An experimental study of human melanoma cells cutured in vitro

This thesis records the results of a series of experiments that were designed to examine the biology of human malignant melanoma cells cultured in vitro. The studies were so planned as to document phenotypic differences that exist between melanomas, to define respects in which melanoma cell differentiation could be modulated and to correlate biochemical variability with in vivo behaviour as measured in the nude mouse. Melanoma cell lines were established from biopsy material obtained from 7 patients at Groote Schuur Hospital. Two of these lines synthesized tyrosinase and melanin at a rate that was directly related to cell density. The five remaining lines did not pigment. ii All of the lines showed aneuploidy; 5 of the 7 showed anchorageindependent growth; and 6 of the 7 grew as lethal tumours in nude mice. As has been found with all other melanomas studied, these cells released a plasminogen activator that was chemically and immunologically identical to tissue activator. One of the lines proved to be an exception to this general rule in that it synthesized urokinase-type enzyme. Unlike most other human cells cultured in vitro, melanoma cells proved to be relatively refractory to hormonal stimuli. Addition of estrogen, progesterone, testosterone, dexamethasone or melanocyte-stimulating hormone to the culture medium had very little effect on cellular release of plasminogen activator, upon cell growth, or upon cellular morphology. Although remarkably resistant to hormonal influences, cellular release of plasminogen activator did appear to be inhibited to a striking degree by cocultivation with normal skin fibroblasts. This observation led to the discovery of a phenomenon in which fibroblasts of many types bound tissue-type plasminogen activator and so removed it from the medium. This was accompanied by an apparent change in molecular weight of the melanoma cell enzyme from 72K daltons to approximately 115K daltons, suggesting the presence of a 40-SOK binding molecule. iii In an attempt to influence in vitro differentiation, the tumour promoter tetradecanoylphorbol acetate, and the differentiation-inducing retinoid, retinoic acid, were added to the two pigmenting cell lines. The effects of these compounds on induction of tyrosinase activity, morphological change or plasminogen activator release differed. In the one cell line, tetradecanoylphorbol acetate caused morphological maturation with a decrease in the rate of plasminogen activator release and no obvious effect upon pigmentation. This line was relatively resistant to the action of retinoids. The other pigmenting line responded hardly at all to the tumour promoter. Retinoic acid, on the other hand, inhibited the induction of tyrosinase activity, yet caused an inhibition of growth and plasminogen activator release. A number of interesting observations could be made in experiments in which melanoma cells were inoculated into nude mice. Firstly, the growth rate of the tumours ~n vivo correlated poorly with the doubling times of the corresponding cells cultured in vitro. Secondly, despite a marked inhibitory effect of fibroblasts on plasminogen activator in vitro, coinjection of fibroblasts and melanoma cells in vivo greatly enhanced tumour growth when small tumour cell inocula were used and shortened the latent period for tumour appearance with larger inocula. Thirdly, melanomas growing in nude mice differed strikingly in their ability to elicit a desmoplastic response. Tumours in which large amounts of host connective tissue were deposited tended to be heavily contaminated with murine fibroblasts when re-established in vitro. This contamination was not seen with tumours that contained very little connective tissue. These results point to the existence of a melanoma-associated fibrogenic factor. Finally, by excision of the primary tumour, it was possible to avoid death of the animal from local complications and so allow time for metastases to develop. In three mice, metastatic melanoma deposits could be detected by this device, so establishing a protocol for the use of nude mice as valid models for the experimental study of metastatic spread of human tumours

Unlocking Potential: Economic Development Options for Coney Island

The Coney Island neighborhood fares worse than average in a number of key indicators of resident outcomes, health, finances, and community support. The site of the Abe Stark ice rink provides an opportunity to address these issues and jumpstart the local economy. The story of the Coney Island neighborhood and its residents has been explored through historical sources and data on current conditions. Through zoning analysis, some development options have been proposed. These options are put through economic impact analysis and financial viability analysis to ensure positive economic benefit and large-scale financial viability. A formal recommendation to develop the current Abe Stark site into a medium density mixed used development which financially supports a large-scale recreation development has been detailed

Proterozoic crustal evolution of the Awasib Mountain terrain, southern Namibia, with speical reference to the volcanic Haiber flats formation

Bibliography: pages 245-257.The middle to late Proterozoic Awasib Mountain terrain (AMT) straddles the boundary between the Rehoboth and Gordonia subprovinces in southern Namibia. The AMT is made up of two major crustal components, the older of which is correlated with the Namaqualand Metamorphic Complex (NMC), and the younger with the Sinclair Sequence

Factors influencing peak expiratory flow in teenage boys

Background. Peak expiratory flow (PEF) is a useful measure of pulmonary health status and is frequently utilised in asthm, management. Reduction in PEF is usually indicative of OIlS( of asthma symptoms. However, use can be made of PEF values only if normal values are known. The definition of normal range is always difficult and may vary between regions and be affected by a variety of factors.Objective. To establish PEF values for teenage boys in a Cape Town suburb and examine factors that possibly influence this measurement.Setting. A high school for boys in the southern suburbs of Cape Town.Methods. Measurements of PEF were taken for 124 boys. Subjects were approximately 16 years old and apparently healthy at the time of survey. Further details were provid by means of a questionnaire.Results. PEF ranged from 350 to 760 1/min, with a mean (± standard deviation (SD» of 539 ± 681/min. Factors expected to influence PEF included height and mass, where is unexpected factors included sport intensity and academic grade. A trend to reduced peak flow was already evident in boys who smoked and boys from homes where a parent smoked. Regression analysis suggested peak flow differenct.s in our population compared with the standard reference.Conclusion. Interpretation of results obtained from peak-flow instruments should take into account additional knowledge concerning the individual. Further surveys of the South African population and of different groups should be done to establish local standards and factors influencing PE

