Search PubMed⌕ Search

Biomedical subjects

A Haugen

Publications and source records attributed to A Haugen.

At least 91 records · Page 5Linked to original sources
PubMed1986

Determination of polycyclic aromatic hydrocarbons in the urine, benzo(a)pyrene diol epoxide-DNA adducts in lymphocyte DNA, and antibodies to the adducts in sera from coke oven workers exposed to measured amounts of polycyclic aromatic hydrocarbons in the work atmosphere.

Workers in coke oven plants have a higher incidence of lung cancer than the general population. They are exposed to a variety of chemicals, in particular the polycyclic aromatic hydrocarbons (PAH), including benzo(a)pyrene. To evaluate the genotoxic effects of PAH exposure, air samples and urine samples were analyzed for PAH by capillary gas chromatography and high-performance liquid chromatography, respectively. Since benzo(a)pyrene is activated to 7 beta,8 alpha-dihydroxy-(9 alpha,10 alpha)-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDE) and binds to DNA, we have used ultrasensitive enzymatic radioimmunoassay and synchronous fluorescence spectrophotometry to measure BPDE-DNA adducts in lymphocyte DNA. The results show that workers were exposed to high concentrations of atmospheric PAH. However, the mean PAH exposure levels are reduced 60% when the workers wore masks during work. When compared to exposure levels, the urinary excretion of PAH was relatively low. Approximately one-third of the workers had detectable putative BPDE-DNA adducts in lymphocytes by ultrasensitive enzymatic radioimmunoassay, and 10% of the samples had emission peaks at 379 nm by synchronous fluorescence spectrophotometry. The four most positive samples were the same in both of the assays. Antibodies to an epitope(s) on BPDE-DNA were found in the sera of approximately one-third of the workers. Detection of DNA adducts and antibodies to these adducts are internal indicators of exposure to benzo(a)pyrene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1985

Metabolism and mutagenicity of aromatic amines by human fetal liver.

Human fetal liver microsomes were found to metabolize the carcinogen 2-acetylaminoflurene (AAF), the major metabolite being the deacetylated product 2-aminofluorene (AF). On the other hand, N-hydroxy-2-acetylaminofluorene (N-OH-AAF), a proximate carcinogenic metabolite, could not be detected. The human fetal liver samples converted AF and N-OH-AAF, but not AAF, to products mutagenic for S. typhimurium TA 98.

2-Acetylaminofluorene↗
PubMed1985

Differentiation markers (S-100, GFAP, NSE and D2) in fetal rat brain cells during malignant transformation in cell culture.

Malignant cell lines obtained by ethylnitrosourea (EtNU)-induced transformation of fetal rat brain cells in culture express protein markers of different types of neural cells. These are the nervous system-characteristic S-100 protein; glial fibrillary acidic protein (GFAP); neuron-specific-enolase (NSE), and the D2-cell adhesion molecule. S-100 protein was absent in fetal brain cells in culture, but gradually appeared in the later stages of malignant transformation and further increased at onset of rapid growth of atypical cells (stage IV). GFAP and D2 were weakly expressed in primary fetal brain cells and did not change throughout malignant transformation. NSE was present in both normal and carcinogen-treated fetal brain cells, and increased at later stages of malignant transformation. From stage III (40-100 days) some cultures were strongly positive and some negative, and the same was seen in the resulting tumorigenic cells about 100 days later. In conclusion the stepwise process of malignant transformation of brain cells in culture ended with a stable phenotype of cells capable of expressing varying types of differentiation markers. The presence of these markers in rat brain cells undergoing malignant transformation may indicate that EtNU given at 18th days of gestation is acting on multipotent neuroectodermal cells.

Animals↗
PubMed1985

Identification of phorbol ester binding activity in the particulate and soluble fractions of human fetal tissues.

The presence of specific binding sites for phorbol esters was demonstrated in various human fetal tissues by binding assays of [3H]12-O-tetradecanoylphorbol-13-acetate (TPA) to particulate and cytosol fractions. Maximal binding activity of the soluble receptor is dependent on calcium and phosphatidylserine. Marked differences in receptor levels were found in various human fetal tissues. However, all the tissues tested contained binding sites for TPA. Particulate receptor concentration was highest in the brain, while the cytosolic receptor concentration was high in brain, stomach and liver. Human fetal tissues bound TPA with a Kd between 10 and 30 nM.

Caenorhabditis elegans Proteins↗
PubMed1985

Differential capacities for DNA repair in Clara cells, alveolar type II cells and macrophages of rabbit lung.

