Biomedical subjects

K Randerath

Publications and source records attributed to K Randerath.

At least 91 records · Page 5Linked to original sources

PubMed1990

Aromatic DNA adducts in white blood cells of coke workers.

White blood cell DNA adducts were measured in coke workers, local controls and countryside controls using the 32P-postlabelling technique. The method detected aromatic adducts including those formed by polycyclic aromatic hydrocarbons (PAHs). Coke workers are heavily exposed to PAHs particularly when working at the batteries. A difference in adduct levels was noted between the coke workers at the battery as compared to other jobs. The adduct levels in the non-battery were higher than those in the countryside controls.

Air Pollutants, Occupational↗

PubMed1990

Acute and long-term effects of carbon tetrachloride on DNA modifications (I-compounds) in male mouse liver.

I-compounds are recently discovered species and tissue dependent covalent DNA modifications which are detectable by the 32P-postlabeling assay for DNA adducts and tend to increase with the animal's age. The effects of the hepatocarcinogen carbon tetrachloride (CCl4) on hepatic I-compounds were studied in 10-12-month-old male ICR mice using the 32P-postlabeling assay. CCl4 was dissolved in corn oil (20%, v/v) and intraperitoneally (i.p.) injected in doses of 0.75 ml/kg (0.375 ml/100 g body weight, 20% CCl4 in corn oil) while control mice received corn oil only (0.375 ml/100 g body wt). Twenty-four h after a single injection of CCl4, the intensity of non-polar I-spots in liver DNA was significantly increased as compared with corn oil treated controls, while the level of one polar I-compound was reduced at 24 h. DNA synthesis (as indicated by [3H]thymidine incorporation) was not significantly affected at 24 h after a single dose of CCl4. To study the long-term effects of CCl4, five groups of mice were given two consecutive weekly injections of 0.75 ml/kg CCl4 (as above) and were sacrificed 1, 4, 8, 12 and 22 weeks after the second treatment. In these groups the total liver I-compound levels were reduced to 17.3-49.0% compared with corresponding controls. The maximum decline was observed at 4 weeks (17.3% of control). Comparison of thymidine incorporation showed no significant increase between control and treated liver DNAs at 1, 4 and 8 weeks after CCl4, suggesting that the decrease in I-compound levels was probably not a secondary effect of increased DNA synthesis during postnecrotic proliferation. Even though there was a trend of recovery between 8 and 22 weeks, I-compound levels still remained significantly lower at 22 weeks (49.0%). Since I-compounds appear to be normal DNA modifications, the results suggest that persistent reduction of I-compound levels contributes to the hepatocarcinogenic effect of CCl4.

Age Factors↗

PubMed1990

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on I-compounds in hepatic DNA of Sprague-Dawley rats: sex-specific effects and structure-activity relationships.

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds on the specific patterns of age-dependent I-compound DNA adducts in the liver of male and female Sprague-Dawley rats were determined by the 32P-postlabeling assay. In female rats, TCDD causes a dose-dependent decrease of several individual and total hepatic I-compound levels after administration of 1 and 5 micrograms/kg per week for 4 weeks. In contrast, no such effects were observed in male Sprague-Dawley rats treated with the 5 micrograms/kg dose level of TCDD. The relative effects of TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PCDD) and 1,2,4,7,8-PCDD on hepatic I-compound levels in the susceptible female Sprague-Dawley rats were determined using a dose of 5 micrograms/kg per week for 4 weeks. The two compounds which are substituted in all four lateral positions, namely TCDD and 1,2,3,7,8-PCDD, caused a significant decrease in hepatic I-compound levels, whereas 1,2,4,7,8-PCDD which is substituted in only three lateral positions was inactive. The structure-activity relationships observed for the effects of these compounds on hepatic I-compounds correlated with their corresponding structure-Ah receptor binding and structure-toxicity relationships. The results are therefore consistent with a role for the Ah receptor in the TCDD-mediated reduction in hepatic I-compound levels in female Sprague-Dawley rats. These results and data from previous studies demonstrate a correlation between the susceptibility of an organ/species to the carcinogenic effects of TCDD and the reduction of I-compound levels. The significance of this correlation in the development of TCDD-induced carcinogenesis has not been delineated.

