Martin Kidd

Martin Kidd
Stellenbosch University | SUN · Centre for Statistical Consultation

PhD

About

213
Publications
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Introduction
The Centre for Statistical Consultation, University of Stellenbosch provides a statistical service primarily focussed on students and researchers within the university, but also to researchers outside the university. Visit our website (via the university website) to get more information.

Publications

Publications (213)
Article
There is a lack of comparative data on the occurrence and clinical significance of incidental neuroimaging findings (IFs) in adult research participants with neuropsychiatric disorders and healthy controls. We investigated and compared the frequency, clinical significance and predictors of IFs on structural brain magnetic resonance imaging (MRI) sc...
Preprint
Background: Although multiple sclerosis (MS) is an immune-related disorder, pharmaceutical interventions targeting the immune system do not stop or reverse disability progression; the major challenge for this condition. Studies show that disability progression in MS is associated with vascular comorbidity and brain volume loss, indicating that a mu...
Article
Rapid sensory profiling of a product over time presents a challenge in quality control, particularly when the product has a complex aroma and flavour profile. Polarized sensory positioning (PSP), based on the comparison of samples to fixed references, allows for rapid sensory profiling and data collection across multiple sessions. The efficacy of p...
Article
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Aim: To investigate the role of the chemokines CXCL13, CXCL10 and CXCL8 in the diagnosis of ocular- and neurosyphilis by examining the serum, aqueous humour (AH) and cerebrospinal fluid (CSF) of patients with ocular syphilis. Methods: An observational descriptive study was performed prospectively at Tygerberg Academic Hospital in Cape Town, South...
Article
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Chatbots are increasingly applied in various contexts including helping professions, such as organizational and life coaching. Coaching facilitates individual wellness, behavioral change, and goal attainment in a reflective, non-directive manner, and is considered one of the fastest-growing professions. The use of knowledge imparting service chatbo...
Article
The diagnosis of tuberculous meningitis (TBM) in children is often delayed due to diagnostic difficulties. New tools are urgently needed to improve the diagnosis of the disease in this vulnerable group. The present study aimed to validate the accuracy of recently identified host cerebrospinal (CSF) biomarkers as candidates for the diagnosis of TBM...
Article
Background Behaviors typical of body-focused repetitive behavior disorders such as trichotillomania (TTM) and skin-picking disorder (SPD) are often associated with pleasure or relief, and with little or no physical pain, suggesting aberrant pain perception. Conclusive evidence about pain perception and correlates in these conditions is, however, la...
Article
Exposure to community violence is common in South Africa and negatively impacts on biopsychosocial health. Posttraumatic stress disorder (PTSD) is characterised by symptoms of intrusion, avoidance, hypervigilance and negative alterations in cognition and mood, and can develop consequent to trauma exposure. Individuals who repeatedly experience and...
Article
Background There is an urgent need for new, accurate, rapid, and affordable tuberculosis (TB) diagnostic tests. The aim of the present study was to use mass spectrometry to identify new preliminary candidate TB diagnostic protein biomarkers in saliva obtained from individuals with TB, and patients with other respiratory diseases (ORD). Methods Sal...
Article
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Introduction Many children living with HIV (CLWH) display impaired cognition. Although early combination antiretroviral therapy (ART) produces improved cognitive outcomes, more long-term outcome data are needed. After concluding the Children with HIV Early antiRetroviral (CHER) trial in 2011, we investigated cognitive performance, at seven and nine...
Article
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Background: Trichotillomania (TTM) has been associated with childhood trauma and perceived stress. While it has been hypothesized that hair-pulling regulate negative emotions, the relationship between childhood trauma, perceived stress, emotion regulation, and hair-pulling has not been well-studied. Methods: Fifty-six adults with TTM and 31 healthy...
