Browsing by Author "Kidd, Martin"
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- ItemAfrica-wide evaluation of host biomarkers in QuantiFERON supernatants for the diagnosis of pulmonary tuberculosis(Nature Research, 2018-02-08) Chegou, Novel N.; Sutherland, Jayne S.; Namuganga, Anna-Ritah; Corstjens, Paul L. A. M.; Geluk, Annemieke; Gebremichael, Gebremedhin; Mendy, Joseph; Malherbe, Stephanus; Stanley, Kim; Van Der Spuy, Gian D.; Kriel, Magdalena; Loxton, Andre G.; Kriel, Belinda; Simukonda, Felanji; Bekele, Yonas; Sheehama, Jacob A.; Nelongo, Josefina; Van Der Vyver, Marieta; Gebrexabher, Atsbeha; Hailu, Habteyes; Esterhuyse, Maria M.; Rosenkrands, Ida; Aagard, Claus; Kidd, Martin; Kassa, Desta; Mihret, Adane; Howe, Rawleigh; Cliff, Jacqueline M.; Crampin, Amelia C.; Mayanja-Kizza, Harriet; Kaufmann, Stefan H. E.; Dockrell, Hazel M.; Ottenhoff, Tom H. M.; Walzl, Gerhard; AE-TBC consortiumWe 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 biomarkers in stored QuantiFERON supernatants using the Luminex platform. Based on laboratory, clinical and radiological findings and a pre-established algorithm, participants were classified as TB disease or other respiratory diseases(ORD). Of the 514 individuals included in the study, 179(34.8%) had TB disease, 274(51.5%) had ORD and 61(11.5%) had an uncertain diagnosis. A biosignature comprising unstimulated IFN-γ, MIP-1β, TGF-α and antigen-specific levels of TGF-α and VEGF, identified on a training sample set (n = 311), validated by diagnosing TB disease in the test set (n = 134) with an AUC of 0.81(95% CI, 0.76–0.86), corresponding to a sensitivity of 64.2%(95% CI, 49.7–76.5%) and specificity of 82.7%(95% CI, 72.4–89.9%). Host biomarkers detected in QuantiFERON supernatants can contribute to the diagnosis of active TB disease amongst people presenting with symptoms requiring investigation for TB disease, regardless of HIV status or ethnicity in Africa.
- ItemAnxiety sensitivity in school attending youth : exploratory and confirmatory factor analysis of the 18-item CASI in a multicultural South African sample(Frontiers, 2016-01-07) Martin, Lindi; Kidd, Martin; Seedat, SorayaENGLISH SUMMARY : Anxiety sensitivity (AS) is a risk factor for the development of anxiety disorders in youth. To date, the applicability of the Childhood Anxiety Sensitivity Index (CASI) in youth from a low or middle income country (LMIC) setting on the African continent has not been assessed. A representative sample of 1149 secondary school learners from 29 schools in Cape Town, South Africa, participated in the study. Participants completed the CASI on a single occasion. One-, two-, and four-factor models of the CASI were assessed. A one-factor solution that comprised items predominantly represented by physical concerns appeared to provide the best fit to our data, however, relatively low variance (26%) was explained. Subsequent item deletion resulted in a 9-item ‘physical concerns’ factor that showed good construct reliability (0.83) but also explained a low amount of variance (35%). In terms of gender, a one-factor model provided the best fit, however, low variance was explained (i.e., 25%). Configural, metric and scalar invariance of the CASI by gender was determined. Our results suggest that the 18-item CASI is not applicable to our target population and may require adaptation in this population; however, replication of this study in other multicultural adolescent samples in South Africa is first needed to further assess the validity of the AS construct as measured by the CASI.
- ItemBasic in-mouth attribute evaluation : a comparison of two panels(MDPI, 2018-12-21) Mihnea, Mihaela; Aleixandre-Tudo, Jose Luis; Kidd, Martin; Du Toit, WesselAstringency 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 results and the panel performance obtained using trained panelists versus wine experts (winemakers). Judges evaluated twelve red wines for in-mouth basic perception (sweet, sour, bitter, astringent, and burning sensation) following the same tasting protocol and with the samples being presented in two different tasting modalities. Panels’ performance and relationship between the chemical composition and the sensory perception were investigated. Both panels showed similar consistency and repeatability, and they were able to accurately measure the astringency of the wines. However, the significant correlations between sensory scores and chemical composition varied with the panel and the tasting modality. From our results, we could see that winemakers tended to discriminate better between the samples when the differences were very small.
