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Biomedical subjects

K Vistisen

Publications and source records attributed to K Vistisen.

15 recordsLinked to original sources
PubMed1999

Increased urinary excretion of 8-oxo-2'-deoxyguanosine, a biomarker of oxidative DNA damage, in urban bus drivers.

Oxidative damage to DNA could be involved in the increased risk of cancer associated with exposure to polluted urban air, which contains a number of oxidants. CYP1A2 is induced by and metabolizes polyaromatic hydrocarbons (PAH) and aromatic amines and could modify effects of exposure to ambient air pollution. Similarly, DNA repair may be influenced by occupational and other exposures as well as modify the effect of DNA damaging agents. As part of a large investigation of the genotoxic burden to diesel exposed workers in transport sectors we studied oxidative DNA damage in 57 non-smoking bus drivers from the greater Copenhagen area. The drivers were studied on a workday and on a day off work. Comparisons were made between drivers from the central (n=30) and rural/suburban (n=27) areas of Copenhagen. The rate of oxidative DNA damage was estimated from 24 h urinary excretion of 8-oxo-2'-deoxyguanosine (8-oxodG), a repair product of the highly mutagenic oxidation of guanine in DNA or the cellular pool of GTP. CYP1A2 activity was estimated from the urinary excretion of metabolites of dietary caffeine. The DNA repair was estimated by unscheduled DNA synthesis (UDS) in mononuclear cells isolated on the workday. Repeated measures ANOVA and multifactorial ANCOVA with CYP1A2 activity, age and UDS as covariates were used for statistical evaluation. On the workday, the 8-oxodG excretion was 190+/-108 and 146+/-89 pmol/kg 24 h in the bus drivers from central and the suburban/rural areas Copenhagen, respectively (p<0.05). The 8-oxodG excretion was not significantly different between the workday and the day off. CYP1A2 activity was not affected by driving area but was correlated with the 8-oxodG excretion on the workday (r=0.53; p<0.05). UDS was not significantly affected by driving area or correlated with the 8-oxodG excretion. The increased excretion of 8-oxodG in bus drivers from central Copenhagen as compared with drivers from rural/suburban greater Copenhagen suggests that exposure to ambient air pollution causes oxidative damage to DNA. This effect may be modified by the activity of CYP1A2 or a coregulated enzyme.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Semen quality and reproductive hormones before orchiectomy in men with testicular cancer.

PURPOSE: To obtain information about preorchiectomy gonadal function in patients with testicular germ cell cancer to improve the clinical management of fertility and other andrologic aspects in these men. PATIENTS AND METHODS: In group 1, a group of 83 consecutive patients with testicular germ cell cancer (TGCC) investigated before orchiectomy, semen analysis was carried out in 63 patients and hormonal investigations, including measurement of follicle-stimulating hormone, luteinizing hormone (LH), testosterone, estradiol, sex hormone-binding globulin (SHBG), inhibin B, and human chorionic gonadotropin (hCG), in 71 patients. Hormone levels in patients with elevated hCG (n = 41) were analyzed separately. To discriminate between general cancer effects and specific effects associated with TGCC, the same analyses were carried out in a group of 45 consecutive male patients with malignant lymphoma (group 2). Group 3 comprised 141 men employed in a Danish company who served as controls in the comparison of semen parameters. As a control group in hormone investigations, 193 men were selected randomly from the Danish National Personal Register to make up group 4. RESULTS: We found significantly lower sperm concentration (median, 15 x 10(6)/mL; range, 0 to 128 x 10(6)/mL) and total sperm count (median, 29 x 10(6)/mL; range, 0 to 589 x 10(6)) in patients with testicular cancer than in patients with malignant lymphomas (sperm concentration: median, 48 x 10(6)/mL; range, 0.04 to 250 x 10(6)/mL; sperm count: median, 146 x 10(6); range, 0.05 to 418 x 10(6)) (P < .001 and P < .001) and healthy men (sperm concentration: median, 48 x 10(6)/mL; range, 0 to 402 x 10(6)/mL; sperm count: median, 162 x 10(6); range, 0 to 1253 x 10(6)) (P < .001 and P < .001). FSH levels were increased in men with testicular cancer (median, 5.7 IU/L; range, 2.0 to 27 IU/L) compared with both men with malignant lymphomas (median, 3.3 IU/L; range, 1.01 to 12.0 IU/L) and healthy controls (median, 4.1 IU/L; range, 1.04 to 21 IU/L)(P = .001 and P = .007, respectively). Surprisingly, we found significantly lower LH in the group of men with TGCC (median, 3.6 IU/L; range, 1.12 to 11.9 IU/L) than in healthy men (median, 4.7 IU/L; range, 1.3 to 11.9 IU/L) (P = .01). We could not detect any differences between men with testicular cancer and men with malignant lymphomas and healthy men with regard to serum levels of testosterone, SHBG, and estradiol. Men with testicular cancer who had increased hCG levels had significantly lower LH and significantly higher testosterone and estradiol than those without detectable hCG levels. CONCLUSION: Spermatogenesis is already impaired in men with testicular cancer before orchiectomy. Neither local suppression of spermatogenesis by tumor pressure nor a general cancer effect seems to fully explain this impairment. The most likely explanation is preexisting impairment of spermatogenesis in the contralateral testis in men with testicular cancer. The question of whether also a pre-existing Leydig cell dysfunction is present in men with testicular cancer could not be answered in this study because the tumor seems to have a direct effect on the Leydig cells. Men with testicular cancer had low LH values as compared with controls. We speculate that increased intratesticular level of hCG also in men without measurable serum hCG may play a role by exerting LH-like effects on the Leydig cells, causing increased testosterone and estrogen levels and low LH values in the blood.

