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Critical Role (critical + role)
Kinds of Critical Role Selected AbstractsCritical Role of Reactive Oxygen Species and Mitochondrial Permeability Transition in Microcystin-Induced Rapid Apoptosis in Rat HepatocytesHEPATOLOGY, Issue 3 2000Wen-Xing Ding Microcystin-LR (M-LR) is a specific hepatotoxin. At present, the exact toxic mechanism of its action remains unclear though apoptosis is believed to be involved. This study was designed to investigate the role of reactive oxygen species (ROS) and mitochondrial permeability transition (MPT) in the M-LR,induced apoptotic process. Morphologic changes such as cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and nuclear condensation suggest that M-LR causes rapid apoptosis in hepatocytes. Confocal microscopy revealed that M-LR exposure led to the onset of MPT and mitochondrial depolarization, evidenced by (1) redistribution of calcein fluorescence from cytosol to mitochondria, and (2) loss of mitochondrial tetramethyrhodamine methyl ester (TMRM) fluorescence; both occurred before apoptosis. Moreover, there was a significant and rapid increase of ROS level before the onset of MPT and loss of MMP, indicating a critical role of ROS in M-LR,induced apoptosis. Deferoxamine (DFO), an iron chelator, prevented the increase of ROS production, delayed the onset of MPT, and, subsequently, cell death. In addition, a specific MPT inhibitor, cyclosporin A (CsA), blocked the M-LR,induced ROS formation, onset of MPT, and mitochondrial depolarization as well as cell death. Thus, we conclude that the M-LR,induced ROS formation leads to the onset of MPT and apoptosis. [source] Critical Role of Inferior Vena Caval Filter Placement After Pulmonary EmbolectomyJOURNAL OF CARDIAC SURGERY, Issue 3 2005Peter Rosenberger M.D. Postoperative placement of an inferior vena caval filter (IVCF) may prevent recurrent PE. We present a patient who underwent pulmonary embolectomy in whom postoperative placement of an IVCF was postponed due to hemodynamic instability and severe hemorrhage. Recurrent PE was recognized 12 hours after the initial surgery, and required reoperative pulmonary embolectomy. This report documents that recurrent PE can occur early after pulmonary embolectomy even in the presence of coagulopathy. Therefore, concurrent IVCF placement should be considered during or immediately after pulmonary embolectomy to prevent recurrent pulmonary embolism. [source] Critical Role for IL-6 in Hypertrophy and Fibrosis in Chronic Cardiac Allograft RejectionAMERICAN JOURNAL OF TRANSPLANTATION, Issue 8 2009J. A. Diaz Chronic cardiac allograft rejection is the major barrier to long term graft survival. There is currently no effective treatment for chronic rejection except re-transplantation. Though neointimal development, fibrosis, and progressive deterioration of graft function are hallmarks of chronic rejection, the immunologic mechanisms driving this process are poorly understood. These experiments tested a functional role for IL-6 in chronic rejection by utilizing serial echocardiography to assess the progression of chronic rejection in vascularized mouse cardiac allografts. Cardiac allografts in mice transiently depleted of CD4+ cells that develop chronic rejection were compared with those receiving anti-CD40L therapy that do not develop chronic rejection. Echocardiography revealed the development of hypertrophy in grafts undergoing chronic rejection. Histologic analysis confirmed hypertrophy that coincided with graft fibrosis and elevated intragraft expression of IL-6. To elucidate the role of IL-6 in chronic rejection, cardiac allograft recipients depleted of CD4+ cells were treated with neutralizing anti-IL-6 mAb. IL-6 neutralization ameliorated cardiomyocyte hypertrophy, graft fibrosis, and prevented deterioration of graft contractility associated with chronic rejection. These observations reveal a new paradigm in which IL-6 drives development of pathologic hypertrophy and fibrosis in chronic cardiac allograft rejection and suggest that IL-6 could be a therapeutic target to prevent this disease. [source] Providing a Critical Role,ACTA NEUROPSYCHIATRICA, Issue 4 2010Professor Gin S. Malhi No abstract is available for this article. [source] The Transcriptional Coactivator p300 Plays a Critical Role in the Hypertrophic and Protective Pathways Induced by Phenylephrine in Cardiac Cells but Is Specific to the Hypertrophic Effect of UrocortinCHEMBIOCHEM, Issue 1 2005Sean M. Davidson Dr. Abstract Anacardic acid is an alkylsalicylic acid obtained from cashew-nut-shell liquid, and is a potent inhibitor of p300 histone acetyl-transferase (HAT) activity. We have used anacardic acid to prevent the induction of hypertrophy in isolated neonatal rat cardiomyocytes. Hypertrophy was detected as an increase in cell size, the rearrangement of sarcomeres into a striated pattern, and the induction of embryonic genes ,-MHC and ANF. p300 inhibition was equally effective at preventing hypertrophy whether it was induced by treatment with the ,1-adrenergic agonist, phenylephrine, or by treatment with urocortin, a member of the corticotrophin-releasing-factor family, which stimulates specific G protein-coupled receptors. Spiruchostatin A is a natural-product inhibitor of histone deacetylases (HDAC) similar to the depsipeptide FK228 molecule. We have recently synthesized spiruchostatin A and now show that, although HDACs act in opposition to HATs, spiruchostatin A has the same effect as anacardic acid, that