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111.
Mounir?ChennaouiEmail author Catherine?Drogou Fabien?Sauvet Danielle?Gomez-Merino Denis?E.?Scofield Bradley?C.?Nindl 《European cytokine network》2014,25(3):52-57
Acute sleep deprivation in humans has been found to increase inflammatory markers and signaling pathways in the periphery through a possible Toll-like receptor 4 (TLR-4). In addition, short duration sleep has been associated with low circulating total Insulin-like Growth Factor-I (IGF-I) concentrations.We aimed to determine whether a total sleep deprivation (TSD) protocol with recovery altered whole-blood gene expression of the proinflammatory cytokines TNF-α and IL-6, as well as TLR-4 expression, and to examine the relationship with circulating concentrations of the IGF-I system. Twelve healthy men participated in a five-day TSD (two control nights followed by one night of sleep deprivation and one night of recovery). Blood was sampled at 0800, before and after sleep deprivation (D2 and D4), and after recovery (D5). It is shown that 25h of sleep deprivation (D4) induced significant increases in mRNA levels of TNF-α and its soluble receptor R1 (P<0.01 respectively), as well as TLR-4 (P<0.05), while IL-6 mRNA levels remained unchanged. Circulating concentrations of free IGF-I were decreased at D4 (P<0.001). One night of recovery was sufficient to restore basal expression levels for TNF-α, sTNF-R1, TLR-4 and circulating IGF-I. Changes in TLR-4 mRNA levels during the protocol correlated positively with those of TNF-α and sTNF-R1 (r = 0.393 and r = 0.490 respectively), and negatively with circulating free IGF-I (r = ?0.494). In conclusion, 25h of sleep deprivation in healthy subjects is sufficient to induce transient and reversible genomic expression of the pro-inflammatory cytokine TNF-α and its R1 receptor, and its mediator TLR-4, with a possible link to IGF-I axis inhibition. 相似文献
112.
Andraž Polak Daniel Bonhenry François Dehez Peter Kramar Damijan Miklavčič Mounir Tarek 《The Journal of membrane biology》2013,246(11):843-850
Electroporation relates to the cascade of events that follows the application of high electric fields and that leads to cell membrane permeabilization. Despite a wide range of applications, little is known about the electroporation threshold, which varies with membrane lipid composition. Here, using molecular dynamics simulations, we studied the response of dipalmitoyl-phosphatidylcholine, diphytanoyl-phosphocholine-ester and diphytanoyl-phosphocholine-ether lipid bilayers to an applied electric field. Comparing between lipids with acyl chains and methyl branched chains and between lipids with ether and ester linkages, which change drastically the membrane dipole potential, we found that in both cases the electroporation threshold differed substantially. We show, for the first time, that the electroporation threshold of a lipid bilayer depends not only on the “electrical” properties of the membrane, i.e., its dipole potential, but also on the properties of its component hydrophobic tails. 相似文献
113.
A novel function of eIF2alpha kinases as inducers of the phosphoinositide-3 kinase signaling pathway 下载免费PDF全文
Kazemi S Mounir Z Baltzis D Raven JF Wang S Krishnamoorthy JL Pluquet O Pelletier J Koromilas AE 《Molecular biology of the cell》2007,18(9):3635-3644
Phosphoinositide-3 kinase (PI3K) plays an important role in signal transduction in response to a wide range of cellular stimuli involved in cellular processes that promote cell proliferation and survival. Phosphorylation of the alpha subunit of the eukaryotic translation initiation factor eIF2 at Ser51 takes place in response to various types of environmental stress and is essential for regulation of translation initiation. Herein, we show that a conditionally active form of the eIF2alpha kinase PKR acts upstream of PI3K and turns on the Akt/PKB-FRAP/mTOR pathway leading to S6 and 4E-BP1 phosphorylation. Also, induction of PI3K signaling antagonizes the apoptotic and protein synthesis inhibitory effects of the conditionally active PKR. Furthermore, induction of the PI3K pathway is impaired in PKR(-/-) or PERK(-/-) mouse embryonic fibroblasts (MEFs) in response to various stimuli that activate each eIF2alpha kinase. Mechanistically, PI3K signaling activation is indirect and requires the inhibition of protein synthesis by eIF2alpha phosphorylation as demonstrated by the inactivation of endogenous eIF2alpha by small interfering RNA or utilization of MEFs bearing the eIF2alpha Ser51Ala mutation. Our data reveal a novel property of eIF2alpha kinases as activators of PI3K signaling and cell survival. 相似文献
114.