Adult↗
PubMed1998

Use of tumor lines with selectable markers in assessing the effect on experimental metastases of combination chemotherapy with alkylating agents.

High-dose chemotherapy with a 3-day regimen of cyclophosphamide, cisplatin, and carmustine was used to treat mice bearing experimental lung metastases of mammary tumor cell lines with selectable markers (lines 66cl4 and 4TO7). Cloning of lung cells at various times after treatment revealed a rapid 3 to 4 log loss of clonogenic tumor cells, down to undetectable levels. However, after several weeks, clonogenic tumor cells reappeared in the lungs; few cures were obtained even when mice had a relatively low tumor burden when treated with chemotherapy. Splenocyte numbers and response to Concanavalin A indicated a transient immunosuppression. In one experiment, mice were treated with a second round of chemotherapy 3 weeks after the first. The number of clonogenic cells per lung again dropped, but regrowth of cells was rapid, and no cures were obtained. Inoculation of tumor-bearing mice s.c. after chemotherapy with lethally irradiated cells of the highly immunogenic tumor cell line 4TO7-IL-2 had little effect on the rate of reappearance of line 4TO7 in lungs, but subsequent growth of tumor cells in lungs was slowed. This model system can be used to test the efficacy of additional immunotherapy and chemotherapy regimens on minimal residual metastatic disease after high-dose chemotherapy, when remaining metastatic cells are apparently dormant.

Animals↗
PubMed1998

Oxidative DNA damage in vivo: relationship to age, plasma antioxidants, drug metabolism, glutathione-S-transferase activity and urinary creatinine excretion.

Oxidative DNA modification has been implicated in development of certain cancers and 8-oxodG, the most abundant and mutagenic DNA modification, has for some time been considered a biomarker of this activity. Urinary excretion of 8-oxodG over 24h has been used to estimate the rate of damage to DNA, and animal studies have supported this rationale. Reported determinants include tobacco smoking, heavy exercise, environmental pollution and individual oxygen consumption. Samples from three published studies were used to determine the association of urinary 8-oxodG excretion with age, plasma antioxidants, the glutathione-S-transferase phenotype and the activity of the xenobiotic metabolising enzyme CYP1A2. In the age range 35-65 years, age was not related to urinary 8-oxodG excretion, and there were no relations to either the glutathione-S-transferase phenotype or to the plasma antioxidants: vitamin C, alpha-tocopherol, beta-carotene, lycopene or coenzyme Q10. The activity of CYP1A2 showed a significant correlation in two of the three studies, as well as a significant correlation of 0.26 (p < 0.05) in the pooled data set. Regression analysis of CYP1A2 activity on 8-oxodG indicated that 33% increase in CYP1A2 activity would correspond to a doubling of 8-oxodG excretion. This finding needs to be confirmed in independent experiments. Spot morning urine samples can under certain circumstances be used to estimate 8-oxodG excretion rate provided that creatinine excretion is unchanged (in paired experiments) or comparable (in un-paired experiments), as evaluated from the correlation between 8-oxodG excretion in 24 h urine samples and in morning spot urine samples corrected for creatinine excretion (r = 0.50, p < 0.05). We conclude that 8-oxodG excretion is determined by factors like oxygen consumption and CYP1A2 activity rather than by factors like plasma antioxidant concentrations.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Genotype and phenotype of glutathione S-transferase mu in testicular cancer patients.

