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Terms modified by Kp Selected AbstractsEvaluating best evaporation estimate model for water surface evaporation in semi-arid region, IndiaHYDROLOGICAL PROCESSES, Issue 8 2008Shakir Ali Abstract Evaluating performances of four commonly used evaporation estimate methods, namely; Bowen ratio energy balance (BREB), mass transfer (MT), Priestley,Taylor (PT) and pan evaporation (PE), based on 4 years experimental data, the most effective and the reliable evaporation estimates model for the semi-arid region of India has been derived. The various goodness-of-fit measures, such as; coefficient of determination (R2), index of agreement (D), root mean square error (RMSE), and relative bias (RB) have been chosen for the performance evaluation. Of these models, the PT model has been found most promising when the Bowen ratio, , is known a priori, and based on its limited data requirement. The responses of the BREB, the PT, and the PE models were found comparable to each other, while the response of the MT model differed to match with the responses of the other three models. The coefficients, , of the BREB, µ of the MT, , of the PT and KP of the PE model were estimated as 0·07, 2·35, 1·31 and 0·65, respectively. The PT model can successfully be extended for free water surface evaporation estimates in semi-arid India. A linear regression model depicting relationship between daily air and water temperature has been developed using the observed water temperatures and the corresponding air temperatures. The model helped to generate unrecorded water temperatures for the corresponding ambient air temperatures. Copyright © 2007 John Wiley & Sons, Ltd. [source] The effect of solvents on the rate of catalytic hydrogenation of 6-ethyl-1,2,3,4-tetrahydroanthracene-9,10-dioneINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2008ch Fajt The rate of hydrogenation of 6-ethyl-1,2,3,4-tetrahydroanthracene-9,10-dione was investigated at 313 K and 0.1 MPa in 20 solvents. A multiple linear regression was used to describe the solvent effect. The regression of the reaction rates was carried out using two five-parameter linear regression models: the Abraham,Kamlet,Taft (AKT) and the Koppel,Palm (KP) model. After the elimination of the insignificant terms from the regression models, it was found that the basic character of the solvent and its Hildebrand cohesion energy density were the most important attributes influencing the hydrogenation rate. The analysis of both models led to the same conclusion. The resultant simplified AKT model gave closer fitting in comparison to the KP model. The results could facilitate the solvent selection for the industrial process of hydrogen peroxide production by the anthraquinone method with respect to the kinetics of anthraquinone hydrogenation. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 240,252, 2008 [source] Psychosine-induced apoptosis and cytokine activation in immune peripheral cells of Krabbe patients,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2007Patrizia Formichi Globoid cell leukodystrophy or Krabbe disease (KD), is a hereditary disorder caused by galactosylceramidase deficiency. Progressive accumulation of psychosine is considered to be the critical pathogenetic mechanism of cell death in the Krabbe brain. Psychosine mechanism of action has not been fully elucidated. It seems to induce apoptosis in oligodendrocytes through a mitochondrial pathway and to up-regulate inflammatory cytokines production resulting in oligodendrocyte loss. Our aim was to evaluate the role of psychosine in apoptotic cell death and inflammatory response in a group of patients affected by KD using peripheral blood lymphocytes (PBLs) and peripheral blood mononuclear cells (PBMCs) as a cellular model. PBLs from KP and healthy controls were exposed to 20 µM psychosine and analysed by flow cytometry, agarose gel electrophoresis and fluorescence microscopy. Our results showed that psychosine induces apoptosis in PBLs through a mitochondrial pathway, but the apoptotic response was quite low especially KP. The role of psychosine in the up-regulation of cytokines (TNFalpha, IL8 and MCP1) has been evaluated by ELISA in PBMCs from KP and controls after stimulation with LPS and phytohemagglutinin. Both in basal condition and after LPS stimulation, cells from KP showed a significant increase in TNF-, production, reduced MCP1 levels and no modification in IL8. These results indicate that lymphomonocytes from KP had a basal proinflammatory pattern that was amplified by psychosine. In conclusion, the reduced apoptotic response and the atypical cytokine production observed in our experiments, suggest an involvement of inflammatory pattern in immune peripheral cells of KP. J. Cell. Physiol. 212:737,743, 2007. © 2007 Wiley-Liss, Inc. [source] Palm oil mill effluent pretreatment using Moringa oleifera seeds as an environmentally friendly coagulant: laboratory and pilot plant studiesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2006Subhash Bhatia Abstract This research paper covers the suitability of the coagulation,flocculation process using Moringa oleifera seeds after oil extraction as a natural and environmentally friendly coagulant for palm oil mill effluent treatment. The performance of M. oleifera coagulant was studied along with the flocculant KP 9650 in removal of suspended solids, organic components and in increasing the floc size. The optimum values of the operating parameters obtained from the laboratory jar test were applied in a pilot-scale treatment plant comprised of coagulation,flocculation and filtration processes. Pilot-scale pretreatment resulted in 99.7% suspended solids removal, 71.5% COD reduction, 68.2% BOD reduction, 100% oil and grease