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Interaction Study (interaction + study)
Selected AbstractsA Ferromagnetically Coupled, Bent, Trinuclear Copper(II) Complex: Synthesis, Structure, Hydrogen-Bonding Network, Magnetic Properties and DNA Interaction StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2006Sumana Sarkar Abstract A bent trinuclear copper(II) complex (1) incorporating ,-phenoxo, ,- syn - syn carboxylato, and ,3 -chloro bridges and an O,N,N -coordinated reduced Schiff-base ligand is reported. The complex shows an intramolecular ferromagnetic interaction in the solid state. The EPR spectra also support the magnetic behaviour of the complex. In the compound, each copper centre has a square-pyramidal geometry. The separation between the adjacent copper ions is about 3.05 Å and that between the terminal copper ions is about 5.0 Å. The complex forms a supramolecular architecture through N,H···Cl hydrogen bonding between the amine group of the reduced Schiff-base ligand and the counter chloride anions. Absorption and fluorescence spectral studies and viscosity measurements have been performed to determine the type of interaction with calf-thymus DNA. The nuclease activity of the complex with plasmid DNA is also studied. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Interaction study of a lysozyme-binding aptamer with mono- and divalent cations by ACEELECTROPHORESIS, Issue 3 2010Marie Girardot Abstract Binding between an aptamer and its target is highly dependent on the conformation of the aptamer molecule, this latter seeming to be affected by a variety of cations. As only a few studies have reported on the interactions of monovalent or divalent cations with aptamers, we describe herein the use of ACE in its mobility shift format for investigating interactions between various monovalent (Na+, K+, Cs+) or divalent (Mg2+, Ca2+, Ba2+) cations and a 30-mer lysozyme-binding aptamer. This study was performed in BGEs of different natures (phosphate and MOPS buffers) and ionic strengths. First, the effective charges of the aptamer in 30,mM ionic strength phosphate and MOPS (pH 7.0) were estimated to be 7.4 and 3.6, respectively. Then, corrections for ionic strength and counterion condensation effects were performed for all studies. The effective mobility shift was attributed not only to these effects, but also to a possible interaction with the buffer components (binary or ternary complexes) as well as possible conformational changes of the aptamer. Finally, apparent binding constants were calculated for divalent cations with mathematical linearization methods, and the influence of the nature of the BGE was evidenced. [source] Rufinamide: Clinical pharmacokinetics and concentration,response relationships in patients with epilepsyEPILEPSIA, Issue 7 2008Emilio Perucca Summary Rufinamide is a new, orally active antiepileptic drug (AED), which has been found to be effective in the treatment of partial seizures and drop attacks associated with the Lennox-Gastaut syndrome. When taken with food, rufinamide is relatively well absorbed in the lower dose range, with approximately dose-proportional plasma concentrations up to 1,600 mg/day, but less than dose-proportional plasma concentrations at higher doses due to reduced oral bioavailability. Rufinamide is not extensively bound to plasma proteins. During repeated dosing, steady state is reached within 2 days, consistent with its elimination half-life of 6,10 h. The apparent volume of distribution (Vd/F) and apparent oral clearance (CL/F) are related to body size, the best predictor being body surface area. Rufinamide is not a substrate of cytochrome P450 (CYP450) enzymes and is extensively metabolized via hydrolysis by carboxylesterases to a pharmacologically inactive carboxylic acid derivative, which is excreted in the urine. Rufinamide pharmacokinetics are not affected by impaired renal function. Potential differences in rufinamide pharmacokinetics between children and adults have not been investigated systematically in formal studies. Although population pharmacokinetic modeling suggests that in the absence of interacting comedication rufinamide CL/F may be higher in children than in adults, a meaningful comparison of data across age groups is complicated by age-related differences in doses and in proportion of patients receiving drugs known to increase or to decrease rufinamide CL/F. A study investigating the effect of rufinamide on the pharmacokinetics of the CYP3A4 substrate triazolam and an oral contraceptive interaction study showed that rufinamide has some