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Find video protocols related to scientific articles indexed in Pubmed.
Do Dissolving Objects Converge to a Universal Shape?
Langmuir
PUBLISHED: 11-20-2014
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Surprisingly, macroscopic objects such as melting ice cubes and growing stalactites approach non-intuitive geometric ideals. Here we investigate the shape of dissolving cylinders in a large volume of water. The cylinders are oriented vertically and consist of amorphous glucose or polyethylene glycol. The dissolution causes density differences in the surrounding fluid, which induce gravity-driven convection downwards along the object. The resulting concentration gradient shapes the cylinder according to fast dissolution at the tip and slow dissolution at the base. The contour of the object approaches a power law of the form z ? R(2) where z is the vertical distance from the tip and R is the corresponding radius. We suggest that this paraboloidal shape is the geometric attractor for the dissolution of non-crystalline objects in the presence of gravity.
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A Pneumocyte-macrophage Paracrine Lipid Axis Drives the Lung Toward Fibrosis.
Am. J. Respir. Cell Mol. Biol.
PUBLISHED: 11-20-2014
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Lipid-laden macrophages "foam cells" are observed in the lungs of patients with fibrotic lung disease but their contribution to disease pathogenesis remains unexplored. Here, we demonstrate that fibrosis induced by bleomycin, silica dust, or thoracic radiation promotes early and sustained accumulation of foam cells in the lung. In the bleomycin model, we show that foam cells arise from neighboring alveolar epithelial type II cells (ATII), which respond to injury by dumping lipids into the distal airspaces of the lungs. We demonstrate that oxidized phospholipids accumulate within alveolar macrophages (AM) after bleomycin injury, and that murine and human AMs treated with oxidized phosphatidylcholine (OxPc) become polarized along an M2 phenotype and display enhanced production of TGF-?1. The direct instillation of OxPc into the mouse lung induces foam cell formation and triggers a severe fibrotic reaction. Further, we show that reducing pulmonary lipid clearance by targeted deletion of the lipid efflux transporter ABCG1 increases foam cell formation and worsens lung fibrosis after bleomycin. Conversely, we found that treatment with GM-CSF attenuates fibrotic responses, at least in part through its ability to decrease AM lipid accumulation. In summary, this work describes a novel mechanism leading to foam cell formation in the mouse lung and suggests that strategies aimed at blocking foam cell formation might be effective for treating fibrotic lung disorders.
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Significance of Main Pulmonary Artery Dilation on Imaging Studies.
Ann Am Thorac Soc
PUBLISHED: 11-20-2014
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Proper and early identification of patients whom harbour serious occult illness is the first step in developing a disease management strategy. Identification of illnesses through the use of non-invasive techniques provides assurance of patient safety and is ideal. Pulmonary artery dilation is easily measured non-invasively and it is usually caused by pulmonary hypertension. The clinician should be able to thoroughly assess the significance of pulmonary artery dilation in each individual patient. This involves knowledge of the ability of pulmonary artery dilation to accurately predict pulmonary hypertension, understand the wide differential diagnosis of causes of pulmonary artery dilation, and revere its life threatening complications. We found that although pulmonary artery dilation is suggestive of pulmonary hypertension, data remains inconclusive in regards to its ability to accurately predict pulmonary hypertension. Further large-scale studies are needed to specifically test its clinical significance. At this point data is insufficient to place pulmonary artery dilation into a pulmonary hypertension risk-score equation. Here we review the causes and complications of pulmonary artery dilation, define normal and abnormal pulmonary artery measurements and summarize the data linking its association to pulmonary hypertension while suggesting an algorithm designed to assist clinicians in patient work-up after recognizing pulmonary artery dilation.
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Structure and function of ?-conotoxins, peptide-based sodium channel blockers with analgesic activity.
Future Med Chem
PUBLISHED: 11-19-2014
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?-Conotoxins block voltage-gated sodium channels (VGSCs) and compete with tetrodotoxin for binding to the sodium conductance pore. Early efforts identified µ-conotoxins that preferentially blocked the skeletal muscle subtype (NaV1.4). However, the last decade witnessed a significant increase in the number of µ-conotoxins and the range of VGSC subtypes inhibited (NaV1.2, NaV1.3 or NaV1.7). Twenty µ-conotoxin sequences have been identified to date and structure-activity relationship studies of several of these identified key residues responsible for interactions with VGSC subtypes. Efforts to engineer-in subtype specificity are driven by in vivo analgesic and neuromuscular blocking activities. This review summarizes structural and pharmacological studies of µ-conotoxins, which show promise for development of selective blockers of NaV1.2, and perhaps also NaV1.1,1.3 or 1.7.
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Computational approaches for designing potent and selective analogs of peptide toxins as novel therapeutics.
Future Med Chem
PUBLISHED: 11-19-2014
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Peptide toxins provide valuable therapeutic leads for many diseases. As they bind to their targets with high affinity, potency is usually ensured. However, toxins also bind to off-target receptors, causing potential side effects. Thus, a major challenge in generating drugs from peptide toxins is ensuring their specificity for their intended targets. Computational methods can play an important role in solving such design problems through construction of accurate models of receptor-toxin complexes and calculation of binding free energies. Here we review the computational methods used for this purpose and their application to toxins targeting ion channels. We describe ShK and HsTX1 toxins, high-affinity blockers of the voltage-gated potassium channel Kv1.3, which could be developed as therapeutic agents for autoimmune diseases.
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The Stability of the Guanine Endoperoxide Intermediate: A Computational Challenge for Density Functional Theory.
J Phys Chem A
PUBLISHED: 11-19-2014
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The addition of singlet molecular oxygen 1O2 onto guanine is a most important and deleterious reaction in biological damage. We assess the efficiency of density functional theory for evaluating the respective stabilities of two intermediates that can form upon 1O2 addition: a charge-separated adduct with a peroxide anion at the C8 position of guanine, and the corresponding cyclic endoperoxide across the 4,8-bond of the imidazole ring. The reference post Hartree-Fock SCS-MP3/aug-cc-pVTZ//MP2/DZP++ level of theory provides an unambiguous assignment in favor of the endoperoxide intermediate, based on implicitely solvated structures, by -8.0 kcal.mol-1. This value is taken as the reference for a systematic and extended benchmarck performed on a representative set of 65 different exchange-correlation functionals. While B3LYP remains commonly used for studying oxidative DNA lesions, we prove that the stability of the peroxide anion is overestimated by this functional, but also by other commonly used exchange-correlation functionals. The significant error (ca. +3 kcal.mol-1) arises from overdelocalization but also from the description of the dynamic correlation by the density functional. The significantly improved performance of several recently proposed functionals, including range-separated hybrids such as LC-BLYP, is outlined. We believe that our results will be of great help to further studies on the versatile chemistry of singlet oxygen-induced DNA damage, where complex reaction mechanisms are required to be depicted at a quantum level.