Nesrine Chaâri Mohamed Frikha Norhene Mezghanni Jaweher Ayadi Anis Chaouachi Nizar Souissi 《Biological Rhythm Research》2015,46(6):949-963
The purpose of this investigation was to assess the effects of rest interval following active warm-up (WU) durations on the diurnal variation of high-intensity cycling performance. Eleven male physical education students (22.6 ± 2.5 years; 179.2 ± 5.7 cm; 82.6 ± 9.6 kg; mean ± SD) participated in a cross-over randomized study, and they all underwent the 30-s Wingate test in the morning (08:00 h) and in the evening (18:00 h), after 5-min (WU5) and 15-min (WU15) warm-up durations, either with rest (WR), or without rest interval (NR) separating the WU at the onset of the high-intensity cycling exercise performance. The WU consisted of pedaling at a constant pace of 60 rpm against at 50% of the maximal aerobic power. The rest interval between the end of warm-up and the beginning of the anaerobic exercise was set at 5 min. Peak power (PP), mean power (MP), and the fatigue index (FI) were recorded. Likewise, heart rate, oral temperature (T), and rating of perceived exertion were registered at rest, at the end of the WU and just after the Wingate test. The ANOVA’s showed no main effect of the rest interval on PP, MP, FI, and T parameters. However, significant interactions (WU duration × time-of-day and recovery condition × WU duration) were recorded on both PP and MP parameters. PP and MP were higher in the afternoon compared to the morning with gains of 4.4 and 3.6%, respectively. In the morning sessions, the WU15 allows better improvement of muscular power, with either 0- or 5-min pre-exercise rest interval. However, in the afternoon sessions, both WU15 and WU5 durations allow better improvement of 30-s Wingate cycling performance in, respectively, WR and NR conditions. Therefore, athletes and coaches, as well as researchers, interested in high-intensity cycling exercise, should take into account the rest interval, the time-of-day, and the duration of warm-up when practicing, assessing, or interpreting data related to powerful lower limbs’ muscles contractions activities. 相似文献
115.
116.
Zoe Cournia Toby W. Allen Ioan Andricioaei Bruno Antonny Daniel Baum Grace Brannigan Nicolae-Viorel Buchete Jason T. Deckman Lucie Delemotte Coral del Val Ran Friedman Paraskevi Gkeka Hans-Christian Hege Jérôme Hénin Marina A. Kasimova Antonios Kolocouris Michael L. Klein Syma Khalid M. Joanne Lemieux Norbert Lindow Mahua Roy Jana Selent Mounir Tarek Florentina Tofoleanu Stefano Vanni Sinisa Urban David J. Wales Jeremy C. Smith Ana-Nicoleta Bondar 《The Journal of membrane biology》2015,248(4):611-640
117.
Nitraria retusa and Atriplex halimus (xero-halophytes) plants were grown in the range 0–800 mM NaCl while Medicago arborea (glycophyte) in 0–300 mM NaCl. Plants were harvested after 120 days of salt-treatment. The present study was designed to
study the effect of salinity on root, stem and leaf anatomy, water relationship, and plant growth in greenhouse conditions.
Salinity induced anatomical changes in the roots, stems and leaves. The cuticle and epidermis of N. retusa and A. halimus stems were unaffected by salinity. However, root anatomical parameters (root cross section area, cortex thickness and stele
to root area ratio), and stem anatomical parameters (stem cross section area and cortex area) were promoted at 100–200 mM
NaCl. Indicating that low to moderate salinity had a stimulating effect on root and stem growth of these xero-halophytic species.
