[' ', 'MATERIALS', 'AND', 'METHODS', 'Cheinicals:', 'BP', 'and', 'phenol', '(>', '9993', 'pure)', 'were', 'purchased', 'from', 'Aldrich', 'Chernical', 'Co,', '(Milwaukee,', 'WI),', 'Standard', 'therapeutic.', 'CCT', '(USP)', 'was', 'used.', 'All', 'other', 'chemicals', 'used', 'were', 'of', 'the', 'highest', 'purity', 'commercially', 'available.', 'Animals', 'and', 'Treatment:', 'Eight', 'week-old', 'male', 'Sencar', 'mice', 'obtained', 'from', 'the', 'NCI-Frederick', ' ', 'Cancer', 'Research', 'Facility', '(Bethesda,', 'MD)', 'were', 'used', 'in', 'this', 'study,', 'The', 'mice', 'were', 'shaved', 'with', 'electric', 'clippers', 'and', 'Nair', 'depilatory', 'was', 'applied', '1', 'day', 'prior', 'to', 'beginning', 'the', 'experiment,', 'Only', 'those', 'mice', 'not', 'in', 'the', 'hair', 'growth', 'cycle', 'were', 'selected', 'for', 'studies.', 'Eighty', 'mice', 'were', 'divided', 'into', 'cight', 'groups', 'of', '10', 'animals', 'each', 'and', 'received', 'the', 'following', 'topical', 'treatments:', 'Group', 'I}', '100', 'pl', 'of', 'acetone', '(control),', 'Group', 'II)', '20', 'ps', 'of', 'BP', 'in', '100', 'pl', 'acetone,', 'Group', 'Ill,', 'IV,', 'and', 'V)', 'received', '100,', '200,', 'and', '500', 'pl', 'of', 'CCT', 'respectively.', 'Group', 'VI,', 'VI,', 'and', 'VHI)', 'received', '20', 'ps', 'of', 'BP', 'in', 'combination', 'with', '100,', '200,', 'and', '500', 'p', 'of', 'CCT,', 'respectively,', 'Seventy-two', 'hours', 'after', 'the', 'initial', 'treatment,', 'all', 'animals', 'received', 'the', 'same', 'dose', 'again', 'and', 'were', 'killed', '24', 'hrs', 'later.', 'This', 'treatment', 'protocol', 'for', 'BP', 'has', 'been', 'shown', 'to', 'produce', 'maximal', 'adducts', 'in', 'mouse', 'epidermis', '(15).', 'Extraction', 'and', 'Estimation', 'of', 'DNA:', 'DNA', 'was', 'extracted', 'from', 'epidermal', 'and', 'lung', 'homogenates', 'essentially', 'as', 'described', 'by', 'Kates', 'and', 'Beeson', '(11)', 'with', 'an', 'additional', 'incubation', 'step', 'using', 'protease', 'K', '(9.5', 'mg/ml),', 'A', 'second', 'extraction', 'was', 'performed', 'using', "Kirby's", 'phenol', '(6)', 'before', 'precipitation', 'with', 'cold', '100%', 'ethanol.', 'The', 'DNA', 'was', 'digested', 'with', 'ribonuclease', 'A', '(1000', 'units/ml),', 'washed', '3', 'times', 'with', 'acetone,', 'and', 'dried', 'under', 'a', 'stream', 'of', 'nitrogen.', 'The', 'extracted', 'DNA', 'was', 'then', 'dissolved', 'in', '5.0', 'ml', 'of', '0.1', 'M', 'sodium', 'chloride', '(pH', '7.0)', 'and', 'estimated', 'by', 'measuring', 'its', 'ebsorpilon', 'at', '260', 'nm,', 'The', 'purity', 'of', 'DNA', 'was', 'assessed', 'by', 'the', 'cbsorbance', 'ratio', '260/280', 'Y', '1,98', 'and', '260/230', '>', '2.21', '(2).', 'ELISA', 'for', 'BPDE-l-dG_', 'Adducts:', 'BPDE-I-dG', 'antibedy', 'reactivity', 'was', 'quantitated', 'by', 'a', 'competitive', 'ELISA', '(17,21)', 'using', 'a', 'highly', 'specific', 'monoclonal', 'entibody', '(5D11)', 'which', 'recognizes', 'BPDE-L', 'modified', 'DNA.', 'in', 'addition', 'there', 'is', 'cross', 'reactivity', 'with', 'DNA', 'modified', ' ', '50161973']