removal and 91% TKN removal. In pilot plant pretreatment, the percentage recovery of water was 83.3%, and 99.7% sludge was recovered after dewatering in a filter press. Copyright © 2006 Society of Chemical Industry [source] Effects of Practical Constraints on Item Selection Rules at the Early Stages of Computerized Adaptive TestingJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2004Shu-Ying Chen The purpose of this study was to compare the effects of four item selection rules,(1) Fisher information (F), (2) Fisher information with a posterior distribution (FP), (3) Kullback-Leibler information with a posterior distribution (KP), and (4) completely randomized item selection (RN),with respect to the precision of trait estimation and the extent of item usage at the early stages of computerized adaptive testing. The comparison of the four item selection rules was carried out under three conditions: (1) using only the item information function as the item selection criterion; (2) using both the item information function and content balancing; and (3) using the item information function, content balancing, and item exposure control. When test length was less than 10 items, FP and KP tended to outperform F at extreme trait levels in Condition 1. However, in more realistic settings, it could not be concluded that FP and KP outperformed F, especially when item exposure control was imposed. When test length was greater than 10 items, the three nonrandom item selection procedures performed similarly no matter what the condition was, while F had slightly higher item usage. [source] Effect of ketoprofen in topical formulation on vascular endothelial growth factor expression and tumor growth in nude mice with osteosarcomaJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2004Kenshi Sakayama Abstract OST cells, a low metastatic cell line established from human osteosarcoma, were inoculated under the periosteum of the ossa cranii of nude mice. Four weeks later, tumors were percutaneously treated for an additional 4 weeks with a patch containing either placebo or ketoprofen (KP). In the placebo group, OST cells formed osteoid and invaded the cranial bone. Tumor mass weighed 3.54 g. Approximately 85% of cells within the tumor expressed proliferating cell nuclear antigen (PCNA), indicating that they were proliferating with a high mitotic activity. Many feeder vessels were located within the tumor. The majority of tumor cells expressed intensely vascular endothelial growth factor (VEGF). In the KP group, invasion of OST cells into the cranial bone was suppressed and the tumor mass was 47% of that of the placebo group. Approximately 65% of cells within the tumor were PCNA-negative, indicating that their growth was arrested. There were considerably fewer feeder vessels within the tumor in the KP group than in the placebo group. Only a small number of cells expressed VEGF. Based on these findings, we concluded that topical administration of KP to nude mice with osteosarcoma inhibited VEGF expression, reduced the development of feeder vessels for supply of nutrients and oxygen, and suppressed tumor growth. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Interactions of cyclosporines with lipid membranes as studied by solid-state nuclear magnetic resonance spectroscopy and high-sensitivity titration calorimetryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2002Uwe Schote Abstract Cyclosporin A (CyA) interacts with lipid membranes. Binding reaction and membrane location of CyA and analogs were examined with 2H-NMR, high-sensitivity isothermal titration calorimetry (ITC), and CD spectroscopy. Effects of CyA and charged analogs on the phosphocholine head group and on the membrane interior were investigated using selectively deuterated phospholipids. Incorporation of cyclosporin generated small disordering of the lipid acyl chains. Binding of CyA and neutral and positively charged analogs to lipid membranes showed endothermic heats of reaction between +,5.9 and +,11.3 kcal/mol, whereas enthalpy of binding was close to zero for the negatively charged derivative. Binding constants of cyclosporines to liposomal membranes were in the range of KP,=,1650,5560 M,,1 depending on the cholesterol content. 2H-NMR provides evidence that CyA is essentially located in the interior of the bilayer membrane. For the charged analogs an additional interaction occurs at the head group level, placing the polar groups of these CyA analogs in the vicinity of the phosphocholine dipoles. The association of CyA and its analogs is accompanied by a positive enthalpy change, which is overcompensated by positive entropy changes. Binding of CyA to lipid membranes thus follows the classical hydrophobic effect, which is in contrast to many other peptide-lipid binding reactions. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91: 856,867, 2002 [source] Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 79JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003U Del Carro Peripheral neuropathy is one of the most common secondary complications of diabetes mellitus, causing severe and prolonged morbidity. However, clinical and experimental studies have reported that careful glucose control may prevent, stabilize, and/or reverse neuropathy and other chronic diabetic complications. Unfortunately, insulin therapy does not prevent the development or progression of chronic lesions in the vessels, kidneys, eyes, or nerves of the diabetic patient. There is great interest in investigating other forms of endocrine replacement therapy, such as transplantation of the pancreas or of the islets of Langerhans (IT). Diabetic polyneuropathy (DP) evolution is characterized by progressive demyelination and axonal loss and is manifested by signs and symptoms on