Environmental Factors That Affect The Abundance of Larval Mosquitoes

The development of stormwater infrastructure causes an increase in available aquatic habitat for mosquito breeding and larval development, posing drastic human health consequences. It has been observed that a diverse community of predators have been found to decrease mosquito abundance1. Multiple species coexisting with mosquitos was found to decrease the percentage of mosquitoes in wet water communities, strongly highlighting the role that zooplankton play in the assembly of aquatic communities2. Studying stormwater communities will help determine the main contributors to why mosquitoes oviposit in certain urban stormwater ponds.Ope

Effects of irradiation on the cowpea weevil (Callosobruchus maculates F.) and moisture sorption isotherm of cowpea seed (Vigna unguiculata L. Walp)

Cowpeas during storage may be attacked by a number of biological agents (microorganisms, rodents, and insects) which results in losses in the quality and quantity of the stored seeds. One of the means of reducing these losses is through the application of radiation processing. The aim of this study was to determine the effects of gamma irradiation on a major storage insect pest, Callosobruchus maculatus F. and on moisture sorption isotherms of cowpea seeds in storage. The cowpeas were infested with adults C. maculatus and then irradiated at doses of 0.0, 0.25, 0.5, 0.75, 1.0 and 1.5 (kGy) at a dose rate of 1.074 kGyhr-1. Samples were stored for 1 month under controlled temperature (27.3-30 oC) and humidity (70-85 %) during which counting of the insects was done every 48 hours and those alive or dead noted. Moisture sorption isotherms of the cowpea samples were equally determined by establishing equilibrium relative humidity (ERH) of 55, 65, 75, 85 and 95 % using a formulation of glycerol-water mixture at temperature of 30+-1 and the weight (loss or gain) of the samples was determined every 2 days. Irradiation at a dose of 0.25 kGy killed the C. maculatus within eight days and therefore 0.25 kGy would be economically beneficial as a control dose. There was significant difference (p is less than 0.05) in the percent mortality between the irradiated and the non-irradiated weevils, and the percent mortality increased with increase in the radiation dose. At moisture content of 14 % the irradiated cowpea samples were safely stored for one month at an equilibrium relative humidity of 60-75 % at a temperature of 29+-2 oC

