1. Academic Wits Research Publications (Faculties submissions)
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Item The impact of diferences in plasma glucose between glucose oxidase and hexokinase methods on estimated gestational diabetes mellitus prevalence(Nature Research, 2019-05) Dickson, Lynnsay M.; Buchmann, Eckhart J.; Janse Van Rensburg, Charl; Norris, Shane A.We evaluated the extent of measurement discordance between glucose oxidase and hexokinase laboratory methods and the efect of this on estimated gestational diabetes mellitus (GDM) prevalence in a routine clinical setting. 592 consecutive urban African women were screened for GDM. Paired venous specimens were submitted to two independent calibrated laboratories that used either method to measure plasma glucose concentrations. World Health Organisation diagnostic criteria were applied. GDM prevalence determined by the glucose oxidase and hexokinase methods was 6.9% and 5.1% respectively. The overall GDM prevalence was 9%. Only 34% of GDM positive diagnoses were common to both laboratory methods. Bland Altman plots identifed a bias of 0.2mmol/l between laboratory methods. Plasma glucose concentrations measured by the glucose oxidase method were more platykurtic in distribution. Low diagnostic agreement between laboratory methods was further indicated by a Cohen’s kappa of 0.48 (p<0.001). Reports of GDM prevalence using either the glucose oxidase or hexokinase laboratory methods may not be truly interchangeable or directly comparable.Item The burden of cancers associated with HIV in the South African public health sector, 2004–2014: a record linkage study(2019-05) Dhokotera, Tafadzwa; Bohlius, Julia; Spoerr, Adrian; Egger, Matthias; Ncayiyana, Jabulani; Olago, Victor; Singh, Elvira; Sengayi, MazvitaIntroduction: The impact of South Africa’s high human immunodeficiency virus (HIV) burden on cancer risk is not fully understood, particularly in the context of antiretroviral treatment (ART) availability. We examined national cancer trends and excess cancer risk in people living with HIV (PLHIV) compared to those who are HIV-negative. Methods: We used probabilistic record linkage to match cancer records provided by the National Cancer Registry to HIV data provided by the National Health Laboratory Service (NHLS). We also used text search of specific HIV terms from the clinical section of pathology reports to determine HIV status of cancer patients. We used logistic and Joinpoint regression models to evaluate the risk and trends in cancers in PLHIV compared to HIV-negative patients from 2004 to 2014. In sensitivity analysis, we used inverse probability weighting (IPW) to correct for possible selection bias. Results: A total of 329,208 cancer cases from public sector laboratories were reported to the NCR from 2004 to 2014 with the HIV status known for 95,279 (28.9%) cancer cases. About 50% of all the female cancer cases (n = 30,486) with a known status were HIV-positive. PLHIV were at higher risk of AIDS-defining cancers (Kaposi sarcoma [adjusted OR:134, 95% CI:111–162], non-Hodgkin lymphoma [adjusted OR:2.73, 95% CI:2.56–2.91] and, cervix [adjusted OR:1.70, 95% CI:1.63–1.77], conjunctival cancer [adjusted OR:21.5, 95% CI:16.3–28.4] and human papilloma virus (HPV) related cancers (including; penis [adjusted OR:2.35, 95% CI:1.85–2.99], and vulva [adjusted OR:1.94, 95% CI:1.67–2.25]) compared to HIV-negative patients. Analysis using the IPW population yielded comparable results. Conclusion: There is need for improved awareness and screening of conjunctival cancer and HPV-associated cancers at HIV care centres. Further research and discussion is warranted on inclusive HPV vaccination in PLHIV.Item The prevalence of malnutrition and growth percentiles for urban South African children(BMC Public Health, 2019-05) Nyati, Lukhanyo H.; Pettifor, John M.; Norris, Shane A.Background: Low- and middle-income countries (LMIC) are experiencing a double-burden of malnutrition characterised by high prevalence of both under- and over-nutrition. We set out using data from the mixedlongitudinal Birth-to-Twenty Plus (Bt20+) birth cohort, to evaluate the patterns of malnutrition and growth in a large South African (SA) city by; (i) assessing the prevalence of undernutrition from birth to 5 years of age and overweight and obesity from ages 2 to 21 years