physical examination and abnormalities in nerve conduction studies (NCS). NCS provide reliable, noninvasive, objective measures of peripheral nerve function and constitute the most important technique for the evaluation of the severity of DP in clinical trials. Several research groups have demonstrated that skin biopsy with measurement of intraepidermal nerve fiber density is another method minimally invasive and repeatable that provides direct pathologic evidence of axonal damage in diabetic neuropathy. Fifty-one consecutive IDDM patients with or without end stage renal disease were enrolled at the moment of islet (Is), kidney (KD), kidney-pancreas (KP) or kidney-islet (KI) transplantation. Patients underwent skin biopsy punch, neurologic examination and neurophysiological investigation. Particularly, 20 pts underwent KP tx, 16 KD tx, 10 islet tx and 5 KI. The patients were comparable for duration of diabetes, dialysis (when present), age, lipid profile. In half of the patients a follow-up of 2 years has been reached. After KP tx, and partially with KI, a complete normalization of glycometabolic control has been achieved, with statistically lower HbA1c in comparison with KD group (KP = 6.2; 0.1% vs. KD = 8.4; 0.5%; p < 0.01). In the KI/Is group, a long-term restoration of islet endocrine function has been achieved, with insulin independence. When this has been lost, a persistent secretion of C-peptide was shown for a long period of time. This was correlated with a global improvement quality of life and vascular structure. Preliminary results will be presented. [source] Interest-Based Negotiations in a Transformed Labor,Management SettingNEGOTIATION JOURNAL, Issue 1 2004Nils O. Fonstad The authors introduce a group of essays that evolved from a March 2003 symposium on the path-breaking new partnership and use of interest-based negotiation (IBN) at Kaiser Permanente (KP), one of the largest integrated health care programs in the United States. They briefly trace the history of the IBN approach (both success stories and failures); the growth of this phenomenon; and its use in collective bargaining settings. The KP case, the focus of the symposium (which was jointly sponsored by MIT's Institute for Work and Employment Relations and Harvard's Program on Negotiation), is by far the largest instance of the use of IBN in U.S. labor relations history. [source] NMR solution structure of KP-TerB, a tellurite-resistance protein from Klebsiella pneumoniaePROTEIN SCIENCE, Issue 4 2008Sheng-Kuo Chiang Abstract Klebsiella pneumoniae (KP), a Gram-negative bacterium, is a common cause of hospital-acquired bacterial infections worldwide. Tellurium (Te) compounds, although relatively rare in the environment, have a long history as antimicrobial and therapeutic agents. In bacteria, tellurite (TeO3,2) resistance is conferred by the ter (Ter) operon (terZABCDEF). Here, on the basis of 2593 restraints derived from NMR analysis, we report the NMR structure of TerB protein (151 amino acids) of KP (KP-TerB), which is mainly composed of seven ,-helices and a 310 helix, with helices II to V apparently forming a four-helix bundle. The ensemble of 20 NMR structures was well-defined, with a RMSD of 0.32 ± 0.06 Å for backbone atoms and 1.11 ± 0.07 Å for heavy atoms, respectively. A unique property of the KP-TerB structure is that the positively and negatively charged clusters are formed by the N-terminal positively and C-terminal negatively charged residues, respectively. To the best of our knowledge, the protein sequence and structures of KP-TerB are unique. [source] The Role of Opiorphins (Endogenous Neutral Endopeptidase Inhibitors) in Urogenital Smooth Muscle BiologyTHE JOURNAL OF SEXUAL MEDICINE, Issue S3 2009Kelvin Paul Davies BSc ABSTRACT Introduction., The opiorphins are a newly characterized class of peptides that act as potent endogenous neutral endopeptidase (NEP) inhibitors. Recent reports have suggested that they play an important role in erectile physiology. Aim., This article reviews recent developments that increase our understanding of the role of the opiorphin family of peptides in erectile physiology. Methods., During a microarray screen of gene changes that occur in a rat diabetic model of erectile dysfunction (ED), Vcsa1 was one of the most down-regulated genes in the rat corpora. Quantitative real-time polymerase chain reaction demonstrated that in at least three models of diseases that result in ED (diabetes, aging, and cavernous nerve [CN] transection), Vcsa1 was down-regulated in the rat corpora. The human opiorphin family of genes (hSMR3A/B and ProL1) also acts as markers of erectile function in patients with ED. Main Outcome Measures., The reader will be informed of the most current research regarding the role of opiorphins in urogenital smooth muscle biology. Results., These observations led to the suggestion that genes encoding opiorphins (and potentially their peptide products) can act as markers of ED. Gene transfer of plasmids overexpressing Vcsa1 in aging rats, as well as intracorporal injection of sialorphin, led to an improvement in erectile function. In organ bath studies, we demonstrated that sialorphin can cause increased rates of relaxation of corporal smooth muscle (CSM). We have also demonstrated that in vitro, Vcsa1 causes changes in the expression of G-protein-coupled receptors (GPCRs). This has led us to suggest that the action of Vcsa1 on erectile physiology may act through relaxation of CSM by its ability to act as an inhibitor of NEP, therefore prolonging the action of peptide agonists at their GPCRs. Conclusions., Overall, there is a growing body of evidence that the opiorphins play a role in regulating CSM tone and thereby erectile function. Davies KP. The role of opiorphins (endogenous