Age Factors↗

PubMed1990

Age-related DNA modifications (I-compounds): modulation by physiological and pathological processes.

I-compounds are covalent DNA modifications that can be detected and measured by 32P-postlabeling assay because of their DNA-adduct like properties. They accumulate in an age-dependent, highly reproducible manner in tissue DNA of untreated animals in the absence of exogenous carcinogens and, therefore, appear to arise via the interaction of DNA with endogenous reactants formed in the course of normal metabolism. Chromatographically, they exhibit a wide range of polarities, indicative of structural diversity. In addition to age-dependent increases, I-compound profiles exhibit prominent species-, sex-, tissue- and diet-dependent qualitative and quantitative differences. Natural-ingredient (chow) diets produce qualitative differences as well as substantially higher I-compound levels in rat liver and kidney, when compared with purified diets. Modified purified diets containing high carbohydrate, protein, or fat concentrations further modulate I-compound profiles. During liver regeneration, I-compounds behave like DNA adducts rather than m5 C in that their levels are not quickly restored. Treatment of rats with the hepatocarcinogens 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), CCl4, and peroxisome proliferators as well as with a choline-devoid hepatocarcinogenic diet depressed the age-related increases of I-compound levels in liver, the target organ. Additional 32P-labeled derivatives were observed only with the peroxisome proliferators and presumably represent DNA adducts of exogenous origin. No I-compounds were detected in a series of Morris hepatomas with different degrees of differentiation. Thus, loss of I-compounds may be associated with altered gene expression/dedifferentiation. On the other hand, the age-dependent accumulation of I-compounds and their adduct-like character suggest potential relations to aging-associated dysdifferentiation and initiation of cancer. Structural complexity indicates different biological roles of I-compounds.

Aging↗

PubMed1990

A comparison of DNA adduct formation in white blood cells and internal organs of mice exposed to benzo[a]pyrene, dibenzo[c,g]carbazole, safrole and cigarette smoke condensate.

Measurement of tissue/cell DNA adducts represents a suitable monitor of carcinogen exposure because the majority of chemical mutagens/carcinogens react with DNA, forming covalent adducts, a key event in the initiation of chemical carcinogenesis. Investigations of DNA-adduct formation in vivo in white blood cells (WBC) versus target tissues, i.e. internal organs for most carcinogens, is expected to yield useful information about the suitability of WBC for biomonitoring and risk assessment. For this purpose, female ICR mice were given 0.4 mmole/kg benzo[a]pyrene (BP), 0.045 mmole/kg dibenzo[c,g]carbazole (DBC) or 2.47 mmole/kg safrole by oral gavage or 4 daily doses (equivalent to 3 cigarettes) of cigarette-smoke condensate (CSC) by topical application. At 24 h after dosing, DNA adducts were detected by a nuclease P1-enhanced 32P-postlabeling assay [M.V. Reddy and K. Randerath, Carcinogenesis, 7 (1986) 1543] in WBC and internal tissues treated with individual carcinogens, while CSC treatment elicited aromatic adducts in most tissues but not in WBC. Adduct patterns of WBC DNA were qualitatively similar to those of internal organs, but adduct amounts varied. BP, a systemic carcinogen, bound nearly as much to WBC DNA as to target-tissue DNA samples; whereas the liver carcinogens, DBC and safrole, bound to WBC DNA considerably less (22- and 51-fold, respectively) compared with liver DNA. The number of adducts in 10(7) nucleotides of WBC, liver, lung, kidney and spleen DNA, respectively, were: 2, 5, 3, 2 and 3 with BP; 6, 131, 6, 14 and 4 with DBC; 5, 238, 3, 5 and 0.6 with safrole. For CSC, these values were 0, 1 and 0.02 in WBC, lung and spleen, respectively. Our results show that carcinogen binding to WBC DNA does not reflect binding to target-tissue DNA in a quantitative sense for the carcinogens studied except for BP, and that WBC are not suitable surrogates for monitoring CSC exposure by DNA-adduct measurement after topical application. The CSC data in mice was consistent with the previous findings in humans that smokers' tissues but not WBC show smoking-related bulky/aromatic DNA adducts, as measured by 32P-postlabeling.

