Carcinogenic Aromatic Hydrocarbons Research Articles

Kinetic Regularities Research of the Convective Concentration Process of a Hexane-Paraffinic Composition for the Food Paraffin Production

Film structures, used for the production of biodegradable packaging materials, are hydrophilic in nature. Their paraffinization reduced the influence of external factors, primarily moisture, for them, i.e. applying a thin layer of molten food paraffin to the film surface for subsequent protection of packaged food products from moisture and sunlight. While producing the moisture-repellent compositions, a man pays much attention to the quality of the final food paraffin. One of its important safety indicators is the absence of carcinogenic aromatic hydrocarbons in it. The kinetic regularities study of the convective concentration processes of a technical paraffin solution in n-hexane is necessary to analyze their mechanism and speed, depending on the operating parameters, making possible to determine the rational duration of these procedures and the specific yield of the resulting product. To rationalize the convective concentration of a hexane solution, it is necessary to select such operating parameters enabling not only to remove hexane with toxic components dissolved in it from the study object in a relatively simple apparatus, but also to significantly reduce the time for this process. The study aim was to determine the rational modes of hexane-paraffin mixture concentration, as an object for the food paraffin production with convective energy supply. The concentration curve nature, although it is typical for the interacting materials, in particular n-hexane and paraffin, has a certain specificity, determined by the physicochemical parameters of the research object, which is a true solution included various toxic substances. The specific features of the study object are to be reflected not only on the solution concentration mechanism, but also on the temperature fields evolution in it and, as a result, determine the original approaches to modeling the process of removing the solvent together with toxic substances, particularly, benz-α-pyrene.

Model studies on benzene formation from benzaldehyde

The carcinogenic aromatic hydrocarbon benzene has recently been detected in drinks with added cherry flavour, and it was suggested that benzene could be formed from benzaldehyde used as flavouring. To get a deeper insight into parameters favouring benzene formation, the influence of light, pH, oxygen, temperature as well as presence of transition metal ions was studied in model solutions of benzaldehyde. It was found that in particular irradiation with light increased benzene formation. However, this was not observed in a cherry juice most probably due to absorption of light by the red colour. Therefore, the benzene detected in commercial cherry juices may have been added as contaminant of the benzaldehyde used in the flavouring. The assumption was confirmed by the analysis of commercial flavourings. Thus, to avoid benzene formation in flavourings, amber glass vials must be used during production, storage and sale.

Finding the Relationship Between the Biological Dagradtion Rate Constants and Some of the Calculated Physical Properties of a Number of Carcinogenic poly Aromatic Hydrocarbons

This study involves the theoretical calculation of binding energy (the free energy ΔG°) of eleven of polycyclic aromatic hydrocarbons (PAHs) compounds with catechol 1,2-dioxygenase enzyme from the gram-positive Rhodococcus opacus (3HGI) enzyme that is used for degrading these types of compounds and also identifies the values of binding energy that compactable with constant values of biological degradation rate. It is noted that binding energy inversely proportional with rate constants and binding energy (R=0.951), as the binding energy with enzyme are increased, the degradation rate are decreased.The study observes that binding energy values were ranging between ([-5.051] - [-7.12] Kcal/mol) whereas values of root mean squared deviation (RMSD) were ranging between (1.12-1.71A°) by which accurate results have been confirmed depending on previous studies. The study also determines the amino acids that surround the compounds which are usually blinded by the hydrogen bond or hydrophobic interactions types π-π.Finally, the study obtains a three – dimensional shape of compound's binding with enzyme of its more stable shape. Also obtains the shapes of distribution of the electronic cloud on the compound and amino acids that are surrounding them in which getting locations around the studied compound's molecule depending on their features of an amino acid (acidity – basic – hydrophobic). MOE (Molecular Operating Environment) is used for this step of calculation.