is, it prevents the induction of hypertrophy in response to phenylephrine or urocortin. Pretreatment with either phenylephrine or urocortin reduced the extent of death observed after the exposure of isolated cardiomyocytes to simulated ischaemia and reoxygenation. Inhibition of p300 or HDAC activity eliminated the protection conferred by phenylephrine; however, it did not affect the protection conferred by urocortin. Therefore, it might eventually be possible to use chemical inhibitors such as these in a therapeutic setting to dissociate the protective effect and hypertrophic effect of urocortin, enhancing the survival of cardiomyocytes exposed to transient ischemia, while inhibiting the hypertrophic pathway that would otherwise be induced concurrently. [source] Critical Role of Water Content in the Formation and Reactivity of Uranium, Neptunium, and Plutonium Iodates under Hydrothermal Conditions: Implications for the Oxidative Dissolution of Spent Nuclear Fuel.CHEMINFORM, Issue 30 2007Travis H. Bray Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of Muscothiazoles A and B: Critical Role of Methyl Group Substitution in RCM-Based Syntheses of Macrocycles.CHEMINFORM, Issue 49 2003Aurelien G. J. Commeureuc Abstract For Abstract see ChemInform Abstract in Full Text. [source] Critical role for retinol in the generation/differentiation of angioblasts required for embryonic blood vessel formation,DEVELOPMENTAL DYNAMICS, Issue 4 2004Amanda C. LaRue Abstract Numerous studies demonstrate that vitamin A (retinol) deficiency causes abnormal cardiovascular morphogenesis. We evaluated the impact of retinol deficiency on the regulation of the numbers of endothelial cells and angioblasts (endothelial progenitors) produced during embryonic quail development. At the one-somite stage, there were no discernible differences in the mean number of endothelial cells or angioblasts in normal and retinol-deficient embryos. However, retinol-deficient embryos at the three-somite stage had an increase in the mean number of endothelial cells but no difference in the mean number of angioblasts. By contrast, retinol-deficient embryos at the five-somite stage have 61% of the normal number of endothelial cells and 12% of the normal number of angioblasts. Similarly, retinol-deficient embryos at the 10-somite stage had 71% and 60% of normal numbers of endothelial cells in capillary-like networks and the sinuses venosus, respectively. Furthermore, we show that retinol deficiency did not elicit a global reduction in mesodermal cell numbers but was specific to cells of the endothelial lineage. Taken together, our findings suggest that vascular abnormalities observed under conditions of retinol deficiency are due to reduction in the number of angioblasts and consequently an insufficiency in the number of endothelial cells required to build complex vascular networks. Developmental Dynamics 230:666,674, 2004. © 2004 Wiley-Liss, Inc. [source] Critical role of amygdala in flavor but not taste preference learning in ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2005Khalid Touzani Abstract The role of the amygdala (AMY) in learning to associate complex flavor (taste + odor cues) with the oral and post-oral properties of nutrients was examined. Rats with excitotoxic lesions of the basolateral AMY learned to prefer flavors paired with intragastric (IG) infusions of maltodextrin or corn oil (Experiment 1), although the preference was slightly attenuated. However, rats with large AMY lesions failed to develop a preference for flavors paired with IG infusions of the same nutrients (Experiments 2 and 4) but were able to learn a preference for a taste mixture paired with IG maltodextrin infusions (Experiment 3). The rats with large AMY lesions also did not acquire a preference for a flavor cue paired with the sweet taste of fructose (Experiment 5). Collectively, these data provide evidence that AMY is essential for flavor- but not taste-nutrient preference learning. [source] Critical role of C/EBP, and C/EBP, factors in the stimulation of the cyclooxygenase-2 gene transcription by interleukin-1, in articular chondrocytesFEBS JOURNAL, Issue 23 2000Béatrice Thomas The activity of the [,831; +103] promoter of the human cyclooxygenase-2 gene in cultured rabbit chondrocytes is stimulated 2.9 ± 0.3-fold by interleukin-1, and this stimulation depends on [,132; ,124] C/EBP binding-and [,223; ,214] NF-,B binding-sites. The C/EBP, and C/EBP, factors bind to the [,132; ,124] sequence. The [,61; ,53] sequence is also recognized by C/EBP, and C/EBP, as well as USF. Mutation of the whole [,61; ,53] sequence abolished the stimulation of transcription but single mutations of the C/EBP or USF site did not alter the activity of the promoter, suggesting that the factors bound to the proximal [,61; ,53] sequence interact with different members of the general transcription machinery. The [,223; ,214] site binds only the p50/p50 homodimer and a non-rel-related protein, but not the transcriptionally active heterodimer p50/p65. The p50/p50 homodimer could interact with the C/EBP family members bound to the [,132; ,124] sequence for full stimulation of the COX-2 transcription by interleukin-1, in chondrocytes. By contrast, the [,448; ,449] sequence binds with a low affinity both the p50/p50 homodimeric and p50/p65 heterodimeric forms of NF-,B but has no role in the regulation of the human COX-2 promoter in chondrocytes. [source] Critical role of acidic sphingomyelinase in murine hepatic ischemia-reperfusion