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Activation Pathways (activation + pathway)
Selected AbstractsAgC10, a mucin from Trypanosoma cruzi, destabilizes TNF and cyclooxygenase-2 mRNA by inhibiting mitogen-activated protein kinase p38EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 6 2004Pilar Alcaide Abstract Secretion of proinflammatory mediators by activated macrophages plays an important role in the immune response to Trypanosoma cruzi. We have previously reported that AgC10, a glycosylphosphatidylinositol-anchored mucin from T. cruzi, inhibits TNF secretion by activated macrophages (de Diego, J., Punzon, C., Duarte, M. and Fresno, M., Alteration of macrophage function bya Trypanosoma cruzi membrane mucin. J. Immunol. 1997. 159: 4983,4989). In this report we have further investigated the molecular mechanisms underlying this inhibition. AgC10 inhibited TNF, IL-10 and cyclooxygenase-2 (COX-2) synthesis by macrophages activated with LPS or LPS plus IFN-, in a dose-dependent manner. AgC10 did not affect other aspects of macrophage activation induced by LPS, such as inducible nitric oxide synthase (iNOS) expression. AgC10 also had no effect on TNF or COX-2 transcription or the induction of their promoters but inhibited the stability of TNF and COX-2 mRNA, which are regulated post-transcriptionally by the mitogen-activated protein kinase (MAPK) p38 pathway. AgC10 was found to inhibit both the activation and the activity of p38 MAPK, since MAPK activated protein kinase-2 (MAPKAP-K2 or MK-2) phosphorylation was also strongly inhibited. This led to TNF and COX-2 mRNA destabilization. In contrast, AgC10 did not affect p38 activation induced by TNF. Furthermore, AgC10 inhibition must lie upstream in the MAPK activation pathway by LPS, since this mucin also inhibited extracellularly regulated kinase (ERK) and Jun kinase (JNK)activation. [source] CD66a (CEACAM1) expression by mouse natural killer cellsIMMUNOLOGY, Issue 4 2008Gaëtan Thirion Summary CD66a (CEACAM1), an adhesion molecule that has regulatory function on T lymphocytes, was found to be expressed on a minority of mouse natural killer (NK) cells, especially in the liver. CD66a expression on NK cells depended on their differentiation stage, with highest levels on immature CD49b,NK cells. Expression of CD66a on NK cells was strongly enhanced by in vitro activation with interleukin-12 (IL-12) and IL-18. However, in vivo NK cell stimulation by infection with lactate dehydrogenase-elevating virus did not lead to strong CD66a expression, even on activated interferon--,-producing NK cells. These results indicate that CD66a expression is differently regulated, depending on the NK cell activation pathway, which may lead to distinct regulatory mechanisms of the functional subpopulations of these cells. [source] Apoptosis and Cardiopulmonary BypassJOURNAL OF CARDIAC SURGERY, Issue 2 2007M.S., Miljenko Kova Apoptotic index (AI) obtained with in situ terminal deoxynucleotidyl transferase-labeled dUTP nick end labeling (TUNEL) method and Bak protein expression were compared. Patients and Methods: Twenty consecutive patients who underwent coronary artery bypass surgery, myocardial samples from the right atrium were taken in three stages: before cannulation (the first sample group), after declamping (the second sample group), and 20 minutes after reperfusion (the third sample group). The percentage of apoptotic cells was determined by TUNEL method. Expression of Bak protein was immunohistochemically analyzed. Intermittent ischemia and moderate hypothermia were used as methods of myocardial management during surgery. A statistical analysis was performed by using the Friedman ANOVA analysis of variances, the Kendall coefficient of concordance and the Wilcoxon matched pair test. Results: In the first sample group mean value of Bak expression was 2.61 ± 2.18, compared with AI 5.38 ± 3.58, after declamping (the second sample group) the mean value of Bak expression was 4.31 ± 2.68 while AI was 7.63 ± 4.38 and after 20 minutes of reperfusion in the third sample group mean value of Bak expression was 8.89 ± 4.45, while AI was 15.6 ± 8.45. When compared by using Wilcoxon matched pair test two methods significantly