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S S Hecht

Publications and source records attributed to S S Hecht.

At least 145 records · Page 8Linked to original sources
PubMed1992

Formation of 7-(4-oxobutyl)guanine in hepatic DNA of rats treated with N-nitrosopyrrolidine.

We have reported previously the formation of two structurally distinct exocyclic guanine adducts (adducts 1 and 6) in liver DNA of F344 rats treated with N-nitrosopyrrolidine (NPYR). In this study, we detected and characterized a previously unidentified guanine adduct in liver DNA of NPYR-treated rats. The structure of this adduct was established as 7-(4-oxobutyl)guanine (adduct 2) by comparison with the synthetic standard and confirmed by NaBH4 reduction to 7-(4-hydroxybutyl)guanine. The level of adduct 2 in liver DNA of F344 rats treated with 450 mg/kg of NPYR by i.p. administration was 643 +/- 9 mumol/mol guanine, approximately one-third of the level of adduct 1. This study is the first to demonstrate the in vivo formation of a formylalkyl-substituted guanine adduct by a nitrosamine.

Animals↗
PubMed1992

Comparative tumorigenicity of nitrochrysene isomers in newborn mice.

6-Nitrochrysene (6-NC) is a potent lung and liver carcinogen in the newborn mouse assay. In this report, we extended our studies of the structure--tumorigenicity relationships of the mononitrochrysene isomers. We synthesized 1-NC, 2-NC and 3-NC by oxidation of the corresponding aminochrysenes with mCPBA; efforts to synthesize 4-NC and 5-NC from 4- and 5-aminochrysene were not successful. The tumorigenic activities of 1-NC, 2-NC, 3-NC and 6-NC were compared. Groups of mice were treated with the appropriate compounds in dimethylsulfoxide (DMSO) by i.p. injection on the 1st, 8th and 15th day of life. At a total dose of 100 nmol/mouse, 6-NC induced significant incidences and multiplicities of lung tumors in mice in both sexes; only males were susceptible to liver tumor induction. At 100 nmol/mouse, induction of lung and liver tumors by 1-NC, 2-NC and 3-NC was not significantly different from that observed in mice treated with DMSO. The results indicate that nitro substitution at the 6-position of chrysene is critical for strong tumorigenicity in the newborn mouse assay.

Animals↗
PubMed1991

Quantitation of microsomal alpha-hydroxylation of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is activated to DNA alkylating species via two different alpha-hydroxylation pathways. Methylene hydroxylation leads to DNA methylation, whereas methyl hydroxylation yields DNA pyridyloxobutylation. We have developed a high-pressure liquid chromatography assay utilizing radiochemical detection that permits the determination of the extent of metabolism through each pathway in microsomal preparations. Levels of 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) were used to measure the extent of methyl hydroxylation, whereas levels of the aldehyde, 4-oxo-1-(3-pyridyl)-1-butanone (OPB), were used to quantify the extent of methylene hydroxylation. Incubations of [5-3H]NNK with microsomes and cofactors were conducted in the presence of 5 mM sodium bisulfite to trap the reactive OPB. The inclusion of bisulfite did not affect the rate of NNK metabolism. Trapping the aldehyde also inhibited its further oxidation to the corresponding acid or reduction to HPB. Furthermore, the conversion of HPB to OPB made only a minor contribution to the OPB levels under our incubation conditions. Analysis of incubation mixtures containing [5-3H]NNK, cofactors, and either A/J mouse liver or lung microsomes demonstrated that OPB was a significant metabolite of NNK. The OPB:HPB ratio was greater in liver (1.5) than in lung (0.2-1) microsomal preparations. Apparent Km values for OPB and HPB formation in lung microsomes were 23.7 and 3.6 microM, respectively, whereas the corresponding values for liver microsomes were 19.1 and 73.8 microM, respectively. These data are consistent with the involvement of more than one cytochrome P-450 isozyme in the activation of NNK to DNA reactive species.

Animals↗
PubMed1991

O6-methylguanine is a critical determinant of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone tumorigenesis in A/J mouse lung.

