Inflammatory response of macrophages in infection.

BACKGROUND: Macrophages are widely-distributed innate immune cells playing diverse roles in various physiological and pathological processes. The primary function of macrophages is to phagocytize and clear invading pathogens. DATA SOURCES: A systematic search of PubMed was performed to identify relevant studies in English language literature using the key words such as macrophage and inflammation. A total of 122 articles related to inflammatory response of macrophages in infection were systematically reviewed. RESULTS: The inflammatory responses of macrophages triggered by infection comprise four interrelated phases: recognition of pathogen-associated molecular patterns by pattern-recognition receptors expressed on/in macrophages; enrichment of quantity of macrophages in local infected tissue by recruitment of circulating monocytes and/or in situ proliferation; macrophage-mediation of microbicidal activity and conversion to anti-inflammatory phenotype to terminate anti-infectious response and to promote tissue repair. Complicated regulation of macrophage activation at molecular level recognized in the past decade is also reviewed, including intracellular multiple signaling molecules, membrane molecules, microRNAs and even epigenetic-associated molecules. CONCLUSION: The inflammatory response of macrophages in infection is an orderly and complicated process under elaborate regulation at molecular level.

Real-time, high-resolution study of nanocrystallization and fatigue cracking in a cyclically strained metallic glass.

Metallic glasses (MGs) exhibit greater elastic limit and stronger resistance to plastic deformation than their crystalline metal counterparts. Their capacity to withstand plastic straining is further enhanced at submicrometer length scales. For a range of microelectromechanical applications, the resistance of MGs to damage and cracking from thermal and mechanical stress or strain cycling under partial or complete constraint is of considerable scientific and technological interest. However, to our knowledge, no real-time, high-resolution transmission electron microscopy observations are available of crystallization, damage, and failure from the controlled imposition of cyclic strains or displacements in any metallic glass. Here we present the results of a unique in situ study, inside a high-resolution transmission electron microscope, of glass-to-crystal formation and fatigue of an Al-based MG. We demonstrate that cyclic straining progressively leads to nanoscale surface roughening in the highly deformed region of the starter notch, causing crack nucleation and formation of nanocrystals. The growth of these nanograins during cyclic straining impedes subsequent crack growth by bridging the crack. In distinct contrast to this fatigue behavior, only distributed nucleation of smaller nanocrystals is observed with no surface roughening under monotonic deformation. We further show through molecular dynamics simulation that these findings can be rationalized by the accumulation of strain-induced nonaffine atomic rearrangements that effectively enhances diffusion through random walk during repeated strain cycling. The present results thus provide unique insights into fundamental mechanisms of fatigue of MGs that would help shape strategies for material design and engineering applications.

Approaching the ideal elastic limit of metallic glasses.

The ideal elastic limit is the upper bound to the stress and elastic strain a material can withstand. This intrinsic property has been widely studied for crystalline metals, both theoretically and experimentally. For metallic glasses, however, the ideal elastic limit remains poorly characterized and understood. Here we show that the elastic strain limit and the corresponding strength of submicron-sized metallic glass specimens are about twice as high as the already impressive elastic limit observed in bulk metallic glass samples, in line with model predictions of the ideal elastic limit of metallic glasses. We achieve this by employing an in situ transmission electron microscope tensile deformation technique. Furthermore, we propose an alternative mechanism for the apparent 'work hardening' behaviour observed in the tensile stress-strain curves.

Enhanced phosphorylation of MAPKs by NE promotes TNF-α production by macrophage through α adrenergic receptor.

The aim of this study was to investigate whether norepinephrine (NE) could regulate macrophage production of tumor necrosis factor alpha (TNF-α) by influencing the phosphorylation of mitogen-activated protein kinases (MAPKs). Primary macrophages from male BALB/c mice were applied to explore the mechanism by which NE influences the the secretion of TNF-α when macrophages were activated by lipopolysaccharides (LPS). We found that NE could increase crophage production of TNF-α when macrophages were activated by LPS, and this effect could be inhibited by α adrenergic antagonist phentolamine. Also, NE could increase the phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinases (ERK), and p38, through α receptor. Furthermore, JNK inhibitor SP600125, ERK inhibitor U0126, and p38 inhibitor SB203580 could all partially counteract NE's effect on the phosphorylation of MAPKs, as well as TNF-α production by macrophages. This study revealed that as macrophages were activated by LPS, NE promoted the secretion of inflammatory factors by increasing the phosphorylation of MAPKs through an α receptor-dependent pathway. Our results provide the evidence of a relationship between stress and diseases, as well as the mechanism by which stress induces or affects the inflammation-related diseases.

Uridine 5'-triphosphate (UTP) protects against cerebral ischemia reperfusion injury in rats.