neutral endopeptidase inhibitors) in urogenital smooth muscle biology. J Sex Med 2009;6(suppl 3):286,291. [source] 1361: Main anterior entities 2: granulomatousACTA OPHTHALMOLOGICA, Issue 2010F WILLERMAIN Purpose During uveitis, inflammatory cells and epitheloid cells can aggregates on the corneal endothelium forming keratic precipitates (KPs). Methods On slit lamp examination, KP's can have different forms and locations. Once they are large with a mutton fat appearance, uveitis will be classified as granulomatous. Results Granulomatous uveitis is a heterogeneous group of disease with anterior, intermediate and panuveitis. Granulomatous uveitis can be due to several infectious and non infectious causes, but masquerade syndromes and idiopathic cases must also been ruled out. Conclusion This course will first describe the main clinical characteristics of those different entities. A standard work-up procedure will then be proposed. [source] Sharp bounds for the number of 3-independent partitions and the chromaticity of bipartite graphsJOURNAL OF GRAPH THEORY, Issue 1 2001F. M. Dong Abstract Given a graph G and an integer k,,,1, let ,(G,,k) denote the number of k -independent partitions of G. Let ,,,s(p,q) (resp., ,,2,s(p,q)) denote the family of connected (resp., 2-connected) graphs which are obtained from the complete bipartite graph Kp,q by deleting a set of s edges, where p,,,q,,,2. This paper first gives a sharp upper bound for ,(G,3), where G ,,,,,,s(p,q) and 0,,,s,,,(p,,,1)(q,,,1) (resp., G ,,,,,2,s(p,q) and 0,,,s,,,p,+,q,,,4). These bounds are then used to show that if G ,,,,,,s(p,q) (resp., G ,,,,,2,s (p,q)), then the chromatic equivalence class of G is a subset of the union of the sets ,,,si(p+i,q,i) where max and si,=,s,,,i(p,q+i) (resp., a subset of ,,2,s(p,q), where either 0,,,s,,,q,,,1, or s,,,2q,,,3 and p,,,q,+,4). By applying these results, we show finally that any 2-connected graph obtained from Kp,q by deleting a set of edges that forms a matching of size at most q,,,1 or that induces a star is chromatically unique. © 2001 John Wiley & Sons, Inc. J Graph Theory 37: 48,77, 2001 [source] An investigation into the influence of counterion on the RS -propranolol and S -propranolol skin permeabilityJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2010Francesco Cilurzo Abstract The effects of two contra-ions, namely benzoate (Bz) and oleate (Ol), on the in vitro human skin permeability of propranolol racemate (RS -PR) or S -enantiomer (S -PR) were studied. Saline solution (SS) or mineral oil (MO) were selected as vehicles. The MO increased the permeability coefficient (Kp) of PR-Bz (pKp,,,4) of about four times with respect to SS (pKp,,,8) probably due to the ion pair formation. The steady-state flux of S -enantiomers resulted about twofold higher than that of racemates according to their lower melting temperatures with the exception of (S)-PR-Ol and (RS)-PR-Ol vehicled in SS which not resulted statistically different. This anomalous result could be explained considering the behavior of (RS)-PR-Ol or (S)-PR-Ol in aqueous solutions: these salts formed ion pairs which associated to form aggregates up to a concentration of 20,µg/mL as verified by light scattering. Therefore, their effective concentrations in SS resulted similar and justified the overlapped skin permeation profiles. All three considered variables, namely counterion, vehicle, and chirality, resulted mutually interfering on and deeply influenced the passive diffusion process of PR. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1217,1224, 2010 [source] Human skin permeation and partition: General linear free-energy relationship analysesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2004Michael H. Abraham Abstract Literature values of the permeability coefficient for permeation of human skin from water have been adjusted for ionization in water and adjusted for temperature. The obtained values of log Kp for 119 solutes at 37°C have been correlated with Abraham descriptors to yield an equation with R2,=,0.832 and SD,=,0.46 log units. Three separate test sets of 60 compounds had log Kp predicted with an SD of 0.48 log units. The main factors that influence log Kp are solute hydrogen bond basicity that lowers the permeability coefficient and solute volume that increases the permeability coefficient. Human skin,water partition coefficients, as log Ksc, have been collected for 45 compounds and yield an equation with R2,=,0.926 and SD,=,0.22 log units. We have compared the log Kp equation to equations for various other processes, but have found no process that appears to be similar to that for skin permeation. The nearest process to skin,water partition is the isobutanol,water partition system. An equation for lateral diffusion in the stratum corneum is shown to be reasonably close to various diffusion-related processes. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1508,1523, 2004 [source] Kinetics of styrene emulsion polymerization above the critical micelle concentration: Effect of the initial monomer concentration on the molecular weightJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2005Jorge Herrera-Ordonez Abstract The emulsion polymerization of styrene above the critical micelle concentration has been experimentally studied from a low final polymer content up to a high polymer content (,50%). A maximum in the molecular weight (M) evolution has been observed in all cases. The presence or absence of such a maximum depends on the relative values of the rate of free-radical entry (,) and the rate of chain transfer to the monomer (KtrCMp, where Ktr is the chain transfer to monomer rate coefficient and CMp is the monomer concentration in particles). If , , KtrCMp, M is constant and equal to Kp/Ktr (where Kp is the propagation rate coefficient), except at very low particles sizes typical of the early stages of the reaction, in which the chain length is limited by the particle size. On the other hand, if , , KtrCMp, M is determined by both CMp and ,. It is proposed that , is determined by the sum of the entry of the oligomeric radicals formed in the aqueous phase and those contained in particles that undergo limited coagulation. This coagulative entry can become very significant; therefore, reactor hydrodynamics can play a major role in the kinetic behavior observed. Disagreement between Clay and Gilbert's model and molecular weight distribution data can be ascribed, to a lesser or greater extent, to the degree of correctness of the quasi-steady-state and instantaneous-termination approaches. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1963,1972, 2005 [source] Rapid Prototyping of Piezoelectric Ceramics via Selective Laser Sintering and GelcastingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Dong Guo This article presents a new lost mold rapid prototyping method which combines selective laser sintering (SLS) and gelcasting techniques for fabricating piezoelectric ceramics. SLS was used to fabricate sacrificial molds of the desired structure of the ceramic part. Then aqueous PZT (lead zirconate titanate) suspension was cast in the mold and solidified in situ through formation of a three-dimensional network gel. Because the polymer mold can be easily removed at the initial stage of sintering and the gelcast PZT body has a high green strength, the desired geometry of the PZT part can be completely retained after sintering of the ceramics. Complex-shaped PZT parts were successfully fabricated after using concentrated PZT suspension with low viscosity. Densities and electrical properties, such as the d33, the relative permittivity ,, the dielectric loss tg, and the electromechanical coupling factor Kp of the gelcast PZT parts were also compared with those of the die-pressed PZT samples. The results indicated that the gel-forming process did not deteriorate the electrical properties of the samples, if proper dispersant was selected in developing concentrated ceramic slurry. [source] Recent data on the number of active centers and propagation rate constants in olefin polymerization with supported ZN catalystsMACROMOLECULAR SYMPOSIA, Issue 1 2004V.A. Zakharov Abstract Data on the number of active centers (Cp) and propagation rate constants (Kp) have been obtained by means of polymerization quenching with 14CO of propylene and ethylene polymerization with supported titanium-magnesium catalysts (TMC) with different composition. In the case of propylene polymerization the Cp and Kp values have been measured separately for isospecific, aspecific and low stereospecific centers. Effects of MgCl2 support, internal and external donors are discussed on the basis of data obtained. Data on the strong effect of diffusion limitation at ethylene polymerization with number of TMC have been obtained and a set of methods have been used to exclude this effect. Data on Cp and Kp values at ethylene polymerization with low stereospecific and highly stereospecific catalysts are presented. [source] Matrix Representation of Polymer Chain Size Distributions, 2,MACROMOLECULAR THEORY AND SIMULATIONS, Issue 2 2007Fundamental Analysis of Linear Polymerization Mechanisms at Transient Conditions Abstract Analysis of the mass balance equations that describe a reaction system may be useful to provide information about its dynamics, such as the restricted set of compositions that can be achieved from a given set of initial compositions and the effect of feeding reactants to the reaction environment along the reaction course. Since these results may be important for the formulation of reaction policies, this work presents the properties of a matrix polymerization model previously developed and extended to describe transient conditions. This model is based on the definitions of two matrices: the consumption matrix (A,,,Kt), which contains information about chemical transformations among the many active polymer species in the system, and the propagation matrix Kp, which contains information about chain growth. It is shown that the set of mass balance equations that describes the dynamics of active chemical species in polymerization reactions has a stable and unique solution, which is bounded if feed rates are also bounded. It is also shown that the set of compositions that may be reached through manipulation of the feed rates is restricted and may not include all possible chemical compositions. Finally, it is shown that the obtained molecular weight distributions are special multiple time convolutions of the initiation rates. [source] The effect of temperature on C4 -type leaf photosynthesis parametersPLANT CELL & ENVIRONMENT, Issue 9 2007RAIA-SILVIA MASSAD ABSTRACT C4 -type photosynthesis is known to vary with growth and measurement temperatures. In an attempt to quantify its variability with measurement temperature, the photosynthetic parameters , the maximum catalytic rate of the enzyme ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) (Vcmax), the maximum catalytic rate of the enzyme phosphoenolpyruvate carboxylase (PEPC) (Vpmax) and the maximum electron transport rate (Jmax) , were examined. Maize plants were grown in climatic-controlled phytotrons, and the curves of net photosynthesis (An) versus intercellular air space CO2 concentrations (Ci), and An versus photosynthetic photon flux density (PPFD) were determined over a temperature range of 15,40 °C. Values of Vcmax, Vpmax and Jmax were computed by inversion of the von Caemmerer & Furbank photosynthesis model. Values of Vpmax and Jmax obtained at 25 °C conform to values found in the