Article
Objectives 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography- Computed Tomography (PET/CT) scans can be used to assess healing following treatment for spinal tuberculosis (TB) but have limited accessibility and high cost. This study investigated the association between immune biomarkers and FDG-PET/CT activity after ≥9 months of treatment f...
Article
Host markers to monitor the response to tuberculosis (TB) therapy hold some promise. We evaluated the changes in concentration of Mycobacterium tuberculosis (M.tb)-induced soluble biomarkers during early treatment for predicting short- and long-term treatment outcomes. Whole blood samples from 30 cured and 12 relapsed TB patients from diagnosis, we...
Article
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Accurate and affordable point-of-care diagnostics for tuberculosis (TB) are needed. Host serum protein signatures have been derived for use in primary care settings, however validation of these in secondary care settings is lacking. We evaluated serum protein biomarkers discovered in primary care cohorts from Africa reapplied to patients from secon...
Article
Children with Childhood Apraxia of Speech (CAS) often present motor co-ordination difficulties accompanying their speech and sound delays. Therefore, the aim of this study was to investigate the effect of a paired versus a small group gross motor intervention on selected pre-school children, pre-identified with CAS. Children pre-identified with CAS...
Article
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Living with wild mammals is a critical challenge globally, especially in mixed-use landscapes such as Transfrontier Conservation Areas that aim to conserve wildlife as well as implement programs to improve livelihoods. The success of such initiatives depends on local communities willingness to tolerate potential costs from wildlife. However, the dr...
Preprint
Full-text available
Background: The diagnosis of TB remains one of the major challenges in the control of the disease, due to limitations in the currently available diagnostic tests. There is an urgent need for new, accurate, rapid, and affordable diagnostic tests. The aim of the present study was to use mass spectrometry to identify new candidate TB diagnostic protei...
Article
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RationaleObsessive–compulsive disorder (OCD) is characterized by executive function impairment and by clinical responsivity to selective serotonin reuptake inhibitors (SSRIs). Executive planning deficits constitute a candidate endophenotype for OCD. It is not known whether this endophenotype is responsive to acute serotonin manipulation.Objective T...
Article
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Background: Perinatal HIV infection negatively impacts cognitive functioning of children, main domains affected are working memory, processing speed and executive function. Early ART, even when interrupted, improves neurodevelopmental outcomes. Diffusion tension imaging (DTI) is a sensitive tool assessing white matter damage. We hypothesised that...
Article
In recent years, there has been a growing interest in neuropsychological deficits in patients with Cocaine Use Disorder (CUD) and Alcohol Use Disorder (AUD). Besides deficits in working memory (WM), impulsivity and attention, chronic alcohol and cocaine use have neurotoxic effects on frontostriatal areas in the brain. Individuals with deficits in t...
Article
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Background: With the advent of access to antiretroviral treatment (ART), human immunodeficiency virus (HIV) has become a chronic disease and self-management is an important component of its care. Research to date has not explored associations between adolescent HIV self-management and treatment adherence, viral suppression, sexual risk behaviour an...
Article
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Adolescent HIV self-management is a complex phenomenon that has been poorly researched. A mixed-method explorative sequential research design was used to develop an instrument to measure adolescent HIV self-management in the context of the Western Cape, South Africa. The development and validation was undertaken in four phases: (i) individual inter...
Article
Pivot© profile (PP), a method which compares samples to a reference (pivot), has shown profiling potential for complex matrices. However, various aspects require further investigation. This study’s aim was to compare PP to frequency of attribute citation (FC) considering individual judges’ data and sample set complexity. A trained panel analysed th...
Article
Purpose: To identify potential diagnostic biomarkers for herpetic and syphilitic uveitis. Methods: Blood samples were collected from 92 uveitis patients. Concentrations of 47 biomarkers were evaluated in unstimulated Quantiferon supernatants using the Luminex platform. Results: Results showed 11 patients (12%) had herpetic uveitis, 11 (12%) syphili...