in black and white, male and female children, and (ii) determining percentiles for height, weight, BMI, waist and hip circumferences and comparing the centiles to American and Dutch references. Methods: Height, weight, waist and hip circumferences were measured on urban black and white SA children from the Bt20+. A total of 3273 children born between April and June 1990 in the Greater Johannesburg Metropolitan area were included in the cohort. Z-scores were derived using the WHO 2006 child growth standards (0–5 years), for defining stunting, underweight and wasting. The International Obesity Task Force (IOTF) references were used to define overweight and obesity. Percentiles were developed using the lambda mu sigma (LMS) method and compared to American and Dutch references. Results: Black children were consistently shorter and black males lighter than white children and American references. The prevalence of stunting peaked at 2 years and was significantly higher in males than females and in black than white children. Black females had a greater prevalence of overweight and obesity than black males from 10 to 17 years. The percentiles for black females for weight and BMI were similar to those of South African white and American references but both black and white South African females had lower waist circumferences than American references. Conclusion: The growth percentiles show that young South African urban black females are experiencing general but not central obesity due to a secular change which is faster in weight than height. High levels of undernutrition persist alongside high levels of over-nutrition with adolescence being a critical period for the upsurge in obesity in females. Early intervention is needed to combat the rise in obesity.Item Performance of the Biomark HD real-time qPCR System (Fluidigm) for the detection of nasopharyngeal bacterial pathogens and Streptococcus pneumoniae typing(Nature Research, 2019-04) Olwagen, Courtney P.; Adrian, Peter V.; Madhi, Shabir A.Traditional qPCR assays for pneumococcal detection and serotype characterization require large sample volume, is expensive and labor intensive. We aimed to develop a quantitative nanofuidic Fluidigm assay to overcome some of these shortcomings. A quantitative Fluidigm assay was established to detect 11 bacterial pathogens, 55 pneumococcal serotypes and 6 serotypes of H. infuenzae. The Fluidigm assay results were compared to conventional qPCR and culture. All reactions in the Fluidigm assay efectively amplifed their respective targets with high sensitivity and specifcity compared to qPCR. There was excellent concordance between qPCR and Fluidigm for detection of carriage prevalence (kappa>0.75) and density (Rho>0.95). Fluidigm identifed an additional 7 (4.2%) serotypes over those detected by qPCR. There was a modest concordance between culture and Fluidigm for the majority of reactions detecting S. pneumoniae serotypes/serogroups (kappa>0.6), with Fluidigm identifying an additional 113 (39.1%) serotypes. Discordant results between the three methods were associated with a low carriage density. The Fluidigm assay was able to detect common pneumococcal serotypes, H. infuenzae serotypes, and other common nasopharyngeal bacterial organisms simultaneously. Deployment of this assay in epidemiological studies could provide better insight into the efect of PCV immunization on the nasopharyngeal microbiota in the communityItem Religiosity and sexual abstinence among Nigerian youths: does parent religion matter?(BioMed Central, 2019-04) Somefun, Oluwaseyi DolapoBackground: Religion plays an important role in youth behaviours, making it a significant factor in the discourse on youth sexuality in sub-Saharan Africa. Several studies have found that religion and religiosity play an important role in the sexual behaviours of young people. However, little research in Nigeria has examined the mechanisms through which religiosity influences youth sexual behaviour and if parents’ religion moderates this relationship. Guided by the social control theory, this paper contributes to the existing literature by examining the relationship between religiosity and youth sexual behaviour. Methods: Data for the study came from 2399 male and female youth aged 16–24 years in four states purposively selected from four regions in Nigeria. Abstinence