Browsing by Author "Joseph, Danzil E."

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    Glycation abolishes the cardioprotective effects of albumin during ex vivo ischemia-reperfusion
    (Wiley Open Access, 2017) Mapanga, Rudo F.; Joseph, Danzil E.; Saieva, Marco; Boyer, Florence; Rondeau, Philippe; Bourdon, Emmanuel; Essop, M. Faadiel
    Hyperglycemia‐induced oxidative stress plays a key role in the onset/progression of cardiovascular diseases. For example, it can trigger formation of advanced glycation end (AGE) products with ischemia‐reperfusion performed under hyperglycemic conditions. For this study, we hypothesized that albumin modified by glycation loses its unique cardioprotective properties in the setting of ischemia‐reperfusion under high glucose conditions. Here, ex vivo rat heart perfusions were performed under simulated normo‐ and hyperglycemic conditions, that is Krebs‐Henseleit buffer containing 11 mmol/L and 33 mmol/L glucose, respectively, ± normal or glycated albumin preparations. The perfusion protocol consisted of a 60 min stabilization step that was followed by 20 min of global ischemia and 60 min reperfusion. Additional experiments were completed to determine infarct sizes in response to 20 min regional ischemia and 120 min reperfusion. At the end of perfusions, heart tissues were isolated and evaluated for activation of the AGE pathway, oxidative stress, and apoptosis. Our data reveal that native bovine serum albumin treatment elicited cardioprotection (improved functional recovery, decreased infarct sizes) under high glucose conditions together with enhanced myocardial antioxidant capacity. However, such protective features are lost with glycation where hearts displayed increased infarct sizes and poor functional recovery versus native albumin treatments. Myocardial antioxidant capacity was also lowered together with activation of the intracellular AGE pathway. These data therefore show that although albumin acts as a cardioprotective agent during ischemia‐reperfusion, it loses its cardioprotective and antioxidant properties when modified by glycation.
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    The impact of sugar-sweetened beverage intake on rat cardiac function
    (Elsevier, 2019-03-12) Driescher, Natasha; Joseph, Danzil E.; Human, Veronique R.; Ojuka, Edward; Cour, Martin; Hadebe, Nkanyiso; Bester, Dirk; Marnewick, Jeanine L.; Lecour, Sandrine; Lochner, Amanda; Essop, M. Faadiel
    Aims: Although there is evidence linking sugar-sweetened beverage (SSB) intake with the development of cardio-metabolic diseases, the underlying mechanisms remain unclear. The current study therefore evaluated the effects of SSB consumption by establishing a unique in-house in vivo experimental model. Main methods: Male Wistar rats were divided into two groups: a) one consuming a popular local SSB (SSB- Jive), and b) a control group (Control-water) for a period of three and six months (n = 6 per group), respectively. Rats were gavaged on a daily basis with an experimental dosage amounting to half a glass per day (in human terms) (SSB vs. water). Cardiac function was assessed at baseline (echocardiography) and following ex vivo ischemia-reperfusion of the isolated perfused working rat heart. Oral glucose tolerance tests and mitochondrial respiratory analyses were also performed. In addition, the role of non-oxidative glucose pathways (NOGPs), i.e. the polyol pathway, hexosamine biosynthetic pathway (HBP) and PKC were assessed. Key findings: These data show that SSB intake: a) resulted in increased weight gain, but did not elicit major effects in terms of insulin resistance and cardiac function after three and six months, respectively; b) triggered myocardial NOGP activation after three months with a reversion after six months; and c) resulted in some impairment in mitochondrial respiratory capacity in response to fatty acid substrate supply after six months. Significance: SSB intake did not result in cardiac dysfunction or insulin resistance. However, early changes at the molecular level may increase risk in the longer term.