Binding of PFOS to serum albumin and DNA: insight into the molecular toxicity of perfluorochemicals

<p>Abstract</p> <p>Background</p> <p>Health risk from exposure of perfluorochemicals (PFCs) to wildlife and human has been a subject of great interest for understanding their molecular mechanism of toxicity. Although much work has been done, the toxigenicity of PFCs remains largely unknown. In this work, the non-covalent interactions between perfluorooctane sulfonate (PFOS) and serum albumin (SA) and DNA were investigated under normal physiological conditions, aiming to elucidate the toxigenicity of PFCs.</p> <p>Results</p> <p>In equilibrium dialysis assay, the bindings of PFOS to SA correspond to the Langmuir isothermal model with two-step sequence model. The saturation binding number of PFOS was 45 per molecule of SA and 1 per three base-pairs of DNA, respectively. ITC results showed that all the interactions were spontaneous driven by entropy change. Static quenching of the fluorescence of SA was observed when interacting with PFOS, indicating PFOS bound Trp residue of SA. CD spectra of SA and DNA changed obviously in the presence of PFOS. At normal physiological conditions, 1.2 mmol/l PFOS reduces the binding ratio of Vitamin B₂to SA by more than 30%.</p> <p>Conclusion</p> <p>The ion bond, van der Waals force and hydrophobic interaction contributed to PFOS binding to peptide chain of SA and to the groove bases of DNA duplex. The non-covalent interactions of PFOS with SA and DNA alter their secondary conformations, with the physiological function of SA to transport Vitamin B₂being inhibited consequently. This work provides a useful experimental method for further studying the toxigenicity of PFCs.</p

Poly[aqua­(μ2-oxalato)(4-oxidopyri­din­ium)erbium(II)]

The title complex, [Er(C5H5NO)(C2O4)(H2O)]n, is a new erbium polymer based on oxalate and 4-oxidopyridinium ligands. The ErII center is coordinated by six O atoms from three oxalate ligands, one O atom from a 4-oxidopyridinium ligand and one water mol­ecule, and displays a distorted square-anti­prismatic coordination geometry. The oxalate ligands are both chelating and bridging, and link ErII ions, forming Er–oxalate layers in which the attached water and 4-oxidopyridinium units point alternately up and down. A mirror plane passes through the Er atom, one C, the oxide O and two oxalate O atoms. The layers are assembled into a three-dimensional supra­molecular network via inter­molecular hydrogen bonding and π–π stacking inter­actions [centroid–centroid distances of 3.587 (2) Å between parallel pyridinium rings]. Both the water mol­ecule and the 4-oxidopyridinium ligand are disordered over two sites in a 1:1 ratio

Topological surface electronic states in candidate nodal-line semimetal CaAgAs

We investigate systematically the bulk and surface electronic structure of the candidate nodal-line semimetal CaAgAs by angle resolved photoemission spectroscopy and density functional calculations. We observed a metallic, linear, non-$k_z$-dispersive surface band that coincides with the high-binding-energy part of the theoretical topological surface state, proving the topological nontriviality of the system. An overall downshift of the experimental Fermi level points to a rigid-band-like $p$-doping of the samples, due possibly to Ag vacancies in the as-grown crystals.Comment: 6 pages, 5 figure

Species and sex comparisons of karyotype and genome size in two <em>Kurixalus tree</em> frogs (Anura, Rhacophoridae)

