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PubMed1984

Pancreatic carcinogenic nitrosamines in Syrian hamsters.

Pancreatic neoplasms similar to those seen in humans have been induced by a group of related nitrosamines only in Syrian golden hamsters. Studies indicate a relationship between the structure of the carcinogens and their affinity for the pancreas: the presence of one keto or hydroxy group in the beta-position on one of the aliphatic chains of alkyl nitrosamines is a prerequisite for their pancreatic carcinogenicity; addition of a second beta-keto group significantly increases their activity on and specificity for the pancreas; replacement of one 2-oxo chain with a methyl group diminishes their specificity for the pancreas as does prolongation of the aliphatic chain. Carboxylation at the 3-position is associated with a complete loss of pancreatotropism. N-Nitrosomethyl(2-oxopropyl)amine appears to be a proximate carcinogenic metabolite of these compounds. The lack of tumour induction in the pancreas of rats correlates with the inability of this species to metabolize carcinogens to this metabolite, whereas all the pancreatic cells of the hamster (ductal/ductular, acinar and islet cells) have this ability. The results of in-vivo and in-vitro studies strongly suggest that the hamster pancreatic ductal and ductular cells are the most active unit of the organ in metabolizing the carcinogen and are also the progenitor cells of the induced pancreatic lesions.

Animals↗
PubMed1984

Pharmacokinetics of tobacco-specific N-nitrosamines.

Methods were developed to determine the biological half-life of N'-nitrosonornicotine (NNN) and 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) in Syrian golden hamsters and Fischer rats. The formation and elimination of 4-(N-nitrosomethylamino)-1-(-3-pyridyl)-1-butanol (NNA1), the major metabolite of NNK, was determined in the context of this study. The method consisted of extraction of the nitrosamine with ethyl acetate, elution through a Clin-Elut column, and concentration of the sample, followed by gas chromatography-thermal energy analysis. Biological half-lives of NNN, NNK and NNA1 in hamsters were found to be 0.77, 0.25 and 1.78 h, respectively; in rats they were 5.78, 1.78 and 3.56 h. These findings clearly indicate species differences in the pharmacokinetics associated with the distribution and elimination of the tobacco-specific N-nitrosamines.

Animals↗
PubMed1984

A new N-nitroso compound, N-2-methylpropyl-N-1-methylacetonyl-nitrosamine, in moldy millet and wheat flour.

A new N-nitroso compound, N-2-methylpropyl-N-1-methylacetonyl-nitrosamine (MAMPNA), was found in millet and wheat flour inoculated with Fusarium moniliforme Sheldon, a common species of fungi occurring in foods in Linxian County, after 8-day incubation and an addition of a small amount of NaNO2. The compound has been identified by GC-MS and confirmed by synthesized MAMPNA. The present paper reports the isolation and detection of MAMPNA in moldy foods, and discusses the role of the fungus in processes of nitrosamine formation and possible biosynthetic approach of the new compound.

Chromatography, Thin Layer↗
PubMedDate not supplied

High temperature purge and trap procedure for determining seven volatile N-nitrosamines in animal feed, using gas chromatography/thermal energy analyzer.

A rapid and sensitive procedure is described for determining 4 N-nitrosodialkylamines (dimethyl, diethyl, dipropyl, and dibutyl) and the N-nitroso analogs of piperidine, pyrrolidine, and morpholine in animal feed. The volatile N-nitrosamines were isolated by using a modified high temperature purge and trap apparatus designed for multiple sample cleanup. The feed sample was mixed with mineral oil and a nitrosation inhibitor, and the N-nitrosamines were purged onto a ThermoSorb/N cartridge, eluted with acetone-dichloromethane (1 + 1), and determined by gas chromatography, using a thermal energy analyzer. The effects of purge rate, purge time, and temperature on recovery are discussed. Feed samples spiked with 10, 50, and 200 ppb of the 7 N-nitroso compounds yielded recoveries ranging from 70 to 97%, with precision ranging from 1.3 to 5.4% and minimum detectable levels in the low parts-per-billion range.

