obesity in South Africa(2007) Mayosi, B.; Bryer, A.; Lambert, V.; Levitt, N.; Noakes, T.; Ntsekhe, M.; Opie, L.; Rayner, B.; Zilla, P.; Abrahams, Z.; Abram, M.; Bhagwandin, N.; Bradshaw, D.; Dhansay, A.; Mbewu, A.; Madela-Mntla, N.; Parker, W-A.; Sifunda, S.; Skepu, A.; Steyn, N.; Brown, S.; Mollentze, W.; Brink, P.; Doubell, A.; Hough, S.; Huisamen, B.; Lochner, A.; Moolman-Smook, J.; Reuter, H.; Green-Thompson, W.; Horrocks, J.; Manga, P.; Norris, S.; Norton, G.; Raal, D.; Sliwa, K.; Woodiwiss, A.; Mntla, P.; Motala, A.; Naidoo, D.; Seedat, Y.; Ntutela, S.; Puoane, T.; Schwartz, P.[No abstract available]
- ItemDeveloping a 3D mineral texture quantification method of drill core for geometallurgy(Southern African Institute of Mining and Metallurgy, 2019-04) Voigt, M. J.; Miller, J.; Bbosa, L.; Govender, R. A.; Bradshaw, D.; Mainza, A.; Becker, M.Mineral texture is a critical factor which controls ore variability and is an important attribute in geometallurgy. In relation to downstream processes, it affects the fracture pattern during breakage, where rock strength is inherently a function of mineral texture. Because of the subjective nature of mineral texture, it has not been easy to quantify, especially in the context of a measurement suitable for use in geometallurgical programmes. The aim of this paper is to present the first steps in developing a 3D mineral texture quantification method for drill core and to assess its sensitivity to differences in rock strength using a case study. The methodology includes classifying the textural information using the 3D grey level co-occurrence matrices (GLCM) and X-ray computed tomography (XCT) coupled method. Rock strength tests were performed using the split Hopkinson pressure bar (SHPB). The case study investigates a heterogeneous polymetallic sulphide deposit and a homogeneous shale subdivided into three ’mineral textural types’. The variability is largely captured by the GLCM matrices, and preliminary trends can be observed where the shale is finer grained and has a higher yield strength in comparison with the coarser grained polymetallic sulphide ore.
- ItemEstimating the burden of disease attributable to alcohol use in South Africa in 2000(Health & Medical Publishing Group, 2007) Schneider, M.; Norman, R.; Parry, C.; Bradshaw, D.; Pluddemann, A.Objectives. To make quantitative estimates of the burden of disease attributable to alcohol use by sex and age group in South Africa in 2000. Design. The analysis follows the World Health Organization comparative risk assessment (CRA) methodology. Populationattributable fractions (PAFs) calculated from modelled prevalence estimates and relative risks based on the global review were applied to the burden of disease estimates from the revised South African National Burden of Disease study for 2000. The alcohol-attributable fractions for injuries were directly determined from blood alcohol concentrations (BAC > 0.05 g/ 100 ml) at the time of injury. Monte Carlo simulationmodelling techniques were used to quantify uncertainty in the estimates. Setting. South Africa. Subjects. Adults ≥ 15 years. Outcome measures. Deaths and disability-adjusted life years (DALYs) from ischaemic heart disease, stroke, hypertensive disease, diabetes, certain cancers, liver cirrhosis, epilepsy, alcohol use disorder, depression and intentional and unintentional injuries as well as burden from fetal alcohol syndrome (FAS) and low birth weight. Results. Alcohol harm accounted for an estimated 7.1% (95% uncertainty interval 6.6 - 7.5%) of all deaths and 7.0% (95% uncertainty interval 6.6 - 7.4%) of total DALYs in 2000. Injuries and cardiovascular incidents ranked first and second in terms of attributable deaths. Top rankings for overall attributable burden were interpersonal violence (39.0%), neuropsychiatric conditions (18.4%) and road traffic injuries (14.3%). Interpersonal violence accounted for 42.8% of the injury DALYs attributed to alcohol in males and 25.9% in females. In terms of alcohol-attributable disability, alcohol use disorders ranked first (44.6%), interpersonal violence second (23.2%), and FAS third (18.1%). Conclusions. Particular attention needs to be given to preventing and reducing the burden of alcohol-related homicide and violence, alcohol-related road traffic accidents, alcohol use disorders, and FAS. Multilevel interventions are required to target high-risk drinkers, in addition to creating awareness in the general population of the problems associated with alcohol abuse.
