Importance of regular testing of private drinking water systems in North Carolina.

North Carolina state laws require that water from newly constructed private wells be tested for chemical and microbiologic contamination, but existing wells are not routinely tested. This commentary highlights the importance of regular testing of all private sources of drinking water.

Relationship of Fuchs endothelial corneal dystrophy severity to central corneal thickness.

Objective: To define the relationship between Fuchs endothelial corneal dystrophy (FECD) severity and central corneal thickness (CCT).

Methods: We examined 1610 eyes from a subset of index cases, family members, and unrelated control subjects with normal corneas from the FECD Genetics Multi-Center Study. To estimate the association between FECD severity grade (7-point severity scale based on guttae confluence) and CCT measured by ultrasonographic pachymetry, a multivariable model was used that adjusted for eye, age, race, sex, history of glaucoma or ocular hypertension, diabetes mellitus, contact lens wear, intraocular pressure, and familial relationship to the index case.

Arsenic in North Carolina: public health implications.

Arsenic is a known human carcinogen and relevant environmental contaminant in drinking water systems. We set out to comprehensively examine statewide arsenic trends and identify areas of public health concern. Specifically, arsenic trends in North Carolina private wells were evaluated over an eleven-year period using the North Carolina Department of Health and Human Services database for private domestic well waters.

Generalized elastophagocytic granuloma.

The case of an eighty-three-year-old woman with the sudden onset of a generalized pruritic eruption is reported. The skin lesions resembled disseminated subacute lupus erythematosus on clinical examination, but actinic granuloma or annular elastolytic giant cell granuloma was seen in biopsy specimens of the lesions. Our case was differentiated from generalized granuloma annulare by the distinct zoning of elastolysis and the distribution of giant cells.

Human cytochrome P450IIA3: cDNA sequence, role of the enzyme in the metabolic activation of promutagens, comparison to nitrosamine activation by human cytochrome P450IIE1.

We report that, in a human cell line, human cytochrome P450IIA3 is capable of metabolizing aflatoxin B1, benzo[a]-pyrene, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) to cytotoxic and mutagenic species. Cytochrome P450IIA3-mediated activation of NDMA and NDEA was compared with human cytochrome P450IIE1-mediated activation in the same cell system. P450IIE1 was more effective at activating NDMA than P450IIA3, while P450IIA3 was more effective at activating NDEA than P450IIE1.

Comparative metabolism and genotoxicity of the structurally similar nitrophenylenediamine dyes, HC Blue 1 and HC Blue 2, in mouse hepatocytes.

Previous studies indicated that HC Blue 1 induced heptocellular carcinomas in B6C3F1 mice whereas the structurally similar nitroaromatic amine HC Blue 2 did not. In an attempt to elucidate the biochemical mechanisms responsible for their different carcinogenic potencies, comparative metabolism and genetic toxicity studies were undertaken. Eighteen-hour urinary recovery of administered radioactivity was equivalent for both compounds following oral gavage (100 mg/kg) in female B6C3F1 mice.

Transfection of cytochrome P450 cDNAs into mammalian cells used in mutation and transformation assays.

The present work demonstrates that cDNAs coding for cytochrome P450 enzymes can be transfected into mammalian cells and expressed. In the present studies, two different cell systems were used for transfection: 10T1/2 cells which can be used to study initiation and promotion (Diamond, 1984) and AHH-1 cells which can be used to study mutation and clastogenesis (Crespi and Thilly, 1984, Crespi and Penman, 1989). Thus, a diversity of endpoints can be studied in cells which have increased metabolic capability.

Development of a human cell line by selection and drug-metabolizing gene transfection with increased capacity to activate promutagens.

We have isolated a human lymphoblastoid cell line with higher levels of native cytochrome P450IA1 activity and by DNA transfection introduced human cDNAs for a putative cytochrome P450IIA2 and epoxide hydrolase (E.C. 3.

Human and rat kidney cell metabolism of 2-acetylaminofluorene and benzo(a)pyrene.

The metabolism and mutagenic activation of the model carcinogens benzo(a)pyrene [B(a)P] and 2-acetylaminofluorene (AAF) by human and rat kidney cells were measured. A slicing technique followed by enzyme digestion was utilized to obtain the kidney cells. Although levels of total metabolism of B(a)P by rat and human kidney cells were similar, analysis of specific metabolites of B(a)P indicated that species differences existed.

Transfection of a human cytochrome P-450 gene into the human lymphoblastoid cell line, AHH-1, and use of the recombinant cell line in gene mutation assays.

We have demonstrated that the human cytochrome P1-450 gene can be transfected into the AHH-1 human lymphoblastoid cell line using the pHEBo vector and hygromycin selection. The transfected gene was expressed when regulatory sequences derived from the herpes simplex virus thymidine kinase gene were incorporated in appropriate orientations. Gene expression was monitored at the enzyme level using assays for 7-ethoxyresorufin deethylase, 7-ethoxycoumarin deethylase and benzo[a]pyrene hydroxylase activities.

