Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0546837 (esophageal cancer)
 8,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brief reviews are presented on the occurrence of N-nitroso (NNO) compounds, the chemistry and kinetics of NNO compound formation from nitrite and amines or amides, the in vivo formation of these compounds (as detected by tumor induction) on feeding nitrite with amines or amides to rodents, and the carcinogenicity for rats of some new nitrosamides. The possible human hazard caused by exposure to specific readily nitrosated compounds is reviewed. Whether NNO compounds might be causing human cancer of various organs (e.g., pancreatic, nasopharyngeal, and esophageal cancer) is discussed. Some of our results in [3H]thymidine incorporation in the rat esophageal epithelium are presented. Nitrosamines that cause esophageal cancer in rats were found to inhibit [3H]thymidine incorporation, both in vivo and in vitro, when esophagi were incubated with nitrosamines. With reference to the hypothesis that human gastric cancer is caused by nitrosamides (e.g., nitrosoureas), certain correlations were examined between gastric cancer and environmental exposure to nitrate, nitrite, and nitrosatable amides. In studies from our laboratory, dried, salted fish, which was treated with excess nitrite at pH 1 and then "denitrosated" at pH O, yielded 16 mg methylurae/kh fish, possibly derived from methylguanidine.
 ...
PMID:N-nitroso compounds: their chemical and in vivo formation and possible importance as environmental carcinogens. 32 17

A stepwise clustering algorithm, a method of multivariate statistical analysis, is suggested in this paper. The algorithm is designed for solving problems connected with stepwise regression. It is efficient not only in handling both continuous and discrete variables, but also in the nonlinear relationships between the variables. The above procedure was used in an attempt to find out the causal association of esophageal cancer with its precursors, i.e. nitrates and nitrites of nitrosamines, some of which are known to be carcinogenic. An analysis has been made of the correlation between esophageal cancer as well as severe epithelial hyperplasia of the esophagus and the concentrations of NO3- and NO2- in the drinking water. The samples used were collected from 495 wells in 49 production brigades of the Yaocun Commune in Linxian County, Honan Province. The result indicates that esophageal cancer is definitely connected with the levels of NO3- (summer) and NO2- (spring) in the drinking water. Severe epithelial hyperplasia is defintely connected with the contents of NO2- and NO3- in the drinking water collected in spring, autumn and winter. Our preliminary analysis shows that the stepwise clustering algorithm is a useful statistical method to be used for medical research.
 ...
PMID:Application of stepwise cluster analysis in medical research. 51 29

Humans are exposed to preformed N-nitroso compounds (NOC), but also to a wide range of precursors and nitrosating agents which can react in vivo to form potentially carcinogenic NOC and diazo compounds. Nitrite, nitrate and nitrosating agents can also be synthesized endogenously in enzymic reactions mediated by bacteria, activated macrophages and neutrophils. The latter two cell types generate, via the enzyme nitric oxide synthase, the nitric oxide radical that is involved in cytotoxicity, and is believed to be involved in formation of carcinogenic nitrosamines, DNA base deamination and oxidative damage. Thus endogenous NOC formation, DNA damage and gene mutations in humans could occur at various sites of the body such as the stomach and chronically infected or inflamed organs. Sensitive procedures to estimate the exposure of humans to NOC have been developed and applied in ecological and cross-sectional studies. These have shown that inhabitants of high-risk areas for stomach and esophageal cancer, patients with urinary tract infections (at risk for bladder cancer) and Thai subjects infected with liver fluke (at risk for cholangiocarcinoma) had significantly higher exposure to endogenous NOC. Clinical studies have examined the model of stomach carcinogenesis based on intragastric nitrosation, but the precise roles of bacterial overgrowth and of Helicobacter pylori infection in NOC synthesis and/or inducing oxidative stress in stomach mucosa remain to be clarified. Together these results support the role of NOC and other nitrite-derived mutagens in human cancer etiology, in particular when exposure starts early in life and persists over a long period.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Endogenously formed N-nitroso compounds and nitrosating agents in human cancer etiology. 133 85

