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Biomedical subjects

K Hemminki

Publications and source records attributed to K Hemminki.

At least 289 records · Page 16Linked to original sources
PubMed1993

Development of a 32P-postlabeling assay for 7-methylguanines in human DNA.

The application of a 32P-postlabeling assay for 7-methylguanines in DNA was studied either by labeling the imidazole ring-opened dinucleotide derivatives or by using strong-anion-exchange column chromatography for the adduct enrichment from normal nucleotides. Data showed that 7-methylguanines can be efficiently labeled as dinucleotides when in vitro methylated DNA was first imidazole ring-opened and then digested to the dinucleotide level with deoxyribonuclease I, snake venom phosphodiesterase, and prostatic acid phosphatase. When using ion exchange chromatography for the adduct enrichment, DNA was digested with micrococcal nuclease and spleen phosphodiesterase. Anion exchange chromatography was applied for 7-methylguanine measurements in white blood cell DNA of healthy nonsmokers (n = 17) and patients (n = 4) treated with the methylating drugs procarbazine and decarbazine. We found that the mean level of 7-methylguanine residues in nonsmokers was 2.5 per 10(7) nucleotides. The corresponding level in the patient samples immediately after the drug treatment was 57 per 10(7) nucleotides.

Adult↗
PubMed1993

Seasonal variations in levels of DNA adducts and X-spots in human populations living in different parts of Poland.

White blood cell DNA adducts were measured in coke oven workers, in residents from the area next to the coke oven in Silesia, Poland (highly industrialized region), and in residents from the rural area of Poland using the 32P-postlabeling technique. This method detected aromatic adducts including adducts formed by polycyclic aromatic hydrocarbons (PAHs). Highest levels of adducts in DNA were seen in the group of coke battery workers (6.9 adducts/10(8) nucleotides). Seasonal variations in levels of DNA adducts were observed both in residents of the district near the coke oven area and individuals from the rural area of Poland. Blood samples collected from people living near the coke oven in winter showed much higher levels of DNA adducts than blood samples obtained in summer (5.0 adducts/10(8) nucleotides in winter and 1.4 adducts/10(8) nucleotides in summer). The difference in the level of DNA adducts between winter and summer was smaller in the group of people living in the rural area (3.2 adducts/10(8) and 2.2 adducts/10(8), respectively). In most cases the levels of X-spots correlated with the levels of other DNA adducts. Correlation coefficients(r) between the levels of X-spots and other adducts ranged between 0.46 and 0.74 (p < 0.05), except for coke oven workers where no correlation was observed.

Adult↗
PubMed1993

32P-postlabelling of DNA adducts in styrene oxide-modified DNA and in workers exposed to styrene.

Lamination workers are exposed to large amounts of styrene. A postlabelling method was developed in order to detect DNA adducts in white blood cells from such workers. First, styrene oxide was reacted with DNA, and the adducts were characterized by the nuclease P1 version of the 32P-postlabelling technique. The adducts in human samples were transferred magnetically during chromatography. The 2'-deoxyguanosine 3'-monophosphate (dGMP) adduct standards, including N2 and O6 adducts, were shown to be resistant to the action of nuclease P1. The O6 adducts were detected in the femtomole range at about 10% labelling efficiency. In lamination workers, the level of O6 adducts, adjusted for adduct recovery, was 5/10(8) nucleotides, which was five times the level in controls.

Autoradiography↗
PubMed1993

Testing of quantitative parameters in the 32P-postlabelling method.

The 32P-postlabelling technique involves many steps that need to be carefully controlled in order to obtain a reliable quantitative determination of DNA adducts. We have studied several of the parameters involved in the DNA digestion procedures as well as those concerned in the phosphorylation reaction. Since adducts behave in very different ways in the labelling reaction, an individual protocol has to be worked out for each particular type of adduct. Quantitation is usually possible only if a synthesized standard of the adduct under investigation is run in parallel to the DNA samples throughout the whole procedure.

Adenosine Triphosphate↗
PubMed1992

Molecular and genetic damage in humans from environmental pollution in Poland.

Extreme environmental pollution such as that found in the highly industrialized Silesian region of Poland has been associated with increased risk of cancer and adverse reproductive outcomes. Among the most prevalent carcinogenic and mutagenic air pollutants in Silesia are the polycyclic aromatic hydrocarbons (PAH) which are largely produced by industrial and residential combustion of coal. Molecular epidemiology aims to prevent disease by using biological markers to identify risks well before clinical onset to allow effective intervention. Here, we use a battery of biological markers to measure molecular and genetic damage in peripheral blood samples from residents of Silesia and from persons living in a rural, less polluted area of Poland. The results show that their exposure to environmental pollution is associated with significant increases in carcinogen-DNA adducts (PAH-DNA and aromatic adducts), in sister chromatid exchange including high-frequency cells, and in chromosomal aberrations as well as a doubling in the frequency of ras oncogene overexpression. We found that aromatic adducts on DNA were significantly correlated with chromosomal mutation, providing us with a molecular link between environmental exposure and a genetic alteration relevant to cancer and reproductive risk.