The incidence rate of testicular cancer has been steadily increasing during the last 50 years, and only cryptorchidism, i.e. undescended testes, has been identified as an important risk factor. An interplay between changing environmental factors and genetic susceptibility e.g. in foreign compound metabolizing enzymes, may have important influences on the risk. The aim of this study was to investigate if glutathione S-transferase mu (GST mu) deficiency, which in previous studies has been associated with malignant melanoma and cancers of the lung and bladder, is a risk factor of testicular cancer. Three hundred and seventy-eight men participated (80 seminomas, 104 non-seminomas and 194 controls) in a population-based case-control study. The phenotype of GST mu was determined in 366 men by ELISA, the genotype was determined in 324 men by polymerase chain reaction. The concordance between geno- and phenotype was 94.4%. The odds ratio of having the GST mu negative phenotype and testicular cancer was 1.08, (0.72-1.64; 95% confidence interval (CI)), and the odds ratio of having the GSTM1 null genotype and testicular cancer was 1.10; CI95% (0.71-1.70). This study provides no evidence of an association between phenotypically determined GST mu deficiency or GSTM1 null genotype and testicular cancer. The narrow confidence intervals rule out GST mu as a major single risk factor for testicular cancer.

Adult↗
PubMed1996

Dose-dependent inhibition of CYP1A2, CYP2C19 and CYP2D6 by citalopram, fluoxetine, fluvoxamine and paroxetine.

OBJECTIVE: The purpose of this pharmacokinetic study was to investigate the dose-dependent inhibition of model substrates for CYP2D6, CYP2C19 and CYP1A2 by four marketed selective serotonin reuptake inhibitors (SSRIs): citalopram, fluoxetine, fluvoxamine and paroxetine. METHODS: The study was carried out as an in vivo single-dose study including 24 young, healthy men. All volunteers had been identified as sparteine- and mephenytoin-extensive metabolisers. The volunteers received in randomised order, at weekly intervals, increasing single oral doses of one of the four SSRIs, followed 3 h later by sparteine (CYP2D6), mephenytoin (CYP2C19) and caffeine (CYP1A2) tests. Fluoxetine was given at 3-week intervals because of the long half-life of fluoxetine and its metabolite norfluoxetine. Citalopram, fluoxetine and paroxetine were given in doses of 10, 20, 40 and 80 mg and fluvoxamine was given in doses of 25, 50, 100 and 200 mg. RESULTS: With increasing doses, there was a statistically significant increase in the sparteine metabolic ratio (MR) (P < 0.01, Page's test for trend) for all four SSRIs. The increase was modest after intake of citalopram and fluvoxamine, while the increase was more pronounced after fluoxetine intake, although no volunteers changed phenotype from extensive metabolisers to poor metabolisers. Three of the six volunteers changed phenotype from extensive metabolisers to poor metabolisers after intake of 40 or 80 mg paroxetine. There was a statistically significant increase in the mephenytoin S/R ratio (P < 0.01, Page's test for trend) with increasing doses of fluoxetine and fluvoxamine, but not after citalopram and paroxetine. However, no volunteers changed phenotype from extensive to poor metabolisers of S-mephenytoin. After intake of fluvoxamine, the urinary excretion of the metabolites related to N3 demethylation of caffeine were below the limit of quantification, whereas there were no significant changes in the urinary caffeine metabolic ratios after intake of the other three SSRIs. CONCLUSION: This investigation confirms that paroxetine and fluoxetine are potent inhibitors of CYP2D6, that fluvoxamine and fluoxetine are moderate inhibitors of CYP2C19 and that fluvoxamine is a potent inhibitor of CYP1A2 in humans in vivo. The clinical prediction of interaction from single-dose experiments may have to take the degree of accumulation during steady-state after multiple doses into account.

Adult↗
PubMed1996

Extreme exercise and oxidative DNA modification.