Pickled vegetables are daily food consumed in the high-risk areas for esophageal cancer in China. We analyzed the nitrosamine content of Linxian pickles by GC/TEA and found that trace amounts of six nitrosamines (NDMA, NDEA, NMBA, NMAMBA, NDPA, NPYR) were present, with the highest concentrations being NDMA and NDEA (1.7 and 1.9 micrograms/kg wet weight respectively). The average level of nitrosamine precursors, such as nitrate (111.22 mg/L), nitrite (0.152 mg/L) and secondary amines (4.223 mg/L), in pickled vegetables were determined, and their pH values ranged from 3 to 5.
 ...
PMID:[Studies of pickled vegetables and cause of esophageal cancer in Linxian. II. Determination of nitrosamines and their precursors]. 183 33

Although no absolute certainty exists about the role of nutrition in the etiology of cancer, many facts in favor of the relationship became available during the last decades. Correlation studies, experimental work and to a lesser extent case-control studies made it possible to clarify the role of certain nutrients and foods in carcinogenesis. The most important cancer sites where nutrition could play a role are esophagus, stomach, colon, rectum, prostate and breast. Esophageal cancer is of a very complex etiology, in which alcohol intake plays an important role, at least in western countries. The cancer-promoting properties of alcohol intake are enhanced by smoking. Three factors from nutrition are probably related to stomach cancer, namely salt, nitrate/nitrite and vitamin C. Salt is caustic to the stomach mucosa, resulting in atrophic gastritis. Salt is also co-carcinogenic and stomach cancer-promoting in experimental animals. Nitrate is probably important at the stage of atrophic gastritis, where bacterial overgrowth, due to the high pH, converts nitrates in nitrites, making the loco synthesis possible of potent nitrosocarcinogens. Vitamin C inhibits the latter step. The epidemiological evidence for the role of those factors is provided. The most important among them is the strong and consistent association of stomach cancer mortality with stroke. Rectum, colon, prostate and breast cancer are related in some way to fat intake. They all seem positively related to saturated fat intake, whereas breast cancer is probably also promoted by polyunsaturated fat intake. However, polyunsaturated fat seems to be without effect on rectum cancer. Colon and prostate cancer are probably also influenced by polyunsaturated fat but to a lesser degree than breast cancer. An important argument for this are the positive ecological correlations between changes in rectum, colon and breast cancer mortality from 1968 on, and changes occurring in coronary heart diseases, stroke and diabetes mortality. Those six types of mortality are decreasing, or only slightly increasing in the USA, Belgium, France, the Netherlands, etc. They are strongly increasing in East European countries. The intake of saturated fat has generally decreased in the first group of countries, and has markedly increased in the second group.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Nutrition and cancer. 353 16

A total of 238 samples of 24-h urine were collected from inhabitants of high-risk (Lin-xian) and low-risk (Fan-xian) areas for esophageal cancer in northern China, according to three protocols: (a) from undosed subjects; (b) from subjects who had ingested 100 mg L-proline three times a day 1 h after each meal; and (c) from subjects in Lin-xian who had ingested 100 mg ascorbic acid together with 100 mg L-proline three times a day 1 h after each meal. As an index of individual exposure to N-nitroso compounds or their precursors, ingested in food and/or formed endogenously, the levels of four urinary N-nitrosamino acids and nitrate were determined. The amounts of N-nitrosoproline, N-nitrosothiazolidine 4-carboxylic acid, N-nitrososarcosine, and nitrate excreted in the 24-h urine of undosed subjects in Lin-xian were significantly higher than those in Fan-xian, indicating a higher exposure of the inhabitants in the high-risk area to N-nitroso compounds and their precursors. Ingestion of L-proline resulted in a marked increase in urinary N-nitrosoproline levels in inhabitants from both areas, suggesting that endogenous nitrosation may occur to a larger extent when appropriate amine precursors are ingested in foods. Intake of moderate doses of ascorbic acid by high-risk subjects effectively reduced the urinary levels of N-nitrosamino acids to those found in undosed subjects in the low-risk area. If N-nitroso compounds formed in vivo are among the causative factors for esophageal cancer in this area of northern China, ascorbic acid appears to be effective in lowering the body burden of these carcinogenic compounds, thus offering a rational basis for long-term intervention studies in this area.
 ...
PMID:Urinary excretion of N-nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for esophageal cancer in Northern China: endogenous formation of nitrosoproline and its inhibition by vitamin C. 394 5

