几种因素在L-天冬酰胺酶化学修饰中对酶活力及抗原性的影响

为了寻求在较好地保持酶活力的同时解除L-天冬酰胺酶抗原性的方法,采用不同分子量的乙酸酐、右旋糖酐和单甲氧基聚乙二醇,作为修饰剂和不同的修饰方法对该酶进行了化学修饰。结果表明在保持酶活性和降低抗原性方面,大分子修饰剂右旋糖酐、单甲氧基聚乙二醇优于小分子乙酸酐,底物保护修饰优于直接修饰;活化PEG,优于活化PEG₁。在底物保护下的PEG,修饰酶其抗原性完全解除的同时,酶活力保持在30%以上。     

Endoscopic SIS injection into the lower oesophageal sphincter in dogs

Aim To determine the usefulness of endoscopically-delivered small intestinal submucosa (SIS) as a scaffold in enhancing the lower oesophageal sphincter (LOS) pressures. Methods Six dogs were endoscopically injected - four with the SIS and two with its glycerin carrier. Manometry was performed prior to injection and every four weeks post-op. Results Adequate and site correct injections were made in four dogs. In one dog, significant augmentation of pressures were obtained at four weeks. None had significant changes in pressure at eight weeks, differences in length at either four or eight weeks or significant differences in the thickness of the examined layers. Four of the six had capillary cushions on pathological examination. The dog injected with the carrier had a loose and disorganised collection, while the others were well organised. Conclusion SIS is a biologically compatible material. Lack of an animal model for gastro-oesophageal reflux disease (GORD) makes determining the ability of injections of SIS to combat reflux problematic.