The relative importance of the two alpha-hydroxylation pathways in the tumorigenicity of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), was examined in the A/J mouse lung. Methyl hydroxylation, which results in DNA pyridyloxobutylation, was investigated with 4-(acetoxymethylnitrosamino)-1-(3-pyridyl)-1-butanone (NNKOAc) and N'-nitrosonornicotine. Methylene hydroxylation, which leads to DNA methylation, was studied by using acetoxymethyl-methylnitrosamine (AMMN). The tumorigenic activities of these compounds were compared to that of 10 mumol NNK at doses that yielded similar or greater adduct levels 24 h after exposure. The methylating agent AMMN was more tumorigenic than the pyridyloxobutylating agents, NNKOAc and N'-nitrosonornicotine. NNKOAc enhanced the tumorigenic activity of AMMN when the two compounds were given in combination. These results suggested that DNA methylation was more important than DNA pyridyloxobutylation in A/J mouse lung tumor induction by NNK and that pyridyloxobutylation enhanced the activity of the methylation pathway. However, the tumorigenicity of 10 mumol NNK could not be reproduced by AMMN +/- NNKOAc at doses that yielded similar levels of DNA adducts 24 h after exposure. Therefore, a second study was conducted in which the persistence of O6-methylguanine in lung DNA following various doses of NNK or AMMN +/- NNKOAc was compared to the tumorigenicity of these treatments. A strong correlation was observed between lung tumor yield and levels of O6-methylguanine at 96 h for NNK and AMMN +/- NNKOAc (r = 0.98). The ability of NNKOAc to increase the tumorigenic activity of AMMN was attributed to its ability to enhance the persistence of O6-methylguanine in lung DNA. These results demonstrate that the formation and persistence of O6-methylguanine are critical events in the initiation of A/J mouse lung tumors by NNK. They also suggest that DNA pyridyloxobutylation by NNK can increase the persistence of this promutagenic base in lung DNA.

Animals↗
PubMed1991

Tumorigenicity of the tobacco-specific carcinogen 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone in infant mice.

The tobacco-specific nitrosamine, 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is a potent carcinogen in adult rodents and variably effective transplacentally, depending on species. In pursuit of the thesis that human infants may be especially vulnerable targets for tumor initiation by tobacco smoke constituents, we tested the efficacy of NNK as a tumor initiator in infant mice. Cr:NIH(S) (NIH Swiss outbred) mice were given 50 mg/kg NNK i.p. on postnatal days 1, 4, 7, 10 and 14, with saline to controls. At an average age of 13-15 months, 57% of the NNK-exposed male offspring had hepatocellular tumors, with a multiplicity of 1.15 +/- 1.4, including 4 with carcinoma. Liver tumors including 2 carcinomas were found in 8 (14%) of the NNK-exposed female offspring. There were no hepatocellular neoplasms in any control. A significant increase in primary lung tumors also occurred in the NNK-treated males, with an incidence of 30/55 (57%) and a multiplicity of 0.7 +/- 0.2, vs. 7/33 (21%), multiplicity 0.3 +/- 0.6, in controls (P less than 0.025). An apparent increase in the incidence of lung tumors in NNK-treated females, 21/57 (37%) vs. 7/32 (22%) in controls, approached significance (P less than 0.1). Thus NNK was a moderately potent neonatal carcinogen for liver and lung in infant Swiss mice and more efficacious in this regard than when received transplacentally by mice of the same strain.

Animals↗
PubMed1991

Comparative tumorigenicity in newborn mice of chrysene- and 5-alkylchrysene-1,2-diol-3,4-epoxides.

We determined the tumorigenicity in newborn mice of racemic anti-1,2-diol-3,4-epoxides of chrysene, 5-methylchrysene, 5-ethylchrysene and 5-propylchrysene. Among the four diol epoxides, only anti-5-methylchrysene-1,2-diol-3,4-epoxide was highly tumorigenic. It was 15-30 times more potent in induction of pulmonary tumors than the other compounds. The results demonstrate that molecular shape is critical in determining the tumorigenic activity of alkylchrysene diol epoxides. A methyl group in the same bay region as the epoxide ring leads to exceptional activity. This may be a consequence of DNA adduct conformation.

Adenoma↗
PubMed1991

Structure-activity relationships for inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone lung tumorigenesis by arylalkyl isothiocyanates in A/J mice.

