Determination of N-nitrosamines in gastric juice and urine and a comparison of endogenous formation of N-nitrosoproline and its inhibition in subjects from high- and low-risk areas for oesophageal cancer.
Samples of gastric juice were collected from a high-risk area for oesophageal cancer in China and analysed for N-nitroso compounds. N-Nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosomethylbenzylamine (NMBzA), N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP) were identified in descending order of concentration. Several unknown compounds were also detected in the fasting gastric juice. A positive correlation was found between the amount of nitrosamines in gastric juice and the degree of severity of lesions of the oesophageal epithelium: the amounts of nitrosamines in gastric juice from subjects with a normal oesophageal epithelium were lower than those in subjects with marked dysplasia or carcinoma of the oesophagus. In addition, 1500 samples of 24-h urine were collected from various communes in six high-risk areas and two low-risk areas for this cancer in China and analysed for N-nitrosamino acids. Subjects in high-risk areas excreted higher levels than those in low-risk areas. Intake of L-proline resulted in marked increases in levels of urinary N-nitrosoproline (NPRO) in inhabitants from both high- and low-risk areas. Intake of moderate doses of vitamin C, alpha-tocopherol and zinc by high-risk subjects reduced the urinary levels of N-nitrosamino acids to those found in undosed subjects in low-risk areas, suggesting a rational basis for prevention in high-risk areas.
Lu
S H
SH
Cancer Institute, Chinese Academy of Medical Sciences, Beijing.
Yang
W X
WX
Guo
L P
LP
Li
F M
FM
Wang
G J
GJ
Zhang
J S
JS
Li
P Z
PZ
D002681:China; D004052:Diethylnitrosamine / Q000032:analysis; D004128:Dimethylnitrosamine / Q000032:analysis; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000378:metabolism; D005750:Gastric Juice / Q000032:analysis*; D006801:Humans; D009602:Nitrosamines / Q000032:analysis* / Q000378:metabolism* / Q000652:urine; D012307:Risk Factors
D009602:Nitrosamines; D004052:Diethylnitrosamine; C010259:nitrosoproline; D004128:Dimethylnitrosamine