Abstract 498: Attenuation of polycyclic aromatic hydrocarbon (PAH)-mediated pulmonary carcinogenesis in mice by omega-3-fatty acids

Abstract 3-Methylcholanthrene (MC) and benzo[a]pyrene (BP) are potent polycyclic aromatic hydrocarbons (PAHs) carcinogens. PAHs are present in cigarette smoke, diesel exhausts, and charcoal broiled meats, etc. Cytochrome P450 (CYP) 1A/1B1 enzymes play key roles in the activation of PAHs to carcinogenic metabolites, which initiate carcinogenesis by binding covalently to DNA, and the adducts, if not repaired, could lead to tumorigenesis. In this study we tested the hypothesis that pre-treatment of mice with omega-3-fatty acids, i.e. [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) will lead to attenuation of PAH-mediated pulmonary DNA adduct formation and pulmonary tumorigenesis. Twelve week old male and female A/J mice received EPA (60 mg/kg) and DHA (40 mg/kg) from day 1 to day 24. Control mice were treated with vehicle corn oil. On day 3, mice were treated with BP (40 µmol/kg) or 3-methylcholanthrene (MC, 40 µmol/kg) by i.p. In the short-term experiment (DNA adduct studies), 3-5 mice from each group were terminated at day 10 (7 days after BP or MC treatment). EPA/DHA significantly suppressed formation of BP-DNA and MC-DNA adducts in lung and liver of both male and female mice. In the long-term experiment (tumor studies), 8 mice for each group continued to receive EPA/DHA twice per week till end of experiment (16 weeks). Pulmonary tumor incidence and multiplicity was significantly suppressed in mice given EPA+DHA, compared to those given the PAHs, BP or MC alone. These studies suggest that the omega 3-fatty acids could be developed as novel candidates for the prevention of PAH-mediated lung cancers in humans. Citation Format: Bhagavatula Moorthy, Weiwu Jiang, Lihua Wang, Sudha R. Kondraganti, Guodong Zhou. Attenuation of polycyclic aromatic hydrocarbon (PAH)-mediated pulmonary carcinogenesis in mice by omega-3-fatty acids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 498. doi:10.1158/1538-7445.AM2017-498

Abstract 4059: Molecular role of cytochrome P450 (CYP)1A2 in the regulation of hepatic and pulmonary CYP1A1 expression in mice exposed to 3-Methycholanthrene

Abstract 3-Methylcholanthrene (MC) is one of the most potent polycyclic aromatic hydrocarbons (PAHs) carcinogens known to date. PAHs are present in cigarette smoke, diesel exhausts, and charcoal broiled meats, etc. Cytochrome P450 (CYP) 1A enzymes play key roles in the activation of PAHs to carcinogenic metabolites. In this investigation, we tested the hypothesis that CYP1A2 plays a mechanistic role in the regulation of hepatic and pulmonary CYP1A1 by MC. Wild type (WT) (C57B6) and Cyp1a2_null mice were divided into two groups. Group I was treated with vehicle corn oil (CO) (8 ml/kg) and group II was treated with four doses of MC (100 μmol/kg), i.p. once daily for 4 days. Four animals from each group were sacrificed at 6, 12, 24, and 48 h, 8 and 15 days after MC withdrawal. The mRNA levels, protein content and enzyme activities of CYP1A1 and 1A2 were determined at different time points. In addition, the binding of MC-AHR-AHR nuclear translocator (ARNT) to the AHREs on the CYP1A1 promoter region was determined by chromatin immunoprecipitation (ChIP) assay in liver and lung tissues. In WT mice, ChIP experiments indicated that transcriptional activation of CYP1A1 was most pronounced at 6 h, followed by 12 h, but declined at later time points. In Cyp1a2_null mice, on the other hand, transcriptional activation of CYP1A1 persisted till 48 h. In lungs, AHR complex binding peak was observed at 12 h and declined later, but Cyp1a2 null mice showed more persistent binding till 48 h with a peak at 24 h. On the other hand, the expression of CYP1A1/1A2 at the mRNA, protein, and enzyme levels persisted for up to 48 h both in lung and liver tissues. These results suggest a mechanistic role for CYP1A2 in the molecular regulation of CYP1A1, and that transcriptional activation of CYP1A1 at 6-12 h is sufficient to result in sustained induction of CYP1A mRNA and protein expression for up to 48 h. These studies have important implications for carcinogenesis mediated by PAHs. Citation Format: Bhagavatula Moorthy, Paramahamsa Maturu, Lihua Wang, Weiwu Jiang. Molecular role of cytochrome P450 (CYP)1A2 in the regulation of hepatic and pulmonary CYP1A1 expression in mice exposed to 3-Methycholanthrene. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4059.

