Health risks from exposure to chemicals in clothing - Non-regulated halogenated aromatic compounds.

The objective of the present study was to investigate some commonly detected halogenated textile pollutants for their bioavailability and hazardous properties. Release into artificial sweat and skin absorption in vitro were examined as well as mutagenic effects by Ames test, and skin-sensitizing properties from a peptide reactivity assay combined with a cell test. All investigated compounds were shown to migrate from the textile into sweat and be absorbed by the skin, although to a different extent. The experimental values for migration were found to be up to 390 times higher compared to literature values. Two of the studied compounds, 2,5-dinitrochlorobenzene and 3,5-dinitrobromobenzene, both exhibited mutagenic effects in the Ames test, while both 2,5-dinitrochlorobenzene and 2,6-dichlorobenzene-1,4-diamine were classified as skin sensitizers. The allergenic reactivity of the latter was found to be due to an oxidized transformation product. Risks for the induction of skin allergy and other non-carcinogenic effects from dermal exposure to the individual compounds were found low, even when considering clothing with the highest reported levels. However, the complex mixtures of chemicals often present in garments may still constitute a health risk, especially when considering the many hours of daily exposure. It is important to further study the toxicity of other frequently occurring chemicals as well as the synergistic effects of chemicals that co-occur in clothing.

Neuroprotective and Disease-Modifying Effects of the Triazinetrione ACD856, a Positive Allosteric Modulator of Trk-Receptors for the Treatment of Cognitive Dysfunction in Alzheimer's Disease.

The introduction of anti-amyloid monoclonal antibodies against Alzheimer's disease (AD) is of high importance. However, even though treated patients show very little amyloid pathology, there is only a modest effect on the rate of cognitive decline. Although this effect can possibly increase over time, there is still a need for alternative treatments that will improve cognitive function in patients with AD. Therefore, the purpose of this study was to characterize the triazinetrione ACD856, a novel pan-Trk positive allosteric modulator, in multiple models to address its neuroprotective and potential disease-modifying effects. The pharmacological effect of ACD856 was tested in recombinant cell lines, primary cortical neurons, or animals. We demonstrate that ACD856 enhanced NGF-induced neurite outgrowth, increased the levels of the pre-synaptic protein SNAP25 in PC12 cells, and increased the degree of phosphorylated TrkB in SH-SY5Y cells. In primary cortical neurons, ACD856 led to increased levels of phospho-ERK1/2, showed a neuroprotective effect against amyloid-beta or energy-deprivation-induced neurotoxicity, and increased the levels of brain-derived neurotrophic factor (BDNF). Consequently, administration of ACD856 resulted in a significant increase in BDNF in the brains of 21 months old mice. Furthermore, repeated administration of ACD856 resulted in a sustained anti-depressant effect, which lasted up to seven days, suggesting effects that go beyond merely symptomatic effects. In conclusion, the results confirm ACD856 as a cognitive enhancer, but more importantly, they provide substantial in vitro and in vivo evidence of neuroprotective and long-term effects that contribute to neurotrophic support and increased neuroplasticity. Presumably, the described effects of ACD856 may improve cognition, increase resilience, and promote neurorestorative processes, thereby leading to a healthier brain in patients with AD.

A strategy for early-risk predictions of clinical drug-drug interactions involving the GastroPlusTM DDI module for time-dependent CYP inhibitors.

1. A set of reference compounds for time-dependent inhibition (TDI) of cytochrome P450 with available literature data for kinact and KI was used to predict clinical implications using the GastroPlusTM software. Comparisons were made to in vivo literature interaction data. 2. The predicted AUC ratios (AUC+inhibitor/AUCcontrol) could be compared with the observed ratios from literature for all compounds with detailed information about in vivo administration, pharmacokinetics and in vivo interactions (N = 21). For this dataset, the difference between predicted and observed AUC ratios for interactions with midazolam was within twofold for all compounds except one (telaprevir, for which non-CYP-mediated metabolism likely plays a role after multiple dosing). 3. The sensitivity, specificity and accuracy of the GastroPlusTM predictions using a binary classification as no-to-weak interaction versus moderate-to-strong interaction for all compounds with available in vivo interaction data, were 80%, 82% and 81%, respectively (N = 31). 4. As a result of our evaluations of the DDI module in GastroPlusTM, we have implemented an early TDI risk assessment decision tree for our drug discovery projects involving in vitro screening and early GastroPlusTM predictions. Shifted IC50 values are determined and kinact/KI estimated (by using a regression line established with in house-shifted IC50 values and literature kinact/KI ratios), followed by GastroPlusTM predictions.

Optimizing DMPK Properties: Experiences from a Big Pharma DMPK Department.

