论文部分内容阅读
背景:北方冬季日照时间短,婴幼儿易维生素D缺乏。最新教科书及中华医学会指南均认为玻璃遮挡紫外线,室内暴露对人类无意义。前期研究已经证明隔玻璃日光暴露对大鼠具有意义,但难以准确量化,且大鼠户外暴露难以继续进行。实验采用B波段紫外线,乃是日光中影响维生素D代谢的波长部分,且便于进一步深入研究。目的:观察实验室内中波紫外线对生长期大鼠血清25羟维生素D(25-hydroxy vitaminD,25-OHD)及骨代谢的影响。设计、时间及地点:采用随机同期对照动物实验,于2007-07在解放军总医院动物中心完成。材料:21d龄雄性Wistar大鼠40只。钙迪生人工光照补钙仪提供人工紫外线光源(波长280～350μm,照射强度5.5μW/cm2)。方法:将40只Wistar生长期大鼠用随机表随机分为4组,暴露于不同强度的紫外线下:直接照射组直接暴露20min,暴露剂量4.2mJ/(cm2·d);间接暴露60min组及120min组暴露通过普通玻璃分别照射60min及120min,暴露剂量0.36,0.72mJ/(cm2·d);非暴露组,无紫外线暴露。直接暴露组将人工光照补钙仪置于笼上,间接暴露组以厚度为3mm无色普通玻璃覆盖笼上,置于人工光照补钙仪下,暴露组为连续暴露,实验期20d。主要观察指标:第21天检测大鼠血清25-OHD、骨碱性磷酸酶(bone alkalinephos phatase,BALP)及骨密度(bone mineral density,BMD)。结果:各暴露组25-OHD显著高于非暴露组(P<0.001),但暴露组间无显著性差异。各暴露组BALP显著低于非暴露组(P<0.001),间接暴露组120min组BALP显著低于间接暴露60min组(P=0.022)。血清25-OHD及BALP间存在负相关(r=-0.569,P=0.002),但各组的BMD无统计学差异。暴露剂量与25-OHD存在正相关关系(r=0.555,P=0.002),暴露剂量与骨碱性磷酸酶间存在负相关关系(r=-0.595,P=0.001)但暴露剂量存在阈值现象,当0.36mJ/(cm2·d)达到后,血清25-OHD不再随暴露剂量增加而升高,BALP也不再随暴露剂量增加而下降。结论:中波紫外线通过玻璃照射引起生长期大鼠血清25(OH)D升高及BAP下降,且与直接暴露无明显差异。B波段紫外线暴露存在阈值现象,较小剂量并延长暴露时间,同样可以达到阈值暴露效果。
Background: Northern winter sunshine time is short, lack of vitamin D in infants and young children. The latest textbooks and guidelines from the Chinese Medical Association consider that glass blocks UV rays and that indoor exposure is not meaningful to humans. Previous studies have shown that glazing sunlight exposure in rats meaningful, but difficult to accurately quantify, and outdoor exposure in rats is difficult to continue. Experiments using B-band ultraviolet light, but the wavelength of sunlight affecting vitamin D metabolism, and facilitate further study. OBJECTIVE: To observe the effects of UVB on the serum 25-hydroxy vitamin D (25-OHD) and bone metabolism in the developing rats. DESIGN, TIME AND SETTING: A randomized controlled trial of synchronized animals was performed at the Animal Center of PLA General Hospital in 2007-07. MATERIALS: Forty-two male Wistar rats aged 21 days. Calcium Di Health artificial light calcium meter artificial UV light source (wavelength 280 ~ 350μm, irradiation intensity 5.5μW / cm2). Methods: Forty Wistar rats were randomly divided into 4 groups randomly. The rats were exposed to different intensities of UV light. The rats in the direct exposure group were exposed for 20 minutes and the exposure dose was 4.2 mJ / (cm2 · d) 120min exposure groups were exposed to ordinary glass 60min and 120min exposure, exposure dose 0.36,0.72mJ / (cm2 · d); non-exposed group, no UV exposure. Direct exposure group will artificial light calcium device placed in the cage, the indirect exposure group with a thickness of 3mm colorless ordinary glass covered cage, placed under artificial light calcium meter, exposure group for continuous exposure, the experimental period of 20d. MAIN OUTCOME MEASURES: On day 21, serum 25-OHD, bone alkaline phosphatase (BALP) and bone mineral density (BMD) were measured. Results: The 25-OHD in each exposed group was significantly higher than that in non-exposed group (P <0.001), but there was no significant difference between exposure groups. The BALP in each exposed group was significantly lower than that in non-exposed group (P <0.001). BALP in 120 min indirect exposure group was significantly lower than that in indirect exposure 60 min group (P = 0.022). There was a negative correlation between serum 25-OHD and BALP (r = -0.569, P = 0.002), but BMD in each group had no significant difference. There was a positive correlation between exposure dose and 25-OHD (r = 0.555, P = 0.002). The exposure dose had a negative correlation with bone alkaline phosphatase (r = -0.595, P = 0.001) When 0.36 mJ / (cm2 · d) reached, serum 25-OHD no longer increased with the increase of exposure dose, and BALP no longer decreased with the increase of exposure dose. CONCLUSION: The increase of serum 25 (OH) D and the decrease of BAP in the growing stage of rats exposed to UVB radiation have no significant difference with the direct exposure. B-band UV exposure there is a threshold phenomenon, smaller doses and extend the exposure time, the same threshold exposure can be achieved.