Nitrosamines
Mostrando 13-24 de 35 artigos, teses e dissertações.
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13. Degradation of N-Nitrosamines by Intestinal Bacteria
A major proportion of bacterial types, common in the gastrointestinal tract of many animals and man, were active in degrading diphenylnitrosamine and dimethylnitrosamine, the former being degraded more rapidly than the latter. At low nitrosamine concentrations (<0.05 μmol/ml), approximately 55% of added diphenylnitrosamine, 30% of N-nitrosopyrrolidine, and
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14. Formation of N-nitrosamines from seconday animes and nitrite by resting cells of Escherichia coli B.
In the presence of resting cells of Escherichia coli B, the formation of N-nitrosamines from nitrite and secondary amines, such as dimethylamine and piperidine, was proportional to the incubation time and to the cell concentration. Optimum pH was 8.0. Boiled cells were incapable of nitrosating secondary amines. Although these experiments were carried out by
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15. Prospective study of meat intake and dietary nitrates, nitrites, and nitrosamines and risk of adult glioma123
Background: The hypothesis that nitrosamine exposure may increase the risk of glioma has been circulating for several decades, but testing it has been difficult because of the ubiquitous nature of nitrosamine exposure. Diet has been the focus of many studies because it can substantially influence nitrosamine exposure, mostly from the endogenous formation of
American Society for Nutrition.
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16. Metabolism of tobacco-specific N-nitrosamines by cultured human tissues.
N'-Nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are present in cigarette smoke and snuff and are carcinogens in laboratory animals. In tobacco smokers, the buccal mucosa, trachea, esophagus, bronchi, and peripheral lung are exposed to smoke containing significant amounts of these N-nitrosamines. The results of the present
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17. Prophage Induction in Lysogenic Escherichia coli with N-Nitroso Compounds and Derivatives
Prophage induction in lysogenic Escherichia coli W1709 (ι) was determined for 29 N-nitroso compounds, 13 of their denitrosated derivatives, and 7 hydroxylamino and hydrazino analogues of nitrosamines. Minimal inducing concentrations of 0.1 to 2.0 μg/ml were demonstrated for eight nitrosamidines, and concentrations of 0.5 to 25.0 μg/ml were shown for six n
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18. Relationship between Schistosomiasis and Bladder Cancer
Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis,
American Society for Microbiology.
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19. alpha-Hydroxylation pathway in the in vitro metabolism of carcinogenic nitrosamines: N-nitrosodimethylamine and N-nitroso-N-methylaniline.
Evolution of 15N2-labeled molecular nitrogen was used to gauge the extent of alpha-hydroxylation during rat liver homogenate metabolism of doubly 15N-labeled N-nitrosodimethylamine (DMN) and N-nitrosomethylaniline (NMA). These measurements were correlated with the extent of total metabolism as measured by the disappearance of the nitrosamines and by the form
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20. Effect of Sodium Nitrite and Sodium Nitrate on Botulinal Toxin Production and Nitrosamine Formation in Wieners
Wieners were formulated and processed approximating commercial conditions as closely as possible. Twenty-four batches of product were made with the addition of six levels of sodium nitrite (0, 50, 100, 150, 200, and 300 μg/g), four levels of sodium nitrate (0, 50, 150, and 450 μg/g), and two levels of Clostridium botulinum (0 and 620 spores/g). After formu
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21. Microbial Formation of Nitrosamines In Vitro
Mortierella parvispora and an unidentified bacterium converted trimethylamine to dimethylamine, and the bacterium (but not the fungus) formed dimethylnitrosamine in the presence of nitrite. Dimethylnitrosamine also appeared in cell suspensions of Escherichia coli and Streptococcus epidermidis and in hyphal mats of Aspergillus oryzae incubated with dimethylam
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22. Occupational exposure and cancer of the pancreas: a review.
Many hypotheses have been proposed about the aetiology of cancer of the pancreas, especially concerning the effects of tobacco, coffee, alcohol, diet, and pancreatic pathology. Results of numerous epidemiological studies are, however, inconsistent. Chemical carcinogens have been implicated as possible risk factors. Animal studies have been carried out to det
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23. Malignant Transformation of BHK21 Clone 13 Cells In Vitro by Nitrosamines—A Conditional State
All the BHK21 Clone 13 cells transformed by dimethylnitrosamine or nitrosomethylurea, and a single “spontaneously” transformed clone obtained in our laboratory, exhibit a conditional state of the transformed phenotype. Upon growth at 38.5°, they have a transformed phenotype (clonal morphology and the ability to plate in soft agar); when grown at 32°, t
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24. Antimicrobial effect of acidified nitrite on gut pathogens: importance of dietary nitrate in host defense.
Dietary intake of nitrate generates salivary nitrite, which is acidified in the stomach, leading to a number of reactive intermediates of nitrogen, among which are the potentially carcinogenic N-nitrosamines. Acidified nitrite, however, also has antimicrobial activity which coincides with the formation of nitric oxide. The present study examines the antimicr