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BACKGROUND: The Superfund Research Program (SRP) is an academically based, multidisciplinary, translational research program that for 25 years has sought scientific solutions to health and environmental problems associated with hazardous waste sites. SRP is coordinated by the National Institute of Environmental Health Sciences (NIEHS). It supports multi-project grants, undergraduate and postdoctoral training programs, individual research grants, and Small Business Innovation Research (SBIR) and Technology Transfer Research (STTR) grants. RESULTS: SRP has had many successes: discovery of arsenic's toxicity to the developing human central nervous system; documentation of benzene toxicity to hematologic progenitor cells in human bone marrow; development of novel analytic techniques such as the luciferase expression assay and laser fragmentation fluorescence spectroscopy; demonstration that PCBs can cause developmental neurotoxicity at low levels and alter the genomic characteristics of sentinel animals; elucidation of the neurodevelopmental toxicity of organophosphate insecticides; documentation of links between antimicrobial agents and alterations in hormone response; discovery of biological mechanisms through which environmental chemicals may contribute to obesity, atherosclerosis, diabetes, and cancer; tracking the health and environmental effects of the attacks on the World Trade Center and Hurricane Katrina; and development of novel biological and engineering techniques to facilitate more efficient and lower-cost remediation of hazardous waste sites. CONCLUSION: SRP must continue to address the legacy of hazardous waste in the United States, respond to new issues caused by rapid advances in technology, and train the next generation of leaders in environmental health science while recognizing that most of the world's worst toxic hot spots are now located in low- and middle-income countries. http://dx.doi.org/10.1289/ehp.1409247, Introduction Twenty-five years ago, the U.S. Congress first set aside funds to address fundamental research needs for the nation's hazardous waste problem with the Comprehensive Environmental Response, Compensation, and Liability [...]

A rapid, mild and scalable tellurium-mediated cycloaromization reaction is demonstrated. The reaction conditions tolerate the typical functionality required for solubilization of cycloaromization based on polycyclic aromatic compounds and allow the large-scale preparation of technologically important fused aromatic systems in generally good yield.

Advances in public health over the past century have led to dramatic improvements in longevity and quality of life in the United States [1]. Advances in nutrition, including research in [...]

It has been possible to prepare two functionalized pentacene derivatives and to study the impact of this functionalization on the solid-state ordering and the electronic characteristics of the resulting chemicals. There was found to be substantial conductivity improvement by controlling the arrangement of the molecules in the solid state.

Quantum dots (Qdots) are semiconductor nanoparticles with size-tunable fluorescence capabilities with diverse applications. Qdots typically contain cadmium or other heavy metals, hence raising concerns of their potential toxicity, especially in occupational settings where inhalation of nanomaterials may increase the risk of lung disease. Accordingly, we assessed the effects of tri- n-octylphosphine oxide, poly(maleic anhydride- alt-1-tetradecene) (TOPO-PMAT) coated CdSe/ZnS Qdots on mouse lung epithelial cells and macrophages. Mouse tracheal epithelial cells (MTEC), grown as organotypic cultures, bone marrow-derived macrophages (BMDM), and primary alveolar macrophages (AM) were derived from C57BL/6J or A/J mice and treated with TOPO-PMAT CdSe/ZnS Qdots (10-160 nM) for up to 24 h. Cadmium analysis showed that Qdots remained in the apical compartment of MTEC cultures, whereas they were avidly internalized by AM and BMDM, which did not differ between strains. In MTEC, Qdots selectively induced expression (mRNA and protein) of neutrophil chemokines CXCL1 and CXCL2 but only low to no detectable levels of other factors assessed. In contrast, 4 h exposure to Qdots markedly increased expression of CXCL1, IL6, IL12, and other pro-inflammatory factors in BMDM. Higher inflammatory response was seen in C57BL/6J than in A/J BMDM. Similar expression responses were observed in AM, although overall levels were less robust than in BMDM. MTEC from A/J mice were more sensitive to Qdot pro-inflammatory effects while macrophages from C57BL/6J mice were more sensitive. These findings suggest that patterns of Qdot-induced pulmonary inflammation are likely to be cell-type specific and genetic background dependent. [ABSTRACT FROM AUTHOR]