correlated, p > 0.0001. Conclusion: The positive correlation between AI obtained by TUNEL method and expression of Bak protein may suggest that apoptosis is activated mainly through mitochondrial activation pathway in ischemic reperfusion injury. The results suggest that ischemic reperfusion injury increases the AI in the right atrial tissue. If so, immunohistochemical expression of Bak protein could be used as a marker of myocardial ischemia induced injury. [source] Non-conventional signal transduction by type 1 interferons: The NF-,B pathwayJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2007Ziyun Du Abstract Type I interferons (IFNs) regulate diverse cellular functions by modulating the expression of IFN-stimulated genes (ISGs) through the activation of the well established signal transduction pathway of the Janus Kinase (JAK) and signal transducers and activators of transcription (STAT) proteins. Although the JAK,STAT signal transduction pathway is critical in mediating IFN's antiviral and antiproliferative activities, other signaling pathways are activated by IFNs and regulate cellular response to IFN. The NF-,B transcription factor regulates the expression of genes involved in cell survival and immune responses. We have identified a novel IFN mediated signal pathway that leads to NF-,B activation and demonstrate that a subset of ISGs that play key roles in cellular response to IFN is regulated by NF-,B. This review focuses on the IFN-induced NF-,B activation pathway and the role of NF-,B in ISG expression, antiviral activity and apoptosis, and the therapeutic application of IFN in cancer and infectious disease. J. Cell. Biochem. 102: 1087,1094, 2007. © 2007 Wiley-Liss, Inc. [source] Alcohol Stimulates Ciliary Motility of Isolated Airway Axonemes Through a Nitric Oxide, Cyclase, and Cyclic Nucleotide-Dependent Kinase MechanismALCOHOLISM, Issue 4 2009Joseph H. Sisson Background:, Lung mucociliary clearance provides the first line of defense from lung infections and is impaired in individuals who consume heavy amounts of alcohol. Previous studies have demonstrated that this alcohol-induced ciliary dysfunction occurs through impairment of nitric oxide (NO) and cyclic nucleotide-dependent kinase-signaling pathways in lung airway ciliated epithelial cells. Recent studies have established that all key elements of this alcohol-driven signaling pathway co-localize to the apical surface of the ciliated cells with the basal bodies. These findings led us to hypothesize that alcohol activates the cilia stimulation pathway at the organelle level. To test this hypothesis we performed experiments exposing isolated demembranated cilia (isolated axonemes) to alcohol and studied the effect of alcohol-stimulated ciliary motility on the pathways involved with isolated axoneme activation. Methods:, Isolated demembranated cilia were prepared from bovine trachea and activated with adenosine triphosphate. Ciliary beat frequency, NO production, adenylyl and guanylyl cyclase activities, cAMP- and cGMP-dependent kinase activities were measured following exposure to biologically relevant concentrations of alcohol. Results:, Alcohol rapidly stimulated axoneme beating 40% above baseline at very low concentrations of alcohol (1 to 10 mM). This activation was specific to ethanol, required the synthesis of NO, the activation of soluble adenylyl cyclase (sAC), and the activation of both cAMP- and cGMP-dependent kinases (PKA and PKG), all of which were present in the isolated organelle preparation. Conclusions:, Alcohol rapidly and sequentially activates the eNOS,NO,GC,cGMP,PKG and sAC,cAMP, PKA dual signaling pathways in isolated airway axonemes. These findings indicate a direct effect of alcohol on airway cilia organelle function and fully recapitulate the alcohol-driven activation of cilia known to exist in vivo and in intact lung ciliated cells in vitro following brief moderate alcohol exposure. Furthermore, these findings indicate that airway cilia are exquisitely sensitive to the effects of alcohol and substantiate a key role for alcohol in the alterations of mucociliary clearance associated with even low levels of alcohol intake. We speculate that this same axoneme-based