Phenethyl isothiocyanate (PEITC), 3-phenylpropyl isothiocyanate (PPITC), 4-phenylbutyl isothiocyanate (PBITC), and the newly synthesized 5-phenylpentyl isothiocyanate (PPeITC), 6-phenylhexyl isothiocyanate (PHITC), and 4-(3-pyridyl)butyl isothiocyanate (PyBITC) were tested for their abilities to inhibit tumorigenicity and DNA methylation induced by the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in the lungs of A/J mice. Mice were administered isothiocyanates by gavage for 4 consecutive days at doses of 5, 1, or 0.2 mumol/day prior to administration of 10 mumol of NNK by i.p. injection. Mice were sacrificed 16 weeks after NNK administration and pulmonary adenomas were quantitated, PEITC effectively inhibited NNK-induced lung tumors at a dose of 5 mumol/day but was not inhibitory at doses of 1 or 0.2 mumol/day. PPITC, PBITC, PPeITC, and PHITC were all considerably more potent inhibitors of NNK lung tumorigenesis than PEITC. While virtually no differences in inhibitory activity could be ascertained for PPITC, PBITC, and PPeITC, PHITC appeared to be the most potent tumor inhibitor of all of the compounds. At a dose of 0.2 mumol/day, PHITC pretreatment reduced tumor multiplicity by 85%. PyBITC, an analogue of both NNK and PBITC, was ineffective as an inhibitor. Using the same protocol, the compounds were found to have qualitatively similar inhibitory effects on NNK-induced DNA methylation when administered at 1 mumol/day. These results extend our previous findings that increased alkyl chain length enhances the inhibitory activity of an arylalkyl isothiocyanate toward NNK lung tumorigenesis and demonstrate the exceptional chemopreventive potentials of two new isothiocyanates, PPeITC and PHITC.

Animals↗
PubMed1991

In vivo and in vitro persistence of pyridyloxobutyl DNA adducts from 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

The persistence of pyridyloxobutyl DNA adducts in lung and liver of F-344 rats treated with the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was investigated. The levels of these adducts were determined at various time points up to 4 weeks post s.c. injection of [5-3H]NNK (0.8 mg/kg body wt). Maximal levels of the adducts were observed between 4 and 24 h in both tissues. The disappearance of the adducts from lung and liver DNA was multiphasic with initial half-lives of 50 and 38 h respectively. In both cases, detectable levels of the pyridyloxobutyl adducts were observed at 4 weeks post injection. The in vitro rate of adduct disappearance was studied using calf thymus DNA reacted with 4-(acetoxymethylnitrosamino)-1-(3-[5-3H]pyridyl)-1-butanone in the presence of esterase. Adduct levels were measured for up to 2 weeks after the initiation of the experiment. The decomposition of these adducts was triphasic with half-lives of 6, 120 and 430 h. The multiphasic disappearance of the pyridyloxobutyl adducts suggests that there is more than a single adduct generated upon pyridyloxobutylation of DNA and that at least one of these adducts has a significant lifetime in DNA.

Animals↗
PubMed1991

Effect of phenethyl isothiocyanate on the metabolism of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by cultured rat lung tissue.

The effect of phenethyl isothiocyanate (PEITC), a dietary inhibitor of carcinogenesis, on the metabolism of the tobacco specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by cultured rat peripheral lung tissues was investigated. Initially, the metabolism of NNK by the tissues was studied by incubating the lung explants in medium containing 1 and 10 microM [5-3H]NNK for 3, 6, 12, and 24 h. NNK metabolites were analyzed and quantified by HPLC and expressed as nmol/mg DNA. NNK was metabolized by three pathways; alpha-carbon hydroxylation, pyridine N-oxidation and carbonyl reduction. The principal metabolic pathway involved the conversion of NNK to the pyridine N-oxidized metabolites: 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide) and 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanol (NNAL-N-oxide). When combined, NNK-N-oxide and NNAL-N-oxide constituted approximately 70% of the total metabolites in the medium at 24 h. To determine the effects of PEITC on the metabolism of NNK, lung explants were either treated with both 10 microM [5-3H]NNK and PEITC (10, 50, and 100 microM) for 24 h, or they were pre-treated with these same concentrations of PEITC for 16 h and then co-treated with both PEITC and 10 microM [5-3H]NNK for 24 h. In both treatment series, PEITC inhibited the alpha-carbon hydroxylation and pyridine N-oxidation of NNK and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), which is produced from NNK by carbonyl reduction. In general, the inhibition of NNK metabolism was greater when the explants were pre-treated with PEITC. These results suggest that PEITC is an effective inhibitor of the conversion of NNK to metabolites that elicit DNA damage. Our results are in agreement with previously published data in which PEITC was shown to inhibit NNK metabolism and tumorigenesis in the rat lung.