injury,HEPATOLOGY, Issue 3 2006Laura Llacuna The molecular mechanisms of hepatic ischemia/reperfusion (I/R) damage are incompletely understood. We investigated the role of ceramide in a murine model of warm hepatic I/R injury. This sphingolipid induces cell death and participates in tumor necrosis factor (TNF) signaling. Hepatic ceramide levels transiently increased after the reperfusion phase of the ischemic liver in mice, because of an early activation of acidic sphingomyelinase (ASMase) followed by acid ceramidase stimulation. In vivo administration of an ASMase inhibitor, imipramine, or ASMase knockdown by siRNA decreased ceramide generation during I/R, and attenuated serum ALT levels, hepatocellular necrosis, cytochrome c release, and caspase-3 activation. ASMase-induced ceramide generation activated JNK resulting in BimL phosphorylation and translocation to mitochondria, as the inhibition of ASMase by imipramine prevented these events. In contrast, blockade of ceramide catabolism by N-oleyolethanolamine (NOE), a ceramidase inhibitor, enhanced ceramide levels and potentiated I/R injury compared with vehicle-treated mice. Pentoxifylline treatment prevented TNF upregulation and ASMase activation. Furthermore, 9 of 11 mice treated with imipramine survived 7 days after total liver ischemia, compared with 4 of 12 vehicle-treated mice, whereas 8 of 8 NOE-treated mice died within 2 days of total liver ischemia. In conclusion, ceramide generated from ASMase plays a key role in I/R-induced liver damage, and its modulation may be of therapeutic relevance. (HEPATOLOGY 2006.) [source] Critical role of NFATc1 in periapical lesionsINTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2010C. Zhang Zhang C, Yang L, Peng B. Critical role of NFATc1 in periapical lesions. International Endodontic Journal, 43, 109,114, 2010. Abstract Aim, To observe NFATc1 expression in experimental periapical lesions in rats. Methodology, Apical periodontitis was induced in Wistar rats by occlusal pulp exposure in mandibular first molar teeth. After exposure, 30 rats were killed on days 0, 7, 14, 21 and 28. The jaws that contained the first molar were removed and prepared for histological examination, immunohistochemistry and enzyme histochemistry. Results, From day 0 to day 28, the areas of periapical bone loss and the number of NFATc1-positive cells increased, peaking on day 28. The number of TRAP-positive cells increased substantially from day 0 to day 14 and then gradually decreased from day 14 to day 28. Conclusions, NFATc1 was detected and possibly involved in the inflammatory response and bone resorption of periapical tissues, as well as being associated with periapical lesion pathogenesis. [source] Critical role of ADP interaction with P2Y12 receptor in the maintenance of ,IIb,3 activation: association with Rap1B activationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2006T. KAMAE Summary.,Objective:,Platelet integrin ,IIb,3 plays a crucial role in platelet aggregation, and the affinity of ,IIb,3 for fibrinogen is dynamically regulated. Employing modified ligand-binding assays, we analyzed the mechanism by which ,IIb,3 maintains its high-affinity state. Methods and results:,Washed platelets adjusted to 50 × 103 ,L,1 were stimulated with 0.2 U mL,1 thrombin or 5 ,m U46619 under static conditions. After the completion of ,IIb,3 activation and granule secretion, different kinds of antagonists were added to the activated platelets. The activated ,IIb,3 was then detected by fluorescein isothiocyanate (FITC)-labeled PAC1. The addition of 1 ,m AR-C69931MX (a P2Y12 antagonist) or 1 mm A3P5P (a P2Y1 antagonist) disrupted the sustained ,IIb,3 activation by ,92% and ,38%, respectively, without inhibiting CD62P or CD63 expression. Dilution of the platelet preparation to 500 ,L,1 also disrupted the sustained ,IIb,3 activation, and the disruption by such dilution was abrogated by the addition of exogenous adenosine 5,-diphosphate (ADP) in a dose-dependent fashion. The amounts of ADP released from activated platelets determined by high-performance liquid chromatography were compatible with the amounts of exogenous ADP required for the restoration. We next examined the effects of antagonists on protein kinase C (PKC) and Rap1B activation induced by 0.2 U mL,1 thrombin. Thrombin induced long-lasting PKC and Rap1B activation. AR-C69931MX markedly inhibited Rap1B activation without inhibiting PKC activation. Conclusions:,Our data indicate that the continuous interaction between released ADP and P2Y12 is critical for the maintenance of ,IIb,3 activation. [source] Critical role of the vascular endothelial cell in health and disease: a review articleJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 2 2004Todd C. Duffy DVM Abstract Objective: To review the human and veterinary literature on the role of the vascular endothelial cell in health, as well as during hypoxic and inflammatory disease states. Data sources: Data from human and veterinary literature were reviewed through a Pubmed search and a manual search of the references listed in articles covering some aspect of vascular endothelial cell function. Human data synthesis: The development of techniques that allow the maintenance and growth of endothelial cells in culture has produced an explosion of new research in the area of endothelial cell physiology. This plethora of data has revealed the critical role that vascular endothelial cells play in both health and disease states. Interspecies variations can occur with respect to the