BACKGROUND: The disposition of a drug is dependent on interactions between the body and the drug, its molecular properties and the physical and biological barriers presented in the body. In order for a drug to have a desired pharmacological effect it has to have the right properties to be able to reach the target site in sufficient concentration. This review details how drug metabolism and pharmacokinetics (DMPK) and physicochemical deliveries played an important role in data interpretation and compound optimization at AstraZeneca R&D in Södertälje, Sweden. METHODS: A selection of assays central in the evaluation of the DMPK properties of new chemical entities is presented, with guidance and consideration on assay outcome interpretation. Early in projects, solubility, LogD, permeability and metabolic stability were measured to support effective optimization of DMPK properties. Changes made to facilitate high throughput, efficient bioanalysis and the handling of large amounts of samples are described. Already early in drug discovery, we used an integrated approach for the prediction of the fate of drugs in human (early dose to man) based on data obtained from in vitro experiments. The early dose to man was refined with project progression, which triggered more intricate assays and experiments. At later stages, preclinical in vivo pharmacokinetic (PK) data was integrated with pharmacodynamics (PD) to allow predictions of required dose, dose intervals and exposure profile to achieve the desired effect in man. RESULTS AND CONCLUSIONS: A well-defined work flow of DMPK activities from early lead identification up to the selection of a candidate drug was developed. This resulted in a cost effective and efficient optimization of chemical series, and facilitated informed decision making throughout project progress.

The utility of cold-preserved human hepatocytes in studies on cytochrome P450 induction and hepatic drug transport.

Human hepatocytes that had been cold-preserved in SureTran(TM) matrix (Abcellute Ltd, Cardiff, UK) were used for studies on cell viability, cytochrome P450 (CYP) 3A4, 2B6 and 1A2 induction and hepatic drug transporters. It has recently been shown that basal CYP activities are maintained in cold-preserved hepatocytes (Palmgren et al., 2012). After 5 d of cold preservation, the viability was still more than 70%, and after 8 d it was around 60%. In hepatocytes that had been cold-preserved for 3 d, the activity of CYP3A4 was induced around 15-fold upon treatment with 8 µM rifampicin for 72 h. For CYP2B6, the activity was induced 4- to 16-fold in hepatocytes that had been cold-preserved for 3 d and thereafter treated with 1 mM phenobarbital for 72 h. The activity of CYP1A2 was low and close to the limit of detection in non-treated cells that had been cold-preserved for up to 3 d, while the activity increased in cells treated with 0.3-25 µM ß-naphthoflavone for 72 h. CYP3A4, 2B6 and 1A2 mRNA levels were only determined with hepatocytes from one donor and increased upon treatment with the inducers. Hepatic uptakes of estrone-3-sulfate, taurocholate, ipratropium and rosuvastatin were stable in human hepatocytes that had been cold-preserved for up to 2 d. In summary, cold-preserved human hepatocytes demonstrate retained viability and can advantageously be used for in vitro induction studies and for studies of hepatic uptake transporters.

Rat poorly predicts the combined non-absorbed and presystemically metabolized fractions in the human.

1. Intestinal loss, 1 - (Fobs/fH), is the missing fraction of the dose that is unexplained by systemic clearance. Here, we investigated whether intestinal loss in rat is predictive for human, and whether intestinal metabolism explained observed differences between rat and human. 2. For 81 marketed drugs, human and rat intestinal loss values were calculated from the literature and in-house sources. To examine the contribution of intestinal cytochrome P450-mediated metabolism to the high observed intestinal loss in the rat, metabolism was determined in rat and human intestinal microsomes for 15 compounds. 3. Oral bioavailability poorly correlated between rat and human. Twenty-two compounds in the human and 47 compounds in the rat showed an intestinal loss of more than 20%. The intestinal availability for many compounds was higher in human than in rat. Selected compounds, however, were more stable in rat than in human intestinal microsomes. 4. The rat poorly predicts the risk for intestinal loss in human; many compounds in rat had lower bioavailability than anticipated based on the hepatic clearance, but demonstrated little intestinal loss in human. This discrepancy appeared not to be caused by a higher cytochrome P450-mediated intestinal metabolism in the rat.

Thyroxine-thyroid hormone receptor interactions.

Thyroid hormone (TH) actions are mediated by nuclear receptors (TRs alpha and beta) that bind triiodothyronine (T(3), 3,5,3'-triiodo-l-thyronine) with high affinity, and its precursor thyroxine (T(4), 3,5,3',5'-tetraiodo-l-thyronine) with lower affinity. T(4) contains a bulky 5' iodine group absent from T(3). Because T(3) is buried in the core of the ligand binding domain (LBD), we have predicted that TH analogues with 5' substituents should fit poorly into the ligand binding pocket and perhaps behave as antagonists. We therefore examined how T(4) affects TR activity and conformation. We obtained several lines of evidence (ligand dissociation kinetics, migration on hydrophobic interaction columns, and non-denaturing gels) that TR-T(4) complexes adopt a conformation that differs from TR-T(3) complexes in solution. Nonetheless, T(4) behaves as an agonist in vitro (in effects on coregulator and DNA binding) and in cells, when conversion to T(3) does not contribute to agonist activity. We determined x-ray crystal structures of the TRbeta LBD in complex with T(3) and T(4) at 2.5-A and 3.1-A resolution. Comparison of the structures reveals that TRbeta accommodates T(4) through subtle alterations in the loop connecting helices 11 and 12 and amino acid side chains in the pocket, which, together, enlarge a niche that permits helix 12 to pack over the 5' iodine and complete the coactivator binding surface. While T(3) is the major active TH, our results suggest that T(4) could activate nuclear TRs at appropriate concentrations. The ability of TR to adapt to the 5' extension should be considered in TR ligand design.