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Adequate Concentrations (adequate + concentration)
Selected AbstractsEffect of methylxanthines on production of cellulases by Penicillium echinulatumJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007M. Camassola Abstract Aim:, In this work, the effect of supplementing liquid cellulase production media (CPM) with methylxanthines (aminophylline, caffeine and theophylline), with and without the addition of glucose, on the secretion of cellulases by Penicillium echinulatum strain 2HH (wild-type) and the derived mutant strain 9A02S1 was studied. Methods and Results:, When compared with unsupplemented CPM, both strains produced higher , -glucosidase and filter paper activities (FPAs) in CPM supplemented with 1 ,mol l,1 of caffeine but lower activities with 5 ,mol l,1 of caffeine. With theophylline only, strain 9A02S1 produced higher , -glucosidase and FPAs, while aminophylline produced no effect on the cellulase activity of either strain. Supplementation of CPM with 0·5% (w/v) of glucose plus caffeine resulted in higher , -glucosidase and FPAs being produced by strain 2HH, but not strain 9A02S1, than in CPM supplemented with 0·5% (w/v) of glucose only. Conclusions:, These results indicate that different concentrations of caffeine and theophylline can increase the , -glucosidase and FPAs produced by P. echinulatum strains 2HH and 9A02S1. Significance and Impact of the Study:, The results suggest that some methylxanthines, in adequate concentration, can be used as media components to increase cellulase production. [source] Evaluation of practical diets containing different protein levels on gonad development of female redclaw crayfish Cherax quadricarinatusAQUACULTURE NUTRITION, Issue 4 2009H. RODRÍGUEZ-GONZÁLEZ Abstract The effect of five experimental diets with different crude protein content (220, 270, 330, 390 and 450 g kg,1) on gonad development of female Cherax quadricarinatus was tested under laboratory conditions. After 70 days, a significant linear relationship indicated that higher concentrations of protein and carbohydrates in the hepatopancreas were produced as the dietary crude protein increased (P < 0.05). There were significant responses of the gonadosomatic index, hepatosomatic index, biochemical composition of the gonad (protein, lipids, carbohydrates and energy) and frequency of secondary vitellogenic oocytes to dietary protein level, as indicated by significant fits of the quadratic equation to the observed experimental data. The optimal response of the criteria parameters corresponded to levels of crude protein in the range 284,355 g kg,1. Overall, 330 g kg,1 crude protein with a protein : energy ratio of 15.6 mg kJ,1 was considered the most adequate concentration of dietary protein for gonad development and biochemical composition in female redclaw crayfish. [source] Mannich and O -Alkylation Reactions of Tetraalkoxyresorcin[4]arenes , The Use of Some Products in Ligand-Assisted ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2006Benjamin R. Buckley Abstract The measurement of the pKa of racemic tetramethoxyresorcin[4]arenes explains the failure to obtain good yields in attempted Mannich reactions of these substrates under classical reaction conditions. The failure is related to the lack of adequate concentrations of the iminium ions that results from the reduced acid strength of tetraalkoxyresorcin[4]arenes compared with that of the parent octahydroxyresorcin[4]arenes. However, the preparation of a series of Mannich bases derived from racemic tetraalkoxyresorcin[4]arenes was accomplished under microwave-assisted aprotic reaction conditions and the use of preformed iminium ion intermediates. When the reactions were carried out with the use of chiral bis(aminol) ethers, mixtures of diastereomers were obtained that could be separated by flash chromatography. The absolute configurations of the enantiomerically pure tetrabenzoxazine derivatives were established in some cases by X-ray crystallographic analysis and by a comparison of the nuclear magnetic resonance spectroscopic data. The alkylation of racemic tetramethoxyresorcin[4]arenes was achieved with the use of an excess of 2-bromo- N -[(R)-(+)-(,-methylbenzyl)]acetamide in acetonitrile containing potassium carbonate. Enantioselective ligand-assisted reactions of aromatic aldehydes are also reported with the use of dialkylzinc reagents both in the absence and in the presence of terminal alkynes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Localized delivery of growth factors for periodontal tissue regeneration: Role, strategies, and perspectives,MEDICINAL RESEARCH REVIEWS, Issue 3 2009Fa-Ming Chen Abstract Difficulties associated with achieving predictable periodontal regeneration, means that novel techniques need to be developed in order to regenerate the extensive soft and hard tissue destruction