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71.
George Valiakos Antonia Touloudi Labrini V. Athanasiou Alexios Giannakopoulos Christos Iacovakis Periklis Birtsas Vassiliki Spyrou Zisis Dalabiras Liljana Petrovska Charalambos Billinis 《European Journal of Wildlife Research》2012,58(4):749-753
A major number of West Nile virus (WNV) infections in humans occurred in 2010 in northern Greece, with 262 laboratory confirmed cases. In 2011, fewer cases were reported, but the pattern was more dispersed throughout the Greek mainland. Isolated strains were similar to lineage 2 strains detected in previous years in Austria and Hungary from birds of prey. We conducted a serological surveillance study on hunter-harvested wild birds, to determine possible exposure of avian species during the current outbreak. Serum samples from a total of 113 Eurasian magpies and 85 turtle doves (abundant resident and migratory avian species, respectively, with potential roles in WNV epidemiology) were tested. These birds were hunter-harvested during 2011 from various prefectures both affected and not affected by the WNV outbreak in Greece. Sera were tested for the presence of WNV IgG antibodies by indirect immunofluorescence assay (IFA). Verification of positive results by a micro-virus neutralization test (VNT) was also performed. A total of 23 out of 113 (20.4%) Eurasian magpies and 6/85 (7.1%) turtle doves were found positive. Results showed association of human cases with wild birds’ exposure to the virus; no avian sera were found positive in prefectures not affected by the WNV outbreak. In contrast, positive avian sera were found in every prefecture that human WNV cases occurred in 2011. High seroprevalence in Eurasian magpies suggests high activity of WNV in the areas. Findings of past exposure of migratory birds like turtle doves to WNV upon their arrival in resting areas in Greece suggest various avian species with similar migration traits as target species for viral isolation studies, as they can be considered candidates for the introduction of WNV lineage 2 in Greece from Central Europe. 相似文献
72.
Stewart R Song L Carter SM Sigalas C Zaccai NR Kanamarlapudi V Bhat MB Takeshima H Sitsapesan R 《The Journal of membrane biology》2008,222(2):65-77
Ryanodine receptor 2 (RyR2) cDNA has been available for more than 15 years; however, due to the complex nature of ligand gating
in this channel, many aspects of recombinant RyR2 function have been unresearched. We established a stable, inducible HEK
293 cell line expressing full-length rabbit RyR2 cDNA and assessed the single-channel properties of the recombinant RyR2,
with particular reference to ligand regulation with Ca2+ as the permeant ion. We found that the single-channel conductances of recombinant RyR2 and RyR2 isolated from cardiac muscle
are essentially identical, as is irreversible modification by ryanodine. Although it is known that RyR2 expressed in HEK 293
cells is not associated with FKBP12.6, we demonstrate that these channels do not exhibit any discernable disorganized gating
characteristics or subconductance states. We also show that the gating of recombinant RyR2 is indistinguishable from that
of channels isolated from cardiac muscle when activated by cytosolic Ca2+, caffeine or suramin. The mechanisms underlying ATP activation are also similar; however, the experiments highlighted a novel
effect of ATP at physiologically relevant concentrations of 5–10 mM. With Ca2+ as permeant ion, 5–10 mM ATP consistently inactivated recombinant channels (15/16 experiments). Such inactivation was rarely
observed with native RyR2 isolated from cardiac muscle (1 in 16 experiments). However, if the channels were purified, inactivation
by ATP was then revealed in all experiments. This action of ATP may be relevant for inactivation of sarcoplasmic reticulum
Ca2+ release during cardiac excitation–contraction coupling or may represent unnatural behavior that is revealed when RyR2 is
purified or expressed in noncardiac systems.
Richard Stewart and Lele Song—contributed equally to this work. 相似文献
73.
Berret B Darlot C Jean F Pozzo T Papaxanthis C Gauthier JP 《PLoS computational biology》2008,4(10):e1000194
An important question in the literature focusing on motor control is to determine which laws drive biological limb movements. This question has prompted numerous investigations analyzing arm movements in both humans and monkeys. Many theories assume that among all possible movements the one actually performed satisfies an optimality criterion. In the framework of optimal control theory, a first approach is to choose a cost function and test whether the proposed model fits with experimental data. A second approach (generally considered as the more difficult) is to infer the cost function from behavioral data. The cost proposed here includes a term called the absolute work of forces, reflecting the mechanical energy expenditure. Contrary to most investigations studying optimality principles of arm movements, this model has the particularity of using a cost function that is not smooth. First, a mathematical theory related to both direct and inverse optimal control approaches is presented. The first theoretical result is the Inactivation Principle, according to which minimizing a term similar to the absolute work implies simultaneous inactivation of agonistic and antagonistic muscles acting on a single joint, near the time of peak velocity. The second theoretical result is that, conversely, the presence of non-smoothness in the cost function is a necessary condition for the existence of such inactivation. Second, during an experimental study, participants were asked to perform fast vertical arm movements with one, two, and three degrees of freedom. Observed trajectories, velocity profiles, and final postures were accurately simulated by the model. In accordance, electromyographic signals showed brief simultaneous inactivation of opposing muscles during movements. Thus, assuming that human movements are optimal with respect to a certain integral cost, the minimization of an absolute-work-like cost is supported by experimental observations. Such types of optimality criteria may be applied to a large range of biological movements. 相似文献
74.