- ItemCognitive-perceptual deficits and symptom correlates in first-episode schizophrenia(AOSIS Publishing, 2017) Olivier, Riaan M.; Kilian, Sanja; Chiliza, Bonginkosi; Asmal, Laila; Oosthuizen, Petrus P.; Emsley, Robin A.; Kidd, MartinBackground: 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 with clinical symptoms and cognitive dysfunction in first-episode schizophrenia. Setting: Forty-two patients with a first-episode of schizophrenia, schizophreniform or schizoaffective disorder were recruited from community clinics and state hospitals in the Cape Town area. Methods: Patients were assessed at baseline with the Rorschach Perceptual Thinking Index (PTI), the Positive and Negative Syndrome Scale (PANSS) and the MATRICS Cognitive Consensus Battery (MCCB). Spearman correlational analyses were conducted to investigate relationships between PTI scores, PANSS factor analysis-derived domain scores and MCCB composite and subscale scores. Multiple regression models explored these relationships further. Results: Unexpectedly, poor form perception (X- %) was inversely correlated with the severity of PANSS positive symptoms (r = -0.42, p = 0.02). Good form perception (XA%) correlated significantly with speed of processing (r = 0.59, p < 0.01), working memory (r = 0.48, p < 0.01) and visual learning (r = 0.55, p < 0.01). PTI measures of thought disorder did not correlate significantly with PANSS symptom scores or cognitive performance. Conclusions: Form perception is associated with positive symptoms and impairment in executive function during acute psychosis. These findings suggest that there may be clinical value in including sensory-perceptual processing tasks in cognitive remediation and social cognitive training programmes for schizophrenia patients.
- ItemCombination of gene expression patterns in whole blood discriminate between tuberculosis infection states(BioMed Central, 2014-05) Mihret, Adane; Loxton, Andre G.; Bekele, Yonas; Kaufmann, Stefan H. E.; Kidd, Martin; Haks, Marielle C.; Ottenhoff, Tom H. M.; Aseffa, Abraham; Howe, Rawleigh; Walzl, GerhardBackground Genetic factors are involved in susceptibility or protection to tuberculosis (TB). Apart from gene polymorphisms and mutations, changes in levels of gene expression, induced by non-genetic factors, may also determine whether individuals progress to active TB. Methods We analysed the expression level of 45 genes in a total of 47 individuals (23 healthy household contacts and 24 new smear-positive pulmonary TB patients) in Addis Ababa using a dual colour multiplex ligation-dependent probe amplification (dcRT-MLPA) technique to assess gene expression profiles that may be used to distinguish TB cases and their contacts and also latently infected (LTBI) and uninfected household contacts. Results The gene expression level of BLR1, Bcl2, IL4d2, IL7R, FCGR1A, MARCO, MMP9, CCL19, and LTF had significant discriminatory power between sputum smear-positive TB cases and household contacts, with AUCs of 0.84, 0.81, 0.79, 0.79, 0.78, 0.76, 0.75, 0.75 and 0.68 respectively. The combination of Bcl2, BLR1, FCGR1A, IL4d2 and MARCO identified 91.66% of active TB cases and 95.65% of household contacts without active TB. The expression of CCL19, TGFB1, and Foxp3 showed significant difference between LTBI and uninfected contacts, with AUCs of 0.85, 0.82, and 0.75, respectively, whereas the combination of BPI, CCL19, FoxP3, FPR1 and TGFB1 identified 90.9% of QFT- and 91.6% of QFT+ household contacts. Conclusions Expression of single and especially combinations of host genes can accurately differentiate between active TB cases and healthy individuals as well as between LTBI and uninfected contacts.