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Dicarba Analogues of ?-Conotoxin RgIA. Structure, Stability and Activity at Potential Pain Targets.
J. Med. Chem.
PUBLISHED: 11-14-2014
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?-Conotoxin RgIA is an antagonist of the ?9?10 nicotinic acetylcholine receptor (nAChR) subtype and also inhibits high voltage-activated N-type calcium channel currents. RgIA has therapeutic potential for the treatment of pain but reduction of the disulfide bond framework under physiological conditions represents a potential liability for clinical applications. We synthesized four RgIA analogues that replaced native disulfide pairs with non-reducible dicarba bridges. Solution structures were determined by NMR, activity assessed against biological targets and stability evaluated in human serum. [3,12]-dicarba analogues retained inhibition of ACh-evoked currents at ?9?10 nAChRs but not N-type calcium channel currents, whereas [2,8]-dicarba analogues displayed the opposite pattern of selectivity. The [2,8] dicarba RgIA analogues were effective in HEK293 cells stably expressing human Cav2.2 channels and transfected with human GABAB receptors. The analogues also exhibited improved serum stability over the native peptide. These selectively acting dicarba analogues may represent mechanistic probes to explore analgesia-related biological receptors.
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Antibiotic Use and Associated Factors in Patients with Dementia: A Systematic Review.
Drugs Aging
PUBLISHED: 11-12-2014
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Infections frequently occur in patients with dementia and antibiotics are often prescribed, but may also be withheld.
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Structure and Dynamics of Apical Membrane Antigen 1 from Plasmodium falciparum FVO.
Biochemistry
PUBLISHED: 11-01-2014
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Apical membrane antigen 1 (AMA1) interacts with RON2 to form a protein complex that plays a key role in the invasion of host cells by malaria parasites. Blocking this protein-protein interaction represents a potential route to controlling malaria and related parasitic diseases, but the polymorphic nature of AMA1 has proven to be a major challenge to vaccine-induced antibodies and peptide inhibitors exerting strain-transcending inhibitory effects. Here we present the X-ray crystal structure of AMA1 domains I and II from Plasmodium falciparum strain FVO. We compare our new structure to those of AMA1 from P. falciparum 3D7 and Plasmodium vivax. A combination of normalized B factor analysis and computational methods has been used to investigate the flexibility of the domain I loops and how this correlates with their roles in determining the strain specificity of human antibody responses and inhibitory peptides. We also investigated the domain II loop, a key region involved in inhibitor binding, by comparison of multiple AMA1 crystal structures. Collectively, these results provide valuable insights that should contribute to the design of strain-transcending agents targeting P. falciparum AMA1.
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Hemifacial spasm caused by an aberrant jugular branch of the ascending pharyngeal artery.
Br J Neurosurg
PUBLISHED: 09-19-2014
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We present the first report of a case of hemifacial spasm caused by an anomalous, enlarged branch of the ascending pharyngeal artery and treated with microvascular decompression. Clinicians must appreciate unusual causes of hemifacial spasm so that patients are not denied a curative operation due to atypical radiographic findings.
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Enhancing the Buccal Mucosal Delivery of Peptide and Protein Therapeutics.
Pharm. Res.
PUBLISHED: 08-29-2014
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With continuing advances in biotechnology and genetic engineering, there has been a dramatic increase in the availability of new biomacromolecules, such as peptides and proteins that have the potential to ameliorate the symptoms of many poorly-treated diseases. Although most of these macromolecular therapeutics exhibit high potency, their large molecular mass, susceptibility to enzymatic degradation, immunogenicity and tendency to undergo aggregation, adsorption, and denaturation have limited their ability to be administered via the traditional oral route. As a result, alternative noninvasive routes have been investigated for the systemic delivery of these macromolecules, one of which is the buccal mucosa. The buccal mucosa offers a number of advantages over the oral route, making it attractive for the delivery of peptides and proteins. However, the buccal mucosa still exhibits some permeability-limiting properties, and therefore various methods have been explored to enhance the delivery of macromolecules via this route, including the use of chemical penetration enhancers, physical methods, particulate systems and mucoadhesive formulations. The incorporation of anti-aggregating agents in buccal formulations also appears to show promise in other mucosal delivery systems, but has not yet been considered for buccal mucosal drug delivery. This review provides an update on recent approaches that have shown promise in enhancing the buccal mucosal transport of macromolecules, with a major focus on proteins and peptides.
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A potent cyclic peptide targeting SPSB2 protein as a potential anti-infective agent.
J. Med. Chem.
PUBLISHED: 08-06-2014
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The protein SPSB2 mediates proteosomal degradation of inducible nitric oxide synthase (iNOS). Inhibitors of SPSB2-iNOS interaction may prolong the lifetime of iNOS and thereby enhance the killing of persistent pathogens. We have designed a cyclic peptide, Ac-c[CVDINNNC]-NH2, containing the key sequence motif mediating the SPSB2-iNOS interaction, which binds to the iNOS binding site on SPSB2 with a Kd of 4.4 nM, as shown by SPR, [(1)H,(15)N]-HSQC, and (19)F NMR. An in vitro assay on macrophage cell lysates showed complete inhibition of SPSB2-iNOS interactions by the cyclic peptide. Furthermore, its solution structure closely matched (backbone rmsd 1.21 Å) that of the SPSB2-bound linear DINNN peptide. The designed peptide was resistant to degradation by the proteases pepsin, trypsin, and chymotrypsin and stable in human plasma. This cyclic peptide exemplifies potentially a new class of anti-infective agents that acts on the host innate response, thereby avoiding the development of pathogen resistance.
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Ligand-induced conformational change of Plasmodium falciparum AMA1 detected using 19F NMR.