Kurixalus is a rhacophorid genus of tree frogs that are similar in morphology but vary in reproductive behavior. We investigated the cytogenetic features and genome size using conventional G-banding, C-banding and silver-staining techniques, fluorescence in situ hybridization (FISH), and flow cytometry in two representatives of Kurixalus (K. eiffingeri Boettger, 1895 and K. idiootocus Kuramoto and Wang, 1987) and compared the data between species and sex. The two Kurixalus species share a diploid chromosome number 2n = 26 and fundamental number FN = 52. Prominent differences between species were noted in the distribution of secondary constriction (SC)/nucleolus organizer region (NOR) and dense heterochromatin. Other interspecies differences including variations in the number of metacentric and submetacentric chromosomes and staining intensity of heterochromatin were also found. The cytogenetic results are consistent with the observed differences in their genome sizes. FISH with telomeric motif (TTAGGG)n for both species detected signals in the terminal regions. Intersex comparisons revealed no differences in terms of cytogenetic features and genome size in the two species. Despite the apparent highly conserved diploid chromosome number, data on the karyotype microstructure characterize the cytogenetic profile of the two Kurixalus species that contribute to clarification of the chromosomal homologies and the rearrangement mechanisms occurring during the karyotype evolution of Kurixalus. No heteromorphic chromosome pair in both species is consistent with the view that homomorphic sex chromosome is common in amphibians

[[alternative]]台灣消費者自備環保購物袋意願之研究：從道德觀點和計畫行為理論

[[abstract]]Following Chan and coworkers’ (2008) research, the current study integrated Hunt and Vitell’s (1986) ethics perspective and Theory of Planned Behavior (TPB) to present a model that explains consumers’ intention to “Bring Your Own Shopping Bags” (BYOB) with grocery shopping. The proposed model is empirically validated in Taiwan. Based on a survey of 601 respondents, the findings suggest that consumers’ deontological evaluation is positively related to their attitude, subjective norm, and perceived behavioral control, while teleological evaluation is positively related to perceived behavioral control only. In addition, the results also indicate that consumers’ attitude and perceived behavioral control has a positive relationship with BYOB intention, while subjective norm does not have a signification relationship with BYOB intention. In sum, this study contributes to the literature by providing insights for applying general ethics and theory of planned behavior to explain consumers’ BYOB behavior. The results also provide policy makers guidelines regarding BYOB. Managerial implications and research limitations are discussed at the end of this paper.[[notice]]補正完

Control of Anticoagulation Therapy in Patients with Atrial Fibrillation Treated with Warfarin:A Study from the Chinese Atrial Fibrillation Registry

Background: Several factors determine the efficacy of warfarin anticoagulation in patients with non-valvular atrial fibrillation (NVAF). This study aimed to use data from the Chinese Atrial Fibrillation Registry study to assess the control of anticoagulation therapy in Chinese patients with NVAF treated with warfarin. Material/Methods: From the Chinese Atrial Fibrillation Registry study the anticoagulant use and dosing, the time in therapeutic range (TTR) of the international normalized ratio (INR), and standard deviation of the observed INR values (SD INR), and their influencing factors were evaluated. Results: The median INR and SD INR were 2.04 (IQR 1.71–2.41) and 0.50 (IQR, 0.35–0.69), respectively. The median TTR was 51.7% (IQR, 30.6–70.1%) and only 25.1% had a TTR ≥70%. Age was ≥70 years (OR, 0.72; 95% CI, 0.55–0.94; P=0.015), bleeding history (OR 0.48; 95% CI, 0.23–0.89; P=0.029), the use of a single drug (OR, 0.62; 95% CI, 0.42–0.92; P=0.016), more than drug (OR, 0.60; 95% CI, 0.41–0.88; P=0.009), and lack of assessment of bleeding risk (OR, 0.72; 95% CI, 0.54–0.97; P=0.033) were associated with TTR &lt;70% (INR 2.0–3.0). Coronary heart disease (CHD) and peripheral artery disease (PAD) (OR, 0.69; 95% CI, 0.52–0.90; P=0.007) and diabetes mellitus (OR, 0.79; 95% CI, 0.62–0.99; P=0.044) were associated with increased variability in INR (SD INR ≥0.5). Conclusions: In Chinese patients with NVAF, warfarin anticoagulation was associated with lower TTR and less stable anticoagulation than in current guidelines, and risk factors for reduced safety and efficacy were identified. </p