- ItemCosts of coexistence : understanding the drivers of tolerance towards Asian elephants Elephas maximus in rural Bangladesh(Fauna & Flora International, 2020) Saif, Omar; Kansky, Ruth; Palash, Anwar; Kidd, Martin; Knight, Andrew T.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, interviewing local people in 17 villages. We used structural equation modelling to identify causal pathways in which elephant-related exposure, positive and negative interactions, costs and benefits (tangible and intangible) contributed to tolerance. Contrary to expectations, monetary costs were non-significant in shaping tolerance despite major impacts on livelihoods. Instead, intangible costs and intangible benefits were significant factors determining tolerance. Furthermore, reducing people's exposure to elephants would not necessarily affect tolerance, nor would increasing positive interactions. We discuss how the socio-economic and bio-cultural dynamics of local communities can explain these results, and demonstrate how our model can be used to incorporate such complexities into conservation decision-making. For instance, compensation schemes aim to recompense monetary losses and direct damages, to improve tolerance, whereas our results suggest a more effective approach would be to enhance resilience to non-monetary costs and improve perceived benefits. We conclude that future studies should pay increased attention to intangible costs and consider the less direct drivers of tolerance. Through repeated testing of universal models such as that presented here, broad trends may emerge that will facilitate the application of policies across contexts and landscapes.
- ItemDetection of a combination of serum IgG and IgA antibodies against selected mycobacterial targets provides promising diagnostic signatures for active TB(Impact Journals, 2017-03-24) Awoniyi, Dolapo O.; Baumann, Ralf; Chegou, Novel N.; Kriel, Belinda; Jacobs, Ruschca; Kidd, Martin; Loxton, Andre G.; Kaempfer, Susanne; Singh, Mahavir; Walzl, GerhardENGLISH ABSTRACT: 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 clinic attendees with signs and symptoms suggestive of TB. The sensitivity and specificity of IgA, IgG and/or IgM to LAM and 7 mycobacterial protein antigens (ESAT-6, Tpx, PstS1, AlaDH, MPT64, 16kDa and 19kDa) and 2 antigen combinations (TUB, TB-LTBI) in the plasma of 63 individuals who underwent diagnostic work-up for TB after presenting with symptoms and signs compatible with possible active TB were evaluated. Active TB was excluded in 42 individuals of whom 21 has LTBI whereas active TB was confirmed in 21 patients of whom 19 had a follow-up blood draw at the end of 6-month anti-TB treatment. The leading single serodiagnostic markers to differentiate between the presence or absence of active TB were anti-16 kDa IgA, anti-MPT64 IgA with sensitivity and specificity of 90%/90% and 95%/90%, respectively. The combined use of 3 or 4 antibodies further improved this performance to accuracies above 95%. After successful completion of anti-TB treatment at month 6, the levels of 16 kDa IgA and 16 kDa IgM dropped significantly whereas LAM IgG and TB-LTBI IgG increased. These results show the potential of extending investigation of anti-tuberculous IgG responses to include IgM and IgA responses against selected protein and non-protein antigens in differentiating active TB from other respiratory diseases in TB endemic settings.
- ItemDiffusion tensor imaging point to ongoing functional impairment in HIV-infected children at age 5, undetectable using standard neurodevelopmental assessments(BMC (part of Springer Nature), 2020-05-19) Ackermann, Christelle; Andronikou, Savvas; Saleh, Muhammad G.; Kidd, Martin; Cotton, Mark F.; Meintjes, Ernesta M.; Laughton, BarbaraBackground: 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 white matter measures in regions showing HIV-related alterations will be associated with lower neurodevelopmental scores in specific domains related to the functionality of the affected tracts. Methods: DTI was performed on children in a neurodevelopmental sub study from the Children with HIV Early Antiretroviral (CHER) trial. Voxel-based group comparisons to determine regions where fractional anisotropy and mean diffusion differed between HIV+ and uninfected children were done. Locations of clusters showing group differences were identified using the Harvard–Oxford cortical and subcortical and John Hopkins University WM tractography atlases provided in FSL. This is a second review of DTI data in this cohort, which was reported in a previous study. Neurodevelopmental assessments including GMDS and Beery-Buktenica tests were performed and correlated with DTI parameters in abnormal white matter. Results: 38 HIV+ children (14 male, mean age 64.7 months) and 11 controls (4 male, mean age 67.7 months) were imaged. Two clusters with lower fractional anisotropy and 7 clusters with increased mean diffusion were identified in the HIV+ group. The only neurodevelopmental domain with a trend of difference between the HIV+ children and controls (p = 0.08), was Personal Social Quotient which correlated to improved myelination of the forceps minor in the control group. As a combined group there was a negative correlation between visual perception and radial diffusion in the right superior longitudinal fasciculus and left inferior longitudinal fasciculus, which may be related to the fact that these tracts, forming part of the visual perception pathway, are at a crucial state of development at age 5. Conclusion: Even directed neurodevelopmental tests will underestimate the degree of microstructural white matter damage detected by DTI. The visual perception deficit detected in the entire study population should be further examined in a larger study.