vascular endothelial cell physiology and its response to pathologic conditions. Veterinary data synthesis: There is a paucity of information regarding the role of the vascular endothelial cell in health or disease of small animals. Many human studies use species cared for by veterinarians, providing information that may be applied to small animals and that may be used to construct future studies. Conclusion: An organ system itself, the vascular endothelium is an essential component of all organs in the body. The endothelial cell lining functions to maintain selective permeability between the blood and the tissue it supplies, regulate vascular tone, sustain blood fluidity through regulation of coagulation, and modulate interaction of leukocytes with the interstitium and inflammatory reactions. During disease states, the endothelial cell functions locally to limit the boundaries of the disease process. If these functions are not controlled, they can become a part of the pathogenic process, contributing to blood stasis and thrombosis, potentiation of local inflammation and interstitial edema formation, subsequent tissue hypoxia, and multiple organ dysfunction. Pharmacological investigations targeting the modulation of endothelial function during disease states have not yet advanced treatment protocols. Since all critically ill animals are at risk for some degree of endothelial cell dysfunction, treatment regimens should focus on promoting capillary blood flow and tissue oxygen delivery. [source] Critical role of ribavirin for the achievement of early virological response to HCV therapy in HCV/HIV-coinfected patientsJOURNAL OF VIRAL HEPATITIS, Issue 6 2007B. Ramos Summary., The response to hepatitis C virus (HCV) therapy seems to be lower in HCV/HIV-coinfected patients than in HCV-monoinfected individuals. Given that most pivotal trials conducted in coinfected patients have used the combination of pegylated interferon (pegIFN) along with fixed low doses (800 mg/day) of ribavirin (RBV), it is unclear whether HIV itself and/or suboptimal RBV exposure could explain this poorer outcome. Two well-defined end points of early virological response were evaluated in Peginterferon Ribavirina España Coinfección (PRESCO), a multicentre trial in which the combination of pegIFN plus RBV (1000 mg if body weight <75 kg and 1200 mg if >75 kg) was prescribed to coinfected patients. For comparisons, we used unpublished data from early kinetics in two other large trials, one performed in HIV-negative patients [Pegasys International Study Group (PISG)] in which RBV 1000,1200 mg/day was used and another [AIDS Pegasys Ribavirin Coinfection Trial (APRICOT)] in which HIV-positive patients received fixed low RBV doses (800 mg/day). A total of 348 HCV/HIV-coinfected patients from the PRESCO trial were analysed as well as all patients treated with pegIFN plus RBV, who completed 12 weeks of therapy in the comparative studies (435 in PISG and 268 in APRICOT). Negative serum HCV-RNA at week 4 (which has the highest positive predictive value of sustained virological response, SVR) was attained in 33.3%, 31.2% and 13% of treated patients with HCV genotype 1, respectively, in PRESCO, PISG and APRICOT. For HCV genotypes 2/3, responses were 83.7%, 84.2% and 37%, respectively. A decline lower than 2 log10 at week 12 (which has the highest negative predictive value of SVR) was seen in 25.5%, 19.5% and 37% of HCV genotype-1-infected patients, and in 2.1%, 2.9% and 12% of genotypes-2/3-infected patients, respectively. Prescription of high RBV doses enhances the early virological response to HCV therapy in HCV/HIV-coinfected patients, with results approaching those seen in HCV-monoinfected patients. [source] Distal enhancer of the mouse FGF-4 gene and its human counterpart exhibit differential activity: Critical role of a GT boxMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 3 2005Brian Boer Abstract Previous studies have shown that there is a strict requirement for fibroblast growth factor-4 (FGF-4) during mammalian embryogenesis, and that FGF-4 expression in embryonic stem (ES) cells and embryonal carcinoma (EC) cells are controlled by a powerful downstream distal enhancer. More recently, mouse ES cells were shown to express significantly more FGF-4 mRNA than human ES cells. In the work reported here, we demonstrate that mouse EC cells also express far more FGF-4 mRNA than human EC cells. Using a panel of FGF-4 promoter/reporter gene constructs, we demonstrate that the enhancer of the mouse FGF-4 gene is approximately tenfold more active than its human counterpart. Moreover, we demonstrate that the critical difference between the mouse and the human FGF-4 enhancer is a 4 bp difference in the sequence of an essential GT box. Importantly, we demonstrate that changing 4 bp in the human enhancer to match the sequence of the mouse GT box elevates the activity of the human FGF-4 enhancer to the same level as that of the mouse enhancer. We extended these studies by examining the roles of Sp1 and Sp3 in FGF-4 expression. Although we demonstrate that Sp3, but not Sp1, can activate the FGF-4 promoter when artificially tethered to the FGF-4 enhancer, we show that Sp3 is not essential for expression of FGF-4 mRNA in mouse ES cells. Finally, our studies with human EC cells suggest that the factor responsible for mediating the effect of the mouse GT box is unlikely to be Sp1 or Sp3, and this factor is either not expressed in human EC cells or it is not sufficiently active in these cells. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Development of an ex vivo cellular model of rheumatoid arthritis: Critical role of cd14-positive monocyte/macrophages in the development of pannus tissueARTHRITIS & RHEUMATISM, Issue 9 2007Toshiko Nozaki Objective To establish an ex vivo cellular model of pannus, the aberrant overgrowth of human synovial tissue (ST). Methods Inflammatory cells that infiltrated pannus tissue from patients with rheumatoid arthritis (RA) were collected without enzyme digestion, and designated as ST-derived inflammatory cells. Single-cell suspensions of ST-derived inflammatory cells were cultured in medium alone. Levels of cytokines produced in culture supernatants were measured using enzyme-linked immunosorbent assay kits. ST-derived inflammatory cells were transferred into the joints of immunodeficient mice to explore whether these cells could develop pannus. CD14 and CD2 cells were depleted by negative selection. Results Culture of ST-derived inflammatory cells from 92 of 111 patients with RA resulted in spontaneous reconstruction of inflammatory tissue in vitro within 4 weeks. Ex vivo tissue contained fibroblasts, macrophages, T cells, and tartrate-resistant acid phosphatase,positive multinucleated cells. On calcium phosphate,coated slides, ST-derived inflammatory cell cultures showed numerous resorption pits. ST-derived inflammatory cell cultures continuously produced matrix metalloproteinase 9 and proinflammatory cytokines associated with osteoclastogenesis, such as tumor necrosis factor ,, interleukin-8, and macrophage colony-stimulating factor. More importantly, transferring ST-derived inflammatory cells into the joints of immunodeficient mice resulted in the development of pannus tissue and erosive joint lesions. Both in vitro development and in vivo development of pannus tissue by ST-derived inflammatory cells were inhibited by depleting CD14-positive, but not CD2-positive, cells from ST-derived inflammatory cells. Conclusion These findings suggest that overgrowth of inflammatory cells from human rheumatoid synovium simulates the development of pannus. This may prove informative in the screening of potential antirheumatic drugs. [source] Critical role of Nitric Oxide on Nicotine-Induced Hyperactivation of Dopaminergic Nigrostriatal System: Electrophysiological and Neurochemical evidence in RatsCNS: NEUROSCIENCE AND THERAPEUTICS, Issue 3 2010Vincenzo Di Matteo Nicotine, the main psychoactive ingredient in tobacco, stimulates dopamine (DA) function, increasing DA neuronal activity and DA release. DA is involved in both motor control and in the rewarding and reinforcing effects of nicotine; however, the complete understanding of its molecular mechanisms is yet to be attained. Substantial evidence indicates that the reinforcing properties of drugs of abuse, including nicotine, can be affected by the nitric oxide (NO) system, which may act by modulating central dopaminergic function. In this study, using single cell recordings in vivo coupled with microiontophoresis and microdialysis in freely moving animals, the role of NO signaling on the hyperactivation elicited by nicotine of the nigrostriatal system was investigated in rats. Nicotine induced a dose-dependent increase of the firing activity of the substantia nigra pars compacta (SNc) DA neurons and DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release in the striatum. Pharmacological manipulation of the NO system did not produce any change under basal condition in terms of neuronal discharge and DA release. In contrast, pretreatments with two NO synthase (NOS) inhibitors, N-,-nitro- l -arginine methyl ester (l -NAME) and 7-nitroindazole (7-NI) were both capable of blocking the nicotine-induced increase of SNc DA neuron activity and DA striatal levels. The effects of nicotine in l -NAME and 7-NI-pretreated rats were partially restored when rats were pretreated with the NO donor molsidomine. These results further support the evidence of an important role played by NO on modulation of dopaminergic function and drug addiction, thus revealing new pharmacological possibilities in the treatment of nicotine dependence and other DA dysfunctions. [source] Critical roles of LGN/GPSM2 phosphorylation by PBK/TOPK in cell division of breast cancer cellsGENES, CHROMOSOMES AND CANCER, Issue 10 2010Chikako Fukukawa To investigate the molecular mechanism of mammary carcinogenesis and identify novel molecular targets for breast cancer therapy, we analyzed genome-wide gene expression profiles of 81 clinical breast cancer samples. Here, we report the critical role of LGN/GPSM2 (Leu-Gly-Asn repeat-enriched protein/G-protein signaling modulator 2) in the growth of breast cancer cells. Semiquantitative RT-PCR and Northern blot analyses confirmed upregulation of LGN/GPSM2 in a large proportion of breast cancers. Immunocytochemical staining identified LGN/GPSM2 at the spindle in cells at metaphase, and at midzone and midbody in cytokinetic cells. Western blot analysis indicated the highest expression and the phosphorylated form of LGN/GPSM2 protein in G2/M phase. Treatment with small-interfering RNAs (siRNAs) targeting LGN/GPSM2 caused incompletion of cell division and resulted in significant growth suppression of breast cancer cells. We found that the 450th threonine (Thr450) of LGN/GPSM2 was phosphorylated by the serine/threonine kinase PBK/TOPK during mitosis. Overexpression of LGN/GPSM2-T450A in which Thr450 was substituted with alanine induced growth suppression and aberrant chromosomal