Antibiotic-resistant staphylococci in South Africa one health approach

Thesis (PhD)--Stellenbosch University, 2024.ENGLISH ABSTRACT: Staphylococci cause a wide range of infections in humans and animals, with Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis and Staphylococcus haemolyticus the most common Staphylococcus species implicated in healthcare and community acquired infections. The emergence and dissemination of antibiotic resistance (ABR) among Staphylococcus species has complicated empiric treatment practices and limited treatment options, leading to increased mortality. The World Health Organization (WHO, 2015) declared antimicrobial resistance a threat to the treatment of infections. The “One Health” initiative addresses health care challenges holistically by including human health, animal health and environmental health to achieve better public health outcomes. This approach is being adopted by the WHO to mitigate the problem of ABR and research across these sectors is required. This study investigated ABR rates and described the molecular resistance mechanisms and population structures of staphylococci from community, clinical and farm settings. This was achieved by employing both traditional culture and phenotypic antibiotic susceptibility testing as well as whole genome sequencing. A systematic review was conducted to understand trends, strengths, and limitations in the area of ABR in staphylococci other than Staphylococcus aureus (SOSA) in animals. The findings suggested that there is high tetracycline and penicillin resistance among SOSA organisms in livestock and companion animals in Africa. The review also highlighted the lack of strain typing of SOSA in Africa and that research was more focused on cattle. To employ a One Health approach, this study therefore included pigs, which are common livestock in the Western Cape province of South Africa, stool samples from healthy children in the community, and clinical isolates. S. haemolyticus and S. epidermidis were identified in all three settings, and S. borealis was identified from the pigs and the healthy community-based children, the first report of this species in Africa. High rates of tetracycline resistance were observed amongst pigs and human contacts on the pig farms. The majority of the healthy community-based children were colonised by methicillin resistant SOSA, and in the clinical isolates high rates of multidrug resistance were observed. The distribution of tetracycline resistance suggests that pig farms might be a “hotspot” for tetracycline resistance which is then transferred via the community with moderate resistance rates, to clinical settings with lower rates of tetracycline resistance. The tetracycline resistance gene tetK was seen across all selected settings in SOSA, as was the erythromycin resistance gene, ermC. No common strain types were circulating across all selected settings. However, certain S. haemolyticus strain types were identified in community and clinical settings. Our ability to conclude on genetic relatedness in the selected settings was limited by inconsistent species distribution and sample size. The findings suggest that S. haemolyticus is predominant in the community and might be spreading into the clinical and farm settings while Mammaliicoccus sciuri is predominant in the farm setting with potential dissemination into the community. Although the number of Staphylococcus aureus from the study was small, SOSA were more resistant than S. aureus with diverse antibiotic resistance genes; evidence of SOSA as a reservoir of ABR genes.AFRIKAANSE OPSOMMING: Stafilokokke veroorsaak 'n wye reeks infeksies in mense en diere, met Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis en Staphylococcus haemolyticus die mees algemene Staphylococcus spesies wat betrokke is by gesondheidsorg en gemeenskapverworwe infeksies. Die opkoms en verspreiding van antibiotikaweerstandigheid (ABR) onder Staphylococcus spesies het empiriese behandelingspraktyke gekompliseer en behandelingsopsies beperk, wat lei tot verhoogde mortaliteit. Die Wêreldgesondheidsorganisasie (WHO, 2015) het antimikrobieseweerstand as 'n bedreiging vir die behandeling van infeksies verklaar. Die "One Health"-inisiatief spreek gesondheidsorguitdagings holisties aan deur menslike-, diere- en omgewingsgesondheid in te sluit om beter publieke gesondheidsuitkomste te bereik. Hierdie benadering word deur die WHO aangeneem om die probleem van ABR op te los en navorsing wat span oor hierdie sektore word vereis. Hierdie studie het ABR-patrone ondersoek en die molekulêre weerstandsmeganismes en populasiestrukture van stafilokokke uit gemeenskaps-, kliniese en plaasomgewings beskryf. Dit is bereik deur gebruik te maak van beide tradisionele kweek- en fenotipiese antibiotikavatbaarheidstoetse sowel as heelgenoomvolgordebepaling. 'n Sistematiese oorsig is uitgevoer om tendense, sterkpunte en beperkings op die gebied van ABR by Stafilokokke anders as Staphylococcus aureus (SOSA) by diere te verstaan. Die bevindinge het voorgestel dat daar hoë tetrasiklien- en penisillienweerstandigheid onder SOSA-organismes in vee en troeteldiere in Afrika is. Die oorsig het ook uitgelig dat daar ‘n gebrek aan stamtipering van SOSA in Afrika is en dat navorsing meer op beeste fokus. Om ‘n "One Health" benadering aan te neem het hierdie studie dus varke, wat algemene vee in die Wes-Kaap provinsie van Suid-Afrika is, stoelgangmonsters van gesonde kinders in die gemeenskap, sowel as kliniese isolate ingesluit. S. haemolyticus en S. epidermidis is in al drie omgewings iv https://scholar.sun.ac.za geïdentifiseer, en S. borealis is geïdentifiseer by varke en die gesonde gemeenskapsgebaseerde kinders, die eerste verslag van hierdie spesie in Afrika. Hoë vlakke van tetrasiklienweerstandigheid is onder varke en menslike kontakte op die varkplase waargeneem. Die meerderheid van die gesonde gemeenskapsgebaseerde kinders is deur metisillienweerstandige SOSA gekoloniseer, en in die kliniese isolate is hoë vlakke van multigeneesmiddelweerstandigheid waargeneem. Die verspreiding van tetrasiklienweerstandigheid dui daarop dat varkplase 'n brandpunt vir tetrasiklienweerstandigheid kan wees wat dan deur die gemeenskap met matige weerstandskoerse oorgedra word na kliniese omgewings met laer tetrasiklienweerstandigheidskoerse. Die tetrasiklienweerstandsgeen tetK is in SOSA in alle omgewings gevind, asook die eritromisienweerstandsgeen, ermC. Geen algemene stamtipes is in al die geselekteerde omgewings gevind nie. Sekere S. haemolyticus stamtipes is egter in gemeenskaps- en kliniese omgewings geïdentifiseer. Ons vermoë om afleidings te maak oor genetiese verwantskap in die geselekteerde omgewings is beperk deur oneweredige spesieverspreiding en monstergrootte. Die bevindinge dui daarop dat S. haemolyticus oorheersend in die gemeenskap is en moontlik na die kliniese en plaasomgewings kan versprei, terwyl Mammaliicoccus sciuri oorheersend in die plaasomgewing is met potensiële verspreiding na die gemeenskap. Alhoewel die aantal Staphylococcus aureus laag was, was SOSA meer weerstandig as S. aureus, met diverse ABR gene; ‘n bewys dat SOSA as reservoir van ABR-gene dien.Doctora

