Mock D M
Department of Pediatrics, University of Iowa, Iowa City 52242.
J Pediatr Gastroenterol Nutr. 1990 Feb;10(2):222-9. doi: 10.1097/00005176-199002000-00013.
Abnormalities in fatty acid composition have been detected in biotin deficiency in humans and in the rat. However, the pathogenetic role of these abnormalities, if any, in the cutaneous manifestations of biotin deficiency is not clear. In a nutrient interaction experiment, we tested the hypothesis that an abnormality of omega 6 polyunsaturated fatty acid (PUFA) metabolism plays a pathogenetic role in the cutaneous manifestations. Five rats were fed an egg white diet that induces biotin deficiency; these rats developed the characteristic cutaneous abnormalities of biotin deficiency. Five additional rats were pair-fed the egg white diet and received Liposyn [77% linoleic acid (18:2 omega 6)]; these rats did not develop the cutaneous manifestations of biotin deficiency. The two groups had similar decreases in the rates of urinary excretion of biotin, the serum concentrations of biotin, the amounts of biotin in liver, and the hepatic activities of two biotin-dependent carboxylases; the two groups had similar increases in the rates of urinary excretion of 3-hydroxyisovaleric acid. These observations provide evidence that (a) some abnormality in omega 6 PUFA metabolism has a pathogenetic role in the cutaneous manifestations of biotin deficiency and (b) this pathogenetic role can not be explained as a difference in biotin nutritional status due to a biotin-sparing effect of Liposyn.
在人类和大鼠的生物素缺乏症中已检测到脂肪酸组成异常。然而，这些异常（如果存在的话）在生物素缺乏症皮肤表现中的致病作用尚不清楚。在一项营养相互作用实验中，我们检验了以下假设：ω-6多不饱和脂肪酸（PUFA）代谢异常在皮肤表现中起致病作用。给5只大鼠喂食诱导生物素缺乏的蛋清饮食；这些大鼠出现了生物素缺乏的特征性皮肤异常。另外5只大鼠与上述大鼠配对喂食蛋清饮食，并给予Liposyn[77%亚油酸（18:2 ω-6）]；这些大鼠未出现生物素缺乏的皮肤表现。两组大鼠的生物素尿排泄率、血清生物素浓度、肝脏生物素含量以及两种生物素依赖性羧化酶的肝脏活性均有相似程度的降低；两组大鼠的3-羟基异戊酸尿排泄率均有相似程度的升高。这些观察结果证明：（a）ω-6 PUFA代谢的某些异常在生物素缺乏症的皮肤表现中起致病作用；（b）这种致病作用不能解释为由于Liposyn的生物素节省效应导致生物素营养状况的差异。