segregation. These findings imply an important role of LGN/GPSM2 in cell division of breast cancer cells and suggest that the PBK/TOPK-LGN/GPSM2 pathway might be a promising molecular target for treatment of breast cancer. © 2010 Wiley-Liss, Inc. [source] Critical roles for thrombin in acute and chronic inflammationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2009D. CHEN Summary., Thrombin can amplify inflammation induced by other stimuli, either through ischemia (consequent upon thrombosis), indirectly through generation of downstream mediators such as activated protein C, or directly via signals through protease activated receptors (PAR). This paper will summarize recent data from our laboratory indicating that thrombin is required to initiate CCR2-dependent leukocyte recruitment and that it is the principal determinant of the outcome after vascular injury, via PAR-1 activation of a distinct subset of smooth muscle cell progenitors. In both, tissue factor (TF) initiates thrombin generation and the thrombin acts locally, exemplifying that the initiation phase can generate autocrine or paracrine signalling molecules. Thrombin is an important constituent of innate immunity, able to amplify and modify responses to invading pathogens or tissue damage. With novel anti-thrombin therapeutics and agents to target PAR, a new understanding of the importance of thrombin may allow the development of innovative anti-inflammatory strategies. [source] Apolipoprotein(a) inhibits the conversion of Glu-plasminogen to Lys-plasminogen: a novel mechanism for lipoprotein(a)-mediated inhibition of plasminogen activationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 12 2008N. T. FERIC Summary.,Background:,Elevated plasma concentrations of lipoprotein(a) [Lp(a)] are associated with an increased risk for thrombotic disorders. Lp(a) is a unique lipoprotein consisting of a low-density lipoprotein-like moiety covalently linked to apolipoprotein(a) [apo(a)], a homologue of the fibrinolytic proenzyme plasminogen. Several in vitro and in vivo studies have shown that Lp(a)/apo(a) can inhibit tissue-type plasminogen activator-mediated plasminogen activation on fibrin surfaces, although the mechanism of inhibition by apo(a) remains controversial. Essential to fibrin clot lysis are a number of plasmin-dependent positive feedback reactions that enhance the efficiency of plasminogen activation, including the plasmin-mediated conversion of Glu-plasminogen to Lys-plasminogen. Objective:,Using acid,urea gel electrophoresis to resolve the two forms of radiolabeled plasminogen, we determined whether apo(a) is able to inhibit Glu-plasminogen to Lys-plasminogen conversion. Methods:,The assays were performed in the absence or presence of different recombinant apo(a) species, including point mutants, deletion mutants and variants that represent greater than 90% of the known apo(a) isoform sizes. Results:,Apo(a) substantially suppressed Glu-plasminogen conversion. Critical roles were identified for the kringle IV types 5,9 and kringle V; contributory roles for sequences within the amino-terminal half of the molecule were also observed. Additionally, with the exception of the smallest naturally-occurring isoform of apo(a), isoform size was found not to contribute to the inhibitory capacity of apo(a). Conclusion:,These findings underscore a novel contribution to the understanding of Lp(a)/apo(a)-mediated inhibition of plasminogen activation: the ability of the apo(a) component of Lp(a) to inhibit the key positive feedback step of plasmin-mediated Glu-plasminogen to Lys-plasminogen conversion. [source] Critical roles of VEGF-C-VEGF receptor 3 in reconnection of the collecting lymph vessels in miceMICROCIRCULATION, Issue 7 2008FUMITAKA IKOMI M.D, Ph.D ABSTRACT Molecular mechanisms of reconnection of collecting lymph vessels were analyzed by using murine popliteal prenodal lymph vessels. At 1 and 2 weeks after being divided by cutting the lymph vessel, lymphatic reconnection was frequently observed accompanied by mesh-like lymphatic channels. Electron microscopic study also showed a monolayer of endothelial cells in the newly developed lymph vessels. Smooth muscle markers were immunofluorescently demonstrated in the wall of the new vessels. At 1 week after the procedure of cutting, augmented expressions of VEGF receptors 1, 2 and 3 were found immunohistochemically at the site of the reconnected lymph vessels. The expression of mRNA for VEGF receptor 3 was enhanced at 5 days and 1 week in small pieces of the tissues containing the reconnected lymph vessels, compared with that in the corresponding tissues obtained with sham operated ones. The administration of VEGF-C at the cutting site of the collecting lymph vessel significantly increased the rate of the reconnected lymph vessels, whereas additional treatment with Flt4/Fc chimera protein significantly reduced the rate of the reconnected ones. These results suggest that activation of VEGF-C-VEGF receptor 3 has critical roles in reconnection of the collecting lymph vessels in adult mice. [source] Craniorachischisis and Heterotaxia with Heart Disease in Twins: Link or Change Nature?CONGENITAL HEART DISEASE, Issue 5 2010Sebastiano Bianca MD ABSTRACT Craniorachischisis is a rare neural tube defect in which both acrania and a complete schisis of the vertebral column are present. Heterotaxy results from failure to establish normal left,right asymmetry during embryonic development and is characterized by a variable group of congenital anomalies