26 research outputs found

    Allosteric Enzyme-Based Biosensors-Kinetic Behaviours of Immobilised L-Lysine-α-Oxidase from Trichoderma viride: pH Influence and Allosteric Properties

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    The present study describes the kinetics of L-lysine-α-oxidase (LO) from Trichoderma viride immobilised by co-crosslinking onto the surface of a Pt electrode. The resulting amperometric biosensor was able to analyse L-lysine, thus permitting a simple but thorough study of the kinetics of the immobilised enzyme. The kinetic study evidenced that LO behaves in an allosteric fashion and that cooperativity is strongly pH-dependent. Not less important, experimental evidence shows that cooperativity is also dependent on substrate concentration at high pH and behaves as predicted by the Monod-Wyman-Changeux model for allosteric enzymes. According to this model, the existence of two different conformational states of the enzyme was postulated, which differ in Lys species landing on LO to form the enzyme-substrate complex. Considerations about the influence of the peculiar LO kinetics on biosensor operations and extracorporeal reactor devices will be discussed as well. Not less important, the present study also shows the effectiveness of using immobilised enzymes and amperometric biosensors not only for substrate analysis, but also as a convenient tool for enzyme kinetic studies

    Causes of sudden cardiac death in young athletes and non-athletes: systematic review and meta-analysis: Sudden cardiac death in the young

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    Introduction: The etiology of sudden cardiac death (SCD) in young people continues to attract much attention. This meta-analysis aimed to identify the most frequent causes of SCD in individuals aged ≤35 years, the differences between athletes and non-athletes and geographic areas. Methods: Studies published between 01/01/1990 and 01/31/2020 and evaluating post-mortem the aetiology of SCD in young individuals (≤35 years) were included. Individuals were divided into athletes and non-athletes. Studies that did not report separate data between athletes and non-athletes were excluded. Results: Thirty-four studies met the inclusion criteria, and a total population of 5,060 victims of SCD were analyzed (2,890 athletes, 2,170 non-athletes). Comparing the causes of SCD between athletes and non-athletes, non-ischemic left ventricular scar (NILVS) (5.1% vs. 1.1%, p=0.01) was more frequent in the former, while coronary artery disease (CAD) (19.6% vs. 9.1%, p=0.009), arrhythmogenic cardiomyopathy (ACM) (11.5% vs. 4.7%, p=0.03) and channelopathies (8.4% vs. 1.9%, p=0.02) were more frequent in the latter. In studies published in the last decade, hypertrophic cardiomyopathy (HCM) (p=0.002), dilated cardiomyopathy (p=0.047), and anomalous origin of coronary arteries (AOCA) (p=0.009) were more frequently the causes of SCD in athletes while aortic dissection (0.022) was the cause in non-athletes. HCM (p=0.01) and AOCA (p=0.004) were more frequently the causes of SCD in the US while ACM (p=0.001), structurally normal heart (p=0.02), and channelopathies (p=0.02) were more frequent in Europe. Conclusions: Among the causes of SCD, NILVS was the more frequent cause in athletes, while CAD, ACM and channelopathies were more frequent causes in non-athletes. The causes of SCD differ between the US and Europe
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