enzyme-inducing potential in man. Findings from population pharmacokinetic modeling indicate that rufinamide does not modify the CL/F of topiramate or valproic acid, but may slightly increase the CL/F of carbamazepine and lamotrigine and slightly decrease the CL/F of phenobarbital and phenytoin (all predicted changes were <20%). These changes in the pharmacokinetics of associated AEDs are unlikely to make it necessary to change the dosages of these AEDs given concomitantly with rufinamide, with the exception that consideration should be given to reducing the dose of phenytoin. Based on population pharmacokinetic modeling, lamotrigine, topiramate, or benzodiazepines do not affect the pharmacokinetics of rufinamide, but valproic acid may increase plasma rufinamide concentrations, especially in children in whom plasma rufinamide concentrations could be increased substantially. Conversely, comedication with carbamazepine, vigabatrin, phenytoin, phenobarbital, and primidone was associated with a slight-to-moderate decrease in plasma rufinamide concentrations, ranging from a minimum of ,13.7% in female children comedicated with vigabatrin to a maximum of ,46.3% in female adults comedicated with phenytoin, phenobarbital, or primidone. In population modeling using data from placebo-controlled trials, a positive correlation has been identified between reduction in seizure frequency and steady-state plasma rufinamide concentrations. The probability of adverse effects also appears to be concentration-related. [source] Biphasic Resorbable Calcium Phosphate Ceramic for Bone Implants and Local Alendronate Delivery,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Shashwat S. Banerjee A novel biphasic calcium phosphate ceramic composed of tricalcium phosphate (TCP) and calcium pyrophosphate (CP) is synthesized in order to tailor the biodegradation behavior of the ceramic. The results show that biphasic TCP/CP ceramic has a strength of 62.2,±,2.1 MPa, which is superior to single-phase TCP and CP ceramics, which show strengths of 44.3,±,3.0 and 53.0,±,4.8 MPa, respectively. In addition, biphasic TCP/CP ceramic displays a controlled strength degradation from 62.2,±,2.1 to 40.5,±,1.0 MPa in stimulated body fluid over a period of 28 d. An in vitro cell materials interaction study using human fetal osteoblast cells indicates that TCP/CP ceramic is cytocompatible. TCP/CP ceramic also show a good loading capacity for alendronate. Adsorption of alendronate (AD) on the TCP/CP surface is found to proceed via ligand exchange mechanism and the in vitro release profile of AD from TCP/CP surface is characterized by an initial fast release followed by a slow and sustained release. Strong electrostatic interactions between AD groups and surface Ca2+ ions enable the slow and sustained release of AD. These results demonstrate that the newly developed biphasic ceramic, with its controlled strength degradation and drug release, shows promise for use in orthopedic and tissue engineering applications. [source] Case-only genome-wide interaction study of disease risk, prognosis and treatmentGENETIC EPIDEMIOLOGY, Issue 1 2010Brandon L. Pierce Abstract Case-control genome-wide association (GWA) studies have facilitated the identification of susceptibility loci for many complex diseases; however, these studies are often not adequately powered to detect gene-environment (G×E) and gene-gene (G×G) interactions. Case-only studies are more efficient than case-control studies for detecting interactions and require no data on control subjects. In this article, we discuss the concept and utility of the case-only genome-wide interaction (COGWI) study, in which common genetic variants, measured genome-wide, are screened for association with environmental exposures or genetic variants of interest. An observed G-E (or G-G) association, as measured by the case-only odds ratio (OR), suggests interaction, but only if the interacting factors are unassociated in the population from which the cases were drawn. The case-only OR is equivalent to the interaction risk ratio. In addition to risk-related interactions, we discuss how the COGWI design can be used to efficiently detect G×G, G×E and pharmacogenetic interactions related to disease outcomes in the context of observational clinical studies or randomized clinical trials. Such studies can be conducted using only data on individuals experiencing an outcome of interest or individuals not experiencing the outcome of interest. Sharing data among GWA and COGWI studies of disease risk and outcome can further enhance efficiency. Sample size requirements for COGWI studies, as compared to case-control GWA studies, are provided. In the current era of genome-wide analyses, the COGWI design is an efficient and straightforward method for detecting G×G, G×E and pharmacogenetic interactions related to disease risk, prognosis and treatment response. Genet. Epidemiol. 