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Vivo Characterization (vivo + characterization)
Selected AbstractsIn vitro and in vivo characterization of TC-1827, a novel brain ,4,2 nicotinic receptor agonist with pro-cognitive activityDRUG DEVELOPMENT RESEARCH, Issue 1 2004Georg Andrees Bohme Abstract Nicotine activates specific receptors that are cation-permeable ionic channels located in the central and autonomous nervous systems, as well as at the neuromuscular junction. Administration of nicotine to animals and humans has been shown to enhance cognitive processes. However, side effects linked to the activation of peripheral nicotinic receptors limit the usefulness of nicotine for the treatment of cognitive disorders such as Alzheimer's disease (AD) or mild cognitive impairments (MCI). The synthesis and properties of TC-1827, a novel metanicotine derivative that activates brain ,4,2 nicotinic receptors is described. TC-1827 has high affinity for nicotine-labeled receptors in the cortex (Ki=34 nM), full-agonist intrinsic activity in ,4,2 -mediated neurotransmitter release studies in synaptosomes, and has no functional activity at nicotinic receptors in ganglionic or muscular cell lines. The compound enhances long-term potentiation in hippocampal slices, a form of synaptic plasticity thought to be involved in information storage at the cellular level. In vivo studies demonstrate that TC-1827 dose-dependently occupies thalamic nicotinic receptors labeled with [3H]-cytisine, increases cortical extracellular acetylcholine levels following oral administration, and enhances cognitive performance in rat and mice behavioral procedures of learning and memory. Pharmacokinetic studies in mice, rats, and monkeys indicated that TC-1827 has good oral absorption with a first pass effect resulting in bioavailabilities of 13,65% across dose/species. Cardiovascular safety studies indicate good cardiovascular tolerability for this compound. The present data demonstrate that TC-1827 is a selective and potent activator of brain ,4,2 nicotinic receptors and is a prototypical member of a new class of compounds with potential utility in the symptomatic treatment of cognitive disorders including AD and MCI. Drug Dev. Res. 62:26,40, 2004. © 2004 Wiley-Liss, Inc. [source] In vivo characterization of the angiotensin-(1,7)-induced dopamine and ,-aminobutyric acid release in the striatum of the ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2005Bart Stragier Abstract The effect of angiotensin (Ang)-1,7 on dopamine, ,-aminobutyric acid (GABA) and glutamate release in the striatum of the rat was examined using in vivo microdialysis. Ang-(1,7) was administered locally in the striatum through the microdialysis probe. At a concentration of 100 µm, Ang-(1,7) caused a significant increase in extracellular dopamine and GABA but had no effect on glutamate release. The Ang-(1,7)-induced dopamine release was blocked by EC33, an inhibitor of aminopeptidase A, an enzyme which converts Ang-(1,7) into Ang-(3,7), suggesting that this effect occurs after metabolism into Ang-(3,7). Indeed, administration of Ang-(3,7) (10,100 µm) into the striatum caused a more potent increase in the striatal dopamine release than Ang-(1,7). Because Ang-(3,7) is an inhibitor of insulin-regulated aminopeptidase (IRAP) and because Ang IV, another IRAP inhibitor, also causes a concentration-dependent increase in dopamine in the rat striatum, IRAP may be involved in this effect. In contrast, EC33 had no effect on the Ang-(1,7)-induced GABA increase but the GABA release was blocked by the putative AT1-7 receptor antagonist A779 (0.1 µm) and by the nitric oxide synthase inhibitor L-NAME (1 mm). These drugs could not block the effect of Ang-(1,7) on the striatal dopamine release suggesting that only the observed effects on GABA release are mediated by the AT1-7 receptor and/or are associated with a release of nitric oxide. [source] The synthesis of tritium labelled neurokinin-1 receptor ligandsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 2 2004Terence G. Hamill Abstract Radiolabelled neurokinin-1 (NK1) receptor antagonists 1b and 2b were required for in vitro/in vivo characterization to support the development of 1a and 2a as fluorine-18 labelled PET ligands. These tritium labelled compounds were synthesized from aryl iodide precursors giving the final tritiated tracers with specific activities of 28 (1b) and 14 (2b) Ci/mmol. Copyright © 2004 John Wiley & Sons, Ltd. [source] Thiomers in