Animals↗

PubMed1990

Age-dependent covalent DNA alterations (I-compounds) in rat liver mitochondrial DNA.

Rat liver mitochondrial (mt) DNA was investigated for the presence of I-compounds, a recently discovered type of DNA modifications which is detected and measured via 32P-postlabeling. These DNA modifications were previously shown to accumulate in an age-dependent manner in total cellular DNA of various tissues of untreated rodents. In the present work, mt DNA of 1-, 3-, 6-, and 9-month-old female Sprague-Dawley rats was found by 32P-postlabeling also to contain I-compounds that increase with age. Most of the I-compounds were identical for mt and nuclear (nu) DNA. A cluster of 2 non-polar I-spots (termed M-compounds) was mitochondria-specific and increased about 8-fold from 1 to 9 months, attaining a RAL value of 44 X 10(-9) or 1 modification in 2.3 X 10(7) DNA nucleotides at 9 months. Quantitative differences between chromatographically identical spots were seen mainly for a low-polarity fraction of I-compounds, which exhibited 2 times higher overall levels in mt DNA versus nu DNA over the age range studied. Total I-compound levels increased during this time 6.9- and 5.1-fold in nuclei and mitochondria, respectively. The M-compound level was close to 10% of total mt DNA I-compound levels. M-compounds may conceivably be derived from potentially DNA-reactive electron carriers of the mt electron-transport chain, while I-compounds common to both mt and nu DNA presumably originate in extramitochondrial sources. The similarity of mitochondrial and nuclear I-compound profiles and amounts implies possible regulatory mechanisms in I-compound formation and repair. Mt DNA maps showed additional 32P-labeled material which may have been associated with DNA damage caused by oxygen free radicals known to be generated by the mt electron-transport chain. Age-dependent increases of mt DNA modifications are potentially related to mt mutations and may be linked to age-related degenerative changes in mitochondria.

Aging↗

PubMed1990

High-resolution TLC mapping and characterization of 32P-postlabeled monophosphate 7,12-dimethylbenz[a]anthracene-DNA adducts.

Previous work has shown that 7,12-dimethylbenz[a]anthracene (DMBA)-DNA adducts can be converted by 32P-postlabeling to different types of radiolabeled derivatives (nucleoside 3',5'-bisphosphates, nucleoside 5'-monophosphates and dinucleotides), and that the 32P-labeled 3',5'-bisphosphate derivatives can be further characterized by cross-referencing with 3H-labeled nucleoside DMBA adducts, for which structural information is available. This work has now been extended by TLC comparisons of 5'-monophosphate and 3',5'-bisphosphate DMBA adducts. To this end, DMBA-modified DNA was enzymatically hydrolyzed to 3'-monophosphates (Xp + Np) or to dinucleotides (XpN), and these digestion products were 32P-postlabeled by published procedures to yield 3',5'-bisphosphate (*pXp) or 5'-monophosphate (*pX) adducts. Individual *pXp and *pX fractions were isolated from polyethyleneimine (PEI)-cellulose TLC maps and chromatographically compared after enzymatic 3'-dephosphorylations of the 3',5'-bisphosphate (*pXp) derivatives (*pXp----*pX + Pi). Four reactions were standardized and employed for this purpose: (i) 3'-dephosphorylation by extensive digestion with nuclease P1; (ii) 3'-dephosphorylation catalyzed by polynucleotide kinase; (iii) partial dephosphorylation by bacterial alkaline phosphatase; and (iv) partial dephosphorylation by prostatic acid phosphatase. Individual DMBA adducts displayed marked differences with regard to their susceptibility to enzymatic dephosphorylation. The three major and most minor postlabeled 5'-monophosphate DMBA adducts were cross-referenced this way with 3',5'-bisphosphate and nucleoside adducts, so that specific dihydrodiol epoxide-nucleoside 5'-monophosphate adducts can now be identified and measured by 32P-postlabeling.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1990

