Possible involvement of active oxygen species on the patients with homocystinuria and the infants with respiratory distress syndrome

1)同型半胱氨酸尿：同型半胱氨酸尿是一种先天性的蛋氨酸代谢错误，其特征是过早发展为动脉硬化。低密度脂蛋白（LDL）作为动脉硬化发病的主要因素之一，其修饰已受到众多研究者的广泛关注。在本研究中，为了阐明同型半胱氨酸水平升高与过早动脉硬化之间的关系，我们研究了同型半胱氨酸在铁催化的LDL氧化修饰中的作用。同型半胱氨酸与铁培养时，巯基含量逐渐减少，并逐渐形成超氧化物和亚铁离子。该反应形成硫代巴比妥酸反应物质（TBARS）和荧光物质，并发生载脂蛋白B（apo-B）的断裂。氧化修饰的程度取决于同型半胱氨酸的浓度。低密度脂蛋白的修饰被抑制，直到α -生育酚消耗达到临界水平。当LDL中α -生育酚含量增加2.6倍时，TBARS的形成和载脂蛋白b的破碎均受到一定程度的抑制。这些结果表明，同型半胱氨酸可能促进铁催化的LDL氧化，内源性α -生育酚可以保护LDL免受氧化修饰。呼吸窘迫综合征：我们测量了11例有呼吸窘迫综合征（RDS）和11例无呼吸窘迫综合征（非RDS）早产儿的血浆尿尿浓度，作为自由基生成的建议标志物。出生后3 ~ 12小时RDS婴儿血浆尿囊素水平显著高于非RDS婴儿，但出生后3小时内两组尿囊素水平无显著差异。这些观察结果表明，RDS婴儿的血浆水相中确实产生了一些氧化剂，尿囊素的测量可能是新生儿自由基参与的有用指标。少

1).Homocystinuria : Homocystinuria is an inborn error of methionine metabolism that is characterized by the premature development of arteriosclerosis. As one of the major factors in the pathogenesis of arteriosclerosis, modification of low-density lipoprotein (LDL) has received widespread attention by many investigators. In this study, to elucidate the relationship between elevated homocysteine levels and premature arteriosclerosis, we investigated the role of homocysteine in the iron-catalyzed oxidative modification of LDL.When we incubated homocysteine with ferric iron, the content of sulfhydryl groups gradually decreased, and both superoxide and ferrous ion formed gradually. In this reaction thiobarbituric acid-reactive substances (TBARS) and fluorescent substances were formed, and the fragmentation of apoprotein B(apo-B) occured. The extent of oxidative modification was dependent on the concentration of homocysteine. Modification of LDL was suppressed until alpha-tocopherol consump … More tion reached a critical level. When the alpha-tocopherol content of LDL was increased 2.6 fold, both the formation of TBARS and the fragmentation of apo-B were suppressed to some extent. These results suggest that homocysteine might promote iron-catalyzed oxidation of LDL, and endogenous alpha-tocopherol can protect LDL against oxidative modification.2).Respiratory distress syndrome : We measured plasma allantion concentration as a proposal marker for free radical generation in 11 premature infants with respiratory distress syndrome (RDS) and 11 without RDS (non-RDS). Plasma allantoin level in RDS infants between 3 and 12 hours of life was significantly higher than that in non-RDS infants, although no significant difference was found in two groups within 3 hours after birth. These observation suggests that some oxidants are acturelly generated in the aqueous phase of plasma in RDS infants and the measurement of allantoin may be a useful indicator for free radical involvement in neonates. Less