Polymorphic Causes of Atherosclerosis

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Polymorphic Causes of Atherosclerosis

Introduction

Guzik et al. (2000) argued that the role of oxidative stress in the pathogenesis of vascular diseases such as atherosclerosis is critical. The increase in superoxide anion production causes an increase in the oxidative stress and reduces the bioactivity of nitric oxide in vascular diseases. The role of NAD(P)H oxidase as a source of superoxide anions is of great significance and one of its subunit p22phox is predominantly expressed in different coronary disorders. It has been established in the preliminary research studies that a possible association exists between atherosclerosis and the polymorphism seen in the p22phox residue of CYBA gene encoding NAD (P) H oxidase. The researchers tested their relationship by examining the relationship between CYBA C242T polymorphism and the levels of superoxide generation in the blood vessels of humans.

Ishigami et al. (1995) have worked on the connection between the polymorphism of angiotensin-converting enzyme (ACE) gene and different cardiovascular diseases such as coronary atherosclerosis. The plasma activity of ACE has been related to the carotid-wall thickening. Many researchers have postulated that exposure to raised levels of plasma ACE on a long-term basis can cause structural changes in the vessel walls. It has been postulated that preeclampsia and essential hypertension are linked with mutation in the genes encoding angiotensin. These facts reflect that renin-angiotensin system might be involved in advancement of cardiovascular diseases. The study considered the role of molecular variants of the angiotensinogen gene as a genetic cause of coronary atherosclerosis. The researchers analyzed used polymerase chain reaction (PCR) to find the point mutations in the angiotensinogen gene. The frequencies of these alleles were compared in atherosclerotic patients as well as the control subjects.

Zhang et al. (1999) studied the polymorphism of Gelatinase B, a type of matrix metalloproteinase possessing proteolytic properties against the proteins in the connective tissue. Gelatinase B is of particular significance in the remodeling procedures in the connective tissue and previous studies have associated it with atherogenesis as well as the rupture of plaque. It possesses a broad substrate specificity and is the most active against type IV collagen, gelatin, elastin and the proteoglycan core proteins. The study hypothesized that the variation in base sequence within the promoter region of gelatinase B can alter its level. This alteration is capable of affecting the degradation of connective tissue during atherogenesis and the lesion progression. This can predispose the people carrying genetic variants to a more severe form of atherosclerosis.

Materials and Methods

In order to determine the activity of vascular NAD (P) H, Guzik et al. (2000) obtained the samples of human saphenous veins were from a total of 110 patients suffering from coronary artery disease and related risk factors. The expression of mRNA, p22phox and the allelic variants of 242C/T were indicated through three different methods. They include DNA sequencing, reverse transcription polymerase chain reaction and western immunoblotting. The production of both basal and NADH-driven superoxide was observed by the saphenous vein samples with the help of lucigenin-enhanced chemiluminescence (5 mmol/L lucigenin). The statistical analysis for the assessment of the differences in superoxide production included a Student’s t-test. The relationship between CYBA genotype and the superoxide production was analyzed using ANOVA.

Ishigami et al. (1995) included 82 patients suffering from coronary atherosclerosis and 160 control subjects in this study. All the subjects were Japanese and aged more than 30 years old. Each of the patients was suffering from at least one type of coronary artery with a luminal diameter obstruction greater than 25 percent. The blood samples from these subjects were collected in heparinized tubes and the white blood cells were separated. These peripheral blood leukocytes were used to extract the genomic DNA using the standard method involving proteinase K digestion of nuclei. The molecular variants of the angiotensinogen gene were designated as aa, Aa, and AA, where the a allele signified the thymine-cytosine transition in the nucleotide 704 of the exon 2. To amplify the specific regions of angiotensinogen gene, PCR was used and the restriction enzyme digestion was performed on the molecular variant of angiotensinogen gene, which was successfully identified.

Zhang et al. (1999) chose 25 to 64 years old males suffering from myocardial infarction to proceed the study and isolated Gelatinase B gene from them. PCR was used to sequentially amplify their promoter regions. They were amplified in the form of ≈450 base pair (bp) fragments. The products of PCR were digested with suitable restriction endonucleases to cleave amplicon into two fragments lying between 150 to 250 bp. Analysis for single-strand conformation polymorphism was performed on the digests in order to search for the promoter regions of the gene that encodes for gelatinase B

Results

DNA sequencing, Western immunoblotting, and reverse transcription PCR indicated that the