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目的探讨汉族与维吾尔族儿童封闭型不同龋敏感中变形链球菌乳酸脱氢酶活性与ldh基因多态性及龋病发生的关系。方法从前期实验分离的维吾尔族与汉族儿童口腔变形链球菌中筛选出:维吾尔族儿童封闭型口腔变形链球菌高龋组变形链球菌35株[龋失补牙数(dmft)≥5],无龋组变形链球菌37株[龋失补牙数(dmft)=0];27株表现乳酸脱氢酶高活性,24株低活性;汉族儿童口腔中分离的高龋和无龋变形链球菌各35株,高活性和低活性各25株,使用特异引物扩增细菌组DNA,获得结构基因ldh,进行聚合酶链反应-限制性内切酶多态性分析。结果维吾尔族儿童封闭型和汉族儿童MseⅠ酶切ldh-RFLP表现A、B两种基因型;而MnlⅠ、DdeⅠ、NlaⅢ和AluⅠ消化扩增产物未发现多态性。MseⅠ产生的B基因型菌株在维吾尔族儿童封闭型,汉族儿童高龋组的检出均高于无龋组(P<0.05),A、B两种基因型在不同酶活性组的分布不同(P<0.05),高酶活性组B基因型菌株的比例高于低酶活性组;A、B基因型在维吾尔族儿童封闭型和汉族高龋组、无龋组,高酶活性组和低酶活性组的检出比较差异无统计学意义(P>0.05)。结论变形链球菌乳酸脱氢酶基因多态性在维吾尔族与汉族儿童并未表现出差异性,ldh基因多态性与变形链球菌乳酸脱氢酶活性及龋高敏感性相关。ldh基因分布与酶活性及乳牙龋具有正相关性。
Objective To investigate the relationship between lactate dehydrogenase (LDH) activity, ldh gene polymorphism and dental caries in Streptococcus mutans of Han and Uygur children with different caries susceptibility. Methods: 35 strains of Streptococcus mutans of Uighur children with oral Dental Streptococcus mutans were selected from Uighur and Han children oral mutans ([dmft ≥5], caries-free Group 37 Streptococcus mutans [dental caries loss teeth (dmft = 0]; 27 showed high activity of lactate dehydrogenase, 24 low activity; isolated from the oral cavity of Han children 35 caries and caries-free Streptococcus mutans , 25 with high activity and low activity. The specific primers were used to amplify the bacterial DNA to obtain the structural gene ldh. Polymerase chain reaction-restriction endonuclease polymorphism analysis was performed. Results Both genotypes A and B were digested with MseⅠ in Mü Ⅰ -type and Han-children in Uygur children. No genotypes were found in MnlⅠ, DdeⅠ, NlaⅢ and AluⅠ digesting products. The genotypes of B genotypes produced by MseⅠwere higher in carious Uighur children and in caries-bearing children of Han children than those in caries-free caries group (P <0.05). The genotypes A and B were different in different enzyme activities P <0.05). The proportion of genotype B strains in high enzyme activity group was higher than that in low enzyme activity group. The genotypes A and B were not significantly different between Uighur children with closed caries and Han caries group, caries-free group, There was no significant difference in the active group (P> 0.05). Conclusion The polymorphism of lactate dehydrogenase gene of Streptococcus mutans was not different between Uygur and Han children. The polymorphism of ldh gene was correlated with lactate dehydrogenase activity and caries hypersensitivity of Streptococcus mutans. ldh gene distribution and enzyme activity and deciduous teeth have a positive correlation.