A highly sensitive BTX sensor based on electrochemically derived wall connected TiO2 nanotubes

This paper concerns development of electrochemically synthesized titanium dioxide (TiO2) nanotube array for sensing the carcinogenic aromatic hydrocarbons like benzene, toluene, and xylene (BTX) with enhanced sensitivity achievable at relatively low temperature. Structural characterizations (XRD, FESEM), revealed that variation of the H2O concentrations (1%, 2%, 5%, 8%, 10%, and 100% by volume) in mixed electrolyte, comprising of ethylene glycol (EG) and ammonium fluoride (NH4F), resulted in the formation of six distinctly different TiO2 nanoforms. Photo luminescence spectra (PL spectra) analysis authenticated different stoichiometry of these six samples. Besides, the X-ray photoelectron spectroscopy (XPS) was carried out to investigate the defect states. The XPS study enables to correlate the oxygen vacancy concentration with the anodization parameters. Among the various nanoforms, the wall connected TiO2 nanotube array was found to be the most efficient one for BTX sensing in the concentration range 1–400ppm at relatively lower operating temperatures (50–200°C). Among the three target species, benzene was found to offer the highest response magnitude followed by that of toluene and xylene at all the concentrations. The concerned sensing mechanism was also discussed correlating the experimental findings.

Chemometrics-assisted excitation–emission fluorescence spectroscopy on nylon-attached rotating disks. Simultaneous determination of polycyclic aromatic hydrocarbons in the presence of interferences

This work presents a green and very simple approach which enables the accurate and simultaneous determination of benzo[a]pyrene, dibenz[a,h]anthracene, benz[a]anthracene, and chrysene, concerned and potentially carcinogenic heavy-polycyclic aromatic hydrocarbons (PAHs) in interfering samples. The compounds are extracted from water samples onto a device composed of a small rotating Teflon disk, with a nylon membrane attached to one of its surfaces. After extraction, the nylon membrane containing the concentrated analytes is separated from the Teflon disk, and fluorescence excitation–emission matrices are directly measured on the nylon surface, and processed by applying parallel factor analysis (PARAFAC), without the necessity of a desorption step. Under optimum conditions and for a sample volume of 25mL, the PAHs extraction was carried out in 20min. Detection limits based on the IUPAC recommended criterion and relative errors of prediction were in the ranges 20–100ngL−1 and 5–7%, respectively. Thanks to the combination of the ability of nylon to strongly retain PAHs, the easy rotating disk extraction approach, and the selectivity of second-order calibration, which greatly simplifies sample treatment avoiding the use of toxic solvents, the developed method follows most green analytical chemistry principles.

Human health risk of polycyclic aromatic hydrocarbons from consumption of blood cockle and exposure to contaminated sediments and water along the Klang Strait, Malaysia

The concentration of carcinogenic poly aromatic hydrocarbons (c-PAHs) present in water and sediment of Klang Strait as well as in the edible tissue of blood cockle (Anadara granosa) was investigated.The human health risk of c-PAHs was assessed in accordance with the standards of the United States Environmental Protection Agency (US EPA). The cancer risks of c-PAHs to human are expected to occur through the consumption of blood cockles or via gastrointestinal exposure to polluted sediments and water in Kalng Strait. The non-carcinogenic risks that are associated with multiple pathways based on ingestion rate and contact rates with water were higher than the US EPA safe level at almost all stations, but the non-carcinogenic risks for eating blood cockle was below the level of US EPA concern. A high correlation between concentrations of c-PAHs in different matrices showed that the bioaccumulation of c-PAHs by blood cockles could be regarded as a potential health hazard for the consumers.