that include complex cardiac malformations and situs inversus or situs ambiguous. We report a diamniotic twin pregnancy with two malformed fetuses affected one by craniorachischisis and the other by heterotaxya with paired right-sided viscera, asplenia, and complex congenital heart disease. The occurrence of severe congenital anomalies in both members of the twin pair implies a strong influence of genetic factors. At present, the genetic basis determining the different phenotypes observed in our twins is unknown. Our case with the simultaneous presence of both midline and laterality defects in twins supports the hypothesis that the midline plays a critical role in establishing left,right asymmetry in the body and that a mutation in a gene responsible for both heterotaxy and midline defects may be strongly supposed. [source] Normoxic destabilization of ATF-4 depends on proteasomal degradationACTA PHYSIOLOGICA, Issue 4 2010M. Wottawa Abstract Aim:, Hypoxia-inducible gene expression is an important physiological adaptive mechanism in response to a decreased oxygen supply. We have recently described an oxygen- and prolyl-4-hydroxylase (PHD)3-dependent stabilization of the activating transcription factor 4 (ATF-4). The aim of the present study was to examine if the normoxic destabilization of ATF-4 is regulated by oxygen-dependent proteasomal degradation. Methods:, We determined poly-ubiquitination of ATF-4 in normoxia compared to hypoxia by immunoprecipitation and immunoblots. Furthermore, we analysed the expression of the ATF-4 target gene GADD153 as a function of oxygen concentration. Results:, ATF-4 protein levels were not detectable in normoxia. Normoxic degradation correlated with an oxygen-dependent poly-ubiquitination of ATF-4, which was hindered by hypoxic incubation of the cells. As a result of hypoxia, GADD153 was expressed. The hypoxic GADD153 expression was attenuated or increased by transfecting the cells with ATF-4 siRNA or PHD3 siRNA respectively. Conclusion:, Our results demonstrate the involvement of oxygen-dependent proteasomal degradation of ATF-4 in the hypoxia-induced expression of GADD153. Taken together, hypoxia/PHD3-regulated stabilization of ATF-4 by hindering oxygen-dependent degradation may play a critical role in linking cell fate decisions to oxygen availability. [source] Functions of glutamate transporters in cerebellar Purkinje cell synapsesACTA PHYSIOLOGICA, Issue 1 2009Y. Takayasu Abstract Glutamate transporters play a critical role in the maintenance of low extracellular concentrations of glutamate, which prevents the overactivation of post-synaptic glutamate receptors. Four distinct glutamate transporters, GLAST/EAAT1, GLT-1/EAAT2, EAAC1/EAAT3 and EAAT4, are distributed in the molecular layer of the cerebellum, especially near glutamatergic synapses in Purkinje cells (PCs). This review summarizes the current knowledge about the differential roles of these transporters at excitatory synapses of PCs. Data come predominantly from electrophysiological experiments in mutant mice that are deficient in each of these transporter genes. GLAST expressed in Bergmann glia contributes to the clearing of the majority of glutamate that floods out of the synaptic cleft immediately after transmitter release from the climbing fibre (CF) and parallel fibre (PF) terminals. It is indispensable to maintain a one-to-one relationship in synaptic transmission at the CF synapses by preventing transcellular glutamate spillover. GLT-1 plays a similar but minor role in the uptake of glutamate as GLAST. Although the loss of neither GLAST nor GLT-1 affects cerebellar morphology, the deletion of both GLAST and GLT-1 genes causes the death of the mutant animal and hinders the folium formation of the cerebellum. EAAT4 removes the low concentrations of glutamate that escape from uptake by glial transporters, preventing the transmitter from spilling over into neighbouring synapses. It also regulates the activation of metabotropic glutamate receptor 1 (mGluR1) in perisynaptic regions at PF synapses, which in turn affects mGluR1-mediated events including slow EPSCs and long-term depression. No change in synaptic function is detected in mice that are deficient in EAAC1. [source] The role of caveolin-1 in cardiovascular regulationACTA PHYSIOLOGICA, Issue 2 2009A. Rahman Abstract Caveolae are omega-shaped membrane invaginations present in essentially all cell types in the cardiovascular system, and numerous functions have been ascribed to these structures. Caveolae formation depends on caveolins, cholesterol and polymerase I and transcript release factor-Cavin (PTRF-Cavin). The current review summarizes and critically discusses the cardiovascular phenotypes reported in caveolin-1-deficient mice. Major changes in the structure and function of heart, lung and blood vessels have been documented, suggesting that caveolae play a critical role at the interface between blood and surrounding tissue. According to an emerging paradigm, many of these changes are secondary to uncoupling of endothelial nitric oxide synthase. Thus, nitric oxide synthase not only synthesizes more nitric oxide in the absence of caveolin-1, but also more superoxide with potential pathogenic consequences. It is further argued that the vasodilating drive from increased nitric oxide production in caveolin-1-deficient mice is balanced by changes in the vascular media that favour increased dynamic resistance regulation. Harnessing the therapeutic opportunities buried in caveolae, while