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Intracellular Enzymes (intracellular + enzyme)
Selected AbstractsPolymethylmethacrylate particles impair osteoprogenitor viability and expression of osteogenic transcription factors Runx2, osterix, and Dlx5JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2010Richard Chiu Abstract Polymethylmethacrylate (PMMA) particles have been shown to inhibit the differentiation of osteoprogenitor cells, but the mechanism of this inhibitory effect has not been investigated. We hypothesize that the inhibitory effects of PMMA particles involve impairment of osteoprogenitor viability and direct inhibition of transcription factors that regulate osteogenesis. We challenged MC3T3-E1 osteoprogenitors with PMMA particles and examined the effects of these materials on osteoprogenitor viability and expression of transcription factors Runx2, osterix, Dlx5, and Msx2. MC3T3-E1 cells treated with PMMA particles over a 72-h period showed a significant reduction in cell viability and proliferation as indicated by a dose- and time-dependent increase in supernatant levels of lactate dehydrogenase, an intracellular enzyme released from dead cells, a dose-dependent decrease in cell number and BrdU uptake, and the presence of large numbers of positively labeled Annexin V-stained cells. The absence of apoptotic cells on TUNEL assay indicated that cell death occurred by necrosis, not apoptosis. MC3T3-E1 cells challenged with PMMA particles during the first 6 days of differentiation in osteogenic medium showed a significant dose-dependent decrease in the RNA expression of Runx2, osterix, and Dlx5 on all days of measurement, while the RNA expression of Msx2, an antagonist of Dlx5-induced osteogenesis, remained relatively unaffected. These results indicate that PMMA particles impair osteoprogenitor viability and inhibit the expression of transcription factors that promote osteoprogenitor differentiation. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:571,577, 2010 [source] The structure of an archaeal ribose-5-phosphate isomerase from Methanocaldococcus jannaschii (MJ1603)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 12 2009Richard W. Strange Ribose-5-phosphate isomerase is a ubiquitous intracellular enzyme of bacterial, plant and animal origin that is involved in the pentose phosphate cycle, an essential component of cellular carbohydrate metabolism. Specifically, the enzyme catalyses the reversible conversion of ribose 5-phosphate to ribulose 5-phosphate. The structure of ribose-5-phosphate isomerase from Methanocaldococcus jannaschii has been solved in space group P21 to 1.78,Å resolution using molecular replacement with one homotetramer in the asymmetric unit and refined to an R factor of 14.8%. The active site in each subunit was occupied by two molecules of propylene glycol in different orientations, one of which corresponds to the location of the phosphate moiety and the other to the location of the furanose ring of the inhibitor. [source] Application of Cavitational reactors for cell disruption for recovery of intracellular enzymesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2008Parag R. Gogate Abstract Cavitational reactors are a novel and promising form of multiphase reactors, based on the principle of release of a large amount of energy owing to the violent collapse of cavities. This paper presents an overview of cavitational reactors in the specific area of cell disruption for the recovery of intracellular enzymes, in terms of the basic aspects, different reactor configurations including recommendations for optimum operating parameters and review of earlier literature reports. It has been observed that under optimized conditions, cavitational reactors can reduce the energy requirement for the release of intracellular enzymes by an order of magnitude compared with conventional cell disruption techniques used on an industrial scale. However, problems associated with efficient scale-up and operation at conditions required for industrial scale, hamper the successful utilization of cavitational reactors at this time. Some recommendations have been made for the future work required to realize the dream of harnessing the spectacular effects of cavitation phenomena. Copyright © 2008 Society of Chemical Industry [source] Effect of the nitrogen source on caffeine degradation by Aspergillus tamariiLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2004G. Gutiérrez-Sánchez Abstract Aims:, To evaluate caffeine degradation and nitrogen requirements during Aspergillus tamarii growth in submerged culture. Methods and Results:,Aspergillus tamarii spores produced on a coffee infusion agar medium added with sucrose were used. Several caffeine and ammonium sulphate concentrations (0,1 and 0,1·36 g l,1, respectively) were tested simultaneously on fungal biomass production and caffeine degradation. An additional caffeine pulse (4 g l,1) was added for all experiments after 48 h of fermentation. Results revealed that when using 0·90 g l,1 of caffeine and 0·14 g l,1 of ammonium sulphate, biomass production and caffeine degradation were enhanced. Highest biomass production (Xmax = 9·87 g l,1) with a specific growth rate (,) of 0·073 h,1 and caffeine degradation rate of 0·033 g l,1 h,1, was observed under these conditions. Conclusions:, Caffeine degradation as well as biomass production were characterized. Significance and Impact of the Study:, These studies set the stage for future characterization studies of intracellular enzymes involved in caffeine degradation. Moreover, results observed may help in the biotreatment of residues from the coffee agroindustry. [source] Arachidonic acid-mediated cooxidation of all- trans -retinoic acid in microsomal fractions from human liverBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2000Louise Nadin The quantitative importance of prostaglandin H synthase (PGHS)-mediated cooxidation of all- trans -retinoic acid (ATRA) was evaluated in human liver microsomes (n=17) in relation to CYP-dependent ATRA 4-hydroxylation. Observed rates of ATRA cooxidation (4.6,20 pmol mg protein,1 min,1) and 4-hydroxylation (8.7,45 pmol mg protein,1 min,1) were quantitatively similar and exhibited similar individual variation (4 and 5 fold, respectively). From kinetic studies cooxidation was an efficient process in human hepatic microsomes (VmaxKm,1=0.25) compared with NADPH- and NADH-mediated 4-hydroxylation by CYP (VmaxKm,1=0.14 and 0.02, respectively). The capacity of lipid hydroperoxide metabolites of arachidonic acid to mediate ATRA oxidation was established directly, but downstream products (D, E, F and I-series prostaglandins) were inactive. cDNA-expressed CYPs supported ATRA oxidation by lipid hydroperoxides. Whereas CYPs 2C8, 2C9 and 3A4, but not CYPs 1A2 or 2E1, were effective catalysts of the NADPH-mediated reaction, cooxidation supported by 15(S)-hydroperoxyeicosatetraenoic acid was mediated by all five CYPs. The cooxidation reaction in human hepatic microsomes was inhibited by the CYP inhibitor miconazole. These findings indicate that ATRA oxidation is quantitatively significant in human liver. Lipid hydroperoxides generated by intracellular enzymes such as prostaglandin synthase and lipoxygenases are sources of activated oxygen for CYP-mediated deactivation of ATRA to polar products. British Journal of Pharmacology (2000) 131, 851,857; doi:10.1038/sj.bjp.0703579 [source] | |||||||||||||