Functional characterisation of P2 purinoceptors in PC12 cells by measurement of radiolabelled calcium influx

The aim of this study was to determine whether 45Ca2+ influx could be used as a quantitative measure of channel activation for functional characterisation of P2X purinoceptors in cell lines. In undifferentiated PC12 cells, grown in suspension, ATP (EC50 = 45 microM), ATP gamma S (EC50 = 50 microM) and 2-meSATP (EC50 = 81 microM) but not alpha beta meATP (1 mM) stimulated 45Ca2+ influx 2-5 fold. This effect did not appear to be due to activation of P2U or P2Y purinoceptors since 1 mM UTP, ADP or ADP beta S did not produce any significant effect. Similarly, the effects of ATP were not apparently mediated through activation of P2Z purinoceptors since dibenzylATP behaved as a weak (EC50 = 191 microM) partial agonist (Maximal effect 29.5% of ATP maximum) and there was no detectable ATP-stimulated ethidium bromide uptake in the PC12 cells. ATP-stimulated 45Ca2+ influx was not affected by nifedipine suggesting that it was not secondary to activation of L-type calcium channels and rather reflected influx through a P2X purinoceptor present in these cells. The ATP-stimulated 45Ca2+ influx could be reduced by monovalent cations, presumably as a result of direct competition for influx through the cation channel, with the following rank order of potency:- guanidinium (EC50 = 16 mM) > sodium > Tris > choline > N-methyl-D-glucamine = sucrose). A number of P2 purinoceptor antagonists inhibited ATP-stimulated 45Ca2+ influx. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (3-300 microM), pyridoxal 5-phosphate (3-300 microM) and d-tubocurarine (30-300 microM) produced an insurmountable antagonism of responses to ATP, with no marked change in agonist EC50. Suramin (100-300 microM) and cibacron blue (30-300 microM) produced a surmountable antagonism while DIDS (4,4'-diisothiocyanatostilbene-2,2'disulfonic acid) only antagonised responses to ATP at concentrations in excess of 300 microM. The general properties of the P2X purinoceptor population identified in these cells were consistent with them being P2X2 purinoceptors. These findings suggest that ATP-stimulated 45Ca2+ influx may be used as a reliable and quantitative functional assay for characterisation of P2X purinoceptor subtypes in cell lines.     

Machine intelligence-driven classification of cancer patients-derived extracellular vesicles using fluorescence correlation spectroscopy: results from a pilot study

Neural Computing and Applications - Patient-derived extracellular vesicles (EVs) that contains a complex biological cargo is a valuable source of liquid-biopsy diagnostics to aid in early...     

Grand rounds in proteomics at the FDA white oak, silver spring, MD, USA, april 3, 2007

The application of proteomics in drug development could be a major source of novel biomarkers to improve the efficacy and safety of new drugs. Training of US Food and Drug Administration (FDA) reviewers on current applications of proteomics is important for the future review of proteomic data. A Grand Rounds in Proteomics was held on April 3, 2007 at the FDA in White Oak, Silver Spring, MD, USA. The goal of this activity was to contribute to reviewer training as well as to generate discussions regarding the readiness of proteomic platforms in drug development, similar in scope to applications in genomics and metabolomics. Several speakers from industry and academia presented data on proteomic applications in drug development (meeting agenda available in the Supporting Information). An additional goal of this meeting was to encourage proteomic data submissions within the Voluntary eXploratory Data Submissions (VXDS) at the FDA. VXDS meetings represent key venues for exchange between the FDA and sponsors of scientific and clinical data on exploratory biomarkers. The FDA has received a limited number of VXDS submissions containing proteomic data. This meeting was an opportunity to identify possible areas in proteomics where future VXDS submissions may be received. Voluntary submissions have been transformed into regulatory submissions in genomics, and a similar path may also be followed by proteomic data in the future. Proteomic biomarkers may also be suitable for submission to the Pilot Process for Biomarker Qualification at the FDA.     

Construction of an instrument to measure student information and communication technology skills,experience and attitudes to e-learning

Over the past 20 years self-report measures of healthcare students’ information and communication technology skills have been developed with limited validation. Furthermore, measures of student experience of e-learning emerged but were not repeatedly used with diverse populations. A psychometric approach with five phases was used to develop and test a new self-report measure of skills and experience with information and communication technology and attitudes to computers in education. Phase 1: Literature review and identification of key items. Phase 2: Development and refinement of items with expert panel (n = 16) and students (n = 3) to establish face and content validity. Phase 3: Pilot testing of draft instrument with graduate pre-registration nursing students (n = 60) to assess administration procedures and acceptability of the instrument. Phase 4: Test–retest with further sample of graduate pre-registration nursing students (n = 70) tested stability and internal consistency. Phase 5: Main study with pre-registration nursing students (n = 458), further testing of internal consistency. The instrument proved to have moderate test–retest stability and the sub-scales had acceptable internal consistency. When used with a larger, more diverse population the psychometric properties were more variable. Further work is needed to refine the instrument with specific reference to possible cultural and linguistic response patterns and technological advances.     

A cross-country model of contextual factors impacting cloud computing adoption at universities in sub-Saharan Africa

Cloud computing is a new computing paradigm that is revolutionizing the way we access and use computer infrastructure and services. Universities in developing countries lag behind their Western counterparts due to lack of cutting edge technology required for teaching, collaboration, and research. The purpose of this study was to investigate the factors that impact diffusion, adoption, and usage of cloud computing at universities in sub-Saharan Africa (SSA). An adoption model was developed focusing on contextual factors and constructs from two technology adoption theories. Structural equation modelling was used for data analysis and model validation. Results from 355 valid responses to a survey of information and communication technology (ICT) experts and decision makers at universities in SSA indicated that socio-cultural factors, results demonstrability, usefulness, and data security significantly impact their propensity to recommend adoption of cloud computing in the universities. The implications of the findings and practical contributions are discussed.     

Escaping in digital games: The relationship between playing motives and addictive tendencies in males

Problematic playing behaviour in terms of addiction is well known to be associated with specific traits (e.g., self-esteem) and weak social settings (e.g., negative relationships). What remains unclear is the impact of playing motives on addictive tendencies. We investigated how playing motives were related to problematic playing behaviour. Using ratings indicating explicit motives and response latencies indicating the activation of implicit motives, we investigated Yee’s (2006) three main playing motives: social interaction, achievement, and immersion. All three implicit motives were found to be highly activated among problematic players while only explicit immersion was judged as less important by non-problematic and excessive players. In addition, implicit immersion together with explicit immersion and playing hours were found to be strong predictors for problematic playing behaviour. We discuss motives, especially immersion, as possible risk factors for addictive tendencies when motives become internalised and therefore automatically activated by thoughts about digital games.     

Control strategies on stable manifolds for energy-efficient swing-ups of double pendula

Optimal control problems for mechanical systems often arise in technical applications. To find solutions with minimal control effort, the system’s natural, uncontrolled dynamics can be used. Promising candidates to be considered for energy-efficient trajectories are highly dynamic, but uncontrolled motions on (un)stable manifolds of equilibria. In this contribution, we propose a control strategy for mechanical systems which sequences uncontrolled trajectories on (un)stable manifolds with short control manoeuvres to design a feedforward control. In particular, we present optimal swing-up solutions for a double pendulum which are based on trajectories on the stable manifold of the pendulum’s up–up equilibrium. To demonstrate the advantages of our approach compared to a black-box optimisation, we perform a post-optimisation with the optimal control sequence as an initial guess. The numerical results are evaluated in a simulation environment for the double pendulum on a cart and applied to a real test rig.