At higher salinities, root and stem structures were altered significantly, and their percentages of reduction were higher
in A. halimus than in N. retusa whereas, in M. arborea, they were strongly altered as salinity rose. NaCl (100–300 mM) reduced leaf water content by 21.2–56.2% and specific leaf
area by 51–88.1%, while increased leaf anatomical parameters in M. arborea (e.g. increased thickness of upper and lower epidermis, palisade and spongy mesophyll, entire lamina, and increased palisade
to spongy mesophyll ratio). Similar results were evidenced in A. halimus leaves with salinity exceeding 100 mM NaCl. Leaves of N. retusa were thinner in salt-stressed plants while epidermis thickness and water content was unaffected by salinity. The size of
xylem vessel was unchanged under salinity in the leaf’s main vein of the three species while we have increased number in M. arborea leaf main vein in the range of 200–300 mM NaCl. A longer distance between leaf vascular bundle, a reduced size and increased
number of xylem vessel especially in stem than in root vascular system was evidenced in M. arborea treated plants and only at (400–800 mM) in the xero-halophytic species. The effects of NaCl toxicity on leaf, stem and root
ultrastructure are discussed in relation to the degree of salt resistance of these three species. Our results suggest that
both N. retusa and A. halimus show high tolerance to salinity while M. arborea was considered as a salt tolerant species. 相似文献
118.
The effect of four different NaCl concentrations (from 0 to 102 mM NaCl) on seedlings leaves of two corn (Zea mays L.) varieties (Aristo and Arper) was investigated through chlorophyll (Chl) a fluorescence parameters, photosynthesis, stomatal conductance, photosynthetic pigments concentration, tissue hydration and
ionic accumulation. Salinity treatments showed a decrease in maximal efficiency of PSII photochemistry (Fv/Fm) in dark-adapted leaves. Moreover, the actual PSII efficiency (ϕPSII), photochemical quenching coefficient (qp), proportion of PSII centers effectively reoxidized, and the fraction of light used in PSII photochemistry (%P) were also
dropped with increasing salinity in light-adapted leaves. Reductions in these parameters were greater in Aristo than in Arper.
The tissue hydration decreased in salt-treated leaves as did the photosynthesis, stomatal conductance (g
s) and photosynthetic pigments concentration essentially at 68 and 102 mM NaCl. In both varieties the reduction of photosynthesis
was mainly due to stomatal closure and partially to PSII photoinhibition. The differences between the two varieties indicate
that Aristo was more susceptible to salt-stress damage than Arper which revealed a moderate regulation of the leaf ionic accumulation. 相似文献
119.
ABSTRACT: BACKGROUND: Food industries aim to replace trans fat in their products by formulations having equivalent functionality and economic viability. Enzymatic transesterification can be a technological option to produce trans free fats targeting commercial applications. RESULTS: Palm stearin and palm olein blends in different ratios were enzymatically transesterified in a solvent free system using a Rhizopus oryzae lipase immobilised onto CaCO3 to produce a suitable fat for margarine formulation. Slip melting points and triacylglycerols profiles were evaluated upon transesterification. Results indicated that all transesterified blends had lower slip melting points than their non transesterified counterparts. Furthermore, the triacylglycerols profile showed a decrease in the concentration of the high melting point triacylglycerols. The rheological analysis showed that margarine prepared with the transesterified blend showed a better spreadability than that of a control margarine prepared with non transesterified fat. Adding powder of dry bark orange to margarine preparation improved its colour and fairly affected its spreadability and rheological behaviour. The margarine prepared with transesterified fat displayed a rheological behaviour that was comparable to that of commercial sample. CONCLUSIONS: This study is an ecofriendly approach to the utilization of relatively low value bioresources like palm stearin and palm olein for making margarine free of trans fatty acids that are now implicated as risk factor for heart diseases. 相似文献
120.