was the sexual behaviour of interest. Logistic regression was used to examine this relationship. Results: Results showed that 68% of the youth had never had sex. Religiosity was a protective factor for youth sexual behaviour and this positive association was still evident even after controlling for other covariates. Youth who were highly religious (OR – 1.81, CI- 1.13-2.88) had significantly higher odds of abstaining compared to their counterparts who were not religious. Conclusion: Religiosity is a protective factor for sexual abstinence among youth in Nigeria. Policy makers can work around using religious institutions for behavioural change among youth in Nigeria.Item Does education offset the effect of maternal disadvantage on childhood anaemia in Tanzania? Evidence from a nationally representative cross-sectional study(BioMed Central, 2019-04) Ojoniyi, Olaide O.; Odimegwu, Clifford O.; Olamijuwon, Emmanuel O.; Akinyemi, Joshua O.Background: Despite being preventable, anaemia is a major public health problem that affects a sizable number of children under-five years globally and in Tanzania. This study examined the maternal factors associated with the risk of anaemia among under-five children in Tanzania. We also assessed whether higher maternal education could reduce the risks of anaemia among children of women with poor socio-economic status. Methods: Data was drawn from the 2015–16 Tanzania demographic and health survey and malaria indicator survey for 7916 children under five years. Adjusted odds ratios were estimated by fitting a proportional odds model to examine the maternal risk factors of anaemia. Stratified analysis was done to examine how the relationship differed across maternal educational levels. Results: The findings revealed that maternal disadvantage evident in young motherhood [AOR:1.43, 95%CI:1.16–1.75], no formal education [AOR:1.53, 95%CI:1.25–1.89], unemployment [AOR:1.31, 95%CI:1.15–1.49], poorest household wealth [AOR:1.50, 95%CI:1.17–1.91], and non-access to health insurance [AOR:1.26, 95%CI: 1.03–1.53] were risk factors of anaemia among children in the sample. Sub-group analysis by maternal education showed that the risks were not evident when the mother has secondary or higher education. However, having an unmarried mother was associated with about four-times higher risk of anaemia if the mother is uneducated [AOR:4.04, 95%CI:1.98–8.24] compared with if the mother is currently in union.Item Generalized hot attractors(Springer, 2019-03) Goldstein, Kevin; Jejjala, Vishnu; Mashiyane, James Junior; Nampuri SureshNon-extremal black holes are endowed with geometric invariants related to their horizon areas. We extend earlier work on hot attractor black holes to higher dimensions and add a scalar potential. In addition to the event and Cauchy horizons, when we complexify the radial coordinate, non-extremal black holes will generically have other horizons as well. We prove that the product of all of the horizon areas is independent of variations of the asymptotic moduli further generalizing the attractor mechanism for extremal black holes. In the presence of a scalar potential, as typically appears in gauged supergravity, we find that the product of horizon areas is not necessarily the geometric mean of the extremal area, however. We outline the derivation of horizon invariants for stationary backgrounds.Item Prevention care for secondary health conditions among people living with spinal cord injuries: research protocol(Springer Nature, 2019-03) Pilusa, S.; Myezwa, Hellen; Potterton, JoanneObjective: People living with spinal cord injuries are at a high risk to experience preventable secondary health conditions in their lifetime, which can lead to rehospitalisation and death. Given the fact that spinal cord injury is a long term disability requiring on-going care, there is need to strengthen prevention of secondary health conditions. This study aims to establish factors influencing prevention care for secondary health conditions among people living with spinal cord injuries in a metropolitan area in order to develop a prevention model of care. Results: A record review of patients living with spinal cord injuries will be conducted to identify the prevalence of secondary health conditions and associated factors. Semi-structured interviews will be conducted on patients