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result(s) for
"Justin du Plessis"
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Zinc preconditioning protects against renal ischaemia reperfusion injury in a preclinical sheep large animal model
Ischaemia–reperfusion injury (IRI) during various surgical procedures, including partial nephrectomy for kidney cancer or renal transplantation, is a major cause of acute kidney injury and chronic kidney disease. Currently there are no drugs or methods for protecting human organs, including the kidneys, against the peril of IRI. The aim of this study was therefore to investigate the reno-protective effect of Zn2+ preconditioning in a clinically relevant large animal sheep model of IRI. Further the reno-protective effectiveness of Zn2+ preconditioning was tested on normal human kidney cell lines HK-2 and HEK293. Anaesthetised sheep were subjected to uninephrectomy and 60 min of renal ischaemia followed by reperfusion. Sheep were preconditioned with intravenous injection of zinc chloride prior to occlusion. Serum creatinine and urea were measured before ischaemia and for 7 days after reperfusion. HK-2 and HEK293 cells were subjected to in vitro IRI using the oxygen- and glucose-deprivation model. Zn2+ preconditioning reduced ischaemic burden determined by creatinine and urea rise over time by ~ 70% in sheep. Zn2+ preconditioning also increased the survival of normal human kidney cells subjected to cellular stress such as hypoxia, hydrogen peroxide injury, and serum starvation. Overall, our protocol incorporating specific Zn2+ dosage, number of dosages (two), time of injection (24 and 4 h prior), mode of Zn2+ delivery (IV) and testing of efficacy in a rat model, a large preclinical sheep model of IRI and cells of human origin has laid the foundation for assessment of the benefit of Zn2+ preconditioning for human applications.
Journal Article
Hypopharyngeal large cell neuroendocrine carcinoma
Neuroendocrine carcinoma (NEC) of the head and neck is rare. We report a case of a 56-year-old man with a 6-week history of dysphagia, a neck mass and weight loss. He was diagnosed with a hypopharyngeal large cell NEC (LCNEC) with metastases to multiple sites. He received two cycles of cisplatin and etoposide. Subsequent restaging scan revealed progressive disease. The patient declined further chemotherapy and died shortly after. This is the third case of LCNEC of hypopharynx reported in the English literature and the first to progress on platinum-based chemotherapy. Although LCNEC of the head and neck is still classified as an atypical carcinoid, there is increasing evidence it is a distinct clinicohistopathological entity that carries an especially poor prognosis. Currently, there is a paucity of data to guide treatment of this rare malignancy.
Journal Article
Characterization of Zalaria obscura Y1223 hydrolases: implications for lignocellulose conversion
Overconsumption of fossil fuel reserves and its adverse effects has sparked interest in the production of second-generation biofuels due to the abundance of lignocellulosic waste and potential energy crops. However, processing costs associated with depolymerization of the cellulose crystalline structure have stalled advancement in cellulosic ethanol production. Current investigations range from identification of novel enzymes for lignocellulose hydrolysis to consolidation of enzyme production into a singular alcohol producing microorganism to potentially reduce cost for commercial processing. In this study, a total of 828 non-
Saccharomyces
and black yeasts were screened for cellulolytic and xylanolytic enzyme activities, whereby 60 isolates were identified that exhibited activity for at least one of the enzymes tested. In doing so, a novel
Zalaria obscura
strain (
Z. obscura
Y1223) was identified and assessed for enzyme activity in multiple growth media. Semi-quantitative assays showed that
Z. obscura
Y1223 produced cellulases optimally in media containing yeast extract, peptone and oat bran, with a pH range between pH 5 and 6 and at 30 °C. Maximum xylanase activity (20.5 U/L/OD
600
) was attained using synthetic complete media supplemented with xylo-oligosaccharides and maximum cellulase activity (7.51 U/L/OD
600
endoglucanase, 1.302 U/L/OD
600
β-glucosidase) was attained when grown in media containing yeast extract, peptone and oat bran. To our knowledge, this is the first study to quantify the cellulolytic and xylanolytic enzyme activities of a
Zalaria
spp., which provides key insight into the availability of unexplored cellulolytic enzymes that could inform the design of organisms engineered for consolidated bioprocessing.
