Browsing by Author "Engelbrecht, L."

Now showing 1 - 6 of 6
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    Anti-inflammatory cellular targets on neutrophils elucidated using a novel cell migration model and confocal microscopy : a clinical supplementation study
    (BioMed Central, 2018-01-05) Smith, T.; Engelbrecht, L.; Smith, C.
    Background In vivo studies have shown grape seed-derived polyphenols (GSP) to benefit in recovery from muscle injury by modulation of neutrophil infiltration into damaged tissue, thereby reducing secondary damage, as well as by facilitating an early anti-inflammatory macrophage phenotype shift. The current study aimed to provide data in this context from human models and to elucidate specific molecular targets of GSP. Using a placebo-controlled, double-blind study design, eighteen normally healthy volunteers between the ages of 18–35 years old (13 female and 5 male) were orally supplemented with 140 mg/day of GSP for 2 weeks. Blood samples (days 0 and 14) were comprehensively analysed for in vitro neutrophil chemokinetic capacity towards a chemotaxin (fMLP) using a novel neutrophil migration assay, in combination with live cell tracking, as well as immunostaining for neutrophil polarisation factors (ROCK, PI3K) at migration endpoint. Macrophage phenotype marker expression was assessed using flow cytometry. Results fMLP induced significant chemokinesis (P < 0.01), validating our model. GSP did not exert a significant effect on neutrophil chemokinesis in this non-compromised population, but tended to decrease overall ROCK expression in fMLP-stimulated neutrophils (P = 0.06). Macrophage phenotype markers CD274 and MPO – indicators of a pro-inflammatory M1 phenotype – seemed to be normalised relative to baseline expression levels after GSP treatment. Conclusions Current data suggest that GSP may have a modulatory effect on the ROCK-PI3K-PTEN system, but results in this normal population is not conclusive and should be confirmed in a larger, more inflamed population. Potential modulation of macrophage phenotype by GSP should be investigated further.
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    A decision support model for passenger capacity design of BRT stations
    (Southern African Institute for Industrial Engineering, 2012) Engelbrecht, L.; Bekker, J.
    ENGLISH ABSTRACT: In this paper, a decision support model for capacity planning of bus rapid transit stations is proposed. Static, deterministic models are used at present for station capacity design, whereas bus passenger flow through stations is dynamic with an associated stochastic element. Passenger arrivals vary over time, and are driven by bus schedules and process variation. The proposed model produces capacity design curves for given input data sets and bus schedules, and assists the station designer without being prescriptive. A case study of model application to the proposed Thibault Station in Cape Town, South Africa, is presented.
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    Malolactic fermentation : the ABC's of MLF
    (SASEV, 2010-09) Lerm, E.; Engelbrecht, L.; Du Toit, M.
    There are two main fermentations associated with the winemaking process. Alcoholic fermentation is conducted by the yeast culture and malolactic fermentation takes place as a result of the metabolic activity of lactic acid bacteria, specifically from the genera Oenococcus, Lactobacillus, Pediococcus and Leuconostoc. Malolactic fermentation is dened as the conversion of malic acid to lactic acid and CO2 and besides deacidification also contributes to microbial stability and modification of the aroma prole. This paper aims to provide a comprehensive review discussing all the main aspects and factors related to malolactic fermentation, including practical considerations for monitoring and ensuring a successful fermentation.
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    Selection and characterisation of oenococcus oeni and lactobacillus plantarum South African wine isolates for use as malolactic fermentation starter cultures
    (South African Journal for Enology and Viticulture, 2011) Lerm, E.; Engelbrecht, L.; Du Toit, M.
    This study focused on characterising 23 Oenococcus oeni and 19 Lactobacillus plantarum strains isolated from the South African wine environment for the development of potential commercial malolactic fermentation (MLF) starter cultures. These strains were characterised with regards to oenological important characteristics, including the genetic screening for enzyme-encoding genes (enzymes that are involved/implicated in wine aroma modification, as well as enzymes pertaining to the wholesomeness of the final wine product), their fermentation capabilities, the ability to maintain viability during MLF, as well as the volatile acidity production. A total of three O. oeni and three L. plantarum strains were selected at the completion of this study. These six strains showed the most potential during the characterisation stages of the study and were able to successfully complete MLF in Pinotage wine. It was also found that L. plantarum strains displayed a more diverse enzyme profile than O. oeni strains, particularly with regards to the presence of the aroma-modifying enzymes β-glucosidase and phenolic acid decarboxylase (PAD), which implies the future use of this species in the modification of the wine aroma profile and use as commercial starter culture.
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    Selection and characterisation of Oenococcus oeni and Lactobacillus plantarum South African wine isolates for use as malolactic fermentation starter cultures
    (South African Society for Enology and Viticulture, 2011) Lerm, E.; Engelbrecht, L.; Du Toit, M.
    This study focused on characterising 23 Oenococcus oeni and 19 Lactobacillus plantarum strains isolated from the South African wine environment for the development of potential commercial malolactic fermentation (MLF) starter cultures. These strains were characterised with regards to oenological important characteristics, including the genetic screening for enzyme-encoding genes (enzymes that are involved/implicated in wine aroma modification, as well as enzymes pertaining to the wholesomeness of the final wine product), their fermentation capabilities, the ability to maintain viability during MLF, as well as the volatile acidity production. A total of three O. oeni and three L. plantarum strains were selected at the completion of this study. These six strains showed the most potential during the characterisation stages of the study and were able to successfully complete MLF in Pinotage wine. It was also found that L. plantarum strains displayed a more diverse enzyme profile than O. oeni strains, particularly with regards to the presence of the aroma-modifying enzymes β-glucosidase and phenolic acid decarboxylase (PAD), which implies the future use of this species in the modification of the wine aroma profile and use as commercial starter culture.
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    A strategic model of macro-economic and supply chain factors that influence the decision-making process of SA retailers when expanding their footprint in African countries
    (Southern African Institute for Industrial Engineering, 2018) Engelbrecht, L.; Van Rensburg, A. C. J.
    ENGLISH ABSTRACT: As part of the era of globalisation, the foreign market expansion of retailers is a trend that draws the attention of economists and researchers alike, and is an ever-expanding field of scholarly review. Africa is no exception to the process of globalisation, and as the local South African retail market becomes saturated with increasing levels of competition, large retailers are gradually experiencing more pressure to expand their footprint into other African countries. Foreign market expansion is a business decision that requires a structured analytical framework to assist in the decision-making efforts of potential foreign investors. Models can be synthesised to assess and prioritise which market, country, or region to enter next; what the opportunities and risk of such a move will be; and what the business case would look like in terms of cost and benefit. Only a limited amount of literature discusses this topic in the specific context of South African retailers, creating an opportunity for further research. This paper presents a strategic decision-support model to assist South African retailers in making well-informed decisions about which sub-Saharan African market to enter next. A holistic approach is taken that covers various disciplines, including supply chain management, economics of development, and financial management.