noninvasive polypeptide delivery: In vitro and in vivo characterization of a polycarbophil-cysteine/glutathione gel formulation for human growth hormoneJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2004Verena M. Leitner Abstract This study was aimed at investigating the potential of a new polycarbophil-cysteine (PCP-Cys)/glutathione (GSH) gel formulation to enhance the permeation of the model drug human growth hormone (hGH) across nasal mucosa in vitro and in vivo. The aqueous nasal gel contained PCP-Cys, GSH, and hGH in a final concentration of 0.3%, 0.5%, and 0.6% (m/v), respectively. In vitro permeation studies were performed in Ussing chambers on freshly excised bovine nasal mucosa using fluorescence-labeled dextran (molecular mass: 4.3 kDa; FD-4) and hGH (FITC-hGH). The release profile of FITC-hGH from the gel formulation and an unmodified PCP control formulation was determined. Furthermore, in vivo studies in rats were performed comparing the PCP-Cys/GSH/hGH gel with PCP/hGH control gel and physiological saline. The permeation of FD-4 and FITC-hGH across the nasal mucosa was improved two-fold and three-fold, respectively, in the presence of PCP-Cys/GSH. The PCP-Cys/GSH/hGH gel and the PCP/hGH control gel showed the same biphasic and matrix-controlled drug release. The nasal administration of the PCP-Cys/GSH/hGH gel formulation to rats resulted in a significantly increased and prolonged hGH plasma concentration,time profile versus unmodified PCP gel and physiological saline. According to these results, PCP-Cys gels might represent a promising new strategy for systemic nasal polypeptide delivery. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1682,1691, 2004 [source] Phase-contrast velocimetry with hyperpolarized 3He for in vitro and in vivo characterization of airflowMAGNETIC RESONANCE IN MEDICINE, Issue 6 2006Ludovic de Rochefort Abstract This paper describes a technique that combines radial MRI and phase contrast (PC) to map the velocities of hyperpolarized gases (3He) in respiratory airways. The method was evaluated on well known geometries (straight and U-shaped pipes) before it was applied in vivo. Dynamic 2D maps of the three velocity components were obtained from a 10-mm slice with an in-plane spatial resolution of 1.6 mm within 1 s. Integration of the in vitro through-plane velocity over the slice matched the input flow within a relative precision of 6.4%. As expected for the given Reynolds number, a parabolic velocity profile was obtained in the straight pipe. In the U-shaped pipe the three velocity components were measured and compared to a fluid-dynamics simulation so the precision was evaluated as fine as 0.025 m s,1. The technique also demonstrated its ability to visualize vortices and localize characteristic points, such as the maximum velocity and vortex-center positions. Finally, in vivo feasibility was demonstrated in the human trachea during inhalation. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] A multi-angular mass spectrometric view at cyclic nucleotide dependent protein kinases: In vivo characterization and structure/function relationshipsMASS SPECTROMETRY REVIEWS, Issue 4 2008Arjen Scholten Abstract Mass spectrometry has evolved in recent years to a well-accepted and increasingly important complementary technique in molecular and structural biology. Here we review the many contributions mass spectrometry based studies have made in recent years in our understanding of the important cyclic nucleotide activated protein kinase A (PKA) and protein kinase G (PKG). We both describe the characterization of kinase isozymes, substrate phosphorylation, binding partners and post-translational modifications by proteomics based methodologies as well as their structural and functional properties as revealed by native mass spectrometry, H/D exchange MS and ion mobility. Combining all these mass spectrometry based data with other biophysical and biochemical data has been of great help to unravel the intricate regulation of kinase function in the cell in all its magnificent complexity. © 2008 Wiley Periodicals, Inc. Mass Spec Rev 27: 331,353, 2008 [source] The essential neutral sphingomyelinase is involved in the trafficking of the variant surface glycoprotein in the bloodstream form of Trypanosoma bruceiMOLECULAR MICROBIOLOGY, Issue 6 2010Simon A. Young Summary Sphingomyelin is the main sphingolipid in Trypanosoma brucei, the causative agent of African sleeping sickness. In vitro and in vivo characterization of the