Article
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Biomarkers for TB treatment response and outcome are needed. This study characterize changes in immune profiles during TB treatment, define biosignatures associated with treatment outcomes, and explore the feasibility of predictive models for relapse. Seventy-two markers were measured by multiplex cytokine array in serum samples from 78 cured, 12 r...
Article
Successful vertical HIV transmission prevention programmes (VTP) have resulted in an expanding population of HIV-exposed uninfected (HEU) infants whose growth, health and neurodevelopmental outcomes could have consequences for future resource allocation. We compared neurodevelopmental and behavioural outcomes in a prospective cohort of 2–3 year old...
Article
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Background: There is an urgent need for new tools for the diagnosis of TB. We evaluated the usefulness recently described host biomarkers in supernatants from the newest generation of the QuantiFERON test (QuantiFERON Plus) as tools for the diagnosis of active TB. Methods: We recruited individuals presenting at primary health care clinics in Cap...
Article
Background: Obsessive-compulsive disorder (OCD) places individuals at risk for suicidality. Inconsistencies regarding the associated features of suicidality and OCD remain. Methods: Regression analysis determined the extent to which psychiatric comorbidity, illness severity, OCD symptom dimensions, childhood trauma history, and the Val66Met (rs6...
Article
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Habitat degradation and fragmentation have heightened the importance of understanding human tolerance towards wildlife, as the fate of wildlife in multi-use landscapes depends on people's capacity for coexistence. We applied the wildlife tolerance model to examine drivers of tolerance towards Asian elephants Elephas maximus in rural Bangladesh, int...
Article
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Astringency is often difficult to evaluate accurately in wine because of its complexity. This accuracy can improve through training sessions, but it can be time-consuming and expensive. A way to reduce these costs can be the use of wine experts, who are known to be reliable evaluators. Therefore, the aim of this work was to compare the sensory resu...
Article
Abstract Substance Use Disorders (SUD) lead to brain structural and functional deficits associated with cognitive and social functioning in affected individuals and can impact on treatment outcomes. The lack of behavioural autonomy is underpinned by direct reward, high impulsivity and difficulties in planning behaviour. The motor cortex — as part o...
Article
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Introduction: Individuals with Substance Use Disorder (SUD) often have cognitive deficits in multiple domains, including motor timing deficits, with recovery times of up to 1 year. Cognitive deficits influence treatment outcomes and abstinence. To our knowledge, timing deficits have not been investigated with regard to treatment outcome and relapse...
Article
The study was undertaken to gain insight into the nitrogen status of grape juices currently used to make commercial wines in South Africa. This was done as yeast assimilable nitrogen (YAN) is most often suspected as the cause for problematic fermentations and has major implications for the organoleptic qualities of the final product. Using explorat...
Article
Background: The effect of childhood maltreatment (CM) on neuropsychological performance is well established, but the effect of anxiety proneness (AP) on such performance has been underexplored. We assessed the predictive ability of CM and AP, and their interaction, in non-clinical adolescents, for a range of previously documented neuropsychologica...
Article
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Quality plays an important role in the criteria directing wine product development. The evaluation of sensory characteristics associated with wine quality, as perceived by industry professionals, is therefore important. We investigated the suitability of the free-sorting sensory evaluation method, in combination with wine quality scoring using a 20...
Article
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Background: Anxiety disorders in youth are attributable to multiple causal mechanisms, comprising biological vulnerabilities, such as genetics and temperament, and unfavourable environmental influences, such as childhood maltreatment (CM). Objective: A gene-environment (G x E) interaction study was conducted to determine the interactive effect of t...
Data
Figure S1. Flow diagram of participants enrolled and assessments performed at each age per group. Table S1. Correlation between time to first viral suppression (age at first viral load <400 copies/ml) and neurodevelopmental scores at 5 years Table S2. Correlation between baseline CD4 values and neurodevelopmental scores at 5 years Table S3. Comp...