J. Med. Chem.
PUBLISHED: 08-05-2014
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We established an efficient means of probing ligand-induced conformational change in the malaria drug target AMA1 using 19F NMR. AMA1 was labeled with 5-fluorotryptophan (5F-Trp), and the resulting 5F-Trp resonances were assigned by mutagenesis of the native Trp residues. By introducing additional Trp residues at strategic sites within a ligand-responsive loop, we detected distinct conformational consequences when various peptide and small-molecule ligands bound AMA1. Our results demonstrate an increase in flexibility in this loop caused by the native ligand, as inferred from, but not directly observed in, crystal structures. In addition, we found evidence for long-range allosteric changes in AMA1 that are not observed crystallographically. This method will be valuable in ongoing efforts to identify and characterize therapeutically relevant inhibitors of protein-protein interactions involving AMA1 and is generalizable to the study of ligand-induced conformational change in a wide range of other drug targets.
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Flagellar synchronization through direct hydrodynamic interactions.
Elife
PUBLISHED: 07-31-2014
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Flows generated by ensembles of flagella are crucial to development, motility and sensing, but the mechanisms behind this striking coordination remain unclear. We present novel experiments in which two micropipette-held somatic cells of Volvox carteri, with distinct intrinsic beating frequencies, are studied by high-speed imaging as a function of their separation and orientation. Analysis of time series shows that the interflagellar coupling, constrained by lack of connections between cells to be hydrodynamical, exhibits a spatial dependence consistent with theory. At close spacings it produces robust synchrony for thousands of beats, while at increasing separations synchrony is degraded by stochastic processes. Manipulation of the relative flagellar orientation reveals in-phase and antiphase states, consistent with dynamical theories. Flagellar tracking with exquisite precision reveals waveform changes that result from hydrodynamic coupling. This study proves unequivocally that flagella coupled solely through a fluid can achieve robust synchrony despite differences in their intrinsic properties.DOI: http://dx.doi.org/10.7554/eLife.02750.001.
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Hemifacial Spasm and Neurovascular Compression.
ScientificWorldJournal
PUBLISHED: 07-04-2014
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Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck. Its prevalence is 9.8 per 100,000 persons with an average age of onset of 44 years. The accepted pathophysiology of HFS suggests that it is a disease process of the nerve root entry zone of the facial nerve. HFS can be divided into two types: primary and secondary. Primary HFS is triggered by vascular compression whereas secondary HFS comprises all other causes of facial nerve damage. Clinical examination and imaging modalities such as electromyography (EMG) and magnetic resonance imaging (MRI) are useful to differentiate HFS from other facial movement disorders and for intraoperative planning. The standard medical management for HFS is botulinum neurotoxin (BoNT) injections, which provides low-risk but limited symptomatic relief. The only curative treatment for HFS is microvascular decompression (MVD), a surgical intervention that provides lasting symptomatic relief by reducing compression of the facial nerve root. With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve.
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?-Agonist-mediated relaxation of airway smooth muscle is protein kinase A-dependent.
J. Biol. Chem.
PUBLISHED: 06-27-2014
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Inhaled ?-agonists are effective at reversing bronchoconstriction in asthma, but the mechanism by which they exert this effect is unclear and controversial. PKA is the historically accepted effector, although this assumption is made on the basis of associative and not direct evidence. Recent studies have asserted that exchange protein activated by cAMP (Epac), not PKA, mediates the relaxation of airway smooth muscle (ASM) observed with ?-agonist treatment. This study aims to clarify the role of PKA in the prorelaxant effects of ?-agonists on ASM. Inhibition of PKA activity via expression of the PKI and RevAB peptides results in increased ?-agonist-mediated cAMP release, abolishes the inhibitory effect of isoproterenol on histamine-induced intracellular calcium flux, and significantly attenuates histamine-stimulated MLC-20 phosphorylation. Analyses of ASM cell and tissue contraction demonstrate that PKA inhibition eliminates most, if not all, ?-agonist-mediated relaxation of contracted smooth muscle. Conversely, Epac knockdown had no effect on the regulation of contraction or procontractile signaling by isoproterenol. These findings suggest that PKA, not Epac, is the predominant and physiologically relevant effector through which ?-agonists exert their relaxant effects.
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Fluid flows created by swimming bacteria drive self-organization in confined suspensions.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 06-23-2014
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Concentrated suspensions of swimming microorganisms and other forms of active matter are known to display complex, self-organized spatiotemporal patterns on scales that are large compared with those of the individual motile units. Despite intensive experimental and theoretical study, it has remained unclear the extent to which the hydrodynamic flows generated by swimming cells, rather than purely steric interactions between them, drive the self-organization. Here we use the recent discovery of a spiral-vortex state in confined suspensions of Bacillus subtilis to study this issue in detail. Those experiments showed that if the radius of confinement in a thin cylindrical chamber is below a critical value, the suspension will spontaneously form a steady single-vortex state encircled by a counter-rotating cell boundary layer, with spiral cell orientation within the vortex. Left unclear, however, was the flagellar orientation, and hence the cell swimming direction, within the spiral vortex. Here, using a fast simulation method that captures oriented cell-cell and cell-fluid interactions in a minimal model of discrete particle systems, we predict the striking, counterintuitive result that in the presence of collectively generated fluid motion, the cells within the spiral vortex actually swim upstream against those flows. This prediction is then confirmed by the experiments reported here, which include measurements of flagella bundle orientation and cell tracking in the self-organized state. These results highlight the complex interplay between cell orientation and hydrodynamic flows in concentrated suspensions of microorganisms.
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Conformational Flexibility in the Binding Surface of the Potassium Channel Blocker ShK.
Chembiochem
PUBLISHED: 06-08-2014
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ShK is a 35-residue peptide that binds with high affinity to human voltage-gated potassium channels through a conserved K-Y dyad. Here we have employed NMR measurements of backbone-amide (15) N spin-relaxation rates to investigate motions of the ShK backbone. Although ShK is rigid on the ps to ns timescale, increased linewidths observed for 11 backbone-amide (15) N resonances identify chemical or conformational exchange contributions to the spin relaxation. Relaxation dispersion profiles indicate that exchange between major and minor conformers occurs on the sub-millisecond timescale. Affected residues are mostly clustered around the central helix-kink-helix structure and the critical K22-Y23 motif. We suggest that the less structured minor conformer increases the exposure of Y23, known to contribute to binding affinity and selectivity, thereby facilitating its interaction with potassium channels. These findings have potential implications for the design of new channel blockers based on ShK.