The ability to repair damaged DNA was determined in different cell populations of rabbit lung cells isolated by centrifugal elutriation. DNA excision repair, measured as unscheduled DNA synthesis, was examined in in vitro confluent primary cultures. A dose dependent level of DNA excision repair was observed in alveolar type II cells after exposure to the direct acting alkylating agents N-methyl-N'-nitro-N-nitrosoguanidine, N-ethyl-N-nitrosourea and methyl methansesulphonate. Furthermore, O6-alkylguanine-DNA alkyltransferase activity was easily detectable in alveolar type II cells and alveolar macrophages. In contrast, non-ciliated (Clara) cells had 4 to 20-fold lower levels of DNA excision repair and non-detectable levels of O6-alkylguanine-DNA alkyltransferase. Uracil-DNA glycosylase activities in Clara cells and alveolar type II cells were in the same range and had 3-fold lower activity than alveolar macrophages. Our findings indicate that various lung cells differ in DNA repair capacity and may thus differ in sensitivity to some carcinogens.

Animals↗
PubMed1985

An applied synchronous fluorescence spectrophotometric assay to study benzo[a]pyrene-diolepoxide-DNA adducts.

Synchronous scanning fluorescence with a fixed wavelength difference (delta lambda) of 34 nm between excitation and emission was used to quantitate benzo[a]pyrene-diol epoxide (BPDE)-DNA adducts. Fluorescence emission maxima occurred at 382 nm for BPDE-DNA and at 379 nm for benzo[a]pyrene-tetrols and -triol, which are hydrolysis products of BPDE. Similarly, the peak for pyrene was at 372 nm and for 1-nitropyrene at 386 nm. The minimum detectable amount of BPDE-moieties in in vitro modified BPDE-DNA, after hydrolysis in HCl, was 20 fmol in 100 micrograms of DNA, which is equivalent to 1 adduct per 1.4 X 10(7) nucleotides. The correlation of fluorescence intensity and the amount of BPDE-moieties was linear between 20 fmol and 1 pmol. DNA isolated from human lymphoblasts incubated with BPDE had the same fluorescence peak and the correlation between the fluorescence intensity and the amount of BPDE in the incubation mixture was linear. Among the DNA-samples from peripheral blood lymphocytes of 30 aluminum plant workers, only one sample was found to contain a peak similar to BPDE-DNA. None of the DNA-samples from 10 persons not occupationally exposed were positive. Measurement of BPDE-DNA adducts by synchronous fluorescence spectrophotometry should be useful in monitoring human exposure to benzo[a]pyrene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1984

Effects of nickel sulfate on growth and differentiation of normal human bronchial epithelial cells.

Epidemiological studies have shown that inhalation of nickel compounds enhances the risk of human respiratory cancer. Cultures of normal human bronchial epithelial cells were continuously exposed to a dose (5-20 micrograms/ml) of NiSO4 that reduced their colony forming efficiency by 30-80%. After 40 days of incubation, the cultures consisted of large, squamous cells; mitotic cells were not observed. The cells were then maintained in medium without NiSO4. After 40-75 total days of incubation, colonies of mitotic cells appeared at a rate of 1 colony per 100 000 cells originally at risk; no colonies appeared in control cultures or in cultures exposed to less than 5 micrograms NiSO4/ml for 90 days. Twelve NiSO4-altered cell cultures isolated from five experiments have been expanded into mass cultures. Most of the cell lines have an increased population doubling potential (greater than 50 divisions). Some exhibit aberrations in the squamous (terminal) differentiation process whereas others have lost the requirement for epidermal growth factor for clonal growth. Aneuploidy and marker chromosomes have also been noted. However, none of these NiSO4-altered cell cultures are anchorage independent nor do they produce tumors upon injection into athymic nude mice.

Bronchi↗
PubMed1984

Multimethod determination of occupational exposure to polycyclic aromatic hydrocarbons in an aluminum plant.

Occupational exposure to polycyclic aromatic hydrocarbons (PAH) in an aluminum smelter has been characterised simultaneously by three different techniques. Air samples were collected by personal sampling and analysed by capillary gas chromatography. Urine samples of exposed workers and a control group, smokers and non-smokers, were collected after shift and analysed for PAH and PAH-metabolites by reversed metabolism and high performance liquid chromatography using fluorescence detection. Blood samples were collected from the same persons and the frequency of sister chromatid exchange (SCE) in the lymphocytes determined. The results showed that workers are exposed to very high concentrations of PAH. This high exposure is not reflected in significantly different values of excreted PAH metabolites or in SCE when comparing exposed to non-exposed workers. However, differences between smokers and non-smokers are easily identified both in exposed and non-exposed workers.

