Comar D, Saudubray J M, Duthilleul A, Delforge J, Maziere M, Berger G, Charpentier C, Todd-Pokropek A
Eur J Pediatr. 1981 Mar;136(1):13-9. doi: 10.1007/BF00441705.
The brain uptake of 11C-methionine was studied in 26 children with classical phenylketonuria; one adult was used as a control. Labelled methionine uptake in brain was first measured during a low phenylalanine diet and again one week later after a load of phenylalanine. Ten children aged 1 to 30 months were studied twice at intervals of several months. In children having a phenylalaninemia less than or equal to 0.3 mumoles . ml-1, a decrease in methionine brain uptake was observed with increasing age, with the largest change occurring during the first year of life. After the phenylalanine load, a mean increase in phenylalaninemia by a factor of ten was accompanied by a mean decrease in brain methionine uptake by a factor of two while blood methionine remained unchanged. Brain activity curves increased with time for children younger than one year and having phenylalaninemia less than 0.6 mumoles . ml-1. After the age of 2 most patients had a decreasing curve regardless of the blood phenylalanine level. This study indicates that 11C-methionine brain uptake may be taken as an index of blood barrier permeability to essential amino acids, and of brain maturation. The results obtained suggest that an increase in phenylalaninemia to levels greater than 0.6 mumole . ml-1 induces a modification in brain uptake of amino acids, primarily during the first two years of life.
对26名经典型苯丙酮尿症患儿的大脑摄取¹¹C-蛋氨酸情况进行了研究，以1名成人作为对照。首先在低苯丙氨酸饮食期间测量大脑中标记蛋氨酸的摄取情况，一周后在给予苯丙氨酸负荷后再次测量。对10名年龄在1至30个月的儿童每隔几个月进行了两次研究。在苯丙氨酸血症小于或等于0.3微摩尔·毫升⁻¹的儿童中，观察到蛋氨酸大脑摄取量随年龄增长而减少，最大变化发生在生命的第一年。给予苯丙氨酸负荷后，苯丙氨酸血症平均增加了10倍，同时大脑蛋氨酸摄取量平均减少了一半，而血液中的蛋氨酸保持不变。对于年龄小于1岁且苯丙氨酸血症小于0.6微摩尔·毫升⁻¹的儿童，大脑活性曲线随时间增加。2岁以后，大多数患者的曲线下降，无论血液苯丙氨酸水平如何。这项研究表明，¹¹C-蛋氨酸大脑摄取量可作为血脑屏障对必需氨基酸通透性以及大脑成熟度的指标。所得结果表明，苯丙氨酸血症增加至大于0.6微摩尔·毫升⁻¹的水平会引起大脑对氨基酸摄取的改变，主要发生在生命的头两年。
