Search

The rest-breaking agent, hydrogen cyanamide (HC), can substitute insufficient chill unit accumulation in Vitis vinifera and induce uniform bud-break; however, due to its toxicity it is being banned. In South Africa, red seedless grapes, including V. vinifera Crimson Seedless (CS), are the largest table grape export group; therefore, replacing HC in V. vinifera CS is crucial. This study aimed to confirm the molecular triggers induced by HC and assess the bud-break-enhancing abilities of commercial plant biostimulants. Forced bud-break assay experiments using V. vinifera CS single-node cuttings and a small-scale field trial were performed. Results demonstrated that increased chill unit accumulation (CUA) reduced HC efficacy. Bud-break started between 10 and 20 days after treatment, irrespective of final CUA. The small-scale field trial found that HC 3% and biostimulants were similar to the negative control. The treatment of dormant grapevine compound buds with nitric oxide (NO), hydrogen peroxide (H2O2), and hypoxia trigger dormancy release to a certain extent, supporting the molecular models proposed for HC action. NO, H2O2, and hypoxia, in combination with PBs, may potentially replace HC; however, this needs to be confirmed in future experiments. [ABSTRACT FROM AUTHOR]

Bulbine frutescens is an indigenous succulent medicinal plant in South Africa. The plant is commonly used traditionally for the treatment of skin related ailments. B. frutescens has been reported to possess antioxidant, anti-viral and antimicrobial properties. To date, most studies have been conducted on the leaves, while limited reports have been documented on the roots, as well as comparative analyses between both plant parts. The aim of this study was to determine the phytochemical content, antioxidant and antibacterial activities in the leaves and roots of B. frutescens. Methanolic extracts of each plant part were assessed on the phytochemical analysis, antioxidant (DPPH, hydrogen peroxide, metal chelating) and antibacterial activity against S. aureus and E. coli. The results from the phytochemical screening showed that the leaves contained more phytochemical groups than the roots. The roots displayed higher total phenolics (991.7 ± 54.1 mg/g GAE), total flavonoid (285.8 ± 60.6 mg/g QE) and total tannin contents (1698.75 ± 28.15 mg/g GAE) than the leaves. The roots also showed a stronger antioxidant activity in DPPH (3.43 ± 0.16 mg/ml) and metal chelating (0.54 ± 0.01 mg/ml) assays, compared to the leaves, which only showed a higher scavenging power against hydrogen peroxide radicals (1.48 ± 0.02 mg/ml) than the roots. Both plant parts showed intermediate zones of inhibition (10-19 mm) against both bacterial strains, with the exception of the leaves which had a 20.67 ± 0.67 mm inhibition against S. aureus. These results validate the uses of both leaves and roots of B. frutescens in traditional medicine and further suggests for the application of the roots in pharmaceutical and cosmetic industries. [ABSTRACT FROM AUTHOR]

Background: Contact lens care regimens appear to be prescribed based on familiarity or by matching contact lens brands rather than consideration to efficacy. Aim: This study compared the effectiveness of multipurpose and peroxide cleaning solutions on low- and high-water content ionic and non-ionic soft contact lenses, in removing Pseudomonas aeruginosa (P. aeruginosa). Setting: The laboratory work was conducted by health science students in a graduate level programme in the microbiology laboratory at a university in south-eastern South Africa. Methods: A quantitative analytical experimental design was used. Four groups (labelled I, II, III and IV) of soft contact lenses, varied ionicity and water content were inoculated with P. aeruginosa and then exposed to three solutions containing antimicrobial ingredients, polyaminopropyl biguanide (Dymed), hydrogen peroxide (H2O2) and polyquaternium-1 (Polyquad). Each group contained 14 soft contact lenses, with the exception of Group III in which eight lenses were used. Saline served as the control. After 18 h, the remaining colony-forming units were counted using visual inspection as an indicator of efficacy against P. aeruginosa. Results: The solution containing H2O2 was found to be the most effective in removing P. aeruginosa from all Food and Drug Administration (FDA) groups of contact lenses whilst Dymed was found to be comparatively ineffective for this organism. Water content and ionicity had no effect on the efficacy of the solutions. Conclusion: Practitioners should consider the efficacy of the active ingredients against microorganisms when dispensing contact lens solutions, particularly for contact lens wearers at risk for P. aeruginosa infections. [ABSTRACT FROM AUTHOR]

