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Based on the difference in the CD14 and CD16 expression, two subsets of monocytes were identified in human and other mammalian
blood. These subsets have different patterns of adhesion molecules and chemokine receptors that suggests the different mode
of their interaction with endothelium and tissue traffic. Here, we investigated the ability of CD14+CD16+ and CD14++CD16− monocytes to adhere to endothelial cell monolayer in presence or absence of pro- and anti-inflammatory cytokines. We demonstrated
that CD14+CD16+ monocytes had a higher level of adhesion to intact monolayer of endothelial cells than CD14++CD16− monocytes. Adhesion of CD14++CD16− and CD14+CD16+ monocytes significantly increased in the presence of TNFα or its combination with other cytokines. IFNγ and IL-4 alone did
not affect the adhesion of monocytes. These results show that CD14++CD16− and CD14+CD16+ monocytes can be recruited to the inflamed endothelium, but CD14+CD16+ monocytes adhere to endothelial cells without inflammations twice as strongly as CD14++CD16− monocytes. 相似文献
3.
The structures and stabilities of eleven N13
+ and N13
– isomers have been investigated with second-order Møller–Plesset (MP2) and density functional theory (DFT) methods. Five N13
+ isomers and six N13
– isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13
+ cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains. It is different from those of the N7
+ and N9
+ clusters, but similar to the N11
+ cluster. Meanwhile, the most stable N13
– structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N7
– and N9
– clusters, but also from the N11
– cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species.
Figure Optimized geometrical parameters of N13
+ isomer C-2
相似文献
4.
In two mountain ecosystems at the Alptal research site in central Switzerland, pulses of 15NO3 and 15NH4 were separately applied to trace deposited inorganic N. One forested and one litter meadow catchment, each approximately
1600 m2, were delimited by trenches in the Gleysols. K15NO3 was applied weekly or fortnightly over one year with a backpack sprayer, thus labelling the atmospheric nitrate deposition.
After the sampling and a one-year break, 15NH4Cl was applied as a second one-year pulse, followed by a second sampling campaign. Trees (needles, branches and bole wood),
ground vegetation, litter layer and soil (LF, A and B horizon) were sampled at the end of each labelling period. Extractable
inorganic N, microbial N, and immobilised soil N were analysed in the LF and A horizons. During the whole labelling period,
the runoff water was sampled as well. Most of the added tracer remained in both ecosystems. More NO3− than NH4+ tracer was retained, especially in the forest. The highest recovery was in the soil, mainly in the organic horizon, and in
the ground vegetation, especially in the mosses. Event-based runoff analyses showed an immediate response of 15NO3− in runoff, with sharp 15N peaks corresponding to discharge peaks. NO3− leaching showed a clear seasonal pattern, being highest in spring during snowmelt. The high capacity of N retention in these
ecosystems leads to the assumption that deposited N accumulates in the soil organic matter, causing a progressive decline
of its C:N ratio. 相似文献
5.
Acute coronary syndrome (ACS) is a group of clinical symptoms that results from complete or partial occlusive thrombus, which
is caused by coronary an atherosclerotic plaque rupture or erosion. According to a recent study, CD4+ CD28− T cells are found in atherosclerotic plaques and the peripheral circulation blood in patients with ACS, these cells play
an important role in plaque ruptures. CD4+ CD28− T cells are an unusual subset of helper cells, which expand and have harmful effects in ACS. In this review, we discuss the
current issues on the generation of CD4+ CD28− T cells and focus on their phenotypic and functional characteristics relevant to the development of cardiovascular events.
Targeting the CD4+ CD28− T cells subset in ACS could provide novel therapeutic means to prevent acute life-threatening coronary events. 相似文献
6.
A model of the HK2a subunit of the rabbit colonic H+, K+
ATPase has been generated using the crystal structure of the Ca+2 ATPase as a template. A pairwise sequence alignment of the deduced primary sequences of the two proteins demonstrated that they share 29% amino acid sequence identity and 47% similarity. Using O (version 7) the model of HK2a was constructed by interactively mutating, deleting, and inserting the amino acids that differed between the pairwise sequence alignment of the Ca+2 ATPase and HK2a. Insertions and deletions in the HK2a sequence occur in apparent extra-membraneous loop regions. The HK2a model was energy minimized and globally refined to a level comparable to that of the Ca+2 ATPase structure using CNS. The charge distribution over the surface of HK2a was evaluated in GRASP and possible secondary structure elements of HK2a were visualized in BOBSCRIPT. Conservation and placement of residues that may be involved in ouabain binding by the H+, K+
ATPase were considered and a putative location for the subunit was postulated within the structure.Figure Possible architecture of the HK2a subunit. The residue in green is the lysine (position 517, Fig. 1) that lies in the nucleotide binding pocket and the residue in red is the aspartic acid at the phosphorylation site (position 385). Based on an alignment with the Ca+2 ATPase, ten transmembrane helices were modeled into HK2a. The ten transmembrane helices are drawn as rods and shown in different colors for clarity. From left to right, the transmembrane helix designations are M10 (blue), M7 (gray), M8 (purple), M9 (orange), M5 (pink), M6 (green), M3 (brown), M4 (cyan), M2 (teal), and M1 (almond). 相似文献
7.