Long-term therapy with certain drugs, especially cytochrome P450 (P450; CYP)-inducing agents, confers an increased risk of osteomalacia that is attributed to vitamin D deficiency. Human CYP24A1, CYP3A4, and CYP27B1 catalyze the inactivation and activation of vitamin D and have been implicated in the adverse drug response. In this study, the inducibility of these enzymes and monohydroxylation of 25-hydroxyvitamin D3 (25OHD3) were evaluated after exposure to P450-inducing drugs. With human hepatocytes, treatment with phenobarbital, hyperforin, carbamazepine, and rifampin significantly increased the levels of CYP3A4, but not CYP24A1 or CYP27B1 mRNA. In addition, rifampin pretreatment resulted in an 8-fold increase in formation of the major metabolite of 25OHD3, 4β,25(OH)2D3. This inductive effect was blocked by the addition of 6′,7′-dihydroxybergamottin, a selective CYP3A4 inhibitor. With human renal proximal tubular HK-2 cells, treatment with the same inducers did not alter CYP3A4, CYP24A1, or CYP27B1 expression. 24R,25(OH)2D3 was the predominant monohydroxy metabolite produced from 25OHD3, but its formation was unaffected by the inducers. With healthy volunteers, the mean plasma concentration of 4β,25(OH)2D3 was increased 60% ( p < 0.01) after short-term rifampin administration. This was accompanied by a statistically significant reduction in plasma 1α,25(OH)2D3 (−10%; p = 0.03), and a nonsignificant change in 24R,25(OH)2D3 (−8%; p = 0.09) levels. Further analysis revealed a negative correlation between the increase in 4β,25(OH)2D3 and decrease in 1α,25(OH)2D3 levels. Examination of the plasma monohydroxy metabolite/25OHD3 ratios indicated selective induction of the CYP3A4-dependent 4β-hydroxylation pathway of 25OHD3 elimination. These results suggest that induction of hepatic CYP3A4 may be important in the etiology of drug-induced osteomalacia. © 2013 American Society for Bone and Mineral Research. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are unique semi-conductor fluorescent nanoparticles with potential uses in a variety of biomedical applications. However, concerns exist regarding their potential toxicity, specifically their capacity to induce oxidative stress and inflammation. In this study we synthesized CdSe/ZnS core/shell QDs with a tri-n-octylphosphine oxide, poly(maleic anhydride-alt-1-tetradecene) (TOPO-PMAT) coating and assessed their effects on lung inflammation in mice. Previously published in vitro data demonstrated these TOPO-PMAT QDs cause oxidative stress resulting in increased expression of antioxidant proteins, including heme oxygenase, and the glutathione (GSH) synthesis enzyme glutamate cysteine ligase (GCL). We therefore investigated the effects of these QDs in vivo in mice deficient in GSH synthesis (Gclm +/− and Gclm −/− mice). When mice were exposed via nasal instillation to a TOPO-PMAT QD dose of 6 µg cadmium (Cd) equivalents/kg body weight, neutrophil counts in bronchoalveolar lavage fluid (BALF) increased in both Gclm wild-type (+/+) and Gclm heterozygous (+/−) mice, whereas Gclm null (−/−) mice exhibited no such increase. Levels of the pro-inflammatory cytokines KC and TNFα increased in BALF from Gclm +/+ and +/− mice, but not from Gclm −/− mice. Analysis of lung Cd levels suggested that QDs were cleared more readily from the lungs of Gclm −/− mice. There was no change in matrix metalloproteinase (MMP) activity in any of the mice. However, there was a decrease in whole lung myeloperoxidase (MPO) content in Gclm −/− mice, regardless of treatment, relative to untreated Gclm +/+ mice. We conclude that in mice TOPO-PMAT QDs have in vivo pro-inflammatory properties, and the inflammatory response is dependent on GSH synthesis status. Because there is a common polymorphism in humans that influences GCLM expression, these findings imply that humans with reduced GSH synthesis capabilities may be more susceptible to the pro-inflammatory effects of QDs. [ABSTRACT FROM AUTHOR]

