A Small Domain in the N Terminus of the Regulatory a-Subunit Kv2.3 Modulates Kv2.1 Potassium Channel Gating

Recent work has demonstrated the existence of regulatory K1 channel a-subunits that are electrically silent but capable of forming heterotetramers with other pore-forming subunits to modify their function. We have investigated the molecular determinant of the modulatory effects of Kv2.3, a silent K1 channel a-subunit specific of brain. This subunit induces on Kv2.1 channels a marked deceleration of activation, inactivation, and closing kinetics. We constructed chimeras of the Kv2.1 and Kv2.3 proteins and analyzed the K1 currents resulting from the coexpression of the chimeras with Kv2.1. The data indicate that a region of 59 amino acids in the N terminus, adjacent to the first transmembrane segment, is the major structural element responsible for the regulatory function of Kv2.3. The sequence of this domain of Kv2.3 is highly divergent compared with the same region in the other channels of the Kv2 family. Replacement of the regulatory fragment of Kv2.3 by the equivalent of Kv2.1 leads to loss of modulatory function, whereas gain of modulatory function is observed when the Kv2.3 fragment is transferred to Kv2.1. Thus, this study identifies a N-terminus domain involved in Kv2.1 channel gating and in the modulation of this channel by a regulatory a-subunit

Regulation of oxygen sensing by ion channels

O2 sensing is of critical importance for cell survival and adaptation of living organisms to changing environments or physiological conditions. O2-sensitive ion channels are major effectors of the cellular responses to hypoxia. These channels are preferentially found in excitable neurosecretory cells (glomus cells of the carotid body, cells in the neuroepithelial bodies of the lung, and neonatal adrenal chromaffin cells), which mediate fast cardiorespiratory adjustments to hypoxia. O2- sensitive channels are also expressed in the pulmonary and systemic arterial smooth muscle cells where they participate in the vasomotor responses to low O2 tension (particularly in hypoxic pulmonary vasoconstriction). The mechanisms underlying O2 sensing and how the O2 sensors interact with the ion channels remain unknown. Recent advances in the field give different support to the various current hypotheses. Besides the participation of ion channels in acute O2 sensing, they also contribute to the gene program developed under chronic hypoxia. Gene expression of T-type calcium channels is upregulated by hypoxia through the same hypoxiainducible factor-dependent signaling pathway utilized by the classical O2-regulated genes. Alteration of acute or chronic O2 sensing by ion channels could participate in the pathophysiology of human diseases, such as sudden infant death syndrome or primary pulmonary hypertension

Identification and Functional Characterization of a K1 Channel a- Subunit with Regulatory Properties Specific to Brain

The physiological diversity of K1 channels mainly depends on the expression of several genes encoding different a-subunits. We have cloned a new K1 channel a-subunit (Kv2.3r) that is unable to form functional channels on its own but that has a major regulatory function. Kv2.3r can coassemble selectively with other a-subunits to form functional heteromultimeric K1 channels with kinetic properties that differ from those of the parent channels. Kv2.3r is expressed exclusively in the brain, being concentrated particularly in neocortical neurons. The functional expression of this regulatory a-subunit represents a novel mechanism without precedents in voltage-gated channels, which might contribute to further increase the functional diversity of K1 channels necessary to specify the intrinsic electrical properties of individual neurons

Role of VHL, HIF1A and SDH on the expression of miR-210: Implications for tumoral pseudo-hypoxic fate

The hypoxia-inducible factor 1a (HIF-1a) and its microRNA target, miR-210, are candidate tumor-drivers of metabolic reprogramming in cancer. Neuroendocrine neoplasms such as paragangliomas (PGLs) are particularly appealing for understanding the cancer metabolic adjustments because of their associations with deregulations of metabolic enzymes, such as succinate dehydrogenase (SDH), and the von Hippel Lindau (VHL) gene involved in HIF-1α stabilization. However, the role of miR-210 in the pathogenesis of SDH-related tumors remains an unmet challenge. Herein is described an in vivo genetic analysis of the role of VHL, HIF1A and SDH on miR-210 by using knockout murine models, siRNA gene silencing, and analyses of human tumors. HIF-1a knockout abolished hypoxia-induced miR-210 expression in vivo but did not alter its constitutive expression in paraganglia. Normoxic miR-210 levels substantially increased by complete, but not partial, VHL silencing in paraganglia of knockout VHL-mice and by over-expression of p76del-mutated pVHL. Similarly, VHLmutated PGLs, not those with decreased VHL-gene/mRNA dosage, over-expressed miR-210 and accumulate HIF-1a in most tumor cells. Ablation of SDH activity in SDHD-null cell lines or reduction of the SDHD or SDHB protein levels elicited by siRNA-induced gene silencing did not induce miR-210 whereas the presence of SDH mutations in PGLs and tumor-derived cell lines was associated with mild increase of miR-210 and the presence of a heterogeneous, HIF-1a-positive and HIF-1a-negative, tumor cell population. Thus, activation of HIF-1a is likely an early event in VHLdefective PGLs directly linked to VHL mutations, but it is a late event favored but not directly triggered by SDHx mutations. This combined analysis provides insights into the mechanisms of HIF-1a/miR-210 regulation in normal and tumor tissues potentially useful for understanding the pathogenesis of cancer and other diseases sharing similar underpinnings.Instituto de Salud Carlos III FIS PI11/929Red Temática de Investigación Cooperativa en Cáncer RD12/0036/0015 Instituto de Salud Carlos III (ISCIII)Ministerio de Economía y Competitividad y Fondo Europeo de Desarrollo RegionalFondo Europeo de Desarrollo Regional (FEDER) (CIBERONC