literature. Parameters for an Arrhenius equation that best fits the calculated values of Vcmax, Vpmax and Jmax are then proposed. These parameters should be further tested with C4 plants for validation. Other model key parameters such as the mesophyll cell conductance to CO2 (gi), the bundle sheath cells conductance to CO2 (gbs) and Michaelis,Menten constants for CO2 and O2 (Kc, Kp and Ko) also vary with temperature and should be better parameterized. [source] Active-Site Concentrations of Chemicals , Are They a Better Predictor of Effect than Plasma/Organ/Tissue Concentrations?BASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2010Margareta Hammarlund-Udenaes In contrast, the total concentrations of the drug in plasma/organ/tissue also include the protein- or tissue-bound molecules that are pharmacologically inactive. Plasma and whole tissue concentrations are used as predictors of effects and side effects because of their ease of sampling, while the concentrations of unbound drug in tissue are more difficult to measure. However, with the introduction of microdialysis and subsequently developed techniques, it has become possible to test the free drug hypothesis. The brain is an interesting organ in this regard because of the presence of the blood-brain barrier with its tight junctions and active efflux and influx transporters. We have proposed that research into brain drug delivery be divided into three main areas: the rate of delivery (PS, CLin), the extent of delivery (Kp,uu) and the non-specific affinity of the drug to brain tissue, described by the volume of distribution of unbound drug in the brain (Vu,brain). In this way, the concentration of unbound drug at the target site can be estimated from the total brain concentration and the plasma concentration after measuring the fraction of unbound drug. Results so far fully support the theory that active site concentrations are the best predictors when active transport is present. However, there is an urgent need to collect more relevant data for predicting active site concentrations in tissues with active transporters in their plasma membranes. [source] Geomagnetic field effect on cardiovascular regulationBIOELECTROMAGNETICS, Issue 2 2004Juraj Gmitrov Abstract The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, Kp, Ak, and Ap indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min hemodynamic monitoring sequences were carried out in rabbits sedated by pentobarbital infusion (5 mg/kg/h). We examined the arterial baroreflex effects on the short term blood pressure and heart rate (HR) variabilities reflected by the standard deviation (SD) of the average values of the mean femoral arterial blood pressure (MAP) and the HR. Baroreflex sensitivity (BRS) was estimated from blood pressure/HR response to intravenous (i.v.) bolus injections of vasoconstrictor (phenylephrine) and vasodilator (nitroprusside) drugs. We found a significant negative correlation of increasing GMF disturbance (Kp) with BRS (P,=,0.008), HR SD (P,=0.022), and MAP SD (P,=,0.002) signifying the involvement of the arterial baroreflex mechanism. The abrupt change in geomagnetic disturbance from low (K,=,0) to high (K,=,4,5) values was associated with a significant increase in MAP (83,±,5 vs. 99,±,5 mm Hg, P,=,0.045) and myocardial oxygen consumption, measured by MAP and HR product (24100,±,1800 vs. 31000,±,2500 mm Hg,·,bpm, P,=,0.034), comprising an additional cardiovascular risk. Most likely, GMF affects brainstem and higher neural cardiovascular regulatory centers modulating blood pressure and HR variabilities associated with the arterial baroreflex. Bioelectromagnetics 25:92,101, 2004. © 2004 Wiley-Liss, Inc. [source] Permeability and toxicological profile estimation of organochlorine compounds by biopartitioning micellar chromatographyBIOMEDICAL CHROMATOGRAPHY, Issue 4 2009L. Escuder-Gilabert Abstract This paper points out the usefulness of biopartitioning micellar chromatography (BMC) as a high-throughput primary screening tool providing key information about the oral absorption, skin permeability (Kp), brain,blood distribution coefficient (BB) and ecotoxicological parameters such as median lethal concentration (LC50) and bioconcentration factors of 15 organochloride compounds. The retention data of compounds in BMC conditions were interpolated in previously developed quantitative,retention activity relationships by our research group. Results show that the compounds studied readily cross the intestinal barrier (oral absorption >ercnt;) and the blood,brain barrier (log BB >p;0.4). In addition, the organochlorines DDE, chlorobenzene, 1,3-dichlorobenzene and 1,2-dichlorobenzene are the compounds which can more quickly cross the skin barrier (log Kp >nus;0.74 cm/h). From a ecotoxicological point of view, it can be concluded that the most retained compounds, DDE, DDD, hexachlorobenzene and dicofol, are the most toxic and bioacumulative. Copyright © 2008 John Wiley & Sons, Ltd. [source] Affinity-enhanced protein partitioning in decyl ,- D -glucopyranoside two-phase aqueous micellar systemsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Henry Lam Abstract Liquid,liquid extraction in two-phase aqueous complex-fluid systems has been proposed as a scalable, versatile, and cost-effective purification method for the downstream processing of biotechnological products. In the case of two-phase aqueous micellar systems, careful choices of the phase-forming surfactants or surfactant mixtures allow these systems to separate biomolecules based on size, hydrophobicity, charge, or specific affinity. In this article, we investigate the affinity-enhanced partitioning of a model affinity-tagged protein,green fluorescent protein fused to a family 9 carbohydrate-binding module (CBM9-GFP),in a