Arianna Filntisi Charalambos Fotakis Pantelis Asvestas George K. Matsopoulos Panagiotis Zoumpoulakis Dionisis Cavouras 《Metabolomics : Official journal of the Metabolomic Society》2017,13(12):146
Introduction
Metabolite identification in biological samples using Nuclear Magnetic Resonance (NMR) spectra is a challenging task due to the complexity of the biological matrices.Objectives
This paper introduces a new, automated computational scheme for the identification of metabolites in 1D 1H NMR spectra based on the Human Metabolome Database.Methods
The methodological scheme comprises of the sequential application of preprocessing, data reduction, metabolite screening and combination selection.Results
The proposed scheme has been tested on the 1D 1H NMR spectra of: (a) an amino acid mixture, (b) a serum sample spiked with the amino acid mixture, (c) 20 blood serum, (d) 20 human amniotic fluid samples, (e) 160 serum samples from publicly available database. The methodological scheme was compared against widely used software tools, exhibiting good performance in terms of correct assignment of the metabolites.Conclusions
This new robust scheme accomplishes to automatically identify peak resonances in 1H-NMR spectra with high accuracy and less human intervention with a wide range of applications in metabolic profiling.75.
Kotzamanidis C Chatzopoulos D Michailidis C Papaiakovou G Patikas D 《Journal of strength and conditioning research / National Strength & Conditioning Association》2005,19(2):369-375
The purpose of this study was to investigate the effect of a combined heavy-resistance and running-speed training program performed in the same training session on strength, running velocity (RV), and vertical-jump performance (VJ) of soccer players. Thirty-five individuals were divided into 3 groups. The first group (n = 12, COM group) performed a combined resistance and speed training program at the same training session, and the second one (n = 11, STR group) performed the same resistance training without speed training. The third group was the control group (n = 12, CON group). Three jump tests were used for the evaluation of vertical jump performance: squat jump, countermovement jump, and drop jump. The 30-m dash and 1 repetition maximum (1RM) tests were used for running speed and strength evaluation, respectively. After training, both experimental groups significantly improved their 1RM of all tested exercises. Furthermore, the COM group performed significantly better than the STR and the CON groups in the 30-m dash, squat jump, and countermovement jump. It is concluded that the combined resistance and running-speed program provides better results than the conventional resistance training, regarding the power performance of soccer players. 相似文献
76.
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78.
Constantina A. Sarri Maria Markantoni Costas Stamatis Anna Papa Athanasios Tsakris Danai Pervanidou Agoritsa Baka Constantina Politis Charalambos Billinis Christos Hadjichristodoulou Zissis Mamuris MALWEST project 《PloS one》2016,11(11)
WNV is a zoonotic neurotropic flavivirus that has recently emerged globally as a significant cause of viral encephalitis. The last five years, 624 incidents of WNV infection have been reported in Greece. The risk for severe WNV disease increases among immunosuppressed individuals implying thus the contribution of the MHC locus to the control of WNV infection. In order to investigate a possible association of MHC class II genes, especially HLA-DPA1, HLA-DQA1, HLA-DRB1, we examined 105 WNV patients, including 68 cases with neuroinvasive disease and 37 cases with mild clinical phenotype, collected during the period from 2010 to2013, and 100 control individuals selected form the Greek population. Typing was performed for exon 2 for all three genes. DQA1*01:01 was considered to be "protective" against WNV infection (25.4% vs 40.1%, P = 0.004) while DQA1*01:02 was associated with increased susceptibility (48.0% vs 32.1%, P = 0.003). Protection against neuroinvasion was associated with the presence of DRB1*11:02 (4.99% vs 0.0%, P = 0.018). DRB1*16:02 was also absent from the control cohort (P = 0.016). Three additional population control groups were used in order to validate our results. No statistically significant association with the disease was found for HLA-DPA alleles. The results of the present study provide some evidence that MHC class II is involved in the response to WNV infection, outlining infection "susceptibility" and "CNS-high-risk" candidates. Furthermore, three new alleles were identified while the frequency of all alleles in the study was compared with worldwide data. The characterization of the MHC locus could help to estimate the risk for severe WNV cases in a country. 相似文献
79.
Charalambos Sigalas 《Biophysical journal》2009,97(7):1907-1916
We have shown that physiological levels of Ca2+-calmodulin (Ca2+CaM; 50-100 nM) activate cardiac ryanodine receptors (RyR2) incorporated into bilayers and increase the frequency of Ca2+ sparks and waves in cardiac cells. In contrast, it is well known that Ca2+CaM inhibits [3H]ryanodine binding to cardiac sarcoplasmic reticulum. Since the [3H]ryanodine binding technique does not reflect the effects of Ca2+CaM on RyR2 open probability (Po), we have investigated, using the reversible ryanoid, ryanodol, whether Ca2+CaM can directly influence the binding of ryanoids to single RyR2 channels independently of Po. We demonstrate that Ca2+CaM reduces the rate of ryanodol association to RyR2 without affecting the rate of dissociation. We also find that ryanodol-bound channels fluctuate between at least two distinct subconductance states, M1 and M2, in a voltage-dependent manner. Ca2+CaM significantly alters the equilibrium between these two states. The results suggest that Ca2+CaM binding to RyR2 causes a conformation change to regions of the channel that include the ryanoid binding site, thereby leading to a decrease in ryanoid association rate and modulation of gating within the ryanoid/RyR2 bound state. Our data provide a possible explanation for why the effects of Ca2+CaM at the single-channel level are not mirrored by [3H]ryanodine binding studies. 相似文献