Journal Article
Biocontrol Potential of Selected Phyllospheric Yeasts Against Botrytis cinerea and Fusarium fujikuroi
Ten phyllospheric yeast strains were studied for their potential as biocontrol agents against fruit spoilage mould. The efficacy of these yeasts against Botrytis cinerea and Fusarium fujikuroi was assessed using dual-culture, mouth-to-mouth, radial growth inhibition and post-harvest fruit assays. Additionally, their capacity for producing hydrolytic enzymes was examined. Results from the ten yeasts revealed dual culture antagonism ranging from 41% to 63% against B. cinerea and 23% to 48% against F. fujikuroi, along with radial inhibition ranging from 70% to 100% and 47% to 100%, respectively. Additionally, in vitro inhibition through the production of volatile organic compounds (VOCs) varied from 2% to 46% against B. cinerea and 6% to 64% against F. fujikuroi. Overall, Aureobasidium melanogenum J7, Suhomyces pyralidae Y1117, Dekkera anomala V38, and Rhodotorula diarenensis J43 emerged as the best-performing biocontrol yeasts. Volatile organic compounds produced by the four yeasts were also identified and included in fruit bioassays using pears and tomatoes. Various VOCs, including 1-butanol, 3-methylbutanol, and butyric acid, were linked to the antagonistic properties of the selected yeasts. Lastly, the four chosen yeast strains significantly mitigated post-harvest spoilage caused by B. cinerea and F. fujikuroi in pear and tomato fruits, with D. anomala V38 exhibiting the greatest inhibitory activity. These findings underscore a potential sustainable and efficient approach to reducing mould-induced post-harvest spoilage while reducing reliance on synthetic fungicides.
Journal Article
Modulation of Wine Flavor using Hanseniaspora uvarum in Combination with Different Saccharomyces cerevisiae, Lactic Acid Bacteria Strains and Malolactic Fermentation Strategies
Hanseniaspora uvarum is one of the predominant non-Saccharomyces yeast species found on grapes and in juice, but its effect on lactic acid bacteria (LAB) growth and wine flavor has not been extensively studied. Therefore, the interaction between H. uvarum, two Saccharomyces cerevisiae yeast strains, two LAB species (Lactobacillus plantarum and Oenococcus oeni) in combination with two malolactic fermentation (MLF) strategies was investigated in Shiraz wine production trials. The evolution of the different microorganisms was monitored, non-volatile and volatile compounds were measured, and the wines were subjected to sensory evaluation. Wines produced with H. uvarum in combination with S. cerevisiae completed MLF in a shorter period than wines produced with only S. cerevisiae. Sequential MLF wines scored higher for fresh vegetative and spicy aroma than wines where MLF was induced as a simultaneous inoculation. Wines produced with H. uvarum had more body than wines produced with only S. cerevisiae. The induction of MLF using L. plantarum also resulted in wines with higher scores for body. H. uvarum can be used to reduce the duration of MLF, enhance fresh vegetative aroma and improve the body of a wine.
Journal Article
Impact of Yeast Selection on Volatile Phenol Levels of Wines Produced from Smoked-Exposed Juice
Grapes exposed to smoke can result in wines that have unacceptable high levels of volatile phenols. High volatile phenols levels have a negative impact on wine quality. This study aimed to determine the levels of volatile phenols in wines produced from smoke-exposed juice by a selection of commercial wine yeasts and to determine if yeast selection affected the perception of smokiness in wine. Commercial white and red wine yeasts were screened for the production of volatile phenols in smoke-exposed Chenin Blanc and Merlot juice. Volatile phenol levels were determined by GC-MS/MS and wines were also subjected to sensory evaluation. Volatile phenol levels in smoked wines varied and was affected by yeast strain. The highest guaiacol levels in Chenin Blanc were found in wines fermented with QA23, while Merlot wines that underwent spontaneous alcoholic fermentation contained the highest levels. The levels of volatile phenols differed significantly between the smoked and unsmoked wines, and the sensory results supported the chemical data. Volatile phenols had a negative effect on Chenin Blanc flavor profiles even when the levels were below odor detection thresholds. Yeast selection is important and can affect the volatile phenol levels and flavor profiles of wines.
