Wu Y, Chen J, Ohshima H, Pignatelli B, Boreham J, Li J, Campbell T C, Peto R, Bartsch H
Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Beijing.
Int J Cancer. 1993 Jul 9;54(5):713-9. doi: 10.1002/ijc.2910540502.
Overnight urine samples were collected from approximately 60 male adults in each of 69 counties of China in 1989. Two specimens were collected from each subject--one after a loading dose of proline and ascorbic acid and another after a loading dose of proline only. Levels of N-nitrosamino acids and nitrate were measured in urine samples and correlated with cumulative mortality rates for subjects aged between 0 and 64 years in the 1970s. Oesophageal cancer mortality rates were positively and significantly associated with (i) urinary levels of excreted N-nitrosoproline (NPRO) (after proline and ascorbic acid loading or proline loading only), (ii) N-nitrososarcosine levels, and (iii) nitrosation potential (the decrease in the amount of urinary NPRO after adding ascorbic acid to the proline load). There were also positive correlations between the urinary level of NPRO or other N-nitrosamino acids and that of nitrate. The urinary excretion of nitrate was associated with consumption of various nitrate-rich vegetables. The results suggest that N-nitroso compounds (NOC) or other nitrite-derived carcinogens are implicated in the aetiology of oesophageal cancer in China.
1989年，在中国69个县中，从约60名成年男性中收集过夜尿液样本。每个受试者收集两份样本——一份在给予脯氨酸和抗坏血酸负荷剂量后采集，另一份仅在给予脯氨酸负荷剂量后采集。测量尿液样本中N-亚硝基氨基酸和硝酸盐的水平，并将其与20世纪70年代0至64岁受试者的累积死亡率相关联。食管癌死亡率与以下因素呈正相关且具有显著相关性：（i）排泄的N-亚硝基脯氨酸（NPRO）的尿液水平（在给予脯氨酸和抗坏血酸负荷剂量后或仅给予脯氨酸负荷剂量后），（ii）N-亚硝基肌氨酸水平，以及（iii）亚硝化潜力（在脯氨酸负荷剂量中添加抗坏血酸后尿液中NPRO量的减少）。NPRO或其他N-亚硝基氨基酸的尿液水平与硝酸盐的尿液水平之间也存在正相关。硝酸盐的尿液排泄与各种富含硝酸盐蔬菜的摄入量有关。结果表明，N-亚硝基化合物（NOC）或其他亚硝酸盐衍生的致癌物与中国食管癌的病因有关。
