ObjectiveTo study the distribution characters and linkage disequilibrium of vitamin D receptor(VDR) gene ApaI and BsmI polymorphism,and explore the genetic susceptibility of VDR and vitamin D deficiency rickets.MethodsVDR gene ApaI and BsmI polymorphisms were determined by PCRRFLP technology in 56 cases of rickets and 76 cases of normal children.The frequencies of the VDR genotype and allele were compared between the two groups.The software SHEsis was used to make linkage disequilibrium analysis.Results No significant difference was found in either the frequency distribution of VDR gene ApaI and BsmI polymorphism or allele of them between two groups; Two polymorphisms didn't show linkage disequilibrium and D' and r2 were 0.23 and 0.01,respectively.ConclusionsThe ApaI and BsmI polymorphism of VDR gene might be not associated with vitamin D deficiency rickets.Two polymorphisms didn't show linkage disequilibrium.

Objective:To simulate the urinary tract environment in vitro and observe the local thermal effects generated by the holmium laser when it is continuously emitting under different mode settings, working medium and perfusion speed.Methods:This study was conducted from March to December 2019. Static medium model: Under normal pressure, 25℃ constant temperature and 50% humidity, a glass test tube with an inner diameter of 1cm and working medium of 1ml was placed into a beaker containing 300ml of 37℃ constant temperature water, and a 550 μm laser fiber was placed in the working medium in the test tube. The laser was continuously emitting for 60.0 seconds, and the temperature of the water in the test tube was continuously recorded using a temperature measuring instrument. The laser working mode was set as dusting, fragmenting, and "popcorn" mode, the energy was set at 10-20 W, and the working medium was normal saline, distilled water, and 5% mannitol solution. Flow medium model: In the same environment, the same optical fiber and temperature probe were placed in a 6mm flush tube, and the laser was continuously fired and continuously perfused with saline. The flushing speed was controlled between 100 ml/h and 1 200 ml/h, and the water temperature change during laser emission was recorded. The real-time temperature changes around the fiber tip with different modes, different media, and different perfusion rates were analyzed.Results:Static medium model: After the holmium laser was continuously fired for about 6.0±1.2 seconds, it exceeded the safe temperature of 43℃ , reached the plateau temperature in about 27.6±2.1 seconds and drop to the safe temperature after stopping excitation for 38.2±2.4 seconds. The plateau temperature dusting group > "popcorn" group > fragmenting group ( P<0.01), of which the dusting group(78.67±0.45)℃ (20 W) was the highest and the fragmenting group (55.67±0.22)℃ (10 W) was the lowest. The temperature of 5% mannitol solution (73.92 ± 0.44) ℃ was the lowest among the three experimental working media, which was (75.57±0.14)℃ of distilled water group and (78.67±0.45)℃ of normal saline group (0.4 J×50 Hz, 20 W). Flow medium model: The perfusion rate of 800ml/h can ensure that the continuous emitting of the holmium laser remains at a safe temperature (40.96±0.36)℃. It only took 7.0±1.0 seconds to decrease to the initial temperature after stopping emittion. Conclusions:Under the same total power, the high-energy-low-frequency fragmenting lithotripsy mode has a relatively lower thermal effect. Under the same total power, the thermal effect of holmium laser emittion is relatively lower in the environment of 5% mannitol solution. Perfusion of ≥800ml/h can effectively reduce the local high temperature caused by the thermal effect of holmium laser.

Objective:To investigate the effects of breast milk to total milk intake ratio during hospitalization on the duration of antibiotic therapy in preterm infants less than 34 weeks of gestation.Methods:Clinical data of preterm infants ( n=1 792) less than 34 gestational weeks were retrospectively collected in 16 hospitals of Jiangsu Province Neonatal-Perinatal Cooperation Network from January 1, 2019, to December 31, 2021. The days of therapy (DOT) were used to evaluate the duration of antibiotic administration. The median DOT was 15.0 d (7.0-27.0 d). The patients were divided into four groups based on the quartiles of DOT: Q 1 (DOT≤7.0 d), Q 2 (7.0 d27.0 d) groups. According to the breast milk intake ratio (breast milk intake to total milk intake during hospitalization×100%), they were also divided into four groups: very-low-ratio breastfeeding group (breast milk intake ratio≤25%), low-ratio breastfeeding group (25%75%). Univariate analysis ( Chi-square test and Kruskal-Wallis rank-sum test) was used to analyze the factors influencing DOT. Spearman correlation analysis and trend Chi-square test were used to explore the relationship between breast milk intake ratio and DOT. After using multiple imputations to address missing data, two models were constructed after adjusting for different factors, and multinomial logistic regression model was applied to evaluate the effects of the breast milk intake ratio on DOT. Finally, sensitivity analysis was conducted to assess the stability of the models. Results:(1) Of the 1 792 preterm infants, there were 507 (28.3%) in the Q 1 group, 422 (23.5%) in the Q 2 group, 438 (24.4%) in the Q 3 group and 425 (23.7%) in the Q 4 group. (2) The median values of DOT in the very-low-ratio, low-ratio, medium-ratio and high-ratio breastfeeding groups were 20.0 d (11.0-31.0 d), 20.0 d (11.0-32.0 d), 13.0 d (6.0-25.8 d) and 10.0 d (4.0-21.0 d), respectively. Compared with the very-low-ratio and low-ratio breastfeeding groups, the medium-ratio and high-ratio breastfeeding groups had shorter DOT (all P<0.05). (3) After adjusting for factors with P<0.1 (prenatal glucocorticoid exposure, antimicrobial use within 24 h before delivery, gestational age at delivery, birth weight, Apgar score≤7 at 1 min, neonatal respiratory distress syndrome, infectious pneumonia and early-onset neonatal sepsis) between the DOT quartile groups, it showed that medium-ratio and high-ratio breastfeeding were protective factors in contrast to very-low-ratio breastfeeding in the Q 2, Q 3 and Q 4 groups as compared with the Q 1 group [Q 2 group: OR=0.50 (95% CI: 0.30-0.85) and OR=0.36 (95% CI: 0.26-0.51); Q 3 group: OR=0.31 (95% CI: 0.18-0.55) and OR=0.20 (95% CI: 0.14-0.29); Q 4 group: OR=0.22 (95% CI: 0.12-0.42) and OR=0.17 (95% CI: 0.12-0.26)]. Conclusion:Breast milk intake accounting for over 50% of total milk intake has a positive impact on reducing DOT in premature infants requiring antibiotics, which suggests that breastfeeding should be actively encouraged.