Animals↗
PubMed1991

Comparative DNA binding of polynuclear aromatic hydrocarbons and their dihydrodiol and bay region diolepoxide metabolites in newborn mouse lung and liver.

Bay region diolepoxides of polynuclear aromatic hydrocarbons (PAHs) generally are more tumorigenic than their parent PAHs in newborn mice. This contrasts to the results obtained in mouse skin, in which the same diolepoxides are frequently less tumorigenic than their parents. In order to evaluate mechanism(s) responsible for this behavior we have investigated the binding of metabolites of [3H]benzo[a]pyrene (B[a]), [3H]5- and [3H6]6-methyl-chrysene (5-MeC and 6-MeC) and their corresponding dihydrodiols and bay region diolepoxides to pulmonary and hepatic DNA in male and female newborn mice and compared the results with their tumorigenic activities. Groups of 1 day old mice were treated with 0.4 or 4 nmol of the appropriate compounds in DMSO by i.p. injection. HPLC analysis of DNA hydrolysates obtained 24 h after treatment indicated that levels of diolepoxide-DNA adducts following treatment with (+-)-[3H]7,8-dihydroxy-7,8-dihydroB[a]P and (+-)-[3H]anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroB[a] P are 5- and 10-fold higher than those formed from [3H]B[a]P. The major products (70-80%) released upon enzymatic hydrolysis of DNA following treatment with [3H]B[a]P, [3H]5-MeC and [3H]6-MeC were unidentified polar compounds. Levels of these unknown products were lower and formation of diolepoxide--DNA adducts higher when test compounds were changed from parent PAHs to the corresponding dihydrodiols and diolepoxides. Comparison of these results with those of tumorigenesis studies indicates a correlation between formation of B[a]P-diolepoxide--DNA adducts and induction of tumors in newborn mouse lung, but not in liver. These observations are consistent with the high sensitivity of the newborn mouse lung towards the tumorigenic effects of bay region diolepoxides. Previous studies have demonstrated that 1R,2S-dihydroxy-3S,4R,epoxy, 1,2,3,4-tetrahydro-5-MeC (5-MeC-1R,2S-diol-3S,4R-epoxide) is a potent lung tumorigen while the corresponding diol-epoxide of 6-MeC had no effect in newborn mice. From the results of the present study, we estimate that at equimolar doses the formation of diolepoxide--DNA adducts from 5-MeC-1R,2S-diol-3S,4R-epoxide would be at least 20-fold greater than from the corresponding diolepoxide of 6-MeC in newborn mouse lung. Thus, the higher tumorigenic activity of 5-MeC-1R,2S-diol-3S,4R-epoxide compared to that of the corresponding diol epoxide of 6-MeC is partially due to its greater extent of DNA damage.

Animals↗
PubMed1991

Nicotine-derived N-nitrosamines (TSNA) and their relevance in tobacco carcinogenesis.

Biochemical studies and bioassays support the concept that the increased risk for cancer of the oral cavity in snuff dippers and cancer of the lung, upper aerodigestive tract, and pancreas in smokers is most likely associated with the exposure to tobacco-specific N-nitrosamines. The doses of TSNA required to induce tumors in the oral cavity in rats and tumors in the lungs of rats and hamsters are comparable to the total doses of TSNA to which a long-term snuff dipper, respectively a cigarette smoker, are exposed over 4 decades. The carcinogenic NNN and NNK are metabolized to highly reactive electrophiles which react with nucleophilic centers of DNA and with proteins. The DNA-adducts are known to cause miscoding which can activate K-ras proto-oncogenes. K-ras oncogenes have been detected in adenocarcinomas of the lung of smokers. TSNA also form globin adducts in the blood of laboratory animals as well as of snuff dippers and smokers. Such adducts are currently being evaluated for their significance as biochemical markers of exposure to TSNA. These biomarkers may also serve as indicators for the possible endogenous formation of TSNA in tobacco chewers and smokers. Additional research needs in TSNA carcinogenesis include the development of modified methods for the reduction of TSNA in tobacco and smoke, inhibition of TSNA carcinogenesis by nutrients and micro-nutrients and the testing of chemopreventive agents.