alcohol activation pathway is down regulated following long-term high alcohol exposure and that the isolated axoneme preparation provides an excellent model for studying the mechanism of alcohol-mediated cilia dysfunction. [source] Involvement of the contact phase and intrinsic pathway in herpes simplex virus-initiated plasma coagulationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2010E. S. GERSHOM Summary.,Background:,A hemostatic response to vascular injury is initiated by the extrinsic pathway of coagulation and amplified by the intrinsic pathway. We previously reported that purified herpes simplex virus type-1 (HSV1) has constitutive extrinsic pathway tissue factor (TF) and anionic phospholipid on its surface derived from the host cell, and can consequently bypass strict cellular control of coagulation. Objective:,The current work addresses the hypothesis that HSV1-induced plasma coagulation also involves intrinsic pathway, factor VIII (FVIII), and upstream contact activation pathway, factor XII (FXII). Results:,HSV1-initiated clotting was accelerated when purified FVIII was added to FVIII-deficient plasma and in normal plasma attenuated by an inhibitory anti-FVIII antibody (Ab). High HSV1 concentrations predictably reduced the effect of FVIII due to the availability of excess viral TF. To further define TF-independent clotting mechanisms initiated by HSV1, the extrinsic pathway was disabled using factor VII-deficient plasma. The intrinsic pathway is triggered by activation of FXII associated with surface-bound kallikrein, which subsequently activates factor XI. Here we found that an inhibitor of activated FXII, corn trypsin inhibitor, and anti-FXII, anti-kallikrein and anti-FXI Abs inhibited HSV1-initiated clotting. HSV1-enhanced activation of purified FXII was confirmed by Western blot, but required prekallikrein. Conclusion:,The current work shows that HSV1 can trigger and amplify coagulation through the contact phase and intrinsic pathway, and suggests an additional mechanism that may contribute to vascular pathology. [source] Epigallocatechin gallate (EGCG) attenuates high glucose-induced insulin signaling blockade in human hepG2 hepatoma cellsMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2008Chih-Li Lin Abstract Insulin resistance is the primary characteristic of type 2 diabetes which as a result of insulin signaling defects. It has been suggested that the tea polyphenol (,)-epigallocatechin-3-gallate (EGCG) displays some antidiabetic effects, but the mechanism for EGCG insulin-enhancing effects is incompletely understood. In the present study, the investigations of EGCG on insulin signaling are performed in insulin-responsive human HepG2 cells cotreated with high glucose. We found that the high glucose condition causes significant increasing Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1), leading to reduce insulin-stimulated phosphorylation of Akt. As the results, the insulin metabolic effects of glycogen synthesis and glucose uptake are inhibited by high glucose. However, the treatment of EGCG improves insulin-stimulated downsignaling by reducing IRS-1 Ser307 phosphorylation. Furthermore, we also demonstrated these EGCG effects are essential depends on the 5,-AMP-activated protein kinase (AMPK) activation. Together, our data suggest a putative link between high glucose and insulin resistance in HepG2 cells, and the EGCG treatment attenuates insulin signaling blockade by reducing IRS-1 Ser307 phosphorylation through the AMPK activation pathway. [source] Coupling of Protonation Switches During Rhodopsin Activation,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2007Reiner Vogel Recent studies of the activation mechanism of rhodopsin involving Fourier-transform infrared spectroscopy and a combination of chromophore modifications and site-directed mutagenesis reveal an allosteric coupling between two protonation switches. In particular, the ring and the 9-methyl group of the all- trans retinal chromophore serve to couple two proton-dependent activation steps: proton uptake by a cytoplasmic network between transmembrane (TM) helices 3 and 6 around the conserved ERY (Glu-Arg-Tyr) motif and disruption of a salt bridge between