Article
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Introduction Early antiretroviral therapy (ART) has improved neurodevelopmental outcomes of HIV‐infected (HIV‐positive) children; however, little is known about the longer term outcomes in infants commencing early ART or whether temporary ART interruption might have long‐term consequences. In the children with HIV early antiretroviral treatment (CH...
Article
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Results: In patients with high disability scores the mean FA was significantly lower (0.34 ± 0.067) than in the control group (0.45 ± 0.036; p = 0.04), while patients with low disability had mean FA values (0.44 ± 0.014) similar to controls (p = 0.5). Positive associations were found between FA and the iron parameters serum iron, ferritin and perc...
Article
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Background Acute cannabis use stimulates appetite, while general population studies suggest that chronic use is associated with reduced risk of obesity and other cardiometabolic risk factors. Methods In this study, we investigated changes in body mass index (BMI), fasting blood glucose and lipids, and rates of metabolic syndrome risk factors in ca...
Article
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Background: Despite increasing access to antiretroviral therapy in low- and middle-income countries, only 54% of eligible individuals were receiving treatment in Africa by 2015. Recent developments in HIV cure research have been encouraging. However, the complex science and procedures of cure research render the informed consent process challengin...
Article
While acute cannabis use stimulates appetite, general population studies suggest that chronic use is associated with reduced risk of obesity and other cardiometabolic risk factors. In this study we investigated changes in body mass index (BMI), fasting blood glucose and lipids, and rates of metabolic syndrome risk factors in cannabis users vs. non-...
Article
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We investigated host-derived biomarkers that were previously identified in QuantiFERON supernatants, in a large pan-African study. We recruited individuals presenting with symptoms of pulmonary TB at seven peripheral healthcare facilities in six African countries, prior to assessment for TB disease. We then evaluated the concentrations of 12 biomar...
Article
Full-text available
We investigated host-derived biomarkers that were previously identified in QuantiFERON supernatants, in a large pan-African study. We recruited individuals presenting with symptoms of pulmonary TB at seven peripheral healthcare facilities in six African countries, prior to assessment for TB disease. We then evaluated the concentrations of 12 biomar...
Article
Full-text available
The use of non-Saccharomyces yeasts to improve complexity and diversify wine style is increasing, however, the interactions between non-Saccharomyces yeasts and lactic acid bacteria (LAB) have not received much attention. This study investigated the interactions of seven non-Saccharomyces yeast strains of the genera Candida, Hanseniaspora, Lachance...
Article
Purpose: To validate a clinical risk prediction score (Ammann score) to predict adverse events (AEs) in paediatric febrile neutropenia (FN). Patients and methods: Patients <16 years of age were enrolled. A risk prediction score (based on haemoglobin ≥ 9 g/dl, white cell count (WCC) < 0.3 G/l, platelet count <50 G/l and chemotherapy more intensiv...
Article
Mangiferin, a C-glucosyl xanthone, abundant in mango and honeybush, is increasingly targeted for its bioactive properties and thus to enhance functional properties of food. The thermal degradation kinetics of mangiferin at pH 3, 4, 5, 6 and 7 were each modeled at five temperatures ranging between 60 and 140 °C. First-order reaction models were fitt...
Article
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Background: Thought disorder and visual-perceptual deficits have been well documented, but their relationships with clinical symptoms and cognitive function remain unclear. Cognitive-perceptual deficits may underscore clinical symptoms in schizophrenia patients. Aim: This study aimed to explore how thought disorder and form perception are related...
Article
Increased share repurchase activity has raised renewed concerns as to whether the positive share price effect generally associated with share repurchase announcements is motivating companies to repurchase shares rather than to invest in future growth. This study focused on ascertaining the significant determinants of the choice between share repurc...
Article
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A bidirectional communication between the immune and endocrine systems exists and facilitates optimum responses in the host during infections. This is in part achieved through changes in secretion patterns of hypothalamic hormones induced by inflammatory cytokines. The aim of this study was to elucidate the immune–endocrine alterations during tuber...