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Kv1.3 channel-blocking immunomodulatory peptides from parasitic worms: implications for autoimmune diseases.
FASEB J.
PUBLISHED: 06-04-2014
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The voltage-gated potassium (Kv) 1.3 channel is widely regarded as a therapeutic target for immunomodulation in autoimmune diseases. ShK-186, a selective inhibitor of Kv1.3 channels, ameliorates autoimmune diseases in rodent models, and human phase 1 trials of this agent in healthy volunteers have been completed. In this study, we identified and characterized a large family of Stichodactyla helianthus toxin (ShK)-related peptides in parasitic worms. Based on phylogenetic analysis, 2 worm peptides were selected for study: AcK1, a 51-residue peptide expressed in the anterior secretory glands of the dog-infecting hookworm Ancylostoma caninum and the human-infecting hookworm Ancylostoma ceylanicum, and BmK1, the C-terminal domain of a metalloprotease from the filarial worm Brugia malayi. These peptides in solution adopt helical structures closely resembling that of ShK. At doses in the nanomolar-micromolar range, they block native Kv1.3 in human T cells and cloned Kv1.3 stably expressed in L929 mouse fibroblasts. They preferentially suppress the proliferation of rat CCR7(-) effector memory T cells without affecting naive and central memory subsets and inhibit the delayed-type hypersensitivity (DTH) response caused by skin-homing effector memory T cells in rats. Further, they suppress IFN? production by human T lymphocytes. ShK-related peptides in parasitic worms may contribute to the potential beneficial effects of probiotic parasitic worm therapy in human autoimmune diseases.-Chhabra, S., Chang, S. C., Nguyen, H. M., Huq, R., Tanner, M. R., Londono, L. M., Estrada, R., Dhawan, V., Chauhan, S., Upadhyay, S. K., Gindin, M., Hotez, P. J., Valenzuela, J. G., Mohanty, B., Swarbrick, J. D., Wulff, H., Iadonato, S. P., Gutman, G. A., Beeton, C., Pennington, M. W., Norton, R. S., Chandy, K. G. Kv1.3 channel-blocking immunomodulatory peptides from parasitic worms: implications for autoimmune diseases.
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Rheotaxis facilitates upstream navigation of mammalian sperm cells.
Elife
PUBLISHED: 05-29-2014
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A major puzzle in biology is how mammalian sperm maintain the correct swimming direction during various phases of the sexual reproduction process. Whilst chemotaxis may dominate near the ovum, it is unclear which cues guide spermatozoa on their long journey towards the egg. Hypothesized mechanisms range from peristaltic pumping to temperature sensing and response to fluid flow variations (rheotaxis), but little is known quantitatively about them. We report the first quantitative study of mammalian sperm rheotaxis, using microfluidic devices to investigate systematically swimming of human and bull sperm over a range of physiologically relevant shear rates and viscosities. Our measurements show that the interplay of fluid shear, steric surface-interactions, and chirality of the flagellar beat leads to stable upstream spiralling motion of sperm cells, thus providing a generic and robust rectification mechanism to support mammalian fertilisation. A minimal mathematical model is presented that accounts quantitatively for the experimental observations.DOI: http://dx.doi.org/10.7554/eLife.02403.001.
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Factors Related to Psychotropic Drug Prescription for Neuropsychiatric Symptoms in Nursing Home Residents With Dementia.
J Am Med Dir Assoc
PUBLISHED: 05-27-2014
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The objective of this study is to explore factors that elucidate reasons for psychotropic drug (PD) prescription for neuropsychiatric symptoms (NPS) in nursing home (NH) residents with dementia.
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Development of a practice guideline for optimal symptom relief for patients with pneumonia and dementia in nursing homes using a Delphi study.
Int J Geriatr Psychiatry
PUBLISHED: 05-24-2014
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This study aimed to develop a practice guideline for a structured and consensus-based approach to relieve symptoms of pneumonia in patients with dementia in nursing homes.
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Boundary singularities produced by the motion of soap films.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 05-19-2014
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Recent work has shown that a Möbius strip soap film rendered unstable by deforming its frame changes topology to that of a disk through a "neck-pinching" boundary singularity. This behavior is unlike that of the catenoid, which transitions to two disks through a bulk singularity. It is not yet understood whether the type of singularity is generally a consequence of the surface topology, nor how this dependence could arise from an equation of motion for the surface. To address these questions we investigate experimentally, computationally, and theoretically the route to singularities of soap films with different topologies, including a family of punctured Klein bottles. We show that the location of singularities (bulk or boundary) may depend on the path of the boundary deformation. In the unstable regime the driving force for soap-film motion is the mean curvature. Thus, the narrowest part of the neck, associated with the shortest nontrivial closed geodesic of the surface, has the highest curvature and is the fastest moving. Just before onset of the instability there exists on the stable surface the shortest closed geodesic, which is the initial condition for evolution of the neck's geodesics, all of which have the same topological relationship to the frame. We make the plausible conjectures that if the initial geodesic is linked to the boundary, then the singularity will occur at the boundary, whereas if the two are unlinked initially, then the singularity will occur in the bulk. Numerical study of mean curvature flows and experiments support these conjectures.
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Decision making about change of medication for comorbid disease at the end of life: an integrative review.
Drugs Aging
PUBLISHED: 05-15-2014
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The main goal of palliative care is to improve quality of life by treating symptoms in patients with life-threatening illnesses. Most patients suffer from more than five severe comorbidities in the last 6 months of life. However, for patients receiving palliative care, interventions to prevent possible long-term complications of these comorbidities are no longer the primary aim of care. This paper aimed to review the literature regarding decision making about medication for comorbid disease at the end of life, defined as a life expectancy <3 months, and to formulate preliminary recommendations based on the existing literature. An integrative review approach was used. We searched the MEDLINE, EMBASE, and CINAHL databases. Papers were included if they had been published in the English language between 1 January 1995 and 31 December 2013, with an abstract. Additional studies were identified by searching bibliographies. Factors to consider when systematically reviewing medications are the goals of care, remaining life expectancy, treatment targets, time until benefit, number needed to treat, number needed to harm, and adverse drug reactions. Existing research focuses particularly on the use of certain drug classes during end-of-life care, including statins, antihypertensive agents, anticoagulants, antihyperglycaemic agents and antibiotics. Based on the results of this review, we made preliminary recommendations for these medication groups. Medication that does not benefit the patient in any way should be avoided. The aim of medication at the end of life should be symptom control. There is a need for prospective trials to give further insight into the decision-making process of medication management at the end of life.