the retinal protonated Schiff base (PSB) and a protein counterion in the TM core of the receptor. Retinal analogs lacking the ring or 9-methyl group are only partial agonists,the conformational equilibrium between inactive Meta I and active Meta II photoproduct states is shifted to Meta I. An artificial pigment was engineered, in which the ring of retinal was removed and the PSB salt bridge was weakened by fluorination of C14 of the retinal polyene. These modifications abolished allosteric coupling of the proton switches and resulted in a stabilized Meta I state with a deprotonated Schiff base (Meta ISB). This state had a partial Meta II-like conformation due to disruption of the PSB salt bridge, but still lacked the cytoplasmic proton uptake reaction characteristic of the final transition to Meta II. As activation of native rhodopsin is known to involve deprotonation of the retinal Schiff base prior to formation of Meta II, this Meta ISB state may serve as a model for the structural characterization of a key transient species in the activation pathway of a prototypical G protein-coupled receptor. [source] Characterisation of new oligoglycosidic compounds in two Chinese medicinal herbsPHYTOCHEMICAL ANALYSIS, Issue 4 2002Sandra Apers Abstract A series of caffeic acid derivatives (3,5-dicaffeoyl-quinic acid, 3,4-dicaffeoyl-quinic acid, and 4,5-dicaffeoyl-quinic acid), and the new compound ,,3,4-trihydroxyphenethyl- O -[,-apiofuranosyl-(1,4)-,-rhamnopyranosyl-(1,3)]-(4- O -caffeoyl)-,-glucopyranoside (wedelosin), as well as three known flavonoid glycosides (quercetin 3- O -,-glucoside, kaempferol 3- O -,-apiosyl-(1-2)-,-glucoside, and astragalin or kaempferol 3- O -,-glucoside) were isolated from the Chinese medicinal herb Wedelia chinensis. Wedelosin showed an inhibitory activity on both the classical and the alternative activation pathway of the complement system. Another Chinese medicinal herb, Kyllinga brevifolia, yielded two known flavonoid glycosides [kaempferol 3- O -,-apiosyl-(1-2)-,-glucoside and isorhamnetin 3- O -,-apiosyl-(1-2)-,-glucoside], and a new quercetin triglycoside [quercetin 3- O -,-apiofuranosyl-(1,2)-,-glucopyranoside 7- O -,-rhamnopyranoside]. The latter compound showed a moderate anti-viral activity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Mechano-biology of skeletal muscle hypertrophy and regeneration: Possible mechanism of stretch-induced activation of resident myogenic stem cellsANIMAL SCIENCE JOURNAL, Issue 1 2010Ryuichi TATSUMI ABSTRACT In undamaged postnatal muscle fibers with normal contraction and relaxation activities, quiescent satellite cells of resident myogenic stem cells are interposed between the overlying external lamina and the sarcolemma of a subjacent mature muscle fiber. When muscle is injured, exercised, overused or mechanically stretched, these cells are activated to enter the cell proliferation cycle, divide, differentiate, and fuse with the adjacent muscle fiber, and are responsible for regeneration and work-induced hypertrophy of muscle fibers. Therefore, a mechanism must exist to translate mechanical changes in muscle tissue into chemical signals that can activate satellite cells. Recent studies of satellite cells or single muscle fibers in culture and in vivo demonstrated the essential role of hepatocyte growth factor (HGF) and nitric oxide (NO) radical in the activation pathway. These experiments have also reported that mechanically stretching satellite cells or living skeletal muscles triggers the activation by rapid release of HGF from its extracellular tethering and the subsequent presentation to the receptor c-met. HGF release has been shown to rely on calcium-calmodulin formation and NO radical production in satellite cells and/or muscle fibers in response to the mechanical perturbation, and depend on the subsequent up-regulation of matrix metalloproteinase (MMP) activity. These results indicate that the activation mechanism is a cascade of events including calcium ion influx, calcium-calmodulin formation, NO synthase activation, NO radical production, MMP activation, HGF release and binding to c-met. Better understanding of ,mechano-biology' on the satellite cell activation is essential