Genetic Variants of Cytochrome b-245, Alpha Polypeptide Gene and Premature Acute Myocardial Infarction Risk in An Iranian Population

Background: Oxidative stress induced by superoxide anion plays critical roles in the pathogenesis of coronary artery disease (CAD) and hence acute myocardial infarction (AMI). The major source of superoxide production in vascular smooth muscle and endothelial cells is the NADPH oxidase complex. An essential component of this complex is p22phox, that is encoded by the cytochrome b-245, alpha polypeptide (CYBA) gene. The aim of this study was to investigate the association of CYBA variants (rs1049255 and rs4673) and premature acute myocardial infarction risk in an Iranian population. Methods: The study population consisted of 158 patients under the age of 50 years, with a diagnosis of premature AMI, and 168 age-matched controls with normal coronary angiograms. Genotyping of the polymorphisms was performed by the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Results: There was no association between the genotypes and allele frequencies of rs4673 polymorphism and premature acute myocardial infarction (P>0.05). A significant statistical association was observed between the genotypes distribution of rs1049255 polymorphism and AMI risk (P=0.037). Furthermore, the distribution of AA+AG/GG genotypes was found to be statistically significant between the two groups (P=0.011). Conclusions: Our findings indicated that rs1049255 but not rs4673 polymorphism is associated with premature AMI

Experimental Investigation of Ice Rubble Behaviour and Strength in Punch Tests

The report summarises the results from three series of plunge tests on ice rubble conducted at the University of Calgary, and interpretation of these results. The tests were conducted as two-dimensional plane strain experiments in a transparent tank that permitted video recording of the rubble behaviour during the tests. The majority of the tests were conducted using standard fresh-water ice cubes manufactured using commercial ice making machines, while the most recent tests were conducted using larger ice pieces. The observations of the behaviour of the rubble during the tests suggested that there was a significant difference in behaviour observed at low and high loading speeds. At low speeds, well-defined failure planes were observed, and, for unconsolidated rubble, the behaviour could be described as purely frictional. As the ice was permitted to consolidate, the addition of local regelation altered the value of the angle of friction, but the observed behaviour was little changed. Over the range of low speed tests ( to 40 mm/sec) there was no appreciable effect of speed on friction angle. However, there is some effect of rubble thickness. At high speeds of loading, no clearly defined failure planes were observed. The failure could be described as gradual, with the disturbance of the ice rubble taking place within the mass of the rubble. The analogy used for the interpretation of the strength of the rubble (plate pull-out in granular materials) was not applicable to these tests. The analysis of these results, and the extension of the test programme for the larger ice pieces, is on-going.NRC publication: Ye