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S R Tannenbaum

Publications and source records attributed to S R Tannenbaum.

At least 109 records · Page 6Linked to original sources
PubMed1990

Haemoglobin adducts formed by aromatic amines in smokers: sources of inter-individual variability.

In a previous study we found that aromatic amines, particularly 4-aminobiphenyl, formed haemoglobin adducts at higher concentrations in the blood of smokers compared to non-smokers. We re-analyse here data on haemoglobin adducts of 14 aromatic amines in order to ascertain if the inter-individual variability left unexplained by tobacco smoking could be attributed to differences in individual metabolic patterns. For this purpose we computed residuals from analysis of variance in order to adjust for individual smoking habits (type and amount of tobacco). Residuals were correlated within two clearly distinct groups: one formed by binuclear compounds (4-aminobiphenyl, 3-aminobiphenyl and 2-naphthylamine) and the other formed by all other (i.e. mononuclear) compounds. Within each group, highly statistically significant correlation coefficients were found, whereas compounds belonging to one group were not correlated to compounds in the other group. These results can be interpreted as a suggestion that two different metabolic pathways exist, one for binuclear and one for mononuclear arylamines, and that inter-individual differences in such pathways can explain part of inter-individual variability in adduct levels. This interpretation is consistent with recent animal experiments suggesting that there are different enzyme systems for the two classes of compounds.

2-Naphthylamine↗
PubMed1990

The determination of urinary 3-methyladenine by immunoaffinity chromatography-monoclonal antibody-based ELISA: use in human biomonitoring studies.

A mouse monoclonal antibody (Mab) was prepared which showed high specificity for a potential marker of exposure to methylating carcinogens such as 3-methyladenine (3-MeAde). In a low-temperature (4 degrees C) ELISA a linear calibration curve was obtained between 3 and 50 fmol/well. In combination with an immunoaffinity (IA) column prepared from a 3-MeAde rabbit antiserum, the ELISA was used to determine 3-MeAde in urine. The IA-ELISA method was validated by comparison with results obtained by an IA-GC-MS method. The effect of consuming a low 3-MeAde diet on urinary 3-MeAde excretion was investigated in a human volunteer. Urine collected during a 'normal' diet exhibited the characteristic variation in 3-MeAde levels previously observed (9.5 micrograms/24 h, SD = 4.4, n = 5). In contrast, 3-MeAde excretion was markedly lower and less variable on days when the diet was closely controlled (0.63 microgram/24 h, SD = 0.08, n = 3). Dietary intake of 3-MeAde on the latter days was between 0.37 and 0.43 microgram/day, indicating that most, if not all, of the 3-MeAde seen in previous experiments was derived from the diet. The origin of dietary 3-MeAde is not known, but may be related to fumigant use. Dietary manipulation affords the possibility of carrying out model studies, in volunteers, on 3-MeAde intake and formation in vivo.

Adenine↗
PubMed1990

Protein adducts in the molecular dosimetry of chemical carcinogens.

Genotoxic carcinogens form covalent bonds with proteins as well as with DNA. The adducts which result are useful for assessing exposure to the carcinogen, determining inter-individual differences in metabolism and other carcinogen processing, and perhaps in risk assessment. This commentary reviews the development of molecular dosimetry based on protein adducts and describes some of the principles involved. Also described are studies of the binding of bulky lipophilic carcinogens to proteins, which clearly indicate that a high degree of specificity is characteristic of many carcinogen-protein interactions. Studies which have been conducted with human populations are summarized and some proposals for future studies are made.

Aflatoxins↗
PubMed1990

Nitrate biosynthesis in rats, ferrets and humans. Precursor studies with L-arginine.

L-Arginine, the primary nitrogen source for nitric oxide synthesized by many cell types in culture and for biosynthesized nitrate in humans, is also a nitrogen source for biosynthesized nitrate in rats and ferrets. After administration of [15N2]L-arginine to rats and ferrets, [15N]NO3- was detected in urine. Escherichia coli lipopolysaccharide induced more than a 10-fold increase in urinary nitrate in rats and a parallel increase in incorporation of 15N from [15N2]L-arginine into NO3-. Bradykinin, a vasodilator which induces nitric oxide production by endothelial cells in vitro, lacked detectable effect on urinary nitrate or on incorporation of L-arginine nitrogen into nitrate in rats. A prolonged period of vasodilation brought on by an extended period of exercise increased urinary nitrate 2-fold in human subjects. In the rat, recoveries in 24 h post-dose urine collections of [15N]NO3- given i.v. and i.p. were 75 and 64% respectively, while in the ferret, recoveries of i.v. and per os [15N]NO3- doses were 49 and 34% respectively. Thus, nitrate synthesized by mammalian cells in vivo would undergo losses similar to those for exogenous nitrate.

