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C C Harris

Publications and source records attributed to C C Harris.

At least 361 records · Page 20Linked to original sources
PubMed1982

Differences in metabolism of chemical carcinogens in cultured human epithelial tissues and cells.

The metabolism of chemical carcinogens has been studied in cultured human bronchus, colon, duodenum, pancreatic duct, and esophagus. Metabolite patterns and carcinogen-DNA adducts are generally qualitatively similar among animal species, individuals within a species, and tissues within an individual. However, wide quantitative differences are observed between individuals in outbred animal species, including humans. These interindividual differences in amounts of carcinogen-DNA adducts and in activities of enzymes that are important in the metabolism of chemical carcinogens are similar in magnitude (10-to 150-fold) to those observed in pharmacogenetic studies of drug metabolism. The role of these differences as risk factors in human cancer is being investigated.

Aryl Hydrocarbon Hydroxylases↗
PubMed1982

DNA repair in human bronchial epithelial cells.

The purpose of this investigation was to compare the response of human cell types (bronchial epithelial cells and fibroblasts and skin fibroblasts) to various DNA damaging agents. Repair of DNA single strand breaks (SSB) induced by 5 krads of X-ray was similar for all cell types; approximately 90% of the DNA SSB were rejoined within one hour. During excision repair of DNA damage from u.v.-radiation, the frequencies of DNA SSB as estimated by the alkaline elution technique, were similar in all cell types. Repair replication as measured by BND cellulose chromatography was also similar in epithelial and fibroblastic cells after u.v.-irradiation. Similar levels of SSB were also observed in epithelial and fibroblastic cells after exposure to chemical carcinogens: 7,12-dimethylbenz[a]anthracene; benzo[a]pyrene diol epoxide (BPDE); or N-methyl-N-nitro-N-nitrosoguanidine. Significant repair replication of BPDE-induced DNA damage was detected in both bronchial epithelial and fibroblastic cells, although the level in fibroblasts was approximately 40% of that in epithelial cells. The pulmonary carcinogen asbestos did not damage DNA. DNA-protein crosslinks induced by formaldehyde were rapidly removed in bronchial cells. Further, epithelial and fibroblastic cells, which were incubated with formaldehyde and the polymerase inhibitor combination of cytosine arabinoside and hydroxyurea, accumulated DNA SSB at approximately equal frequencies. These results should provide a useful background for further investigations of the response of human bronchial cells to various DNA damaging agents.

Asbestos↗
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↗
PubMed1981

Cultured human bronchial epithelial cells: blood group antigens, keratin, collagens, and fibronectin.

Immunofluorescence and immunoperoxidase methods were used to identify constituents and products of cultured human bronchial epithelial cells and fibroblasts. Epithelial cells, but not fibroblasts, from patients with blood Types A or B reacted to the respective antisera to either the A or B blood group antigens. However, neither the epithelial cells nor the fibroblasts from patients with blood type O[H] reacted with the anti-H antisera. Epithelial cells in primary culture reacted with antibody to prekeratin proteins from human stratum corneum and fibroblasts did not react. Moreover, keratin filaments were assembled in vitro from proteins isolated from the epithelial cells. These immunological and biochemical data support previous morphological observations that human bronchial epithelial cells in primary culture shift progressively from a mucociliary epithelium to a keratinizing epithelium. Epithelial cells and fibroblasts could also be identified by their reactivity to anti-collagen antibodies. Fibroblasts reacted strongly with antibodies to Types I and III collagens and epithelial cells did not. On the other hand, epithelial cells reacted weakly with antibodies to Type IV collagen and fibroblasts were completely negative. Both epithelial cells and fibroblasts reacted with antibody to fibronectin; however, the distribution of fibronectin differed in the two cell types. In epithelial cells, fibronectin was restricted to the cell surface, whereas in fibroblasts it was found on the cell surface and in the extracellular matrix where fibrils of fibronectin were both cell associated and deposited on the surface of the dish where the fibroblasts had migrated.

ABO Blood-Group System↗
PubMed1981

Explant culture of rat esophagus in a chemically defined medium.