Adult↗
PubMed1984

Induction of squamous differentiation of normal human bronchial epithelial cells by small amounts of serum.

Recently we reported a low calcium (110 microM) serum-free medium (LHC-1) for clonal growth of normal human bronchial epithelial (NHBE) cells. NHBE cells within colonies are small (mean surface area = 1,250 mu2) rarely migratory, have few tonofilaments, and multiply with an average population doubling time of 28 h. We have also noted that adding small amounts of blood-derived serum to LHC-1 medium (as little as 2%) significantly decreased the clonal growth rate. We have now found that the growth inhibiting effect of serum is due to the induction of squamous (terminal) differentiation. Serum quickly increases the size of the cells (mean surface area = 4,900 mu2). In addition, the cells acquire numerous desmosomal junctions and an extensive network of keratin bundles. In contrast, human lung carcinoma cells multiply rapidly at clonal density in LHC-1 medium containing as much as 8% serum. Although high concentrations of calcium ions in the medium are known to induce squamous differentiation of epidermal keratinocytes in the absence of serum, high levels of Ca2+ (up to 1,000 microM) increased the number of desmosomal junctions, but did not significantly affect the clonal growth rate or size of the NHBE cells. However, high concentrations of calcium (above 450 microM) were found to potentiate serum differentiation-inducing activity. On the other hand, cholera toxin (10 ng/ml) inhibited the differentiation-inducing activity of serum. These results show that squamous differentiation of NHBE cells can be induced by serum and the potency of these serum factors can be modulated. In addition, the data show that lung carcinoma cells differ from their normal counterparts by not undergoing differentiation in the presence of serum.

Blood Physiological Phenomena↗
PubMed1983

Repair of premutagenic DNA lesions in human fetal tissues: evidence for low levels of O6-methylguanine-DNA methyltransferase and uracil-DNA glycosylase activity in some tissues.

The activities of the DNA repair enzymes O6-methylguanine-DNA methyltransferase and uracil-DNA glycosylase, and the replicative enzyme DNA polymerase alpha, were measured in extracts of human fetal tissues at 18-20 weeks of gestation. In general, O6-methylguanine-DNA methyltransferase activities in fetal tissues were in the same range as in the corresponding adult tissues, except for fetal liver which had approximately 5-fold lower activity. Uracil-DNA glycosylase was, surprisingly, approximately 4-fold lower in fetal tissues compared with adult tissues. Since a critical factor in carcinogenesis may be the rate of repair relative to DNA replication, the activities of O6-methylguanine-DNA methyltransferase and uracil-DNA glycosylase were compared with the DNA polymerase alpha activity in the same extract. When expressed in this way, O6-methylguanine-DNA methyltransferase activity was lowest in liver and brain and 2- to 14-fold higher in kidney, lung, colon, stomach, small intestine and pancreas. The ratio of uracil-DNA glycosylase to DNA polymerase alpha varied less between different organs. These findings indicate that several fetal organs may be more sensitive than adult organs to some alkylating agents that are known to occur in the environment. Furthermore, the lower capacity of DNA repair is not restricted to repair of alkylation damage, since the activity of uracil-DNA glycosylase is also lower than in adult tissues.

DNA Glycosylases↗
PubMed1982

Clonal growth of normal adult human bronchial epithelial cells in a serum-free medium.

Defined culture conditions for routine clonal growth of normal human adult bronchial epithelial cells have been developed. Serum and feeder cell requirements were abrogated by: (a) optimizing the calcium concentration in nutrient medium, MCDB 151; (b) supplementing with purified factors (epidermal growth factor, 5 ng/ml; insulin, 5 micrograms/ml; transferrin, 10 microgram/ml; hydrocortisone, phosphoethanolamine and ethanolamine, each at 5 x 10(-7) M; and trace elements); and (c) coating the surface of the culture dish with a mixture of fibronectin, collagen, and bovine serum albumin. Endothelial cell growth supplement (100 micrograms/ml) and retinoic acid (3 x 10(-10) M) further enchanced growth, whereas cholera toxin was nonmitogenic and serum supplementation (greater than 2%) markedly reduced the growth rate. Using the defined system, dissociated cultures of bronchial epithelial cells, obtained from more than 15 donors, have been subcultured at clonal densities with a colony forming efficiency of 3 to 4%. In addition, high density cultures have been subcultured more than five times with four to six population doublings per passage. The features of this system permit pathobiologic investigations of bronchial epithelial cells, e.g., aging, differentiation, and carcinogenesis using conditions that isolate the results from the influence of serum, feeder cells, and other undefined factors.