34:7,15, 2010. © 2009 Wiley-Liss, Inc. [source] Mirtazapine and paroxetine: a drug-drug interaction study in healthy subjectsHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 6 2001F. J. L. Ruwe Abstract Paroxetine inhibits cytochrome P450 2D6, which is involved in the metabolism of mirtazapine. The possible drug-drug interaction between two pharmacologically distinct antidepressants, mirtazapine and paroxetine, has been investigated in a randomized, three-way crossover study in 24 healthy male and female subjects. After a titration phase of 3 days, each subject received single daily doses of 30,mg mirtazapine, 40,mg paroxetine or the combination for 6 days. Assessments included serial blood sampling for pharmacokinetics at steady state, cognitive testing using the test battery of CDR Ltd, a visual analogue mood rating scale (Bond and Lader) and the Leeds Sleep Evaluation Questionnaire. Paroxetine inhibits the metabolism of mirtazapine, as shown by increases of approximately 17% and 25% of the 24,h AUC's of mirtazapine and its demethyl metabolite, respectively. Mirtazapine did not alter the pharmacokinetics of paroxetine. The combined administration of mirtazapine and paroxetine probably does not alter cognitive functioning or result in major changes on the visual analogue mood rating scale and Sleep Evaluation Questionnaire, compared with the administration of either drug alone. The incidence of adverse events was lower during combined administration of mirtazapine and paroxetine than during administration of either drug alone. Fatigue, dizziness, headache, nausea, anxiety and somnolence were the most common adverse events during combined administration. These data suggest that the combination of mirtazapine and paroxetine is unlikely to lead to clinically relevant drug-drug interactions and can be used without dose adjustment of either drug. The combination may even be better tolerated than either drug alone. Copyright © 2001 John Wiley & Sons, Ltd. [source] Ground states of BeC and MgC: A comparative multireference Brillouin,Wigner coupled cluster and configuration interaction study,INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005Vasilios I. Teberekidis Abstract The competing X3,, and 5,, states of the experimentally unknown alkaline,earth metal carbides BeC and MgC are examined with the multireference Brillouin,Wigner coupled cluster method restricted to single and double excitations (MRBW-CCSD). The results are compared against the traditional single-reference CCSD approach, as well as with other single and multireference methods. In both molecules, the CCSD 5,, , X3,, energy difference is underestimated, leading to an "erroneous" ground-state prediction in BeC. The MRBW-CCSD method corrects this anomalous behavior, leading to fair agreement with multireference configuration interaction (MR-CI) predictions. Our results at the highest levels of theory are extrapolated to the basis set limit, and the core/valence correlation is taken into account, leading to very accurate energetics and spectroscopic constants in both carbides. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Stacking interaction study of trans -resveratrol (trans -3,5,4,-trihydroxystilbene) in solution by Nuclear Magnetic Resonance and Fourier Transform Infrared SpectroscopyMAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2008Claudia Bonechi Abstract Interactions between aromatic rings or other unsaturated systems, including ,-stacking and face-to-edge complexes, are the origin of many phenomena in both organic and biological chemistry. It is well known that these interactions play an important role in the stabilization of the stereo-structure of DNA and the tertiary structure of many proteins. Trans -resveratrol (trans -3,5,4,-trihydroxystilbene, trans -RSV) is a phytoalexin found in Vitis sp. and in many other plants and food products and has received much attention because of its possible positive health benefits. In this work, the ,-stacking interaction of trans -RSV was studied by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. In particular, the proton chemical shift dependence of the RSV concentration in the range 2 × 10,2 , 1 × 10,5M and temperature were analysed. Moreover, the dynamics of the supramolecular