脐血铅浓度与新生儿端粒长度的相关性

脐血铅浓度与新生儿端粒长度的相关性 摘要 目的 研究脐血铅浓度与新生儿端粒长度的相关性。 方法 收集2010年7月2013年4月青岛市市立医院产科孕期无急慢性疾病的足月顺产儿脐血78例，原子吸收光谱法测定脐血铅浓度，测得脐血铅浓度在1189?g/L范围。将78例脐血分成A、B、C三组：A组脐血铅浓度60?g/L，共12例。采用全血提取基因组法提取脐血DNA，荧光定量PCR法测基因组DNA的端粒长度。各组间比较采用单因素方差分析，两两比较采用q检验，相关性采用Spearman相关性研究。 结果 A组端粒长度为：1.1520.716，B组端粒长度为0.6140.407，C组端粒长度为0.5460.339，从A组到C组端粒长度逐渐缩短，且差异有统计学意义（F=4.895，P0.05）。三组端粒长度与脐血铅浓度呈负相关（r=-0.461，P0.01）。 结论 脐血铅可导致新生儿端粒长度的缩短，且随脐血铅浓度的升高，新生儿端粒长度进行性缩短，端粒长度缩短影响细胞分裂，决定细胞寿命。 关键词 脐血；铅；新生儿；端粒长度 中图分类号 R743.3 文献标识码 A 文章编号 2095-0616（2014）06-07-05 A correlation study of umbilical cord blood lead concentrations and neonatal telomere length ZHAO Yanfang QU Baoming LIU Wendong MA Haiyan Department of Paediatrics，Affiliated Qingdao Municipal Hospital of Qingdao University Medical College，Qingdao 266000，China Abstract Objective To study the correlation of umbilical cord blood lead concentrations and neonatal telomere length. Methods We collected 78 cases of umbilical cord blood from term infants whose gestation was without acute or chronic disease from Qingdao Municipal Hospital between July of 2010 to April of 2013.We used atomic absorption spectrometry to determine the concentration of umbilical cord blood lead. The umbilical cord blood lead concentrations measured range was between 11 and 89 ?g/L. The 78 cases of umbilical cord blood was divided into three groups：A，B，and C.Umbilical cord blood lead concentrations for group A was 60 ?g/L （n=12）.To extract umbilical cord blood DNA，extraction genome DNA from whole blood was used. Fluorescence quantitative PCR was used to measure the telomere length of genome DNA.Data were assessed by one-way analysis of variance，differences between groups were compared by q-test and the relationship were analyzed with Spearman correlation research. Results The telomere length of group A was 1.1520.716，the telomere length of group B was 0.6140.407，and the telomere length of group C was 0.5460.339.The telomere length shortened gradually from group A to group C，and the difference was statistically significant（F=4.895，P0.05）.The relationship of the three groups telomere length and umbilical cord blood lead concentrations correlated negatively（r=-0.461，P Reverse primer，5-GGCTTGCCTTACCCTTACCCTTACCCTTACCCTTACCCT-3；primer sequences of 36B4 gene was： Forward primer，5-CAGCAAGTGGGAAGGTGTAATCC-3；Reverse primer，5-CCCATTCTATCATCAACGGGTACAA-3. Cycling conditions （for both telomere and 36B4）were：10min at 95，followed by 40 cycles of 95，for 5s， 56for 30s，and 72 for 60s. 1.2.2 Make standard curve and calculate telomere length Select one sample to dilute （dilution factor is five） according to the ratio of equality as the standard preparation， they were： 0.016ug/L，0.08ug/L， 4ug/L，20ug/L，and 100ug/L. Then got Ct value by PCR，and according to Ct value of standard preparation and itsconcentration to make standard curve.Last，reckon the telomere length by the Ct value.The calculation formula of telomere length was：telomere length=2-Ct，Ct=Ctstandard preparation-Ctexample，Ctexample=Ct36B4-Cttelomere，Ctstandard preparation =Ct36B4-Cttelomere. 1.3 Statistics analysis SPSS17.0 was used to make one-factor analysis of variance between groups by the relative telomere length and different umbilical cord blood lead concentrations.The differences between groups were compared by q-test.Spearman correlation research can be used to analyze the relationship between umbilical cord blood lead and telomere length. 2 Results 2.1 Standard curve and molten curve Nonspecific products did not be found in melting curve appears（figure 2）. Figure 1 Telomere standard curve Temperature， Celsius Temperature， Celsius Figure 2 Molten curve of telomere and 36B4 2.2 Concentration of umbilical cord blood lead Group A cord blood lead concentrations 60 ?g/L，a total of 12 cases. 2.3 Average telomere length The telomere length of group A was 1.1520.716，the telomere length group B was 0.6140.407，and the telomere length group C was 0.5460.339.The telomere length shortened gradually from group A to group C and the difference showed statistical significance（F=4.895，P 2.4 The relationship of telomere length and blood lead concentration The relationship between telomere length and blood lead concentration was a negative correlation （r=-0.461， P100?g/L.Lead does not have any normal physiological functions in the human body，but lead can affect a variety of system functions and is not easily removed after it enters the body. Without any normal physiological functions to in human body，its ideal blood lead concentrations should be 0. As a result， some developed countries lowered the lower limit defining concentration for lead poisoning，setting the blood lead concentrations 60?g/L as lead poisoning. For the fetus，lead is mainly transferred by the mother during pregnancy through the umbilical cord and placental barrier.Therefore，this study collected umbilical cord blood and different of umbilical cord blood lead concentrations were divided into three groups： group A cord blood lead concentrations 60?g/L. This allowed us to study the effect of umbilical cord blood lead to neonatal telomere length.From these result we determined that with the rise of umbilical cord blood lead concentration，the telomere length shorten progressively，and telomere length and umbilical cord blood lead concentrations correlated negatively（r=-0.461，P 30 ?g/L， telomere length would seriously be affected and cause telomere shortening.The latest study suggested that the two main factors19for telomere shortening were the incomplete copy of cell division telomere end and the damage of telomere DNA. Under normal condition， these two factors could be recover telomere length under the action of telomere and the binding of telomerase and telomere protein. But when there was lead exposure， telomere shortening could not be restored， telomerase and telomere binding protein function was affected by lead and caused the telomere length shortening. Accordingly we conclude，umbilical cord blood lead can shorten the neonatal telomere length；with increasing blood lead concentration，the telomere length of neonate are progressively shortened；and lead may be interfere with telomere length and make it short by influencing the role of telomerase and telomere binding protein. In summary，umbilical cord blood lead can shorten the length of neonatal telomere and different neonatal umbilical cord blood lead concentrations are associated with different changes to telomere length. When umbilical cord blood lead exceeds 30?g/L，the newborn telomere length will be affected seriously， and the higher the concentration，the more serious the impact on neonatal telomere length. The length of the telomere shortening can also increase the incidence of a number of diseases，such as Coronary Heart Disease，Hypertension，Cancer，Diabetes，Obstructive Sleep Apnea Syndrome， and a variety of autoimmune diseases.It also can affect childrens mental development.Therefore，we should pay more attention to the influence of maternal lead exposure during pregnancy on neonatal growth and development.The influence of blood lead on telomere length may be by affected telomerase and telomere binding protein function that makes the telomere length shortened， however the exact mechanism remains to be further studied. 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