Adult↗
PubMed1982

Comparison of benzo(a)pyrene metabolism in bronchus, esophagus, colon, and duodenum from the same individual.

The metabolism of benzo(a)pyrene has been investigated in cultured normal human bronchus, colon, duodenum, and esophagus obtained from the same patient. The highest total metabolism was found in bronchus and duodenum, while the highest mean binding level was observed in the bronchus followed, in order, by the esophagus, duodenum, and transverse colon. A 30-fold interindividual variation in the binding level was found in each of the four organs studied, and a positive correlation between the binding levels in bronchus, colon, and duodenum was found. In human bronchus, a positive correlation was found between level of binding of benzo(a)pyrene to DNA and the amount of both benzo(a)pyrene 7,8-diol and the combined group of 3-hydroxybenzo(a)pyrene, benzo(a)pyrene 9,10-diol, and water-soluble metabolites. A significantly higher relative amount of benzo(a)pyrene tetrols and benzo(a)pyrene 9,10-diol was formed by human bronchus compared to the gastrointestinal tissues, while a higher level of benzo(a)pyrene phenols was formed by the latter. The relative distribution of benzo(a)pyrene-DNA adducts was similar in all four organs, the major DNA adduct being formed by trans-addition of anti-7,8-dihydroxy-9,10-epoxide-7,8,9,10-tetrahydrobenzo(a)pyrene to the 2-amino group at guanine. These results indicate that the metabolism of benzo(a)pyrene by at least four different organs is qualitatively similar but that quantitative differences exist.

Adolescent↗
PubMed1982

Quantitation of aflatoxin B1-modified DNA using monoclonal antibodies.

Five monoclonal antibodies were obtained after fusion of mouse P3 x 63 myeloma cells with spleen cells isolated from BALB/c mice that had been immunized with aflatoxin B1-adducted DNA complexes with methylated bovine serum albumin. Selected hybridomas were found to produce monoclonal antibodies specific for modified DNA containing both the 2,3-dihydro-2-(N7-guanyl)-3-hydroxyaflatoxin B1 and the putative 2,3-dihydro-2-(N5-formyl-2',5',6'-triamino-4'-oxo-N5-pyrimidyl)-3-hydroxyaflatoxin B1, suggesting that these DNA adducts share a common antigenic determinant. Enzyme immunoassay conditions using these monoclonal antibodies were optimized, and DNA isolated from the livers of rats given dosages of aflatoxin B1 ranging from 0.01 to 1.0 mg aflatoxin B1 per kg body weight was tested. A level of modification in DNA of 1 aflatoxin B1 residue per 1,355,000 nucleotides can be quantitatively measured. Monoclonal antibodies will be useful probes for studying the molecular interactions of aflatoxin B1 with DNA and the occurrence of aflatoxin B1:DNA adducts in tissues and cells of humans exposed to this environmental carcinogen.

Aflatoxin B1↗
PubMed1982

Studies of host factors in carcinogenesis using cultured human tissues and cells.

Recent progress in the development of conditions for culturing epithelial tissues and cells from adult humans has provided cancer researchers with an opportunity to investigate directly the various facets of carcinogenesis in human cells. Studies of activation and deactivation of several classes of chemical carcinogens have revealed that the metabolic pathways and the predominant adducts formed with DNA are generally similar in humans and experimental animals. Wide quantitative interindividual differences are found in humans and other outbred animal species. When the metabolic capabilities of specimens from different levels of biological organization are compared, the profile of benzo[a]pyrene metabolites is similar in cultured tissues and cells, but subcellular fractions, e.g., microsomes, produce a qualitatively and quantitatively aberrant pattern. To test the interactive effects of cell types in the metabolic activation of carcinogens and to assess further interindividual differences among people, human tissue- and cell-mediated mutagenesis assays have been developed. The fact that terminally differentiated cells such as pulmonary alveolar macrophages can activate benzo[a]pyrene and mediate an increase in frequencies of mutations and sister chromatid exchanges in cocultivated 'detector' cell populations, i.e., Chinese hamster V79 cells, suggests that non-target cells of chemical carcinogens may play an important role in the activation of environmental carcinogens. Malignant transformation of human epithelial and fibroblastic cells in vitro has been accomplished by several research groups. Asbestos, a cocarcinogenic agent in bronchogenic carcinogenesis, has been found to induce polyploid epithelial lesions with atypical cells in human bronchial explants. Carcinogenesis studies using cultured human tissues and cells are providing new insights into the mechanisms of carcinogenesis and are useful in identifying host factors that influence individual risk to environmental carcinogens.

Biotransformation↗