[Risk factors for metabolic bone disease of prematurity in very/extremely low birth weight infants: a multicenter investigation in China].

OBJECTIVE: To investigate the incidence rate and risk factors for metabolic bone disease of prematurity (MBDP) in very low birth weight/extremely low birth weight (VLBW/ELBW) infants. METHODS: The medical data of 61 786 neonates from multiple centers of China between September 1, 2013 and August 31, 2016 were retrospectively investigated, including 504 VLBW/ELBW preterm infants who met the inclusion criteria. Among the 504 infants, 108 infants diagnosed with MBDP were enrolled as the MBDP group and the remaining 396 infants were enrolled as the non-MBDP group. The two groups were compared in terms of general information of mothers and preterm infants, major diseases during hospitalization, nutritional support strategies, and other treatment conditions. The multivariate logistic regression analysis was used to investigate the risk factors for MBDP. RESULTS: The incidence rate of MBDP was 19.4% (88/452) in VLBW preterm infants and 38.5% (20/52) in ELBW preterm infants. The incidence rate of MBDP was 21.7% in preterm infants with a gestational age of < 32 weeks and 45.5% in those with a gestational age of < 28 weeks. The univariate analysis showed that compared with the non-MBDP group, the MBDP group had significantly lower gestational age and birth weight, a significantly longer length of hospital stay, and a significantly higher incidence rate of extrauterine growth retardation (P < 0.05). Compared with the non-MBDP group, the MBDP group had significantly higher incidence rates of neonatal sepsis, anemia, hypocalcemia, and retinopathy of prematurity (P < 0.05). The MBDP group had a significantly lower mean feeding speed, a significantly higher age when reaching total enteral feeding, and a significantly longer duration of parenteral nutrition (P < 0.05). The use rate of caffeine citrate in the MBDP group was significantly higher, but the use rate of erythropoietin was significantly lower than that in the non-MBDP group (P < 0.05). The multivariate logistic regression analysis showed that gestational age < 32 weeks, hypocalcemia, extrauterine growth retardation at discharge, and neonatal sepsis were risk factors for MBDP (P < 0.05). CONCLUSIONS: A lower gestational age, hypocalcemia, extrauterine growth retardation at discharge, and neonatal sepsis may be associated an increased risk of MBDP in VLBW/ELBW preterm infants. It is necessary to strengthen perinatal healthcare, avoid premature delivery, improve the awareness of the prevention and treatment of MBDP among neonatal pediatricians, and adopt positive and reasonable nutrition strategies and comprehensive management measures for preterm infants.

[Relationship between serum adiponectin and bone mineral density in preterm infants].

OBJECTIVE: To examine serum adiponectin level in preterm infants and to evaluate the relationship between serum adiponectin and bone mineral density in preterm infants. METHODS: Seventy-two appropriate-for-gestational-age neonates were classified into three groups according to their gestational ages: early preterm (31-33(+6) weeks, 13 cases), late preterm (34-36(+6) weeks, 16 cases), and full-term (37-42 weeks, 43 cases). Venous blood was collected at one week of their life to measure serum adiponectin concentration. During the period, omnisense ultrasound bone sonometer was applied to measure speed of sound (SOS) of the left tibia. RESULTS: The median of tibia SOS in the early preterm group was significantly lower than in the late preterm and full term groups (P<0.05), and the median of tibia SOS in the late preterm group was lower than in the full-term group (P<0.05). Serum adiponectin level was lowest in the early preterm group, and the full-term group had the highest serum adiponectin level. Serum adiponectin level was positively correlated with tibia SOS in preterm infants (r=0.664, P<0.05). According to the result of multivariate linear stepwise regression analysis, serum adiponectin and birth weight were independent predictor of tibia SOS in preterm infants. CONCLUSIONS: Serum adiponectin level is lower in preterm infants than that in full-term infants. There is a positive correlation between serum adiponectin and bone mineral density in preterm infants.

[Effects of L-Arg on expression of PI3K and PKB in liver among low-birth-weight newborn rats].

OBJECTIVE: To measure the expression of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB) in liver tissue among low-birth-weight newborn rats treated with L-arginine (L-Arg) in early life, and to investigate the effect of L-Arg on insulin resistance. METHODS: Eighteen pregnant rats were randomly divided into three groups: control, model and intervention (n=6 each). The control group was fed with normal protein feed (protein content=21%) during pregnancy to establish a normal-birth-weight newborn rat model, and the model and intervention groups were fed with low-protein feed (protein content=10%) during pregnancy to establish a low-birth-weight newborn rat model. Newborn rats from the three pregnant rat groups were also assigned to control, model and intervention groups. During 21 days of lactation, maternal rats in the control and model groups were fed with normal protein feed and normal drinking water, while maternal rats in the intervention group were fed with normal protein feed and drinking water rich in L-Arg (200 mg/kg·d). After ablactation, the three groups of newborn rats were fed with normal protein feed and normal drinking water. Liver tissue samples were collected from these newborn rats at 1, 3 and 8 weeks after birth. Protein expression of PI3K and PKB in liver tissue was measured by Western blot. RESULTS: At 1 week after birth, the newborn rats in the intervention group had significantly higher protein expression of PI3K than in the model group (P=0.045), but there was no significant difference when compared with the control group (P=0.503). At 8 weeks after birth, the newborn rats in the intervention group had significantly higher protein expression of PKB than the model group (P=0.039), but there was no significant difference when compared with the control group (P>0.05). CONCLUSIONS: A supplement of L-Arg in early life can boost protein synthesis, increase protein expression of PI3K and PKB in liver tissue, promote insulin signaling and reduce insulin resistance.