Block of Kcnk3 by protons. Evidence that 2-P-domain potassium channel subunits function as homodimers.

KCNK subunits have two pore-forming P domains and four predicted transmembrane segments. To assess the number of subunits in each pore, we studied external proton block of Kcnk3, a subunit prominent in rodent heart and brain. Consistent with a pore-blocking mechanism, inhibition was dependent on voltage, potassium concentration, and a histidine in the first P domain (P1H). Thus, at pH 6.8 with 20 mm potassium half the current passed by P1H channels was blocked (apparently via two sites approximately 10% into the electrical field) whereas channels with an asparagine substitution (P1N) were fully active. Furthermore, pore blockade by barium was sensitive to pH in P1H but not P1N channels. Although linking two Kcnk3 subunits in tandem to produce P1H-P1H and P1N-P1N channels bearing four P domains did not alter these attributes, the mixed tandems P1H-P1N and P1N-P1H were half-blocked at pH approximately 6.4, apparently via a single site. This implicates a dimeric structure for Kcnk3 channels with two (and only two) P1 domains in each pore and argues that P2 domains also contribute to pore formation

Proton block and voltage gating are potassium-dependent in the cardiac leak channel Kcnk3.

Potassium leak conductances were recently revealed to exist as independent molecular entities. Here, the genomic structure, cardiac localization, and biophysical properties of a murine example are considered. Kcnk3 subunits have two pore-forming P domains and unique functional attributes. At steady state, Kcnk3 channels behave like open, potassium-selective, transmembrane holes that are inhibited by physiological levels of proton. With voltage steps, Kcnk3 channels open and close in two phases, one appears to be immediate and one is time-dependent (tau = approximately 5 ms). Both proton block and gating are potassium-sensitive; this produces an anomalous increase in outward flux as external potassium levels rise because of decreased proton block. Single Kcnk3 channels open across the physiological voltage range; hence they are "leak" conductances; however, they open only briefly and rarely even after exposure to agents that activate other potassium channels

Retinal gene therapy with a large MYO7A cDNA using adeno-associated virus.

Usher 1 patients are born profoundly deaf and then develop retinal degeneration. Thus they are readily identified before the onset of retinal degeneration, making gene therapy a viable strategy to prevent their blindness. Here, we have investigated the use of adeno-associated viruses (AAVs) for the delivery of the Usher 1B gene, MYO7A, to retinal cells in cell culture and in Myo7a-null mice. MYO7A cDNA, under control of a smCBA promoter, was packaged in single AAV2 and AAV5 vectors and as two overlapping halves in dual AAV2 vectors. The 7.9-kb smCBA-MYO7A exceeds the capacity of an AAV vector; packaging of such oversized constructs into single AAV vectors may involve fragmentation of the gene. Nevertheless, the AAV2 and AAV5 single vector preparations successfully transduced photoreceptor and retinal pigment epithelium cells, resulting in functional, full-length MYO7A protein and correction of mutant phenotypes, suggesting successful homologous recombination of gene fragments. With discrete, conventional-sized dual AAV2 vectors, full-length MYO7A was detected, but the level of protein expression was variable, and only a minority of cells showed phenotype correction. Our results show that MYO7A therapy with AAV2 or AAV5 single vectors is efficacious; however, the dual AAV2 approach proved to be less effective

Improving the minimum description length inference of phrase-based translation models

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-19390-8_25We study the application of minimum description length (MDL) inference to estimate pattern recognition models for machine translation. MDL is a theoretically-sound approach whose empirical results are however below those of the state-of-the-art pipeline of training heuristics. We identify potential limitations of current MDL procedures and provide a practical approach to overcome them. Empirical results support the soundness of the proposed approach.Work supported by the EU 7th Framework Programme (FP7/2007–2013) under the CasMaCat project (grant agreement no 287576), by Spanish MICINN under grant TIN2012-31723, and by the Generalitat Valenciana under grant ALMPR (Prometeo/2009/014).Gonzalez Rubio, J.; Casacuberta Nolla, F. (2015). Improving the minimum description length inference of phrase-based translation models. En Pattern Recognition and Image Analysis: 7th Iberian Conference, IbPRIA 2015, Santiago de Compostela, Spain, June 17-19, 2015, Proceedings. Springer International Publishing. 219-227. https://doi.org/10.1007/978-3-319-19390-8 25S21922

Role of glucose as a modulator of anabolic and catabolic gene expression in normal and osteoarthritic human chondrocytes

Cartilage matrix homeostasis involves a dynamic balance between numerous signals that modulate chondrocyte functions. This study aimed at elucidating the role of the extracellular glucose concentration in modulating anabolic and catabolic gene expression in normal and osteoarthritic (OA) human chondrocytes and its ability to modify the gene expression responses induced by pro-anabolic stimuli, namely Transforming Growth Factor-β (TGF). For this, we analyzed by real time RT-PCR the expression of articular cartilage matrix-specific and non-specific genes, namely collagen types II and I, respectively. The expression of the matrix metalloproteinases (MMPs)-1 and -13, which plays a major role in cartilage degradation in arthritic conditions, and of their tissue inhibitors (TIMP) was also measured. The results showed that exposure to high glucose (30 mM) increased the mRNA levels of both MMPs in OA chondrocytes, whereas in normal ones only MMP-1 increased. Collagen II mRNA was similarly increased in normal and OA chondrocytes, but the increase lasted longer in the later. Exposure to high glucose for 24 h prevented TGF-induced downregulation of MMP-13 gene expression in normal and OA chondrocytes, while the inhibitory effect of TGF on MMP-1 expression was only partially reduced. Other responses were not significantly modified. In conclusion, exposure of human chondrocytes to high glucose, as occurs in vivo in diabetes mellitus patients and in vitro for the production of engineered cartilage, favors the chondrocyte catabolic program. This may promote articular cartilage degradation, facilitating OA development and/or progression, as well as compromise the quality and consequent in vivo efficacy of tissue engineered cartilage