Extreme exercise increases oxygen uptake with a potential for increased formation of reactive oxygen species. Damage to biomolecules may occur if such an increase exceeds the protective capacity of antioxidant defence mechanisms. Vigorous exercise amounting to approximately 10 h a day for 30 days increased the rate of oxidative DNA modification by 33% (95% confidence limits, 3-67%; P < 0.02) in 20 men owing to the urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine, an oxidatively modified deoxynucleoside originating from nuclear DNA repair, oxidation of the nucleotide pool from mitochondrial DNA and/or from cell turnover. Oxidative stress to DNA points to a risk for the development of cancer and premature ageing from extreme exercise.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1995

Moclobemide, a substrate of CYP2C19 and an inhibitor of CYP2C19, CYP2D6, and CYP1A2: a panel study.

The reversible monoamine oxidase A inhibitor moclobemide was given in single (300 mg) and multiple doses (600 mg/day) to 11 male and four female healthy volunteers (age range, 23 to 27) who were either poor metabolizers of S-mephenytoin (n = 7) or extensive metabolizers of S-mephenytoin (n = 8). All were extensive metabolizers of sparteine. Poor metabolizers of S-mephenytoin had lower moclobemide clearance values (median, single dose: 16.1 versus 43.2 L.hr-1; steady state: 13.4 versus 22.1 L.hr-1) and longer moclobemide half-life values (median, single dose: 4.0 versus 1.8 hours; steady state: 5.1 versus 2.7 hours) than extensive metabolizers of S-mephenytoin. The plasma levels of a metabolite formed by C-hydroxylation (Ro 12-8095) were lower in poor metabolizers of S-mephenytoin than in extensive metabolizers of S-mephenytoin. Moclobemide thus partially undergoes oxidative metabolism by way of the polymorphic CYP2C19. A combined mephenytoin, sparteine, and caffeine test performed before, during, and after multiple dosing of moclobemide showed changes in the metabolic indexes compatible with a reversible inhibition of oxidation by way of the corresponding CYP enzymes--CYP2C19, CYP2D6, and CYP1A2--during moclobemide treatment.

Adult↗
PubMed1995

Restricted pulmonary diffusion capacity after exercise is not an ARDS-like injury.

Pulmonary diffusion capacity (DLCO) is reduced 2 h after various types of exercise, such as rowing, treadmill running, arm cranking and marathon running. The decrease in DLCO may involve alterations in the alveolar-capillary membrane as well as depletion of the central blood volume. We hypothesized that the reduction in DLCO might also be influenced by oxygen free radicals, acute phase proteins and endotoxin, which are also involved in the adult respiratory distress syndrome (ARDS). Ten competitive male oarsmen performed a 6 min 'all-out' ergometer row. Single breath DLCO was determined before and 2 h after rowing and venous blood samples were also obtained during the row. Absolute DLCO decreased by 11% (range 0-20%) 2 h after rowing, whereas the concentration of endotoxin did not change significantly and interleukin (IL)-1-alpha, IL-8 and tumour necrosis factor (TNF)-alpha were below the levels of detection before, during and 2 h after rowing. Oxygen free radicals were evaluated by oxidative modification of amino acids and DNA. Corrected for creatinine in urine voided 3 h post-exercise, the DNA repair product 8-oxo-7,8-dehydro-2-deoxyguanosine (8-oxodG) did not change significantly. The ratio of fluorescence due to dityrosine to that due to tryptophan in plasma proteins increased after exercise. This might reflect an effect of oxygen free radicals, but it might also indicate an altered relative composition of plasma proteins. These results suggest that the reduced pulmonary diffusion capacity following exercise is unrelated to factors typically associated with ARDS.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1994

Protein studies of human non-Hodgkin's B-lymphoma: appraisal by two-dimensional gel electrophoresis.

We have utilized two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) coupled with silver stain to identify cellular proteins in human non-Hodgkin's B-lymphoma (NHL). Five cell lines (SKDHL2B, WSU-DLCL2, WSU-NHL, WSU-FSCCL and SKLN1), representing four different NHL maturational stages and a normal Epstein-Barr virus (EBV)-transformed line of B-cell origin (SKLN1) were studied. The NHL lines were immunophenotyped using flow cytometry with lineage associated monoclonal antibodies. Whole cell lysates of the cell lines were subjected to 2-D PAGE analyses. The gels were analyzed with an image scanning computer and the qualitative differences of protein patterns were studied. Results revealed great similarities in patterns of the NHL lines. A master map containing common NHL-protein spots was constructed. When the map of each tumor line was compared to the master map, several protein spots were associated with each NHL-grade. Search for these proteins in the normal EBV-transformed B-cell line showed that only one of the proteins (S3; M(r)/pI 19/5.9) was present. Proteins that were detected in malignant NHL, but not in the normal EBV-line, could provide important information regarding the human NHL B-lymphocyte data-bases. Whether or not these proteins are definite malignant markers to distinguish between different NHL maturational stages needs further exploration through electroblotting and microsequencing.