Esophagus from adult male CDF rats was cultured for a period of 28 d in CMRL-1066 medium supplemented with pyruvic acid, HEPES buffer, beta-retinyl acetate, and antibiotics. Morphological, radioautographic, and biochemical studies indicated that the survival of the tissue in serum-free medium was equivalent to that in medium containing 5% heat-inactivated fetal bovine serum. There was a relatively constant uptake of [3H]thymidine into DNA and [3H]leucine into protein of the esophageal explants during the incubation. Only the basal cells of the epithelium incorporated [3H]thymidine into their nuclei. The normal morphology of the tissue was preserved when the explants were maintained at both 37 and 30 degrees C, and in either 50 or 20 % 02. Ninety-five percent O2 was highly toxic to the cells of the explants. This culture system should be suitable for a variety of investigations in esophageal cell differentiation and carcinogenesis.

Animals↗
PubMed1981

DNA-protein cross-linking by chromium salts.

DNA-protein cross-links were detected in several types of mammalian cells in culture when they were exposed to chromate salts. The cell types included human bronchial epithelial cells--the apparent cell type of origin of the malignancies reported in chromate workers. The level of cross-linking was proportional to the concentration of chromate used. These cross-links appeared to be persistent since no removal was seen after 12 h of repair incubation. A low level of DNA single strand breaks (SSB) were also induced after exposure of the cells to chromate but were rejoined after 4 h of repair incubation. The active form of chromium appears to be the trivalent since chromic but not chromate salts induced DNA-protein cross-links in isolated nuclei. Chromic salts also produced cross-linking between DNA and protein in solution while the hexavalent form was inactive. These data imply that chromate crosses the cell membrane, is reduced to the trivalent form and induces stable linkages of DNA to protein.

Animals↗
PubMed1981

Monoclonal antibody to aflatoxin B1-modified DNA detected by enzyme immunoassay.

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 complexed with methylated bovine serum albumin. Selected hybridomas were found to produce monoclonal antibodies specific for aflatoxin B1-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. The monoclonal antibody was not reactive towards the free aflatoxin B1-guanine adducts in solution, seven other aflatoxin derivatives, or benzo[a]pyrene-adducted DNA. A noncompetitive ultrasensitive enzyme radioimmunoassay could measure 15 fmol of aflatoxin B1-DNA adducts in 10 ng of DNA and was at least 100-fold more sensitive than the standard enzyme-linked immunosorbent assay. Competitive enzyme-linked immunosorbent assay with these monoclonal antibodies reliably quantitated aflatoxin B1 adducted in vivo to rat liver DNA at adduct levels of one aflatoxin B1 residue per 250,000 nucleotides. The competitive ultrasensitive enzyme radioimmunoassay was determined to be at least 6-fold more sensitive than the competitive enzyme-linked immunosorbent assay in analysis of aflatoxin B1-adducted DNA. Therefore, enzyme immunoassay using monoclonal antibodies will be useful analytical tools for studying both the molecular interactions of aflatoxin B1 with DNA and the occurrence of aflatoxin B1-DNA adducts in biological specimens from people exposed to this environmental carcinogen.

Aflatoxin B1↗
PubMed1981

In vivo tumor localization using tumor-specific monkey xenoantibody, alloantibody, and murine monoclonal xenoantibody.

Specific in vivo localization of antibodies reactive with human melanoma cell membrane tumor associated antigens (TAA) has been attempted using congenitally athymic nude mice bearing subcutaneous human melanoma tumor xenografts as the experimental model. IgG fractions were prepared from each of several immune and control sera. Antimelanoma antibody sources included human alloantibody obtained from melanoma patients immunized against allogeneic melanoma cells, a monkey antiserum raised by immunization against a single human melanoma cell line, and a murine monoclonal antimelanoma antibody-secreting hybridoma cell line. Localization of these radiolabeled antibodies and of control IgG preparations to tumor tissue was determined by whole body scintigraphy and by differential tissue counting. Compared with the different control IgG preparations, each of the antimelanoma IgG preparations exhibited significant specific accumulation within the melanoma tissue. However, variation existed in the ability of each antimelanoma IgG to tumor preparation to localize despite attempts to control model parameters such as tumor source, in vivo passage number and mass. This variation appears to reflect basic biologic differences between tumors in different animals and possibly differences in the antigen-binding capacities of each IgG preparation following radioiodination. This technique for tumor localization is very promising and has obvious potential for clinical application.

Animals↗
PubMed1981

Acquisition planning for nuclear medicine imaging equipment.

The acquisition of imaging equipment is sometimes accomplished with less than optimal planning which leads less than satisfactory results. The purpose of this article is to outline a plan for acquisition designed to reduce some of the problems.