NUMERICAL-CALCULATIONS OF THE ELECTRICAL EFFECTS INDUCED BY STRUCTURAL IMPERFECTIONS ON MOS CAPACITORS

As the thickness of gate quality SiO2 is reduced, minor structural interface imperfections begin to play an important role in device performance and yield. To isolate the effects of a variety of such interface imperfections on electric field distribution within the SiO2 layer of biased metal oxide semiconductor capacitors, numerical calculations were carried out. The results indicate that strong electric field distortions may be expected for almost any interfacial defect configuration, being highest for metal precipitates. Technological consequences of the findings are also discussed.14161621162

U-dual fluxes and Generalized Geometry

We perform a systematic analysis of generic string flux compactifications, making use of Exceptional Generalized Geometry (EGG) as an organizing principle. In particular, we establish the precise map between fluxes, gaugings of maximal 4d supergravity and EGG, identifying the complete set of gaugings that admit an uplift to 10d heterotic or type IIB supegravity backgrounds. Our results reveal a rich structure, involving new deformations of 10d supergravity backgrounds, such as the RR counterparts of the $\beta$-deformation. These new deformations are expected to provide the natural extension of the $\beta$-deformation to full-fledged F-theory backgrounds. Our analysis also provides some clues on the 10d origin of some of the particularly less understood gaugings of 4d supergravity. Finally, we derive the explicit expression for the effective superpotential in arbitrary N = 1 heterotic or type IIB orientifold compactifications, for all the allowed fluxes.Comment: 58 pages, 6 table

Transcription factor NRF2 protects mice against dietary iron-induced liver injury by preventing hepatocytic cell death

BACKGROUND & AIMS: The liver, being the major site of iron storage, is particularly exposed to the toxic effects of iron. Transcription factor NRF2 is critical for protecting the liver against disease by activating the transcription of genes encoding detoxification/antioxidant enzymes. We aimed to determine if the NRF2 pathway plays a significant role in the protection against hepatic iron overload.METHODS: Wild-type and Nrf2(-/-) mouse primary hepatocytes were incubated with ferric ammonium citrate. Wild-type and Nrf2(-/-) mice were fed standard rodent chow or iron-rich diet for 2weeks, with or without daily injection of the antioxidant mito-TEMPOL.RESULTS: In mouse hepatocytes, iron induced the nuclear translocation of NRF2 and the expression of cytoprotective genes in an NRF2-dependent manner. Moreover, Nrf2(-/-) hepatocytes were highly susceptible to iron-induced cell death. Wild-type and Nrf2(-/-) mice fed iron-rich diet accumulated similar amounts of iron in the liver and were equally able to increase the expression of hepatic hepcidin and ferritin. Nevertheless, in Nrf2-null mice the iron loading resulted in progressive liver injury, ranging from mild confluent necrosis to severe necroinflammatory lesions. Hepatocytic cell death was associated with gross ultrastructural damage to the mitochondria. Notably, liver injury was prevented in iron-fed animals that received mito-TEMPOL.CONCLUSIONS: NRF2 protects the mouse liver against the toxicity of dietary iron overload by preventing hepatocytic cell death. We identify NRF2 as a potential modifier of liver disease in iron overload pathology and show the beneficial effect of the antioxidant mito-TEMPOL in a mouse model of dietary iron-induced liver injury.This work is funded by FEDER Funds through the Operational Competitiveness Programme - COMPETE and by National Funds through FCT - Fundacao para a Ciencia e a Tecnologia under the project FCOMP-01-0124-FEDER-011062 (PTDC/SAU-FCF/101177/2008). TLD is supported by "Programa Ciencia - financiado pelo POPH - QREN - Tipologia 4.2 - Promocao do Emprego Cientifico, comparticipado pelo Fundo Social Europeu e por fundos nacionais do MCTES''

Physiological and enzymatic changes in rice seeds stored at low temperatures

This study aimed to evaluate the effect of low temperatures on the physiological and enzymatic changes of rice seeds. The seeds were packed in airtight chambers and maintained at temperatures of 8 and -50°C for periods of 15, 30 , 45, 60, 75 and 90 days. The same procedure was adopted for the control treatment with the seeds  kept at a temperature of 25°C. The seeds were evaluated regarding germination test; seedling emergency;  emergency speed index; length and dry weight of radicle; and seedling of shoot. The activity of amylase and  total protein content were also evaluated. The temperatures of 8 and -50°C significantly influenced the  physiological quality and the enzyme amylase activity of rice seeds, resulting in higher germination, seedling  emergence and enzyme activity. The temperature is a promising alternative for the maintenance of  physiological quality and enzymatic activity of rice seeds during storage. Key words: Oryza sativa L., enzymatic activity, physiological quality, storage.Abbreviation: ESI, Emergence speed index; PVP, polyvinylpyrrolidone

Acute renal failure in critically ill HIV-infected patients

Acute renal failure (ARF) is common among hospitalized HIV-infected patients [1]. To our knowledge, however, data regarding ARF in HIV-infected patients in the intensive care unit are still lacking