Publications by authors named "Cliff Elcombe"

Derisking xenobiotic-induced nongenotoxic carcinogenesis (NGC) represents a significant challenge during the safety assessment of chemicals and therapeutic drugs. The identification of robust mechanism-based NGC biomarkers has the potential to enhance cancer hazard identification. We previously demonstrated Constitutive Androstane Receptor (CAR) and WNT signaling-dependent up-regulation of the pluripotency associated Dlk1-Dio3 imprinted gene cluster noncoding RNAs (ncRNAs) in the liver of mice treated with tumor-promoting doses of phenobarbital (PB).

View Article and Find Full Text PDF

The need for non-animal data to assess skin sensitisation properties of substances, especially cosmetics ingredients, has spawned the development of many in vitro methods. As it is widely believed that no single method can provide a solution, the Cosmetics Europe Skin Tolerance Task Force has defined a three-phase framework for the development of a non-animal testing strategy for skin sensitization potency prediction. The results of the first phase – systematic evaluation of 16 test methods – are presented here.

View Article and Find Full Text PDF

Registration of new plant protection products (e.g., herbicide, insecticide, or fungicide) requires comprehensive mammalian toxicity evaluation including carcinogenicity studies in two species.

View Article and Find Full Text PDF

The potential to differentiate human embryonic stem cells (hESCs) in vitro to provide an unlimited source of human hepatocytes for use in biomedical research, drug discovery, and the treatment of liver diseases holds great promise. Here we describe a three-stage process for the efficient and reproducible differentiation of hESCs to hepatocytes by priming hESCs towards definitive endoderm with activin A and sodium butyrate prior to further differentiation to hepatocytes with dimethyl sulfoxide, followed by maturation with hepatocyte growth factor and oncostatin M. We have demonstrated that differentiation of hESCs in this process recapitulates liver development in vivo: following initial differentiation, hESCs transiently express characteristic markers of the primitive streak mesendoderm before turning to the markers of the definitive endoderm; with further differentiation, expression of hepatocyte progenitor cell markers and mature hepatocyte markers emerged sequentially.

View Article and Find Full Text PDF

Perfluorooctanesulfonate (PFOS) is a widely disseminated persistent compound found at low (part-per-billion) concentrations in serum and liver samples from humans and fish-eating wildlife. This study investigated the hypotheses that early hepatocellular peroxisomal proliferation and hepatic cellular proliferation are factors in chronic liver response to dietary dosing, that lowering of serum total cholesterol is an early clinical measure of response to treatment, and that liver and serum PFOS concentrations are proportional to dose and cumulative dose after sub-chronic treatment. PFOS was administered in diet as the potassium salt at 0, 0.

View Article and Find Full Text PDF

Ammonium perfluorooctanoate (APFO) is a processing aid in the production of fluoropolymers that has been shown to have a long half-life in human blood. To understand the potential toxicological response of primates, groups of male cynomolgus monkeys were given daily po (capsule) doses of either 0, 3, 10, or 30 (reduced to 20) mg/kg/day for 26 weeks. Two monkeys from each of the control and 10 mg/kg/day dose groups were observed for 90 days after the last dose.

View Article and Find Full Text PDF