Publications by authors named "Stephen Meddows-Taylor"

This work investigated the antifungal, cytotoxic and LPS-induced anti-inflammatory effects of five species (, , and ). The antifungal activity of the aqueous-methanolic extracts were performed using the broth dilution method against four non-albicans species (, and ). The cytotoxic and anti-inflammatory effects of the extracts were evaluated on African green monkey Vero kidney cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay and the 2',7'-dichlorofluorescin diacetate (HDCF-DA) method.

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The genus , previously known as Acacia, belongs to the family Fabaceae, subfamily Leguminosae, which are flowering plants, commonly known as thorn trees. They are traditionally used medicinally in various countries including South Africa for the treatment of ailments such as fever, sore throat, Tuberculosis, convulsions and as sedatives. The aim of this study was to determine biochemical variations in five species and correlate their metabolite profiles to antioxidant activity using a chemometric approach.

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Mine tailing dumps are arguably one of the leading sources of environmental degradation with often both public health and ecologically consequences. The present study investigated the concentration of heavy metals in gold mine tailings, and used high throughput sequencing techniques to determine the microbial community diversity of these tailings using 16S rRNA gene based amplicon sequence analysis. The concentration of detected metals and metalloids followed the order Si > Al > Fe > K > Ca > Mg.

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Urban life has created man-made extreme environments like carwashes. These environments have, however, not been sufficiently explored for mycobiota that can be sources of biotechnologically useful products, as has been the case with natural extreme environments. Using a combination of culture and molecular techniques, fungi from carwash effluents was characterized for production of lipase and cellulase enzymes, nonpolar and polar biotechnologically relevant secondary metabolites and hydrocarbon utilization.

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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.

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Human immunodeficiency virus (HIV)-specific natural killer (CD3- cells), CD4, and CD8 T cellular responses were determined in 79 HIV‐1-infected women in response to HIV‐1 peptide pools (Gag, Pol, Nef, Reg, and Env) with use of a whole‐blood intracellular cytokine staining assay that measures interferon-γ and/or interleukin-2. HIV‐specific CD3- cell responses to any region (Env and Reg predominantly targeted) were associated with lower viral load (P = .031) and higher CD4 T cell count (P = .

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Most infants exposed to HIV-1 in utero and at delivery do not acquire infection. We show that mothers and infants who have CD3-negative cells that respond to HIV-1 peptides are substantially less likely to transmit and acquire infection, respectively. The CD3-negative cells, shown to be NK cells, respond with remarkable specificity and high magnitude to HIV-1 peptides from Env (envelope) and Reg (regulatory) protein regions, as measured by a whole blood intracellular cytokine assay only in the context of HIV-1 infection or exposure.

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Background: There are few data describing the specificity, breadth and magnitude of T cell responses to HIV-1 in infancy.

Methods: HIV-specific CD8+ and CD4+ T cell responses to peptide pools representing Gag, Env, Pol, Nef and the regulatory regions (Reg) were simultaneously measured in 18 perinatally-infected infants and 14 of their chronically-infected mothers, using a whole blood interleukin-2 and interferon-gamma flow cytometric intracellular cytokine staining assay.

Results: HIV-specific CD8+ T cell responses were detected in all the infants aged 6 weeks and older (range 0.

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HIV-specific T-cell responses play an important role in control of infection. Because CCL3 has immune modulatory and antiviral activities, we hypothesized that host CCL3 genotype (CCL3L1 gene duplications) would influence the development of effective HIV-specific immune responses. Copy numbers of CCL3L1 were determined for 71 HIV-infected women, and HIV-specific CD4 and CD8 T-cell responses to overlapping peptide pools spanning the HIV-1 subtype C genome were simultaneously measured by an interferon-gamma and interleukin-2 whole-blood flow cytometric assay.

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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.

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A whole blood peptide mapping intracellular cytokine staining (ICS) assay was developed that allows the direct comparison, at the individual peptide level, of CD4(+) and CD8(+) T-cell responses that span every encoded protein, in patients infected with HIV-1. Whole blood samples from HIV-1 infected patients were stimulated with overlapping synthetic peptides spanning nine subtype C HIV-1 gene regions (Gag, Pol, Nef, Env, Tat, Rev, Vif, Vpu, Vpr). Following stimulation and permeabilization, cells were stained with fluorochrome labelled antibodies to CD3, CD8 (CD4(+) cells were defined as CD8 negative cells), and IL-2 and IFN-gamma.

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Human immunodeficiency virus type 1 (HIV-1)-specific cellular immune responses are elicited in a proportion of infants born to HIV-1-infected mothers and are associated with protection against vertical transmission. To investigate correlates of these HIV-1-specific responses, we examined levels of the immune activation markers neopterin, beta(2)-microglobulin (beta(2)-m), and soluble l-selectin (sl-selectin); the immunomodulatory and hematopoietic factors interleukin-7 (IL-7), stromal-cell-derived factor 1 alpha (CXCL12), and granulocyte-macrophage colony-stimulating factor (GM-CSF); and the immunoregulatory cytokine IL-10 among a group of newborns born to HIV-1-positive mothers who did not receive any antiretroviral drugs for prevention of perinatal HIV-1 transmission. Cellular immune responses to HIV-1 envelope (Env) peptides were also measured.

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The role of CC chemokines in protection against mother-to-child human immunodeficiency virus type 1 (HIV-1) transmission is not well understood. It was observed that mitogen-induced production of CCL3 and CCL4 by cord-blood mononuclear cells was increased among infants born to HIV-positive compared with HIV-negative mothers, and that a deficiency in production of CCL3 was associated with increased susceptibility to intrapartum HIV-1 infection. CCL3-L1 gene copy number was associated with CCL3 production and with vertical transmission.

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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-gamma) production in response to mycobacterial antigens was measured at birth and 6 weeks of age to determine the characteristics of the IFN-gamma response in HIV-exposed infants to Mycobacterium bovis BCG and mycobacterial antigens.

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Although human immunodeficiency virus type 1 (HIV-1) specific CD4 T-helper cells are vital in mediating antiviral defence, little is known concerning the influence of HIV-1 antigenic variation on CD4 T-cell responses. In this study, the amino acid sequences of 5 synthetic HIV-1 envelope peptides used for in vitro stimulation (T2, P18 MN, P18 IIIB, T1 and TH4.1) were compared to the corresponding amino acid sequences of the gp 160 region of viruses isolated from HIV-1 infected children to determine whether variation in the envelope region of HIV-1 was associated with the ability to detect Env-specific T-helper cell responses.

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In infants, the major components of the innate immune system appear weakened, and it has been shown that both polymorphonuclear neutrophil (PMN) production and function are immature. This study was conducted to assess the expression of a number of receptors important to normal PMN function and the integrity of PMN degranulation in cord blood and in uninfected children of varying ages born to human immunodeficiency virus type 1 (HIV-1) seropositive mothers. Although the expression of l-selectin (CD62L) on PMN did not differ between the infants aged 12, 15 and 18 months, the expression of the interleukin-8 (IL-8) receptors CXCR1 and CXCR2, and the complement 5a (C5a) receptor CD88 displayed a similar pattern, with the highest levels expressed on PMN from infants in the 12 month old age group, and declining with age.

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Increased expression of CD38 on CD8(+) T cells is associated with activation of the immune system, progression of HIV disease, and death in adults. The prognostic significance of these cells in HIV-infected children, where the picture is complicated by age-related differences in CD38 expression, remains controversial. Measuring the unimodal expression of CD38 on CD8(+) T cells in adults and children by flow cytometry is best accomplished by quantitating the antigen on the cell surface.

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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.

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