Dietary fatty acids alter mitochondrial phospholipid fatty acyl composition and proton leak in Drosophila melanogaster

Two groups of fruit flies (Drosophila melanogaster) were maintained on different diets. Mitochondria were isolated, proton leak was measured and phospholipid fatty acid composition determined. Mitochondria from flies fed on corn-base meal (containing high amounts of polyunsaturated fatty acids, 18:2(n-6) and 18:3(n-3) and low amounts of monounsaturated fattyacid, 18:1(n-9)) contained more polyunsaturated fatty acids in their membranes than mitochondria from flies fed on yeast-base meal (containing less amount of polyunsaturates and high amount of monounsaturates). The more polyunsaturated mitochondria were leakier toprotons than the more monounsaturated mitochondria

A Time Integration Method of Approximate Particular Solutions for Nonlinear Ordinary Differential Equations

We consider a time-dependent method which is coupled with the method of approximate particular solutions (MAPS) of Delta-shaped basis functions and the method of fundamental solutions (MFS) to solve nonlinear ordinary differential equations. Firstly, we convert a nonlinear problem into a sequence of time-dependent non-homogeneous boundary value problems through a fictitious time integration method. The superposition principle is applied to split the numerical solution at each time step into an approximate particular solution and a homogeneous solution. Delta-shaped basis functions are used to provide an approximation of the source function at each time step. The purpose of this is to allow a convenient derivation of an approximate particular solution. The corresponding homogeneous boundary value problem is solved using the method of fundamental solutions. Numerical results support the accuracy and validity of this computational method

Physical, chemical and microbiological changes in alcoholic fermentation of sugar syrup from cassava flour

Changes in alcoholic fermentation of sugar syrup produced from cassava flour with Saccharomyces cereviseae (baker’s yeast) were investigated. Cassava flour paste was hydrolysed using rice malt toproduce hydrolysate (sugar syrup), which was fermented at 28 – 30°C for 1, 2, 3, 4 and 5 days. The fermented sugar syrup was analysed for alcohol content, reducing sugars, specific gravity, soluble solids, pH, volatile acids and total acidity using standard analytical methods. Yeast growth was also monitored. Results showed that pH values decreased with increased total acidity with concomitant increase in yeast growth (biomass) and alcohol contents of the fermenting sugar syrup. There were decreases in soluble solid contents, refractive indices of the fermenting medium. Volatile acids (as acetic acids), increased with alcoholic fermentation. Fermentation of sugar syrup from cassava flour is associated with physical and chemical changes that occur in other form of fermentation alongside increased in biomass

Mitochondria as Pharmacological Targets: The Discovery of Novel Anti-Obesity Mitochondrial Uncouplers from Africa’s Medicinal Plants