for designing procedures that could enhance muscle growth and repair activities in meat-animal agriculture and also in neuromuscular disease and aging in humans. [source] Inhibition of NF-,B signaling by fasudil as a potential therapeutic strategy for rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 1 2010Hiroshi Okamoto Objective Rheumatoid arthritis (RA) is the most common systemic autoimmune disease and is characterized mainly by symmetric polyarticular joint disorders. The pathologic processes are mediated by a number of cytokines, chemokines, cell adhesion molecules, and matrix metalloproteinases. The expression of most of these molecules is controlled at the transcriptional level. In addition, activation of NF-,B is involved in RA pathogenesis. This study was performed to explore the role of a novel serine/threonine kinase inhibitor, fasudil, in the control of the NF-,B activation pathway and to investigate the therapeutic effects of fasudil on arthritis development in a rat model of RA. Methods Fibroblast-like synoviocytes (FLS) from RA patients and human endothelial cells (ECs) were established and maintained. To study the role of fasudil on cytokine expression, various cytokines expressed in the RA FLS and human ECs were measured by enzyme-linked immunosorbent assay following stimulation of the cells with interleukin-1, (IL-1,) in the presence of various concentrations of fasudil. The role of fasudil on NF-,B activation was studied using a reporter gene assay, Western blotting of I,B,, immunofluorescence analysis of the p65 subunit of NF-,B, and electrophoretic mobility shift assay. The in vivo effects of fasudil on arthritis were studied in a rat adjuvant-induced arthritis (AIA) model. Results Fasudil inhibited cytokine expression in RA FLS and human ECs and also inhibited the activation of ECs, in a dose-dependent manner. Fasudil inhibited IL-1,,induced activation of NF-,B independent of the inhibition of I,B, degradation and nuclear translocation of NF-,B, and inhibited IL-1,,induced DNA binding of NF-,B. Finally, in vivo, fasudil ameliorated arthritis in rats with AIA, without any adverse effects. Conclusion Serine/threonine kinase inhibitor fasudil inhibits the development of arthritis in a rat model of RA, and also inhibits the NF-,B signaling required for binding of NF-,B to specific DNA sequences through, for example, the phosphorylation of p65, suggesting that a specific target of fasudil might be a novel NF-,B kinase. Thus, fasudil serves as a novel strategy for the treatment of RA. [source] Differential mechanism of NF-,B inhibition by two glucocorticoid receptor modulators in rheumatoid arthritis synovial fibroblastsARTHRITIS & RHEUMATISM, Issue 11 2009Valerie Gossye Objective To investigate and compare the molecular mechanisms by which 2 glucocorticoid receptor (GR),activating compounds, dexamethasone (DEX) and Compound A (CpdA), interfere with the NF-,B activation pathway in rheumatoid arthritis (RA) synovial cells. Methods Quantitative polymerase chain reaction was performed to detect the tumor necrosis factor , (TNF,),induced cytokine gene expression of interleukin-1, (IL-1,) and to investigate the effects of DEX and CpdA in RA fibroblast-like synoviocytes (FLS) transfected with small interfering RNA (siRNA) against GR (siGR) compared with nontransfected cells. Immunofluorescence analysis was used to detect the subcellular distribution of NF-,B (p65) under the various treatment conditions, and active DNA-bound p65 was measured using a TransAM assay and by chromatin immunoprecipitation analysis of IL-1,. Signaling pathways were studied via Western blotting of siGR-transfected cells, compared with nontransfected and nontargeting siRNA,transfected control cells, to detect the regulation of phospho-IKK, I,B,, phospho-p38, phospho-ERK, and phospho-JNK. Results Both DEX and CpdA efficiently inhibited IL-1, gene expression in a GR-dependent manner. In addition, CpdA attenuated the TNF,-induced nuclear translocation and DNA binding of p65 in RA FLS, via the attenuation of IKK phosphorylation and subsequent I,B, degradation. CpdA also displayed profound effects on TNF,-induced MAPK activation. The effects of CpdA on TNF,-induced kinase