Species and tissue specificities of I-compounds as contrasted with carcinogen adducts in liver, kidney and skin DNA of Sprague-Dawley rats, ICR mice and Syrian hamsters.

I-compounds are age-related bulky DNA modifications that are detected in untreated animals by 32P-postlabeling. To characterize their properties, I-compounds were compared with carcinogen-DNA adducts in liver, kidney and skin of three rodent species. Weanling female Sprague-Dawley rats, ICR mice and Syrian hamsters were fed Teklad LM485 chow diet for 3 months and raised concurrently and strictly under the same environmental conditions. Animals of each species were treated topically with 24 mumol/kg dibenz[a,j]acridine per day for 3 days, then by gavage once with a mixture of safrole and 7,12-dimethylbenz[a]anthracene (60 and 80 mumol/kg respectively), or with one of the individual carcinogens. Liver, kidney and skin DNA from carcinogen-exposed (24 h after treatment) and unexposed animals was analyzed by the monophosphate version of the 32P-postlabeling assay. While each of the three carcinogens produced qualitatively identical major adduct patterns in all samples examined, I-compounds in untreated animals showed distinct species- and tissue-dependent profiles. Rats displayed the highest I-compound levels but the lowest adduct levels in both liver and kidney among the three species. These findings demonstrate fundamental differences between I-compounds and carcinogen-DNA adducts, and support the hypothesis that I-compound formation is primarily related to species-specific, i.e. genetically determined, normal metabolic activities rather than exposure to environmental genotoxic carcinogens.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1990

Strain differences of I-compounds in relation to organ sites of spontaneous tumorigenesis and non-neoplastic renal disease in mice.

Possible associations between the patterns and levels of I-compounds (putative endogenous, age-dependent, adduct-like DNA derivatives) and the incidence of spontaneous tumors and renal diseases in mice were investigated by 32P-postlabeling assay. Liver, lung and kidney DNAs of 8-10 month old inbred male mice of strains C57BL, C3H, CBA, A and RFM were examined. It was found that liver DNA of the C3H mouse, known to develop a high incidence of spontaneous hepatomas, and lung DNA of the A mouse, known to have a high incidence of spontaneous lung tumors, contained smaller numbers and significantly lower total levels of I-compounds as compared with the resistant C57BL mouse. Kidney DNA of C57BL, C3H and A mice presented significantly higher levels of I-compounds compared with those of CBA and RFM mice, both of which are known for exceptionally high incidences of spontaneous renal diseases. Total kidney I-compound levels in CBA and RFM mice were only 30-40% of those found in C3H, A and C57BL. Reduced I-compound levels observed in the three organs thus tended to be associated with spontaneous tumorigenesis and degenerative disease in susceptible strains, suggesting that I-compounds may be important for normal gene transcription and DNA replication. On the other hand, some of these DNA derivatives may, as adduct-like premutagenic lesions, contribute to spontaneous tumorigenesis. This was suggested by the finding that CBA mice which exhibit moderate spontaneous hepatoma incidence, had higher levels of certain I-compounds in their liver DNA although the total levels were not significantly different compared with those in C57BL mice. The observations of the present study suggest that (i) the patterns and levels of I-compounds are genetically determined and (ii) lack or excess of these DNA modifications may result in adverse health effects; however, this may not always be the case, for example, if modulating factors exist which compensate for I-compound deficiency.

Age Factors↗

PubMed1990

Lack of I-compounds in DNA from a spectrum of Morris hepatomas.