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GPCRs and arrestins in airways: implications for asthma.
Handb Exp Pharmacol
PUBLISHED: 04-20-2014
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The obstructive lung disease asthma is treated by drugs that target, either directly or indirectly, G protein-coupled receptors (GPCRs). GPCRs coupled to Gq are the primary mediators of airway smooth muscle (ASM) contraction and increased airway resistance, whereas the Gs-coupled beta-2-adrenoceptor (?2AR) promotes pro-relaxant signaling in and relaxation of ASM resulting in greater airway patency and reversal of life-threatening bronchoconstriction. In addition, GPCR-mediated functions in other cell types, including airway epithelium and hematopoietic cells, are involved in the control of lung inflammation that causes most asthma. The capacity of arrestins to regulate GPCR signaling, via either control of GPCR desensitization/resensitization or G protein-independent signaling, renders arrestins an intriguing therapeutic target for asthma and other obstructive lung diseases. This review will focus on the potential role of arrestins in those GPCR-mediated airway cell functions that are dysregulated in asthma.
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Determinants of geriatric patients' quality of life after stroke rehabilitation.
Aging Ment Health
PUBLISHED: 03-31-2014
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Geriatric patients' physical disabilities, dependency on care, and possible psychological ill-being may negatively affect both the patient's quality of life and the informal caregiver burden. Focusing on this interrelationship which can be particularly prominent in geriatric patients with stroke, the objective of this study was to identify determinants of patients' quality of life and informal caregiver burden.
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(19) F NMR as a Probe of Ligand Interactions with the iNOS Binding site of SPRY Domain-Containing SOCS Box Protein 2.
Chem Biol Drug Des
PUBLISHED: 03-12-2014
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SPRY domain-containing SOCS box protein 2 (SPSB2) regulates inducible nitric oxide synthase (iNOS) by targeting it for proteasomal degradation. Inhibiting this interaction prolongs the intracellular lifetime of iNOS, leading in turn to enhanced killing of infectious pathogens such as bacteria and parasites. SPSB2 recognizes a linear motif (DINNN) in the disordered N-terminus of iNOS, and ligands that target the DINNN binding site on SPSB2 are potentially novel anti-infective agents. We have explored (19) F NMR as a means of probing ligand binding to SPSB2. All six Trp residues in SPSB2 were replaced with 5-fluorotryptophan (5-F-Trp) by utilizing a Trp auxotroph strain of Escherichia coli. The labeled protein was well folded and bound a DINNN-containing peptide with similar affinity to native SPSB2. Six well-resolved 5-F-Trp resonances were observed in the (19) F NMR spectrum and were assigned using site-directed mutagenesis. The (19) F resonance of W207 was significantly perturbed upon binding to DINNN-containing peptides. Other resonances were perturbed to a lesser extent although in a way that was sensitive to the composition of the peptide. Analogues of compounds identified in a fragment screen also perturbed the W207 resonance, confirming their binding to the iNOS peptide-binding site on SPSB2. (19) F NMR promises to be a valuable approach in developing inhibitors that bind to the DINNN binding site.
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A potent and Kv1.3-selective analogue of the scorpion toxin HsTX1 as a potential therapeutic for autoimmune diseases.
Sci Rep
PUBLISHED: 03-12-2014
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HsTX1 toxin, from the scorpion Heterometrus spinnifer, is a 34-residue, C-terminally amidated peptide cross-linked by four disulfide bridges. Here we describe new HsTX1 analogues with an Ala, Phe, Val or Abu substitution at position 14. Complexes of HsTX1 with the voltage-gated potassium channels Kv1.3 and Kv1.1 were created using docking and molecular dynamics simulations, then umbrella sampling simulations were performed to construct the potential of mean force (PMF) of the ligand and calculate the corresponding binding free energy for the most stable configuration. The PMF method predicted that the R14A mutation in HsTX1 would yield a > 2?kcal/mol gain for the Kv1.3/Kv1.1 selectivity free energy relative to the wild-type peptide. Functional assays confirmed the predicted selectivity gain for HsTX1[R14A] and HsTX1[R14Abu], with an affinity for Kv1.3 in the low picomolar range and a selectivity of more than 2,000-fold for Kv1.3 over Kv1.1. This remarkable potency and selectivity for Kv1.3, which is significantly up-regulated in activated effector memory cells in humans, suggest that these analogues represent valuable leads in the development of therapeutics for autoimmune diseases.
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Neuropsychiatric symptoms in patients with dementia in primary care: a study protocol.
BMC Geriatr
PUBLISHED: 03-11-2014
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Neuropsychiatric symptoms (NPS) frequently occur in patients with dementia. To date, prospective studies on the course of NPS have been conducted in patients with dementia in clinical centers or psychiatric services. The primary goal of this study is to investigate the course of NPS in patients with dementia and caregiver distress in primary care. We also aim to detect determinants of both the course of NPS in patients with dementia and informal caregiver distress in primary care.
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Interactions of disulfide-deficient selenocysteine analogs of ?-conotoxin BuIIIB with the ?-subunit of the voltage-gated sodium channel subtype 1.3.
FEBS J.
PUBLISHED: 03-10-2014
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Inhibitors of the ?-subunit of the voltage-gated sodium channel subtype 1.3 (NaV 1.3) are of interest as pharmacological tools for the study of neuropathic pain associated with spinal cord injury and have potential therapeutic applications. The recently described ?-conotoxin BuIIIB (?-BuIIIB) from Conus bullatus was shown to block NaV 1.3 with submicromolar potency (Kd = 0.2 ?m), making it one of the most potent peptidic inhibitors of this subtype described to date. However, oxidative folding of ?-BuIIIB results in numerous folding isoforms, making it difficult to obtain sufficient quantities of the active form of the peptide for detailed structure-activity studies. In the present study, we report the synthesis and characterization of ?-BuIIIB analogs incorporating a disulfide-deficient, diselenide-containing scaffold designed to simplify synthesis and facilitate structure-activity studies directed at identifying amino acid residues involved in NaV 1.3 blockade. Our results indicate that, similar to other ?-conotoxins, the C-terminal residues (Trp16, Arg18 and His20) are most crucial for NaV 1 blockade. At the N-terminus, replacement of Glu3 by Ala resulted in an analog with an increased potency for NaV 1.3 (Kd = 0.07 ?m), implicating this position as a potential site for modification for increased potency and/or selectivity. Further examination of this position showed that increased negative charge, through ?-carboxyglutamate replacement, decreased potency (Kd = 0.33 ?m), whereas replacement with positively-charged 2,4-diamonobutyric acid increased potency (Kd = 0.036 ?m). These results provide a foundation for the design and synthesis of ?-BuIIIB-based analogs with increased potency against NaV 1.3.
