Becher R, Sandberg A A
Hum Genet. 1983;63(4):358-61. doi: 10.1007/BF00274762.
Central and peripheral sister chromatid exchanges (SCE) were evaluated separately in human phytohemagglutinin (PHA)-stimulated lymphocytes after culture for 72 h in 5-bromodeoxyuridine (BrdU) containing medium. At the same time, the length of chromosome No. 1 was measured in 10 metaphases per case and the mean value taken as a representative parameter for the contraction of chromosomes. The statistical analysis of regression revealed a close relationship between the percentage of SCE observed in the centromere and the contraction state of chromosomes (P less than or equal to 0.01). A statistically significant increase of central exchanges was seen in more condensed chromosomes, due to the difficulty in differentiating clearly between centric and pericentric exchanges. Consequently, if exchanges in the centromere are omitted from evaluation, this would lead to spuriously low SCE rates in more contracted chromosomes. In order to exclude the variable factor of chromosome contraction in SCE studies, we highly recommend inclusion of counts of central exchanges. Results obtained on chromosomes with twisted chromatids, a situation which tends to stimulate SCE, should be omitted.
在含5-溴脱氧尿苷（BrdU）的培养基中培养72小时后，分别评估人植物血凝素（PHA）刺激的淋巴细胞中的中央和外周姐妹染色单体交换（SCE）。同时，测量每个病例10个中期相中1号染色体的长度，并将平均值作为染色体收缩的代表性参数。回归统计分析显示，在着丝粒处观察到的SCE百分比与染色体的收缩状态之间存在密切关系（P≤0.01）。由于难以清晰区分着丝粒交换和近着丝粒交换，在更浓缩的染色体中观察到中央交换有统计学上的显著增加。因此，如果在评估中忽略着丝粒处的交换，这将导致在收缩程度更高的染色体中SCE率出现假性降低。为了在SCE研究中排除染色体收缩这一可变因素，我们强烈建议纳入中央交换的计数。对于具有扭曲染色单体的染色体（这种情况往往会刺激SCE）所获得的结果应予以排除。