The widespread adoption of sediment fingerprinting methodologies for the purpose of catchment management has been restricted by the high cost of tracer analysis as well as the potential for significant uncertainties to be present in results. Sediment colour has shown potential to be an inexpensive tracer able to discriminate between sediment sources. However, at present colour has not been demonstrated to be conservative during sediment erosion and transport. Sediment particle size and organic matter have been shown to strongly affect sediment colour, introducing significant uncertainties associated with its use. This study aimed to assess the suitability of colour as a tracer when it is measured using a commercially available colour scanner. The use of hydrogen peroxide (H 2 O 2 ) to decompose sediment-associated organic matter was assessed as a means of minimising uncertainty. The impact of particle size on the accurate use of colour signatures as a tracer was also assessed. It was concluded that colour performed comparably to mineral magnetic signatures and showed good potential for use as a tracer. The use of H 2 O 2 pre-treatment and limitation of the analysis to either the <32 μm or the >32 μm fraction of the samples were indicated to be important methods to limit uncertainties associated with organic matter and particle size. The methods used were considerably more time and cost effective than the measurement of most conventional tracers. [ABSTRACT FROM AUTHOR]

Haemostatic- and oxidative stress markers are associated with increased cardiovascular risk. In the black population, evidence exists that both an imbalance in the haemostatic system and oxidative stress link with the development of hypertension. However, it is unclear whether these two risk components function independently or are related, specifically in the black population, who is known to have a high prevalence of stroke. We aimed to investigate associations between the haemostatic system and oxidative stress in black and white South Africans. We performed a cross-sectional study including 181 black (mean age, 44; 51.4% women) and 209 white (mean age, 45; 51.7% women) teachers. Several markers of the haemostatic- (von Willebrand factor, fibrinogen, plasminogen activator inhibitor-1,d-dimer and clot lysis time) and oxidant–antioxidant (serum peroxides, total glutathione, glutathione peroxidase- and glutathione reductase activities) systems were measured. Along with a worsened cardiovascular profile, the black group had higher haemostatic-, inflammation- and oxidative stress markers as well as decreased glutathione peroxidase activity. In multiple regression analyses, fibrinogen was positively associated with serum peroxides (p < 0.001) in both ethnic groups. In the black population, we found negative associations of von Willebrand factor and clot lysis time with glutathione peroxidase activity (p ≤ 0.008), while a positive association existed between clot lysis time and serum peroxides (p = 0.011) in the white population. We conclude that in the black population, decreased GPx activity accompanies an altered haemostatic profile, while in the white population associations may suggest that serum peroxides impair fibrin clot lysis. [ABSTRACT FROM AUTHOR]

Background: Bacterial vaginosis (BV), which is highly prevalent in the African population, is one of the most common vaginal syndromes affecting women in their reproductive age placing them at increased risk for sexually transmitted diseases including infection by human immunodeficiency virus-1. The vaginal microbiota of a healthy woman is often dominated by the species belonging to the genus Lactobacillus namely L. crispatus, L. gasseri, L. jensenii and L. iners, which have been extensively studied in European populations, albeit less so in South African women. In this study, we have therefore identified the vaginal Lactobacillus species in a group of 40 African women from Soweto, a township on the outskirts of Johannesburg, South Africa. Methods: Identification was done by cultivating the lactobacilli on Rogosa agar, de Man-Rogosa-Sharpe (MRS) and Blood agar plates with 5% horse blood followed by sequencing of the 16S ribosomal DNA. BV was diagnosed on the basis of Nugent scores. Since some of the previous studies have shown that the lack of vaginal hydrogen peroxide (H2O2) producing lactobacilli is associated with bacterial vaginosis, the Lactobacillus isolates were also characterised for their production of H2O2. Results: Cultivable Lactobacillus species were identified in 19 out of 21 women without BV, in three out of five women with intermediate microbiota and in eight out of 14 women with BV. We observed that L. crispatus, L. iners, L. jensenii, L. gasseri and L. vaginalis were the predominant species. The presence of L. crispatus was associated with normal vaginal microbiota (P = 0.024). High level of H2O2 producing lactobacilli were more often isolated from women with normal microbiota than from the women with BV, although not to a statistically significant degree (P = 0.064). Conclusion: The vaginal Lactobacillus species isolated from the cohort of South African women are similar to those identified in European populations. In accordance with the other published studies, L. crispatus is related to a normal vaginal microbiota. Hydrogen peroxide production was not significantly associated to the BV status which could be attributed to the limited number of samples or to other antimicrobial factors that might be involved. [ABSTRACT FROM AUTHOR]

