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Target Interactions (target + interaction)

Distribution by Scientific Domains

Life Sciences	60%

Selected Abstracts

Laser,target interaction during high-power pulsed laser deposition of superconducting thin films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007
Ranran Fang
Abstract We present a theoretical model to describe the high-power nanosecond pulsed laser ablation of multi-elemental oxide superconductors by considering both the vaporization effect and the plasma shielding effect. Using as an example a YBa2Cu3O7 target, the numerical solutions are obtained by solving the heat flow equations using a finite difference method. We obtain the time dependence of temperature, the transmitted intensity and the ablation rate of the target. The numerical results agree well with the experimental data and are much better than without considering the effects of vaporization and plasma shielding, which indicates that the two effects in high-power nanosecond laser ablation of superconductors must not be neglected. The present model will be helpful for the investigation of superconducting thin films prepared by pulsed laser deposition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Calretinin and calbindin D28k have different domain organizations

PROTEIN SCIENCE, Issue 1 2003
gorzata Palczewska
Abstract The domain organization of calretinin (CR) was predicted to involve all six EF-hand motifs (labeled I to VI) condensed into a single domain, as characterized for calbindin D28k (Calb), the closest homolog of calretinin. Unperturbed 1H,15N HSQC NMR spectra of a 15N-labeled calretinin fragment (CR III,VI, residues 100,271) in the presence of the unlabeled complimentary fragment (CR I,II, residues 1,100) show that these fragments do not interact. Size exclusion chromatography and affinity chromatography data support this conclusion. The HSQC spectrum of 15N-labeled CR is similar to the overlaid spectra of individual 15N-labeled CR fragments (CR I,II and CR III,VI), also suggesting that these regions do not interact within intact CR. In contrast to these observations, but in accordance with the Calb studies, we observed interactions between other CR fragments: CR I (1,60) with CR II,VI (61,271), and CR I,III (1,142) with CR IV,VI (145,271). We conclude that CR is formed from at least two independent domains consisting of CR I,II and CR III,VI. The differences in domain organization of Calb and CR may explain the specific target interaction of Calb with caspase-3. Most importantly, the comparison of CR and Calb domain organizations questions the value of homologous modeling of EF-hand proteins, and perhaps of other protein families. [source]

CE-ESI-MS/MS as a rapid screening tool for the comparison of protein,ligand interactions

ELECTROPHORESIS, Issue 7 2010
Thomas Hoffmann
Abstract In drug development, the combinatorial synthesis of drug libraries is common use, therefore efficient tools for the characterization of drug candidates and the extent of interaction between a drug and its target protein is a central question of analytical interest. While biological activity is tested today by enzyme assays, MS techniques attract more and more attention as an alternative for a rapid comparison of drug,target interactions. CE enables the separation of proteins and drug,enzyme complexes preserving their physiological activity in aqueous media. By hyphenating CE with ESI-MS/MS, the binding strength of enzyme inhibitors can be deduced from MS/MS experiments, which selectively release the inhibitor from the drug,target complex after CID. In this study, ,-chymotrypsin (CT), a serine protease, was chosen as a model compound. Chymostatin is a naturally occurring peptide aldehyde binding to CT through a hemiacetal bond and electrostatic interaction. First, a CE separation was developed, which allows the analysis of ,-CT and a chymotrypsin,chymostatin complex under MS-compatible conditions. The use of neutral-coated CE capillaries was mandatory to reduce analyte,wall interactions. ESI-quadrupole ion trap-MS was worked out to demonstrate the selective drug release after CID. Fragmentation of the drug,enzyme complex was monitored in dependence from the excitation energy in the ion trap, leading to the V50 voltage that enables 50% complex fragmentation as a reference value for chymotrypsin,chymostatin complex. A stable CE-ESI-MS/MS setup was established, which preserves the drug,enzyme complexes during ionization,desolvation processes. With this optimized setup, different CT inhibitors could be investigated and compared. [source]

Afferent,target interactions during olivocerebellar development: transcommissural reinnervation indicates interdependence of Purkinje cell maturation and climbing fibre synapse elimination

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2005
Ann M. Lohof
Abstract We have used a model of postlesional reinnervation to observe the interactions between synaptic partners during neosynaptogenesis to determine how the developmental states of the pre- and postsynaptic cells influence circuit maturation. After unilateral transection of the neonatal rat olivocerebellar pathway (pedunculotomy), axons from the remaining ipsilateral inferior olive grow into the denervated hemicerebellum and develop climbing fibre (CF) terminal arbors on Purkinje cells (PCs) at a later stage of development than normal. However, the significance of delayed CF-PC interactions on subsequent circuit maturation remains poorly defined. To examine this question, we recorded CF-induced currents in PCs and analysed PC morphology during the first two postnatal weeks in control animals and following left unilateral inferior cerebellar pedunculotomy on postnatal day (P)3. Our results show that transcommissural olivary axons multiply-reinnervate PCs in the denervated hemisphere over 4 days following pedunculotomy. Each PC received fewer CFs than did age-matched controls and the maximal multi-reinnervation was reached on P7, 2 days later than in controls. Consequently, the onset of CF synapse elimination in reinnervated PCs was delayed, but then proceeded in parallel with controls so that all PCs were monoinnervated by P15. Furthermore, reinnervated PCs had delayed dendritic maturation and subsequent dendritic abnormalities consistent with the role of CF innervation in PC dendritic growth. Thus, within the olivocerebellar system, our data suggest that target neurons depend upon sufficient afferent investment arriving at the correct time for their normal development, and maturation of the target neuron regulates afferent selection and therefore circuit maturation. [source]

Post-lesion transcommissural growth of olivary climbing fibres creates functional synaptic microzones

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003
Izumi Sugihara
Abstract In the adult mammalian central nervous system, reinnervation and recovery from trauma is limited. During development, however, postlesion plasticity may generate alternate paths, providing models to investigate reinnervating axon,target interactions. After unilateral transection of the neonatal rat olivocerebellar path, axons from the ipsilateral inferior olive grow into the denervated hemicerebellum and develop climbing fibre (CF)-like arbors on Purkinje cells (PCs). However, the synaptic function and extent of PC reinnervation remain unknown. In adult rats pedunculotomized on postnatal day 3 the morphological and electrophysiological properties of reinnervating olivocerebellar axons were studied, using axonal reconstruction and patch-clamp PC recording of CF-induced synaptic currents. Reinnervated PCs displayed normal CF currents, and the frequency of PC reinnervation decreased with increasing laterality. Reinnervating CF arbors were predominantly normal but 6% branched within the molecular layer forming smaller secondary arbors. CFs arose from transcommissural olivary axons, which branched extensively near their target PCs to produce on average 36 CFs, which is six times more than normal. Axons terminating in the hemisphere developed more CFs than those terminating in the vermis. However, the precise parasagittal microzone organization was preserved. Transcommissural axons also branched, although to a lesser extent, to the deep cerebellar nuclei and terminated in a distribution indicative of the olivo-cortico-nuclear circuit. These results show that reinnervating olivocerebellar axons are highly plastic in the cerebellum, compensating anatomically and functionally for early postnatal denervation, and that this reparation obeys precise topographic constraints although axonal plasticity is modified by target (PC or deep nuclear neurons) interactions. [source]