Aromatic Hydrocarbon Degrading Phyllosphere Fungi

Ambient air contains high amounts of potentially genotoxic and carcinogenic aromatichydrocarbons (AH) that originate from the petroleum related activities and coal refiningprocesses. The potential of phyllosphere organisms to oxidize these compounds into nontoxicforms has been investigated in some recent studies. This study was carried out to investigatethe presence of aromatic hydrocarbon degrading fungi in the phyllosphere of Ixora sp.,Amaranth sp., Hibiscus sp. and Ervatamia sp. which are common on roadsides close to the oilrefinery at Sapugaskanda and in several urban areas having high level of vehicular emission.Their ability to degrade the AHs phenanthrene, naphthalene, xylene and toluene wasinvestigated.Leaf samples of the four plant species were collected from five areas namely Kollonnawa,Sapugaskanda, Orugodawattha, Panchikawattha and Maradana. Then Phyllosphere fungiwere isolated into pure cultures on Czapek-Dox medium using pour plate method andidentified up to the genus level. Plate assays and spectrophotometric analysis were used toevaluate phenanthrene, naphthalene, xylene and toluene degradation ability of them as thesole source of carbon. The best fungal AH degraders were selected for furthercharacterization and identification.Isolated phyllosphere fungi, Penicillium spp, Aspergillus spp and Trichoderma spp were ableto degrade phenanthrene, naphthalene, toluene and xylene. Penicillium janthinellum wasfound to be the most effective in degrading naphthalene and phenanthrene with 98.85% and84.83% efficiency respectively. Moreover, Aspergillus niger has the highest toluenedegradation ability. The best xylene degrader; Aspergillus flavus, utilised 57.35% of xylenein the medium. Initial experiments indicated that the highest degradation of aromatichydrocarbons occurs after seven days. Therefore, in all these experiments, isolated fungalspp. were incubated for seven days in media supplemented with aromatic hydrocarbons.While traditional chemical and physical remediation techniques are currently becoming lesseffective from environmental and economical point of view, there is an increasing interest inbioremediation. According to the finding of the present investigation Penicillium spp. andAspergillus spp. are having the potential to be used in effective bioremediation strategies inthe removal of AH. Their ability to degrade these compounds while surviving underenvironmental stresses makes them suitable candidates for bioremediation.

Abstract 1502: Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study.

Abstract Background: In the United States, 10-15% of lung cancer victims are lifelong never smokers. Non-smoking related lung cancer alone ranks as the 6th most frequently diagnosed cancer. The etiological factors for non-smoking lung cancer are unclear. Although strong evidence supports a major role for polycyclic aromatic hydrocarbon (PAH) as causes of lung cancer in smokers, epidemiological studies prospectively investigating biomarkers of PAH and volatile organic carcinogens in relation to lung cancer risk among never smokers are lacking. Methods: A nested case-control study of lung cancer among never smokers was conducted within the Shanghai Cohort Study, a prospective cohort of 18,244 Chinese men aged 45-64 years at enrollment during 1986-1989. After more than 20 years of follow-up, we identified 96 incident lung cancer cases among never smokers. For each case, we randomly chose one control among cohort participants who were never smokers. The control was matched to the index case by age (±2 years), date of urine collection (±1 month) and neighborhood of residence. We quantified urinary free cotinine, 3-hydroxyphenanthrene (3-OH-Phe), total hydroxyphenanthrenes (the sum of 1-, 2-, 3-, and 4-OH-Phe) (total OH-Phe), r-1,t-2,3,c-4-tetrahdroxy-1,2,3,4-tetrahydrophenanthrene (PheT), mercapturic acid metabolites of acrolein [3-hydroxypropyl mercapturic acid (HPMA)], benzene [S-phenyl mercapturic acid (SPMA)], crotonaldehyde [4-hydroxybut-2-yl mercapturic acid (HBMA)], and ethylene oxide [2-hydroxyethyl mercapturic acid (HEMA)]. Self-reported never smokers whose urinary free cotinine was greater than 20 ng/ml were excluded from the present analysis for their potential use of tobacco. The odds ratio (OR) and 95% confidence interval (CI) for lung cancer for each urinary biomarker was estimated using an unconditional logistic regression method. Results: Among never smokers, urinary levels of all 3 measured PAH biomarkers were statistically significantly higher in cases than controls. The geometric means (pmol/mg creatinine) of total OH-Phe, 3-OH-Phe and PheT were 19.10 (in cases) vs 16.08 (in controls) (P = 0.017); 6.64 vs 5.44 (P = 0.011); and 19.84 vs 16.10 (P = 0.035), respectively. Compared with the lowest quartile, ORs (95% CIs) for lung cancer for the highest quartile were 2.59 (1.01-6.65) for total OH-Phe, 3.10 (1.12-7.75) for 3-OH-Phe, and 2.98 (1.13-7.87) for PheT (all Ptrend <0.05). There was no statistically significant difference in urinary levels of HPMA, SPMA, HBMA and HEMA between cases and controls. Conclusion: This is the first prospective study that demonstrates a positive association between urinary biomarkers of PAH and lung cancer risk among never smokers. Given its ubiquitous presence in the environment, PAH could account for large proportion of non-smoking related lung cancer. 1 Citation Format: Jian-Min Yuan, Yu-Tang Gao, Sharon Murphy, Steven G. Carmella, Renwei Wang, Heather H. Nelson, Stephen S. Hecht. Urinary biomarkers of polycyclic aromatic hydrocarbon and volatile organic carcinogens in relation to lung cancer development in lifelong never smokers - The Shanghai Cohort Study. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1502. doi:10.1158/1538-7445.AM2013-1502