Because of their unique optical properties, quantum dots (QDs) have become a preferred system for ultrasensitive detection and imaging. However, since QDs commonly contain Cd and other heavy metals, concerns have been raised regarding their toxicity. QDs are thus commonly synthesised with a ZnS cap structure and/or coated with polymeric stabilisers. We recently synthesised amphiphilic polymer-coated tri-n-octylphosphine oxide - poly(maleic anhydride-alt-1-tetradecene (TOPO-PMAT) QDs, which are highly stable in aqueous environments. The effects of these QDs on viability and stress response in five cell lines of mouse and human origins are reported here. Human and mouse macrophages and human kidney cells readily internalised these QDs, resulting in modest toxicity. TOPO-PMAT QD exposure was highly correlated with the induction of the stress response protein heme oxygenase-1 (HMOX1). Other stress biomarkers (glutamate cysteine ligase modifier subunit, NAD(P)H, necrosis) were only moderately affected. HMOX1 may thus be a useful biomarker of TOPO-QDOT QD exposure across cell types and species. [ABSTRACT FROM AUTHOR]

Kidney disease is a public health problem that affects more than 20 million people in the US adult population, yet little is understood about the impact of kidney disease on drug disposition. Consequently there is a critical need to be able to model the human kidney and other organ systems, to improve our understanding of drug efficacy, safety, and toxicity, especially during drug development. The kidneys in general, and the proximal tubule specifically, play a central role in the elimination of xenobiotics. With recent advances in molecular investigation, considerable information has been gathered regarding the substrate profiles of the individual transporters expressed in the proximal tubule. However, we have little knowledge of how these transporters coupled with intracellular enzymes and influenced by metabolic pathways form an efficient secretory and reabsorptive mechanism in the renal tubule. Proximal tubular secretion and reabsorption of xenobiotics is critically dependent on interactions with peritubular capillaries and the interstitium. We plan to robustly model the human kidney tubule interstitium, utilizing an ex vivo three-dimensional modular microphysiological system with human kidney-derived cells. The microphysiological system should accurately reflect human physiology, be usable to predict renal handling of xenobiotics, and should assess mechanisms of kidney injury, and the biological response to injury, from endogenous and exogenous intoxicants. [ABSTRACT FROM AUTHOR]

The article presents a study on Cytochrome P-450 1A2 (CYP1A2), a biotransformation enzyme that triggers several procarcinogens induced by cruciferous and inhibited by apiaceous vegetable consumption in the U.S. Crossover feeding trial was done to get the effects of the vegetable intake and the response variations on genotypes determined by urine caffeine tests. The results indicate complex interaction among dietary patterns, sex, genetic variation, and modulation of biotransformation.

This review examines the large body of toxicological and epidemiological information on human exposures to chlorpyrifos, with an emphasis on the controversial potential for chlorpyrifos to induce neurodevelopmental effects at low doses. The results of this review demonstrate that the use of urinary 3,5,6-trichlorpyridinol (TCPy), a metabolite of chlorpyrifos as a biomarker of nonoccupational exposure is problematic and may overestimate nonoccupational exposures to chlorpyrifos by 10-to 20-fold because of the widespread presence of both TCPy and chlorpyrifos-methyl in the food supply. Current “background” (nonoccupational) levels of exposure to chlorpyrifos are several orders of magnitude lower than those required to inhibit plasma cholinesterase activity, which is a more sensitive target than nervous system cholinesterase. However, several in vitro studies have identified putative neurodevelopmental mechanisms that are altered at concentrations of chlorpyrifos below those that inhibit cholinesterases. Although one human cohort study reported an association between maternal and cord blood chlorpyrifos levels and several measures of neurodevelopment, two other cohort studies that utilized urinary TCPy as a surrogate for chlorpyrifos exposure did not demonstrate an association. Although the weight of the scientific evidence demonstrates that current levels of chlorpyrifos exposure will not have any adverse effects on neurodevelopment that might result from inhibition of nervous system cholinesterases, several recent studies propose alternative mechanisms. Thus, further in vivo investigation on neurodevelopment in an appropriate animal model is needed; additional epidemiological studies may be warranted if a suitable, chlorpyrifos-exposed cohort can be identified and more rigorous measures of exposure are utilized. [ABSTRACT FROM AUTHOR]

The article reports on results of a population-based case-control study of serum organochlorine pesticide residues and risk of testicular germ cell carcinoma (TGCC) among male residents of three Washington State counties. A description of the experimental set-up and measurement method is provided. The study showed no clear patterns between TGCC risk and concentrations of any of the organochlorines measured.