Transfection of a rat cytochrome P450b cDNA into C3H10T1/2CL8 mouse embryo fibroblasts.

A cDNA clone of a rat cytochrome P450b gene was used to construct an expression vector driven by an SV40 promoter and containing a G418-resistance selectable marker. This bifunctional plasmid (pJRSL100) was transfected into the C3H 10T1/2CL8 mouse embryo fibroblast cell line. G418-resistant clones were selected and tested for enhanced sensitivity to the carcinogen 2-acetylaminofluorene (2-AAF), a compound that does not normally induce cytotoxicity or morphological transformation in these cells.

Human hepatocyte and kidney cell metabolism of 2-acetylaminofluorene and comparison to the respective rat cells.

The metabolism and mutagenic activation of 2-acetylaminofluorene by human and rat hepatocytes and kidney cells were measured. High performance liquid chromatography was used to separate the 2-acetylaminofluorene metabolites, and a cell-mediated Salmonella typhimurium mutagenesis assay was used to detect mutagenic intermediates. Rat and human differences were observed with cells from both organs and levels of metabolism and mutagenesis were higher in human cells.

Comparison of human and rat hepatocyte metabolism and mutagenic activation of 2-acetylaminofluorene.

A method has been developed to assess the metabolism and mutagenic activation of carcinogens using human and rodent hepatocytes in vitro. A slicing technique which was especially useful for nonperfusable biopsy and resected surgical human liver tissue was used to prepare the hepatocytes. Metabolites of the model carcinogen 2-acetylaminofluorene (AAF) produced by human and rat hepatocytes were similar and consisted primarily of 2-aminofluorene with ring hydroxylated products at the 1-, 3-, 5/9-, 7-, and 8-positions produced in addition to N-hydroxy-AAF.

Species variation in bladder cell and liver cell activation of acetylaminofluorene.

The metabolism and mutagenicity of 2-acetylaminofluorene were measured using freshly prepared intact bladder and liver cells from the cow, dog and rat. High pressure liquid chromatography was used to separate 2-acetylaminofluorene metabolites, and Salmonella typhimurium, strain TA98, was used to detect mutagenic intermediates. Species differences as well as animal-to-animal variation within a species were observed.

Morphological transforming activity and metabolism of cyclopenta-fused isomers of benz[a]anthracene in mammalian cells.

4 isomeric cyclopenta-derivatives of benz[e]anthracene (benz[a]aceanthrylene, benz[j]aceanthrylene, benz[l]aceanthrylene, and benz[k]acephenanthrylene) were examined for their ability to morphologically transform C3H10T1/2CL8 mouse-embryo fibroblasts. All of these polycyclic aromatic hydrocarbons studied except benz[k]acephenanthrylene transformed C3H10T1/2CL8 cells to both type II and type III foci in a concentration-dependent fashion. Benz[j]aceanthrylene was the most active, equivalent in activity to benzo[a]pyrene on a molar basis, in producing dishes of cells with transformed foci (94% at 1.

Metabolism of benzo(a)pyrene in monolayer cultures of human bronchial epithelial cells from a series of donors.

Benzo(a)pyrene [B(a)P] metabolism was measured in monolayer cultures of human bronchial epithelial cells derived from 18 specimens of explanted tissue. Bronchial epithelial cells converted B(a)P to dihydrodiols, phenols, quinone derivatives, and polyhydroxylated forms. Sulfate and glucuronide conjugates of B(a)P metabolites were also detected.

Quantitative analysis of the metabolism of benzo(a)pyrene by transformable C3H10T1/2CL8 mouse embryo fibroblasts.

The metabolism of benzo(a)pyrene [B(a)P] to organic soluble and water soluble metabolites by transformable C3H10T1/2CL8 mouse embryo fibroblasts was studied as a function of time, B(a)P concentration, and cell density. The total formation of organic-soluble and water-soluble metabolites increased with incubation time from 4 to 48 h and with B(a)P concentration from 4 to 40 microM. As cell density increased, the metabolic rate decreased for organic-soluble and water-soluble products between 6,300 and 54,000 cells/cm2 probably due to decreases in B(a)P concentrations to values below saturation.

Reanalysis and clarification of the structures of alpha-naphthoflavone dihydrodiols formed by uninduced and induced rat liver microsomes from Charles River CD and Sprague-Dawley rats.

The structures of alpha-naphthoflavone (ANF) dihydrodiols formed by uninduced and induced rat liver microsomes are identified by conversion of the metabolically formed ANF-dihydrodiols to the corresponding phenols. Comparison of these phenols with synthetic standards provides an unambiguous method for structural identification. The results of these studies are that hepatic microsomes from uninduced or phenobarbital, Aroclor-1254, 3-methylcholanthrene, or 5,6-benzoflavone induced Sprague-Dawley or Charles River CD rats each produce a major and a minor ANF-dihydrodiol identified as ANF-7,8-dihydrodiol and ANF-5,6-dihydrodiol, respectively.