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Thin-slice T2 MRI imaging predicts vascular pathology in hemifacial spasm: a case-control study.
Mov. Disord.
PUBLISHED: 01-15-2014
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Hemifacial spasm (HFS) is a condition that may severely reduce patients' quality of life. We sought to determine the sensitivity and specificity of thin-slice T2 magnetic resonance imaging (MRI) for detecting vascular compression in HFS patients. Prospective information was collected on 28 patients with HFS who presented to our center between March 2011 and March 2012 with thin-slice T2 MR imaging. The sensitivity and specificity for differentiating patients from controls were calculated. Sensitivities were 78.6% and 92.9% for the blinded radiologists and 75% for the partially blinded neurosurgeon. Specificities were 42.9% and 28.6% for the blinded radiologists and 75% for the partially blinded neurosurgeon. Magnetic resonance imaging of the facial nerve can guide clinicians in selecting patients who are good surgical candidates. Thin-slice T2 MRI should be viewed as supportive rather than diagnostic.
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Crosstalk between beta-2-adrenoceptor and muscarinic acetylcholine receptors in the airway.
Curr Opin Pharmacol
PUBLISHED: 01-15-2014
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The M3 and M2 muscarinic acetylcholine receptors (mAChRs) and beta-2-adrenoceptors (?2ARs) are important regulators of airway cell function, and drugs targeting these receptors are among the first line drugs in the treatment of the obstructive lung diseases asthma and chronic obstructive lung disease (COPD). Cross-regulation or crosstalk between mAChRs and ?2ARs in airway smooth muscle (ASM) helps determine the contractile state of the muscle, thus airway diameter and resistance to airflow. In this review we will detail mAChR and ?2AR-signaling and crosstalk, focusing on events in the ASM cell but also addressing the function of these receptors in other cell types that impact airway physiology. We conclude by discussing how recent advances in GPCR pharmacology offer a unique opportunity to fine tune mAChR and ?2AR signaling and their crosstalk, and thereby produce superior therapeutics for obstructive lung and other diseases.
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Prevalence and correlates of psychotropic drug use in community-dwelling people with young-onset dementia: the NeedYD-study.
Int Psychogeriatr
PUBLISHED: 01-10-2014
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ABSTRACT Background: Young-onset dementia (YOD) is defined as dementia that develops before the age of 65 years. The prevalence and type of neuropsychiatric symptoms (NPS) in YOD differ from patients with late onset dementia. NPS in dementia patients are often treated with psychotropic drugs. The aim of this study was to investigate psychotropic drug use (PDU) in Dutch community-dwelling YOD patients and the association between age, gender, dementia etiology and severity, symptoms of depression, disease awareness, unmet needs, and type of NPS.
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RASP: rapid and robust backbone chemical shift assignments from protein structure.
J. Biomol. NMR
PUBLISHED: 01-09-2014
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Chemical shift prediction has an unappreciated power to guide backbone resonance assignment in cases where protein structure is known. Here we describe Resonance Assignment by chemical Shift Prediction (RASP), a method that exploits this power to derive protein backbone resonance assignments from chemical shift predictions. Robust assignments can be obtained from a minimal set of only the most sensitive triple-resonance experiments, even for spectroscopically challenging proteins. Over a test set of 154 proteins RASP assigns 88 % of residues with an accuracy of 99.7 %, using only information available from HNCO and HNCA spectra. Applied to experimental data from a challenging 34 kDa protein, RASP assigns 90 % of manually assigned residues using only 40 % of the experimental data required for the manual assignment. RASP has the potential to significantly accelerate the backbone assignment process for a wide range of proteins for which structural information is available, including those for which conventional assignment strategies are not feasible.
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Primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma?with KIR3DL2 and NKp46 expression in a human immunodeficiency virus carrier.
J. Cutan. Pathol.
PUBLISHED: 01-06-2014
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Primary cutaneous aggressive epidermotropic T-cell lymphoma (PCAETCL) is a very rare lymphoma characterized by rapidly growing necrotic cutaneous lesions with an epidermotropic CD8(+) T-cell neoplastic infiltrate observed histopathologically. It is associated with a very poor outcome, despite aggressive multi-agent chemotherapy. We report a 49-year-old human immunodeficiency virus (HIV)-infected patient who developed PCAETCL with associated marked vascular injury leading to diffuse purpuric and necrotic lesions complicated by recalcitrant hemophagocytic activation syndrome. The lymphoma strongly and diffusely expressed CD158k/KIR3DL2 at the protein and transcript level and NKp46 transcripts, in addition to CD8 and cytotoxic proteins. We observed a diffuse CD158k/KIR3DL2 protein expression in another case of PAETCL, not associated with immunodeficiency, which was used as a positive control. PCAETCL can develop in HIV-infected patients and may present in vasculitis-like fashion. The possible role of immunsuppression and/or HIV in oncogenesis can be postulated, as patients with HIV may develop anti-HIV cytotoxic CD8(+) lymphoproliferations. The frequency of CD158k/KIR3DL2 and NKp46 expression in PCAECL remains to be studied in a series of cases, and may represent interesting targets for future treatments.
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Molecular Insights into the Interaction between Plasmodium falciparum Apical Membrane Antigen 1 and an Invasion-Inhibitory Peptide.
PLoS ONE
PUBLISHED: 01-01-2014
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Apical membrane antigen 1 (AMA1) of the human malaria parasite Plasmodium falciparum has been implicated in invasion of the host erythrocyte. It interacts with malarial rhoptry neck (RON) proteins in the moving junction that forms between the host cell and the invading parasite. Agents that block this interaction inhibit invasion and may serve as promising leads for anti-malarial drug development. The invasion-inhibitory peptide R1 binds to a hydrophobic cleft on AMA1, which is an attractive target site for small molecules that block parasite invasion. In this work, truncation and mutational analyses show that Phe5-Phe9, Phe12 and Arg15 in R1 are the most important residues for high affinity binding to AMA1. These residues interact with two well-defined binding hot spots on AMA1. Computational solvent mapping reveals that one of these hot spots is suitable for small molecule targeting. We also confirm that R1 in solution binds to AMA1 with 1?1 stoichiometry and adopts a secondary structure consistent with the major form of R1 observed in the crystal structure of the complex. Our results provide a basis for designing high affinity inhibitors of the AMA1-RON2 interaction.