Adult↗
PubMed1990

Hemoglobin-carcinogen adducts as molecular biomarkers in epidemiology.

The goal of our work is to determine the exposure of people to the ultimate form of both environmental and endogenous mutagens and carcinogens. The scientific approach is to develop methods of analysis of chemically-defined adducts of protein and DNA. Our research to date has encompassed a wide variety of compounds known or suspected to cause cancer in people: aromatic amines, heterocyclic amines, polycyclic aromatic hydrocarbons (PAH), aflatoxins, N-nitroso compounds, and urethane. The most advanced of those problems is that of aromatic amines in which several different types of studies on human populations have already been completed using hemoglobin (Hb) adducts of 4-amino-biophenyl (ABP) as the biomarker. These studies have revealed a correlation between the level of amine adduct and risk of bladder cancer, and most important, the role of a metabolic polymorphism, the acetylator phenotype, as an important determinant of adduct level. In the case of PAH we have developed a useful human dosimeter based upon release of bay region tetrols from Hb esters. This method is now being applied to analyze the internal dose of benzo[a]pyrene (BaP) diolepoxide and to determine the range of PAH structures subject to conversion to ultimate carcinogenic forms. Together, these studies open the door to a new era in which we will be able to examine the overall influence of metabolic polymorphisms on the internal dose of many carcinogens in individuals.

Amines↗
PubMed1989

L-arginine is a precursor for nitrate biosynthesis in humans.

Nitrogen from L-arginine was incorporated into urinary nitrate in human subjects. Two subjects given an oral dose of [15N2]L-arginine excreted 24 and 17 umol [15N]nitrate/24 hr, respectively, in their urine in the 24 hr period following the dose. This work demonstrates that L-arginine, a nitrogen source for biosynthesized nitrate in cultured cells and research animals, is a precursor for endogenously synthesized nitrate in humans.

Arginine↗
PubMed1989

Antibody-antigen binding in organic solvents.

We describe, for the first time, the action of antibodies in anhydrous organic solvents. It has been demonstrated that the binding of a hapten, 4-aminobiphenyl, to the immobilized monoclonal antibody 2E11 is strong and specific not only in water but also in a variety of non-aqueous media. Further, the strength of interaction between antibody and hapten has been related to the hydrophobicity of the solvent: the more hydrophobic the solvent, the weaker the protein-ligand interaction.

Aminobiphenyl Compounds↗
PubMed1989

A rapid method for isolation of human hemoglobin benzo[a]pyrene diol epoxide derived adducts using high performance liquid chromatography.

A method is described to isolate rapidly human hemoglobin-benzo[a]pyrene diol epoxide adducts. A combination of 300 A pore size C4 reversed phase HPLC to effect separation of adducted protein from native protein, and mu-bore C18 reversed phase HPLC to isolate and partially characterize proteolytic peptide adducts (by UV), was used.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1989

Quantitation of methylated hemoglobin via hydrolysis of methyl esters to yield methanol.

Methyl esters formed by methylation of carboxylic acid groups on hemoglobin can be quantitated via GC/MS negative-ion chemical ionization analysis of the pentafluorobenzoate derivative of the methanol released from the hemoglobin upon base hydrolysis. Although the method requires extensive cleanup of extracting solvents because of the ubiquitous presence of trace levels of methanol, it is possible to quantitate adducted hemoglobin at levels as low as 4 ng per gram of hemoglobin using [13C, 2H3]methyl alcohol as the internal standard. In principle this method can be used in humans as a dosimeter for exposure to environmental methylating or alkylating agents.

Animals↗
PubMed1989

Purification of the food-borne carcinogens 2-amino-3-methylimidazo [4,5-f]quinoline and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in heated meat products by immunoaffinity chromatography.