The dusky kob Argyrosomus japonicus is an emerging aquaculture species in South Africa. To support industry growth, existing hatcheries frequently sell or donate excess eggs to neighbouring farms, raising concern over the potential transfer of infectious disease agents. Chemical disinfectants are frequently used to prevent transmission of diseases, but their application has shown large variations between finfish species and very little is known about the efficacy and impact of disinfectants on dusky kob eggs or larvae. A thorough understanding of the bacterial communities associated with specific fish species can inform the need for specific chemical agents and guide a more targeted approach for disease control and treatment. Therefore, this study used next generation sequencing (NGS, 16S rDNA gene) and downstream bioinformatics analysis to describe the bacterial microbiome associated with the eggs and rearing water of dusky kob. Four chemical disinfectants [chloramine-T (C-T), povo‑iodine (P I), hydrogen peroxide (H 2 O 2) & formaldehyde (CH 2 O)], applied at different concentrations and times, were then tested for their ability to disinfect eggs and seawater. The impact of each disinfectant on early larval development was also assessed. A total of 11,605 individual bacterial operational transcriptional units (OTUs) were identified from the dusky kob egg (7352 OTUs) and hatchery water (4253 OTUs) samples. Non-metric multidimensional scaling (NMDS) analysis revealed distinct differences in the composition of the microbiota associated with the egg and seawater samples. A moderate level of bacterial diversity was observed in all samples, with the seawater samples dominated by Rhodobacteraceae (65%) and Flavobacteriaceae (14%); whereas egg samples were dominated by Pseudoalteromonadaceae (49%), Vibrionaceae (27%) and Colwelliaceae (8%). A classical univariate statistical comparison identified 6 differentially abundant OTUs at phylum level, 12 at family level and 19 at genus level; with members of the family Vibrionaceae found to be significantly (P = 0.0011) more abundant on dusky kob eggs samples. All tested chemical disinfectants were capable of reducing the bacterial load in seawater in a dose dependent manner, with the number of culturable bacteria on eggs decreasing significantly following exposure to P I and CH 2 O for five minutes (43% and 88% reduction in CFUs, respectively), compared with C-T and H 2 O 2 (3% & 10%). Similarly, P I and CH 2 O significantly decreased the culturability of Vibrio species on eggs (79% & 75%), compared with C-T and H 2 O 2 (12% & 14%). None of the disinfectants appeared to have any adverse impact on larval growth and morphology. • Bacteria associated with dusky kob eggs are distinct from the surrounding seawater. • Proteobacteria and Bacteroidetes are dominant phyla on eggs and in seawater. • Povo‑iodine and formaldehyde significantly reduce bacteria associated with eggs and seawater. • Disinfectants have no adverse impact on larval growth and morphology. [ABSTRACT FROM AUTHOR]

Evonik Industries is significantly expanding the capacity of its hydrogen peroxide (H2O2).plant in Umbogintwini, South Africa. [Copyright &y& Elsevier]

A method is presented for the determination of antimony in whole human blood samples with an ICP-MS instrument using a quadrupole mass analyzer. A nitric acid/hydrogen peroxide open digestion procedure was employed for the blood sample treatment and preparation for analysis. The precision and accuracy of the method were evaluated by analyzing several Seronorm trace elements whole blood reference materials. The precision of the method at various antimony levels was better than 4% RSD and the recovery was greater than 92% at all levels. The detection limit, calculated as three times the standard deviation of the blank (3sigma, n= 12), was 0.03 microg L(-1). The method was successfully applied for the determination of antimony in blood samples from school children in rural areas of Kwazulu/Natal, South Africa and adults from Dearborn, Michigan. Blood antimony levels ranged from <0.03 to 3.82 microg L(-1) in children and 1.40 to 4.35 microg L(-1) for adults.