- ItemDistinct serum biosignatures are associated with different tuberculosis treatment outcomes(Elsevier, 2019) Ronachera, Katharina; Chegoua, Novel N.; Kleynhansa, Leanie; Siawayac, Joel F. Djoba; Du Plessis, Nelita; Loxton, Andre G.; Maasdorp, Elizna; Tromp, Gerard; Kidd, Martin; Stanleya, Kim; Kriela, Magdalena; Menezesa, Angela; Gutschmidta, Andrea; Van Der Spuya, Gian D.; Warrena, Robin M.; Dietzee, Reynaldo; Okweraf, Alphonse; Thielg, Bonnie; Belisleh, John T.; Cliffi, Jacqueline M.; Boomg, W. Henry; Johnsong, John L.; Van Heldena, Paul D.; Dockrelli, Hazel M.; Walzla, GerhardENGLISH ABSTRACT: 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 relapsed and 15 failed treatment patients from South Africa before and during therapy for pulmonary TB. Promising biosignatures were evaluated in a second cohort from Uganda/Brazil consisting of 17 relapse and 23 cured patients. Thirty markers changed significantly with different response patterns during TB treatment in cured patients. The serum biosignature distinguished cured from relapse patients and a combination of two clinical (time to positivity in liquid culture and BMI) and four immunological parameters (TNF-β, sIL-6R, IL-12p40 and IP-10) at diagnosis predicted relapse with a 75% sensitivity (95%CI 0.38–1) and 85% specificity (95%CI 0.75–0.93). This biosignature was validated in an independent Uganda/Brazil cohort correctly classifying relapse patients with 83% (95%CI 0.58–1) sensitivity and 61% (95%CI 0.39–0.83) specificity. A characteristic biosignature with value as predictor of TB relapse was identified. The repeatability and robustness of these biomarkers require further validation in well-characterized cohorts.
- ItemDoes money "buy" tolerance toward damage-causing wildlife?(Wiley, 2020-07-26) Kansky, Ruth; Kidd, Martin; Fischer, JoernThe Kavango-Zambezi Transfrontier Conservation Area supports large-scale migrations of wildlife that occur in a mixed agri-conservation landscape in five Southern African countries. Human–Wildlife Conflict is a key challenge and understanding the drivers of communities' willingness to coexist with wildlife is thus critical. Community based natural resource management (CBNRM) is a widely used economic approach to foster human-wildlife coexistence with the assumption that monetary benefits can “buy” tolerance by offsetting the disservices of living with wildlife. We tested this assumption and hypothesized that Namibians would be more tolerant towards wildlife than Zambians because they received higher monetary benefits from wildlife. We used the Wildlife Tolerance Model (WTM) as the framework to define tolerance and identify tolerance drivers. We found Namibians tolerance was higher for lion, elephant and hyena but not for kudu and baboon. After controlling for confounding variables of the WTM that could potentially explain differences in tolerance, contrary to expectation, the monetary benefits did not account for higher Namibian tolerance. Instead, only nonmonetary benefits explained the higher tolerance. We used crowding theory to explain this finding, proposing that CBNRM in Namibia and the monetary benefits from the program “crowd in” intrinsic motivation to appreciate and tolerate wildlife.
- ItemThe effect of a rhythmic movement intervention on selected bio-motor skills of academy players in the Western Cape, South Africa(SAGE, 2020) Solomons, Jocelyn; Kraak, Wilbur Julio; Kidd, Martin; Africa, Eileen KatherineRhythmic movement, also referred to as “dance”, involves the execution of different motor skills as well as the integration and sequencing of actions between limbs, timing and spatial precision. The aim of this study was therefore to investigate and compare the effect of a 16-week rhythmic movement intervention on flexibility, dynamic balance, agility, power and local muscular endurance of academy rugby players in the Western Cape, according to positional group. Players (N=54) (age 18.66 ± 0.81 years; height 1.76 ± 0.69 cm; weight 76.77 ± 10.69 kg), were randomly divided into a treatment-control [TCA] (n=28) and a control-treatment [CTB] (n=26) group. In this crossover experimental design, the interaction effect of the treatment order and the treatment time between the TCA and CTB group, was determined. Results indicated a statistically significant improvement (p<0.05) in agility2 (p=0.06), power2 (p=0.05), local muscular endurance1 (p=0.01) & 3 (p=0.01) and dynamic balance (p<0.01). Likewise, forwards and backs also showed statistically significant improvements (p<0.05) per positional groups. Therefore, a rhythmic movement intervention has the potential to improve rugby-specific bio-motor skills and furthermore, improve positional specific skills should it be designed with positional groups in mind. Future studies should investigate, not only the effect of rhythmic movement on improving specific rugby bio-motor skills, but the potential of its application as an alternative training method during off-season (or detraining phases) or as a recovery method.