A rapid and simple scheme has been developed for the isolation and purification of two of the major mutagenic heterocyclic amines formed in heated beef products by affinity chromatography using monoclonal antibodies which recognize 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Two cell lines producing IgG antibodies were established following fusion of Sp2 or P3x.63 myeloma cells with spleen cells of immunized BALB/cby mice. The antigen was bovine gamma globulin haptenized with 2-(3-carboxypropylthio)-3-methylimidazo-[4,5-f]quinoline. The antibodies were immobilized on CNBr-activated Sepharose 4B. IQ and MeIQx formed in heated beef products were partially purified by XAD-2 chromatography and then applied to the affinity columns. Purification by affinity chromatography was adequate for subsequent quantitative analysis by HPLC with UV detection. With this purification scheme as little as 1 g of beef extract or 15 g of fried beef could be assayed for IQ and MeIQx at the part per billion level. Both antibodies had similar affinity constants for IQ (9.3 X 10(6) and 6.7 X 10(6) M-1) and for MeIQx (7.1 X 10(5) and 2.7 X 10(5) M-1) and both were suitable for immunoaffinity purification of IQ from complex mixtures. MAb2 could be used as well to selectively remove MeIQx from meat products after partial purification by XAD-2. MAb1, despite having a 3-fold higher affinity than MAb2 for MeIQx, could not be used for affinity chromatography for this mutagen.

Animals↗
PubMed1989

Nitrosation by stimulated macrophages. Inhibitors, enhancers and substrates.

Macrophages and their immortalized cell lines can be activated to form nitrite and nitrate via oxidation of arginine and this is accompanied by the formation of N-nitroso compounds. The mechanism of nitrosamine formation has been investigated through the use of compounds which are known either to inhibit or enhance acid-catalyzed nitrosation. The range of nitrogen acceptors has been expanded to include ureas as well as amines of varying pKa and structure. The results are consistent with a mechanism in which NO is oxidized to N2O3 and N2O4, which are capable of nitrosating amines, but not ureas or amides, at neutral pH. This is in agreement with a recent observation that macrophage cell-free extracts can oxidize arginine to NO. The effect of ascorbic acid on intact activated macrophages is complex since nitrite formation is enhanced over a very wide range of ascorbate concentrations (5-500 microM) while nitrosation is inhibited at ascorbate concentrations greater than 50 microM.

Arginine↗
PubMed1989

Formation of DNA and hemoglobin adducts of fluoranthene after single and multiple exposures.

The dose-dependence of hemoglobin binding as well as distribution of fluoranthene and fluoranthene-DNA adducts in various tissues was characterized in male rats 24 h after a single i.p. injection of [3H]fluoranthene. Formation and distribution of DNA adducts after chronic administration of fluoranthene in the diet was also studied. Fluoranthene-derived radioactivity was widely distributed throughout the animal after a single dose, and excreta contained the greatest amounts of radioactivity at all dose levels. Fluoranthene binding to globin was proportional to dose over the range of 2 nmol/kg to 177 mumol/kg, and the adducted protein was cleared at the same rate as unmodified hemoglobin, indicating that the adducts are stable in vivo. In contrast, fluoranthene-DNA adducts were not present at detectable levels in liver or kidney 24 h after one dose; low levels of adducts were found only in the lung at the highest dose level. Chronic administration of fluoranthene in the diet, however, resulted in DNA adduct formation in most tissues examined, including liver, kidney, lung, small intestine, heart, spleen and lymphocytes; adducts were not detectable in testes DNA. The major fluoranthene-DNA adduct found in rat tissues was identified by its chromatographic similarity to the major fluoranthene adduct formed in vitro using microsomally-activated fluoranthene and calf thymus DNA, previously identified as a reaction product of anti-2,3-dihydroxy-1,10b-epoxy-1,2,3-trihydro-fluoranthene with N2-deoxyguanosine. The unusual stability of this diol epoxide at physiological pH may allow transport of this ultimate DNA-binding metabolite to virtually all tissues. These results demonstrate the applicability of the HPLC-32P-postlabelling procedure to detect and quantify fluoranthene-DNA adducts formed in vivo, and suggest that analysis of these adducts in accessible tissues such as lymphocytes may be a means of assessing chronic, high level exposure to fluoranthene. Our results also indicate that hemoglobin adducts of fluoranthene could be useful dosimeters for detecting short-term or chronic exposure to this compound if a suitable method for their detection were developed.

Administration, Oral↗
PubMed1989

Assessment of dietary nitrate intake by a self-administered questionnaire and by overnight urinary measurement.