AIMS: To test the hypothesis that uridine 5'-triphosphate (UTP) had a protective effect on cerebral ischemia reperfusion (IR) injury in rats. METHODS: Ischemia was induced by intraluminal suture of middle cerebral artery occlusion (MCAO). UTP solution was delivered through an indwelling tail venous catheter via microinfusion pump 30 min after the occlusion of MCA at a rate of 0.5 ml/100 g/min. Neurological deficit score (NDS) and brain water content were determined 24 h after reperfusion. Infarct volume was determined by 2,3,5-triphenyl-tetrazolium chloride (TTC) staining and magnetic resonance imaging (MRI), and nerve cell death was studied under an electron microscope. RESULTS: There was a dose-dependent relationship among 10, 30 and 90 microg/kg UTP. The 90 microg/kg UTP had the best protective effect among the 3 groups. We compared 90 microg/kg UTP group with normal saline group and found that UTP had a protective effect on cerebral IR by the results of TTC staining (15.9% vs 30.5%, P<0.01). MRI at 6, 30 and 54 h after reperfusion showed smaller infarct volume in 90 microg/kg group compared with 0 microg/kg group (283.5, 352.1, 367.45 mm(3) vs 401.36, 576.75 and 677.11 mm(3), respectively), and electron microscope showed less nerve cell death in 90 microg/kg group compared with 0 microg/kg group. CONCLUSION: UTP has a dose-dependent protective effect on cerebral IR.

Effects of sodium content and calcination temperature on the morphology, structure and photocatalytic activity of nanotubular titanates.

Titanate nanotubes (TNT) were prepared via a hydrothermal treatment of TiO(2) powders (P25) in a 10 M NaOH solution at 150 degrees C for 24 h and subsequently washed with HCl aqueous solution of different concentrations (0.1, 0.01, and 0.001 N). Samples with different contents of remnant sodium in nanotubes were characterized, as synthesized and after heat-treatment, by transmission electron microscopy, X-ray diffraction, and nitrogen adsorption-desorption isotherms. The photocatalytic activity of TNT was evaluated by photocatalytic oxidation of basic dye (basic violet 10 (BV10)) in water solution. It was found that if the sodium was not completely exchanged with proton, the removal of sodium increased the specific surface area (and pore volume), while the thermal stability was reduced. When the sodium content of TNT was approximately 0 wt% (nearly complete proton exchange), the nanotubular structure of titanates might be destroyed. The effects of the alterations of microstructures induced by the exchange of sodium and heat-treatment on the photocatalytic activity of TNT were discussed with the variations of specific surface area, pore volume, and the amounts of anatase phase in TNT.

Application of titanate nanotubes for dyes adsorptive removal from aqueous solution.

The potential of adsorptive removal of basic dyes with titanate nanotubes (TNTs) and acid dyes with surfactant (hexadecyltrimethylammonium (HDTMA) chloride)-modified TNTs were investigated. TNTs were prepared via a hydrothermal method and subsequently washed with HCl aqueous solutions of different concentrations. The prepared TNTs were then mediated by the HDTMA ions through the cation exchange process. Effects of acid washing and HDTMA-modified process on the revolution of microstructure and surface chemistry characteristics of TNTs were characterized with XRD, nitrogen adsorption-desorption isotherms, and FTIR. The adsorption capacities of two basic dyes (two acid dyes) on TNTs (their HDTMA-modified version) at initial dye concentration of 2000 mg/L were measured. It was experimentally concluded that if the amount of Na(+) in the TNTs was not very low, the TNTs and their HDTMA-modified version might be a good adsorbent for the removal of basic and acid dyes from aqueous solution through the cation and anion exchange mechanism, respectively. The adsorption capacity for basic and acid dyes could reach 380 and 400 mg/g, respectively.

Application of MCM-41 for dyes removal from wastewater.

The adsorption of three basic dyes (Rhodamine B (RB), Crystal Violet (CV), and Methylene Green (MG)) and two acid dyes (Acid Red 1 (AR1) and Erioglaucine (EG)) onto MCM-41 was studied to examine the potential of MCM-41 for the removal of dyes from water solution. The revolution of pore structure and surface chemical characteristics of MCM-41 induced by dyes adsorption was characterized based on the analyses of XRD patterns, FTIR spectra, and nitrogen adsorption-desorption isotherms. The adsorption capacity of MCM-41 for the five dyes followed a decreasing order of RB>CV>MG>EG approximately AR1. It was experimentally concluded that if the dyes adsorption did not introduce a serious disorder on the pore structure of MCM-41 (such as RB adsorption), MCM-41 might be a good adsorbent for the removal of basic dyes from water solution. The fitness of both Langmuir and Freundlich adsorption model on describing the equilibrium isotherms of three basic dyes was examined. The suitability of both pseudo-second-order kinetic model and the intraparticle diffusion model for the description of the kinetic data was investigated, from which the adsorption mechanism was examined.

Improved surface-enhanced Raman scattering on electrochemically roughened silver substrates prepared in bielectrolyte solutions.