that results from periodontitis. Localized delivery of growth factors to the periodontium is an emerging and versatile therapeutic approach, with the potential to become a powerful tool in future regenerative periodontal therapy. Optimized delivery regimes and well-defined release kinetics appear to be logical prerequisites for safe and efficacious clinical application of growth factors and to avoid unwanted side effects and toxicity. While adequate concentrations of growth factor(s) need to be appropriately localized, delivery vehicles are also expected to possess properties such as protein protection, precision in controlled release, biocompatibility and biodegradability, self-regulated therapeutic activity, potential for multiple delivery, and good cell/tissue penetration. Here, current knowledge, recent advances, and future possibilities of growth factor delivery strategies are outlined for periodontal regeneration. First, the role of those growth factors that have been implicated in the periodontal healing/regeneration process, general requirements for their delivery, and the different material types available are described. A detailed discussion follows of current strategies for the selection of devices for localized growth factor delivery, with particular emphasis placed upon their advantages and disadvantages and future prospects for ongoing studies in reconstructing the tooth supporting apparatus. © 2009 Wiley Periodicals, Inc. Med Res Rev, 29, No. 3, 472-513, 2009 [source] Curcumin in Cancer Chemoprevention: Molecular Targets, Pharmacokinetics, Bioavailability, and Clinical TrialsARCHIV DER PHARMAZIE, Issue 9 2010Adeeb Shehzad Abstract Curcumin (diferuloylmethane), a derivative of turmeric is one of the most commonly used and highly researched phytochemicals. Abundant sources provide interesting insights into the multiple mechanisms by which curcumin may mediate chemotherapy and chemopreventive effects on cancer. The pleiotropic role of this dietary compound includes the inhibition of several cell signaling pathways at multiple levels, such as transcription factors (NF-,B and AP-1), enzymes (COX-2, MMPs), cell cycle arrest (cyclin D1), proliferation (EGFR and Akt), survival pathways (,-catenin and adhesion molecules), and TNF. Curcumin up-regulates caspase family proteins and down-regulates anti-apoptotic genes (Bcl-2 and Bcl-XL). In addition, cDNA microarrays analysis adds a new dimension for molecular responses of cancer cells to curcumin at the genomic level. Although, curcumin's poor absorption and low systemic bioavailability limits the access of adequate concentrations for pharmacological effects in certain tissues, active levels in the gastrointestinal tract have been found in animal and human pharmacokinetic studies. Currently, sufficient data has been shown to advocate phase II and phase III clinical trials of curcumin for a variety of cancer conditions including multiple myeloma, pancreatic, and colon cancer. [source] Structural flexibility, an essential component of the allosteric activation in Escherichia coli glucosamine-6-phosphate deaminaseACTA CRYSTALLOGRAPHICA SECTION D, Issue 1 2002E. Rudiño-Piñera A new crystallographic structure of the free active-site R conformer of the allosteric enzyme glucosamine-6-phosphate deaminase from Escherichia coli, coupled with previously reported structures of the T and R conformers, generates a detailed description of the heterotropic allosteric transition in which structural flexibility plays a central role. The T conformer's external zone [Horjales et al. (1999), Structure, 7, 527,536] presents higher B values than in the R conformers. The ligand-free enzyme (T conformer) undergoes an allosteric transition to the free active-site R conformer upon binding of the allosteric activator. This structure shows three alternate conformations of the mobile section of the active-site lid (residues 163,182), in comparison to the high B values for the unique conformation of the T conformer. One of these alternate R conformations corresponds to the active-site lid found when the substrate is bound. The disorder associated with the three alternate conformations can be related to the biological regulation of the Km of the enzyme for the reaction, which is metabolically required to maintain adequate concentrations of the activator, which holds the enzyme in its R state. Seven alternate conformations for the active-site lid and three for the C-terminus were refined for the T structure using isotropic B factors. Some of these conformers approach that of the R conformer in geometry. Furthermore, the direction of the atomic vibrations obtained with anisotropic B refinement supports the hypothesis of an oscillating rather than a tense T state. The concerted character of the allosteric transition is also analysed in view of the apparent dynamics of the conformers. [source] | ||||||||||