57 research outputs found
Construction, theory, and practical considerations for using self-referencing of Ca2+-selective microelectrodes for monitoring extracellular Ca2+ gradients
No full textAuthor Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Methods in Cell Biology 99 (2010): 91-111, doi:10.1016/B978-0-12-374841-6.00004-9.Ca2+ signaling in the extra- and intracellular domains is linked to Ca2+ transport across the plasma membrane. Non-invasive monitoring of these resulting extracellular Ca2+ gradients with self-referencing of Ca2+-selective microelectrodes is used for studying Ca2+ signaling across Kingdoms. The quantitated Ca2+ flux enables comparison with changes to intracellular [Ca2+] measured with other methods and determination of Ca2+ transport stoichiometry. Here we review the construction of Ca2+-selective microelectrodes, their physical characteristics and their use in self-referencing mode to calculate Ca2+ flux. We also discuss potential complications when using them to measure Ca2+ gradients near the boundary layers of single cells and tissues.NIH:NCRR grant P41 RR00139
Dielectrophoretic tweezer for isolating and manipulating target cells
No full textThe ability to isolate and accurately position single cells in three dimensions is becoming increasingly important in many areas of biological research. The authors describe the design, theoretical modelling and testing of a novel dielectrophoretic (DEP) tweezer for picking out and relocating single target cells. The device is constructed using facilities available in most electrophysiology laboratories, without the requirement of sophisticated and expensive microfabrication technology, and offers improved practical features over previously reported DEP tweezer designs. The DEP tweezer has been tested using transfected HEI-193 human schwannoma cells, with visual identification of the target cells being aided by labelling the incorporated gene product with a green fluorescent protei
Mitochondrial metabolism reveals a functional architecture in intact islets of Langerhans from normal and diabetic Psammomys obesus
No full textThe cells within the intact islet of Langerhans function as a metabolic syncytium, secreting insulin in a coordinated and oscillatory manner in response to external fuel. With increased glucose, the oscillatory amplitude is enhanced, leading to the hypothesis that cells within the islet are secreting with greater synchronization. Consequently, non-insulin-dependent diabetes mellitus (NIDDM; type 2 diabetes)-induced irregularities in insulin secretion oscillations may be attributed to decreased intercellular coordination. The purpose of the present study was to determine whether the degree of metabolic coordination within the intact islet was enhanced by increased glucose and compromised by NIDDM. Experiments were performed with isolated islets from normal and diabetic Psammomys obesus. Using confocal microscopy and the mitochondrial potentiometric dye rhodamine 123, we measured mitochondrial membrane potential oscillations in individual cells within intact islets. When mitochondrial membrane potential was averaged from all the cells in a single islet, the resultant waveform demonstrated clear sinusoidal oscillations. Cells within islets were heterogeneous in terms of cellular synchronicity (similarity in phase and period), sinusoidal regularity, and frequency of oscillation. Cells within normal islets oscillated with greater synchronicity compared with cells within diabetic islets. The range of oscillatory frequencies was unchanged by glucose or diabetes. Cells within diabetic (but not normal) islets increased oscillatory regularity in response to glucose. These data support the hypothesis that glucose enhances metabolic coupling in normal islets and that the dampening of oscillatory insulin secretion in NIDDM may result from disrupted metabolic coupling. <br/
Modelli letterari, eterodossia e autocensura nelle antologie epistolari : il primo libro delle Lettere volgari (Venezia, 1542)
No full textThis essay analyze anthologies of letters, et particularly the first edition of Lettere volgari (Venezia, Paolo Manuzio, 1542), because – unlike the collections of letters of well-known authors– these needed to be legitimised from a publishing point of view, as was demonstrated by the dedicatory epistles which provide indication of the objectives of these anthologies and on how they should be used by readers. The purpose of these epistolary collections was not definitely limited to the function of models for “good writing”. Indeed, if we stress only this aspect there is the risk of seeing only the “normalizing” aspects in the use of the Italian vernacular in a practice (the epistolary mode) which was particularly useful and widespread at various social levels. In fact in overestimating this aspect there is the risk of not understanding the reasons of the extraordinary publishing success. For a variety of reasons, this success was due not only to the practical use to which these books were destined. First of all, because the reader made a quite different use of the text from the one proposed by the publisher. Furthermore, these anthologies were not structured for a comfortable use; they had no subject indexes (which instead we find in books for Secretaries). The books are presented as a succession of texts on the most varied topics, which could have been used to produce other letters, but which at the same time could be read as we read any literary text, for the pleasure and the curiosity of grasping the relationships between well-known individuals (the senders and the recipients of the letters included literary figures, publishers, well-known bishops and cardinals, politicians and sovereigns), to discover the opinion of a famous author on a given work, or to have information on the religious climate and the tensions which touched men who followed up heterodox doctrines. Through some of these anthologies it is possible to reconstruct a circuit of relationships and personal relations based on common intellectual and sometime also religious experiences. As has been pointed out by studies by Anne Jacobson Schutte and Paolo Simoncelli, some of these anthologies, starting from the highly successful Lettere volgari di diversi nobilissimi huomini (Venice: Manuzio, 1542), contained letters which reflected heterodox doctrines