Ernesto Vargas Vladimir Yarov-Yarovoy Fatemeh Khalili-Araghi William A. Catterall Michael L. Klein Mounir Tarek Erik Lindahl Klaus Schulten Eduardo Perozo Francisco Bezanilla Beno?t Roux 《The Journal of general physiology》2012,140(6):587-594
Developing an understanding of the mechanism of voltage-gated ion channels in molecular terms requires knowledge of the structure of the active and resting conformations. Although the active-state conformation is known from x-ray structures, an atomic resolution structure of a voltage-dependent ion channel in the resting state is not currently available. This has motivated various efforts at using computational modeling methods and molecular dynamics (MD) simulations to provide the missing information. A comparison of recent computational results reveals an emerging consensus on voltage-dependent gating from computational modeling and MD simulations. This progress is highlighted in the broad context of preexisting work about voltage-gated channels.Voltage-gated K+ (KV) channels and prokaryotic voltage-gated Na+ (NaV) channels are formed by four subunits surrounding a central aqueous pore that allows ion permeation. Each subunit consists of six transmembrane α-helical segments called S1 to S6; the first four of these, S1–S4, constitute the voltage-sensor domain (VSD), whereas the S5–S6 segments assemble to form an ion-selective pore domain (see Fig. 1). The VSDs respond to changes in the potential difference across the cell membrane. When the membrane is depolarized, the VSD in each subunit undergoes a conformational transition from a resting to an activated state, and this information is communicated to the ion-conducting pore to promote its opening (Bezanilla et al., 1994; Zagotta et al., 1994). The activation of the VSD and opening of the pore are associated with the transfer of an electric charge ΔQ across the membrane, called the “gating charge” (Sigworth, 1994). Opening of the voltage-gated K+ channel Shaker corresponds to the outward translocation of a large positive charge on the order of 12–14 elementary charges (Schoppa et al., 1992). Four highly conserved arginines along S4 (R1, R2, R3, and R4) underlie the dominant contributions to the total gating charge of Shaker and appear to be mainly responsible for the coupling to the membrane voltage (Papazian et al., 1991; Aggarwal and MacKinnon, 1996; Seoh et al., 1996). The overall structure of eukaryotic voltage-gated Na+ channels, which are composed of four analogous subunits covalently linked in a single polypeptide, appears to be similar (Catterall, 2012).Open in a separate windowFigure 1.Overall view of the voltage-activated Kv1.2 K+ channel (Protein Data Bank accession no. 3LUT). (A) Two of the four subunits of the channel are displayed from a side view. The VSD comprises the transmembrane segments S1–S4, and the pore domain comprises the transmembrane segments S5–S6. (B) The tetramer is displayed from the extracellular side (each subunit is a different color). The two views are related by a 90° rotation.The nature of the conformational change within the VSD, and how it is communicated to the pore domain, is the key question that must be answered to explain voltage-dependent gating. Ultimately, we need to know the 3-D structure of the multiple resting and activated states of the VSDs and their relationship to the closed and open conformations of the pore at atomic resolution to understand the voltage-dependent gating mechanism in molecular terms. However, although x-ray crystallographic structures of the Kv1.2 channel, Kv1.2/Kv2.1 chimera, and bacterial NaVAb channels have provided information on the conformation of the active state (Long et al., 2005, 2007; Payandeh et al., 2011), no atomic resolution structure of a KV or NaV channel in the resting state is currently available. This has motivated the use of computations to provide the missing information about channel gating (Yarov-Yarovoy et al., 2006, 2012; Pathak et al., 2007; Bjelkmar et al., 2009; Delemotte et al., 2010, 2011; Khalili-Araghi et al., 2010, 2012; Schwaiger et al., 2011; Vargas et al., 2011; Jensen et al., 2012). These computational studies have relied on different approaches, including Rosetta modeling, a protein-folding method using knowledge-based potentials, and molecular dynamics (MD) simulations, consisting of propagating Newton’s classical equation of motion as a function of time using an all-atom force field. Remarkably, despite the considerable variations in computational methodologies and in template x-ray structures used, a highly consistent picture is emerging from these studies. Here we briefly review the most recent results in the broad context of preexisting work about voltage-gated channels.