Article
Objectives: Post-traumatic stress disorder is characterized by impaired fear extinction and excessive anxiety. D-Cycloserine (DCS) has previously been shown to facilitate fear extinction and decrease anxiety in animal and human studies. This study utilized a contextual fear-conditioning animal model to investigate the involvement of microRNAs (miR...
Article
Honeybush herbal tea is produced from the endemic South African Cyclopia species. Plant material subjected to a high-temperature oxidation step (“fermentation”) forms the bulk of production. Production lags behind demand forcing tea merchants to use blends of available material to supply local and international markets. The distinct differences in...
Article
Thermal stability of the benzophenones, 3-β-D-glucopyranosyl-4-β-D-glucopyranosyloxyiriflophenone (1), 3-β-D-glucopyranosylmaclurin (2) and 3-β-D-glucopyranosyliriflophenone (3), and the xanthones, mangiferin (4) and isomangiferin (5), was assessed separately in an aqueous model solution (pH 5) to delineate their major degradation products and mech...
Article
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Immunoglobulin G (IgG) based tests for the diagnosis of active tuberculosis (TB) disease often show a lack of specificity in TB endemic regions, which is mainly due to a high background prevalence of LTBI. Here, we investigated the combined performance of the responses of different Ig classes to selected mycobacterial antigens in primary healthcare...
Article
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Background IgG-based tests for the diagnosis of active tuberculosis disease (TB) often show a lack of specificity in TB endemic regions, which is mainly due to a high background prevalence of latent TB infection (LTBI). Here, we investigate the combined performance of the responses of different Ig classes to selected mycobacterial antigens in prima...
Article
Background: Neurological soft signs (NSS) are proposed to represent both state- and trait-related features of schizophrenia. Method: We assessed the course of NSS with the Neurological Evaluation Scale (NES) over 12months of standardised treatment in 126 patients with first-episode schizophrenia, schizophreniform or schizoaffective disorder, and...
Article
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Childhood trauma is a recognised risk factor for schizophrenia. It has been proposed that childhood trauma interferes with normal neurodevelopment, thereby establishing a biological vulnerability to schizophrenia. Poor premorbid adjustment is frequently a precursor to schizophrenia, and may be a manifestation of neurodevelopmental compromise. We in...
Conference Paper
Full-text available
The general assumption is that red wine’s astringency perception is directly related to the phenolic composition, especially tannins. Normally when this relationship is studied, a trained panel is used, but this can be an expensive option. However, it is not clear whether winemakers can be used for this type of studies. Therefore, the main aim of...
Article
Full-text available
Background and purpose: Fractional anisotropy in the frontal white matter, corpus callosum, and internal capsule is abnormal in human immunodeficiency virus-positive (HIV+) adults. We describe the distribution and nature of white matter abnormalities in a cohort of children who started antiretroviral therapy within the first year of life and the b...
Article
Human-wildlife conflict (HWC) is a complex conservation issue and acknowledging the human dimensions of the problem is critical. Here we propose the Wildlife Tolerance Model (WTM), a novel theoretical framework to identify key drivers of tolerance to living with damage-causing wildlife. The WTM proposes an outer model, where the extent to which a p...
Article
Full-text available
Objective In low-resource settings, childhood mortality secondary to delays in triage and treatment remains high. This paper seeks to evaluate the impact of the novel Sick Children Require Emergency Evaluation Now (SCREEN) tool on the waiting times of critically ill children who present for care to primary healthcare clinics in Cape Town, South Afr...
Article
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Contradictory findings have been reported from Africa with regard to the risk of developing Burkitt's lymphoma (BL) in sickle cell trait (AS)carriers. Haemoglobin electrophoresis was performed in 78 BL patients in the Northwest region of Cameroon, and in 78 nearest-neighbourcontrols of the same age, sex and tribe from the same village. AS was confi...