- ItemEffect of saccharomyces, non-saccharomyces yeasts and malolactic fermentation strategies on fermentation kinetics and flavor of Shiraz Wines(MDPI, 2017) Du Plessis, Heinrich; Du Toit, Maret; Nieuwoudt, Helene; Van der Rijst, Marieta; Kidd, Martin; Jolly, NeilThe 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, Lachancea, Metschnikowia and Torulaspora in combination with S. cerevisiae and three malolactic fermentation (MLF) strategies in a Shiraz winemaking trial. Standard oenological parameters, volatile composition and sensory profiles of wines were investigated. Wines produced with non-Saccharomyces yeasts had lower alcohol and glycerol levels than wines produced with S. cerevisiae only. Malolactic fermentation also completed faster in these wines. Wines produced with non-Saccharomyces yeasts differed chemically and sensorially from wines produced with S. cerevisiae only. The Candida zemplinina and the one L. thermotolerans isolate slightly inhibited LAB growth in wines that underwent simultaneous MLF. Malolactic fermentation strategy had a greater impact on sensory profiles than yeast treatment. Both yeast selection and MLF strategy had a significant effect on berry aroma, but MLF strategy also had a significant effect on acid balance and astringency of wines. Winemakers should apply the optimal yeast combination and MLF strategy to ensure fast completion of MLF and improve wine complexit
- ItemFive year neurodevelopment outcomes of perinatally HIV-infected children on early limited or deferred continuous antiretroviral therapy(Wiley Open Access, 2018) Laughton, Barbara; Cornell, Morna; Kidd, Martin; Springer, Priscilla Estelle; Dobbels, Els; Van Rensburg, Anita Janse; Otwombe, Kennedy; Babiker, Abdel; Gibb, Diana M.; Violari, Avy; Kruger, Mariana; Cotton, Mark F.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 (CHER) trial, HIVinfected infants ≤12 weeks of age with CD4 ≥25% were randomized to deferred ART (ART-Def); immediate time-limited ART for 40 weeks (ART-40W) or 96 weeks (ART-96W). ART was restarted in the time-limited arms for immunologic/clinical progression. Our objective was to compare the neurodevelopmental profiles in all three arms of Cape Town CHER participants. Methods: A prospective, longitudinal observational study was used. The Griffiths mental development scales (GMDS), which includes six subscales and a global score, were performed at 11, 20, 30, 42 and 60 months, and the Beery-Buktenica developmental tests for visual motor integration at 60 months. HIV-exposed uninfected (HEU) and HIV-unexposed (HU) children were enrolled for comparison. Mixed model repeated measures were used to compare groups over time, using quotients derived from standardized British norms. Results: In this study, 28 ART-Def, 35 ART-40W, 33 ART-96W CHER children, and 34 HEU and 39 HU controls were enrolled. GMDS scores over five years were similar between the five groups in all subscales except locomotor and general Griffiths (interaction p < 0.001 and p = 0.02 respectively), driven by early lower scores in the ART-Def arm. At 60 months, scores for all groups were similar in each GMDS scale. However, Beery visual perception scores were significantly lower in HIV-infected children (mean standard scores: 75.8 ART-Def, 79.8 ART-40W, 75.9 ART-96W) versus 84.4 in HEU and 90.5 in HU (p < 0.01)). Conclusions: Early locomotor delay in the ART-Def arm resolved by five years. Neurodevelopmental outcomes at five years in HIV-infected children on early time-limited ART were similar to uninfected controls, apart from visual perception where HIVinfected children scored lower. Poorer visual perception performance warrants further investigation.