Journal Article
The Use of Specific Non-Saccharomyces Yeasts as Sustainable Biocontrol Solutions Against Botrytis cinerea on Apples and Strawberries
Apples and strawberries hold significant commercial and nutritional value but face pre- and post-harvest spoilage due to infections by Botrytis cinerea. While spoilage is conventionally managed using synthetic chemicals, there is a growing interest in utilising yeasts as biological control agents. This study aimed to assess the antifungal potential of non-Saccharomyces yeasts Suhomyces pyralidae, Meyerozyma guilliermondii, Pichia kluyveri, Zygoascus hellenicus, and Aureobasidium melanogenum against three B. cinerea strains (B05.10, IWBT-FF1, and PPRI 30807) on agar plates and in post-harvest trials on apples and strawberries. Aureobasidium melanogenum exhibited a broad range of extracellular enzyme production and inhibition rates of 55%, 52%, and 40% against the strains. In volatile organic compound (VOC) assays, P. kluyveri and S. pyralidae achieved 79% and 56% inhibition, respectively, with VOCs like isobutanol, isoamyl alcohol, 2-phenylethanol, isoamyl acetate, and 2-phenethyl acetate identified. In post-harvest trials, S. pyralidae was most effective on apples, with inhibition rates up to of 64%. The commercial fungicide Captan and S. pyralidae and P. kluyveri achieved 100% inhibition against the B. cinerea strains B05.10 and IWBT-FF1 on strawberries. These findings highlight the potential of the selected yeast species as biological control agents against B. cinerea, warranting further research into their application in commercial fruit protection.
Journal Article
Inferring enterovirus D68 transmission dynamics from the genomic data of two 2022 North American outbreaks
Enterovirus D68 (EV-D68) has emerged as a significant cause of acute respiratory illness in children globally, notably following its extensive outbreak in North America in 2014. A recent outbreak of EV-D68 was observed in Ontario, Canada, from August to October 2022. Our phylogenetic analysis revealed a notable genetic similarity between the Ontario outbreak and a concurrent outbreak in Maryland, USA. Utilizing Bayesian phylodynamic modeling on whole genome sequences (WGS) from both outbreaks, we determined the median peak time-varying reproduction number (R t ) to be 2.70, 95% HPD (1.76, 4.08) in Ontario and 2.10, 95% HPD (1.41, 3.17) in Maryland. The R t trends in Ontario closely matched those derived via EpiEstim using reported case numbers. Our study also provides new insights into the median infection duration of EV-D68, estimated at 7.94 days, 95% HPD (4.55, 12.8) in Ontario and 10.8 days, 95% HPD (5.85, 18.6) in Maryland, addressing the gap in the existing literature surrounding EV-D68’s infection period. We observed that the estimated Time since the Most Recent Common Ancestor (TMRCA) and the epidemic’s origin coincided with the easing of COVID-19 related social contact restrictions in both areas. This suggests that the relaxation of non-pharmaceutical interventions, initially implemented to control COVID-19, may have inadvertently facilitated the spread of EV-D68. These findings underscore the effectiveness of phylodynamic methods in public health, demonstrating their broad application from local to global scales and underscoring the critical role of pathogen genomic data in enhancing public health surveillance and outbreak characterization.
Journal Article
Uncrewed surface vehicles in the Global Ocean Observing System: a new frontier for observing and monitoring at the air-sea interface
Observing air-sea interactions on a global scale is essential for improving Earth system forecasts. Yet these exchanges are challenging to quantify for a range of reasons, including extreme conditions, vast and remote under-sampled locations, requirements for a multitude of co-located variables, and the high variability of fluxes in space and time. Uncrewed Surface Vehicles (USVs) present a novel solution for measuring these crucial air-sea interactions at a global scale. Powered by renewable energy (e.g., wind and waves for propulsion, solar power for electronics), USVs have provided navigable and persistent observing capabilities over the past decade and a half. In our review of 200 USV datasets and 96 studies, we found USVs have observed a total of 33 variables spanning physical, biogeochemical, biological and ecological processes at the air-sea transition zone. We present a map showing the global proliferation of USV adoption for scientific ocean observing. This review, carried out under the auspices of the ‘Observing Air-Sea Interactions Strategy’ (OASIS), makes the case for a permanent USV network to complement the mature and emerging networks within the Global Ocean Observing System (GOOS). The Observations Coordination Group (OCG) overseeing GOOS has identified ten attributes of an in-situ global network. Here, we discuss and evaluate the maturation of the USV network towards meeting these attributes. Our article forms the basis of a roadmap to formalise and guide the global USV community towards a novel and integrated ocean observing frontier.
Journal Article