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Objective@#To compare bioelectrical impedance analysis (BIA) and dual energy X ray absorptiometry (DXA) for measuring body mineral content (BMC) of children and adolescents, and to provide a basis for BIA to accurately measure BMC in children and adolescents.@*Methods@#By using the convenience sampling method, among 1 469 children and adolescents aged 7-17 were recruited in Guangzhou from April to May 2019, the BMC was measured by DXA and BIA. The intraclass correlation coefficient ( ICC ) and Bland Altman analysis were used to evaluate the agreement between BIA and DXA. Bland Altman analysis was performed on log transformed data. The BMC was categorized into age and specific tertiles, and the agreement between methods was evaluated based on the kappa coefficients. Treating the BMC with DXA as the dependent variable, a prediction model was constructed for correcting the BIA measure.@*Results@#The ICC s were 0.93 and 0.94 for boys and girls, respectively. In Bland Altman analysis, the limits of agreements for the BIA to DXA ratio were wide in boys and girls, ranging from 0.27-0.76 and 0.17-0.72, respectively. The kappa coefficients for categorized BMC levels were 0.57 and 0.45 for boys and girls, respectively, showing a fair to good degree of agreement. When sub grouped by BMI, the kappa coefficients for all BMI groups of boys and overweight girls were all >0.75 , with an excellent agreement. The prediction models for boys and girls were as follows: BMC DXA =-0.51+0.44× BMC BIA + 0.06× Age +0.02× BMI ; and BMC DXA =-0.55+0.43× BMC BIA +0.06× Age +0.02× BMI , respectively. The R 2 for models of boys and girls were 0.87 and 0.87, respectively.@*Conclusion@#The agreement between BIA and DXA was poor for measuring BMC, but acceptable when evaluating the categorized BMC levels, suggesting the BIA may be applied in assessment of the BMC levels when compared to the age and gender specific population. Additionally, the prediction model for correcting BMC by BIA fis well to the measurement by DXA.
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Objective@#To explore the influence of birthweight and delivery mode on overweight/obesity and abdominal obesity in primary school students, and to provide evidence for childhood obesity prevention.@*Methods@#After physical examination, questionnaire survey was conducted among 3 361 students and their parents from 3 primary schools in Guangzhou selected through stratified clustering sampling. Information about birthweight and delivery mode was collected. Logistic regression model was used to analyze the association of birthweight and delivery mode with overweight/obesity and abdominal obesity. The multiplicative interaction term and the Delta method was used to explore the potential interaction.@*Results@#The prevalence rate of overweight and obesity for primary school students was 21.33%, and the rate of abdominal obesity was 12.08%. Multivariate Logistic regression analysis showed that delivery by cesarean section was associated with 44% increased risk of overweight/obesity(OR=1.44, 95%CI=1.16-1.80), as compared to vaginal delivery. Higher birthweight was linked to increased risk of overweight/obesity(OR=1.62, 95%CI=1.09-2.42). There was no significant association of birth weight and delivery mode with abdominal obesity in multivariate analysis(P>0.05). Additionally, a positive additive interaction was seen between delivery mode and parental obesity for students risk of overweight/obesity(RERI=0.33, 95%CI=0.02-0.65), as well as for the risk of abdominal obesity(RERI=0.39, 95%CI=0.12-0.65).@*Conclusion@#Cesarean section delivery and higher birthweight are linked to increased risk of overweight and obesity in primary school students. The synergistic effect of cesarean section and parental obesity may increase the risk of childhood obesity.
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Objective@#To investigate the effect of maternal passive smoking during pregnancy and girls’ overweight /obesity on the age at menarche(AAM), and to provide a reference for improving healthy development of children and adolescents.@*Methods@#Based on the school entrance physical examination in 2016, a cross-section study was conducted by convenient sampling method, in a total of 2 722 students of 7th grade, from 26 middle schools in urban areas of Guangzhou. Multivariate logistic regression model was used to investigate the relationship between maternal passive smoking during pregnancy and girls’ overweight /obesity and AAM. A four-way decomposition method was used to explore the mediated effect of girls’ overweight/obesity on the relationship between maternal passive smoking during pregnancy and AAM.@*Results@#The proportion of girls who had menstruate was 90.82%(2 472/2 722). The median AAM was 12.00 years old, with an early menarche rate of 34.91%(863/2 472). Compared with girls whose mother hadn’t passive smoking during pregnancy, the risk of early AAM in girls with mother passive smoking during pregnancy≤3 days/week increased by 32%(OR=1.32, 95%CI=1.06-1.65), the risk in girls with maternal passive smoking during pregnancy>3 days/week increased by 58%(OR=1.58, 95%CI=1.21-2.07). Multivariate Logistic regression analysis showed that, overweight or obesity girls had a 77% higher risk of early AAM than non-overweight/obesity girls(OR=1.77, 95%CI=1.36-2.31). The four-way decomposition analysis showed 79.60% of early AAM risk could be accounted by maternal passive smoking during pregnancy(P<0.01).@*Conclusion@#Girls’ overweight/obesity and maternal passive smoking during pregnancy were associated with early menarche. The effect on daughters’ age at menarche is mainly in a direct effect manner of maternal passive smoking during pregnancy.
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<p><b>OBJECTIVE</b>To construct esat6-ppe68 fusion gene and its prokaryotic expression vector for expression in E. coli.</p><p><b>METHODS</b>With GeneSOEing method, a fusion gene was constructed by splicing esat6 gene and ppe68 gene and cloned into pGEX-4T-1 plasmid to construct the recombinant prokaryotic expression plasmid pGesat6-ppe68. After identification with restriction enzyme analysis, PCR and nucleotide sequencing analysis of the plasmid, E. coli BL21 was transformed with the recombinant plasmid and induced with IPTG to obtain the expression of the fusion protein ESAT6-PPE68 with GST-tag (about 69 kD), which were purified with GST-fusion protein purification kit. The expression of esat6-ppe68 fusion gene was subsequently detected by SDS-PAGE and Western blot analysis.</p><p><b>RESULTS</b>The sequence of esat6 and ppe68 in the recombinant plasmid was consistent with that in GenBank report. The fusion protein was detected in the cytoplasm in soluble form and represented approximately 40% of the total bacterial protein of E. coli. After purification, the purity of the fusion protein reached 90%, and its antigenicity was confirmed by Western blotting.</p><p><b>CONCLUSION</b>The prokaryotic expression vector pGesat6-ppe68 has been constructed and the fusion protein ESAT6-PPE68 obtained successfully, which provides an experimental basis for potential application of the recombinant ESAT6-PPE68 in the diagnosis of tuberculosis.</p>