activities occurred independently of the presence of GR. In sharp contrast, DEX did not affect TNF,-induced IKK phosphorylation, I,B, degradation, p65 nuclear translocation, or MAPK activation in RA FLS. Conclusion DEX and CpdA display a dissimilar molecular mechanism of interaction with the NF-,B activation pathway ex vivo. A dual pathway, partially dependent and partially independent of GR (nongenomic), may explain the gene-inhibitory effects of CpdA in RA FLS. [source] Activation of hepatocyte growth factor activator zymogen (pro-HGFA) by human kallikrein 1-related peptidasesFEBS JOURNAL, Issue 5 2008Shoichiro Mukai Hepatocyte growth factor activator (HGFA) is a serine protease and a potent activator of prohepatocyte growth factor/scatter factor (pro-HGF/SF), a multifunctional growth factor that is critically involved in tissue morphogenesis, regeneration, and tumor progression. HGFA circulates as a zymogen (pro-HGFA) and is activated in response to tissue injury. Although thrombin is considered to be an activator of pro-HGFA, alternative pro-HGFA activation pathways in tumor microenvironments remain to be identified. In this study, we examined the effects of kallikrein 1-related peptidases (KLKs), a family of extracellular serine proteases, on the activation of pro-HGFA. Among the KLKs examined (KLK2, KLK3, KLK4 and KLK5), we identified KLK4 and KLK5 as novel activators of pro-HGFA. Using N-terminal sequencing, the cleavage site was identified as the normal processing site, Arg407,Ile408. The activation of pro-HGFA by KLK5 required a negatively charged substance such as dextran sulfate, whereas KLK4 could process pro-HGFA without dextran sulfate. KLK5 showed more efficient pro-HGFA processing than KLK4, and was expressed in 50% (13/25) of the tumor cell lines examined. HGFA processed by these KLKs efficiently activated pro-HGF/SF, and led to cellular scattering and invasion in vitro. The activities of both KLK4 and KLK5 were strongly inhibited by HGFA inhibitor type 1, an integral membrane Kunitz-type serine protease inhibitor that inhibits HGFA and other pro-HGF/SF-activating proteases. These data suggest that KLK4 and KLK5 mediate HGFA-induced activation of pro-HGF/SF within tumor tissue, which may thereafter trigger a series of events leading to tumor progression via the MET receptor. [source] NRAMP1 (SLC11A1) gene polymorphisms that correlate with autoimmune versus infectious disease susceptibility in tuberculosis and rheumatoid arthritisINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 1 2009Ö. Ates Summary NRAMP1 gene has multiple pleiotropic effects on macrophage activation pathways. These pleiotropic effects may increase resistance to infections such as tuberculosis (TB), but may also lead to susceptibility of autoimmune diseases such as rheumatoid arthritis (RA). It has been hypothesized that allele 3 would be associated with autoimmune diseases, whereas allele 2 would be associated with infectious diseases, and genetic factors that enhanced survival in the epidemics of TB might have led to susceptibility for the development of RA. We analysed four NRAMP1 gene polymorphisms including 5, promoter (GT)n (rs34448891), INT4 (469 + 14G/C) (rs3731865), 3,UTR (1729 + 55del4) (rs17235416) and D543N (codon 543, Asp to Asn) (rs17235409) in 112 patients with TB, 98 patients with RA, 80 healthy controls for TB and 122 healthy controls for RA using ARMS-PCR and PCR-RFLP. We found a significant association between INT4 and RA (P = 0.004, odds ratio: 2.06, 95% CI: 1.24,3.41), but no significant differences between 5, promoter, D543N, 3,UTR polymorphisms and RA. There were no associations between NRAMP1 gene polymorphisms and TB. Similarly, no significant differences were observed between NRAMP1 polymorphisms and rheumatoid factor positivity and erosive disease in RA and localization of TB. INT4 polymorphism may be associated with RA in Turkish patients. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] Cover Picture: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010Catal. The cover picture, provided by David W.,C. MacMillan, shows a dual-catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ metal-to-ligand charge transfer (MLCT) excited state, eventually enabling single-electron transfer (SET) with an alkyl halide to furnish the electron-deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non-substituted aldehyde to form a stereochemically-defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source] CD56-expressing T cells that have features of senescence are expanded in rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 1 2007Joshua J. Michel Objective T cells deficient in CD28 expression have been implicated in the pathogenesis of rheumatoid arthritis (RA). Given that CD28-null T cells are functionally heterogeneous, we undertook this study to screen for novel receptors on these cells. Methods Seventy-two patients with RA (ages 35,84 years) and 53 healthy persons (32 young controls ages 19,34 years, 21 older controls ages 39,86 years) were recruited. Phenotypes and proliferative capacity of T cells from fresh leukocytes and of long-term cultures were monitored by flow cytometry. Lung biopsy specimens from patients with RA-associated interstitial pneumonitis (IP) were examined by immunohistochemistry. Receptor functionality was assessed by crosslinking bioassays. Results Chronic stimulation of CD28+ T cells in vitro yielded progenies that lacked CD28 but that gained CD56. Ex vivo analysis of leukocytes from patients with extraarticular RA showed a higher frequency of CD56+,CD28-null T cells than in patients with disease confined to the joints or in healthy controls. CD56+,CD28-null T cells had nil capacity for proliferation, consistent with cellular senescence. CD56+ T cells had skewed T cell receptor (TCR) ,/,-chain usage and restricted TCR third complementarity-determining region spectra. Histologic studies showed that CD56+ T cells were components of cellular infiltrates in RA-associated IP. CD56 crosslinking on T cells sufficiently induced cytokine production, although CD56/TCR coligation induced higher production levels. Conclusion Chronic activation of T cells induces counterregulation of CD28 and CD56 expression. The loss of CD28 is accompanied by the gain of CD56 that confers TCR-independent and TCR-dependent activation pathways. We propose that accumulation of CD56+ T cells in RA contributes to maladaptive immune responses and that CD56+ T cells are potential targets for therapy. [source] Long,term culture of multibacillary leprosy macrophages isolated from skin lesions: a new model to study Mycobacterium leprae,human cell interactionBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2007D.F. Moura Summary Background, Leprosy is characterized by a disease spectrum having two polar clinical forms dependent on the presence or not of cell-mediated immunity. In the tuberculoid forms, granuloma-activated macrophages kill Mycobacterium leprae in conjunction with a Th1 response while, in multibacillary (MB) lesions, M. leprae nonactivated macrophages infiltrate the nerves and internal organs together with a Th2 response. The functional properties and activation pathways of macrophages isolated from patients with MB leprosy remain only partially understood. Objectives, To establish an ex vivo methodology capable of evaluating the activation pathways, grade and fate of cultured macrophages isolated from MB lesions. Methods, Skin biopsies from patients with borderline tuberculoid, bordeline lepromatous and lepromatous leprosy (LL) were characterized by immunohistochemistry and transcriptional analysis. To isolate inflammatory cells, a portion of the samples was submitted to enzymatic digestion. These same cells, maintained in culture for a minimum 7-day period, were characterized morphologically and via flow cytometry at different culture time points. Cytokine [interferon (IFN)-,, tumour necrosis factor (TNF)-, and interleukin (IL)-10] mRNA levels were quantified by real-time polymerase chain reaction and protein secretion in the culture supernatants was measured by enzyme-linked immunosorbent assay and the nitric oxide levels by Griess reagent. Results, RNA expression in tuberculoid and MB lesions showed the profile expected of characteristic Th1 and Th2 responses, respectively. The inflammatory cells in all biopsies were successfully isolated. Although the number of cells varied