Research Output - SU Research Articles
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- ItemCirculating Growth Differentiation Factor 15 Is Increased Preceding Preeclampsia Diagnosis: Implications as a Disease Biomarker(Wolters Kluwer, 2021-08-17) Cruickshank, Tess; MacDonald, Teresa M; Walker, Susan P; Keenan, Emerson; Dane, Kirsten; Middleton, Anna; Kyritsis, Valerie; Myers, Jenny; Cluver, Catherine; Hastie, Roxanne; Bergman, Lina; Garcha, Damanpreet; Cannon, Ping; Murray, Elizabeth; Nguyen, Tuong‐Vi; Hiscock, Richard; Pritchard, Natasha; Hannan, Natalie J; Tong, Stephen; Kaitu’u‐Lino, Tu’uhevaha JBackground We investigated the biomarker potential of growth differentiation factor 15 (GDF-15), a stress response protein highly expressed in placenta, to predict preeclampsia. Methods and Results In 2 prospective cohorts (cohort 1: 960 controls, 39 women who developed preeclampsia; cohort 2: 950 controls, 41 developed preeclampsia), plasma concentrations of GDF-15 at 36 weeks' gestation were significantly increased among those who developed preeclampsia (P<0.001), area under the receiver operating characteristic curves (AUC) of 0.66 and 0.71, respectively. In cohort 2 a ratio of sFlt-1/PlGF (a clinical biomarker for preeclampsia) had a sensitivity of 61.0% at 83.2% specificity to predict those who will develop preeclampsia (AUC of 0.79). A ratio of GDF-15×sFlt-1/PlGF yielded a sensitivity of 68.3% at 83.2% specificity (AUC of 0.82). GDF-15 was consistently elevated across a number of international cohorts: levels were higher in placenta and blood from women delivering <34 weeks' gestation due to preterm preeclampsia in Melbourne, Australia; and in the blood at 26 to 32 weeks' gestation among 57 women attending the Manchester Antenatal Vascular Service (MAViS, UK) who developed preeclampsia (P=0.0002), compared with 176 controls. In the Preeclampsia Obstetric adVerse Events biobank (PROVE, South Africa), plasma GDF-15 was significantly increased in women with preeclampsia with severe features (P=0.02; n=14) compared to controls (n=14). Conclusions We conclude circulating GDF-15 is elevated among women more likely to develop preeclampsia or diagnosed with the condition. It may have value as a clinical biomarker, including the potential to improve the sensitivity of sFlt-1/PlGF ratio.
- ItemMinor Histories of the Pacific [Special Section](2012-05) Mishra, Sudesh; Smith, Russell
- ItemNovel Paraconiothyrium species on stone fruit trees and other woody hosts(Naturalis Biodiversity Center, 2008-06) Damm, U; Verkley, GJM; Crous, PW; Fourie, PH; Haegi, A; Riccioni, LConiothyrium-like fungi are common wood and soil inhabitants and hyperparasites on other fungi. They belong to different fungal genera within the Pleosporales. Several isolates were obtained on wood of different Prunus species (plum, peach and nectarine) from South Africa, on Actinidia species from Italy and on Laurus nobilis from Turkey. Morphological and cultural characteristics as well as DNA sequence data (5.8S nrDNA, ITS1, ITS2, partial SSU nrDNA) were used to characterise them. The isolates belonged to three species of the recently established genus Paraconiothyrium. This is the first report of Paraconiothyrium brasiliense on Prunus spp. from South Africa. Two new species are described, namely Paraconiothyrium variabile sp. nov. on Prunus persica and Prunus salicina from South Africa, on Actinidia spp. from Italy and on Laurus nobilis from Turkey, and Paraconiothyrium africanum sp. nov. on Prunus persica from South Africa. Although other known species of Paraconiothyrium commonly produce aseptate conidia, those of P. africanum and P. hawaiiense comb. nov. are predominantly two-celled. © 2008 Nationaal Herbarium Nederland.
