Meenan J, O'Hallinan E, Lynch S, Molloy A, McPartlan J, Scott J, Weir D G
Department of Clinical Medicine, Trinity College and St James's Hospital, Dublin.
Gut. 1996 Mar;38(3):410-3. doi: 10.1136/gut.38.3.410.
Localised folate deficiency has been implicated in colonic carcinogenesis and supplementation has been proposed for certain populations at risk. However, identifying those groups that may benefit is difficult as the relation between blood folate and gut epithelial cell values is unknown. The aim of this study was to define this relation. Epithelial cells mean (SEM) (sigmoid: 5.35 (0.56) x 10(6) cells, caecum: 6.6 (0.71) x 10(6) cells, duodenum: 4.0 (0.62) x 10(6) cells) were isolated from four endoscopic mucosal biopsy specimens (n = 25) by incubation with dithiothreitol (three hours) and EDTA (one hour). Lamina propria contamination was < 1%, with < 6% intraepithelial lymphocytes. Folate assay of isolates showed sigmoid colon folate content to be 20.1 (1.8) pg/micrograms DNA (10.2-46.6). In the same subject, caecal folate concentrations were lower (p < 0.01, n = 11) than sigmoid values, whereas duodenal isolates mirrored those of the sigmoid (19.4 (2.9) v 20.5 (3.2), n = 5). Sigmoid folate values were consistent over one to three weeks (n = 3). In a single case with blood folate deficiency, colonic values were normal. Serum folate and red cell folate correlated poorly with sigmoid epithelial cell folate content (r = 0.41, p = 0.063 and r = 0.17, p > 0.05 respectively). This study reports a modified ion-chelation isolation method for colonic biopsy specimens that yields large numbers of viable epithelial cells. Cell folate values remain constant with time though vary with intestinal region. The inability of serum or red cell folate values to predict those of the sigmoid epithelium suggests that they cannot identify those patients that might benefit from folate supplements.
局部叶酸缺乏与结肠癌发生有关，有人提议对某些高危人群进行补充。然而，由于血液叶酸与肠道上皮细胞值之间的关系尚不清楚，很难确定哪些人群可能受益。本研究的目的是明确这种关系。通过与二硫苏糖醇（3小时）和乙二胺四乙酸（1小时）孵育，从4份内镜黏膜活检标本（n = 25）中分离出上皮细胞均值（标准误）（乙状结肠：5.35（0.56）×10⁶个细胞，盲肠：6.6（0.71）×10⁶个细胞，十二指肠：4.0（0.62）×10⁶个细胞）。固有层污染<1%，上皮内淋巴细胞<6%。分离物的叶酸测定显示，乙状结肠叶酸含量为20.1（1.8）pg/μg DNA（10.2 - 46.6）。在同一受试者中，盲肠叶酸浓度低于乙状结肠（p < 0.01，n = 11），而十二指肠分离物与乙状结肠相似（19.4（2.9）对20.5（3.2），n = 5）。乙状结肠叶酸值在1至3周内保持一致（n = 3）。在1例血液叶酸缺乏的病例中，结肠值正常。血清叶酸和红细胞叶酸与乙状结肠上皮细胞叶酸含量的相关性较差（r = 0.41，p = 0.063和r = 0.17，p > 0.05）。本研究报告了一种改良的离子螯合分离方法，用于结肠活检标本，可产生大量活的上皮细胞。细胞叶酸值随时间保持恒定，但因肠道区域而异。血清或红细胞叶酸值无法预测乙状结肠上皮细胞的叶酸值，这表明它们无法识别那些可能从叶酸补充剂中受益的患者。
