Antimicrobial resistance results in increased morbidity and mortality, and increased health-care costs. Therefore the need to develop new classes of antibiotics is indispensable. Antimicrobial peptides are a relatively new class of potential antibiotics which are fast acting, possess broad-spectrum activity and are able to escape many of the currently known mechanisms of drug resistance. They have been shown to be active against Gram-negative and Gram-positive bacteria, fungi, enveloped viruses and even cancer cells. However, toxicity to healthy host cells remains a concern and has affected the clinical development of therapeutics based on antimicrobial peptides. The purpose of this review is to discuss recent advances in research focused on antimicrobial peptides from frogs and the challenges in conducting research in this area in southern Africa. An extensive literature review of relevant articles published between 1980 and the present was conducted using PubMed, ScienceDirect, Sabinet, Elsevier and GoogleScholar. There has been little research done on anurans from southern Africa which are endemic to the region, and there is therefore a need to focus on this group for the purposes of bioprospecting for potentially new antimicrobial peptide compounds.

http://www.sajs.co.za/index.php/SAJS/article/view/795

Overweight and obesity in children and adolescents are on the increase worldwide.Overweight and obesity increase the risk for the development of non-communicable diseases during childhood and adolescence, and predispose the individual to the development of overweight, obesity, cardiovascular disease, and metabolic and other disorders in adulthood. In Africa the number of overweight or obese children has doubled since 1990. In South Africa, overweight and obesity in children and adolescents are on the increase, but the prevalence varies with age, gender and population group. These differences are important when intervention programmes and policies are considered. South Africa faces a double burden of disease where undernutrition and overweight or obesity are found in the same populations, in the same households and even in the same children. Malnutrition is a major contributor to the double burden of disease in South African children and adolescents.

http://www.sajs.co.za/index.php/SAJS/article/view/907

Powdery scab, a root and tuber disease caused by the pathogen Spongospora subterranea f.sp. subterranea (Sss), poses a major problem to potato producers worldwide because it affects potato quality. Inoculum can be seed-borne or originate from contaminated growing media or contaminated equipment. During 2006, a potato mini-tuber production facility in Ceres in the Western Cape Province of South Africa had an outbreak of powdery scab. The purpose of this study was to detect Sss in the production facility and identify the source or sources of contamination so that corrective measures could be taken to eradicate the pathogen. Swab samples were taken from numerous points in the facility in 2009 and Sss-specific primers (Sps1 and Sps2) were used in a polymerase chain reaction to detect Sss. Of 11 surfaces tested, 6 were positive for Sss. A second set of swab samples was taken after efforts were made to eradicate the pathogen through improved facility hygiene measures to determine whether these corrective measures were efficient. Corrective measures resulted in a disease-free harvest from 2009 onwards. This novel study has value for the mini-tuber industry as production tunnels can be tested for the presence of Sss and other pathogens before planting to ensure that, where suitable control measures are available, disease-free mini-tubers are produced.

http://www.sajs.co.za/index.php/SAJS/article/view/614

Urban population increase has caused significant urban landscape transrmation globally. Bere 1994, South Africa’s highly regulated urban growth was shaped by the restrictive Prevention of Illegal Squatters Act of 1951. After the abolishment of the act in the 1980s, the period of transition to democracy in the 1990s was characterised by an unprecedented urban population influx that caused a myriad of socio-economic and environmental challenges. These challenges have consequently compounded the need to monitor urban growth r the planning and optimisation of urban spaces. The limitations of traditional mapping methods, such as surveying and photogrammetry, in urban mapping are well documented. In the recent past, satellite remote sensing has emerged as one of the most viable urban mapping tools. Using post-classification comparisons, we sought to monitor major land use and land cover (LULC) changes in the city of Port Elizabeth during South Africa’s democratic transition (1990–2000). Images r 1990, 1995 and 2000 were acquired, geo-rectified and atmospherically corrected. An iterative self-organising data analysis (ISODATA) was then used to generate existing LULCs. Classes generated using ISODATA were then amalgamated to the city’s major LULCs and resultant classes were validated using aerial photographs and field visits. Results showed that ‘Built-up’ and ‘Bare surface’ LULC classes had the highest increase and decrease, respectively. There was no change in the ‘Beach or dune’ LULC, whereas ‘Green vegetation’ and ‘Water’ classes had minimal changes. This study illustrates the efficacy of remote sensing in monitoring urban change and the potential of remote sensing to aid decision-making in rapidly changing urban landscapes.