Adult↗
PubMed1992

Magnetic fields of video display terminals and spontaneous abortion.

The aim of this study was to examine whether work with a video display terminal and exposure to the magnetic fields of video display terminals are related to spontaneous abortion. The study was conducted among women employed as bank clerks and clerical workers in three companies in Finland. The cases (191 spontaneous abortions) and controls (394 births) were identified from Finnish medical registers for the years 1975-1985. Use of video display terminals was defined using the workers' own reports and information provided by the companies. The assessment of exposure to the magnetic fields was based on measurements of the fields of video display terminals. The odds ratio for spontaneous abortion for working with video display terminals was not increased (odds ratio = 1.1, 95% confidence interval 0.7-1.6). However, the odds ratio for workers who had used a video display terminal with a high level of extremely low frequency magnetic fields (> 0.9 microT) was 3.4 (95% confidence interval 1.4-8.6) compared with workers using a terminal with a low level of these magnetic fields (< 0.4 microT). Adjustment for ergonomic factors and mental work load factors changed the odds ratio for magnetic field exposure only very slightly. The findings suggest the need for future studies with assessment of exposure to the magnetic fields in the actual working environment to confirm the possible risk.

Abortion, Spontaneous↗
PubMed1992

Serum oncoproteins and growth factors in asbestosis and silicosis patients.

Levels of 9 different oncoproteins and growth factors were assayed by immunoblotting with monoclonal antibodies in 91 serum samples collected between March 1983 and August 1987 from 46 pneumoconiosis patients (36 asbestosis, 10 silicosis) at high risk for the development of cancer. Follow-up of these patients through June 1991 showed that 18 had developed cancer (11 lung, 2 pleural mesothelioma, 2 transitional-cell carcinomas of the urinary bladder, 1 osteosarcoma, 1 non-Hodgkin's lymphoma, 1 adenocarcinoma of the gallbladder). Increased serum levels of ras oncogene-related protein (p21) were found in 7 of the 18 patients who developed cancer (5 lung, 2 pleural mesothelioma) versus 2 of the 28 patients without cancer, a statistically significant difference (p = 0.012). In addition, 6 of the 7 p21-positive cancer cases had positive serum samples prior to clinical diagnosis of disease (average = 16.3 months, range = 3-26 months prior to diagnosis), suggesting that elevated serum p21 levels may be a useful marker for earlier detection in a significant percentage of respiratory malignancies. Finally, elevated serum levels of PDGF-related protein were detected significantly more frequently in advanced pneumoconiosis cases (ILO radiographic classification of 2/1 or greater) than in less advanced cases (80% vs. 41.9%; p = 0.016), and there was a tendency for these PDGF-positive patients to have progression of their disease (68.2% vs. 41.7%; p = 0.065), suggesting that elevated serum PDGF levels may be a marker for the development of severe and progressive pneumoconioses.

Aged↗
PubMed1992

Use of chemical, biochemical, and genetic markers in cancer epidemiology and risk assessment.

New molecular methods have been developed to be used in assessing exposure to and effects of genotoxic and carcinogenic compounds. DNA and protein adducts are measures or surrogates of target dose. Molecular methods are available to probe mutations in oncogenes, antioncogenes, and other specific genes. Furthermore, concentrations of oncoproteins can be determined in biological fluids. If a close link is established between these markers and risk of cancer, they can be used as independent endpoints in the prevention of cancer.

Biomarkers↗
PubMed1992

7-Methylguanine levels in DNA of smokers' and non-smokers' total white blood cells, granulocytes and lymphocytes.

The effect of smoking was investigated on the formation of 7-methylguanines in human peripheral white blood cells. DNA was isolated from total white blood cells, granulocytes and lymphocytes from 10 smokers and 10 non-smokers. 32P-Postlabeling was performed by using anion-exchange chromatography enrichment of adducts. In smokers the mean DNA adduct levels were 6.9, 4.7 and 23.6 7-methylguanine residues/10(7) nucleotides in total white blood cells, granulocytes and lymphocytes respectively. The corresponding values in non-smokers were 3.4, 2.8 and 13.5 adducts/10(7) nucleotides. The mean adduct level was significantly higher in lymphocytes than in total white blood cells or granulocytes both in smokers and in non-smokers. The mean adduct levels differed significantly between smokers and non-smokers.

Adult↗
PubMed1992

Some quantitative considerations about DNA adduct enrichment procedures for 32P-postlabelling.

The concentrations of 2'-deoxyribonucleoside-3'-monophosphates remaining in calf-thymus DNA digests after nuclease P1 digestion or extraction into 1-butanol, the most commonly used adduct enrichment procedures prior to the application of the 32P-postlabelling assay, were measured using HPLC and 32P-postlabelling methods. When 10 micrograms of DNA digested to mononucleotides was used, the total amount of nucleotides remaining in the samples were approximately 4 and approximately 14 pmol after nuclease P1 treatment or 1-butanol extraction respectively. The influence of various concentrations of normal nucleotides on the labelling efficiency of a 2'-deoxyguanosine-3'-monophosphate adduct of benzo[a]pyrene diol-epoxide was also studied and found to depend upon the ratio of normal nucleotides/adducted nucleotides present in the sample. Also, the ATP/normal nucleotides ratio in the phosphorylation reaction may affect the quantitation of the adducts and thus deserves due consideration.

