ABSTRACT
Objective To establish a reference range of cancellous bone ultrasonic backscatter coefficient (BSC) in term neonates,and to determine the significance of BSC in bone nutritional status in term newborns and infants.Methods Six hundred and sixty-five term newborns,who were born in Shanghai First Maternity and Infant Hospital from July 2014 to August 2014,were enrolled.On the third day and the 42nd day after birth,all infants underwent ultrasonic measurement of the calcaneum bone using a broadband-non-focus ultrasonic transducer at three frequencies (2.25,3.5 and 5 MHz).MATLAB software was used to analyze the backscatter signals.Clinical data of the infants,including gestational age,birth weight and birth age,were recorded at the same time.Statistical analyses of the data included variance analysis,Tukey's test,rank sum test,Dunn test and Pearson or Spearman correlation analysis.Results (1) Of the 665 infants,335 were male.The mean gestational age at birth was (38.0± 1.9) weeks,and the mean birth weight was (3 1524±226) g.(2) On the third day,there were significant differences in BSC values acquired at 2.25 and 3.5 MHz among the groups with different gestational ages or birth weights (2.25 MHz:H=9.842 and 17.271;3.5 MHz:H=6.275 and 21.450,respectively,all P＜0.05).At 3.5 and 2.25 MHz,BSC values were positively correlated with gestational age (r=0.047 and 0.035,respectively,both P＜0.05) and birth weight (r=0.125 and 0.186,both P＜0.05).(3) On the 42nd day,significant differences in BSC were observed at each frequency among the groups with different gestational ages or birth weights (gestational age:H=76.832,16.498 and 32.756;birth weight:H=70.014,18.095 and 34.126;all P＜0.01).Gestational age and birth weight were positively correlated with BSC value acquired at each frequency (r=0.397,0.286 and 0.272 for gestational age,0.451,0.223 and 0.196 for birth weight;all P＜0.01).Conclusions A preliminary BSC reference percentile in term-born infants is established.There are positive correlations between BSC value and newborn gestational age and birth weight at certain frequencies,which can reflect the status of the newborn's cancellous bone.Determination of BSC value should be performed during the follow-up period to assess the nutritional status of neonatal bone.
ABSTRACT
Objective To investigate the effect of persistent hypoglycemia on the cerebral oxidative stress and matrix metalloproteinase-2 (MMP-2) activity of newborn rats and to explore the potential mechanism of hypoglycemia-induced brain injury of newborn.MethodsSeven-day-old rats were injected insulin subcutaneously to induce persistent hypoglycemia.Cerebral cortex,hippocampus and thalamus were collected after 36 hours' observation and stored in -80 ℃.Glutathione (GSH)and glutathione disulfide (GSSG) were detected by commercial kit and GSSG/GSH was calculated.MMP-2 activity was detected by gelatin zymography. The data were analyzed by t test,one or two-wayanalysis of variance and Pearson correlation analysis.Six rats were set as the normal glucose group. ResultsThirty-six hours after induction of hypoglycemia, the cerebral GSSG and GSSG/GSH of hypoglycemic pups elevated about 1.5 times higher than those of control group [GSSG:(15.89 ± 5.46) vs (6.15 ± 3.42) mg/g protein,t =3.704,P =0.004; GSSG/GSH:(5.58± 1.79) ％ vs (2.79±1.76) ％,t =2.712,P=0.022].The GSSG and GSSG/GSH in thalamus of hypoglycemia were significantly higher than those of control [GSSG:(15.93 ± 5.75) mg/g protein vs (5.03±5.14)mg/g protein,P＜0.05; GSSG/GSH:(6.50±3.25) ％ vs (2.41±3.12) ％,P＜0.05],whereas there were no significant differences in the cortex ard hippocampus.The total MMP-2 activity of hypoglycemic animals (2.22±0.59) was significantly higher than that of control (1.21± 0.17)(t=4.064,P=0.002),and significant differences were found between the two groups in cortex (2.14 ± 0.5 vs 1.17± 0.27),hippocampus (2.31± 0.72 vs 1.22 ± 0.37) and thalamus (2.22±0.68 vs 1.24±0.18) with all P＜0.01].The activity of MMP-2 was positively related to GSSG (r=0.575,P=0.0002) and GSSG/GSH (r=0.484,P=0.0003).ConclusionsOxidative stress might play an important role in the persistent hypoglycemia induced brain injury of 7-day-old rat pups and thalamus might be most vulnerable to hypoglycemia.Hypoglycemia might also elevate MMP-2 activity which is positively related to GSSG level and GSSG/GSH of the brain.