On The Importance Of Remote Sensing Data To Validate A Distributed Dynamic Vegetation Model Applied To A Semi-Arid Basin

Efforts to better understand the components of catchments’ water balance have traditionally been one of the objectives of the hydrological community. Very few hydrological models incorporate vegetation development as state variable. This is beginning to change with the recognition by the hydrological community that biological processes play a key role in catchment’s water balance. In addition, some studies confirm that vegetation density controls most of hydrological processes in semi-arid regions. However, the most of the dynamic vegetation models are too complex to be coupled with hydrological models and they incorporate variables and inputs which are difficult to be estimated across space and through time. For this reason, we have focused on a parsimonious and robust dynamic vegetation model based on the Light Use Efficiency index (LUE), to be coupled with a hydrological model in a semi-arid basin (La Hunde, East of Spain) predominantly covered by Aleppo pine (Pinus halepensis). This model needs to be implemented, i.e. calibrated and validated. Satellite-based remote sensing data are the main source of information employed for this task. In this work, vegetation-related satellite products are analyzed in order to assess their relation with vegetation state at catchment scale. NDVI shows a strong dependence on soil moisture and leaf water content, explainable by the impact of water-stress on chlorophyll content in Aleppo Pine leaves. The EVI proves to be strongly related to biomass dynamics and to LAI in particular

KSHV G-protein coupled receptor vGPCR oncogenic signaling upregulation of Cyclooxygenase-2 expression mediates angiogenesis and tumorigenesis in Kaposi's sarcoma

Kaposi's sarcoma-associated herpesvirus (KSHV) vGPCR is a constitutively active G protein-coupled receptor that subverts proliferative and inflammatory signaling pathways to induce cell transformation in Kaposi's sarcoma. Cyclooxygenase-2 (COX-2) is an inflammatory mediator that plays a key regulatory role in the activation of tumor angiogenesis. Hereby we demonstrate, using two different transformed mouse models, and tumorigenic full KSHV genome-bearing cells, including KSHV-Bac16 based mutant system with a vGPCR deletion, that vGPCR upregulates COX-2 expression and activity, signaling through selective MAPK cascades. We show that vGPCR expression triggers signaling pathways that upregulate COX-2 levels due to a dual effect upon both its gene promoter region and, in mature mRNA, the 3'UTR region that control mRNA stability. Both events are mediated by signaling through ERK1/2 MAPK pathway. Inhibition of COX-2 in vGPCR-transformed cells impairs vGPCRdriven angiogenesis and treatment with the COX-2-selective inhibitory drug Celecoxib produces a significant decrease in tumor growth, pointing to COX-2 activity as critical for vGPCR oncogenicity in vivo and indicating that COX-2-mediated angiogenesis could play a role in KS tumorigenesis. These results, along with the overexpression of COX-2 in KS lesions, define COX-2 as a potential target for the prevention and treatment of KSHV-oncogenesis.Fil: Medina, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: D´Agostino, Agata. University Of Miami Miller School Of Medicine; Estados UnidosFil: Ma, Qi. University Of Miami Miller School Of Medicine; Estados UnidosFil: Eroles, Pilar. University Of Miami Miller School Of Medicine; Estados UnidosFil: Cavallin, Lucas. University Of Miami Miller School Of Medicine; Estados UnidosFil: Chiozzini, Chiara. Miller School Of Medicine; Estados UnidosFil: Sapochnik, Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Cymeryng, Cora Betriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Hyjek, Elizabeth. University of Chicago; Estados UnidosFil: Cesarman, Ethel. Cornell University; Estados UnidosFil: Naipauer, Julian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Mesri, Enrique Alfredo. University Of Miami Miller School Of Medicine; Estados UnidosFil: Coso, Omar Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Hospital Trusts productivity in the English NHS : Uncovering possible drivers of productivity variations

Background: Health care systems in OECD countries are increasingly facing economic challenges and funding pressures. These normally demand interventions (political, financial and organisational) aimed at improving the efficiency of the health system as a whole and its single components. In 2009, the English NHS Chief Executive, Sir David Nicholson, warned that a potential funding gap of £20 billion should be met by extensive efficiency savings by March 2015. Our study investigates possible drivers of differential Trust performance (productivity) for the financial years 2010/11-2012/13. Methods: Following accounting practice, we define Productivity as the ratio of Outputs over Inputs. We analyse variation in both Total Factor and Labour Productivity using ordinary least squares regressions. We explicitly included in our analysis factors of differential performance highlighted in the Nicholson challenge as the sources were the efficiency savings should come from. Explanatory variables include efficiency in resource use measures, Trust and patient characteristics, and quality of care. Results: We find that larger Trusts and Foundation Trusts are associated with lower productivity, as are those treating a greater proportion of both older and/or younger patients. Surprisingly treating more patients in their last year of life is associated with higher Labour Productivity