A partial, progressive loss of I-compounds (age-dependent, putative indigenous DNA modifications) has been observed recently during hepatocarcinogenesis induced in rats by 2,3,7,8-tetrachlorodibenzo-p-dioxin, choline-devoid diet or peroxisome proliferators. It was of interest, therefore, to investigate the status of I-compounds in hepatic neoplasms. I-compounds were measured by 32P-postlabeling in eight transplantable rat (Morris) hepatomas of different growth rates and in host liver. Most I-compounds seen in liver were not detected in any of the hepatomas, and those present exhibited low levels. Hepatomas displayed an overall level of one I-compound in 2 x 10(8) DNA nucleotides, which was 7-16 times lower than liver values. The extent of I-compound deficiency did not correlate with tumor growth rate. These results, taken together with previously documented pronounced tissue-, sex-, strain- and species-specificity of I-compound profiles, suggest that I-compounds are normal DNA modifications and that their deficiency may contribute to development and maintenance of neoplasia.

Aging↗

PubMed1990

DNA adducts in human environmentally exposed to aromatic compounds in an industrial area of Poland.

The effect of environmental pollution on DNA adducts in humans was analysed in a highly industrialized area of Poland. Coded samples of white blood cell DNA were analysed by 32P-postlabelling and immunoassay from three populations: coke workers, exposed occupationally to high levels of polycyclic aromatic hydrocarbons (PAHs); residents of the towns around cokeries (local controls); and residents from rural Poland (countryside controls). Local controls exhibited adduct levels and patterns similar to those of coke workers, while the levels in rural controls were 2-3 times lower. The results, based on coded samples and two different assays, suggest that environmental pollution is likely to contribute to the adduct levels in local controls. Furthermore, the results show that the levels of aromatic adducts in white blood cell DNA do not linearily relate to ambient air levels of PAHs but other sources such as food may be important contributors.

Air Pollutants↗

PubMed1990

Postlabeling and immunoassay analysis of polycyclic aromatic hydrocarbons--adducts of deoxyribonucleic acid in white blood cells of foundry workers.

Blood samples were obtained from volunteers who were occupationally exposed to polycyclic aromatic hydrocarbons in a Finnish iron foundry and from referents not known to be occupationally exposed to this class of chemical carcinogens. Aromatic adducts were determined in the deoxyribonucleic acid of white blood cells from the exposed workers with the 32P-postlabeling and immunologic techniques. There was a correlation between the estimated exposure in a particular job and the adduct levels. Jobs of men with high adduct levels (greater than 1 adduct/10(7) nucleotides in the postlabeling assay) included sand preparation, molding, shake-out, and transport. The adduct levels were low in men in pattern making, melting, and fettling. This study suggests that 32P-postlabeling and immunoassay may be useful in monitoring human exposure to known and previously unidentified environmental genotoxic agents.

Benzo(a)pyrene↗

PubMed1990

Monitoring carcinogen actions on DNA by 32P-postlabeling.

Among several recently developed analytical methods, 32P-postlabeling analysis is a highly sensitive method for the detection and measurement of covalent carcinogen-DNA adducts and other DNA modifications. Since the method does not require radioactive carcinogens, it is suitable for DNA of humans exposed to environmental or occupational genotoxicants. The basic procedure entails the enzymatic incorporation of 32P-label into monomeric or dimeric hydrolysis products of DNA, followed by chromatographic mapping and autoradiography of the 32P-labeled digestion products and quantitation by scintillation spectrometry. Microgram amounts of DNA are analyzed; thus the assay is well suited for limited amounts of cells or tissue. Various versions of the assay afford different sensitivities of adduct detection. Under optimal conditions, one aromatic or bulky/hydrophobic adduct in 10(8)-10(10) nucleotides can be detected and measured (corresponding to 0.3-30 amol adduct/microgram DNA or 0.1-10 nmol adduct/mol DNA-P). The assay has been successfully applied to a variety of mutagenic (genotoxic) as well as non-mutagenic carcinogens. In humans, the 32P-postlabeling assay has been applied to DNA specimens from cigarette smokers, iron foundry workers, and coke oven workers. Estimation of total aromatic adduct levels in exposed individuals gave values of 1 adduct in 10(6)-10(8) DNA nucleotides. These values are similar to the total levels of persistent adducts in tissues of animals after exposure to initiating or carcinogenic doses of authentic aromatic genotoxicants. Among the non-mutagenic carcinogens investigated are estrogens, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), choline-devoid diet, carbon tetrachloride, and peroxisome proliferators. In addition, age-dependent DNA modifications (I-compounds) are being detected by 32P-postlabeling in animals that have not been knowingly exposed to mutagens/carcinogens. I-compound profiles and levels are dependent on species, tissue, sex, and diet. Reduced levels of I-compounds have been consistently noted in the target organ of carcinogen-exposed animals and in resulting neoplasms, suggesting that I-compound loss may play a role in carcinogenesis.

