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Chemical Inhibition (chemical + inhibition)
Selected AbstractsMethyl palmitate inhibits lipopolysaccharide-stimulated phagocytic activity of rat peritoneal macrophagesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 6 2006Swapna Sarkar Abstract Macrophages, in general, are critical effectors of body's immune system. Chemical inhibition of phagocytic activity of such macrophages as Kupffer cells has been extensively studied. We have earlier shown that methyl palmitate (MP) inhibits the activation of Kupffer cells. To evaluate the potential of MP to inhibit the activation of other macrophages, we treated rat peritoneal macrophages with varying concentrations of MP. Its treatment led to a dose-dependent inhibition of phagocytic activity, which was found to be 34%, 47%, and 66% at 0.25, 0.50, and 1.0 mM MP, respectively, as measured by latex bead uptake. When MP-treated peritoneal macrophages were stimulated with lipopolysaccharide (LPS), the nitric oxide (.NO) release was inhibited at 6 h, while cyclooxygenase-2 expression decreased after 24 h. The treatment with MP increased the release of interleukin (IL)-10 in the LPS-treated cells at 6 h, while IL-6 and tumor necrosis factor-, were significantly increased both at 6 and 24 h. Our data suggest that MP inhibits phagocytic activity and . NO production similar to that observed in isolated Kupffer cells. Therefore, inhibition of phagocytosis by MP may be a general phenomenon, and it could be used as an inhibitor of macrophage function. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:302,308, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20150 [source] STY1 regulates auxin homeostasis and affects apical,basal patterning of the Arabidopsis gynoeciumTHE PLANT JOURNAL, Issue 1 2006Joel J. Sohlberg Summary Gynoecia of the Arabidopsis mutant sty1-1 display abnormal style morphology and altered vascular patterning. These phenotypes, which are enhanced in the sty1-1 sty2-1 double mutant, suggest that auxin homeostasis or signalling might be affected by mutations in STY1 and STY2, both members of the SHI gene family. Chemical inhibition of polar auxin transport (PAT) severely affects the apical,basal patterning of the gynoecium, as do mutations in the auxin transport/signalling genes PIN1, PID and ETT. Here we show that the apical,basal patterning of sty1-1 and sty1-1 sty2-1 gynoecia is hypersensitive to reductions in PAT, and that sty1-1 enhances the PAT inhibition-like phenotypes of pin1-5, pid-8 and ett-1 gynoecia. Furthermore, we show that STY1 activates transcription of the flavin monooxygenase-encoding gene THREAD/YUCCA4, involved in auxin biosynthesis, and that changes in expression of STY1 and related genes lead to altered auxin homeostasis. Our results suggest that STY1 and related genes promote normal development of the style and affect apical,basal patterning of the gynoecium through regulation of auxin homeostasis. [source] Quantitative measurement of serotonin synthesis and sequestration in individual live neuronal cellsJOURNAL OF NEUROCHEMISTRY, Issue 5 2005J. Balaji Abstract Synthesis and subsequent sequestration into vesicles are essential steps that precede neurotransmitter exocytosis, but neither the total neurotransmitter content nor the fraction sequestered into vesicles have been measured in individual live neurons. We use multiphoton microscopy to directly observe intracellular and intravesicular serotonin in the serotonergic neuronal cell line RN46A. We focus on how the relationship between synthesis and sequestration changes as synthesis is up-regulated by differentiation or down-regulated by chemical inhibition. Temperature-induced differentiation causes an increase of about 60% in the total serotonin content of individual cells, which goes up to about 10 fmol. However, the number of vesicles per cell increases by a factor of four and the proportion of serotonin sequestered inside the vesicles increases by a factor of five. When serotonin synthesis is inhibited in differentiated cells and the serotonin content goes down to the level present in undifferentiated cells, the sequestered proportion still remains at this high level. The total neurotransmitter content of a cell is, thus, an unreliable indicator of the sequestered amount. [source] Creating a mutant luciferase resistant to HPV chemical inhibition by random mutagenesis and colony-level screeningLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2006Eileen Kim-Choi Abstract Firefly luciferase covers a wide range of applications. One common usage of the bioluminescence assay is the measurement of intracellular concentration of adenosine triphosphate (ATP) for cell viability. However, inhibition of the enzyme reaction by chemicals in the assay has so far limited the application of luciferase for high production volume (HPV) chemical testing. The objective of this research was to obtain a mutant luciferase with increased stability to inhibition by HPV chemicals, yet retaining specific activity comparable to, or better than, wild-type luciferase. The enzymatic properties of the wild-type luciferase were improved by random mutagenesis and colony-level screening. In this paper, the detailed process of creating mutant luciferases for testing the toxicity of HPV chemicals is described. As a result, two mutant luciferases were created, with different degrees of improved tolerance to inhibition by chloroform and other HPV chemicals. Copyright © 2006 John Wiley & Sons, Ltd. [source] German cockroach proteases regulate matrix metalloproteinase-9 in human bronchial epithelial cellsALLERGY, Issue 8 2006K. Page Background:, Matrix metalloproteinases (MMPs) digest extracellular matrix proteins and may play a role in the pathogenesis of bronchial asthma. MMP-9 levels are increased in the bronchoalveolar lavage fluid and sputum of asthmatics compared with that of controls. As exposure to cockroaches is an environmental risk factor for asthma, we sought to investigate the role of German cockroach fecal remnants (frass) on MMP-9 expression. Methods:, Human bronchial epithelial cells (16HBE14o-) and primary normal human bronchial epithelial cells were treated with cockroach frass in the absence or presence of tumor necrosis factor (TNF),. MMP-9 mRNA, protein levels and pro-MMP-9 activity were determined using real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and