The Dirac Equation in the Kerr-de Sitter Metric

We consider a Fermion in the presence of a rotating BH immersed in a universe with a positive cosmological constant. After presenting a rigorous classification of the number and type of the horizons, we adopt the Carter tetrad to separate the aforementioned equation into radial and angular equations. We show how the Chandrasekhar ansatz leads to the construction of a symmetry operator that in the limit of a vanishing cosmological constant reproduces the square root of the squared total angular momentum operator for a Dirac particle in the Kerr metric. Furthermore, we prove that the the spectrum of the angular operator is discrete and consists of simple eigenvalues, and by means of the functional Bethe ansatz method we also derive a set of necessary and sufficient conditions for the angular operator to have polynomial solutions. Finally, we show that there exist no bound states for the Dirac equation in the non-extreme case.     

Antioxidant mechanism of grape procyanidins in muscle tissues: Redox interactions with endogenous ascorbic acid and α-tocopherol

The present study investigates the antioxidant mechanism of grape procyanidins and, in particular, their aptitude to establish redox interactions with two important components of the endogenous antioxidant system of muscle tissues, α-tocopherol (α-TOH) and ascorbic acid (AA). To this end, the progress of lipid oxidation was monitored in fish muscle supplemented with grape procyanidins at the concentrations usually employed in antioxidant food applications, and then related to the redox stability of the endogenous α-TOH and AA. In addition to the lipid oxidation protective effect, the incorporation of procyanidins also provided an improvement of the redox stability of the endogenous components in a straight procyanidinic concentration-dependent manner. Results showed the capacity of procyanidins to repair oxidised α-TOH at medium-long term, and to delay the AA depletion. Therefore, such cooperative redox interaction of exogenous procyanidins adequately complements the natural α-TOH regenerative system supplied by AA that is efficient at the early post mortem stages.     

Crossing Paths in Human Renal Cell Carcinoma (hRCC)

Historically, cell-signaling pathways have been studied as the compilation of isolated elements into a unique cascade that transmits extracellular stimuli to the tumor cell nucleus. Today, growing evidence supports the fact that intracellular drivers of tumor progression do not flow in a single linear pathway, but disseminate into multiple intracellular pathways. An improved understanding of the complexity of cancer depends on the elucidation of the underlying regulatory networks at the cellular and intercellular levels and in their temporal dimension. The high complexity of the intracellular cascades causes the complete inhibition of the growth of one tumor cell to be very unlikely, except in cases in which the so-called “oncogene addiction” is known to be a clear trigger for tumor catastrophe, such as in the case of gastrointestinal stromal tumors or chronic myeloid leukemia. In other words, the separation and isolation of the driver from the passengers is required to improve accuracy in cancer treatment. This review will summarize the signaling pathway crossroads that govern renal cell carcinoma proliferation and the emerging understanding of how these pathways facilitate tumor escape. We outline the available evidence supporting the putative links between different signaling pathways and how they may influence tumor proliferation, differentiation, apoptosis, angiogenesis, metabolism and invasiveness. The conclusion is that tumor cells may generate their own crossroads/crosstalk among signaling pathways, thereby reducing their dependence on stimulation of their physiologic pathways.     

Assessment of the bioavailability of toxic and non-toxic arsenic species in seafood samples

Bioavailability of total arsenic, toxic (arsenite, As(III); and arsenate, As(V)), and non-toxic (monomethylarsonic acid, MA; dimethylarsonic acid, DMA; arsenobetaine, AB; and arsenocholine, AC) arsenic species has been assessed in different raw seafood samples (white fish, cold water fish and molluscs) by using an in vitro model that combines simulated gastric and intestinal digestion/dialysis methods. Correlations between arsenic species bioavailability and seafood nutrient contents (fat and protein) have also been established. Total arsenic content in seafood samples, and dialyzable and non-dialyzable fractions, were analyzed by inductively coupled plasma – mass spectrometry (ICP–MS) after a microwave-assisted acid digestion treatment. The determination of the different arsenic species concentrations in the samples (after an optimised matrix solid phase dispersion (MSPD) approach) and in the dialyzable fraction was done by high performance liquid chromatography (HPLC) coupled to ICP-MS as a selective detector. Accuracy of the procedure (total arsenic determination) was assessed by analyzing DORM-2 and BCR-627 certified reference materials. The accuracy of the in vitro procedure was established through a mass-balance study. After statistical evaluation (95% confidence interval), good accuracy of the whole in vitro process, for total arsenic and for arsenic speciation, was observed. High dialyzability percentages for total arsenic and for arsenic species were found (i.e. from 84.6 ± 1.7% to 106 ± 2.6%). Bioavailability of arsenic exhibits a negative correlation with the fat content of the seafood. However, no correlation was observed between the bioavailable fraction of total arsenic and arsenic species and the protein content of the seafood studied.     

The effects of run‐of‐river dam spill on Columbia River microplankton

Dams, increasingly common in riverine systems worldwide, are particularly prevalent on the Columbia River (CR) in the United States. Hydroelectric projects, including both storage and run‐of‐river (i.e., minimal storage) structures, on the mainstem CR highly manage water flow, often by releasing water over (rather than through) dams as “spill.” To test the effects of run‐of‐river dam spill on microplankton abundance and composition, we sampled above and below two dams in the lower CR before and during spill conditions in spring 2016 and during and after spill conditions in late summer 2007. We tested the effects of location (i.e., above vs. below dams), spill condition (i.e., before, during, and after spill), and their interaction on microplankton abundance. Generally, diatoms were most abundant during springtime, whereas cyanobacteria were most abundant in late summer. Most taxa were not significantly different in abundance above and below dams, regardless of spill status; although cyanobacteria abundance was marginally higher below dams in summer 2007 (p = .04). Abundances of all taxa were significantly different between pre‐spill and spill periods in spring 2016, whereas only diatom and flagellate abundances were significantly different between spill and post‐spill periods in summer 2007. We conclude that spill conditions may influence microplankton abundance, but are not likely to affect microplankton communities on either side of run‐of‐river dams on the CR. This is important information for dam managers concerned about ecosystem impacts of spill.     

Effect of Methionine Sulfoxide on the Synthesis and Purification of Aggregation-Prone Peptides

A two-step synthesis for methionine-containing hydrophobic and/or aggregation-prone peptides is presented that takes advantage of the reversibility of methionine oxidation. The use of polar methionine sulfoxide as a building block in solid-phase peptide synthesis improves the synthesis quality and yields the crude peptide, with significantly improved solubility compared to the reduced species. This facilitates the otherwise often laborious peptide purification by high-performance liquid chromatography. The subsequent reduction proceeds quantitatively. This approach has been optimised with the methionine-rich Tar-DNA-binding protein 43 (307–347), but is also more generally applicable, as demonstrated by the syntheses of human calcitonin and two aggregation-prone peptides from the human prion protein.