Stephen Meddows-Taylor

Prof. Stephen Meddows-Taylor

Department of Life and Consumer Sciences, University of South Africa, Pretoria, Gauteng, South Africa
orcid

Research Focus & Metrics

Academic Career Length

29Years (1998-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2018 in Food Research International
Verified
Journal Article
Open access
SRShonisani Eugenia Ramashia
Shonisani Eugenia Ramashia
EGE.T. Gwata
E.T. Gwata
SMStephen Meddows-Taylor
Stephen Meddows-Taylor
TATonna Anyasi
Tonna Anyasi
AJA.I.O. Jideani
A.I.O. Jideani
The study determined the physical properties of finger millet (FM) (Eluesine coracana) grains and the functional properties of FM flour. Physical properties such as colour attributes, sample weight, bulk density, true density, porosity, surface area, sample volume, aspect ratio, sphericity, dimensional properties and moisture content of grain cultivars were determined. Water absorption capacity (WAC), bulk density (BD), dispersibility, viscosity and micro-structure of FM flours were also evaluated. Data collected were analyzed using SPSS statistical software version 23.0. Results showed that milky cream cultivar was significantly higher (p<0.05) than other samples in sample weight, bulk density, true density, aspect ratio and sphericity. However, pearl millet, used as a control, was significantly different from FM flour on all dimensional properties. Moisture content of milky cream showed higher significant difference for both grains and flours as compared to brown and black grain/flours. Milky cream cultivar was significantly different in L*, b*, C*, H* values, WAC, BD and dispersibility for both FM grains and flours. Data showed that brown flour was significantly higher in viscosity than in milky and black flours. Microstructure results revealed that starch granules of raw FM flours had oval/spherical and smooth surface. The study is important for agricultural and food engineers, designers, scientists and processors in the design of equipment for FM grain processing. Results are likely to be useful in assessing the quality of grains used to fortify FM flour.

1 February 2019 in Science of The Total Environment
Verified
Journal Article
Closed access
Timothy SibandaTimothy Sibanda
Timothy Sibanda
Ramganesh SelvarajanRamganesh Selvarajan
Ramganesh Selvarajan
TMTitus Msagati
Titus Msagati
SVSiddarthan Venkatachalam
Siddarthan Venkatachalam
SMStephen Meddows-Taylor
Stephen Meddows-Taylor

15 January 2002 in Clinical Infectious Diseases
Verified
Journal Article
Open access
PDF file
LKLouise Kuhn
Louise Kuhn
SMStephen Meddows-Taylor
Stephen Meddows-Taylor
GGGlenda Gray
Glenda Gray
CTCaroline Tiemessen
Caroline Tiemessen
Significant immunological changes are associated with intrauterine human immunodeficiency virus (HIV) encounter among uninfected infants of HIV-infected mothers. Peripheral blood cells of more than one-third of these exposed-uninfected infants proliferate and produce IL-2 after stimulation with HIV, and HIV-specific CD4+ T helper cell responses can be quantified in nearly all when sensitive intracellular cytokine assays are used. HIV-specific CD8+ cytotoxic T lymphocyte responses can be elicited in some, although less frequently. It is difficult to demonstrate that these responses are components of protective immunity and not simply epiphenomena of exposure. However, HIV-specific responses are associated with lack of infection, even with prolonged reexposure through breast-feeding. Elevations in nonspecific markers of immune activation provide further corroboration, as do similar findings in adults, consistent across all known routes of HIV transmission. Many questions remain, but much can be learned from this special population that may be informative for development of effective immunity in response to HIV vaccines.

20 April 2017 in Molecules
Verified
Journal Article
Open access
PDF file
Ramganesh SelvarajanRamganesh Selvarajan
Ramganesh Selvarajan
Timothy SibandaTimothy Sibanda
Timothy Sibanda
Memory TekereMemory Tekere
Memory Tekere
HNHLENGILIZWE NYONI
HLENGILIZWE NYONI
SMStephen Meddows-Taylor
Stephen Meddows-Taylor
Though intensive research has been channeled towards the biotechnological applications of halophiles and other extremophilic microbes, these studies have not been, by any means, exhaustive. Saline environments still offer a vast diversity of microbes with potential to produce an array of natural products which can only be unlocked by concerted research efforts. In this study, a combination of culture and molecular approaches were employed to characterize halophilic bacteria from saltpan water samples and profile their potential biotechnological applications. Physicochemical analysis of the water samples showed that pH was alkaline (pH 8.8), with a salinity of 12.8%. 16S rRNA gene targeted amplicon analysis produced 10 bacterial phyla constituting of Bacteroidetes (30.57%), Proteobacteria (15.27%), Actinobacteria (9.05%), Planctomycetes (5.52%) and Cyanobacteria (3.18%). Eighteen strains were identified using sequencing analysis of the culturable bacterial strains. From these, the strains SP7 and SP9 were positive for cellulase production while the strains SP4, SP8 and SP22 were positive for lipase production. Quantitative enzyme assays showed moderate extracellular cellulase activity (1.95 U/mL) and lipase activity (3.71 U/mL) by the isolate SP9 and SP4 respectively. Further, of the six isolates, the isolate SP9 exhibited exploitable potential in the bioremediation of hydrocarbon pollution as demonstrated by its fairly high activity against benzanthracene (70% DCPIP reduction). Elucidation of the isolates secondary metabolites showed the production of the molecules 2,3-butanediol, hexahydro-3-(2-methylpropyl)pyrrole[1,2a]pyrazine-1,4-dione, aziridine, dimethylamine and ethyl acetate (GC-MS) and oxypurinol and 5-hydroxydecanoic acid (LC-MS), particularly by the isolate Salinivibrio sp. SP9. Overall, the study showed that the isolated halophiles can produce secondary metabolites with potential industrial and pharmaceutical application.

