Dingley K H, Roberts M L, Velsko C A, Turteltaub K W
Biology and Biotechnology Research Program and Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94551-9900, USA.
Chem Res Toxicol. 1998 Oct;11(10):1217-22. doi: 10.1021/tx9801458.
This is the first demonstration of the use of accelerator mass spectrometry (AMS) as a tool for the measurement of 3H with attomole (10(-18) mol) sensitivity in a biological study. AMS is an analytical technique for quantifying rare isotopes with high sensitivity and precision and has been most commonly used to measure 14C in both the geosciences and more recently in biomedical research. AMS measurement of serially diluted samples containing a 3H-labeled tracer showed a strong correlation with liquid scintillation counting. The mean coefficient of variation of 3H AMS based upon the analysis of separately prepared aliquots of these samples was 12%. The sensitivity for 3H detection in tissue, protein, and DNA was approximately 2-4 amol/mg of sample. This high sensitivity is comparable to detection limits for 14C-labeled carcinogens using 14C AMS and demonstrates the feasibility of 3H AMS for biomedical studies. One application of this technique is in low-dose, dual-isotope studies in conjunction with 14C AMS. We measured the levels of 3H-labeled 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 14C-labeled 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) in rat liver tissue and bound to liver DNA and protein 4.5 h following acute administration of individual or coadministered doses in the range of 4-5100 pmol/kg of body weight. Levels of PhIP and MeIQx in whole tissue and bound to liver protein were dose-dependent. MeIQx-protein and -DNA adduct levels were higher than PhIP adduct levels, which is consistent with their respective carcinogenicity in this organ. Coadministration of PhIP and MeIQx did not demonstrate any measurable synergistic effects compared to administration of these compounds individually. These studies demonstrate the application of AMS for the low-level detection of 3H in small biological samples and for its use in conjunction with 14C AMS for dual-labeling studies.
这是首次证明在生物学研究中使用加速器质谱法（AMS）作为一种工具来测量具有阿托摩尔（10⁻¹⁸摩尔）灵敏度的³H。AMS是一种用于高灵敏度和高精度定量稀有同位素的分析技术，最常用于地球科学领域测量¹⁴C，最近也用于生物医学研究。对含有³H标记示踪剂的系列稀释样品进行AMS测量，结果显示与液体闪烁计数法有很强的相关性。基于对这些样品单独制备的等分试样的分析，³H AMS的平均变异系数为12%。在组织、蛋白质和DNA中检测³H的灵敏度约为2 - 4阿托摩尔/毫克样品。这种高灵敏度与使用¹⁴C AMS检测¹⁴C标记致癌物的检测限相当，证明了³H AMS用于生物医学研究的可行性。该技术的一个应用是与¹⁴C AMS结合用于低剂量双同位素研究。我们在急性给予大鼠个体或联合给予体重范围为4 - 5100皮摩尔/千克的剂量后4.5小时，测量了大鼠肝脏组织中以及与肝脏DNA和蛋白质结合的³H标记的2 - 氨基 - 1 - 甲基 - 6 - 苯基咪唑并[4,5 - b]吡啶（PhIP）和¹⁴C标记的2 - 氨基 - 3,8 - 二甲基咪唑并[4,5 - f]喹喔啉（MeIQx）的水平。全组织中PhIP和MeIQx以及与肝脏蛋白质结合的水平呈剂量依赖性。MeIQx与蛋白质和DNA的加合物水平高于PhIP加合物水平，这与它们在该器官中的各自致癌性一致。与单独给予这些化合物相比，联合给予PhIP和MeIQx未显示出任何可测量的协同效应。这些研究证明了AMS在小生物样品中低水平检测³H以及与¹⁴C AMS结合用于双标记研究的应用。