living with spinal cord injuries, their caregivers and therapists to explore the contextual factors (personal and environmental factors) influencing the prevention of secondary health conditions. Thematic analysis will be used to identify the themes. Nominal group technique will be used to develop the prevention model of care for secondary health conditions. This study will be conducted at a tertiary and specialised rehabilitation hospital in South Africa.Item Fat redistribution and accumulation of visceral adipose tissue predicts type 2 diabetes risk in middle-aged black South African women: a 13-year longitudinal study(Springer Nature, 2019-03) Mtintsilana, Asanda; Micklesfield, Lisa K.; Chorell, Elin; Olsson, Tommy; Goedecke, Julia H.Background: Cross-sectional studies in South Africa (SA) have shown that black SA women, despite being more insulin resistant, have less visceral adipose tissue (VAT) and more subcutaneous adipose tissue (SAT) than white women. This study aimed to investigate whether baseline and/or change in body fat and its distribution predict type 2 diabetes (T2D) risk in middle-aged black SA women, 13 years later. Methods: We studied 142 black SA women who are the caregivers of the Birth-to-Twenty plus cohort, and who had normal glucose tolerance (NGT) at baseline. At baseline and follow-up, fasting blood samples, basic anthropometry and dual-energy X-ray absorptiometry-derived body composition were measured. At follow-up, an oral glucose tolerance test was completed. The WHO diabetes diagnostic criteria were used to define NGT, impaired fasting glucose (IFG)/impaired glucose tolerance (IGT), impaired glucose metabolism (IGM) and T2D. Results: At follow-up, 64% of participants remained NGT, whereas 25% developed IGM, and 11% developed T2D. The IGM and the T2D groups were combined for statistical analyses. At baseline, trunk fat mass (FM), VAT but not SAT (measures of central FM) were higher in the IGM/T2D group than the NGT group (p < 0.0001). In contrast, the IGM/T2D group had lower leg %FM at baseline than the NGT group (p < 0.0001). Baseline trunk FM (Odds ratio per 1 kg increase (95% confidence interval, 1.95 (1.43–2.67))), and VAT (OR per 10 cm2 increase, 1.25 (1.10–1.42)), and the change in VAT (1.12 (1.03–1.23)) were associated with greater odds of developing IGM/T2D, whereas baseline leg FM (OR per 1 kg increase, 0.55 (0.41–0.73)) were associated with reduced IGM/T2D risk at follow-up (p < 0.05). Conclusions: Relative fat redistribution, with VAT accumulation, predicted the development of IGM/T2D 13 years before its onset. Prevention of central obesity is a key factor to reduce the risk of developing T2D among middle-aged urban black SA women.Item Characterization of putative DD-carboxypeptidase-encoding genes in Mycobacterium smegmatis(Nature Research, 2019-03) Ealand, Christopher S.; Asmal, Rukaya; Mashigo, Lethabo; Campbell, Lisa; Kana, Bavesh D.Penicillin binding proteins (PBPs) are the target of numerous antimicrobial agents that disrupt bacterial cell wall synthesis. In mycobacteria, cell elongation occurs through insertion of nascent cell wall material in the sub-polar region, a process largely driven by High Molecular Weight PBPs. In contrast, the function of DD-carboxypeptidases (DD-CPases), which are Low Molecular Weight Class 1C PBPs, in mycobacteria remains poorly understood. Mycobacterium smegmatis encodes four putative DD-CPase homologues, which display homology to counterparts in Escherichia coli. Herein, we demonstrate that these are expressed in varying abundance during growth. Deletion of MSMEG_1661, MSMEG_2433 or MSMEG_2432, individually resulted in no defects in growth, cell morphology, drug susceptibility or spatial incorporation of new peptidoglycan. In contrast, deletion of MSMEG_6113 (dacB) was only possible in a merodiploid strain expressing the homologous M. tuberculosis operon encoding Rv3627c (dacB), Rv3626c, Rv3625c (mesJ) and Rv3624c (hpt), suggestive of essentiality. To investigate the role of this operon in mycobacterial growth, we depleted gene expression using anhydrotetracyclineresponsive repressors and noted reduced bipolar peptidoglycan synthesis. These data point to a possible role for this four gene operon, which is highly conserved across all mycobacterial species, in regulating spatial localization of peptidoglycan synthesis.