Decision Making↗
PubMed1981

Lymphoscintigraphy in malignant melanoma: 99mTc antimony sulfur colloid.

Lymphoscintigrams were performed using technetium-99m antimony sulfur colloid in 21 patients with cutaneous malignant melanoma. Scintigraphic results were concordant with clinical prediction of lymph drainage in six of 11 patients with trunk melanoma, in five of seven patients with extremity lesions, and in none of three patients with scalp melanoma. Thirteen patients showed activity in more than one regional node group. Eleven patients had focal activity in areas other than regional node groups (i.e., in-transit or central lymph nodes). Lymphadenectomy was performed in 19 patients. In each case, the regional lymph node area chosen for resection was positive scintigraphically. The presence of 99mTc activity in excised lymph nodes was documented by scintillation counting and autoradiography. Metastatic disease was found in the resected nodes of 12 patients. Lymphoscintigraphy may be useful in planning lymphadenectomy in some patients with cutaneous melanoma.

Adult↗
PubMed1981

Long-term survival of normal adult human tissues as xenografts in congenitally athymic nude mice.

Bronchi, pancreatic ducts, and colons from adult human were maintained as xenografts in congenitally athymic nude N:NIH(S) mice for 715, 145, and 89 days, respectively. After an ischemic crisis and revascularization of the human tissue, the epithelium regenerated to a normal differentiated morphology. The long-term survival of normal adult human epithelial tissues as xenografts provides model systems for the study of the interactions of chemical and/or physical carcinogens with human tissues.

Animals↗
PubMed1981

Clonal growth of epithelial cells from normal adult human bronchus.

Normal primary epithelial cell cultures devoid of fibroblastic cells have been developed from tissue explants of adult human bronchi. Conditions for clonal growth of secondary cultures of bronchial epithelial cells were optimized by coculturing the human cells with mitomycin C growth-arrested Swiss 3T3 mouse feeder cells, lowering the calcium concentration of medium M199, and supplementing it with hydrocortisone, insulin, cholera toxin, epidermal growth factor, and 1.25% fetal bovine serum. The epithelial cells grew for an average of 35 population doublings and had the normal human karyotype, expressed keratin and blood group antigen epithelial cell markers, metabolized benzo(a)pyrene, and were capable of differentiating into both ciliated and squamous cells. This culture system makes it potentially possible to investigate various aspects of differentiation and carcinogenesis in human bronchial epithelial cells.

Animals↗
PubMed1981

Measurement of benzo(a)pyrene-DNA adducts by enzyme immunoassays and radioimmunoassay.

Ultrasensitive enzymatic radioimmunoassay (USERIA) was compared to radioimmunoassay and enzyme-linked immunosorbent assay in determining the amount of benzo(a)pyrene [B(a)P] metabolite covalently bound to guanine in DNA. In the USERIA approach, DNA either with or without B(a)P metabolite modification was adsorbed on the wells of microtiter plates, and rabbit antiserum to B(a)P metabolite-modified DNA [B(a)P-DNA] was then added. Antibodies reacted specifically with the B(a)P-DNA attached to the surface of the plate. After reaction between goat anti-rabbit IgG conjugated to alkaline phosphatase and rabbit IgG bound to the solid phase, this specific antigen-antibody reaction was enzymatically amplified by alkaline phosphatase conversion of [3H]adenosine 5'-monophosphate to [3H]adenosine. Following chromatographic separation from [3H]adenosine5'-monophosphate, [3H]adenosine was measured by liquid scintillation counting. The amount of [3H]-adenosine formed was linearly related to the amount of B(a)P-DNA in 10 ng DNA attached to the solid phase. As little as 3 fmol of bound B(a)P metabolite can be detected by noncompetitive USERIA, while 10 fmol of the adducts in 25 microgram DNA [1 B(a)P-DNA adduct per 7 X 10(6) nucleotides] can be measured by the competitive USERIA approach. Under our standard competitive procedure with 1 microgram DNA in the antigen-antibody reaction mixture, USERIA is approximately 500-fold more sensitive than radioimmunoassay and 5-fold more sensitive than enzyme-linked immunosorbent assay for the detection of B(a)P-DNA adducts. These highly sensitive assays should be extremely useful for studies in DNA damage and repair by B(a)P metabolites as well as in studies on environmental exposure to this ubiquitous carcinogen.

Animals↗