T. brucei neutral sphingomyelinase demonstrates that it is directly involved in sphingomyelin catabolism. Gene knockout studies in the bloodstream form of the parasite indicate that the neutral sphingomyelinase is essential for growth and survival, thus highlighting that the de novo biosynthesis of ceramide is unable to compensate for the loss of sphingomyelin catabolism. The phenotype of the conditional knockout has given new insights into the highly active endocytic and exocytic pathways in the bloodstream form of T. brucei. Hence, the formation of ceramide in the endoplasmic reticulum affects post-Golgi sorting and rate of deposition of newly synthesized GPI-anchored variant surface glycoprotein on the cell surface. This directly influences the corresponding rate of endocytosis, via the recycling endosomes, of pre-existing cell surface variant surface glycoprotein. The trypanosomes use this coupled endocytic and exocytic mechanism to maintain the cell density of its crucial variant surface glycoprotein protective coat. TbnSMase is therefore genetically validated as a drug target against African trypanosomes, and suggests that interfering with the endocytic transport of variant surface glycoprotein is a highly desirable strategy for drug development against African trypanosomasis. [source] In vivo analysis of the post-natal development of normal mouse brain by DTINMR IN BIOMEDICINE, Issue 4 2007Pierre Larvaron Abstract The water diffusion characteristics of wild-type mouse brains have been studied in vivo by DTI to follow developmental changes. Here, axial (,//) and radial (,,) diffusivities and fractional anisotropy were measured from the fifth day of life (P5) and at three other post-natal ages (P12, P19 and P54). Magnetic resonance images were collected from a single sagittal slice in the middle of the two hemispheres; ROI were chosen in nine different structures of both grey and white matter. Fractional anisotropy (FA) from P5 onwards distinguished structures of both white and grey matter, even though myelination had yet to occur. Between P5 and P54, a significant increase in FA was observed in the genu of the corpus callosum due to a significant decrease in ,, whereas ,// remained stable. Many other significant variations of ,// and ,, were measured in different structures. They were substantially correlated with axon and myelin maturation which are responsible for the main evolutions of the brain during its post-natal development. These quantitative data show that in vivo characterization of the anatomy and microstructure of the normal mouse brain during development is possible. The normative data will greatly improve the characterization of abnormal development in the transgenic mouse brain. Copyright © 2006 John Wiley & Sons, Ltd. [source] The hydroxyproline-rich glycoprotein domain of the Arabidopsis LRX1 requires Tyr for function but not for insolubilization in the cell wallTHE PLANT JOURNAL, Issue 4 2010Christoph Ringli Summary Extensins, hydroxyproline-rich repetitive glycoproteins with Ser,Hyp4 motifs, are structural proteins in plant cell walls. The leucine-rich repeat extensin 1 (LRX1) of Arabidopsis thaliana is an extracellular protein with both a leucine-rich repeat and an extensin domain, and has been demonstrated to be important for cell-wall formation in root hairs. lrx1 mutants develop defective cell walls, resulting in a strong root hair phenotype. The extensin domain is essential for protein function and is thought to confer insolubilization of LRX1 in the cell wall. Here, in vivo characterization of the LRX1 extensin domain is described. First, a series of LRX1 extensin deletion constructs was produced that led to identification of a much shorter, functional extensin domain. Tyr residues can induce intra- and inter-molecular cross-links in extensins, and substitution of Tyr in the extensin domain by Phe led to reduced activity of the corresponding LRX1 protein. An additional function of Tyr (or Phe) is provided by the aromatic nature of the side chain. This suggests that these residues might be involved in hydrophobic stacking, possibly as a mechanism of protein assembly. Finally, modified LRX1 proteins lacking Tyr in the extensin domain are still insolubilized in the cell wall, indicating strong interactions of extensins within the cell wall in addition to the well-described Tyr cross-links. [source] Can we use diffusion MRI as a bio-marker of neurodegenerative processes?BIOESSAYS, Issue 11-12 2008Yaniv Assaf Magnetic