Animal Feed↗
PubMed1982

A sensitive assay for mutagenic activity of N-nitrosamines and its use for detection of modulators of the mutagenicity.

By carrying out the pre-incubation of bacteria with N-nitrosamines under acidic conditions, the mutagenicity of N-nitrosodimethylamine on Salmonella TA100 and E. coli WP2 try, hcr was detected with increased sensitivity, compared to usual assays in neutral buffers. Using this modified assay system, compounds have been screened for their modulating effects on N-nitrosamine-mediated mutagenesis and the following were found to be inhibitors: cysteine, cysteamine, bisulfite, n-propylamine, n-butylamine, n-hexylamine, n-octylamine, n-nonylamine, serotonine, tryptamine, epinephrine, norepinephrine and oleic acid. The mechanisms of inhibition are discussed.

Amines↗
PubMed1980

Synthesis and mutagenicity of 4-(N-butylnitrosamino)-4-hydroxybutyric acid lactone, a possible activated metabolite of the proximate bladder carcinogen N-butyl-N-(3-carboxypropyl)nitrosamine.

4-(N-Butylnitrosamino)-4-hydroxybutyric acid lactone (BBAL) was synthesized as a possible intermediate produced by metabolic activation of a selective bladder carcinogen, N-butyl-N-(3-carboxypropyl)nitrosamine. BBAL was stable in neutral sodium phosphate buffer (ionic strength, 0.2), having a half-life of more than 30 hr at 25 degrees. The mutagenic effects of BBAL were tested with the use of Salmonella typhimurium TA1535 and Escherichia coli B/rWP2-try-, WP2-try-hcr-, and Sd4. The gene-damaging effects were assayed by repair tests with Bacillus subtilis H17 (rec+) and M45 (rec-). BBAL showed potent effects in the mutation and repair tests on all the strains tested without activation. A possibility is suggested for the metabolic activation of N-butyl-N-(3-carboxypropyl)nitrosamine to BBAL by alpha-hydroxylation at the site of the 3-carboxypropyl chain followed by lactonization in target tissues prior to interaction with macromolecules to lead to carcinogenesis.

Bacillus subtilis↗
PubMed1982

Volatile N-nitrosamines in direct flame dried processed foods.

The presence of N-nitrosodimethylamine (NDMA) in malt and malt beverages has been linked to the direct flame drying of malt. Similar drying procedures are used in the preparation of a variety of foods, such as non-fat dry milk, soy proteins and dried cheeses. A survey of some of these processed foods for volatile N-nitrosamines has shown that low levels of NDMA are present, along with N-nitrosomorpholine in one sample of soy protein isolate. This paper describes the procedures used for the analysis of a variety of processed dried foods for volatile nitrosamines and reports the results obtained.

Animals↗
PubMed1978

[Influence of microorganisms on the formation of nitrosamines].

The N-nitroso compounds synthesis from amine and nitrite contained in food is influenced by many factors: -the pH; -the temperature; -the amine basicity; -the presence of organic groups which catalyse or inhibit the reaction. The chemical nitrosation of the amino group takes place at pH between 2 and 4,5. At the near neutrality pH of most of food, this synthetis, cannot be realised. Under these conditions the nitrosamine occurence can be explained by the effect of microorganisms. We have studied the influence of moulds used in cheese making on the nitrosation reaction in a middle where nitrate and amino groups are found together. The middles are realised on caseine or curdled milk, and contained 150 mg/l of nitrate and 100 mg/l of piperidine. The nitrosopiperidine has been identified in all the middles studied. The results are discussed concerning the risk of nitrosamine formation of this type of food during the technological process.

Amines↗
PubMed1982

Malt beverages and brewing materials: screening and confirmatory methods for nitrosamines in beer.

Screening methods for nitrosamines in beer were studied by 15 collaborators. Collaborators studied 4 extraction techniques and 2 calculation procedures. All methods showed acceptable recoveries and no significant differences between methods. Based on accuracy, simplicity and speed, the Celite extraction with internal standard calculation is recommended. Fifteen collaborators also studied a distillation confirmatory method compared with a direct extraction with dichloromethane. Because the former gives an extract more suitable for mass spectrometric confirmation of nitrosamines, it is the recommended reference method. The screening and confirmatory methods have been adopted official first action.

