1834 research outputs found
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Synthesis, characterization and anticancer studies of Osmium-cymene complexes with O,O'- and P,P'-chelators as well as monodentate N- and P-donar ligands
No full textSeventeen novel osmium cymene complexes with O,O′- and P,P′-chelating ligands as well as N- and P-monodentate ligands are reported. The osmium cymene complexes were synthesised and characterised by spectroscopic techniques (NMR, IR and Raman), elemental analysis, thermal analysis, conductivity studies and X-ray crystallography. The molecular structures of complexes 1(b), 2, 4, 6, 7(a)-(d) and 11 in this study are reported. The cymene rings of these complexes show different conformations due to loss of planarity influenced by the ancillary ligands as a result of ML back bonding.
Osmium cymene complexes of the type [Os(η6-p-cymene)BrL2]+ (where L2 = chelating P,P′ ligand) and binuclear [{Os(η6-p-cymene)Br2}2 L2] (where L2 = bridging P,P′ ligand) were evaluated for anticancer activity against renal, melanoma, breast and HeLa cancer cells. The chelated-diphosphine osmium cymene complexes exhibited significant anticancer activities relative to the bridged-diphosphine osmium analogues. A series of O,O′-chelated osmium complexes exhibited moderate and poor anticancer activities.National Research Foundatio
Exploring resilience capacities through the art of storymaking: the case of food innovators in the Western Cape
No full textThis project explores the potential of storymaking as a novel methodology
for developing insight into the ways in which a small selection of social
innovators are working to shape change in the food system of the
Western Cape, South Africa, and particularly some of the different
capacities they are drawing on that may contribute to resilience.
Current literature on the Anthropocene, a proposed new geological era in
which human agency is seen as a driving force impacting planetary
systems, recognises social-ecological resilience theory as an emerging
approach to dealing with unexpected change. This thesis brings a
narrative and interpretative lens to the experiences of five social
innovators who are working towards social-ecological change in the food
system of the Western Cape and are part of the international Seeds of the
Good Anthropocene project. The Seeds of the Good Anthropocene
research seeks to analyse the potential of selected small-scale socialecological
projects to help accelerate transformations towards positive
futures for people and planet.
In this project, the stories of food innovators are analysed through a
‘storymaking’ process of in-depth interviews, narrative inquiry and
interpretative phenomenological analysis. In this process, a richness of
experience and meaning that surfaces in the stories shared by research
participants is explored, with the aim of understanding whether interpreting these stories through different resilience frames can help to
provide insight into the capacities that contribute towards resilience.
This work conceptualises the Western Cape as an ‘Anthropocene space’,
with a unique historical and geographical context in which multiple food
system crises are reflected, thus creating conditions ripe for
transformation. Against this backdrop, the work connects the stories of
social innovators in food to social-ecological resilience themes of
rootedness, resourcefulness and resistance. It also connects these reallife
stories and themes to a more theoretical exploration of the complex
relationships between stories, resilience, agency and transformation.
What emerges is a picture of social innovators experimenting and
connecting with one another, guided by rich and emerging value systems,
working along the ‘unruly edges’ and the generative niches in between
more formal institutions, practices and ways of thinking, transforming
these spaces through their alternative narratives of food, culture and
community, and in the process deeply exploring questions of how to
reconnect with nature and ourselves, and how to live well in the
Anthropocene.National Research Foundatio
Genetic diversity and identification of putative recombination events in Grapevine rupestris stem pitting-associated virus
No full textNational Research Foundatio
Stem cell impairment associated with type 2 diabetes mellitus : investigating the effects of obesity-associated inflammation on mesenchymal stem cell function
No full textNational Research Foundatio
Low leopard populations in protected areas of Maputaland: a consequence of poaching, habitat condition, abundance of prey and a top predator
No full textIdentifying the primary causes affecting population densities and distribution of flagship species are necessary in developing sustainable management strategies for large carnivore conservation. We modeled drivers of spatial density of the common leopard (Panthera pardus) using a spatially explicit capture–recapture—Bayesian approach to understand their population dynamics in the Maputaland Conservation Unit, South Africa. We camera‐trapped leopards in four protected areas (PAs) of varying sizes and disturbance levels covering 198 camera stations. Ours is the first study to explore the effects of poaching level, abundance of prey species (small, medium, and large), competitors (lion Panthera leo and spotted hyenas Crocuta crocuta), and habitat on the spatial distribution of common leopard density. Twenty‐six male and 41 female leopards were individually identified and estimated leopard density ranged from 1.6 ± 0.62/100 km2 (smallest PA—Ndumo) to 8.4 ± 1.03/100 km2 (largest PA—western shores). Although dry forest thickets and plantation habitats largely represented the western shores, the plantation areas had extremely low leopard density compared to native forest. We found that leopard density increased in areas when low poaching levels/no poaching was recorded in dry forest thickets and with high abundance of medium‐sized prey, but decreased with increasing abundance of lion. Because local leopard populations are vulnerable to extinction, particularly in smaller PAs, the long‐term sustainability of leopard populations depend on developing appropriate management strategies that consider a combination of multiple factors to maintain their optimal habitatsNational Research Foundation (South Africa
Investigating plasmepsin flexibility as a function of the flap region : a unique structural and dynamic feature of aspartic protease.
