谷氨酰胺和丙氨酰-谷氨酰胺双肽影响人回结肠粘膜增殖的离体实验

背景/目的谷氨酰胺(Gln)对危重患者小肠上皮有一定营养作用。在肠外营养时由于其不够稳定而限制了它的应用,但此不足可通过使用稳定的丙氨酰-谷氨酰胺双肽(Ala-Gln)而克服。本研究目的是验证如下假设,即谷氨酰胺或丙氨酰-谷氨酰胺双肽不但可以刺激回肠细胞增殖,而且可以刺激结肠细胞增殖,维护肠屏障功能。方法将正常人回肠、近段结肠、乙状结肠及直肠活检标本分别加入谷氨酰胺(2mmol/L)、丙氨酰-谷氨酰胺双肽(2mmol/L)、生理盐水(对照),孵育4小时。S期的细胞用5溴-2脱氧尿苷标记。对被标记的腺管纵向切片和静止期细胞进行记数。结果谷氨酰氨和丙氨酰-谷氨酰胺双肽可以刺激回肠细胞、近段结肠、乙状结肠及直肠腺管细胞的增殖。在回肠标本,整个腺管的细胞均被较好的标记,而在结肠则主要对腺管的基底部分有营养作用。结论谷氨酰胺或丙氨酰-谷氨酰胺双肽不但对回肠细胞,而且对结肠细胞有营养作用,从而可阻止肠外营养时肠粘膜萎缩,维护肠屏障功能。

Advances in Water Quality Monitoring of Inorganics: Current Trends

New methods of analysis for water quality monitoring to detect inorganic substances are required to meet the demands of determining concentration, particularly at low detection limits, analysing speciation and even identifying the pollution source. Such information is essential to inform public health decisions and to comply with more stringent legislation. This paper concentrates on two case studies, reviewing the development in monitoring methods, and predicting future trends. Arsenic and nitrates detection was selected as these pollutants are particularly problematic from a human health perspective. Additionally, the challenges faced in developing monitoring methods for these chemicals are relevant to a wide range of other inorganics. The current state of the art in detection approaches for these chemicals are discussed along with recommendations for future research to further improve the methods.