Asami T, Nakano T, Sakai K
Rinsho Byori. 1989 Sep;37(9):1051-5.
We studied isozymes of urinary beta-D-N-acetylglucosaminidase (NAG), NAG-A and NAG-B, to develop a method for the determination of them. Urinary NAG-A was demonstrated to be measured most appropriately by the thermal inactivation at 50 degrees C for 4 hours in the buffer solution of pH 4.8. Using this method, 13 subjects were simultaneously measured for the levels of both urinary and serum NAG-A, which revealed no significant relation between them (r = 0.03). A significant increase in the mean value of urinary NAG-A activities (U/ml) was found in the 11-12 year-old subjects compared with those in the 6-7 year-old subjects. Although no significant differences were revealed among the total urinary NAG activities of the subjects, the values of NAG-A/total NAG (percent) tended to increase as the ages of the subjects increasing. In conclusion, when determining urinary NAG levels, a careful consideration must be taken into account for the presence of heterozygous carriers for Tay-Sachs disease who have a 50%-deficiency of NAG-A activity and for the age difference of the values.
我们研究了尿β-D-N-乙酰氨基葡萄糖苷酶（NAG）的同工酶NAG-A和NAG-B，以开发一种测定它们的方法。结果表明，在pH 4.8的缓冲溶液中于50℃热灭活4小时，最适合测定尿NAG-A。使用该方法，对13名受试者同时测定了尿和血清中NAG-A的水平，结果显示二者之间无显著相关性（r = 0.03）。与6-7岁的受试者相比，11-12岁的受试者尿NAG-A活性（U/ml）的平均值显著升高。虽然受试者的总尿NAG活性之间未显示出显著差异，但NAG-A/总NAG（百分比）的值倾向于随着受试者年龄的增加而升高。总之，在测定尿NAG水平时，必须仔细考虑患有NAG-A活性50%缺乏的泰-萨克斯病杂合子携带者的存在以及数值的年龄差异。
