Browsing by Author "Nkambule, Bongani B."

Now showing 1 - 6 of 6
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    Cardioprotective potential of N-acetyl cysteine against hyperglycaemia-induced oxidative damage : a protocol for a systematic review
    (BMC (part of Springer Nature), 2017) Dludla, Phiwayinkosi V.; Nkambule, Bongani B.; Dias, Stephanie C.; Johnson, Rabia
    Background: Hyperglycaemia-induced oxidative damage is a well-established factor implicated in the development of diabetic cardiomyopathy (DCM) in diabetic individuals. Some of the well-known characteristics of DCM include increased myocardial left ventricular wall thickness and remodelling that result in reduced cardiac efficiency. To prevent this, an increasing number of pharmacological compounds such as N-acetyl cysteine (NAC) are explored for their antioxidant properties. A few studies have shown that NAC can ameliorate hyperglycaemia-induced oxidative damage within the heart. Hence, the objective of this review is to synthesise the available evidence pertaining to the cardioprotective role of NAC against hyperglycaemia-induced oxidative damage and thus prevent DCM. Methods: This systematic review protocol will be reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement. We will perform a comprehensive search on major databases such as EMBASE, Cochrane Library, PubMed and Google scholar for original research articles published from January 1960 to March 2017. We will only report on literature that is available in English. Two authors will independently screen for eligible studies using pre-defined criteria, and data extraction will be done in duplicate. All discrepancies will be resolved by consensus or consultation of a third reviewer. The quality of studies will be checked using Cochrane Risk of Bias Assessment Tool and The Joanna Briggs Institute (JBI) Critical Appraisal tools for non-randomised experimental studies. Heterogeneity across studies will be assessed using the Cochrane Q statistic and the inconsistency index (I2). We will use the random effects model to calculate a pooled estimate. Discussion: Although several studies have shown that NAC can ameliorate hyperglycaemia-induced oxidative damage within the heart, this systematic review will be the first pre-registered synthesis of data to identify the cardioprotective potential of NAC against hyperglycaemia-induced oxidative damage. This result will help guide future research evaluating the cardioprotective role of NAC against DCM and better identify possible mechanisms of action for NAC to prevent oxidative damage with a diabetic heart.
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    Coenzyme Q10 supplementation improves adipokine levels and alleviates inflammation and lipid peroxidation in conditions of metabolic syndrome : a meta-analysis of randomized controlled trials
    (MDPI, 2020-05-04) Dludla, Phiwayinkosi V.; Orlando, Patrick; Silvestri, Sonia; Marcheggiani, Fabio; Cirilli, Ilenia; Nyambuya, Tawanda M.; Mxinwa, Vuyolwethu; Mokgalaboni, Kabelo; Nkambule, Bongani B.; Johnson, Rabia; Mazibuko-Mbeje, Sithandiwe E.; Muller, Christo J. F.; Louw, Johan; Tiano, Luca
    Evidence from randomized controlled trials (RCTs) suggests that coenzyme Q10 (CoQ10) can regulate adipokine levels to impact inflammation and oxidative stress in conditions of metabolic syndrome. Here, prominent electronic databases such as MEDLINE, Cochrane Library, and EMBASE were searched for eligible RCTs reporting on any correlation between adipokine levels and modulation of inflammation and oxidative stress in individuals with metabolic syndrome taking CoQ10. The risk of bias was assessed using the modified Black and Downs checklist, while the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool was used to evaluate the quality of evidence. Results from the current meta-analysis, involving 318 participants, showed that CoQ10 supplementation in individuals with metabolic syndrome increased adiponectin levels when compared to those on placebo (SMD: 1.44 [95% CI: −0.13, 3.00]; I2 = 96%, p < 0.00001). Moreover, CoQ10 supplementation significantly lowered inflammation markers in individuals with metabolic syndrome in comparison to those on placebo (SMD: −0.31 [95% CI: −0.54, −0.08]; I2 = 51%, p = 0.07). Such benefits with CoQ10 supplementation were related to its ameliorative effects on lipid peroxidation by reducing malondialdehyde levels, concomitant to improving glucose control and liver function. The overall findings suggest that optimal regulation of adipokine function is crucial for the beneficial effects of CoQ10 in improving metabolic health.
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    Inflammation and oxidative stress in an obese state and the protective effects of gallic acid
    (MDPI, 2019) Dludla, Phiwayinkosi V.; Nkambule, Bongani B.; Jack, Babalwa; Mkandla, Zibusiso; Mutize, Tinashe; Silvestri, Sonia; Orlando, Patrick; Tiano, Luca; Louw, Johan; Mazibuko-Mbeje, Sithandiwe E.
    ENGLISH ABSTRACT: Metabolic complications in an obese state can be aggravated by an abnormal inflammatory response and enhanced production of reactive oxygen species. Pro-inflammatory response is known to be associated with the formation of toxic reactive oxygen species and subsequent generation of oxidative stress. Indeed, adipocytes from obese individuals display an altered adipokine profile, with upregulated expression and secretion of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin (IL-6). Interestingly, natural compounds, including phenolic enriched foods are increasingly explored for their ameliorative effects against various metabolic diseases. Of interest is gallic acid, a trihydroxybenzoic acid that has progressively demonstrated robust anti-obesity capabilities in various experimental models. In addition to reducing excessive lipid storage in obese subjects, gallic acid has been shown to specifically target the adipose tissue to suppress lipogenesis, improve insulin signaling, and concomitantly combat raised pro-inflammatory response and oxidative stress. This review will revise mechanisms involved in the pathophysiological effects of inflammation and oxidative stress in an obese state. To better inform on its therapeutic potential and improvement of human health, available evidence reporting on the anti-obesity properties of gallic acid and its derivatives will be discussed, with emphases on its modulatory effect on molecular mechanisms involved in insulin signaling, inflammation and oxidative stress.