- ItemEvidence insufficient to confirm the value of population screening for diabetes and hypertension in low- and-middle-income settings(Health & Medical Publishing Group, 2015) Durao, S.; Ajumobi, O.; Kredo, T.; Naude, C.; Levitt, N. S.; Steyn, K.; Bradshaw, D.; Young, T.To assess the evidence from systematic reviews on the effect on morbidity and mortality of blanket screening for hypertension or diabetes mellitus compared with targeted, opportunistic or no screening, we searched for relevant systematic reviews and conducted duplicate study selection, data extraction and quality appraisal. Results were summarised narratively. We included two completed reviews of moderate quality and one ongoing Cochrane review. In one completed review, general health checks had no effect on total morbidity or mortality or on healthcare services compared with no health checks. In the other, intensive hypertension screening methods were ineffective in increasing screening uptake or detecting new cases compared with less intensive methods. Both reviews included studies in high-income settings. There is insufficient evidence from currently available systematic reviews to confirm a beneficial effect of blanket screening for hypertension and/or diabetes compared with other types of screening methods in low- and middle-income settings. Scarce resources are being mobilised to implement mass screening intervention for diabetes and hypertension without adequate evidence of its effects. A systematic review is needed to assess clinical effectiveness, cost-effectiveness and overall impact on the health system of screening strategies, especially in low- and middle-income settings such as exist in South Africa. Robust evaluation of these outcomes would then be necessary to inform secondary prevention strategies.
- ItemMasking through averages - intraprovincial heterogeneity in HIV prevalence within the Western Cape(Health & Medical Publishing Group, 2006) Shaikh, N.; Abdullah, F.; Lombard, C. J.; Smit, L.; Bradshaw, D.; Makubalo, L.Objective. To measure HIV prevalence at health-district level in the Western Cape (WC) and to compare these findings with those of the National HIV Antenatal Surveys (NHASs). This investigation aimed to estimate the degree of heterogeneity of HIV prevalence within the province in order to inform the design of appropriate and targeted HIV interventions. Method. Annual cross-sectional, unlinked district HIV antenatal surveys were implemented in all 25 health districts of the WC for the years 2001 - 2004, concurrently with the NHAS. A stratified proportional sample was drawn for each district, involving all 344 antenatal clinics in the province, and the anonymous screening method as described by the World Health Organization (WHO) was applied. Results. The NHAS revealed a significant increase in HIV prevalence in the WC from 8.6% (95% confidence interval (CI): 5.6 - 11.6) in 2001 to 15.4% (95% CI: 12.5 - 18.2) in 2004. The district-level HIV surveys showed wide variation in HIV prevalence across the health districts, which increased progressively during this period (a range of 0.6 - 22% for the year 2001 increased to 1 - 33% in 2004). Spatial analysis of HIV prevalence by health district for this period also revealed progressive spatial growth of the sub-epidemics, with the highest prevalence observed in districts located in the Cape metropole region. Conclusions. These concurrent surveys highlight the fact that examining a provincial estimate of HIV prevalence alone has the potential to mask epicentres within the province. This underscores the importance of expanding the surveillance systems to detect heterogeneity sub-provincially, in order to link with local-level planning and resource allocation.
- ItemMathematical models and the fight against diseases in Africa(Academy of Science for South Africa, 2003) Getz, W. M.; Gouws, E.; Hahne, F.; Kopp, P. E.; Mostert, P.; Muller, C.; Seioghe, C.; Williams, B.; Witten, G.; Bradshaw, D.; Dorrington, R.A new initiative proposes to build capacity across Africa to collect data and conduct quantitative analyses necessary to understand the dynamics of major diseases afflicting the continent, with an initial emphasis on HIV/AIDS.
- ItemPrognostic factors in multiple myeloma(Health and Medical Publishing Group (HMPG), 1986-01) Brink, Stefanie; Bradshaw, D.; Rosenstrauch, W. J. C. J.; Van der Merwe, Aletta M.All patients with multiple myeloma seen over a 9-year period at Tygerberg Hospital were studied retrospectively. Presentation data of 144 patients, as well as individual laboratory results were included in the survival analysis. Cox's proportional hazard model (a non-parametric multivariate regression method) was used to predict survival and divide patients into prognostic groups. The relationship between pairs of variables at the time of diagnosis was investigated. The survival of groups of patients was compared using the generalized Wilcoxon and Savage tests. The association of the following factors with prognosis were again substantiated: haemoglobin; serum creatinine, urea and albumin; percentage of plasma cells in the bone marrow aspirate and trephine biopsy specimen; and the number of lytic lesions on skeletal radiography. The following factors were not substantiated: serum uric acid, light-chain proteinuria, age at presentation of the disease and IgG rather than the IgA class. In addition, a higher serum monoclonal peak size at presentation of the disease, and a more rapid fall in the abnormal serum monoclonal peak within the first 40 days after commencing treatment were associated with a significantly longer survival.