between biopsies, it was highest in LL biopsies. The frequency of isolated CD14+ and CD3+ cells measured by flow cytometry correlated with the percentages of macrophages and lymphocytes in the lesions. Throughout the culture period, CD68+ macrophages showed morphological changes. A progressive increase in cell number and reduction of infected cells were perceptible in the cultures. In contrast to the biopsies, TNF-,, IFN-, and IL-10 expression in the tuberculoid and MB leprosy cells in 24-h culture and the cytokine levels in the supernatants did not differ significantly. During the culture period, cytokine expression in the MB cells progressively declined, whereas, from days 1 to 7, nitrite levels progressively increased. After day 40, the remaining macrophages were able to ingest fluorescein isothiocyanate-labelled M. leprae. These data need to be confirmed. Conclusions, This study confirmed the feasibility of obtaining ex vivo macrophages from leprosy lesions and keeping them in long-term culture. This procedure may open new pathways to studying the interaction between M. leprae and human macrophages, which might, in turn, lead to the development of therapeutic tools capable of overcoming the specific anergy found in patients with MB leprosy. [source] Modulation of caspases and their non-apoptotic functions by Legionella pneumophilaCELLULAR MICROBIOLOGY, Issue 2 2010Amal O. Amer Summary Legionella pneumophila has become a model system to decipher the non-apoptotic functions of caspases and their role in immunity. In permissive cells, the L. pneumophila -containing vacuole evades endosomal traffic and is remodelled by the endoplasmic reticulum. Evasion of the endosomes is mediated by the Dot/Icm type IV secretion system. Upon L. pneumophila infection of genetically restrictive cells such as wild-type (WT) C57Bl/6J murine macrophages, flagellin is sensed by the NOD-like receptor Nlrc4 leading to caspase-1 activation by the inflammasome complex. Then, caspase-7 is activated downstream of the Nlrc4 inflammasome, promoting non-apoptotic functions such as L. pneumophila -containing phagosome maturation and bacterial degradation. Interestingly, caspase-3 is activated in permissive cells during early stages of infection. However, caspase-3 activation does not lead to apoptosis until late stages of infection because it is associated with potent Dot/Icm-mediated anti-apoptotic stimuli that render the infected cells resistant to external apoptotic inducers. Therefore, the role of caspase-1 and non-apoptotic functions of executioner caspases are temporally and spatially modulated during infection by L. pneumophila, which determine permissiveness to intracellular bacterial proliferation. This review will examine the novel activation pathways of caspases by L. pneumophila and discuss their role in genetic restriction and permissiveness to infection. [source] Mannose binding lectin gene polymorphisms and asthmaCLINICAL & EXPERIMENTAL ALLERGY, Issue 9 2007X. Wang Summary Background Bronchial asthma is a chronic inflammatory disorder of the airways. Recently, it has been suggested that complement plays significant roles in asthma. Mannose-binding lectin (MBL) is one of the key molecules in complement activation pathways that are associated with several infectious and immune disorders. Subjects and method To investigate whether MBL plays roles in asthma, we analysed MBL2 polymorphisms (allele B, H/L and Y/X) and plasma MBL levels in a Japanese adult population including 232 healthy controls and 579 asthmatics. Results Although there was linkage disequilibrium among the three polymorphisms, each polymorphism significantly affects serum MBL levels independently. However, there were no significant differences between asthmatics and controls in MBL2 genotype distribution and in MBL concentrations [1.47±0.07(SE) mg/L for asthmatics and 1.66±0.14 mg/L for controls, P=0.2]. MBL levels and genotype have no significant relationship with serum IgE, pulmonary functions, and the severity of asthma. Conclusion Although plasma MBL levels depend on the MBL2 polymorphisms, these polymorphisms and plasma MBL levels are not associated with the asthma phenotype. [source] | ||||||||||||||||