[A comparative analysis of the efficacy of two vitamin D supplementation regimens in preterm infants: a prospective randomized controlled study].

OBJECTIVE: To study the effect of different vitamin D supplementation regimens on the nutritional status of vitamin D on day 28 after birth in preterm infants with a gestational age of <34 weeks. METHODS: A total of 59 preterm infants with a gestational age of <34 weeks who were born from October 2018 to October 2019 were enrolled and divided into an observation group with 30 infants and a control group with 29 infants. The infants in the observation group received a single-dose intramuscular injection of vitamin D3 (10 000 IU/kg), while those in the control group received oral vitamin D3 drops (900 IU/d) for 25 days. Venous blood samples were collected within 48 hours after birth (before vitamin D3 supplementation) and on day 28 after birth to measure the serum 25-hydroxyvitamin D [25(OH)D] level. RESULTS: Within 48 hours after birth, the prevalence rate of vitamin D deficiency (≤15 ng/mL) was 78% among the 59 preterm infants. There were no significant differences in the serum 25(OH)D level and the prevalence rate of vitamin D deficiency between the two groups (P>0.05). Compared with the control group on day 28 after birth, the observation group had a significantly higher serum 25(OH)D level (P<0.05) and a significantly lower prevalence rate of vitamin D deficiency (P<0.05). There were no cases of vitamin D overdose or poisoning. CONCLUSIONS: In preterm infants with a gestational age of <34 weeks, single-dose intramuscular injection of 10 000 IU/kg vitamin D3 can significantly increase serum 25(OH)D level on day 28 after birth and safely and effectively reduce the prevalence rate of vitamin D deficiency.

[Site-directed mutagenesis and protein expression of ABCA3 gene in A549 cells].

OBJECTIVE: To study the protocol of construction of the mutation E292V and M723I of hABCA3 gene associated with neonatal respiratory distress syndrome, as well as their eukaryotic green fluorescent protein expression rectors, and to examine the expression of mutation proteins in human lung carcinoma epithelial cells (A549). METHODS: Site-directed mutagenesis method based on overlap extension PCR was used to introduce mutations in the two sites which were E292V and M723I in the ABCA3. The PCR fragments were subcloned to PEGFP-C2 vectors to construct the eukaryotic green fluorescent protein expression rectors. A549 cells were transiently transfected with the recombinants using Lipofectamine 2000 and the transfection efficiency was confirmed through GFP signal. The expression and location of recombinants were detected by FV1000 laser scanning microscope. RESULTS: Direct sequence analysis confirmed an A to T transition at position 875 in E292V and a G to A transition at position 2169 in M723I. Recombinants were transfected to A549 cells and both wild type and mutant ABCA3 proteins were expressed in the cytoplasm. CONCLUSIONS: The eukaryotic green fluorescent protein expression rectors of wild type and mutant ABCA3 gene were constructed and they were successfully expressed in A549 cells. This experiment provides a basis for subsequent research.