유사휘발유 사용에 의한 BTX 배출량 추정

The increasing consumption of pseudo-petroleum products (PPP) has been disturbing the national petroleum market. The use of PPP lead to tax evasion, disturbance of sound trading principles, component corrosion of cars, and explosion accident. Also, PPP have emitted hazardous air pollutants (HAP) including the carcinogenic aromatic hydrocarbons, PAHs and aldehydes more than regular-petroleum products. It thus has potentials to cause many environmental and health care problems. In this study, benzene, toluene and xylene emissions from road transport vehicles due to the use of pseudo-gasoline are estimated for the year 2008. The results of our study provide emission estimates of benzene, toluene and xylene for the year as 405, 1,711, 717 tonne/yr, respectively for regular-gasoline. BTX emissions are calculated as 452~515, 1,882~2,264 and 732~752 tonne/yr when the amount of pseudo-gasoline is estimated to account for 6~13% for regular-gasoline consumption. BTX emissions increased as much as 12~27, 10~32, 2~5% by using pseudo-gasoline. It is found that the pseudo-gasoline should be the key component to produce HAP in urban area.

Potential roles of fibroblast growth factor-9 in the benzo(a)pyrene-induced invasion in vitro and the metastasis of human lung adenocarcinoma

Fibroblast growth factor (FGF)-9 belongs to the FGF family which modulate cell proliferation, differentiation, and motility. Benzo(a)pyrene is a polycyclic aromatic hydrocarbon (PAH) and ubiquitous environmental carcinogen present in automobile exhaust, cigarette smoke, and foods. The major purposes of this study were to explore the roles of FGF-9 in the benzo(a)pyrene-induced lung cancer invasion in vitro and the metastatic development of lung adenocarcinoma in human. The data of RT-PCR analysis indicated that treatments of human lung adenocarcinoma CL5 cells with benzo(a)pyrene and a PAH mixture motorcycle exhaust particulate (MEP) extracts increased FGF-9 mRNA expression. The increased expression was blocked by cotreatments with a p38 mitogen-activated protein kinase inhibitor SB202190 and an extracellular signal-regulated kinase inhibitor PD98059. The results of immunoblot analysis and Matrigel assay showed that benzo(a)pyrene and MEP extracts produced a concomitant induction of FGF-9 protein and invasive ability of CL5 cells. The benzo(a)pyrene- and MEP-induced invasion was suppressed by FGF-9 neutralizing antibodies. The results of immunohistochemistry analysis of human lung adenocarcinoma specimens showed that FGF-9 protein was detected in the adenocarcinoma cells but not in normal epithelium. FGF-9 staining intensity was positively correlated with status of disease and degree of lymph node metastasis in these lung adenocarcinomas. These present findings suggest that FGF-9 has potential roles in benzo(a)pyrene-induced CL5 cell invasion and human lung adenocarcinoma metastasis.

Topological influences on the carcinogenicity of aromatic hydrocarbons. I. The bay region geometry

Graph theory provides a means for obtaining mathematical measures of molecular topological features. A graph theoretical atomic index is described which expresses the relative connectivity of an atom to the remainder of a molecular structure. This index allows an alternative and complementary interpretation of concepts described earlier by J. P. Lowe and B. D. Silverman [J. Am. Chem. Soc. 1981, 103, 2852-2855 (1981)] regarding the ease of formation and stability of “bay region” triol carbonium ions. Bay region carbonium ions are more stable because they form at positions more strongly connected to aromatic structures than alternative sites.