- ItemGlutamate dehydrogenase and glutamine synthetase are regulated in response to nitrogen availability in Myocbacterium smegmatis(BioMed Central, 2010-05) Harper, Catriona J; Hayward, Don; Kidd, Martin; Wiid, Ian; Van Helden, PaulBackground: The assimilation of nitrogen is an essential process in all prokaryotes, yet a relatively limited amount of information is available on nitrogen metabolism in the mycobacteria. The physiological role and pathogenic properties of glutamine synthetase (GS) have been extensively investigated in Mycobacterium tuberculosis. However, little is known about this enzyme in other mycobacterial species, or the role of an additional nitrogen assimilatory pathway via glutamate dehydrogenase (GDH), in the mycobacteria as a whole. We investigated specific enzyme activity and transcription of GS and as well as both possible isoforms of GDH (NAD+- and NADP+-specific GDH) under varying conditions of nitrogen availability in Mycobacterium smegmatis as a model for the mycobacteria. Results: It was found that the specific activity of the aminating NADP+-GDH reaction and the deaminating NAD+-GDH reaction did not change appreciably in response to nitrogen availability. However, GS activity as well as the deaminating NADP+-GDH and aminating NAD+-GDH reactions were indeed significantly altered in response to exogenous nitrogen concentrations. Transcription of genes encoding for GS and the GDH isoforms were also found to be regulated under our experimental conditions. Conclusions: The physiological role and regulation of GS in M. smegmatis was similar to that which has been described for other mycobacteria, however, in our study the regulation of both NADP+- and NAD+-GDH specific activity in M. smegmatis appeared to be different to that of other Actinomycetales. It was found that NAD+-GDH played an important role in nitrogen assimilation rather than glutamate catabolism as was previously thought, and is it's activity appeared to be regulated in response to nitrogen availability. Transcription of the genes encoding for NAD+-GDH enzymes seem to be regulated in M. smegmatis under the conditions tested and may contribute to the changes in enzyme activity observed, however, our results indicate that an additional regulatory mechanism may be involved. NADP+-GDH seemed to be involved in nitrogen assimilation due to a constitutive aminating activity. The deaminating reaction, however was observed to change in response to varying ammonium concentrations which suggests that NADP+-GDH is also regulated in response to nitrogen availability. The regulation of NADP+-GDH activity was not reflected at the level of gene transcription thereby implicating post-transcriptional modification as a regulatory mechanism in response to nitrogen availability.
- ItemHair-pulling does not necessarily serve an emotion regulation function in adults with trichotillomania(Frontiers Media, 2021) Lochner, Christine; Demetriou, Salome; Kidd, Martin; Coetzee, Bronwyne; Stein, Dan J.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 controls completed the Childhood Trauma Questionnaire (CTQ), Perceived Stress Scale (PSS), and Difficulties in Emotion Regulation Scale (DERS). Hair-pulling severity was measured with the Massachusetts General Hospital-Hair Pulling Scale. CTQ, PSS, and DERS total scores were compared across groups using ANCOVA and the correlation between hair-pulling severity and emotion dysregulation was determined. Regression analyses were used to estimate the association of CTQ and PSS totals with DERS, and to determine whether associations between predictors and dependent variable (DERS) differed across groups. Results: TTM patients reported higher rates of childhood trauma (p <= 0.01), perceived stress (p = 0.03), and emotion dysregulation (p <= 0.01). There was no association between emotion dysregulation and pulling severity (r = −0.02, p = 0.89). Perceived stress was associated with emotion dysregulation in both groups (p < 0.01), and no association between childhood trauma and emotion dysregulation in either group. Perceived stress was the only significant predictor of emotion dysregulation in both groups (F = 28.29, p < 0.01). Conclusion: The association between perceived stress and emotion dysregulation is not specific to TTM, and there is no association between emotion dysregulation and hair-pulling severity, suggesting that key factors other than emotion dysregulation contribute to hair-pulling. Alternative explanatory models are needed.