V. E. Yurinskaya T. S. Goryachaya A. A. Rubashkin A. V. Shirokova A. A. Vereninov 《Cell and Tissue Biology》2010,4(5):457-463
The K+, Na+, and Cl− balance and K+ (Rb+) and 36Cl− fluxes in U937 cells induced to apoptosis by 0.2 or 1 μM staurosporine were studied using flame emission and radioisotope
techniques. It is found that two-thirds of the total decrease in the amount of intracellular osmolytes in apoptotic cells
is accounted for by monovalent ions and one-third consists of other intracellular osmolytes. A decrease in the amount of monovalent
ions results from a decrease in the amount of K+ and Cl− and an increase in the Na+ content. The rate of 36Cl−, Rb+ (K+), and 22Na+ equilibration between cells and the medium was found to significantly exceed the rate of apoptotic change in the cellular
ion content, which indicates that unidirectional influxes and effluxes during apoptosis may be considered as being in near
balance. The drift of the ion flux balance in apoptosis caused by 0.2 μM staurosporine was found to be associated with the
increased ouabain-resistant Rb+ (K+) channel influx and insignificantly altered the ouabain-sensitive pump influx. Severe apoptosis induced by 1 μM staurosporine
is associated with reduced pump fluxes and slightly changed channel Rb+ (K+) fluxes. In apoptotic cells, the 1.4–1.8-fold decreased Cl− level is accompanied by a 1.2–1.6-fold decreased flux. 相似文献
8.
V. A. Vodeneev E. K. Akinchits L. A. Orlova V. S. Sukhov 《Russian Journal of Plant Physiology》2011,58(6):974-981
The contributions of Ca2+, H+, and Cl− in generation of variation potentials (VP) in 3- to 4-week-old pumpkin (Cucurbita pepo L., cv. Mozoleevskaya) plants were assessed. During VP generation, transient alkalinization of the medium around the stem
was recorded with a potentiometric method. The pH changes were kinetically similar to the electric potential changes and were
apparently due to temporal suppression of the plasma-membrane electrogenic H+ pump. These data and the observed inhibition of VP in the stem zone treated locally with a metabolic inhibitor (NaN3) indicate that the VP generation is related to the reversible suppression of the H+-pump. The anion channel blocker (ethacrynic acid) decelerated significantly the front slope of VP and reduced the VP amplitude.
A short-term increase in external Cl− concentration around the stem was observed during potential transients representing the VP front slope and the pulses integrated
into VP. The removal of Ca2+ from extracellular medium inhibited the VP generation. It is proposed that Ca2+ plays a role in activation of anion channels and in the H+-pump inactivation. The VP generation is probably determined by a complex mechanism, with contributions from passive ion fluxes
(Ca2+, Cl−) moving along the electrochemical gradients and from changes in the electrogenic pump activity. 相似文献
9.
The Na+/Mg2+ exchanger represents the main Mg2+ extrusion mechanism operating in mammalian cells including hepatocytes. We have previously reported that this exchanger, located in the basolateral domain of the hepatocyte, promotes the extrusion of intravesicular trapped Mg2+ for extravesicular Na+ with ratio 1. This electrogenic exchange is supported by the accumulation of tetraphenyl-phosphonium within the vesicles at the time when Mg2+ efflux occurs. In this present study, the role of extra- and intra-vesicular Cl? on the Na+/Mg2+ exchange ratio was investigated. The results reported here suggest that Cl? ions are not required for the Na+ to Mg2+ exchange to occur, but the stoichiometry ratio of the exchanger switches from electrogenic (1Na in + :1 Mg out 2+ ) in the presence of intravesicular Cl? to electroneutral (2Na in + :1 Mg out 2+ ) in their absence. In basolateral liver plasma membrane vesicles loaded with MgCl2 labeled with 36Cl?, a small but significant Cl? efflux (~30 nmol Cl?/mg protein/1 min) is observed following addition of NaCl or Na-isethionate to the extravesicular medium. Both Cl? and Mg2+ effluxes are inhibited by imipramine but not by amiloride, DIDS, niflumic acid, bumetanide, or furosemide. In vesicles loaded with Mg-gluconate and stimulated by Na-isethionate, an electroneutral Mg2+ extrusion is observed. Taken together, these results suggest that the Na+/Mg2+ exchanger can operate irrespective of the absence or the presence of Cl? in the extracellular or intracellular environment. Changes in trans-cellular Cl? content, however, can affect the modus operandi of the Na+/Mg2+ exchanger, and consequently impact "cellular" Na+ and Mg2+ homeostasis as well as the hepatocyte membrane potential. 相似文献
10.