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Lag, lock, sync, slip: the many 'phases' of coupled flagella.
J R Soc Interface
PUBLISHED: 01-01-2014
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In a multitude of life's processes, cilia and flagella are found indispensable. Recently, the biflagellated chlorophyte alga Chlamydomonas has become a model organism for the study of ciliary motility and synchronization. Here, we use high-speed, high-resolution imaging of single pipette-held cells to quantify the rich dynamics exhibited by their flagella. Underlying this variability in behaviour are biological dissimilarities between the two flagella-termed cis and trans, with respect to a unique eyespot. With emphasis on the wild-type, we derive limit cycles and phase parametrizations for self-sustained flagellar oscillations from digitally tracked flagellar waveforms. Characterizing interflagellar phase synchrony via a simple model of coupled oscillators with noise, we find that during the canonical swimming breaststroke the cis flagellum is consistently phase-lagged relative to, while remaining robustly phase-locked with, the trans flagellum. Transient loss of synchrony, or phase slippage, may be triggered stochastically, in which the trans flagellum transitions to a second mode of beating with attenuated beat envelope and increased frequency. Further, exploiting this alga's ability for flagellar regeneration, we mechanically induced removal of one or the other flagellum of the same cell to reveal a striking disparity between the beatings of the cis and trans flagella, in isolation. These results are evaluated in the context of the dynamic coordination of Chlamydomonas flagella.
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Diversity of conotoxin gene superfamilies in the venomous snail, Conus victoriae.
PLoS ONE
PUBLISHED: 01-01-2014
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Animal venoms represent a vast library of bioactive peptides and proteins with proven potential, not only as research tools but also as drug leads and therapeutics. This is illustrated clearly by marine cone snails (genus Conus), whose venoms consist of mixtures of hundreds of peptides (conotoxins) with a diverse array of molecular targets, including voltage- and ligand-gated ion channels, G-protein coupled receptors and neurotransmitter transporters. Several conotoxins have found applications as research tools, with some being used or developed as therapeutics. The primary objective of this study was the large-scale discovery of conotoxin sequences from the venom gland of an Australian cone snail species, Conus victoriae. Using cDNA library normalization, high-throughput 454 sequencing, de novo transcriptome assembly and annotation with BLASTX and profile hidden Markov models, we discovered over 100 unique conotoxin sequences from 20 gene superfamilies, the highest diversity of conotoxins so far reported in a single study. Many of the sequences identified are new members of known conotoxin superfamilies, some help to redefine these superfamilies and others represent altogether new classes of conotoxins. In addition, we have demonstrated an efficient combination of methods to mine an animal venom gland and generate a library of sequences encoding bioactive peptides.
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The economics of dementia-care mapping in nursing homes: a cluster-randomised controlled trial.
PLoS ONE
PUBLISHED: 01-01-2014
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Dementia-care mapping (DCM) is a cyclic intervention aiming at reducing neuropsychiatric symptoms in people with dementia in nursing homes. Alongside an 18-month cluster-randomized controlled trial in which we studied the effectiveness of DCM on residents and staff outcomes, we investigated differences in costs of care between DCM and usual care in nursing homes.
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The experiences and needs of children living with a parent with young onset dementia: results from the NeedYD study.
Int Psychogeriatr
PUBLISHED: 11-14-2013
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ABSTRACT Background: Children of patients with young onset dementia (YOD) who are confronted with a parent who has a progressive disease, often assist in caregiving tasks, which may have a great impact on their lives. The objective of the present study is to explore the experiences of children living with a young parent with dementia with a specific focus on the childrens needs. Methods: Semi-structured interviews with 14 adolescent children between the ages of 15 and 27 years of patients with YOD were analyzed using inductive content analysis. Themes were identified based on the established codes. Results: The emerging categories were divided into three themes that demonstrated the impact of dementia on daily life, different ways of coping with the disease, and childrens need for care and support. The children had difficulties managing all of the responsibilities and showed concerns about their future. To deal with these problems, they demonstrated various coping styles, such as avoidant or adaptive coping. Although most children were initially reluctant to seek professional care, several of them expressed the need for practical guidance to address the changing behavior of their parent. The children felt more comfortable talking to someone who was familiar with their situation and who had specific knowledge of YOD and the available services. Conclusion: In addition to practical information, more accessible and specific information about the diagnosis and the course of YOD is needed to provide a better understanding of the disease for the children. These findings underline the need for a personal, family-centered approach.
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Determinants of the administration of continuous palliative sedation: a systematic review.
J Palliat Med
PUBLISHED: 11-14-2013
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Abstract Background: Little is known about the determining factors related to the administration of continuous palliative sedation. Knowledge of these determinants may assist physicians in identifying patients who are at high risk of developing refractory symptoms, enable physicians to inform patients, and optimize close monitoring. Objective: The aim of this systematic review was to identify determinants of the administration of continuous palliative sedation. Design: A systematic review of PubMed, EMBASE, and CINAHL was performed to identify English, Dutch, and German language papers published from January 1990 through April 2011. Inclusion was based on the following criteria: patient-based research on continuous palliative sedation, studies investigating determinants of palliative sedation and/or comparison between sedated and nonsedated cohorts, and studies using multivariate analyses and of fair to good or good methodological quality. Results: In total, eight papers were reviewed. The following nine factors were found to be associated with the administration of continuous palliative sedation: younger age, male sex, having cancer, feelings of hopelessness, dying in a hospital, living in a Dutch speaking community setting, very nonreligious or extremely nonreligious physicians, physicians working in "other hospital" specialties, and physicians in favor of assisted death. Conclusions: Given the variation in study designs and the limitations of the included studies, the outcomes should be interpreted carefully. Further research is needed, particularly regarding factors that can be influenced and that may alter the course of a patients symptoms and the patients eventual need for palliative sedation.
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Concurrent Incidence of Adverse Events in Hospitals and Nursing Homes.