- ItemHost markers in Quantiferon supernatants differentiate active TB from latent TB infection : preliminary report(BioMed Central, 2009-05) Chegou, Novel N.; Black, Gillian F.; Kidd, Martin; Van Helden, Paul D.; Walzl, GerhardBackground: Interferon gamma release assays, including the QuantiFERON® TB Gold In Tube (QFT) have been shown to be accurate in diagnosing Mycobacterium tuberculosis infection. These assays however, do not discriminate between latent TB infection (LTBI) and active TB disease. Methods: We recruited twenty-three pulmonary TB patients and 34 household contacts from Cape Town, South Africa and performed the QFT test. To investigate the ability of new host markers to differentiate between LTBI and active TB, levels of 29 biomarkers in QFT supernatants were evaluated using a Luminex multiplex cytokine assay. Results: Eight out of 29 biomarkers distinguished active TB from LTBI in a pilot study. Baseline levels of epidermal growth factor (EGF) soluble CD40 ligand (sCD40L), antigen stimulated levels of EGF, and the background corrected antigen stimulated levels of EGF and macrophage inflammatory protein (MIP)-1β were the most informative single markers for differentiation between TB disease and LTBI, with AUCs of 0.88, 0.84, 0.87, 0.90 and 0.79 respectively. The combination of EGF and MIP-1β predicted 96% of active TB cases and 92% of LTBIs. Combinations between EGF, sCD40L, VEGF, TGF-α and IL-1α also showed potential to differentiate between TB infection states. EGF, VEGF, TGF-α and sCD40L levels were higher in TB patients. Conclusion: These preliminary data suggest that active TB may be accurately differentiated from LTBI utilizing adaptations of the commercial QFT test that includes measurement of EGF, sCD40L, MIP-1β, VEGF, TGF-α or IL-1α in supernatants from QFT assays. This approach holds promise for development as a rapid diagnostic test for active TB.
- ItemHow useful are clinical details in blunt trauma referrals for computed tomography of the abdomen?(AOSIS, 2020-04-22) Beviss-Challinor, Kenneth B.; Kidd, Martin; Pitcher, Richard D.Background: The relevance of clinical data included in blunt trauma referrals for abdominal computed tomography (CT) is not known. Objectives: To analyse the clinical details provided on free-text request forms for abdominal CT following blunt trauma and assess their association with imaging evidence of intra-abdominal injury. Method: A single-institution, retrospective study of abdominal CT scans was performed for blunt trauma between 01 January and 31 March 2018. Computed tomography request forms were reviewed with their corresponding CT images. Clinical details provided and scan findings were captured systematically. The relationship between individual clinical features and CT evidence of abdominal injury was tested using one-way cross tabulation and Fisher’s exact test. Results: One hundred thirty-nine studies met inclusion criteria. A wide range of clinical details was communicated. Only clinical abdominal examination findings (p = 0.05), macroscopic haematuria (p < 0.01), pelvic fracture or hip dislocation (p = 0.04) and positive focused assessment with sonography in trauma (p < 0.01) demonstrated an associated trend with abdominal injury. Conclusion: Key abdominal examination and basic imaging findings remain essential clinical details for the appropriate evaluation of CT abdomen requests in the setting of blunt trauma. Methods to improve consistent communication of relevant clinical details are likely to be of value.
- ItemThe impact of voluntary exercise on relative telomere length in a rat model of developmental stress(BioMed Central, 2012-12) Botha, Martmari; Grace, Laurian; Bugarith, Kishor; Russell, Vivienne A.; Kidd, Martin; Seedat, Soraya; Hemmings, Sian M. J.Background Exposure to early adverse events can result in the development of later psychopathology, and is often associated with cognitive impairment. This may be due to accelerated cell aging, which can be catalogued by attritioned telomeres. Exercise enhances neurogenesis and has been proposed to buffer the effect of psychological stress on telomere length. This study aimed to investigate the impact of early developmental stress and voluntary exercise on telomere length in the ventral hippocampus (VH) and prefrontal cortex (PFC) of the rat. Forty-five male Sprague–Dawley rats were categorised into four groups: maternally separated runners (MSR), maternally separated non-runners (MSnR), non-maternally separated runners (nMSR) and non-maternally separated non-runners (nMSnR). Behavioural analyses were conducted to assess anxiety-like behaviour and memory performance in the rats, after which relative telomere length was measured using qPCR. Results Maternally separated (MS) rats exhibited no significant differences in either anxiety levels or memory performance on the elevated-plus maze and the open field compared to non-maternally separated rats at 49 days of age. Exercised rats displayed increased levels of anxiety on the day that they were removed from the cages with attached running wheels, as well as improved spatial learning and temporal recognition memory compared to non-exercised rats. Exploratory post-hoc analyses revealed that maternally separated non-exercised rats exhibited significantly longer telomere length in the VH compared to those who were not maternally separated; however, exercise appeared to cancel this effect since there was no difference in VH telomere length between maternally separated and non-maternally separated runners. Conclusions The increased telomere length in the VH of maternally separated non-exercised rats may be indicative of reduced cellular proliferation, which could, in turn, indicate hippocampal dysfunction. This effect on telomere length was not observed in exercised rats, indicating that voluntary exercise may buffer against the progressive changes in telomere length caused by alterations in maternal care early in life. In future, larger sample sizes will be needed to validate results obtained in the present study and obtain a more accurate representation of the effect that psychological stress and voluntary exercise have on telomere length.