resonance imaging (MRI) is an imaging technique with a rapidly expanding application range. This methodology, which relies on quantum physics and substance magnetic properties, is now being routinely used in the clinics and medical research. With the advent of measuring functional brain activity with MRI (functional MRI), this methodology has reached a larger section of the neuroscience community (e.g. psychologists, neurobiologists). In the past, the use of MRI as a biomarker or as an assay to probe tissue pathophysiological condition was limited. However, with the new applications of MRI: molecular imaging, contrast-enhanced imaging and diffusion imaging, MRI is turning into a powerful tool for in vivo characterization of tissue pathophysiology. This review focuses on the diffusion MRI. Although it only measures the averaged Brownian translational motion of water molecules, using different analysis schemes, one can extract a wide range of quantitative indices that represent tissue morphology and compartmentalization. Statistical and visualization routines help to relate these indices to biologically relevant measures such as cell density, water content and size distribution. The aim of this review is to shed light on the potential of this methodology to be used in biological research. To that end, this review is intended for the non-MRI specialists who wish to pursue biological research with this methodology. We will overview the current applications of diffusion MRI and its relation to cellular biology of brain tissue. BioEssays 30:1235,1245, 2008. © 2008 Wiley Periodicals, Inc. [source] Synthesis, radiolabeling and in vitro and in vivo characterization of a technetium-99m-labeled alpha-M2 peptide as a tumor imaging agentCHEMICAL BIOLOGY & DRUG DESIGN, Issue 6 2004S.M. Okarvi Abstract:, In an effort to develop a peptide-based radiopharmaceutical for the detection of breast cancer, we have prepared an analog of ,M2 peptide, modified to incorporate an N3S chelate system. Mercaptoacetyltriglycine (MAG)3 -derivatized ,M2 peptide was prepared by solid-phase synthesis and radiolabeled with 99mTc by an exchange method. In vitro cell-binding on human breast cancer cell lines, MDA-MB-231 and MCF-7, indicated the affinity and specificity of 99mTc-MAG3 - ,M2 toward breast cancer cells. Additionally, the radiolabeled peptide showed rapid internalization into human breast cancer cells. In vivo biodistribution in mice showed that the radiolabeled peptide cleared rapidly from the blood and most non-target tissues and was excreted significantly via the kidneys. Uptake of 99mTc-MAG3 - ,M2 in the tumor was moderate. The radiochemical and in vitro and in vivo characterization indicates that the radiolabeled peptide has certain favorable properties and it might be a useful radiopharmaceutical for the detection of breast cancer in vivo. [source] Transitions of serum albumin in patients with glomerulosclerosis ,in vivo' characterization by electrophoretic titration curvesELECTROPHORESIS, Issue 14 2006Maurizio Bruschi Abstract HSA functions as a physiological transporter of solutes and small molecules that induce structural transitions ,in vitro'. Analysis of these transitions requires prior purification of HSA that could introduce bias due to conformational changes. We utilized electrophoretic titration curves to describe a neutral to acid (N,A) transition of HSA directly in sera of seven patients with active focal segmental glomerulosclerosis (FSGS). The divergent electrophoretic profile of HSA was characterized by a shift in the range of pHs between 4.5 and 7.5 with an average variation of free electrophoretic mobility corresponding to loss of 1 positive charge in the pKa protonation range of histidyl residues and should involve domain I of HSA. ,In-gel' determination by maleimide-PEO2-biotin of free SH 34 of domain I showed inaccessibility of the dye at this site in pathological HSA and alkylation with the same complex induced N,A transition in normal HSA. Potential binders of free imidazoles such as Ca++ and/or of SH 34 such as NO were excluded on the basis of direct titration and studies on binding stimulation. This is the first report describing a transition of HSA directly ,in vivo', and the utilization of electrophoretic titration curves was critical to this purpose. This transition appears to be specific to FSGS and is unrelated to the nephrotic syndrome, Ca++ and NO binding. Spectroscopic analysis will elucidate the structural implication. [source] |