challenging, could expand the arsenal of treatment options in cancer, lung disease and atherosclerosis. [source] MAKING DELINQUENT FRIENDS: ADULT SUPERVISION AND CHILDREN'S AFFILIATIONS,CRIMINOLOGY, Issue 1 2005MARK WARR Although having delinquent friends is one of the strongest known correlates of delinquent behavior, criminologists have been curiously silent as to why some adolescents acquire delinquent friends and others do not. Analysis of data from the national Survey of Parents and Children reveals a strong association between forms of direct and indirect parental supervision and the kinds of friends that adolescents make. Parents who closely monitor their children's affiliations exhibit a variety of traits typical of involved or conscientious parents. Indirect supervision also appears to mediate the effect of attachment to parents, one of the few established correlates of delinquent friendships. These and other findings illustrate the critical role that parent-child relations play in the process of making delinquent friends. [source] Decoding epithelial signals: critical role for the epidermal growth factor receptor in controlling intestinal transport functionACTA PHYSIOLOGICA, Issue 1 2009D. F. McCole Abstract The intestinal epithelium engages in bidirectional transport of fluid and electrolytes to subserve the physiological processes of nutrient digestion and absorption, as well as the elimination of wastes, without excessive losses of bodily fluids that would lead to dehydration. The overall processes of intestinal ion transport, which in turn drive the secretion or absorption of water, are accordingly carefully regulated. We and others have identified the epidermal growth factor receptor (EGFr) as a critical regulator of mammalian intestinal ion transport. In this article, we focus on our studies that have uncovered the intricate signalling mechanisms downstream of EGFr that regulate both chloride secretion and sodium absorption by colonocytes. Emphasis will be placed on the EGFr-associated regulatory pathways that dictate the precise outcome to receptor activation in response to signals that may seem, on their face, to be quite similar if not identical. The concepts to be discussed underlie the ability of the intestinal epithelium to utilize a limited set of signalling effectors to produce a variety of outcomes suitable for varying physiological and pathophysiological demands. Our findings therefore are relevant not only to basic biological principles, but also may ultimately point to new therapeutic targets in intestinal diseases where ion transport is abnormal. [source] Expression of nebulette during early cardiac developmentCYTOSKELETON, Issue 4 2007Michael Esham Abstract Nebulette, a cardiac homologue of nebulin, colocalizes with ,-actinin in the pre-myofibrils of spreading cardiomyocytes and has been hypothesized to play a critical role in the formation of the thin-filament-Z-line complex early during myofibrillogenesis. Data from mesodermal explants or whole tissue mounts of developing hearts suggest that the pattern of myofibrillogenesis in situ may differ from observations of spreading cardiomyocytes. To evaluate the role of nebulette in myofibrillogenesis, we have analyzed the expression of nebulette in chicken heart rudiments by immunoblots and immunofluorescence. We detect the 110 kDa nebulette in heart rudiments derived from stage 9,10 using the anti-nebulin mAb, N114, or polyclonal anti-nebulette Abs by immunoblotting. Immunofluorescence analysis of explants stained with anti-nebulette and anti-,-actinin Abs demonstrates that both proteins localize along actin filaments in punctate to continuous manner at early stages of cardiac development and later give rise to striations. In both cases, the punctate staining had a periodicity of ,1.0 ,m indicating a pre-myofibrils distribution at the earliest time points examined. We demonstrate that nebulette is indeed associated with premyofibrils in very early stages of myofibrillogenesis and suggest that nebulette may play an important role in the formation of these structures. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source] Arabidopsis thaliana protein, ATK1, is a minus-end directed kinesin that exhibits non-processive movementCYTOSKELETON, Issue 3 2002Adam I. Marcus Abstract The microtubule cytoskeleton forms the scaffolding of the meiotic spindle. Kinesins, which bind to microtubules and generate force via ATP hydrolysis, are also thought to play a critical role in spindle assembly, maintenance, and function. The A. thaliana protein, ATK1 (formerly known as KATA), is a member of the kinesin family based on sequence similarity and is implicated in spindle assembly and/or maintenance. Thus, we want to determine if ATK1 behaves as a kinesin in vitro, and if so, determine the directionality of the motor activity and processivity character (the relationship between molecular "steps" and microtubule association). The results show that ATK1 supports microtubule movement in an ATP-dependent manner and has a minus-end directed polarity. Furthermore, ATK1 exhibits non-processive movement along the microtubule and likely requires at least four ATK1 motors bound to the microtubule to support movement. Based on these results and previous data, we conclude that ATK1 is a non-processive, minus-end directed kinesin that likely plays a role in generating forces in the spindle during meiosis. Cell Motil. Cytoskeleton 52:144,150, 2002. © 2002 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||