Aflatoxin B1 (AFB1) is a human hepatotoxin and hepatocarcinogen produced by the mold Aspergillus flavus. In humans, AFB1 is primarily bioactivated by cytochrome P450 1A2 (CYP1A2) and 3A4 to a genotoxic epoxide that forms N7-guanine DNA adducts. A series of yeast haploid mutants defective in DNA repair and cell cycle checkpoints were transformed with human CYP1A2 to investigate how these DNA adducts are repaired. Cell survival and mutagenesis following aflatoxin B1 treatment was assayed in strains defective in nucleotide excision repair (NER) (rad14), postreplication repair (PRR) (rad6, rad18, mms2, and rad5), homologous recombinational repair (HRR) (rad51 and rad54), base excision repair (BER) (apn1 apn2), nonhomologous end-joining (NHEJ) (yku70), mismatch repair (MMR) (pms1), translesion synthesis (TLS) (rev3), and checkpoints (mec1-1, mec1-1 rad53, rad9, and rad17). Together our data suggest the involvement of homologous recombination and nucleotide excision repair, postreplication repair, and checkpoints in the repair and/or tolerance of AFB1-induced DNA damage in the yeast model. Rev3 appears to mediate AFB1-induced mutagenesis when error-free pathways are compromised. The results further suggest unique roles for Rad5 and abasic endonuclease-dependent DNA intermediates in regulating AFB1-induced mutagenicity. [ABSTRACT FROM AUTHOR]

The antioxidant tripeptide glutathione has been proposed to be important in defense against oxidative stress and heavy metal toxicity. We evaluated alterations in glutathione regulation and synthesis associated with low-level chronic methylmercury (MeHg) exposure in the developing mouse fetus. Female C57Bl/6 mice were given 0, 3, or 10 ppm MeHg in the drinking water for 2 weeks prior to breeding and throughout pregnancy. Fetuses were collected on gestational days (gd) 12 and 16. Total glutathione, reduced glutathione (GSH), oxidized glutathione (GSSR), and glutamate-L-cysteine ligase (Glcl) activity were assessed in yolk sacs and fetuses at gd 16. Western and Northern blots for Glcl-catalytic (Glclc) and Glcl-regulatory (Glclr) subunits were performed on gd 12 and gd 16 fetuses. There were no changes in total glutathione in gd 16 mouse fetuses with exposure, but there were dose-related decreases in GSH and increases in GSSR. In contrast, visceral yolk sacs exhibited an increase in total glutathione in the low-dose groups, but no changes in the high-dose group. There were no changes in Glcl activity in fetuses, but there was a 2-fold increase in Glcl activity in yolk sacs from both low-dose and high-dose groups. There was a 2-fold induction in Glclc mRNA and protein in the gd 16 yolk sacs at both 3 and 10 ppm MeHg. No treatment-related changes in Glclr protein in either gd 12 or gd 16 yolk sacs or fetuses were found. Thus, the yolk sac is capable of up-regulating Glclc and GSH synthetic capacity in response to MeHg exposure. This increase appears to be sufficient to resist MeHg-induced GSH depletion in the yolk sac; however fetal glutathione redox status is compromised with exposure to 10 ppm MeHg. [ABSTRACT FROM PUBLISHER]