- ItemInternalizing mental disorders and accelerated cellular aging among perinatally HIV-infected youth in Uganda(Frontiers Media, 2019) Kalungi, Allan; Womersley, Jacqueline S.; Kinyanda, Eugene; Joloba, Moses L.; Ssembajjwe, Wilber; Nsubuga, Rebecca N.; Levin, Jonathan; Kaleebu, Pontiano; Kidd, Martin; Seedat, Soraya, 1966-; Hemmings, Sian M. J.Introduction: Internalizing mental disorders (IMDs) in HIV+ children and adolescents are associated with impaired quality of life and non-adherence to anti-retroviral treatment. Telomere length is a biomarker of cellular aging, and shorter telomere length has been associated with IMDs. However, the nature of this association has yet to be elucidated. Objective: We determined the longitudinal association between IMDs and relative telomere length (rTL) and the influence of chronic stress among Ugandan perinatally HIV-infected youth (PHIY). Methods: IMDs (depressive disorders, anxiety disorders, and post-traumatic stress disorder) and IMDs were assessed using the locally adapted Child and Adolescent Symptom Inventory-5. In 368 PHIY with any IMD and 368 age- and sex-matched PHIY controls without any psychiatric disorder, rTL was assessed using quantitative polymerase chain reaction. Hierarchical cluster analysis was used to generate the three chronic stress classes (mild, moderate, and severe). t-tests were used to assess the difference between baseline and 12 month rTL and the mean difference in rTL between cases and controls both at baseline and at 12 months. Linear regression analysis was used to model the effects of chronic stress on the association between IMDs and rTL, controlling for age and sex. Results: We observed longer rTL among cases of IMDs compared with controls (p < 0.001). We also observed a statistically significant reduction in rTL between baseline and 12 months in the combined sample of cases and controls (p < 0.001). The same statistical difference was observed when cases and controls were individually analyzed (p < 0.001). We found no significant difference in rTL between cases and controls at 12 months (p = 0.117). We found no significant influence of chronic stress on the association between IMDs and rTL at both baseline and 12 months. Conclusion: rTL is longer among cases of IMDs compared with age- and sex-matched controls. We observed a significant attrition in rTL over 12 months, which seems to be driven by the presence of any IMDs. There is a need for future longitudinal and experimental studies to understand the mechanisms driving our findings.
- ItemJob crafting, proactive personality and meaningful work : implications for employee engagement and turnover intention(AOSIS, 2019) Vermooten, Nicola; Boonzaier, Billy; Kidd, MartinOrientation : Jobs in the financial services industry are in constant flux because of the ever-changing nature of the products and services provided to customers. This could result in employee disengagement and turnover intention. Research purpose: The purpose of the study was to examine the role of job crafting, proactive personality and meaningful work in predicting employee engagement and turnover intention among employees in the financial services industry based on the central tenets of the Job Demands-Resources theory. Motivation for the study: Organisations or incumbents may redesign jobs. The self-initiated proactive behaviour that incumbents exhibit to shape the meaning of their work is known as job crafting. The relationships that exist among job crafting, proactive personality, meaningful work, employee engagement and turnover intention were, therefore, investigated. Research design, approach and method: A quantitative cross-sectional survey design was used to gather primary data in service-providing firms across South Africa (n = 391). Main findings: Results demonstrated that job crafting, proactive personality and meaningful work significantly predict variance in employee engagement and turnover intention. Practical and managerial implications: Specific human resource practices and interventions are proffered to foster job crafting, proactivity and meaningful work and, in doing so, address employee disengagement and turnover intention. Contribution or value-add: The study highlights the importance of encouraging employees to craft their jobs as it has specific implications for prominent work-related outcomes, such as employee engagement and turnover intention, among employees in the financial services industry.