Martin R S, Small D M
J Lab Clin Med. 1984 May;103(5):798-810.
The aim of this study was to investigate the nature of urinary lipid in humans with nephrotic syndrome. Fresh urine specimens were fractionated by centrifugation into a lower cellular fraction and an upper noncellular fraction. Of the 11 urine specimens examined, six cellular fractions contained cells (oval fat bodies) that were laden with anisotropic (birefringent) droplets when viewed by polarizing microscopy. The mean total cholesterol excretions for the five urine specimens without anisotropic droplets and the six urine specimens with anisotropic droplets were 8.7 mg/L and 35.5 mg/L, respectively. The cellular fractions of the six urine specimens with anisotropic droplets are enriched in cholesterol esters relative to whole urine. Upon heating, the anisotropic droplets underwent phase transitions characteristic of cholesterol esters, as observed by polarizing microscopy. The mean cholesteric to isotropic phase transition temperature of the anisotropic droplets was 41.3 degrees C. These data indicate that the anisotropic droplets of the oval fat bodies were composed of cholesterol esters acylated largely with monounsaturated fatty acids consistent with cellular origin. The noncellular fractions were subjected to ultracentrifugation (48,000 X g for 2 hours) and then separated into supernate and infranate fractions. The supernate fractions contained minor amounts of lipid, except in two cases of massive lipiduria. In these two cases, the supernate fractions contained many individual anisotropic droplets with lipid composition nearly identical to their cellular fractions. The dispersed lipid of the infranate fractions were invisible by microscope. Nine of the 11 infranate fractions revealed an alpha migrating lipid band by agarose gel electrophoresis. For urine specimens with anisotropic droplets, the infranate fractions contained cholesterol ester fatty acids that were less saturated (as measured by gas-liquid chromatography) than the cellular fractions. Thus, the cholesterol esters of the infranate fractions were derived from a different source (probably high-density lipoproteins) than the cholesterol esters of the cellular fractions.
本研究的目的是调查肾病综合征患者尿脂质的性质。新鲜尿液标本通过离心分离为下层细胞部分和上层无细胞部分。在检查的11份尿液标本中，6个细胞部分含有细胞（椭圆形脂肪体），在偏光显微镜下观察时，这些细胞充满各向异性（双折射）液滴。5份无各向异性液滴的尿液标本和6份有各向异性液滴的尿液标本的平均总胆固醇排泄量分别为8.7mg/L和35.5mg/L。6份有各向异性液滴的尿液标本的细胞部分相对于全尿富含胆固醇酯。加热后，通过偏光显微镜观察，各向异性液滴经历了胆固醇酯特有的相变。各向异性液滴的平均胆甾相到各向同性相转变温度为41.3℃。这些数据表明，椭圆形脂肪体的各向异性液滴由主要用单不饱和脂肪酸酰化的胆固醇酯组成，与细胞来源一致。无细胞部分进行超速离心（48,000×g，2小时），然后分离为上清液和沉淀部分。上清液部分除了2例大量脂质尿外，仅含有少量脂质。在这2例中，上清液部分含有许多单个各向异性液滴，其脂质组成与其细胞部分几乎相同。沉淀部分的分散脂质在显微镜下不可见。11份沉淀部分中的9份通过琼脂糖凝胶电泳显示出α迁移脂质带。对于有各向异性液滴的尿液标本，沉淀部分所含胆固醇酯脂肪酸的饱和度（通过气液色谱法测定）低于细胞部分。因此，沉淀部分的胆固醇酯与细胞部分的胆固醇酯来源不同（可能来自高密度脂蛋白）。