No full textMalaria is one of the most deadly infectious protozoan diseases known to man. It is spread by the Plasmodium parasite through the bite of the female Anopheles mosquito. Increasing resistance to currently available antimalarial drugs is a growing concern. Plasmepsins are malarial aspartic proteases, due to their characteristic mechanism of action, the fact that they are found in all Plasmodium species and are essential to parasitic survival they represent novel targets in the design of antimalarials. A unique structural feature of aspartic proteases and plasmepsins is the flap region lying perpendicular to the catalytic aspartic acid active, partially covering the active site. The flap region plays an important structural (and kinetic) role in regulating access to the active site, thereby regulating ligand binding.
The present study focused on the flap dynamics of Plm I – V, proposing and validating parameters to accurately quantify the dynamic behaviour of the flap region. The catalytic aspartic acids is highly conserved in the plasmepsin family; sequence analysis revealed that although all plasmepsins are similar in structure, they differ greatly in the residues in the flap region. The heterogeneity in this region gives each plasmepsin unique substrate specificity and response to inhibitors. The parameters proposed in the present study gives a detailed account for the twisting of the flaps which move away from the active site in the absence of an inhibitor. Upon inhibitor binding, residues in the flap region form hydrogen bonds with the inhibitor pulling it inward towards the active site rendering the enzyme inactive. The parameters proposed in the present study will be of great value in the design of novel plasmepsin inhibitors, with increased efficacy and potency.National Research Foundatio
The authentication of regionally unique South African lamb
No full textNoted for its unique herbaceous flavour which is imbued from a diet of indigenous fragrant plants, Karoo lamb is
marketed as one of South Africa’s finest meat products. It is also the first fresh meat product to receive Protected
Geographical Indication (PGI) status in South Africa. Its distinct quality is imparted through natural grazing of the
sheep on the Karoo veld of the Northern parts of the country. Although it is considered common knowledge to South
Africans that Karoo lamb is different to that of lamb meat from other regions, there is a lack of scientific evidence to
verify these claims. In order for Karoo lamb to receive official recognition and protection as an authentic product, it
is vital to confirm such claims. The aim of the study was to validate the authentic nature of regionally unique South
African lamb using analytical techniques. Emphasis was placed on Karoo lamb, while the characteristics of other
region of origin lamb, such as the Rûens and Free State lamb, were also determined. A key aspect of the study was
to link the characteristic diet, related to its origin, to the sensory and chemical profiles of the meat and fat.
The findings show that diet plays an integral part in the sensory characteristics of Karoo lamb meat and hence,
have a significant influence on the sensory and chemical profile of South African lamb. Descriptive sensory analysis
(DSA), fatty acid analysis, solid-phase microextraction (SPME), isotope ratio mass spectrometry (IRMS), nearinfrared
reflectance spectroscopy (NIRS) (using a portable MicroNIR spectrometer) and proton transfer reactionmass
spectrometry (PTR-MS) proved to be very successful analytical tools for the authentication of lamb,
distinguishing Karoo from Non-Karoo lamb.