The relationship between dietary intake and urinary excretion of nitrate was investigated among 35 male and 24 female graduate students in Boston. The dietary assessment method consisted of a self-administered semi-quantitative food frequency questionnaire currently used for large-scale epidemiological studies. Calculated mean daily nitrate intake was 1.83 mmol for men and 2.96 mmol for women; broccoli and green leafy vegetables accounted for 60% of the total. Urinary measurements involved two overnight specimens with a mean collection time of approximately 13 hours. The ratio of intra-to-inter individual variance in urinary nitrate excretion (lambda) was 1.87. The simple correlation coefficient between intake and excretion of nitrate was found to be 0.20; after correction for the within-person variation by using lambda, the correlation coefficient was 0.28. Adjustment for gender, age and Quetelet's index in multiple regression analyses resulted in a partial correlation coefficient between nitrate intake and excretion of 0.37 (p = 0.005). Correction for within-person variation in urinary excretion increased this partial correlation coefficient between intake and excretion to 0.59 (95% CI = 0.03 to 0.87). These data suggest that a self-administered questionnaire may provide useful information on usual nitrate intake, and indicate the need to pursue this possibility further.

Activity Cycles↗
PubMed1989

Elevated blood levels of carcinogens in passive smokers.

The hypothesis that involuntary exposure to tobacco smoke--passive smoking--results in greater risk of cancer was assessed by measuring the levels of two known carcinogens in the blood of 57 nonsmokers with varying degrees of involuntary exposure, including six heavily exposed bartenders. The concentrations of hemoglobin adducts of 4-aminobiphenyl, a bladder carcinogen, were significantly higher in subjects with confirmed involuntary exposure (plasma cotinine concentrations between 2 and 23 ng/ml) compared with subjects with undetectable levels of cotinine. Similarly, adducts of 3-aminobiphenyl were significantly elevated in subjects with confirmed exposure. The odds of 3-aminobiphenyl adduct levels exceeding 2 pg/g of hemoglobin were 6:7 among the confirmed exposed, compared with the odds of 2:42 among subjects with undetectable cotinine (odds ratio = 18; 95 percent confidence interval = 3.3, 94). The validity of the assay was demonstrated by showing striking declines in adduct levels among quitting smokers.

Adult↗
PubMed1989

Preventive action of vitamin C on nitrosamine formation.

N-Nitroso compounds are known to form endogenously in the human stomach from the precursors nitrite as well as secondary and tertiary amines. Ascorbic acid has been found to be an effective blocking agent for this process of formation of carcinogenic substances, both in vitro and in vivo. The mechanism by which ascorbic acid reacts is chemical in nature and results in the formation of NO and dehydroascorbic acid. Since NO can be recycled in the presence of O2 to form [NO]x, which is capable of additional nitrosation, greater than stoichrometric amounts of ascorbate are required for effective inhibition in vivo. The efficacy of ascorbic acid for inhibition of nitrosamine formation in humans has been demonstrated both clinically and epidemiologically through the use of "Nitrosoproline Test"--of Ohshima and Bartsch.

Ascorbic Acid↗
PubMed1989

Mechanisms of endogenous nitrosation.

Endogenous formation of N-nitroso compounds has been demonstrated in both humans and experimental animals. The extent of this process has been estimated by measurement of urinary N-nitrosoproline and has been shown to be modulated by dietary precursors and inhibitors. It is now also recognized that other (non-gastric) pathways of endogenous nitrosation, including those catalysed by bacteria and mammalian cells, may exist. The mammalian cell catalysed pathway utilizes arginine as a precursor for the nitrosating agent and may occur in macrophages or endothelial cells. The estimated contribution of this pathway to normal basal endogenous nitrosation is approximately 20 nmol of N-nitrosoproline/day.

Animals↗
PubMed1988

Isolation and characterization of the major fluoranthene-hemoglobin adducts formed in vivo in the rat.

The binding of fluoranthene (FA) to hemoglobin was studied both in vitro and in vivo in the rat. The in vitro binding of microsomally activated FA to rat hemoglobin appeared to involve the fluoranthene 2,3-dihydrodiol-1,10b-epoxides. Three classes of hemoglobin adducts were observed in rats chronically administered FA in the diet. Based on high pressure liquid chromatography retention times, UV and mass spectral evidence, and behavior upon cis-diol affinity chromatography, the major class of globin adducts formed in vivo was demonstrated to result from binding of syn and anti isomers of FA 2,3-dihydrodiol-1,10b-epoxides to beta-cysteine-125 of rat hemoglobin. These adducts represented at least 41% of the total binding to globin. A minor class of adducts (12% of the total binding) appeared to involve the binding of an unidentified FA metabolite to the same cysteine residue of the protein. A substantial portion of FA binding to rat hemoglobin in vivo (29%) involved metabolic pathways which were not duplicated by simple in vitro systems. That portion of the binding to globin has not been characterized.

Amino Acid Sequence↗