Newman H A, Saat Y A, Hart R W
Environ Health Perspect. 1980 Feb;34:103-11. doi: 10.1289/ehp.8034103.
Syrian hamster embryo cells were treated with galactose oxidase, followed by reduction with tritiated sodium borohydride at pH 7.4. The labeling patterns of galactosyl and N-acetyl galactosaminyl residues on the cell surface were altered in comparing scraped vs. unscraped and buffer vs. media-soaked cells treated with galactose oxidase. From these preliminary studies, the procedure to be used in most of the asbestos treatment studies was to treat cells in situ, in buffer with galactose oxidase, and then to label treated scraped cells with NaB(3)H(4). After 20 hr interaction between chrysotile asbestos and Syrian hamster cell cultures, an alteration in surface labeling of glycolipids and glycoproteins was observed. Tritiated disialogangliosides (G(Dla)) and the higher molecular weight labeled glycoproteins were significantly reduced by asbestos treatment. Similar chrysotile asbestos-treated cultures were grown in monolayers in MEM (Eagles) with 10% fetal bovine serum for 2, 24, 48, and 72 hr and then surface-labeled with galactose oxidase-. NaB(3)H(4) in phosphate buffer. Little or no difference was observed between surface-labeled lipid or protein distribution in untreated cells and those treated with asbestos for 2 hr. Asbestos-induced polar and neutral glycolipid pattern changes were observed at 24, 48, and 72 hr. Disialo- and trisialogangliosides (the more complex gangliosides) were decreased 85%, whereas globoside GL-4 was decreased by 60% at 72 hr. An overall decrease of labeled glycoproteins was observed at 24-48 hr. By 72 hr there was a complete loss of labeled protein bands with 80,000 dalton molecular mass. Since the changes in glycoproteins and glycolipids occur only after extended exposure of the cells to asbestos, the present studies support the concept that a metabolic rather than immediate masking effect is involved. Comparisons of treatment of Syrian hamster embryo cells with various asbestos fibers for 48 hr in the order of decreasing reduction in complex gangliosides were crocidolite>chrysotile (intermediate)>amosite. Effects of the above fibers on high molecular weight glycoproteins labeling followed the same order. The labeling pattern is reminiscent of the increased simplification of glycolipids and glycoproteins found in transformed cells. In the case of asbestos which appears to have no independent mutagenic capability, it is more likely that the membrane changes induced by asbestos serve to allow other mutagens to pass into the cell so as to act on the nuclear structure.
用半乳糖氧化酶处理叙利亚仓鼠胚胎细胞，然后在pH 7.4条件下用氚化硼氢化钠还原。在比较刮取的细胞与未刮取的细胞以及用半乳糖氧化酶处理的缓冲液浸泡细胞与培养基浸泡细胞时，细胞表面半乳糖基和N - 乙酰半乳糖胺基残基的标记模式发生了改变。从这些初步研究中可知，大多数石棉处理研究中使用的方法是在缓冲液中用半乳糖氧化酶原位处理细胞，然后用NaB(3)H(4)标记处理过的刮取细胞。温石棉与叙利亚仓鼠细胞培养物相互作用20小时后，观察到糖脂和糖蛋白表面标记的改变。石棉处理使氚化双唾液酸神经节苷脂（G(Dla)）和更高分子量的标记糖蛋白显著减少。将类似的温石棉处理的培养物在含有10%胎牛血清的MEM（伊格尔氏）培养基中单层培养2、24、48和72小时，然后用磷酸缓冲液中的半乳糖氧化酶 - NaB(3)H(4)进行表面标记。在未处理的细胞和用石棉处理2小时的细胞之间，未观察到表面标记的脂质或蛋白质分布有明显差异。在24、48和72小时观察到石棉诱导的极性和中性糖脂模式变化。双唾液酸和三唾液酸神经节苷脂（更复杂的神经节苷脂）在72小时时减少了85%，而红细胞糖苷脂GL - 4减少了60%。在24 - 48小时观察到标记糖蛋白总体减少。到72小时时，分子量为80,000道尔顿的标记蛋白条带完全消失。由于糖蛋白和糖脂的变化仅在细胞长时间暴露于石棉后才发生，目前的研究支持这样一种概念，即涉及的是代谢而非即时的掩盖效应。按照复杂神经节苷脂减少程度由高到低的顺序，比较不同石棉纤维对叙利亚仓鼠胚胎细胞处理48小时的情况，结果是青石棉>温石棉（中等）>铁石棉。上述纤维对高分子量糖蛋白标记的影响遵循相同顺序。这种标记模式让人联想到在转化细胞中发现的糖脂和糖蛋白简化增加的情况。对于似乎没有独立诱变能力的石棉来说，更有可能的是石棉诱导的膜变化有助于使其他诱变剂进入细胞，从而作用于核结构。