two-phase aqueous micellar system generated from the nonionic surfactant n -decyl ,- D -glucopyranoside (C10G1), which acts simultaneously as the phase-former and the affinity ligand. In this simple system, CBM9-GFP was extracted preferentially into the micelle-rich phase, despite the opposing tendency of the steric, excluded-volume interactions operating between the protein and the micelles. We obtained more than a sixfold increase (from 0.47 to 3.1) in the protein partition coefficient (Kp), as compared to a control case where the affinity interactions were "turned off" by the addition of a competitive inhibitor (glucose). It was demonstrated conclusively that the observed increase in Kp can be attributed to the specific affinity between the CBM9 domain and the affinity surfactant C10G1, suggesting that the method can be generally applied to any CBM9-tagged protein. To rationalize the observed phenomenon of affinity-enhanced partitioning in two-phase aqueous micellar systems, we formulated a theoretical framework to model the protein partition coefficient. The modeling approach accounts for both the excluded-volume interactions and the affinity interactions between the protein and the surfactants, and considers the contributions from the monomeric and the micellar surfactants separately. The model was shown to be consistent with the experimental data, as well as with our current understanding of the CBM9 domain. © 2005 Wiley Periodicals, Inc. [source] Nitrogen and Phosphorus Release from Decomposing Leaves under Sub-Humid Tropical Conditions,BIOTROPICA, Issue 2 2001A. B. Kwabiah ABSTRACT For many soils of the tropics, inputs of organic materials are essential to sustain soil fertility and crop production. Research in the quality of organic inputs, a key factor controlling rates of decomposition and nutrient release, continues to guide selection and use of organic materials as nutrient sources. The relationship between decomposition patterns and the quality parameters of the fresh leaves of six agroforestry species: Sesbania sesban, Croton megalocarpus, Calliandra calothyrsus, Tithonia diversifolia, Lantana camara, and Senna spectabilis, was investigated in a litterbag study over a period of 77 days in the highlands of western Kenya. The litterbags were buried 1 cm below the soil surface and covered with soil of ca 1 cm thickness. Percent leaf mass and total N and P that remained with time strongly correlated with total P and C/P ratio (R2= 0.60-0.90) during the first 35 days of study; but afterwards, correlation was stronger with the initial soluble polyphenolics (Pp)/P ratio (R2= 0.69-0.92) than with total P and C/P ratio. Loss of leaf mass and release of N and P followed the exponential function, yt= y0* e- kt, from which the specific decay rate constants (k) were calculated for loss of leaf mass (kB) and release of N (kN) and P (Kp). Among the plant species, the k values were lowest in Calliandra with kB= 0.012/d, kN= 0.017/d and kp= 0.044/d. Lantana had the highest K values with kg= 0.067/d and kp= 0.119/d, but the highest kN value of 0.109/d occurred in Tithonia. The kB values for all organic materials were lower than their corresponding kN and kp values, suggesting that leaching of N and P from litters may have augmented the microbial mineralization of N and P. There was a strong correlation between the kB, kN, and kp values and total P (r = 0.82-0.96; P 0.01), but not total N, lignin (LIG), or Pp. Rates of N and P release followed the general trend: Tithonia > Senna > Lantana > Sesbania > Croton > Calliandra. The results indicated that, among the quality parameters studied, total P is the most important factor controlling rate of decomposition and N and P release from organic inputs in the area of study. [source] Addressing Central Nervous System (CNS) Penetration in Drug Discovery: Basics and Implications of the Evolving New ConceptCHEMISTRY & BIODIVERSITY, Issue 11 2009Andreas Reichel Abstract Despite enormous efforts, achieving a safe and efficacious concentration profile in the brain remains one of the big challenges in central nervous system (CNS) drug discovery and development. Although there are multiple reasons, many failures are due to underestimating the complexity of the brain, also in terms of pharmacokinetics (PK). To this day, PK support of CNS drug discovery heavily relies on improving the blood,brain barrier (BBB) permeability in vitro and/or the brain/plasma ratio (Kp) in vivo, even though neither parameter can be reliably linked to pharmacodynamic (PD) and efficacy readouts. While increasing BBB permeability may shorten the onset of drug action, an increase in the total amount in brain may not necessarily increase the relevant drug concentration at the pharmacological target. Since the traditional Kp ratio is based on a crude homogenization of brain tissue, it ignores the compartmentalization of the brain and an increase favors non-specific binding to brain lipids rather than free drug levels. To better link exposure/PK to efficacy/PD and to delineate key parameters, an integrated approach to CNS drug discovery is emerging which distinguishes total from unbound brain concentrations. As the complex nature of the brain requires different compartments to be considered when trying to understand and improve new compounds, several complementary parameters need to be measured in vitro and in vivo, and integrated into a coherent model of brain penetration and distribution. The new paradigm thus concentrates on finding drug candidates with the right balance between free fraction in plasma and brain, and between rate and extent of CNS penetration. Integrating this data into a coherent model of CNS distribution which can be linked to efficacy will allow it to design compounds with an optimal