Animals↗

PubMed1990

DNA adducts in humans related to occupational and environmental exposure to aromatic compounds.

White blood cell DNA adducts were measured in coke workers, local controls and countryside controls using the 32P-postlabelling technique and immunoassay. The methods detected aromatic adducts, including those formed by polycyclic aromatic hydrocarbons. Coke workers are heavily exposed to aromatic compounds, which are also emitted in large amounts into the environment. The two techniques detected a large difference in adduct levels between the coke workers and the countryside controls. The adduct levels in the local controls were substantially higher than those in the countryside controls. As occupational exposure did not account for such a difference, the data suggest that the source of aromatic adducts in local controls is environmental pollution.

Adult↗

PubMed1989

Effects of route of administration on tissue distribution of DNA adducts in mice: comparison of 7H-dibenzo(c,g)carbazole, benzo(a)pyrene, and 2-acetylaminofluorene.

The environmental pollutant 7H-dibenzo(c,g)carbazole (DBC) has been shown to be a potent carcinogen in various mouse tissues, but displays an unusual degree of hepatocarcinogenicity. We have previously reported that in accord with this activity, mouse liver is the target organ for DBC-DNA binding, with total levels being up to 2700 times greater than in extrahepatic tissues after s.c. administration. To elaborate on this finding, we have directly compared the tissue distribution of DNA damage by three diverse aromatic carcinogens, DBC, benzo(a)pyrene (BP), and 2-acetylaminofluorene (AAF). Following a single topical, p.o., or s.c. administration of 80 mumol/kg of test compound to male BALB/c mice, a 32P-postlabeling assay showed the total number of DBC adducts in liver DNA to be 11-138 times that in kidney, lung, or skin DNA. The degree of hepatic adduction varied as a function of the route of administration, with the highest occurring after topical application and the lowest after s.c. injection. The tissue preference for AAF and BP adducts varied with the route of administration and was much less than for DBC adducts, except that topical application of BP gave DNA adduct levels in skin that were 91-218 times greater than in other tissues. For a given tissue and route of administration, DNA adduction by DBC was 1.7- to 950-fold greater than that by BP and AAF, except in skin where the level of DNA adducts from BP was 3 to 4 times that from DBC. We conclude that (a) DBC exhibits an exceptional and unique preference for liver DNA adduction after different routes of administration; (b) DBC is more potent overall than BP or AAF in causing tissue DNA damage; and (c) for each of the three carcinogens, the route of exposure is a much less important factor than the nature of the carcinogen in determining the tissue distribution of covalent DNA damage.

2-Acetylaminofluorene↗

PubMed1989

32P-postlabeling assay for carcinogen-DNA adducts and other dna modifications.