aggregates were studied by nuclear spin relaxation data. Copyright © 2008 John Wiley & Sons, Ltd. [source] Interactions of Valeriana officinalis L. and Passiflora incarnata L. in a patient treated with lorazepamPHYTOTHERAPY RESEARCH, Issue 12 2009María Consuelo Carrasco Abstract There is an increasing interest in the health risks related to the use of herbal remedies. Although most consumers think that phytomedicines are safe and without side effects, interactions between complementary alternative and conventional medicines are being described. The aim of this clinical case report is to highlight the importance of the safe use of herbal remedies by providing a clinical interaction study between pharmaceutical medicines and herbal medicinal products. The case of a patient self-medicated with Valeriana officinalis L. and Passiflora incarnata L. while he was on lorazepam treatment is described. Handshaking, dizziness, throbbing and muscular fatigue were reported within the 32 h before clinical diagnosis. The analysis of family medical history ruled out essential tremor, Parkinson's disease, Wilson's disease and other symptom-related pathologies. His medical history revealed a generalized anxiety disorder and medicinal plant consumption but no neurological disorder. Appropriate physical examination was carried out. An additive or synergistic effect is suspected to have produced these symptoms. The active principles of Valerian and passionflower might increase the inhibitory activity of benzodiazepines binding to the GABA receptors, causing severe secondary effects. Due to the increase in herbal product self-medication, the use of herbal remedies should be registered while taking the personal clinical history. Multidisciplinary teams should be created to raise studies on medicinal plants with impact on medical praxis. Copyright © 2009 John Wiley & Sons, Ltd. [source] Expression, refolding, crystallization and preliminary crystallographic study of MHC H-2Kk complexed with octapeptides and nonapeptidesACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2004Christine Kellenberger Major histocompatibility complex (MHC) molecules are heterodimeric cell-surface receptors that play a crucial role in the cellular immune response by presenting epitope peptides to T-cell antigen receptors (TCR). Although the structural basis of the peptide,MHC binding mechanism is becoming better understood, it is still difficult to predict a binding mode for an MHC of unknown structure. Therefore, as the first stage of a TCR,MHC interaction study, the crystal structures of the mouse H-2Kk molecule in complex with both an octapeptide from Influenza A virus and a nonapeptide from simian virus SV40 were solved. Here, the expression, refolding, purification and crystallization of the two complexes are reported. For the H-2Kk,HA(259,266) complex, crystals were obtained via an extensive screen using a nanodrop-dispensing robot and diffracted to 2.5,Å resolution. For the H-2Kk,SV40(560,568) complex, microscopic needles were initially obtained and their size was improved by macroseeding and a stepwise increase in precipitant concentration. Diffraction data to a resolution of 3.0,Å were collected at a synchrotron facility. [source] A Systematic Approach for Scale-Down Model Development and Characterization of Commercial Cell Culture ProcessesBIOTECHNOLOGY PROGRESS, Issue 3 2006Feng Li The objective of process characterization is to demonstrate robustness of manufacturing processes by understanding the relationship between key operating parameters and final performance. Technical information from the characterization study is important for subsequent process validation, and this has become a regulatory expectation in recent years. Since performing the study at the manufacturing scale is not practically feasible, development of scale-down models that represent the performance of the commercial process is essential to achieve reliable process characterization. In this study, we describe a systematic approach to develop a bioreactor scale-down model and to characterize a cell culture process for recombinant protein production in CHO cells. First, a scale-down model using 2-L bioreactors was developed on the basis of the 2000-L commercial scale process. Profiles of cell growth, productivity, product quality, culture environments (pH, DO, pCO2), and level of metabolites (glucose, glutamine, lactate, ammonia) were compared between the two scales to qualify the scale-down model. The key operating parameters were then characterized in single-parameter ranging studies and an