[Early postnatal application of glucocorticoids for preventing bronchopulmonary dysplasia in preterm infants: a Meta analysis].

OBJECTIVE: To study the clinical effect and safety of early postnatal application of glucocorticoids in the prevention of bronchopulmonary dysplasia (BPD) in preterm infants. METHODS: The databases including PubMed, Cochrane Library, Embase, CNKI, Wanfang Data, and VIP were comprehensively searched for articles on early postnatal application of glucocorticoids in the prevention of BPD in preterm infants published up to June 2016. Review Manager 5.3 was used for the Meta analysis of 16 randomized controlled trials (RCTs) that met the inclusion criteria. RESULTS: A total of 2 962 participants were enrolled in the 16 RCTs, with 1 486 patients in the trial group and 1 476 in the control group. The Meta analysis showed that early postnatal application of glucocorticoids reduced the incidence rate of BPD at a corrected gestational age of 36 weeks (OR=0.73, 95%CI: 0.61-0.87, P=0.0004), but there was an increase in the risk of hyperglycemia (OR=1.61, 95%CI: 1.24-2.09, P=0.0003), hypertension (OR=1.63, 95%CI: 1.11-2.38, P=0.01), and intestinal perforation (OR=1.51, 95%CI: 1.12-2.04, P=0.007). CONCLUSIONS: At present, it is not recommended to use glucocorticoids to prevent BPD in preterm infants. Its advantages and disadvantages need further studies, with special focuses on the adverse effects of hyperglycemia, hypertension, and intestinal perforation.

[Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.