A key finding was the detection of volatiles, specifically terpenes, present in both the Karoo bushes and the
Karoo lamb meat and fat. Terpenes were prominent in the fat tissue and detected at mass ratios m/z 81 and m/z
137 using PTR-MS. The dominant terpenes were tentatively identified as α-pinene, β-pinene, limonene and transcaryophyllene
using SPME. The highest concentrations of terpenes were detected in Karoo lamb, while the NonKaroo
lamb did not or hardly contained any. Within the Karoo, regional differences were apparent as Hantam Karoo
lamb had the highest ratings for herbaceous aroma and flavour and contained the greatest concentration of terpenes.
Therefore, it is proposed that Karoo lamb is marketed according to its region of origin. Herbaceous aroma and
flavour attributes associate with a diet rich in fragrant Karoo plants which were verified with stable isotope ratio
analysis. The stable isotopic ratios were indicative of the extensive grazing diet of the animals where discrimination
between diets composed of grass, Karoo bushes, lucerne/alfalfa (Medicago sativa) and a combination of grass and
Karoo bushes were achieved. The results confirm that Karoo bushes are responsible for the distinct aroma and
flavour of Karoo lamb. Hence, the results serve as evidence for its certification and justify the protection of its
indicator status.
It is recommended that the meat industry utilise the value linked to origin and invest in the marketing of
regionally unique lamb. In order to prevent fraudulence and the misuse of protected names, the meat industry
should also implement NIRS and PTR-MS as a rapid and effective origin based testing method. The combination
of these two techniques improves the discriminative power and allows reliable origin classification.National Research Foundatio
Optimization of the experimental conditions and analysis tools for the study of the phosphodiesterase-5 in a model of cultured adult rat cardiomyocytes
No full textPart 1
Introduction: Phosphodiesterases (PDEs) hydrolyse cyclic nucleotides that regulate ischemiareperfusion
injury (IRI) in the heart. Phosphodiesterases-5 (PDE5) inhibition increases cyclic
guanosine monophosphate (cGMP) levels and thereby promotes cardioprotection. Cannabidiol is a
cannabinoid that can alter cGMP levels and induced protection in whole hearts. Cannabidiol-mediated
cardioprotection might be controlled by specific PDEs, possibly PDE5.
This study aimed to:
Evaluate the role of PDE5 inhibition in IRI.
Determine whether PDE5 plays a role in cannabidiol-mediated protection.
Methods: Cultured adult rat cardiomyocytes were subjected to 20 minutes ischemia, 60 minutes
reperfusion, which included mitochondrial staining to measure mitochondrial function with JC-1,
followed by fluorescence microscopy and image analysis. A cardioprotective dose of cannabidiol and
time of intervention was sought by administration of cannabidiol (0.001 μM, 1 μM and 100 μM) during
ischemia and reperfusion, only ischemia, and only reperfusion, respectively. 10 μM Sildenafil was
administered during ischemia only to inhibit PDE5.
Results: Ischemia-reperfusion reduced cell viability according to morphology by 79 % and
mitochondrial function by 50 %. None of the treatments induced cardioprotection.
Conclusion: The lack of cardioprotection from cannabidiol and sildenafil might have been due to (1)
the ischemic conditions being too harsh, (2) the analysis program being faulty, or (3) unreliable data
from morphology analysis. These three points of concern became the basis for the new objectives
investigated in Part 2 of this thesis.
Part 2
Introduction: Cell viability and mitochondrial function are parameters normally evaluated in
cardiomyocytes, and were also used in this study, but cardioprotection could not be found. This raised
concerns about the reliability of the image analysis program (ImageJ), the severity of ischemia, and
the reliability of the parameters measured. The method used to determine cell viability was especially
questioned, because it relies on the researcher to classify rod cells as viable and round cells as dead,
which is thus subjective. Morphometry analysis with length over width (L/W) removes the human
aspect, allowing cell viability to be determined by classifying cardiomyocytes with L/W ≥ 1.5 as viable.
Length on its own is also a morphometric measurement, but is seldom used.
Part 2 of this study aimed to:
Compare image analysis of ImageJ with that of CellProfiler.
Optimize conditions for ischemia-reperfusion and hypoxia-reperfusion.
Compare morphology analysis with morphometry analysis.