Antigens, CD↗
PubMed1992

Oxidative DNA damage estimated by 8-hydroxydeoxyguanosine excretion in humans: influence of smoking, gender and body mass index.

Oxidative DNA damage may be implicated in ageing, carcinogenesis and other degenerative diseases. Oxidative DNA damage can be assessed in humans in vivo from the urinary excretion of the DNA-repair product 8-hydroxydeoxyguanosine (8OHdG). We investigated factors influencing the excretion of 8OHdG in 24 h urine from 83 randomly selected healthy subjects (52 women) aged 40-64 years. For 2 weeks prior to urine collection the subjects kept a weighed diet record. 8OHdG was quantified by an automatic three-dimensional HPLC analysis with electrochemical detection. The 8OHdG excretion was 252 +/- 103 (mean +/- SD) pmol kg body weight/24 h with a range from 78 to 527. Multiple regression analysis identified three factors, smoking, body mass index (BMI) and gender, as significant predictors of the 8OHdG excretion. In 30 smokers the 8OHdG excretion was 320 +/- 99 pmol/kg/24 h opposed to 213 +/- 84 pmol/kg/24 h in 53 non-smokers. According to multiple regression analysis smokers excreted 50% (31-69%; 95% confidence interval) more 8OHdG than non-smokers. In 52 women the 8OHdG excretion was 240 +/- 106 pmol/kg/24 h opposed to 271 +/- 96 pmol/kg/24 h in 31 men. According to the multiple regression analysis men excreted 29% (10-48%) more 8OHdG than women. According to multiple regression analysis the 8OHdG excretion decreased with 4% (2-6%) per increment in BMI measured in kg/m2. The dietary distribution of energy demonstrated no important predictive value with respect to 8OHdG excretion. The intake of the antioxidant vitamins C and E and of vitamin A equivalents, including beta-carotene, was not associated with 8OHdG excretion. The results suggest that smoking increases oxidative DNA damage by approximately 50%. This effect implies potential serious health effects adding to the other well-known health hazards of smoking. The higher 8OHdG excretion in men and lean subjects may be related to a higher rate of metabolism with increased availability of reactive oxygen species. The apparent 7-fold individual variation in oxidative DNA damage carries implications regarding the rate of ageing and the risk of cancer and other degenerative diseases. The excretion of 8OHdG into urine offers a valuable tool for testing such hypotheses in humans.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1992

Foreign compound metabolism capacity in man measured from metabolites of dietary caffeine.

Caffeine is sequentially metabolized by cytochrome P4501A2 (CYP1A2), N-acetyltransferase (NAT) and/or xanthine oxidase (XO). In the present study the activity of these three enzymes was estimated from ratios of the metabolites formed from dietary caffeine and excreted into the urine collected as spot samples. In the urine samples from 10 out of 377 subjects concentrations of caffeine metabolites were too low to allow reliable measurements of the ratios. In 335 healthy subjects the NAT activity showed a typically bimodal distribution with 47% fast acetylators and 53% slow acetylators, consistent with a Danish population. The ratios reflecting CYP1A2 and XO activities were log normal and normal distributed, respectively. In 103 non-smoking men and 90 non-smoking women the ratio of caffeine metabolites expressing CYP1A2 activity was 4.7 +/- 1.6 and 4.3 +/- 1.9 as compared to 7.8 +/- 2.5 and 7.3 +/- 3.0 in 31 male and 25 female subjects smoking 10 cigarettes/day or more respectively, verifying induction of CYP1A2 by tobacco (P less than 0.05), but minimal sex-related differences. In 12 non-smoking pregnant women and in 28 women using oral contraceptives the CYP1A2 ratio was 29 and 20% reduced respectively (P less than 0.05). In a multivariate analysis the only significant predictor of the XO ratio was the consumption of caffeine with an increase of 2% per cup of coffee or equivalent (P less than 0.05). In 23 healthy male subjects 30 days of vigorous exercise increased the CYP1A2 ratio by 70% and the XO ratio by 42% (P less than 0.05), but left the NAT ratio unchanged. In nine healthy volunteers daily ingestion of 500 g of broccoli for 10 days increased the CYP1A2 ratio by an average of 12% (P less than 0.05), compared to a control period with ingestion of an equivalent weight of non-cruciferous green vegetables. The ratios of metabolites from dietary caffeine in spot urine samples offer ethical, non-invasive and reliable estimates of CYP1A2, NAT and XO. These enzymes are highly relevant for the bioactivation of potentially toxic compounds and the formation of oxygen radicals. The method is applicable in large-scale epidemiological studies, allowing, for example, prospective testing of the relationship between these enzyme activities and the development of disease. Exercise may increase CYP1A2 activity to a magnitude corresponding to heavy smoking, as well as XO by mechanisms that remain to be clarified.