- ItemParticle filtering on hybrid dynamical systems for sensor fault detection(Elsevier, 2024) Loubser, Simone D; Louw, Tobias M; Bradshaw, Steven M
- ItemPotential tipping points for climate change adaptation costs(Taylor & Francis, 2023-09-14) Midgley, Guy F; Chapman, R Arthur; Araujo, JulioThe achievement of adaptation objectives will require increased investment with the increasing warming, but adaptation cost curves are not yet well quantified. We propose here that tipping points (sharp increases) in adaptation costs may emerge as key warming levels are exceeded, with important implications for policymakers and planners. We explore this proposition using selected African agriculture and ecosystem-based livelihoods examples, considering how adaptation responses might progress from a coping phase (with low-cost efforts), through a tipping point into a phase of proactive or planned (‘incremental’) adaptation that requires a sharp increase in adaptation investment, and through a further tipping point into a technology and capital-intensive (‘transformative’) phase requiring a further sharp increase in investment. Tipping points in adaptation costs may result as a series of limits to adaptation are breached, but the associated sharp cost transitions are not well recognized in the literature. Adaptation research could usefully focus on identifying the likely timing of these tipping points and in what sectors they may occur. Emerging analyses of joint mitigation/adaptation response options may need to account for these tipping points.
- ItemPowder rheology and characterization of new and zinc recycled WC-6wt%Co powders(Elsevier, 2024-09) Freemantle, CS; Sacks, NFour industrially manufactured WC-6wt%Co powders were studied in terms of bulk properties, morphology and powder rheology. Two powders, comprising 100 % fresh raw material, a 100 % zinc recycled powder and a powder comprising 60 wt% zinc recycled and 40 wt% new material, were investigated. The powders were produced from both laboratory and production mills utilizing a typical powder metallurgical process route, that produced spherically shaped, granulated powders in the 45-212 μm size range. Powder screen fractions of 45-63 μm, 90-125 μm and 150-180 μm were studied in detail using an FT4 powder rheometer as well as optical and scanning electron microscopy. Apparent density, flow rate tests and powder rheology revealed that dense granules behaved most consistently, with the smallest differences in flow rates, density and flow energy for differently sized particles, compared to hollow granules. New powder and 100 % zinc recycled powder of the 45-63 μm size range were exposed to 75 % relative humidity for 24 h and experienced higher cohesion, high flow energies and poor rheological behaviour compared to dry powders, independent of their recycling history. Shear and friction tests could not distinguish the powders clearly, while dynamic analysis, aeration, de-aeration, permeability and compressibility tests revealed that the powders' flow energy and response to air depended primarily on particle size and the presence of fines. Zinc recycled powders behaved the same way as new powders if their granule microstructure and particle size distribution was the same, with the formation of ideal dense granules resulting from slurries spray dried with a high yield stress.
- ItemSequential extraction of protein and inulin from the tubers of Jerusalem artichoke (Helianthus tuberosus L.)(Springer Nature, 2020-02) Maumela, Pfariso; Van Rensburg, Eugéne; Chimphango, Annie FA; Gorgens, Johann FAn increase in inulin and plant-protein based nutraceutical demand ultimately puts pressure on available resources. Therefore, there is a need to prospect for supplementary feedstocks and sustainable ways to exploit them. The aim of this study was to explore the technical feasibility of sequential extraction of inulin and protein from Jerusalem artichoke tubers and understand the interrelationships between processes and product functional properties. The response surface methodology was used to determine the optimal parameters for sequential extraction. Protein functional properties analysis was done to identify the effects of the extraction process. The extraction approach adopted in this study was preceded by mechanical pressing of the tuber to yield a protein-rich juice. However, only 40.8% of the protein was recovered from the juice, therefore a subsequent solvent extraction step followed to extract the residual protein and inulin retained in the solids. Selective extraction was achieved when protein was solubilised in the first step of solvent extraction. The overall protein and inulin yields from pressing and both sequential extraction steps were 71.88 and 67.6%, respectively. The inulin yields were substantially higher than the maximum overall yields when inulin extraction, from the pressed tuber, was performed first thus improving yields from 57.3 to 67.6%. Consequently, mechanical pressing improved the overall protein yield. Sequential extraction resulted in an inulin extract with minimal protein contamination compared to the conventional method. Therefore, sequential extraction was efficient in yielding extracts with reduced impurities and good functional properties.