Topological influences on the carcinogenicity of aromatic hydrocarbons. II. Substituent effects

Graph-theoretical analysis reveals that topological considerations provide a helpful guide to understanding substituent effects on the carcinogenic activities of aromatic hydrocarbons. If the aromatic system is considered as a network, the influence of methyl and hydroxyl groups at positions remote from the bay region depends on whether they are at strongly or weakly connected positions. Strongly connected methyl substituents tend to enhance carcinogenic potency, whereas strongly connected phenolic groups tend to decrease it.

Simulated ab initio molecular orbital calculations of large polynuclear aromatic hydrocarbons

Molecular orbital electronic structure calculations for twelve polynuclear aromatic hydrocarbons were performed by the samo method. Results indicate that the carcinogenicity of such aromatic hydrocarbons is related to a K-region π-bond order greater than 0.340. There is no correlation with δ-bond order or overall charge density, perhaps accounting for the success of earlier theoretical treatments based on the π-electron model. Exceptions to a simple K-region treatment are discussed in terms of other models for carcinogenic activity.

Overexpression of antioxidant enzymes in ApoE-deficient mice suppresses Benzo(a)pyrene-accelerated atherosclerosis

The carcinogenic polycylic aromatic hydrocarbon, benzo(a)pyrene (BaP), has been shown to generate reactive oxygen species (ROS) and accelerate the development of atherosclerosis. To assess the causal role of BaP-generated ROS in this process, we evaluated atherosclerotic metrics in apolipoprotein E-deficient ( ApoE −/− ) mice with or without overexpression of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and/or catalase. Without BaP, aortic atherosclerotic lesions were smaller in ApoE −/− mice overexpressing catalase or both Cu/Zn-SOD and catalase than in those overexpressing neither or Cu/Zn-SOD only. After treating with BaP or vehicle for 24 weeks, mean lesion sizes in the aortic tree and aortic root of ApoE −/− mice were increased by approximately 60% and 40%, respectively. BaP also increased the levels of oxidized lipids in the aortic tree of ApoE −/− mice and increased the frequency of advanced lesions. In contrast, BaP did not significantly alter lipid peroxidation levels or atherosclerotic lesions in the aortas of ApoE −/− mice overexpressing Cu/Zn-SOD and/or catalase. Overexpression of Cu/Zn-SOD and/or catalase also inhibited BaP-induced expression of cell adhesion molecules in aortas and endothelial cells, and reduced BaP-induced monocyte adhesion to endothelial cells. These observations, together with the functions of catalase and Cu/Zn-SOD to scavenge hydrogen peroxide and superoxide anions, implicate a causal role of ROS in the pathogenesis of BaP-induced atherosclerosis.

Surface IR applied to rapid and direct immunosensing of environmental pollutants

This paper describes the elaboration of a model immunosensor monitored by polarization modulation reflection absorption infrared spectroscopy (PM-RAIRS) and quartz crystal microbalance (QCM-D), as well as its reactivity using PM-RAIRS as transduction technique. To prove its relevance, this immunosensor was applied to the detection of benzo[a]pyrene (BaP), a carcinogenic polycylic aromatic hydrocarbon. Very few immunoassays, and even fewer immunosensors, have been described for the assay of BaP, making it an interesting target for analytical device development. The PM-RAIRS immunosensor was constructed on planar gold-coated sensors functionalized with cystamine then glutaraldehyde. Antibodies were immobilized through their affinity to protein G, covalently coupled to the aldehyde layer. In a first stage, a model mouse IgG was utilized to optimize the elaboration parameters; then, a monoclonal anti-PAH antibody was used and detection tests were performed, monitored by PM-RAIRS. The successive functionalization steps were monitored by PM-RAIRS and QCM-D. The binding of the proteins to gold surface, their saturation coverages and association constants, as well as their capture efficiencies were discussed. BaP capture by the antibody layer was evidenced by the appearance of a new ν(C–H) band at 3039 cm −1 typical of aromatic C–H bonds. The integrated area of this band varied linearly with the BAP concentration within the range of tested concentrations, with a limit of detection close to 3 μM. This represents the first example of direct, label-free immunodetection of a low molecular weight molecule by PM-RAIRS transduction. The simplicity and the rapid response of this IR sensor make it already very worthwhile to preliminary on-site measurements.