Animals↗
PubMed1991

Quantification of 4-hydroxy-1-(3-pyridyl)-1-butanone released from human haemoglobin as a dosimeter for exposure to tobacco-specific nitrosamines.

A method was developed to quantify globin adducts of the tobacco-specific nitrosamines 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN). Globin adducts of NNK and NNN release 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) after mild treatment with a base. HPB was analysed as its pentafluorobenzoate by capillary column gas chromatography with detection by negative-ion chemical ionization-mass spectrometry and selected-ion monitoring. The detection limit for HPB-pentafluorobenzoate was approximately 1 fmol/injection. The method was applied to haemoglobin from snuff dippers, smokers and nonsmokers. Adduct levels were highest in snuff dippers (517 +/- 538 fmol HPB per gram haemoglobin), followed by smokers (79 +/- 189 fmol HPB per gram haemoglobin) and nonsmokers (29.3 +/- 25.9 fmol HPB per gram haemoglobin). The method will be useful in assessing the role of tobacco-specific nitrosamines as causes of cancer in smokers and snuff dippers.

Environmental Monitoring↗
PubMed1991

Inhibition of tobacco-specific nitrosamine 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) tumorigenesis with aromatic isothiocyanates.

4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent tobacco-specific carcinogenic nitrosamine. At low doses, it induces primarily lung tumours in mice, hamsters and rats, regardless of the route of administration. Its unique organ specificity and potency suggest its possible role in the high incidence of lung cancer in smokers. The goal of this study was to find agents that would potentially prevent NNK tumorigenesis. Previous results led us to test phenethyl isothiocyanate (PEITC) on NNK tumorigenesis in a two-year bioassay in Fischer 344 rats. The NNK-treated group developed 80% lung tumour incidence, whereas NNK-treated rats fed PEITC diets had only 40% lung tumour incidence. Incidences in other organs were not affected by this treatment. We also tested PEITC in a 16-week, short-term bioassay against NNK-induced lung adenomas in A/J mice. Pretreatment of mice with PEITC by gavage at four daily doses of 5 mumol or 25 mumol reduced the formation of NNK-induced lung adenomas by 70% or 100%, respectively. Interestingly, benzyl isothiocyanate and phenyl isothiocyanate, the lower homologues of PEITC, were inactive in this bioassay. Using a protocol similar to that used in the bioassays, PEITC was shown to decrease DNA methylation by NNK in the lungs of rats and mice and suppress the metabolism of NNK by mouse lung microsomes. These results are consistent with the previous data, suggesting that the inhibition of NNK-induced lung tumour formation by PEITC is a consequence of reduced DNA methylation caused by inhibition of NNK metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

N-nitroso compounds and tobacco-induced cancers in man.

Human exposure to N-nitroso compounds in tobacco products is more intense and widespread than from any other known source. This paper presents evidence that two of these N-nitroso compounds, 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine are involved in causing cancers of the oral cavity, lung, oesophagus and pancreas in tobacco users. The reduction or elimination of these nitrosamines from tobacco products would probably lead to a decrease in the incidence of these cancers.

Carcinogens↗
PubMed1991

Hemoglobin adducts as biomarkers of exposure to and metabolic activation of carcinogenic tobacco-specific nitrosamines.

The carcinogenic tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) form hemoglobin adducts in laboratory animals and humans. These adducts release 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) upon mild base hydrolysis. HPB released from human hemoglobin can be quantified by gas chromatography-mass spectrometry. It is the only available biochemical marker for determination of exposure to, and metabolic activation of, carcinogens present only in tobacco. Levels of HPB were highest in snuff-dippers, followed by smokers and nonsmokers. Large interindividual variations in adduct levels were observed. The relationship between HPB levels in globin and DNA of rats treated with NNK has been investigated in order to aid in interpretation of the data from humans. These studies have provided the initial database for understanding the metabolic activation of tobacco-specific nitrosamines in humans.