Resistant Hypertension Revisited: Definition And True Prevalence
No full text[No abstract available]3271546Smith, S.M., Gong, Y., Handberg, E., Messerli, F.H., Bakris, G.L., Ahmed, A., Predictors and outcomes of resistant hypertension among patients with coronary artery disease and hypertension (2014) J Hypertens, 32, pp. 635-643Pepine, C.J., Handberg, E.M., Cooper-Dehoff, R.M., Marks, R.G., Kowey, P., Messerli, F.H., A calcium antagonist vs a noncalcium antagonist hypertension treatment strategy for patients with coronary artery disease: The International Verapamil-Trandolapril Study (INVEST): A randomized controlled trial. (2003) JAMA, 290, pp. 2805-2816Julius, S., Kjeldsen, S.E., Brunner, H., Hansson, L., Platt, F., Ekman, S., VALUE trial: Long-termblood pressure trends in 13,449 patients with hypertension and high cardiovascular risk (2003) Am J Hypertens, 16, pp. 544-548Furberg, C.D., Wright, J.T., Davis, B.R., Cutler, J.A., Alderman, M., Black, H., Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) (2002) JAMA, 288, pp. 2981-2997Gupta, A.K., Nasothimiou, E.G., Chang, C.L., Sever, P.S., Dahlof, B., Poulter, N.R., Investigators A. Baseline predictors of resistant hypertension in the Anglo-Scandinavian Cardiac Outcome Trial (ASCOT): A risk score to identify those at high-risk (2011) J Hypertens, 29, pp. 2004-2013Black, H.R., Elliott, W.J., Grandits, G., Grambsch, P., Lucente, T., White, W.B., Principal results of the Controlled Onset Verapamil Investigation of Cardiovascular End Points (CONVINCE) Trial (2003) JAMA, 289, pp. 2073-2082Calhoun, D.A., Jones, D., Textor, S., Goff, D.C., Murphy, T.P., Toto, R.D., Resistant hypertension: Diagnosis, evaluation, and treatment. A scientific statement from the american heart association professional education committee of the council for high blood pressure research (2008) Hypertension, 51, pp. 1403-1419Garg, J.P., Elliott, W.J., Folker, A., Izhar, M., Black, H.R., Serv, R.U.H., Resistant hypertension revisited: A comparison of two university-based cohorts (2005) Am J Hypertens, 18, pp. 619-626Acelajado, M.C., Pisoni, R., Dudenbostel, T., Dell'Italia, L.J., Cartmill, F., Zhang, B., Refractory hypertension: Definition, prevalence, and patient characteristics (2012) J Clin Hypertens, 14, pp. 7-1
Maximum power point tracking under realistic operating conditions
No full textThe process of tracking the Maximum Power Point (MPP), known as MPPT, becomes problematic under realistic operating conditions due to the potential for there to be more than one local maxima. A very detailed physics based model has been developed for a PV module (in this application a PV roof tile) using the Orcad platform for PSpice. This model is unusual in that it properly represents partial module shading and cell temperature variation. The PV roof tile, based on polycrystalline silicon cells, comprises 18 series-connected cells. In the model, each cell is represented by a standard two-diode sub-model, for which different levels of radiation and cell temperature can be simulated to obtain a realistic overall I-V characteristic for the module. The model can be extended to model any reasonable number of PV roof tiles wired in series and parallel to form a roof array. The IV characteristics calculated in this way using PSpice will be validated using an outdoor PV roof test system located at the University of Strathclyde, Glasgow
Spatial manipulation of cells and organelles using single electrode dielectrophoresis
No full textAuthor Posting. © Author(s), 2012. This article is posted here by permission of Informa Healthcare USA, for personal use, not for redistribution. The definitive version was published in BioTechniques 52 (2012): 39-43, doi:10.2144/000113802.The selection, isolation, and accurate positioning of single cells in three dimensions are increasingly desirable in many areas of cell biology and tissue engineering. We describe the application of a simple and low cost dielectrophoretic device for picking out and relocating single target cells. The device consists of a single metal electrode and an AC signal generator. It does not require microfabrication technologies or sophisticated electronics. The dielectrophoretic manipulator also discriminates between live and dead cells and is capable of redistributing intracellular organelles.This research was funded by NIH-NCRR grant P41 RR001395 and supported by The Eugene and Millicent Bell Fellowship Fund in Tissue Engineering, the Hermann Foundation Research Development Fund Award, the Dennis and Alix Robinson Memorial, and the MBL Bell Center, grant GM092374.2012-07-0
Schistosoma mansoni P-glycoprotein levels increase in response to praziquantel exposure and correlate with reduced praziquantel susceptibility.