Serum CD26 is related to histopathological polyp traits and behaves as a marker for colorectal cancer and advanced adenomas

<p>Abstract</p> <p>Background</p> <p>Serum CD26 (sCD26) levels were previously found diminished in colorectal cancer (CRC) patients compared to healthy donors, suggesting its potential utility for early diagnosis. Therefore we aimed to estimate the utility of the sCD26 as a biomarker for CRC and advanced adenomas in a high-risk group of patients. The relationship of this molecule with polyp characteristics was also addressed.</p> <p>Methods</p> <p>sCD26 levels were measured by ELISA in 299 symptomatic and asymptomatic patients who had undergone a colonoscopy. Patients were diagnosed as having no colorectal pathology, non-inflammatory or inflammatory bowel disease, polyps (hyperplastic, non-advanced and advanced adenomas) or CRC.</p> <p>Results</p> <p>At a 460 ng/mL cut-off, the sCD26 has a sensitivity and specificity of 81.8% (95% CI, 64.5-93.0%) and 72.3% (95% CI, 65.0-77.2%) for CRC regarding no or benign colorectal pathology. Clinicopathological analysis of polyps showed a relationship between the sCD26 and the grade of dysplasia and the presence of advanced adenomas. Hence, a 58.0% (95% CI, 46.5-68.9%) sensitivity detecting CRC and advanced adenomas was obtained, with a specificity of 75.5% (95% CI, 68.5-81.0%).</p> <p>Conclusions</p> <p>Our preliminary results show that measurement of the sCD26 is a non-invasive and reasonably sensitive assay, which could be combined with others such as the faecal occult blood test for the early diagnosis and screening of CRC and advanced adenomas. Additional comparative studies in average-risk populations are necessary.</p

Profiling of Flavonol Derivatives for the Development of Antitrypanosomatidic Drugs

Flavonoids represent a potential source of new antitrypanosomatidic leads. Starting from a library of natural products, we combined target-based screening on pteridine reductase 1 with phenotypic screening on Trypanosoma brucei for hit identification. Flavonols were identified as hits, and a library of 16 derivatives was synthesized. Twelve compounds showed EC50 values against T. brucei below 10 \u3bcM. Four X-ray crystal structures and docking studies explained the observed structure-activity relationships. Compound 2 (3,6-dihydroxy-2-(3-hydroxyphenyl)-4H-chromen-4-one) was selected for pharmacokinetic studies. Encapsulation of compound 2 in PLGA nanoparticles or cyclodextrins resulted in lower in vitro toxicity when compared to the free compound. Combination studies with methotrexate revealed that compound 13 (3-hydroxy-6-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one) has the highest synergistic effect at concentration of 1.3 \u3bcM, 11.7-fold dose reduction index and no toxicity toward host cells. Our results provide the basis for further chemical modifications aimed at identifying novel antitrypanosomatidic agents showing higher potency toward PTR1 and increased metabolic stability

Gene expression profiling in whole blood of patients with coronary artery disease

Owing to the dynamic nature of the transcriptome, gene expression profiling is a promising tool for discovery of disease-related genes and biological pathways. In the present study, we examined gene expression in whole blood of 12 patients with CAD (coronary artery disease) and 12 healthy control subjects. Furthermore, ten patients with CAD underwent whole-blood gene expression analysis before and after the completion of a cardiac rehabilitation programme following surgical coronary revascularization. mRNA and miRNA (microRNA) were isolated for expression profiling. Gene expression analysis identified 365 differentially expressed genes in patients with CAD compared with healthy controls (175 up- and 190 down-regulated in CAD), and 645 in CAD rehabilitation patients (196 up- and 449 down-regulated post-rehabilitation). Biological pathway analysis identified a number of canonical pathways, including oxidative phosphorylation and mitochondrial function, as being significantly and consistently modulated across the groups. Analysis of miRNA expression revealed a number of differentially expressed miRNAs, including hsa-miR-140-3p (control compared with CAD, P=0.017), hsa-miR-182 (control compared with CAD, P=0.093), hsa-miR-92a and hsa-miR-92b (post- compared with pre-exercise, P<0.01). Global analysis of predicted miRNA targets found significantly reduced expression of genes with target regions compared with those without: hsa-miR-140-3p (P=0.002), hsa-miR-182 (P=0.001), hsa-miR-92a and hsa-miR-92b (P=2.2×10−16). In conclusion, using whole blood as a ‘surrogate tissue’ in patients with CAD, we have identified differentially expressed miRNAs, differentially regulated genes and modulated pathways which warrant further investigation in the setting of cardiovascular function. This approach may represent a novel non-invasive strategy to unravel potentially modifiable pathways and possible therapeutic targets in cardiovascular disease