Animals↗
PubMed1990

Evaluation of cysteine adduct formation in rat hemoglobin by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and related compounds.

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) forms hemoglobin adducts in rats. Upon mild base treatment, 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB) is released from this globin. HPB has been suggested as a dosimeter for exposure to and metabolic activation of tobacco-specific nitrosamines. The purpose of this study was 2-fold: (a) to determine whether cysteine adducts of NNK were precursors to HPB, and (b) to determine to what extent cysteine adducts accounted for the material bound to globin that is not released upon mild base hydrolysis. The chemistry of cysteine adduct formation was investigated by reacting N-acetyl-L-cysteine with three model compounds for pyridyloxobutylation by metabolically activated NNK: 4-(carbethoxynitrosamino)-1-(3-pyridyl)-1-butanone (1); 4-oxo-4-(3-pyridyl)-1-butylmethanesulfonate (2); and 4-iodo-1-(3-pyridyl)-1-butanone (3). Five adducts were isolated and characterized by their spectral properties and by independent syntheses: two diastereomers of N-acetyl-S-[1-methyl-3-oxo-3-(3-pyridyl)propyl]-L-cysteine (7a,b), N-acetyl-S-[4-oxo-4-(3-pyridyl)-1-butyl]-L-cysteine (9), and two diastereomers of N-acetyl-S-(2-[2-(3-pyridyl)]-2,3,4,5-tetrahydrofuranyl)-L-cystein e (11a,b). Only 11a,b produced HPB upon mild base treatment; however, the chemistry of this adduct did not support its role as a major precursor to HPB released upon base treatment of globin. The formation of adducts in rat hemoglobin was then examined by reacting it with tritium-labeled 1 [( 5-3H]1) or tritium-labeled 4-oxo-4-(3-pyridyl)-1-butyl p-toluenesulfonate [( 5-3H]4). The results demonstrated that the amino acids corresponding to 7a,b were present in hemoglobin reacted with [5-3H]1, accounting for 72% of the bound tritium. Amino acids corresponding to 9 were not detected in this globin. In contrast, hemoglobin reacted with [5-3H]4 contained the amino acid corresponding to 9 (15% of bound tritium), but not those corresponding to 7a,b. These results indicated that the alpha, beta-unsaturated ketone, 1-(3-pyridyl)-2-buten-1-one (5), played a major role in the hemoglobin binding of 1, but not of 4. Cysteine adducts were not detected in globin isolated from rats treated with [5-3H]NNK. The results of this study provide insights into the mechanisms of cysteine adduct formation in vitro by pryidyloxobutylating agents and indicate that these adducts are not formed in NNK-treated rats.

Animals↗
PubMed1990

Mass spectrometric analysis of tobacco-specific nitrosamine hemoglobin adducts in snuff dippers, smokers, and nonsmokers.

Hemoglobin adducts of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1(3-pyridyl)-1-butanone and N'-nitrosonornicotine were quantified in blood samples collected from snuff dippers, smokers, and nonsmokers. Mild base treatment of hemoglobin adducted by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone or N'-nitrosonornicotine releases 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB). HPB was enriched by solvent partitioning and derivatized to its pentafluorobenzoate. After purification by high performance liquid chromatography, HPB-pentafluorobenzoate was analyzed by capillary column gas chromatography with detection by negative ion chemical ionization mass spectrometry and selected ion monitoring. [4,4-D2]HPB was used as internal standard. The detection limit for HPB-pentafluorobenzoate was approximately 100 amol/injection or 5 fmol/g hemoglobin. Mean adduct levels (fmol HPB/g hemoglobin) were 517 +/- 538 (SD) in snuff dippers, 79.6 +/- 189 in smokers, and 29.3 +/- 25.9 in nonsmokers. Adduct levels in snuff dippers and in a subgroup of smokers were higher than would have been predicted solely based on estimates of exposure to tobacco-specific nitrosamines. The results of this study provide the first measurements of tobacco-specific nitrosamine hemoglobin adducts in humans and suggest new approaches to understanding the metabolic activation of 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone and N'-nitrosonornicotine in humans.

Adult↗