| INTRODUCTIONAcute Myocardial infarction ( AMI) is a major health problem that has been associated with various risk factors, including hypertension, hyperlipidemia, diabetes mellitus, obesity and smoking. However , in some individuals, AMI is not associated with conventional risk factors, suggesting that other genetic factors are involved in the predisposition to coronary atherosclerosis and its thrombotic complications. Recent reports have suggested possible association of the Glu -298→ Asp(894 G → T) mutation at exon 7 of the endothelial nitric oxide synthesis gene and coronary artery disease.By methods of the polymerase chain reaction ( PCR) , and the PCR products are digested by restriction enzyme Ban E. In this stud-y, we can determine the frequency of mutation at exon 7 of eNOS in patients and controls and find the relation of a polymorphism of the eNOS with acute myocardial infarction.METHODSTwo groups: 107 patients with AMI and 59 healthy gender and age matched control subjects were selected, we got the genomic DNAfrom peripheral blood, synthesized the primer, then nested PCR, digested PCR products by restriction enzyme after amplification, detected by ultraviolet ray transmission analysis meter, counted the genotype and allele frequencies.RESULTSThree genotypes containing GG, GT, TT, were identified on the 894 site of the eNOS gene exon 7 in both AMI and controls. In AMI group, there were 25 patients who had homozygotes, the other 16 were heterozygotes. In controls, there were 8 cases who had G894T mutation, 0 homozygote, 8 heterozygotes. The mutation frequency of T/T homozygote allele extraordinary significant difference (p <0.01). For T/G heterozygotes between them, there was no significant difference (p>0.05).DISCUSSIONWith development of recent molecular biology, people are more and more attention with the association of genetic factors and disease. A report by Kiyoshi Hibi in 1998 showed an association between a polymorphism of the endothelial constitutive nitric oxide synthase gene and acute myocardial infarction, which cause people biggest interest.Three distinct isoforms of NOS have been identified to date, including neuronal NOS, inducible NOS and endothelial NOS. The endothelial NO synthase gene was assigned to the 7 q35 → 7 q36 region of chromosome 7 by Southern blot hybridization of human - rodent somatic cell hybrid lines and fluorescence in situ hybridization.The eNOS gene comprises 26 exons that span 21 kilo bases. NO is synthesized from the amino acid L - arginine by NO synthase. NO is an important endothelium - derived relaxing factor. It plays an important role in contributing the basal vascular tone and regulating blood flow and blood pressure. No can inhibit the proliferation of smooth muscle cells. Furthermore, NO can protect against platelet aggregation, and inhibit platelet adhesion to vascular endothelium. In addition, NO inhibits leukocyte adhesion to endothelium. NO diffuses from the endothelium to the vascular smooth muscle cells, where it increases the concentration of cGMP by stimulating soluble guanylate cy-clase, leading to vascular relaxation.Dysfunction of this important mechanism may promote destroy of vascular cells, atherogensis, platelet aggregation and problem of vascular relaxation and leading to high blood pressure and myocardial infarction.Our study focuses on the polymorphism of Glu - 298 - Asp at ex-on 7 of the endothelial nitric oxide synathase gene. Glu - 298 - The ammonia in Asp mutation leads to GAG at mRNA298 of eNOS encoding glutamic acid become GAT encoding aspartic acid, which affects construction of eNOS and causes decrease of acdvity of eNOS decrease of NO synthesized will promote platelets aggregation, increases stress of vascular and furthermore causes artery spasm . At present there are few study about polymorphism of the endothelial constitutive nitric oxide syntheses gene. But a few result of study is different. There is no report in china. We first conduct a case - control study to confirm associat...
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