Inhibition of human cytochrome p450 1b1 further clarifies its role in the activation of dibenzo[a,l]pyrene in cells in culture

Metabolic activation and DNA adduct formation of the carcinogenic aromatic hydrocarbon dibenzo[a,l]pyrene (DBP) was investigated in human mammary carcinoma MCF-7 cells and human cytochrome P450 (CYP) 1B1-expressing Chinese hamster V79 cells in culture. It has been shown that DBP is metabolically activated to DNA-binding diol epoxides both in vitro and in vivo. To further establish the role of human CYP1B1 in the activation of DBP, both cell lines were cotreated with DBP and a selective chemical inhibitor of CYP1B1, 2,4,3' ,5'-tetramethoxy-stilbene (TMS). Results from DBP-DNA adduct analyses revealed the complete inhibition of DNA binding when cells were cotreated with DBP and TMS in comparison to DBP alone. Inactivation of CYP1B1 by TMS was also demonstrated through a decrease in the 7-ethoxyresorufin O-deethylase (EROD) activity in microsomes isolated from these cells. Emodin, 3-methyl-1,6,8-trihydroxyanthraquinone, an active ingredient of an herb, has been recently shown of being able to induce CYP1 gene expression. Examination of human CYP1B1 induction and EROD activity confirmed an increase in protein levels upon cotreatment with emodin and DBP. Despite increases in protein levels and enzyme activity, there was no significant change in DBP-DNA binding levels at very low substrate concentrations (17 nM). The data obtained in this study emphasize the central role of CYP1B1 in the activation of DBP in human cells in culture.

Modulation of Biological Regulatory Networks During Nephrogenesis

Mesenchymal-to-epithelial transition is an important biological event during the course of renal cell differentiation as condensing mesenchyme gives rise to tubuloepithelial structures. Wilms' tumor suppressor gene (Wt1) has been identified as a master regulator of the complex genetic events that mediate mesenchymal transdifferentiation. Evidence is summarized here showing that the tightly regulated series of genetic and biochemical events during nephrogenesis is disrupted by superactivation of aryl hydrocarbon receptor (Ahr) by benzo(a)pyrene (BaP), a ubiquitous polycyclic aromatic hydrocarbon and renal carcinogen (). Nephron formation is inhibited by BaP, a response that involves inhibition of metanephric cell differentiation and shifts in the relative abundance of Wt1 splice variants. A systems biology paradigm that combined approaches from genomics, transcriptomics, and bioinformatics revealed that the global response of murine metanephric cultures to BaP involves downregulation of Ahr and disruption of downstream targets of Wt1. Discrete networks of genetic regulation were resolved using Boolean idealizations and included genes involved in renal cell differentiation and metabolic control. This work has established a role for Ahr in renal cell differentiation and kidney development and resolved putative molecular interactions between Ahr and Wt1.

Dermal bioavailability of benzo[a]pyrene on lampblack: Implications for risk assessment

Lampblack is the principal source of contamination in soils at manufactured gas plant (MGP) sites where oil was used as the feedstock. Risks and cleanup criteria at these sites are determined primarily by the total carcinogenic polynuclear aromatic hydrocarbon (PAH) content, particularly the concentration of benzo[a]pyrene (BaP). Dermal contact with soils at oil-gas MGP sites is a significant component of the overall risks. Seven samples were collected from oil-gas MGP sites and the steady-state dermal fluxes were measured over 96 h in vitro. The standard dermal bioassay technique (in which 3H-BaP is added to the soil matrix) was modified to allow direct measurement of the dermal absorption of the native BaP in the samples. The experimentally derived dermal absorption factors for BaP were 14 to 107 times lower than the default assumption of 15% over 24 h (55-fold lower on average). The dermal fluxes were correlated positively to the total BaP and total carbon concentrations. The measured dermal absorption factors were compared to the default risk-assessment calculations for all seven samples. The calculated excess cancer risk was reduced as a result of using the measured absorption factors by 97% on average (with reductions ranging from 93 to 99%). This work indicates the risks at oil-gas MGP sites currently are overestimated by one to two orders of magnitude, and provides a protocol for the testing and data analysis needed to generate site-specific cleanup levels.