http://www.sajs.co.za/index.php/SAJS/article/view/886

We considered the impact of external influences on a GPS receiver and how these influences affect the capabilities of civilian-type GPS receivers. A standard commercial radio frequency signal generator and passive GPS antenna were used to test the sensitivity of GPS to intentional jamming; the possible effects of the terrain on the propagation of the jamming signal were also tested. It was found that the high sensitivity of GPS receivers and the low strength level of GPS satellite signals combine to make GPS receivers very vulnerable to intentional jamming or unintentional radio frequency interference. Terrain undulation was used to shield GPS antennas from the direct line-of-sight of the jamming antenna and this indicated that terrain characteristics can be used to mitigate the effects of jamming. These results illuminate the vulnerability of civilian-type GPS receivers to the possibility and the ease of disablement and establish the foundation for future work.

http://www.sajs.co.za/index.php/SAJS/article/view/749

Having spent some 50 years as an organic chemist with an interest in medicinal plant chemistry in South Africa it was relevant now to ask three questions, (1) when were natural products first utilised, (2) who were the people involved, and (3) what is the status quo? Based on older literature published in the South African Journal of Chemistry, information gleaned from attendance at innumerable chemistry conferences, and relevant literature in university archives, a great deal of information was gathered to answer the first two questions. For example, that the first veterinarian to treat cattle diseases caused by poisonous plants in the Eastern Cape was Dr Jotella Soga in the 1890s. Contributions from other prominent scientists such as Marais, Rindl, Rimington and Warren followed. From about 1940 to the 1990s, researchers concentrated mainly on the isolation of new compounds from local plants for which some indigenous knowledge was recorded. Foreign chemists also arrived and did a fair amount of ‘exploitation’ of natural products. Thus, the anti-cancer compound combretastatin was first isolated from the indigenous tree Combretum caffrum. Plant chemistry in South Africa has blossomed in the last decade, with many students from previously disadvantaged backgrounds, but with a keen interest in muti or medicinal chemistry, entering the field. Recent findings have rekindled the belief that a major development in natural products would at last emerge from Africa.

http://www.sajs.co.za/index.php/SAJS/article/view/765

We investigated proportionalities in the enterprise structures of 125 South African towns through examining four hypotheses, (1) the magnitude of enterprise development in a town is a function of the population size of the town; (2) the size of an enterprise assemblage of a town is a function of the town’s age; (3) there are statistically significant relationships, and hence proportionalities, between the total number of enterprises in towns and some, if not all, of the enterprise numbers of different business sectors in towns; and (4) the implications of proportionalities have far-reaching implications for rural development and job creation. All hypotheses were accepted on the basis of statistically significant (p < 0.05) correlations, except for the second hypothesis – the age of a town does not determine the size of its enterprise assemblage. Analysis for the fourth hypothesis suggested that there are two broad entrepreneurial types in South African towns: ‘run-of-the-mill’ entrepreneurs and ‘special’ entrepreneurs, which give rise to different enterprise development dynamics. ‘Run-of-the- mill’ enterprises are dependent on, and limited by, local demand and if there is only a small demand, the entrepreneurial space is small. By comparison, ‘special’ enterprises have much larger markets because their products and/or services are exportable. We propose that the fostering of ‘special’ entrepreneurs is an imperative for local economic development in South African towns.

http://www.sajs.co.za/index.php/SAJS/article/view/588