1,720,969 research outputs found
Coal tar therapy does not influence in vitro benzo[a]pyrene metabolism and DNA adduct formation in peripheral blood lymphocytes of psoriatic patients
No full textHuman lymphocytes (HL) from healthy subjects and psoriatic patients were treated in vitro for 24 h with 4 microM [3H]benzo[a]pyrene (B[a]P) and 2 microM (-)-B[a]P-7,8-dihydrodiol in order to verify if the coal tar (CT) used in the therapy of psoriasis, which is characterized by a high content of polycyclic aromatic hydrocarbons (PAH), influences the formation of B[a]P-DNA adducts and the metabolism of B[a]P. Significant amounts of syn-BPDE-dGuo adducts were detected in all the examined HL samples, but no significant difference in the amounts of total BPDE-DNA adducts or of specific anti- and syn-BPDE-dGuo adducts was observed between healthy subjects and psoriatic patients, or between psoriatic patients before and after CT treatment. Moreover, the CT treatment of psoriatic patients did not influence the enantiomeric composition of B[a]P-7,8-dihydrodiols present in the HL culture medium, among which the (-)-7R,8R form was found to predominate (greater than 98%) in all the HL samples. The existence in HL of a specific metabolic pathway of B[a]P leading to the formation of (-)-syn-BPDE and the corresponding tetrols, through the epoxidation of the (-)-7R,8R enantiomer of B[a]P-7,8-dihydrodiol, was confirmed by determining the tetrols derived from the syn- and anti-stereoisomers of BPDE, released in HL culture medium after treatment for 24 h with 2 microM (-)-B[a]P-7,8-dihydrodiol. Although B[a]P-7,10/8,9 and B[a]P-7/8,9,10 tetrols, derived from (+)-anti-BPDE, were the predominant isomers, significant amounts of B[a]P-7,9/8,10 and B[a]P-7,9,10/8 tetrols, derived from the hydrolysis of (-)-syn-BPDE, were also detected. The mean ratio of anti/syn tetrols in healthy subjects was significantly lower than in psoriatic patients, but no difference in that ratio was found in psoriatic patients before and after CT treatment
Mammalian cell transformation induced by chromium(VI) compounds in the presence of nitrilotriacetic acid.
No full textWe used a soft agar assay on cultured Syrian hamster fibroblasts to determine the ability of nitrilotriacetic acid (NTA) and Cr(VI) compounds to induce malignant cell transformation. Induction of extended anchorage-independent growth was detected in BHK 21/c13 cells by scoring colonies of transformed cells visible to the naked eye 20-25 d after plating in growth medium containing agar. Survival was determined by plating cells in liquid medium without agar and by counting the number of macroscopic colonies after 7-10 d. Mitomycin C and 4-nitroquinoline 1-oxide were used as reference direct transforming agents, with clearly positive results. In our hands no increase of the spontaneous transformation rate of BHK cells was induced by NTA concentrations ranging from 2 X 10(-3) to 10(-2) M, although the survival index was significantly reduced above 4 X 10(-3) M NTA. Two Cr(VI) compounds, K2Cr2O7, which is highly soluble in water, and CaCrO4, which is partially soluble, were tested in the soft agar assay either in the absence or in the presence of NTA. When used alone, both compounds behaved as positive transforming agents. NTA increased 4 or 10 times the cytotoxicity and the transforming activity of CaCrO4 and K2Cr2O7, respectively. As the amounts of soluble Cr(VI) detectable in the K2Cr2O7 and CaCrO4 solutions were not increased in the presence of NTA, a synergistic interaction between NTA and soluble Cr(VI) is inferred
Human peripheral blood lymphocytes as a cell model to evaluate the genotoxic effect of coal tar treatment
No full textPeripheral blood lymphocytes (PBL) from psoriatic patients therapeutically exposed to polycyclic aromatic hydrocarbons (PAH) during coal tar (CT) treatment were used to evaluate the in vivo formation of benzo[a]pyrene diol epoxide(BaPDE)-DNA adducts by an ELISA technique and by the 32P-postlabeling method. Moreover, we controlled if the pretreatment with CT influences the formation of BaP-DNA adducts and the BaP metabolism in the PBL obtained from psoriatic patients, treated in vitro with BaP. Our data did not show any significant influence of the CT treatment on the levels of PAH-DNA adducts. Moreover, the use of PBL from psoriatic patients, treated in vitro with BaP, did not allow to detect significant modifications of the metabolic activation of BaP and of the ability of its metabolites to bind to DNA, before and after CT treatment. Thus, PBL do not seem to represent an useful cell model to evaluate the possible genotoxic effect of the exposure through the skin of psoriatic patients to the PAH contained in CT
Interactions of nitrilotriacetic acid (NTA) with Cr(VI) compounds in the induction of gene mutations in cultured mammalian cells
No full textDNA damage and repair induced in vitro by nitrilotriacetic acid (NTA) in human lymphocytes
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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