Beer↗
PubMed1982

Malignant transformation of baby hamster lung fibroblasts induced in vitro by a new nitrosamine compound.

A new nitrosamine compound, N-1-methylacetonyl-N-3-methylbutyl-nitrosamine (MAMB-NA), isolated from corn bread inoculated with moulds commonly occurring in Linxian County, a high incidence area for esophageal cancer in North China was tested for its potential carcinogenicity in vitro. Baby hamster lung fibroblasts (BHL) were treated with MAMBNA in tissue culture medium containing liver microsome preparation of Aroclor 1254 treated rat. Cell transformation was assessed by morphological changes, loss of density-dependent inhibition and unlimited growth in vitro, chromosome changes, colony formation on soft agar, growth at low serum concentration, Con A agglutinability and tumor formation after heterotransplantation into immunosuppressed newborn rats. Like the known carcinogens N-methyl-N'-nitro-N-nitroso-guanidine and diethylnitrosamine, MAMBNA was able to cause malignant transformation of cells cultured in vitro.

Animals↗
PubMed1982

Endogenous synthesis of volatile nitrosamines: model calculations and risk assessment.

A kinetic model for estimating the gastric synthesis of N-nitroso compounds and a method for estimating the risk from exposure to volatile nitrosamines are described. A tentative calculation of the possible risks for human gastric cancer, based on extrapolating from literature data on the induction of tumours in rats, suggests that the endogenous formation of non-volatile N-nitroso compounds is more important than that of volatile nitrosamines.

Food Analysis↗
PubMed1982

Nitrosamine formation from ternary nitrogen compounds.

When amides of pyrrolidine are heated with sodium nitrite, small amounts of NPYR are formed. Both the rate of reaction and the nitrosamine yield are increased when ethylene glycol and glycerine are used as solvents. Kinetic evidence suggests that these polyols react with the amide to form esters and the corresponding amine. The esters then react with sodium nitrite to give nitrite esters which rapidly nitrosate the amine. The heating of LDEA with sodium nitrite gives relatively high yields of NDELA in relatively short times and this nitrosation can be explained by this mechanistic hypothesis. 2-N,N-dimethylaminomethylpyrrole reacts very rapidly with nitrous acid at 25 degrees to give NDMA as the sole nitrosamine. This suggests a new mechanism of tertiary amine nitrosation.

Amides↗
PubMed1982

Association of cigarette smoking and nitrosamines with urinary bladder cancer: a review.

Past studies have shown that the association of cigarette smoking with urinary bladder cancer is positive. On this basis, blacks and Polynesians in the Pacific Basin should have higher rates of bladder cancer than observed, especially in view of their high risk for lung cancer and their frequency of smoking cigarettes. Studies were proposed as a result of the above observations. Several investigators have attempted to measure components of nitrosamines in urine specimens of patients with bladder cancer, cigarette smokers, and controls. The limitations of their studies are discussed, and new studies are proposed if the methods of nitrosamine analysis can be improved in the future.

Animals↗
PubMed1981

Carcinogenic tobacco-specific N-nitrosamines in snuff and in the saliva of snuff dippers.

Human data indicate an increased risk for cancer of the oral cavity for snuff dippers. Popular snuff products from the United States, Germany, Sweden, and Denmark were analyzed for tobacco-specific N-nitrosamines (TSNA). These compounds are formed during tobacco processing from nicotine, nornicotine, and anatabine and represent the only known carcinogens in snuff. N'-Nitrosonornicotine, a moderately active carcinogen, ranged in dry snuff from 3.5 to 77 ppm; 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, a relatively strong carcinogen, ranged from 0.6 to 7.0 ppm; and N'-nitrosoanatabine, thus far not bioassayed, ranged from 0.8 to 44 ppm. The concentrations of TSNA in a given snuff product can vary widely, and aging in the open air can lead to an increase in TSNA. Analysis of the saliva of snuff dippers revealed that these nitrosamines are extracted from the tobacco plug during snuff dipping and that their concentrations in saliva can vary widely between users. Efforts should be made to reduce the TSNA in snuff by modifications of the production process and by wrapping individual snuff portions in airtight packets.