Brown IE Mashayekhi M Markiewicz M Alegre ML Gajewski TF 《Apoptosis : an international journal on programmed cell death》2005,10(1):5-11
Maintenance of a sufficient population of naïve CD8+ T cells in the peripheral lymphoid compartment is critical for immunocompetence. Peripheral T cell number is a function of T cell generation, survival, and death. Homeostasis, a critical balance between survival and death, must exist to prevent either lymphopenia or lymphocytosis. In the current review, we discuss known requirements for the survival of naïve peripheral CD8+ T cells as well as mechanisms of death when survival signals are lost. We also discuss associations between survival and homeostasis-driven proliferation, and highlight the gaps in our knowledge of these critical processes. 相似文献
11.
Jennifer M Kress-Bennett Garth D Ehrlich Ashley Bruno J Christopher Post Fen Z Hu Thomas F Scott 《BMC neurology》2011,11(1):155
Background
There are a lack of biomarkers which can be used to predict clinical outcomes for multiple sclerosis (MS) patients receiving interferon beta (IFN-β). Thus the objective of this study was to characterize changes in CD4+ T-lymphocyte expression in an unbiased manner following initiation of intramuscular (IM) IFN-β-1a treatment, and then to verify those findings using marker-specific assays. 相似文献12.
MEMBRANE enzymes, because of their lipid content, are insoluble in water and usually solubilized as micelles in aqueous solution by detergents for biochemical study. Direct study of lipid components by means of organic liquids in which they dissolve leads at once to the denaturation of the enzyme. At temperatures appreciably colder than 0° C, however, organic solvents may leave enzymatic activity intact1–3, making it possible to study enzyme reactions. 相似文献
13.
14.
Bone marrow-derived cells have been postulated as a source of multipotent mesenchymal stem cells (MSC). However, the whole
fraction of MSC remains heterogeneous and the expansion of primitive subset of these cells is still not well established.
Here, we optimized the protocol for propagating the low-adherent subfraction of MSC which results in long-term expansion of
population characterized by CD45−CD14+CD34+ phenotype along with expression of common MSC markers. We established that the expanded MSC are capable of differentiating
into endothelial cells highly expressing angiogenic markers and exhibiting functional properties of endothelium. Moreover,
we found these cells to be multipotent and capable of giving rise into cells from neuronal lineages. Interestingly, the expanded
MSC form characteristic cellular spheres in vitro indicating primitive features of these cells. In sum, we isolated the novel multipotent subpopulation of CD45−CD14+ CD34+ bone marrow-derived cells that could be maintained in long-term culture without losing this potential. 相似文献
15.
We investigate the electrophysiological salt stress response of the salt-sensitive charophyte Chara australis as a function of time in saline artificial pond water (saline APW) containing 50 mM NaCl and 0.1 mM CaCl2. The effects are due to an increase in Na+ concentration rather than an increase in Cl− concentration or medium osmolarity. A previous paper (Shepherd et al. Plant Cell Environ 31:1575–1591, 2008) described the
rise in the background conductance and inhibition of proton pumping in saline APW in the first 60 min. Here we investigate
the shift of membrane potential difference (PD) to levels above −100 mV and the change of shape of the current–voltage (I/V)
profiles to upwardly concave. Arguing from thermodynamics, the I/V characteristics can be modeled by channels that conduct
H+ or OH−. OH− was chosen, as H+ required an unrealistic increase in the number/permeability of the channels at higher pH levels. Prolonged exposure to saline
APW stimulated opening of more OH− channels. Recovery was still possible even at a PD near −50 mV, with partial return of proton pumping and a decrease in OH− current following APW wash. Upon change of pH from 7 to 9, the response was consistent with previously observed I/V characteristics
of OH− channels. For a pH change to 6, the response was transient before channel closure but could still be modeled. The consequences
of opening of H+ or OH− channels while the cell is under salt stress are discussed. 相似文献
16.