- ItemThe role of hexoprenaline in suprapubic amniocentesis during late pregnancy : a pilot study(Health & Medical Publishing Group, 1984) Cronje, H. S.; Kruger, T. F.; Bradshaw, D.Suprapubic amniocentesis is often complicated by the fetal head being fixed in the pelvis, oligohydramnios or a hyperirritable myometrium. These factors limit the success rate associated with the procedure. If the myometrium is relaxed with a β2-stimulant, a higher success rate may be achieved. This was investigated in a randomized, prospective, double-blind pilot study using hexoprenaline. When four- or five-fifths of the fetal head was palpable above the pelvis, hexoprenaline (17 amniocenteses) showed no advantage over a placebo (16 amniocenteses). However, when three-fifths or less of the fetal head was palpable above the brim, 4 dry taps were obtained in the control group using a placebo (17 amniocenteses), while none occurred in the study group (19 amniocenteses) (P < 0.05). Elevation of the fetal head was less difficult in the study group, but this difference was not statistically significant. These results suggest that hexoprenaline is not indicated for routine use during amniocentesis. When a dry tap is obtained or when marked difficulty is encountered in lifting the fetal head from the pelvis, 10 μg hexoprenaline administered intravenously 5 minutes before amniocentesis appears to facilitate successful completion of the procedure. However, a larger series is necessary to confirm this observation.
- ItemUnnatural deaths, alcohol bans and curfews : evidence from a quasi-natural experiment during COVID-19(Health & Medical Publishing Group, 2021-07) Moultrie, T. A.; Dorrington, R. E.; Laubscher, R.; Groenewald, P.; Parry, C. D. H.; Matzopoulos, R.; Bradshaw, D.Background: Coronavirus disease-19 (COVID-19) restrictions, particularly relating to the sale of alcohol and hours of curfew, have had a marked effect on the temporal pattern of unnatural deaths in South Africa. Methods: Death data were collected over 68 weeks from January 2020 to April 2021, together with information on the nature of restrictions (if any) on the sale of alcohol, and hours of curfew. Data were analysed using a simple ordinary least square (OLS) regression model to estimate the relative contribution of restrictions on the sale of alcohol and hours of curfew to the pattern of excess unnatural deaths. Results: The complete restriction on the sale of alcohol resulted in a statistically significant reduction in unnatural deaths regardless of the length of curfew. To the contrary, periods where no or limited restrictions on alcohol were in force had no significant effect, or resulted in significantly increased unnatural deaths. Conclusions: The present study highlights an association between alcohol availability and the number of unnatural deaths and demonstrates the extent to which those deaths might be averted by disrupting the alcohol supply. While this is not a long-term solution to addressing alcohol-related harm, it further raises the importance of implementing evidence-based alcohol control measures.
- ItemWomen doctors in South Africa : a survey of their experience and opinions(Health & Medical Publishing Group, 1991) Brink, A. J.; Bradshaw, D.; Benade, M. M. M.; Heath, S.The proportion of women entering medical school has increased at some faculties but remains at around 20% at others. A postal survey of 2626 women on the Medical Register of the South African Medical and Dental Council was conducted to investigate aspects related to their work. Fifty-five per cent responded, with a possible bias towards older doctors and graduates from Afrikaans-language faculties. Although a significant majority (86,5%) are in practice, about one-third (33,4%) are employed part-time and nearly one-third (29,4%) reported that they had experienced an interruption of their careers for periods of more than 5 years. Major factors relating to this wastage of medical resources identified by this study were the women's dual responsibility at home and at work, the one-time joint taxation system and discrimination in the workplace, in particular with regard to housing loans. Few women find their way into specialist practice (18,5%), teaching or research, although 68,2% indicated that they would have liked to specialise. Home responsibilities (48,2%) and the structure of the curriculum (31,5%) were the commonly reported difficulties experienced with further study. In addition, the lack of part-time training and the geographical location of such facilities also played a role.