Origin of functional diversity among tetrameric voltage-gated channels

The aim of the present work is to relate functional differences of voltage-gated K(+) (K(v)), hyperpolarization-activated cyclic nucleotide-gated (HCN), and cyclic nucleotide gated (CNG) channels to differences in their amino acid sequences. By means of combined bioinformatic sequence analyses and homology modelling, we suggest that: (1) CNG channels are less voltage-dependent than K(v) channels since the charge of their voltage sensor, the S4 helix, is lower than that of K(v) channels and because of the presence of a conserved proline in the S4-S5 linker, which is quite likely to uncouple S4 from S5 and S6. (2) In HCN channels, S4 features a higher net positive charge with respect to K(v) channels and an extensive network of hydrophobic residues, which is quite likely to provide a tight coupling among S4 and the neighboring helices. We suggest insights on the gating of HCN channels and the reasons why they open with membrane hyperpolarization and with a significantly longer time constant with respect to other channels.     

A two years study results in the use of artificial neural networks to forecast Plasmopara viticola infection in viticulture

This paper describes the further results of the study that has been described in session 5 of the 58th International Symposium on Crop Protection (Ghent 2006). Since then our attention has been focused on verifying the previous communication results working on a two years basis data set belonging to a specific farm. The choice of using data from a single farm derives from the considerations that have been explained in the previous study in which it was clear that an efficient forecasting Artificial Neural Network (ANN) model can be created only in restricted (or at least comparable) pedoclimatic areas. On the basis of the matured experience, at the moment we have realized an ANN which, being trained on 2005 year data, elaborating the following year data is capable of correctly predicting the real Plasmopara viticola (Berk. et Curt.) Berl. et De Toni outbreak, never giving false negative signals (no alarm in presence of infection on the field) and, finally, giving few other alarms which are totally comparable with the ones given by the most common statistical instrument used in this field trials. We confirm the advantages of this approach in terms of: (a) Management and optimization improvement of agricultural activities. (b) Reduction of plant protection products use. (c) Quality improvement of the final product for a real lowering of plant protection products use. (d) Reduction of environmental impact. (e) A more efficient management of the climate changes.     

Tor1, Sch9 and PKA downregulation in quiescence rely on Mtl1 to preserve mitochondrial integrity and cell survival

Here we show that Mtl1, member of the cell wall integrity pathway of Saccharomyces cerevisiae, plays a positive role in chronological life span (CLS). The absence of Mtl1 shortens CLS and causes impairment in the mitochondrial function. This is reflected in a descent in oxygen consumption during the postdiauxic state, an increase in the uncoupled respiration and mitochondrial membrane potential and also a descent in aconitase activity. We demonstrate that all these effects are a consequence of signalling defects suppressed by TOR1 (target of rapamycin) and SCH9 deletion and less efficiently by Protein kinase A (PKA) inactivation. Mtl1 also plays a role in the regulation of both Bcy1 stability and phosphorylation, mainly in response to glucose depletion. In postdiauxic phase and in conditions of glucose depletion, Mtl1 negatively regulates TOR1 function leading to Sch9 inactivation and Bcy1 phosphorylation converging in PKA inhibition. Slt2/Mpk1 kinase partially contributes to Bcy1 phosphorylation, although additional targets are not excluded. Mtl1 links mitochondrial dysfunction with TOR and PKA pathways in quiescence, glucose being the main signalling molecule.     

Functional Effect of Pim1 Depends upon Intracellular Localization in Human Cardiac Progenitor Cells

Human cardiac progenitor cells (hCPC) improve heart function after autologous transfer in heart failure patients. Regenerative potential of hCPCs is severely limited with age, requiring genetic modification to enhance therapeutic potential. A legacy of work from our laboratory with Pim1 kinase reveals effects on proliferation, survival, metabolism, and rejuvenation of hCPCs in vitro and in vivo. We demonstrate that subcellular targeting of Pim1 bolsters the distinct cardioprotective effects of this kinase in hCPCs to increase proliferation and survival, and antagonize cellular senescence. Adult hCPCs isolated from patients undergoing left ventricular assist device implantation were engineered to overexpress Pim1 throughout the cell (PimWT) or targeted to either mitochondrial (Mito-Pim1) or nuclear (Nuc-Pim1) compartments. Nuc-Pim1 enhances stem cell youthfulness associated with decreased senescence-associated β-galactosidase activity, preserved telomere length, reduced expression of p16 and p53, and up-regulation of nucleostemin relative to PimWT hCPCs. Alternately, Mito-Pim1 enhances survival by increasing expression of Bcl-2 and Bcl-X_L and decreasing cell death after H₂O₂ treatment, thereby preserving mitochondrial integrity superior to PimWT. Mito-Pim1 increases the proliferation rate by up-regulation of cell cycle modulators Cyclin D, CDK4, and phospho-Rb. Optimal stem cell traits such as proliferation, survival, and increased youthful properties of aged hCPCs are enhanced after targeted Pim1 localization to mitochondrial or nuclear compartments. Targeted Pim1 overexpression in hCPCs allows for selection of the desired phenotypic properties to overcome patient variability and improve specific stem cell characteristics.     