A survey is given on the occurrence of nitrate and nitrite in human saliva and the influence of the dietary nitrate intake. Nitrate, after its absorption in the upper gastrointestinal tract, reaches the salivary glands via the blood circulation where it is secreted into the oral cavity and partially reduced to nitrite by the oral microflora. There is a linear relationship between the amounts of nitrate ingested and amounts of nitrate and nitrite found in saliva. The ability of the oral microflora to reduce nitrate to nitrite depends on he individual ages. Mean salivary nitrite was found to increase from well below 1 ppm in infants of up to 6 months to about 7 ppm in adults. a remarkably different situation has been found in areas of high esophageal cancer incidence in Iran: although dietary intake of nitrate and nitrite is very low, nitrite levels in saliva, especially in children of this area tend to be much higher than those in children of western European countries.
 ...
PMID:Nitrate and nitrite in saliva. 744 55

Evidence from animal studies indicates that various N-nitroso compounds are carcinogenic. We investigated whether consumption of foods and beverages containing nitrosodimethylamine, nitrites, and nitrates affected the risk of laryngeal, esophageal, and oral cancer. In a population-based case-control study in western Washington state, dietary consumption of these substances was measured in 645 cases (169 laryngeal, 125 esophageal, and 351 oral) and 458 controls. After adjustment for tobacco, alcohol, and other known risk factors, there was a 52% reduction in the risk of upper aerodigestive tract cancer for individuals who consumed higher amounts of nitrate (upper tertile) compared with the lowest tertile (P < 0.001 for trend). Nitrate intake was associated with a reduction in cancer risk at all three sites. The reduction in the risk of esophageal cancer with increasing nitrate consumption was more evident in frequent tea drinkers than in other subjects. There was no significant association between nitrite consumption and the risk of laryngeal or oral cancer. However, for individuals with a history of canker sores (an indicator of possible endogenous nitrosation), the risk of esophageal cancer was seven times greater in those with high versus low nitrite intake. Consumption of foods high in nitrosodimethylamine was associated with a 79% increased risk of upper aerodigestive tract cancer (P = 0.037 for trend). Cases consumed smoked fish more frequently than did controls [odds ratio (OR) = 3.03]. Daily intake of beer and of nitrite-containing meats were associated with an increased esophageal cancer risk (OR = 2.48 and 1.82, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Consumption of nitrate, nitrite, and nitrosodimethylamine and the risk of upper aerodigestive tract cancer. 789 21

A total of 31 corn samples collected from households in the counties of Cixian and Linxian of the People's Republic of China, where high incidences of esophageal cancer have been reported, were analyzed for fumonisin B1 (FB1), aflatoxin, and total trichothecene mycotoxins. High levels of FB1 (18 to 155 ppm; mean, 74 ppm) were found in 16 of the samples that showed heavy mold contamination. FB1, at lower levels (20 to 60 ppm; mean, 35.3 ppm), was also found in 15 samples, collected from the same households, that did not show any visible mold contamination. The levels of aflatoxin in the samples were low (1 to 38.4 ppb; mean, 8.61 ppb). High levels of total type-A trichothecenes were also found in the moldy corn samples (139 to 2,030 ppb; mean, 627 ppb). Immunochromatography of selected samples revealed that these samples contained T-2 toxin, HT-2 toxin, iso-neosolaniol, monoacetoxyscirpenol, and several other type-A trichothecenes. The concentration of total type-B trichothecenes in 15 moldy corn samples was in the range of 470 to 5,826 ppb (mean, 2,359 ppb). High levels (3.7 to 5.0 mg/g) of FB1 were produced in corn in the laboratory by five Fusarium moniliforme strains isolated from the moldy corn. These fungi were also capable of forming various nitrosamines (5 to 16 micrograms per flask) in the presence of nitrate and precursor amines.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Simultaneous occurrence of fumonisin B1 and other mycotoxins in moldy corn collected from the People's Republic of China in regions with high incidences of esophageal cancer. 816 Nov 78

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.
 ...
PMID:Geographic association between urinary excretion of N-nitroso compounds and oesophageal cancer mortality in China. 832 1


1 2 Next >>