mix in physicochemical, pharmacologic, and pharmacokinetic properties, ultimately mitigating the risk for failures in the clinic. [source] Quality by design, part I: Application of NIR spectroscopy to monitor tablet manufacturing processJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2008Simin Hassannejad Tabasi Abstract To monitor tableting production using near infrared (NIR) spectroscopy, chemometric models were developed to analyze peak compression force, crushing strength and content uniformity. To measure tablet content uniformity, orbifloxacin tablets with drug content ranging from 60 to 90 mg were made and analyzed using ultraviolet (UV) and NIR spectroscopy. To assess the compression force and crushing strength, several batches of tablets were made on a Stokes B2 rotary tablet press and compression force was varied from 360 to 3500 lb. Principal component analysis (PCA) was used to identify tablets with regular and capped tablets breakage patterns. Comparison of statistical parameters showed that partial least squares (PLS) models gave better fit than the multiple linear regression (MLR) models. The best fit PLS models had a standard error of calibration (SEC) and a standard error of prediction (SEP) for content uniformity of 1.13 and 1.36 mg; for compression force of 69.86 and 59.48 lb and for crushing strength 0.55 kP and 0.57 kP, respectively. NIR spectroscopy in combination with multivariate modeling is a rapid and nondestructive technique that could reliably predict content uniformity, compression force and crushing strength for orbifloxacin tablets. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:4040,4051, 2008 [source] Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) CatalystsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2006Artem A. Barabanov Abstract Summary: The number of active centers (CP) and propagation rate constants (kP) for polymerization of ethylene with supported catalysts LFeCl2/SiO2, LFeCl2/Al2O3 and LFeCl2/MgCl2 (L,=,2,6-(2,6-(Me)2C6H3NCMe)2C5H3N), activated by an Al(i -Bu)3 co-catalyst, were determined by a method of polymerization inhibition with radioactive 14CO. In contrast to homogeneous systems based on LFeCl2, the supported catalysts are highly active and stable in ethylene polymerization at 70,80,°C. In the presence of hydrogen, the activity of the supported catalysts substantially increases (2,4 fold). The data obtained on the effect of hydrogen on the calculated CP and kP values suggests that for ethylene polymerization without hydrogen, the "dormant" active centers are formed in the catalytic systems. A scheme for the formation of these "dormant" centers and their reactivation in presence of hydrogen is suggested. For the investigated supported catalysts the CP values were found to be only 2 to 4% of the total iron complex content in the catalysts. The kP value for the catalysts prepared using different supports (SiO2, Al2O3 and MgCl2) were close (3.2,×,104 to 4.5,×,104 L,·,(mol,·,s),1 at 70,°C). The support composition affects neither the molecular mass (MM) nor the molecular mass distribution (MMD) of the polymers produced. The obtained CP and kP values and data on the polymer MM and MMD lead to conclusion that the nature of the support has almost no effect on the structure of the active centers and the distribution of their reactivity. Effect of support on the MMD of PE produced over supported LFeCl2 catalysts. [source] Ferroelectric, piezoelectric, pyroelectric and Raman spectroscopy studies on BaTi0.9(Fe1/2Nb1/2)0.1O3 ceramicPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2008Z. Abdelkafi Abstract The hysteresis, piezoelectric and pyroelectric properties were measured in the temperature range near the ferroelectric,paraelectric phase transition. The BaTi0.9(Fe1/2Nb1/2)0.1O3 ceramic exhibits typical ferroelectric P ,E hysteresis behavior with a remanant polarization, Pr, of about 7.52 ,C/cm2 detected at 155 K. The electromechanical properties of this composition were measured using the resonance method. The ceramic provides high piezoelectric performance at the temperature of transition (Tmax = 216 K): the piezoelectric constant is d31 = 140 pC/N and the electromechanical coupling factor was kP = 22%. The pyroelectric study confirms the dielectric and ferroelectric measurements. The pyroelectric coefficient is about 125 nC/cm2 K at Tmax. Raman spectra of BaTi0.9(Fe1/2Nb1/2)0.1O3 ceramic were taken at various temperatures and measured over the wave number range from 150 to 1300 cm,1. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of solute lipophilicity on penetration through canine skinAUSTRALIAN VETERINARY JOURNAL, Issue 12 2003PC MILLS Objective To investigate the effect of lipophilicity on the percutaneous penetration of a homologous series of alcohols through canine skin Design Skin harvested from Greyhound thorax was placed in Franz-type diffusion cells and the in vitro passage of radio-labelled (14C) alcohols (ethanol, butanol, hexanol and octanol (Log P 0.19 - 3.0)) through separate skin sections was measured in replicates of five. Permeability coefficient (kP, cm/h), maximum flux (Jmax, mol/cm2/h) and residue remaining within the skin were determined. Results The kP increased with increasing lipophilicity (6.2 times 10 -4± 1.6 times 10 -4 cm/h for ethanol to 1.8 times 10 -2± 3.6 times 10 -3 cm/h for octanol). Alcohol residues remaining within each skin sample followed a similar pattern. An exponential decrease in Jmax with increasing lipophilicity was observed. Conclusion Changes in canine skin permeability occur with increasing alcohol lipophilicity. This finding has practical consequences for the design of topical formulations and optimisation of drug delivery through animal skin. [source] | |||||||||||||||||||||||||