The Protein Acetyltransferase PatZ from Escherichia coli Is Regulated by Autoacetylation-induced Oligomerization

Lysine acetylation is an important post-translational modification in the metabolic regulation of both prokaryotes and eukaryotes. In Escherichia coli, PatZ (formerly YfiQ) is the only known acetyltransferase protein and is responsible for acetyl-CoA synthetase acetylation. In this study, we demonstrated PatZ-positive cooperativity in response to acetyl-CoA and the regulation of acetyl-CoA synthetase activity by the acetylation level. Furthermore, functional analysis of an E809A mutant showed that the conserved glutamate residue is not relevant for the PatZ catalytic mechanism. Biophysical studies demonstrated that PatZ is a stable tetramer in solution and is transformed to its octameric form by autoacetylation. Moreover, this modification is reversed by the sirtuin CobB. Finally, an in silico PatZ tetramerization model based on hydrophobic and electrostatic interactions is proposed and validated by three-dimensional hydrodynamic analysis. These data reveal, for the first time, the structural regulation of an acetyltransferase by autoacetylation in a prokaryotic organism.     

Are atopy and eosinophilic bronchial inflammation associated with relapsing forms of chronic rhinosinusitis with nasal polyps?

Background

The aetiopathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) is still unknown. The role of atopy and the concept of united airways in such patients are still a matter of debate. In this pilot study we aimed at evaluating the degree of eosinophilic inflammation and the frequency of atopy in a cohort of CRSwNP patients candidate for Functional Endoscopic Sinus Surgery (FESS) and assessing the association between these factors and relapsing forms of CRSwNP.

Methods

30 patients (18 men, 12 women) with CRSwNP eligible for FESS were evaluated before and after surgery. Preoperative investigation included: history of previous relapse after FESS, clinical and laboratory allergologic assessment, spirometry, methacholine challenge, blood eosinophilia and determination of the fraction of nitric oxide in exhaled air (FeNO). Nasal fibroendoscopy, spirometry and FeNO determination were also assessed prospectively at 3 and 27 months post-FESS.

Results

18/30 subjects were atopic, 6/18 (33 %) were monosensitized, 16/30 (53 %) were asthmatics and 10/30 (33 %) had non steroidalantinflammatory drugs (NSAIDs) hypersensitivity. Twenty-one patients (70 %) were classified as relapsers, 15/18 (83 %) among atopics, 6/12 (50 %) among non atopics (p = 0.05). Among patients with NSAIDs hypersensitivity, 9/10 (90 %) were relapsers. The median IgE concentration was 161.5 UI/mL in relapsers and 79 UI/mL in non-relapsers (ns). The mean FeNO decreased after FESS (43.1–26.6 ppb) in 84 % of patients, but this effect disappeared over time (FeNO = 37.7 ppb at 27 months). Higher levels of FeNO pre-FESS were detected in atopics, and in particular in relapsing ones (median 51.1 ppb vs 22.1, ns). Higher levels of FeNO pre-FESS were detected in asthmatic patients, especially in those who relapsed (median: 67 vs 64.85 ppb in non-relapsed patients, ns). The Tiffeneau Index (FEV1/FVC) was significantly lower in asthmatic relapsers than in non relapsers asthmatics (94.7 ± 11.1 versus 105 ± 5.9—p = 0.04). Patients with asthma and atopy had a major risk of relapse (p = 0.05).

Conclusion

In our pilot study, atopy, severe asthma, bronchial inflammation, NSAIDs hypersensitivity and high level of total IgE are possible useful prognostic factors for the proneness to relapse after FESS. The role of allergy in CRSwNP pathogenesis should consequently be given deeper consideration. Allergen specific immunotherapy, combined with anti-IgE therapy, may have an immunomodulatory effect preventing polyps relapse and need to be investigated.

Electronic supplementary material

The online version of this article (doi:10.1186/s12948-015-0026-8) contains supplementary material, which is available to authorized users.     

Exercise intensity and pacing strategy of a 5-km indoor race walk during a World Record attempt: a case study

The aim of this case study was to describe the physiological and regulatory processes, by means of heart rate (HR) monitoring and pacing strategy, in a top-level race walker (age: 32 years; height: 1.76 m; body mass: 62 kg; training volume: 130-150 km·wk) who was focused on the attainment of the 5-km indoor race walk (RW) World Record. The HRmean was 185 ± 14.9 b·min, with an HRmean/HRmax ratio of 0.96. Almost the whole race (91.8%) was performed to an intensity ≥90% of the HRmax; lower intensity work was negligible (8.1%). The race profile was a reverse J-shaped pacing curve; in fact, the athlete completed the first 1,000 m in the fastest time, slowing during the middle 3,000 m, and increasing the speed during the final 1,000 m of the race. Despite the attempt failed (the athlete performed only the 2009 World leading performance, 18 minutes 23 seconds 47 tenths), these data suggest that a more linear strain distribution for the entire performance would be optimal instead of a fast-start strategy, which leads to a drastic decrement of the walking velocity. Moreover, this study supports the use of HR monitoring combined with the regulation of the effort to understand the physiological and regulatory processes during an indoor RW event.