Obesity results from prolonged positive imbalance between energy in take and expenditure. When food intake chronically exceeds the body’s energy need, an efficient metabolism results in the storage of the excess energy as fat. Mitochondria are the main centre for energy production in eukaryotic cells. Mitochondrial proton cycling is responsible for a significant proportion of basal or standard metabolic rate, therefore, further uncoupling of mitochondria may be a good way to increase energy expenditure and hence represent a good pharmacological target for the treatment of obesity. This implies that, any chemical agent or photochemical compound that further uncouples the mitochondria in vivo without having any effect on mitochondria activity could be a potential target in finding treatment for obesity. In the past, uncoupling by 2, 4-dinitrophenol has been used this way with notable success. This paper discusses the mitochondria as targets in the discovery of potential plant natural anti-obesity products from Africa’s rich rainforests.Key words: Uncoupling, Mitochondria, Pharmacology, Medicinal Plants, Obesity

Diamonds are forever:How myths can contribute to land degradation by small-scale diamond mining in Akwatia, Ghana

Conventional literature on land degradation has largely focused on factors such as logging, farming, mining and construction to explain the causes of this phenomenon, paying little attention to what motivates the decisions behind these factors particularly in poor countries. One of the factors that is least explored but promises to shed light on our understanding of and tackling land degradation is myth and how myths motivate decisions made on the exploitation of land resources that result in land degradation. Using qualitative approaches in the study of land degradation caused by small-scale mining operations in Akwatia, we found that the myth that diamonds regenerate and the soul of the dead bring forth diamonds largely contributes to re-mining of already mined sites and reclaimed pits leading to extensive land degradation. Scientific research into these myths and education of the small-scale miners are important in addressing land degradation.  Key words: Small-scale Mining, Diamonds, Land degradation, Myths, Ghan

Celebrity Endorsement and Consumer Buying Behaviour:Enhancing the Promotion Function of Marketing in the Central Business Area of Accra, Ghana

This paper examines the phenomena of celebrity endorsement in advertising as part of marketing promotions. The concept is considered as a measure of positively influencing consumers'  behaviour towards making a purchase of a company's offer. The major considerations in this paper were to unravel the factors or variables considered in selecting a celebrity or making a purchase; the extent to which a celebrity's endorsement influences consumers' purchase or re-buy behaviour; as well as its influence generally on marketing promotions. The reviewed literature and the data captured from about a hundred and forty-eight respondents covering management, internal customers and external customers gives the findings a high level of validity and reliability. The results indicates that company's select celebrities based on credibility, brand match and attractiveness whiles consumers' are influenced by price, celebrity endorsement, quality and packaging. There was overwhelming agreement for a greater extent of influence on behaviour as well as marketing promotions. The paper concluded on the positive relationships celebrity endorsement has with consumer behaviour and marketing promotions in general. It recommended that companies using celebrities should ensure that the celebrities match the brand, that is, the celebrity must have the value and image required to advertise the brand. It is only when adverts are matched up by attractiveness and expertise that the brand attitude would be more favourable, and find greater purchase intentions. We study shall replicate this study in Togo and Nigeria to gauge the regional view of the influences of celebrity endorsement on consumers' purchase behaviour. Key Words: Celebrity Endorsement, Consumer Behaviour, Marketing Promotions

Beware Zombies and Unicorns: Toward critical patient and public involvement in health research in a neoliberal context

Patient and Public Involvement (PPI) in UK National Health Service (NHS) research has become an imperative in policy and practice. However, lack of clarity on what PPI is (or might be) has given rise to a poorly monitored, complex field of activity, variously framed by the expectations of policy makers, funders, host organisations, researchers, health professionals, individual recruits, volunteers, activists and third sector organisations. The normative shift towards PPI has taken place within a neoliberal policy context, the implications of which needs to be explicitly considered, particularly after the Brexit referendum which has left policy makers and researchers wondering how to better appeal to a distrustful public subjected to ‘post-truth’ and ‘dog whistle’ politics. This commentary examines the prospects for a more critical approach to PPI which addresses context, is evidence-informed and mindful of persistent inequalities in health outcomes, at a time when models of PPI in NHS health research tend to be conceptually vague, derived from limited clinical and managerial settings, and centred on a construction of the abstract, rational, compliant and self-managing patient or lay-person