1-Butanol↗
PubMed1992

Determination of malonaldehyde-modified 2'-deoxyguanosine-3'-monophosphate and DNA by 32P-postlabelling.

The 32P-postlabelling assay was used to determine adducts arising upon the reaction of malonaldehyde with 2'-deoxyguanosine-3'-monophosphate. The adducts formed were isolated, structurally characterized and identified as 3-(2-deoxy-beta-D-erythro-pentafuranosyl)pyrimido[1,2-alpha] purin-10(3H)-one. The kinetics of phosphorylation by T4 polynucleotide kinase was studied using 500 fmol of the synthesized standard and found to reach its maximum after 1 h of incubation. A 60% labelling efficiency was obtained at low concentrations of substrate. The adducted substrate was detected at the sub-femtomolar level. Sensitivity of the adducts towards nuclease P1 3'-dephosphorylation was also tested. The same adduct could be detected from calf thymus DNA that had been reacted in vitro with malonaldehyde, and in DNA isolated from mice treated with [14C]malonaldehyde. DNA adducts formed in vitro were isolated after enzymatic digestion to mononucleotides followed by HPLC fractionation or nuclease P1 digestion of normal nucleotides. A combination of the two procedures proved to be the method of choice for the isolation of the malonaldehyde-DNA adducts formed in vivo prior to applying the 32P-postlabelling assay.

Animals↗
PubMed1992

Paternal occupational lead exposure and congenital malformations.

STUDY OBJECTIVE: The aim was to investigate whether occupational exposure to lead in fathers is associated with congenital malformation in their children. DESIGN: The study was a retrospective case-control study, nested within the wives of men biologically monitored for inorganic lead. Information on pregnancy outcome was obtained from medical registers. SUBJECTS: Cases were defined as wives with malformed child during 1973-82. Three age matched controls were selected for each case from the wives who had given birth during 1973-1983. The final study population was 27 cases and 57 controls. MEASUREMENTS AND MAIN RESULTS: Paternal lead exposure was assessed with blood lead measurements and data obtained from a questionnaire. The response rate was 67% among the cases and 76% among the controls. The odds ratio (OR) of congenital malformation for paternal lead exposure was increased (OR 2.4, 95% confidence interval 0.9-6.5), although not reaching statistical significance. The odds ratios varied from 1.9 to 3.2, when adjusted for one potential confounding variable at a time. CONCLUSIONS: Because of the small numbers and low participation, this study offers limited support for the hypothesis that paternal lead exposure is associated with congenital malformation. Further epidemiological studies on the reproductive hazards of paternal lead exposure are needed.

Abnormalities, Drug-Induced↗
PubMed1992

Analysis of deoxyribonucleic acid adducts in workers.

Repeated blood samples were obtained from volunteers who were occupationally exposed to polycyclic aromatic hydrocarbons in a Finnish iron foundry. Aromatic adducts were determined in white blood cell deoxyribonucleic acid of the subjects with the 32P-postlabeling technique after nuclease P1 treatment and butanol extraction, which showed no major difference. When repeated samples were analyzed, it appeared that the oldest ones displayed the lowest adduct levels, probably due to the instability of the adducts upon storage at -20 degrees C. The workers tended to maintain their adducts at a uniform level, a finding suggesting the contribution of host factors in the control of adduct levels.

DNA↗
PubMed1992

Use of molecular biology techniques in cancer epidemiology.

Biochemical techniques have been applied for years in clinical medicine to unravel disease indicators and mechanisms. The study design, resembling that of a case-referent study, has been to compare diseased and healthy individuals. Conclusive results have been obtained for diseases in which relatively few factors cause high risks. The same study design has been maintained with sophisticated methods of molecular biology, which have revealed many types of deoxyribonucleic acid lesions associated with cancer. It is likely that the relatively simple cross-sectional and case-referent studies require input from epidemiologists to unravel multifactorial etiologies. Longitudinal approaches may be the only alternative with which to evaluate the role and usefulness of the application of molecular biology markers in studies of cancer.

DNA Mutational Analysis↗
PubMed1991

The prospects of the development of the method for monitoring of occupational exposure to some alkylating agents.

DNA-adduct formation, depurination and imidazole ringopening were followed in vitro using styrene oxide, ethyleneimine and dimethyl sulfate. Depurination was found to be about 50 times faster in nucleosides than in double-stranded DNA. The half-lives of depurination in DNA were 3 times faster for 7-(2-aminoethyl)guanine as compared to 7-methyl- and 7-(2-hydroxy-2-phenylethyl)deoxyguanosine. In neutrally 7-methylguanine was released some 60 times faster than that of guanine and adenine. This apparent discrepancy in depurination between alkylated and intact bases suggests the possibility of developing a sensitive method for monitoring of DNA alkylations formed by electrophillic chemicals, which might be based on labelling of apurinic sites and utilized for in vivo studies as well.

Alkylating Agents↗