Urinary levels of N-nitroso compounds in relation to risk of gastric cancer: Findings from the Shanghai cohort study

Background: N-Nitroso compounds are thought to play a significant role in the development of gastric cancer. Epidemiological data, however, are sparse in examining the associations between biomarkers of exposure to N-nitroso compounds and the risk of gastric cancer. Methods: A nested case-control study within a prospective cohort of 18,244 middle-aged and older men in Shanghai, China, was conducted to examine the association between urinary level of N-nitroso compounds and risk of gastric cancer. Information on demographics, usual dietary intake, and use of alcohol and tobacco was collected through in-person interviews at enrollment. Urinary levels of nitrate, nitrite, N-nitroso-2-methylthiazolidine-4-carboxylic acid (NMTCA), N-nitrosoproline (NPRO), N-nitrososarcosine (NSAR), N-nitrosothiazolidine-4-carboxylic acid (NTCA), as well as serum H. pylori antibodies were quantified in 191 gastric cancer cases and 569 individually matched controls. Logistic regression method was used to assess the association between urinary levels of N-nitroso compounds and risk of gastric cancer. Results: Compared with controls, gastric cancer patients had overall comparable levels of urinary nitrate, nitrite, and N-nitroso compounds. Among individuals seronegative for antibodies to H. pylori, elevated levels of urinary nitrate were associated with increased risk of gastric cancer. The multivariate-adjusted odds ratios for the second and third tertiles of nitrate were 3.27 (95% confidence interval = 0.76-14.04) and 4.82 (95% confidence interval = 1.05-22.17), respectively, compared with the lowest tertile (P for trend = 0.042). There was no statistically significant association between urinary levels of nitrite or N-nitroso compounds and risk of gastric cancer. Urinary NMTCA level was significantly associated with consumption of alcohol and preserved meat and fish food items. Conclusion: The present study demonstrates that exposure to nitrate, a precursor of N-nitroso compounds, may increase the risk of gastric cancer among individuals without a history of H. pylori infection

Proba zbadania wplywu dodatku jonow magnezowych na zmiany poziomu azotanow i azotynow w wybranych kiszonkach warzywnych

Sprawdzono oddziaływanie jonów magnezowych na aktywność reduktazy azotanowej kapusty głowiastej białej, a następnie zbadano ich wpływ na zmiany poziomu azotanów i azotynów w niektórych kiszonkach warzywnych. Uzyskane wyniki badań wykazały, że jony magnezowe powodowały istotny wzrost aktywności reduktazy azotanowej, a dodatek w odpowiednich ilościach chlorku magnezu do surowca w czasie przygotowywania do kiszenia spowodował istotny spadek zarówno poziomu azotanów jak i azotynów.The aim of this study was to examine the effect of magnesium ions on some changes in the nitrate reductase activity in the white headed cabbage as well as a practical application of the results obtained in vegetable souring. As experimental material were used: white and red headed cabbage, red beets and the same vegetable in the soured form. Vegetable souring was performed using a traditional method as well as a modified one, considiering a supplement of magnesium chloride at various levels during the process of souring. The activity of nitrate reductase in the white headed cabbage was determined by the Jaworski method. In raw and soured vegetables the level of nitrates was determined by brucine method and that of nitrites by the Griess colorimetric method. A supplement of magnesium ions to the incubation mixture containing raw white cabbage resulted in an increased activity of the studied enzyme by 17,0-34,8% and was significant in all magnesium ions concetrations used. The introduction of adequate amounts of magnesium chloride to soured vegetable production resulted also in a significant decrease in the nitrate and nitrite levels. An organoleptic evaluation of soured vegetables made by a traditional method and by using a supplement high quality, although the smell of white headed cabbage and "beet acid" has slightly however, significantly deteriorated

An attempt to investigate the effect of magnesium ions and vitamin C on the activity of nitrate reductase of white headed cabbage

W kapuście głowiastej białej oznaczono aktywność reduktazy azotanowej, poziom magnezu i poziom witaminy C. Następnie zbadano wpływ jonów magnezowych i witaminy C na zmiany aktywności enzymu. Uzyskane wyniki wykazały, że zarówno jony magnezowe jak i witamina C (w zakresie stosowanych stężeń) istotnie wzmagały aktywność reduktazy azotanowej kapusty.The aim of this study was to investigate the effect of magnesium ions and vitamin C on changes in the activity of nitrate reductase of white headed cabbage. During storage of cabbage the activity of nitrate reductase was investigated by the Jaworski method, the level of magnesium by complexometronic method and the level of vitamin C by the Pijanowski method. In addition, the effect of a supplement of magnesium and vitamin C on some changes in the activity of the enzyme was tested. For this puropse, to the incubation mixture, containing the material under study, magnesium ions in the form of magnesium chloride or vitamin C were added in respective quantities. It was found that the nitrate reductase activity as well as the level of magnesium and vitamin C are decreasing towards the inside layers of headed cabbage. Statistical evaluation of the results indicates a high by significant correlation between factors under study. A supplement of magnesium ions or vitamin C to the investigated cabbage significanty incerases the activity of the enzyme

Wplyw procesu fermentacji na zmiane poziomu azotanow i azotynow w wybranych warzywach

Badano zmiany poziomu azotanów i azotynów w czasie procesu fermentacji kapoty głowiastej białej, czerwonej oraz buraków ćwikłowych. Uzyskane wyniki wskazują na wysoce istotny wpływ tego procesu na redukcję zarówno azotanów jak i azotynów.The aim of this study was to follow the changes in the levels of nitrates and nitrites throughout the process of fermentation of sauerkraut from white and red cabbage and red beets. The nitrate and nitrite levels were determinated in raw and fermentation as well as in red beets and "beet acid" after a week of souring. Nitrate were determinated by the brudne method, while nitrates by the Griess colorimetric method. Mean reduction of nitrates in sauerkraut (in relation to raw cabbage) was ca. 55.5% and that of nitrites ca. 76.7%. In the red sour cabbage a decrease in the level of nitrates in relation to the product by ca. 84.1% and in that of nitrites by ca. 67.4% was found. The stabilization of both nitrate levels in both kinds of cabbages followed as after the second month of storage, as confirmed by statistical analysis of the results. In the red beets after the process of fermentation a decrease in the level of nitrates by ca. 91.6% was noted. An undefined portion of the studied compounds passed into the liquid. The "beet acid" contained 595.9 mg/dm1 of nitrates and 3.26mg/dm3 of nitrites