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    N-Acetyl cysteine ameliorates hyperglycemia-induced cardiomyocyte toxicity by improving mitochondrial energetics and enhancing endogenous Coenzyme Q9/10 levels
    (Elsevier, 2019) Dludla, Phiwayinkosi V.; Orlando, Patrick; Silvestri, Sonia; Mazibuko-Mbeje, Sithandiwe E.; Johnson, Rabia; Marcheggiani, Fabio; Cirilli, Ilenia; Muller, Christo J. F.; Louwa, Johan; Obonye, Nnini; Nyawo, Thembeka; Nkambule, Bongani B.; Tiano, Luca
    ENGLISH ABSTRACT: The diabetic heart has been linked with reduced endogenous levels of coenzyme Q9/10 (CoQ), an important antioxidant and component of the electron transport chain. Although CoQ has displayed cardioprotective potential in experimental models of diabetes, the impact of N-acetyl cysteine (NAC) on mitochondrial energetics and endogenous levels of CoQ remains to be clarified. To explore these effects, high glucose-exposed H9c2 cardiomyocytes were used as an experimental model of hyperglycemia-induced cardiac injury. The results showed that high glucose exposure caused an increased production of reactive oxygen species (ROS), which was associated with impaired mitochondrial energetics as confirmed by a reduction of maximal respiration rate and depleted ATP levels. These detrimental effects were consistent with significantly reduced endogenous CoQ levels and accelerated cell toxicity. Although metformin demonstrated similar effects on mitochondrial energetics and cell viability, NAC demonstrated a more pronounced effect in ameliorating cytosolic and mitochondrial ROS production. Interestingly, the ameliorative effects of NAC against hyperglycemia-induced injury were linked with its capability to enhance endogenous CoQ levels. Although such data are to be confirmed in other models, especially in vivo studies, the overall findings provide additional evidence on the therapeutic mechanisms by which NAC protects against diabetes-induced cardiac injury.
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    Physical exercise potentially targets epicardial adipose tissue to reduce cardiovascular disease risk in patients with metabolic diseases : oxidative stress and inflammation emerge as major therapeutic targets
    (MDPI, 2021-11-04) Nyawo, Thembeka A.; Pheiffer, Carmen; Mazibuko-Mbeje, Sithandiwe E; Mthembu, Sinenhlanhla X. H.; Nyambuya, Tawanda M.; Nkambule, Bongani B.; Sadie-Van Gijsen, Hanel; Strijdom, Hans; Tiano, Luca; Dludla, Phiwayinkosi V.
    ENGLISH ABSTRACT: Excess epicardial adiposity, within a state of obesity and metabolic syndrome, is emerging as an important risk factor for the development of cardiovascular diseases (CVDs). Accordingly, increased epicardial fat thickness (EFT) implicates the exacerbation of pathological mechanisms involving oxidative stress and inflammation within the heart, which may accelerate the development of CVDs. This explains increased interest in targeting EFT reduction to attenuate the detrimental effects of oxidative stress and inflammation within the setting of metabolic syndrome. Here, we critically discuss clinical and preclinical evidence on the impact of physical exercise on EFT in correlation with reduced CVD risk within a setting of metabolic disease. This review also brings a unique perspective on the implications of oxidative stress and inflammation as major pathological consequences that link increased EFT to accelerated CVD risk in conditions of metabolic disease.
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    Platelet, monocyte and neutrophil activation and glucose tolerance in South African Mixed Ancestry individuals
    (Nature Research, 2017) Davison, Glenda M.; Nkambule, Bongani B.; Mkandla, Zibusiso; Hon, Gloudina M.; Kengne, Andre P.; Erasmus, Rajiv T.; Matsha, Tandi E.
    Platelet activation has been described in patients with chronic inflammation, however in type 2 diabetes mellitus it remains controversial. We compared levels of platelet leucocyte aggregates, monocyte and granulocyte activation across glucose tolerance statuses in mixed ancestry South Africans. Individuals (206) were recruited from Bellville-South, Cape Town, and included 66% with normal glucose tolerance, 18.7% pre-diabetes, 8.7% screen-detected diabetes and 6.3% known diabetes. Monocyte and neutrophil activation were measured by calculating the percentage of cells expressing CD142 and CD69 while platelet monocyte aggregates were defined as CD14++ CD42b+ events and platelet neutrophil aggregates as CD16++ CD42b+ events. The percentage of monocytes and neutrophils expressing CD69 and CD142 was significantly higher in known diabetes and prediabetes, but, lowest in screen-detected diabetes (both p ≤ 0.016). The pattern was similar for platelet monocyte and neutrophil aggregates (both p ≤ 0.003). In robust linear regressions adjusted for age and gender, known diabetes was significantly and positively associated with the percentage of monocytes expressing CD69 [beta 11.06 (p = 0.016)] and CD42b (PMAs) [19.51 (0.003)] as well as the percentage of neutrophils expressing CD69 [14.19 (<0.0001)] and CD42b [17.7 (0.001)]. We conclude that monitoring platelet activation in diagnosed diabetic patients may have a role in the management and risk stratification.