Rüdiger Ettrich Milan Melichercik Jan Teisinger Olga Ettrichova Rita Krumscheid Katerina Hofbauerova Peter Kvasnicka Wilhelm Schoner Evzen Amler 《Journal of molecular modeling》2001,7(6):184-192
Homology modeling of the complete structure of the large cytoplasmic loop between the fourth and fifth transmembrane segments (H4–H5 loop) of the subunit of Na+/K+-ATPase is reported. The deduced amino acid sequence shows high sequence identity and homology to the Ca2+-ATPase (32.8% identity and 53.3% similarity in our alignment), whose tertiary structure has been solved recently at 2.6-Å resolution by X-ray crystallography. This high homology allowed the construction of a model structure using the MODELLER program. Refinement was achieved through interactive visual and algorithmic analysis and minimization with the TRIPOS force field included in the SYBYL/MAXIMIN2 module. The docking of ATP as a substrate into the active site of the model was explored with the AUTODOCK program followed by molecular mechanics optimization of the most interesting complexes. Thus, the docking of ATP into the resulting model of the H4–H5 loop gave evidence for the existence of one ATP binding site only. We were able to specify Cys549, Phe548, Glu505, Lys501, Gln482, Lys480, Ser477, Phe475 and Glu446 as parts of the ATP binding site with Lys501 located in the depth of the positively charged binding pocket.Electronic Supplementary Material available. 相似文献
17.
V. A. Belyaev D. A. Kozlov A. A. Terent’ev A. E. Trenin 《Plasma Physics Reports》2017,43(10):1039-1041
A method for determining the lifetime of unstable ions is described. The method is based on measuring the decrease in the ion beam current onto a fixed detector with increasing path length of the ion beam from the ion source to the detector. The measurements performed for D? 2 and HD? molecular ions have shown that their lifetimes are 3.5 ± 0.1 and 4.4 ± 0.1 μs, respectively. 相似文献
18.
A confined aquifer in the Malm Karst of the Franconian Alb, South Germany was investigated in order to understand the role of the vadose zone in denitrifiaction processes. The concentrations of chemical tracers Sr2+ and Cl– and concentrations of stable isotope 18O were measured in spring water and precipitation during storm events. Based on these measurements a conceptual model for runoff was constructed. The results indicate that pre-event water, already stored in the system at the beginning of the event, flows downslope on vertical and lateral preferential flow paths. Chemical tracers used in a mixing model for hydrograph separation have shown that the pre-event water contribution is up to 30%. Applying this information to a conceptual runoff generation model, the values of 15N and 18O in nitrate could be calculated. Field observations showed the occurence of significant microbial denitrification processes above the soil/bedrock interface before nitrate percolates through to the deeper horizon of the vadose zone. The source of nitrate could be determined and denitrification processes were calculated. Assuming that the nitrate reduction follows a Rayleigh process one could approximate a nitrate input concentration of about 170 mg/l and a residual nitrate concentration of only about 15%. The results of the chemical and isotopic tracers postulate fertilizers as nitrate source with some influence of atmospheric nitrate. The combined application of hydrograph separation and determination of isotope values in 15N and 18O of nitrate lead to an improved understanding of microbial processes (nitrification, denitrification) in dynamic systems. 相似文献
19.
The limits of resolution that can be obtained in 1H–15N 2D NMR spectroscopy of isotopically enriched nanocrystalline proteins are explored. Combinations of frequency switched Lee–Goldburg (FSLG) decoupling, fast magic angle sample spinning (MAS), and isotopic dilution via deuteration are investigated as methods for narrowing the amide 1H resonances. Heteronuclear decoupling of 15N from the 1H resonances is also studied. Using human ubiquitin as a model system, the best resolution is most easily obtained with uniformly 2H and 15N enriched protein where the amides have been exchanged in normal water, MAS at 20 kHz, and WALTZ-16 decoupling of the 15N nuclei. The combination of these techniques results in average 1H lines of only 0.26 ppm full width at half maximum. Techniques for optimizing instrument stability and 15N decoupling are described for achieving the best possible performance in these experiments. 相似文献
20.
M. A. Breygina N. P. Matveyeva D. S. Andreyuk I. P. Yermakov 《Russian Journal of Developmental Biology》2012,43(2):85-93
We studied the possibility of K+ and Cl− efflux from tobacco pollen grains during their activation in vitro or on the stigma of a pistil. For this purpose the X-ray
microanalysis and spectrofluorometry were applied. We found that the relative content of potassium and chlorine in the microvolume
of pollen grain decreases during its hydration and activation on stigma. Efflux of these ions was found both in vivo and in
vitro. In model in vitro experiments anion channel inhibitor NPPB ((5-nitro-2-(3-phenylpropylamino) benzoic acid) in the concentration
that was blocking pollen germination, reduced Cl− efflux; potassium channel inhibitor TEA (tetraethylammonium chloride) partially reduced K+ efflux and lowered the percent of activated cells. Another blocker of potassium channels Ba2+ caused severe decrease in cell volume and blocked the activation. In general, the obtained data demonstrates that the initiation
of pollen germination both in vivo and in vitro involves the activation of K+ and Cl− release. An important role in these processes is played by NPPB-, TEA- and Ba2+-sensitive plasmalemma ion channels. 相似文献