No full textOne potential physiological target for new antischistosomals is the parasite's system for excretion of wastes and xenobiotics. P-glycoprotein (Pgp), a member of the ATP-binding-cassette superfamily of proteins, is an ATP-dependent efflux pump involved in transport of toxins and xenobiotics from cells. In vertebrates, increased expression of Pgp is associated with multidrug resistance in tumor cells. Pgp may also play a role in drug resistance in helminths. In this report, we examine the relationship between praziquantel (PZQ), the current drug of choice against schistosomiasis, and Pgp expression in Schistosoma mansoni. We show that levels of RNA for SMDR2, a Pgp homolog from S. mansoni, increase transiently in adult male worms following exposure to sub-lethal concentrations (100-500 nM) of PZQ. A corresponding, though delayed, increase in anti-Pgp immunoreactive protein expression occurs in adult males following exposure to PZQ The level of anti-Pgp immunoreactivity in particular regions of adult worms also increases in response to PZQ Adult worms from an Egyptian S. mansoni isolate with reduced sensitivity to PZQ express increased levels of SMDR2 RNA and anti-Pgp-immunoreactive protein, perhaps indicating a role for multidrug resistance proteins in development or maintenance of PZQ resistance
Corpus pragmatics /
No full textThis Element discusses the challenges and opportunities that different types of corpora offer for the study of pragmatic phenomena. The focus lies on a hands-on approach to methods and data that provides orientation for methodological decisions. In addition, the Element identifies areas in which new methodological developments are needed in order to make new types of data accessible for pragmatic research. Linguistic corpora are currently undergoing diversification. While one trend is to move towards increasingly large corpora, another trend is to enhance corpora with more specialised and layered annotation. Both these trends offer new challenges and opportunities for the study of pragmatics. This volume provides a practical overview of state-of-the-art corpus-pragmatic methods in relation to different types of corpus data, covering established methods as well as innovative approaches. This title is also available as Open Access on Cambridge Core.Title from publisher's bibliographic system (viewed on 24 Feb 2023).This Element discusses the challenges and opportunities that different types of corpora offer for the study of pragmatic phenomena. The focus lies on a hands-on approach to methods and data that provides orientation for methodological decisions. In addition, the Element identifies areas in which new methodological developments are needed in order to make new types of data accessible for pragmatic research. Linguistic corpora are currently undergoing diversification. While one trend is to move towards increasingly large corpora, another trend is to enhance corpora with more specialised and layered annotation. Both these trends offer new challenges and opportunities for the study of pragmatics. This volume provides a practical overview of state-of-the-art corpus-pragmatic methods in relation to different types of corpus data, covering established methods as well as innovative approaches. This title is also available as Open Access on Cambridge Core
Physiological and pharmacological characterizations of the larval Anopheles albimanus rectum support a change in protein distribution and/or function in varying salinities
No full textIon regulation is a biological process crucial to the survival of mosquito larvae and a major organ responsible for this regulation is the rectum. The recta of anopheline larvae are distinct from other subfamilies of mosquitoes in several ways, yet have not yet been characterized extensively. Here we characterize the two major cell types of the anopheline rectum, DAR and non-DAR cells, using histological, physiological, and pharmacological analyses. Proton flux was measured at the basal membrane of 2%- and 50%-artificial sea water-reared An. albimanus larvae using self-referencing ion-selective microelectrodes, and the two cell types were found to differ in basal membrane proton flux. Additionally, differences in the response of that flux to pharmacological inhibitors in larvae reared in 2% versus 50% ASW indicate changes in protein function between the two rearing conditions. Finally, histological analyses suggest that the non-DAR cells are structurally suited for mediating ion transport. These data support a model of rectal ion regulation in which the non-DAR cells have a resorptive function in freshwater-reared larvae and a secretive function in saline water-reared larvae. In this way, anopheline larvae may adapt to varying salinitie
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