The critical needs and challenges for genetic architecture studies in Africa

Human genetic studies have long been vastly Eurocentric, raising a key question about the generalizability of these study findings to other populations. Because humans originated in Africa, these populations retain more genetic diversity, and yet individuals of African descent have been tremendously underrepresented in genetic studies. The diversity in Africa affords ample opportunities to improve fine-mapping resolution for associated loci, discover novel genetic associations with phenotypes, build more generalizable genetic risk prediction models, and better understand the genetic architecture of complex traits and diseases subject to varying environmental pressures. Thus, it is both ethically and scientifically imperative that geneticists globally surmount challenges that have limited progress in African genetic studies to date. Additionally, African investigators need to be meaningfully included, as greater inclusivity and enhanced research capacity afford enormous opportunities to accelerate genomic discoveries that translate more effectively to all populations. We review the advantages, challenges, and examples of genetic architecture studies of complex traits and diseases in Africa. For example, with greater genetic diversity comes greater ancestral heterogeneity; this higher level of understudied diversity can yield novel genetic findings, but some methods that assume homogeneous population structure and work well in European populations may work less well in the presence of greater heterogeneity in African populations. Consequently, we advocate for methodological development that will accelerate studies important for all populations, especially those currently underrepresented in genetics.Peer reviewe

Putting RFMix and ADMIXTURE to the test in a complex admixed population

CITATION: Uren, C., Hoal, E. G. & Moller, M. 2020. Putting RFMix and ADMIXTURE to the test in a complex admixed population. BMC Genetics, 21:40, doi:10.1186/s12863-020-00845-3.The original publication is available at https://bmcinfectdis.biomedcentral.comPublication of this article was funded by the Stellenbosch University Open Access FundBackground: Global and local ancestry inference in admixed human populations can be performed using computational tools implementing distinct algorithms. The development and resulting accuracy of these tools has been tested largely on populations with relatively straightforward admixture histories but little is known about how well they perform in more complex admixture scenarios. Results: Using simulations, we show that RFMix outperforms ADMIXTURE in determining global ancestry proportions even in a complex 5-way admixed population, in addition to assigning local ancestry with an accuracy of 89%. The ability of RFMix to determine global and local ancestry to a high degree of accuracy, particularly in admixed populations provides the opportunity for more accurate association analyses. Conclusion: This study highlights the utility of the extension of computational tools to become more compatible to genetically structured populations, as well as the need to expand the sampling of diverse world-wide populations. This is particularly noteworthy as modern-day societies are becoming increasingly genetically complex and some genetic tools and commonly used ancestral populations are less appropriate. Based on these caveats and the results presented here, we suggest that RFMix be used for both global and local ancestry estimation in worldwide complex admixture scenarios particularly when including these estimates in association studies.https://bmcgenet.biomedcentral.com/articles/10.1186/s12863-020-00845-3Publisher's versio

Genetic resistance to Mycobacterium Tuberculosis infection and disease

CITATION: Möller, M. et al. 2018. Genetic resistance to Mycobacterium tuberculosis infection and disease. Frontier in Immunology, 9:2219, 1-13. doi:10.3389/fimmu.2018.02219.The original publication is available from https://www.frontiersin.org/journals/immunology#Natural history studies of tuberculosis (TB) have revealed a spectrum of clinical outcomes after exposure to Mycobacterium tuberculosis, the cause of TB. Not all individuals exposed to the bacteriumwill become diseased and depending on the infection pressure, many will remain infection-free. Intriguingly, complete resistance to infection is observed in some individuals (termed resisters) after intense, continuing M. tuberculosis exposure. After successful infection, the majority of individuals will develop latent TB infection (LTBI). This infection state is currently (and perhaps imperfectly) defined by the presence of a positive tuberculin skin test (TST) and/or interferon gamma release assay (IGRA), but no detectable clinical disease symptoms. The majority of healthy individuals with LTBI are resistant to clinical TB, indicating that infection is remarkably well-contained in these non-progressors. The remaining 5–15% of LTBI positive individuals will progress to active TB. Epidemiological investigations have indicated that the host genetic component contributes to these infection and disease phenotypes, influencing both susceptibility and resistance. Elucidating these genetic correlates is therefore a priority as it may translate to new interventions to prevent, diagnose or treat TB. The most successful approaches in resistance/susceptibility investigation have focused on specific infection and disease phenotypes and the resister phenotype may hold the key to the discovery of actionable genetic variants in TB infection and disease. This review will not only discuss lessons from epidemiological studies, but will also focus on the contribution of epidemiology and functional genetics to human genetic resistance to M. tuberculosis infection and disease.https://www.frontiersin.org/articles/10.3389/fimmu.2018.02219/fullhttps://doi.org/10.3389/fimmu.2018.02219Published review articlePublishers versio