Mice are resistant to the carcinogenic effects of the mycotoxin aflatoxin B1 (AFB1) because they constitutively express an alpha-class glutathione S-transferase (mGSTA3-3) that has high (∼200,000 pmol/min/mg) activity toward aflatoxin B1-8,9-epoxide (AFBO). Rats do not constitutively express a GST with high AFBO-conjugating activity and are sensitive to AFB1-induced hepatocarcinogenesis. Constitutively expressed human hepatic alpha-class GSTs (hGSTA1-1 and hGSTA2-2) possess little or no AFBO-detoxifying activity (<2 pmol/min/mg). Recently, we found that the nonhuman primate, Macaca fascicularis (Mf), exhibits significant (∼300 pmol/min/mg) constitutive hepatic GST activity towards AFBO. To determine which specific GST isoenzyme(s) is (are) responsible for this activity, Mf GSTs were purified from liver tissue and characterized and, Mf mu-class GST cDNAs were cloned by reverse transcriptase-coupled polymerase chain reaction (RT-PCR). Purification by glutathione agarose (GSHA) affinity chromatography yielded a protein, GSHA-GST, that exhibited relatively high AFBO-conjugating activity (239 pmol/min/mg) compared to other GST-containing peaks. Western blotting and enzymatic activity analyses revealed that GSHA-GST belongs to the mu class. Two distinct mu-class GST cDNAs, mfaGSTM1 (GenBank accession # AF200709) and mfaGSTM2 (GenBank accession # AF200710), were generated by RT-PCR. CDNA-derived amino acid sequence analysis revealed that mfaGSTM1 and mfaGSTM2 share 97% and 96% homology with the human mu-class GSTs hGSTM4 and hGSTM2, respectively. In contrast to recombinant mfaGSTM1-1, which had no detectable AFBO-conjugating activity, mfaGSTM2-2 exhibited this activity at 333 pmol/min/mg. Activity profiles for the stereoisomers exo- and endo-AFBO, and of 1-chloro-2,4-dinitrobenzene of the purified protein GSHA-GST and recombinant mfaGSTM2-2, suggested that they are two distinct enzymes. Our results indicate that, in contrast to rodents, mu-class GSTs are responsible for the majority of AFBO-conjugating activity in the liver of Macaca fascicularis. [ABSTRACT FROM PUBLISHER]

Following aflatoxin B1 (AFB) exposure, rats readily develop liver tumors. However, treatment of rats with a variety of compounds, including the synthetic dithiolthione oltipraz and the antioxidant ethoxyquin, protects these rodents from AFB-induced hepatocarcinogenesis. Several epidemiological studies strongly suggest that AFB is also a causative agent of liver cancer in humans. However, relatively little is known about the efficacy of cancer chemoprevention in human and non-human primates. To this end, we examined the effects of chemopreventive agents on AFB metabolism in non-human primates. Hepatic aflatoxin B1 metabolism profiles of macaque (Macaca nemestrina) and marmoset (Callithrix jacchus) monkeys were determined and compared to humans. Quantitatively, the oxidative metabolism of this mycotoxin was similar in the three primate species. In contrast to macaques, both humans and marmosets lacked AFB-glutathione conjugating activity. It was concluded that marmosets resembled human AFB metabolism more closely than the macaques, and therefore, marmoset monkeys were chosen for this study. Eleven adult male marmosets were randomly assigned to three groups. Animals received the synthetic dithiolthione oltipraz, the antioxidant ethoxyquin, or vehicle only. In addition, two single doses of AFB were also administered orally before and after animals were treated with aforementioned compounds. Both oltipraz and ethoxyquin induced aflatoxin B1-glutathione conjugating activity in the livers of some but not all marmosets. In addition, 10 μM oltipraz inhibited cytochrome P450-mediated activation of AFB to the ultimate carcinogenic metabolite, aflatoxin B1-8,9-epoxide,in vitro, up to 51%. Furthermore, animals treated in vivo with oltipraz, but not ethoxyquin, exhibited a significant reduction (53% average) in AFB-DNA adduct formation relative to the control animals (p < 0.05). Together, our data suggest that chemoprevention is also effective in primates; however, most likely to a lesser degree than in rodents. [ABSTRACT FROM PUBLISHER]

The article discusses the major features of the glutathione S-transferases (GST), a multi-gene family of enzymes involved in the detoxification or activation of a wide variety of chemicals, and their role in toxicology. The soluble GST constitute as much as 4% of the total soluble protein in the liver of humans and rodents. The enzymes help in the detoxification of endogenous products of lipid peroxidation, such as 4-hydroxy-2-nonenal, and certain GST help activate xenobiotics to reactive forms while detoxifying others.