interaction study using this scale-down model. Appropriate operation ranges and acceptance criteria for certain key parameters were determined to ensure the success of process validation and the process performance consistency. The process worst-case condition was also identified through the interaction study. [source] Co-administration of the JAK inhibitor CP-690,550 and methotrexate is well tolerated in patients with rheumatoid arthritis without need for dose adjustmentBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 2 2010Stanley Cohen WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , CP-690,550 is a novel JAK inhibitor in development as a therapy for rheumatoid arthritis. , Methotrexate is the cornerstone of combination treatment for rheumatoid arthritis. , The safety and tolerability of co-administration of CP-690,550 with methotrexate have not been addressed to date. WHAT THIS STUDY ADDS , This study in patients with rheumatoid arthritis shows that there are no clinically relevant effects on the pharmacokinetics of either drug following short-term co-administration. , Co-administration of CP-690,550 and methotrexate was safe and well tolerated. AIMS To investigate the effects of methotrexate (MTX) on the pharmacokinetics (PK) of CP-690,550, a novel Janus kinase (JAK) inhibitor in development as a therapy for rheumatoid arthritis (RA), to determine the effects of multiple doses of CP-690,550 on the PK of MTX, and to evaluate the short-term safety and tolerability of co-administration of CP-690,550 and MTX. METHODS This was a fixed-dose drug,drug interaction study. Twelve patients diagnosed with RA for at least 6 months were enrolled in a Phase I, open-label study of the PK of multiple doses of CP-690,550 (30 mg b.i.d.) and single doses of MTX (15,25 mg per week). RESULTS All patients completed the study and were evaluated for PK and safety. CP-690,550 exposure was not affected by co-administration with MTX; AUC12 ratio (CP-690,550 + MTX/CP-690,550) was 103.06% [90% confidence interval (CI) 99.00, 107.29]. MTX exposure decreased by 10%; AUC12 ratio (CP-690,550 + MTX/MTX) was 89.53% (90% CI 77.38, 103.57), which was not considered clinically significant. Co-administration of CP-690,550 and MTX was safe and well tolerated. There were no serious adverse events or withdrawals from the study and there was no trend in the incidence or severity of adverse events across treatments. CONCLUSIONS Co-administration of CP-690,550 and MTX was safe and well tolerated. There was no clinically significant effect on the PK profile of either drug. Therefore, dose adjustments should not be required when co-administering CP-690,550 and MTX. [source] Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjectsACTA NEUROLOGICA SCANDINAVICA, Issue 4 2010L. Almeida Almeida L, Nunes T, Sicard E, Rocha J-F, Falcão A, Brunet J-S, Lefebvre M, Soares-da-Silva P. Pharmacokinetic interaction study between eslicarbazepine acetate and lamotrigine in healthy subjects. Acta Neurol Scand: 2010: 121: 257,264. © 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Objective,,, Anti-epileptic drugs are often used in combination. Both eslicarbazepine (main metabolite of eslicarbazepine acetate, ESL) and lamotrigine undergo conjugation with glucuronic acid, and both eslicarbazepine and its glucuronide and lamotrigine glucuronide undergo extensive renal elimination; therefore, there is a potential for interaction. This study investigated the interaction between ESL and lamotrigine in healthy subjects. Methods,,, Open-label study in two parallel groups of 16 healthy volunteers each. After an 8-day treatment with ESL or lamotrigine, ESL (1200 mg once-daily) and lamotrigine (150 mg once-daily) were co-administered for 19 days. Geometric mean ratios (GMR) and 90% confidence intervals (90% CI) for maximum plasma concentration (Cmax) and area under the plasma concentration,time curve in the dosing interval (AUC0,24) were calculated for eslicarbazepine (ESL active metabolite) and lamotrigine. Results,,, The Cmax and AUC0,24 GMR (90% CI) were, respectively, 95% (87,102%) and 96% (91,102%) for eslicarbazepine, and 88% (82,94%) and 86% (81,92%) for lamotrigine. The 90% CI of the Cmax and AUC0,24 GMR fell within the prespecified acceptance interval (80,125%) both for eslicarbazepine and lamotrigine. Conclusion,,, There was no significant pharmacokinetic interaction between ESL and lamotrigine in healthy subjects. Therefore, no dosage adjustment appears to be usually required in either lamotrigine or ESL when the drugs are co-administered. [source] | ||||||||||||||||||||||||||||