- ItemStructural controls on mineralisation at the Namib Lead and Zinc Mine, Damara Belt, Namibia(Elsevier, 2018-04) Basson, IJ; McCall, M-J; Andrew, J; Daweti, EThe Namib Lead and Zinc (Pb-Zn) Mine is hosted within the Karibib Formation of the Swakop Group, Damara Sequence. The host marble contains sulphide-rich beds and is locally Pb- and Zn-rich over a strike extent of >100 km. Mining took place in the upper portions of a remobilized MVT or SEDEX orebody, which may occur adjacent to a reactivated major structure. Pb and Zn show locally anomalous copper, tin, indium and fluorine concentrations. Based on the position of gossans, individual orebodies comprise discrete elongate shoots around an antiform and its meso-scale parasitic folds, within calcitic marble. Non-coaxial flattening of the fold-cleavage geometry reflects a series of non-coaxial deformation events, recorded in the Southern Central Zone of the Damara Belt which were superimposed on a NE-SW structural grain and pre-existing fold axial planes. Non-coaxial flattening resulted in further remobilization of sulphides into dilational rhombs which formed from shearing along overlapping axial planar cleavage, in concert with the dilation of banding in the host marble.
- ItemStructural controls on mineralisation at the Namib Lead and Zinc Mine, Damara Belt, Namibia(Elsevier, 2018-04) Basson, IJ; McCall, M-J; Andrew, J; Daweti, EThe Namib Lead and Zinc (Pb-Zn) Mine is hosted within the Karibib Formation of the Swakop Group, Damara Sequence. The host marble contains sulphide-rich beds and is locally Pb- and Zn-rich over a strike extent of >100 km. Mining took place in the upper portions of a remobilized MVT or SEDEX orebody, which may occur adjacent to a reactivated major structure. Pb and Zn show locally anomalous copper, tin, indium and fluorine concentrations. Based on the position of gossans, individual orebodies comprise discrete elongate shoots around an antiform and its meso-scale parasitic folds, within calcitic marble. Non-coaxial flattening of the fold-cleavage geometry reflects a series of non-coaxial deformation events, recorded in the Southern Central Zone of the Damara Belt which were superimposed on a NE-SW structural grain and pre-existing fold axial planes. Non-coaxial flattening resulted in further remobilization of sulphides into dilational rhombs which formed from shearing along overlapping axial planar cleavage, in concert with the dilation of banding in the host marble.
- ItemTest submission mimicking the DSpace API deposit from Symplectic Elements(Cape Town publishers, 2024-10-17) Klapwijk, WKThis is a test submission.
- ItemToll-like receptor pathways in the immune responses to mycobacteria(Elsevier, 2004-08) Quesniaux, Valerie; Fremond, Cecile; Jacobs, Muazzam; Parida, Shreemanta; Nicolle, Delphine; Yeremeev, Vladimir; Bihl, Franck; Erard, Francois; Botha, Tania; Drennan, Michael; Soler, Marie-Noelle; Le Bert, Marc; Schnyder, Bruno; Ryffel, BernhardThe control of Mycobacterium tuberculosis infection depends on recognition of the pathogen and the activation of both the innate and adaptive immune responses. Toll-like receptors (TLR) were shown to play a critical role in the recognition of several pathogens. Mycobacterial antigens recognise distinct TLR resulting in rapid activation of cells of the innate immune system. Recent evidence from in vitro and in vivo investigations, summarised in this review demonstrates TLR-dependent activation of innate immune response, while the induction of adaptive immunity to mycobacteria may be TLR independent. © 2004 Elsevier SAS. All rights reserved.