Kazmierczak S C, Robertson A F
Department of Pathology, East Carolina University School of Medicine, Greenville, NC 27858-4354.
Ann Clin Lab Sci. 1992 May-Jun;22(3):155-61.
Diamine oxidase (DAO) is an enzyme synthesized primarily in the gastrointestinal mucosal cells. Serum levels of DAO have been used as an indicator of the integrity and/or functional mass of the intestinal mucosa. The enzyme is also produced by the placenta and is elevated in newborn serum. Previous radiometric methods for DAO used tritiated putrescine or cadaverine as substrate. A simple and rapid spectrophotometric procedure for DAO with use of histamine as substrate was developed, and this assay was utilized to evaluate the developmental pattern of activity of DAO in umbilical cord blood of newborn full-term and premature infants, in sequential samples from premature infants, and in samples from infants with necrotizing enterocolitis. The spectrophotometric assay was linear to 200 U per L and was also precise with total imprecision (CV) of 11.9 percent and 3.7 percent at DAO activities of 25.6 U per 1 and 126.1 U per L, respectively. Triglycerides above 275 mg per dL caused a significant reduction in measured activity of DAO; however, this effect could be eliminated by use of ultracentrifugation to remove lipemia. Plasma samples with heparin or ethylenediamine tetraacetic acid (EDTA) as anticoagulant were unsuitable for analysis since DAO activity showed a 24 percent and 32 percent decrease in activity at concentrations of 20 U per mL (heparin) and two mg per mL (EDTA), respectively. Serum samples are the specimen of choice. In infants it was found that the serum activity declined to adult levels by day 12 of life and that this decline is not affected by necrotizing arterocolitis.
二胺氧化酶（DAO）是一种主要在胃肠道黏膜细胞中合成的酶。血清DAO水平已被用作肠道黏膜完整性和/或功能质量的指标。该酶也由胎盘产生，在新生儿血清中升高。以前用于DAO的放射性方法使用氚标记的腐胺或尸胺作为底物。开发了一种使用组胺作为底物的简单快速的DAO分光光度法，该测定法用于评估足月和早产新生儿脐带血中DAO活性的发育模式、早产儿的连续样本以及坏死性小肠结肠炎婴儿的样本。分光光度法在每升200 U范围内呈线性，在DAO活性分别为每升25.6 U和126.1 U时，总不精密度（CV）分别为11.9%和3.7%，也很精确。甘油三酯水平高于每分升275毫克会导致DAO的测量活性显著降低；然而，这种影响可以通过使用超速离心去除脂血来消除。以肝素或乙二胺四乙酸（EDTA）作为抗凝剂的血浆样本不适合分析，因为在每毫升20 U（肝素）和每毫升2毫克（EDTA）的浓度下，DAO活性分别降低了24%和32%。血清样本是首选的标本。在婴儿中发现，血清活性在出生后第12天降至成人水平，并且这种下降不受坏死性动脉结肠炎的影响。