Methods: The sildenafil experimental images from Part 1 were reanalyzed using CellProfiler and the
data compared with that found with ImageJ. Ischemia-reperfusion was induced with less harsh
conditions for 1 hour, and compared to hypoxia-reperfusion, using cell viability and mitochondrial
function. Cell viability was determined by selecting viable cells by rod shape, compared to L/W ≥ 1.5,
and length ≥ 55 μm. The average length for hypercontracted cells in the normoxic population was
determined, and found to be consistently below 55 μm. Length ≥ 55 μm was chosen as morphometry
selection to identify viable cells.
Results: Both ImageJ and CellProfiler provided similar data. Cell viability for L/W ≥ 1.5 and
length ≥ 55 μm were similar, but higher than morphology, especially for hypoxia-reperfusion, but not
for ischemia-reperfusion. L/W ≥ 1.5 and length ≥ 55 μm found differences between normoxia and
hypoxia-reperfusion, unlike morphology. The differences can be explained by morphology selecting
fewer cells that are perfectly healthy, while morphometry selects more cells with varying degrees of
cell injury. Only for ischemia-reperfusion did all parameters provide similar knockdown. This can be
explained by ischemia-reperfusion that induced severe injury and hypoxia-reperfusion that induced
less injury.
Conclusion: The lack of cardioprotection by PDE5 inhibition and cannabidiol was not due to an image
analysis error by the program, but might rather be due to ischemia-reperfusion that was too harsh.
Conversely, hypoxia-reperfusion induced injury that was not harsh enough. Morphometry selection is
biased and unreliable, and morphometry selection should rather be used to evaluate an injured
cardiomyocyte population.National Research Foundatio
ICT readiness for business continuity in local government
No full textInformation and Communication Technology (ICT) has evolved into a pervasive commodity in modern enterprises. ICT enables enterprises, regardless of sector, to achieve their strategic objectives. Similarly, ICT is regarded as a critical enabler in South African municipalities to reach their objectives and ultimately deliver sustainable services to their communities. This dependence on ICT, therefore, necessitates a resilient ICT environment where minimal disruption to ICT is a primary goal. Unfortunately, as reported by the Auditor-General of South Africa, the majority of South African municipalities are neglecting to address the continuity of their ICT services. Failing to implement adequate ICT continuity controls restrict these municipalities from achieving their strategic goals and, as a result, fulfilling their constitutional mandate of service delivery. It is, therefore, the objective of this study to devise a method, consisting of a theoretical foundation and a supporting tool-set, to assist municipalities in addressing a real-world ICT continuity problem. This method aims to be scalable and usable within different municipalities, and be simplistic and comprehensible enough to implement. The theoretical foundation will introduce the concept of ICT Readiness for Business Continuity, based on the recommendations of international best practices and standards, for example, the ISO 27031 (2011) standard. Furthermore, by considering various challenges within local government, the tool-set will ultimately help municipalities to help themselves in this regard.National Research Foundatio
A framework for the corporate governance of ICT in local government
No full textInformation and Communication Technology (ICT) has become critical and
pervasive in any well-run modern enterprise across all sectors, which include
local government. As a result, ICT demands to be managed and governed
in a sustainable manner. Therefore, local government should accept the responsibility
of implementing good Corporate Governance of ICT (CGICT).
Without sound CGICT, ICT is unable to support local government in the
achievement of their strategic objectives. This will most likely result in local
government not being able to serve the interests of the community. Even
though local government is aware of their responsibility regarding CGICT,
the Auditor-General reports that their attempts are unsatisfactory, in this
regard. This is most probably due to the fact that ample information exists
on guiding local government with ‘what’ they should do towards good
CGICT, but unfortunately a lack of guidance on ‘how’ to achieve it. Thus, it
is imperative for local government to adopt a CGICT framework which provides
guidance not only on what they must do towards implementing good
CGICT but also on how they should achieve it. In doing so, local government
would most likely be able to properly manage and govern ICT and support
the needs of the community. Therefore, the aim of this study is to report
on research undertaken, in order to assist local government with a CGICT
framework that is relevant to their unique environment. Accordingly, this
CGICT framework aims to be usable and scalable to fit the needs of any
sized local government entity. As a result, the CGICT framework aims to
be simplistic in nature to promote self-implementation of sound CGICT in
local government.National Research Foundatio