1 February 2006 in Clinical and Vaccine Immunology
Verified
Journal Article
Open access
PDF file
ARAnnelies Van Rie
Annelies Van Rie
SMShabir A. Madhi
Shabir A. Madhi
JHJayvant R. Heera
Jayvant R. Heera
SMStephen Meddows-Taylor
Stephen Meddows-Taylor
AWAaron M. Wendelboe
Aaron M. Wendelboe
CTCaroline Tiemessen
Caroline Tiemessen
In utero sensitization to infectious pathogens can establish immunological memory and may influence the immune response to unrelated antigens. Little is known about the influence of intrauterine human immunodeficiency virus (HIV) exposure on the cellular immune response to mycobacterial antigens. Whole-blood culture gamma interferon (IFN-γ) production in response to mycobacterial antigens was measured at birth and 6 weeks of age to determine the characteristics of the IFN-γ response in HIV-exposed infants toMycobacterium bovisBCG and mycobacterial antigens. At birth, we observed an increased immune activation in response to phytohemagglutinin among HIV-exposed, uninfected infants. In a proportion of these infants, we also observed an increased immune activation in response to purified protein derivative, BCG, and early secreted antigen target 6. Increases in the IFN-γ response to the four antigens between birth and 6 weeks of age, observed in all HIV-unexposed infants, was absent in a substantial proportion of HIV-exposed, uninfected infants. The immunological differences persisted at 6 weeks of age, suggesting a sustained impact of in utero immune priming by HIV. Intrauterine exposure to HIV affects the infants' cellular immune response to mycobacterial antigens, either specifically or as a consequence of nonspecific, broadly reactive immune activation. Further studies will be important to help determine optimal vaccination and disease prevention strategies for this vulnerable population group.

20 August 2007 in AIDS
Verified
Journal Article
Closed access
LKLouise Kuhn
Louise Kuhn
DSDiana B Schramm
Diana B Schramm
SDSamantha Donninger
Samantha Donninger
SMStephen Meddows-Taylor
Stephen Meddows-Taylor
ACAshraf H Coovadia
Ashraf H Coovadia
CTCaroline Tiemessen
Caroline Tiemessen
Background: Individuals with more copies of CCL3L1 (CCR5 ligand) than their population median have been found to be less susceptible to HIV infection. We investigated whether maternal or infant CCL3L1 gene copy numbers are associated with perinatal HIV transmission when single-dose nevirapine is given for prevention. Method: A nested case–control study was undertaken combining data from four cohorts including 849 HIV-infected mothers and their infants followed prospectively in Johannesburg, South Africa. Access to antiretroviral drugs for the prevention of perinatal transmission differed across the cohorts. Maternal and infant CCL3L1 gene copy numbers per diploid genome (pdg) were determined by real-time polymerase chain reaction for 79 out of 83 transmitting pairs (∼10% transmission rate) and 235 randomly selected non-transmitting pairs. Results: Higher numbers of infant, but not maternal, CCL3L1 gene copies were associated with reduced HIV transmission (P = 0.004) overall, but the association was attenuated if mothers took single-dose nevirapine or if the maternal viral load was low. Maternal nevirapine was also associated with reduced spontaneously released CCL3 (P = 0.007) and phytohemagglutinin-stimulated CCL3 (P = 0.005) production in cord blood mononuclear cells from uninfected infants. Conclusion: We observed a strong association between higher infant CCL3L1 gene copies and reduced susceptibility to HIV in the absence of maternal nevirapine. We also observed a reduction in newborn CCL3 production with nevirapine exposure. Taken together, we hypothesize that nevirapine may have direct or indirect effects that partly modify the role of the CCR5 ligand CCL3 in HIV transmission, obscuring the relationship between this genetic marker and perinatal HIV transmission.