Adult↗
PubMed1980

Synthesis of monosaccharide nitrosamines.

This paper describes the chemical synthesis of a chain-branched, monosaccharide nitrosamine: 3-[N-nitroso-N-ethyl]-aminomethyl-D-allose. Nitrosamines with alpha-carbon-carbon-bonded carbohydrate residues (hydrophilic carrier) could be interesting for experimental cancer research; specifically, in biological experiments (testing for carcinogenic, mutagenic or teratogenic effects), biochemical experiments (enzymatic activation, metabolites) and physiological experiments (resorption studies).

Hexoses↗
PubMed1980

Comparison of analyses of wastewaters for N-nitrosamines using various detectors.

Three GC detectors, the AFID, the TEA and the Hall (pyrolytic mode), were evaluated for the monitoring of wastewaters for NDMA, NDPA and NDPhA. All three detectors were adequate for NDMA and NDPA determinations. Due to its thermal lability, NDPhA has to be determined indirectly as its degradation product, DPhA, using the AFID. A column clean-up method for removing DPhA from samples prior to GC analysis is described. Since both the TEA and the Hall (pyrolytic mode) detectors utilize pyrolysis after gas chromatography, they are not satisfactory for NDPhA monitoring. Wastewater analysis using all three detectors gave comparable data; however, the lack of nitrosamine selectivity in the AFID requires both that the sample undergo an initial clean-up and a longer GC bake-off time. It is also noted that the Hall detector used in the pyrolytic mode may offer some advantages for routine nitrosamine monitoring; and is less restricted in its utility than the TEA.

Aluminum Oxide↗
PubMed1980

Occurrence of volatile nitrosamines in food: a survey of the West German market.

More than 3000 food samples from the West German market have been analysed for volatile nitrosamines. N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP) in concentrations above 0.5 micrograms/kg were found in only 3 and 2% of the samples, respectively. N-Nitrosodimethylamine (NDMA) was detectable in 30% of the samples and 6% of them were found to contain more than 5 micrograms/kg. Consumption data given in the "Nutritional Report, 1976" allow calculation of the average daily intake of volatile nitrosamines from food. Intakes for West German males are 1.1 micrograms/day for NDMA and 0.1 micrograms/day for NPYR. With regard to NDMA, the relative contributions are 64% for beer, 10% for meat and meat products and 25% for all other foods (150 types). NDMA in beer originates in the malt, where it is formed during kilning (drying). Technological improvements to eliminate NDMA contamination of beer are reported.

Beer↗
PubMed1980

The penetration of rat skin by some nitrosamines of environmental importance.

N-Nitrosomorpholine (NMOR) and N-nitrosodiethanolamine (NDELA) were applied to the clipped dorsal skin (about 3.5 X 3.5 cm) of adult male Fischer 344 rats. NDELA was applied undiluted, dissolved in water and dissolved in cutting oil; NMOR was applied dissolved in water and in ethyl acetate. To compare the extent of absorption through the skin with that from the stomach, aqueous solutions of the nitrosamines were used for gavage. Blood and urine samples were analysed for nitrosamines, using GC-TEA or HPLC-TEA. Maximum skin penetration observed with NMOR was 56%, following application of 5 mg, whereas a similar proportion of the dose was regularly present after gavage of 5 mg. Less than 1% was recovered from the urine. Skin painting of NDELA in water (20 mg in 100 microliter) and in cutting oil (25 mg in 25 microliter) yielded small concentrations of NDELA in the blood; less than 25 mg/l in all cases. However, when 50 mg NDELA was painted on the skin undiluted, from 130 to 220 mg/l of blood were recovered after one hour. fifty mg NDELA in water yielded similar blood concentrations when administered by gavage. From 20 to 30% of the NDELA applied undiluted and by gavage were recovered in the urine. It is concluded that, although there are differences between animals, exposure to NMOR or NDELA represents a risk due to absorption through the skin.

Animals↗