The contribution of extrapineal sites of melatonin synthesis to circulating melatonin levels in higher vertebrates

While the production of melatonin in higher vertebrates occurs in other organs and tissues besides the pineal, the contribution of extrapineal sites of melatonin synthesis such as the retina, the Harderian glands and the gut to circulating melatonin levels is still a matter of debate. The amount of melatonin found in the gastrointestinal tract is much higher than in any other organ including the pineal and the gut appears to make a significant contribution to circulating melatonin at least under certain conditions. The gut has been identified to be the major source of the elevated plasma concentrations of melatonin seen after tryptophan administration and of the changes of circulating melatonin level induced by the feeding regime. Whereas the circadian and circannual fluctuations of the concentration of melatonin in the blood seem to be triggered by changes of the photoenvironment and its effect of pineal melatonin formation, basal daytime melatonin levels and the extent of their elevation at nighttime appear to be additionally controlled by nutritional factors, such as the amount and the composition of ingested food and therefore availability of tryptophan as a rate-limiting precursor of melatonin formation by the enterochromaffin cells of the gastrointestinal tract.     

呼出气VOCs在上呼吸道感染病患与健康人间的异同

研究健康人与病患呼出气VOCs成分的异同, 为上呼吸道感染分型的无创快速诊断提供信息。采集60例上呼吸道感染患者、30例健康人呼出气, 利用GC-MS定量检测97种VOCs, 分析健康人及病患呼出气中烷烃、烯烃、卤代烃、含氧烃、芳香烃等物质的分布特点, 并利用ANOVA-PCA, 分析室内空气以及健康人和病患呼出气中VOCs的异同。结果表明, 异戊二烯浓度在病患、健康人呼出气及室内空气中均有显著差异(P<0.05), 且呈现病人>健康人>室内空气的特点; 正戊烷浓度在病患组显著高于健康人组(P<0.05); 丙醛浓度在细菌性上感组显著高于健康组(P=0.019)。PCA分析结果显示, 健康人与上呼吸道感染病患呼出气差异明显, 不同类型病患呼出气VOCs没有明显差异。     

温度和含水率对银中杨-玉簪落叶与草坪碎屑混料腐解的影响

用室内培养法对银中杨 玉簪落叶与草坪碎屑混料进行好氧腐解, 在不同温度和含水率下分析二者对混料腐解过程中水溶性物质、 可提取腐殖酸、 胡敏酸和胡敏素的碳质量比（WSOC, w_C(HE),w_C(HA),w_C(Hu)）、 胡敏酸（HA）碱溶液E₄/E₆及胡富比（w_C(HA)/w_C(FA)）的影响. 结果表明： 在混料腐解过程 中, 不同温度均可使HA分子结构在培养结束后趋于简单, C(Hu)可被有效矿化; 培养温度越高, w_C(HA)/w_C(FA)的降低程度越大;  在不同含水率下, C(Hu)均可有效矿化分解.     

家兔(Oryctolagus cunieulus Rabbits)消化道嗜银细胞的分布和形态学观察

本文应用Grimelius法对家兔（Oryctolagus cunieulus Rabbits)消化道嗜银细胞的形态、分布位置及分布密度进行了研究．实验结果显示：小肠段嗜银细胞呈梭形具有突起,而其它部位多数呈圆形或椭圆形;嗜银细胞多分布于粘膜上皮细胞之间或腺泡上皮之间;除食管未见嗜银细胞外,消化道其它部位均有嗜银细胞的分布,密度近似呈字母“M”形．根据其嗜银细胞形态,认为家兔消化道嗜银细胞具有内、外两种分泌方式．本文还结合家兔的食性、消化特点对嗜银细胞形态与功能相适应的特点进行了讨论．