32P-postlabeling analysis is a recently developed, highly sensitive method for the detection and measurement of covalent DNA adducts. Since the method does not require radioactive carcinogens, it is suitable for DNA of humans exposed to environmental or occupational genotoxicants. The basic procedure entails the enzymatic incorporation of 32P-label into enzymatic digestion products of DNA, the chromatographic separation and autoradiographic detection of the 32P-labeled digestion products and their quantitation by scintillation counting. Since only microgram amounts of DNA are required, the assay is well suited for the analysis of DNA lesions whenever only limited amounts of cells or tissue may be available. Various versions of the assay have been described affording different sensitivities of adduct detection. Under optimal conditions, one aromatic or bulky/hydrophobic adduct in 10(8) - 10(10) nucleotides can be detected and measured (this corresponds to 0.0003 - 0.03 fmol adduct/microgram DNA or 0.1 - 10 nmol adduct/mol DNA-P). The assay has been successfully applied to a variety of mutagenic (genotoxic) as well as non-mutagenic carcinogens. Among the latter are estrogens and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In addition, the assay detects age-dependent DNA modifications (I-compounds) in animals that have not been knowingly exposed to mutagens/carcinogens. In humans, the 32P-postlabeling assay has been applied to cigarette smokers, iron foundry workers and coke oven workers. Estimation of total aromatic adduct levels in exposed individuals gave values of 1 adduct in 10(6) - 10(8) DNA nucleotides. These values are similar to the total levels of persistent adducts in tissues of animals after exposure to initiating or carcinogenic doses of authentic aromatic geno-toxicants.

Aging↗

PubMed1989

Covalent DNA damage in tissues of cigarette smokers as determined by 32P-postlabeling assay.

Covalent DNA addition products (adducts) formed by the reaction of chemical carcinogens or their metabolites with DNA are critically involved in the initiation of chemical carcinogenesis and may serve as molecular markers and dosimeters for environmental carcinogen exposures. Using a highly sensitive 32P-postlabeling assay for DNA adduct analysis, we studied DNA damage elicited by cigarette smoke in tissues of smokers. A multitude of characteristic smoking-induced, presumably aromatic DNA adducts were found to occur in a dose- and time-dependent manner in the lung, bronchus, and larynx of smokers with cancer of these organs and to decline only slowly after cessation of smoking. Low levels of adducts appeared to persist for up to 14 years in the lungs of exsmokers with high previous exposures. These results corroborate data of epidemiological studies showing that the lung cancer risk and mortality of smokers increase with the intensity and duration of smoking and decline only slowly after cessation of smoking. Tissue distribution studies in autopsy samples revealed the presence of smoking-associated DNA lesions also in the kidney, bladder, esophagus, heart, ascending aorta, and liver. The most extensive DNA damage was found in lung and heart, i.e., 1 aromatic adduct in about 10(7) DNA nucleotides. Our results suggest that cigarette smoking-induced DNA adduct formation is causally related to cancer in the target organs.

Adult↗

PubMed1989

Interlaboratory comparison of the 32P-postlabelling assay for aromatic DNA adducts in white blood cells of iron foundry workers.

Analysis by nuclease P1-enhanced 32P-postlabelling assay of DNA isolated from the white blood cells of 53 iron foundry workers was carried out independently in 3 laboratories, and the presence of aromatic DNA adducts was detected. The mean adduct levels in foundry workers varied from 9.2 +/- 23 (laboratory 3) and 12 +/- 10 (laboratory 2) to 26 +/- 43 (laboratory 1) and for the controls from 1.7 +/- 0.7 (laboratory 3) to 3.1 +/- 1.7 (laboratory 1) adducts per 10(8) nucleotides. No effect of smoking was observed in the present study. Each laboratory observed large interindividual variations of adduct levels. Good correlations were found between the results of the 32P-postlabelling assays carried out in the 3 laboratories; the correlation coefficients between laboratories 1 and 2, 1 and 3, and 2 and 3 were 0.61, 0.62, and 0.45, respectively, all being statistically highly significant (p less than 0.01). This interlaboratory comparison of the 32P-postlabelling method indicates the reproducibility of the method and its applicability in occupational exposure monitoring.

Chromatography, Thin Layer↗