In this work, the effect of supplemental LiClO(4) electrolytes in KCl solutions used in roughening silver substrates by electrochemical triangular-wave oxidation-reduction cycles (ORC) on surface-enhanced Raman scattering (SERS) was first investigated. To prepare SERS-active substrates by ORC procedures, electrolytes of KCl were generally employed. In contrast, LiClO(4) ones were unsuitable for producing SERS-active substrates. Encouragingly, SERS of Rhodamine 6G (R6G) adsorbed on the roughened Ag substrate prepared in an aqueous solution containing KCl and LiClO(4) electrolytes exhibits a higher intensity by one order of magnitude, as compared with that of R6G adsorbed on a roughened Ag substrate prepared in a solution only containing KCl. Further investigations indicate that the oxidation state of Cl on the roughened Ag substrate demonstrates decided effects on this improved SERS.

Adsorption of basic dyes onto MCM-41.

The adsorption of two basic dyes, Basic Green 5 (BG5) and Basic Violet 10 (BV10), onto MCM-41 was studied to examine the possible effect of interactions between large adsorbates and MCM-41 on the pore structure stability of MCM-41 and the potential of MCM-41 for the removal of basic dyes from wastewater. The revolutions of surface characteristics and pore structure of MCM-41 induced by dyes adsorption were characterized based on the analyses of the nitrogen isotherms, the XRD patterns, and the FTIR spectra. It was experimentally concluded that when the effect of interactions between large dyes (such as BV10) and MCM-41 on the pore structure stability of MCM-41 was insignificant, MCM-41 might be a good adsorbent for the removal of basic dyes from wastewater. The adsorption of BV10 on MCM-41 with respect to contact time, pH, and temperature was then measured to provide more information about the adsorption characteristics of MCM-41. Both Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the pseudo-second-order kinetic model was used to describe the kinetic data, from which some adsorption thermodynamic parameters were also evaluated.

Scaling characteristics in ozone concentration time series (OCTS).

One-year series of hourly average ozone observations, which were obtained from urban and national park air monitoring stations at Taipei (Taiwan), were analyzed by means of descriptive statistics and fractal methods to examine the scaling structures of ozone concentrations. It was found that all ozone measurements exhibited the characteristic right-skewed frequency distribution, cyclic pattern, and long-term memory. A mono-fractal analysis was performed by transferring the ozone concentration time series (OCTS) into a useful compact form, namely, the box-dimension (D(B))-threshold (T(h)) and critical scale (C(S))-threshold (T(h)) plots. Scale invariance was found in these time series and the box dimension was shown to be a decreasing function of the threshold ozone level, implying the existence of multifractal characteristics. To test this hypothesis, the OCTS were transferred into the multifractal spectra, namely, the tau(q)-q plots. The analysis confirmed the existence of multifractal characteristics in the investigated OCTS. A simple two-scale Cantor set with unequal scales and weights was then used to fit the calculated tau(q)-q plots. This model fitted remarkably well the entire spectrum of scaling exponents for the examined OCTS. Because the existence of chaos behavior in OCTS has been reported in the literature, the possibility of a chaotic multifractal approach for OCTS characterization was discussed.

Effects of exchanged surfactant cations on the pore structure and adsorption characteristics of montmorillonite.

Ca-montmorillonite (Ca-Mont) was exchanged with two quaternary amines, tetramethylammonium (TMA) chloride and hexadecyltrimethylammonium (HDTMA) bromide, to study the surfactant ion exchange effect on the pore structure, surface characteristics, and adsorption properties of montmorillonite. The revolution of both the surface area and pore structure of montmorillonite was characterized based on classical and fractal analyses of the nitrogen isotherms as well as the XRD patterns. The change of surface characteristics was identified from FTIR patterns and zeta-potential plots. The adsorption isotherms of acid dye, Amido Naphthol Red G (AR1), were then measured to identify the effects of the ion-exchange process on the adsorption properties of montmorillonite. It was found that the exchange processes might induce an increase or decrease in the surface area, pore size, pore volume, and surface fractal dimension D of montmorillonite, depending on the size, the molecular arrangement, and the degree of hydration of the exchanged ion in the clay. On the other hand, it was also found that the hydrophobic bonding by conglomeration of large C(16) alkyl groups associated with HDTMA could cause positive charge development on the surface of montmorillonite, which was not observed for TMA-modified montmorillonite (TMM). The effects of the alteration of the surface characteristics of montmorillonites on their adsorption selectivity for acid dye were discussed.

Adsorption of basic dyes onto montmorillonite.

Ca-montmorillonite (Ca-Mont) was exchanged with titanium cations and the adsorption equilibrium and kinetics of Basic Green 5 (BG5) and Basic Violet 10 (BV10) on these montmorillonites were measured to examine the ion-exchange effects on the basic dyes adsorption. The relationship between the dye adsorption and the alteration of pore structures of montmorillonite induced by ion-exchange processes was discussed. Moreover, the changes in the surface and pore structure of montmorillonites during adsorption were characterized based on classical and fractal analyses of the nitrogen adsorption isotherms as well as the XRD patterns. The decrease in BET surface area of montmorillonites after adsorption of dyes was interpreted in terms of both the coverage of some surface roughness (surface screening effect) and the inhibition of the movement of nitrogen molecule into some pores (pore blocking effect). The surface fractal dimension D was used to examine whether or not the surface screening effect exists and the pore blocking effect was examined with the changes of mean pore size before and after adsorbing basic dyes.