Acetylation↗
PubMedDate not supplied

Protein study of T and B acute lymphoblastic leukemia cell lines.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was used to identify cellular proteins in T and B acute lymphoblastic leukemia (ALL) cell lines. Five lines, REH and BALL-1 of B-cell lineage, CCRF-CEM and HPB-ALL of T-cell lineage, and a normal Epstein-Barr virus (EBV)-transformed line of B-origin (SKLN1) were studied. The lines were immunophenotyped using flow cytometry and lineage associated monoclonal antibodies. Whole cell lysates of the cell lines were subjected to 2-D PAGE analyses. 2-D gels were analyzed with an image scanning computer and the qualitative as well as quantitative differences of the protein patterns were studied. Despite the great similarities in the patterns of the B- and T-gels, three proteins were unique to B-cell lines, while eight were unique to T-cell lines. Using cell lines is the first step toward identifying potential markers in ALL and can provide important information regarding the human ALL databases. Whether these proteins are definite markers for B- or T-ALL or are unique to the cell lines studied needs further exploration.

Algorithms↗
PubMedDate not supplied

8-Hydroxydeoxyguanosine as a urinary biomarker of oxidative DNA damage.

Living organisms are continuously exposed to reactive oxygen species as a consequence of biochemical reactions as well as external factors. Oxidative DNA damage has been implicated in aging, carcinogenesis and other degenerative diseases. The urinary excretion of the DNA repair product 8-hydroxydeoxyguanosine (8OHdG) has been proposed as a noninvasive biomarker of oxidative DNA damage in humans in vivo. We have developed a three-dimensional HPLC analysis with electrochemical detection for the analysis of 8OHdG in urine and studied factors affecting the excretion of this biomarker in 83 healthy humans and in various laboratory animals, including dog, pig, and rat. Previously, other groups have used comparable HPLC methods or gas chromatography-mass spectrometry with selective ion monitoring for measuring the excretion of 8OHdG in humans, rats, mice, and monkeys. In the 169 humans studied so far, the average 8OHdG excretion was 200-300 pmol/kg per 24 h with a sevenfold range, and the coefficient of variation was 30-40%. This excretion corresponds 140-200 oxidative modification of guanine bases per cell per day. Thirty-two smokers from our study population excreted 50% (31-69%; 95% confidence interval) more 8OHdG than 53 nonsmokers. This indicates a 50% increased rate of oxidative DNA damage from smoking, adding to the other well-known health hazards of smoking. The biochemical-physiological basis is unknown but may be related to smoke constituents including or generating reactive oxygen species and/or consuming antioxidants and/or the well-known enhancing effect of smoking on the metabolic rate. In our 83 healthy subjects the 8OHdG excretion correlated with body composition. Thus, lean and/or male subjects excreted more than obese and/or female subjects, possibly related to differences in metabolic rate. In accordance, the excretion of 8OHdG decreased after calorie restriction, which will cause a decline in the metabolic rate. Across the investigated species, humans, dogs, pigs, and rats, the excretion of 8OHdG correlated with the specific metabolic rate, confirming data from other groups on humans, monkeys, rats, and mice. The excretion of 8OHdG decreased with age in rats in parallel with the decline in metabolic rate with advancing age. The excretion of 8OHdG reflects the formation and repair of only one out of approximately 20 described oxidative DNA modifications. So far, methods are not available for the determination of the corresponding repair products, except 8OHdG and thymidine glycol, in urine. Moreover, the importance in terms of mutagenicity, particularly regarding tumour suppressor genes and oncogenes, is mainly documented for 8OHdG in DNA.(ABSTRACT TRUNCATED AT 400 WORDS)

8-Hydroxy-2'-Deoxyguanosine↗