zymogram assays. Pretreatment of frass with aprotinin abolished protease activity. PD98059, a chemical inhibitor of extracellular signal regulated kinase (ERK), and SLIGKV, an activator of protease-activated receptor (PAR)-2 were also used. AP-1DNA binding was determined by electrophoretic mobility shift assay (EMSA) and ERK phosphorylation by Western blot analysis. Results:, Cockroach frass augmented TNF, -mediated MMP-9 mRNA and protein expression by a mechanism dependent on active serine proteases within frass and not on endogenous endotoxin. Frass increased ERK phosphorylation, and chemical inhibition of ERK attenuated cockroaches' effects on MMP-9. Serine proteases are known to activate the PAR-2 receptor. We found that selective activation of PAR-2 using the peptide SLIGKV augmented TNF, -induced MMP-9 protein levels and increased ERK phosphorylation. Frass and SLIGKV each increased AP-1 translocation and DNA binding. Conclusions:, These data suggest that German cockroach frass contains active serine proteases which augment TNF, -induced MMP-9 expression by a mechanism involving PAR-2, ERK and AP-1. [source] Anatomy, physiology, and pathophysiology of the pedunculopontine nucleus,,MOVEMENT DISORDERS, Issue 3 2009Ned Jenkinson PhD Abstract The pedunculopontine nucleus is composed of cholinergic and non-cholinergic neurones and is located in the caudal pontomesencephalic tegmentum. Evidence suggests that the nucleus plays a role in the production and control of movement. The nucleus has dense interconnections with the basal ganglia, as well as with other areas of the brain associated with motor control. Electrical stimulation of the pedunculopontine nucleus in the decerebrate cat or rat produces organized locomotor movements. Physiological studies show that the pedunculopontine nucleus modulates its activity in response to locomotion, as well as voluntary arm and eye movements. Degeneration of the pedunculopontine nucleus is seen in post-mortem brains in humans with Parkinson's disease and Parkinsonian syndromes. In animal models of Parkinson's disease, metabolic changes are seen in the pedunculopontine nucleus, and chemical inhibition or mechanical disruption of the nucleus can produce an akinetic state in animals and man. In this paper we review the literature in support of the suggestion that some of the symptoms of Parkinson's disease are caused by dysfunction of the pedunculopontine nucleus. In accordance with this view, direct stimulation of the nucleus can ameliorate some symptoms of the disease, as demonstrated in both experimental animals and man. © 2008 Movement Disorder Society [source] Nerve growth factor mediates steroid-resistant inflammation in respiratory syncytial virus infection,,PEDIATRIC PULMONOLOGY, Issue 6 2007Lida Mohtasham MD Abstract Neurotrophic factors and receptors are upregulated in the respiratory tract of humans and rodents infected by the respiratory syncytial virus, leading to airway inflammation and hyperreactivity. The contribution of neurotrophic pathways to the recruitment of immuno-inflammatory cells and their response to anti-inflammatory therapy remains unclear. We sought to determine whether selective nerve growth factor inhibition prevents the immuno-inflammatory response against infection, and explored the effect of inhaled corticosteroids on virus-induced neurotrophic upregulation and the consequent recruitment of immuno-inflammatory cells into the airways. We tried to inhibit the recruitment of lymphocytes and monocytes into the airways of infected weanling rats using immunologic inhibition of nerve growth factor with a specific blocking antibody, or chemical inhibition of receptor tyrosine kinase with K252a. The anti-inflammatory activity of inhaled corticosteroids was studied in infected rats treated with budesonide, fluticasone, or vehicle. Immunological or chemical inhibition of nerve growth factor or its high-affinity receptor tyrosine kinase pathway inhibited the recruitment of inflammatory cells triggered by nociceptive irritation of infected rat airways, thereby reducing local and systemic immuno-inflammatory responses against the virus. Neurotrophic upregulation in infected airways was not affected by inhaled corticosteroids. As a logical consequence, these commonly used drugs were also unable to stop the recruitment of immune and inflammatory effector cells into infected airways. Overexpression of neurotrophic factors and receptors in airways infected by respiratory syncytial virus is critical for the development of airway inflammation and hyperreactivity, which is resistant to the anti-inflammatory effect of inhaled corticosteroids. Pediatr Pulmonol. 2007; 42:496,504. © 2007 Wiley-Liss, Inc. [source] Genetic or chemical protease inhibition causes significant changes in the Bacillus subtilis exoproteomePROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2008Lidia Westers Abstract Bacillus subtilis is a prolific producer of enzymes and biopharmaceuticals. However, the susceptibility of heterologous proteins to degradation by (extracellular) proteases is a major limitation for use of B. subtilis as a protein cell factory. An increase in protein production levels has previously been achieved by using either protease-deficient strains or addition of protease inhibitors to B. subtilis cultures. Notably, the effects of genetic and chemical inhibition of proteases have thus far not been compared in a systematic way. In the present studies, we therefore compared the exoproteomes of cells in which extracellular proteases were genetically or chemically inactivated. The results show substantial differences in the relative abundance of various extracellular proteins. Furthermore, a comparison of the effects of genetic and/or chemical protease inhibition on the stress response triggered by (over) production of secreted proteins showed that chemical protease inhibition provoked a genuine secretion stress response. From a physiological point of view, this suggests that the deletion of protease genes is a better way to prevent product degradation than the use of protease inhibitors. Importantly however, studies with human interleukin-3 show that chemical protease inhibition can result in improved production of protease-sensitive secreted proteins even in mutant strains lacking eight extracellular proteases. [source] | ||||||||||||||||