J Nurs Scholarsh
PUBLISHED: 11-13-2013
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To describe the concurrent incidence of pressure ulcers, urinary tract infections, and falls in hospitals and nursing homes, and the preventive care given. Additionally, the correlation between the occurrence of these adverse events and preventive care was explored.
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Structure and function of the SPRY/B30.2 domain proteins involved in innate immunity.
Protein Sci.
PUBLISHED: 11-05-2013
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The SPRY domain is a protein interaction module found in 77 murine and ~100 human proteins, and is implicated in important biological pathways, including those that regulate innate and adaptive immunity. The current definition of the SPRY domain is based on a sequence repeat discovered in the splA kinase and ryanodine receptors. The greater SPRY family is divided into the B30.2 (which contains a PRY extension at the N-terminus) and "SPRY-only" sub-families. In this brief review, we examine the current structural and biochemical literature on SPRY/B30.2 domain involvement in key immune processes and highlight a PRY-like 60 amino acid region in the N-terminus of "SPRY-only" proteins. Phylogenetic, structural, and functional analyses suggest that this N-terminal region is related to the PRY region of B30.2 and should be characterized as part of an extended SPRY domain. Greater understanding of the functional importance of the N-terminal region in "SPRY only" proteins will enhance our ability to interrogate SPRY interactions with their respective binding partners.
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PROPER I: frequency and appropriateness of psychotropic drugs use in nursing home patients and its associations: a study protocol.
BMC Psychiatry
PUBLISHED: 10-18-2013
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Nursing home patients with dementia use psychotropic drugs longer and more frequently than recommended by guidelines implying psychotropic drugs are not always prescribed appropriately. These drugs can have many side effects and effectiveness is limited. Psychotropic drug use between nursing home units varies and is not solely related to the severity of neuropsychiatric symptoms. There is growing evidence indicating that psychotropic drug use is associated with environmental factors, suggesting that the prescription of psychotropic drugs is not only related to (objective) patient factors. However, other factors related to the patient, elderly care physician, nurse and the physical environment are only partially identified. Using a mixed method of qualitative and quantitative research, this study aims to understand the nature of psychotropic drug use and its underlying factors by identifying: 1) frequency and appropriateness of psychotropic drug use for neuropsychiatric symptoms in nursing home patients with dementia, 2) factors associated with (appropriateness of) psychotropic drug use.
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Improving psychotropic drug prescription in nursing home patients with dementia: design of a cluster randomized controlled trial.
BMC Psychiatry
PUBLISHED: 10-17-2013
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Neuropsychiatric symptoms are highly prevalent in nursing home patients with dementia. Despite modest effectiveness and considerable side effects, psychotropic drugs are frequently prescribed for these neuropsychiatric symptoms. This raises questions whether psychotropic drugs are appropriately prescribed. The aim of the PROPER (PRescription Optimization of Psychotropic drugs in Elderly nuRsing home patients with dementia) II study is to investigate the efficacy of an intervention for improving the appropriateness of psychotropic drug prescription in nursing home patients with dementia.Methods/design: The PROPER II study is a multi-center cluster randomized controlled, pragmatic trial using parallel groups. It has a duration of eighteen months and four six-monthly assessments. Six nursing homes will participate in the intervention and six will continue care as usual. The nursing homes will be located throughout the Netherlands, each participating with two dementia special care units with an average of fifteen patients per unit, resulting in 360 patients. The intervention consists of a structured and repeated multidisciplinary medication review supported by education and continuous evaluation. It is conducted by pharmacists, physicians, and nurses and consists of three components: 1) preparation and education, 2) conduct, and 3) evaluation/guidance. The primary outcome is the proportion of patients with appropriate psychotropic drug use. Secondary outcomes are the overall frequency of psychotropic drug use, neuropsychiatric symptoms, quality of life, activities of daily living, psychotropic drug side effects and adverse events (including cognition, comorbidity, and mortality). Besides, a process analysis on the intervention will be carried out.
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Exploiting functional domains of GRK2/3 to alter the competitive balance of pro- and anticontractile signaling in airway smooth muscle.
FASEB J.
PUBLISHED: 10-16-2013
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To clarify the potential utility of targeting GRK2/3-mediated desensitization as a means of manipulating airway smooth muscle (ASM) contractile state, we assessed the specificity of GRK2/3 regulation of procontractile and relaxant G-protein-coupled receptors in ASM. Functional domains of GRK2/3 were stably expressed, or siRNA-mediated GRK2/3 knockdown was performed, in human ASM cultures, and agonist-induced signaling was assessed. Regulation of contraction of murine tracheal rings expressing GRK2 C terminus was also assessed. GRK2/3 knockdown or expression of the GRK2 C terminus caused a significant (?30-90%) increase in maximal ?-agonist and histamine [phosphoinositide (PI) hydrolysis] signaling, without affecting the calculated EC50. GRK2 C-terminal expression did not affect signaling by methacholine, thrombin, or LTD4. Expression of the GRK2 N terminus or kinase-dead holo-GRK2 diminished (?30-70%) both PI hydrolysis and Ca(2+) mobilization by every Gq-coupled receptor examined. Under conditions of GRK2 C-terminal expression, ?-agonist inhibition of methacholine-stimulated PI hydrolysis was greater. Finally, transgenic expression of the GRK2 C terminus in murine ASM enabled ?30-50% greater ?-agonist-mediated relaxation of methacholine-induced contraction. Collectively these data demonstrate the relative selectivity of GRKs for the ?2AR in ASM and the ability to exploit GRK2/3 functional domains to render ASM hyporesponsive to contractile agents while increasing responsiveness to bronchodilating ?-agonist.-Deshpande, D. A., Yan, H., Kong, K.-C., Tiegs, B. C., Morgan, S. J., Pera, T., Panettieri, R. A., Eckhart, A. D., Penn, R. B. Exploiting functional domains of GRK2/3 to alter the competitive balance of pro- and anticontractile signaling in airway smooth muscle.
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Nonmotor symptoms in nursing home residents with Parkinsons disease: prevalence and effect on quality of life.
J Am Geriatr Soc
PUBLISHED: 10-01-2013
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To determine the prevalence of nonmotor symptoms (NMS) in nursing home (NH) residents with Parkinsons disease (PD) and to establish the association with quality of life.
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Defining the interaction of perforin with calcium and the phospholipid membrane.
Biochem. J.
PUBLISHED: 09-28-2013
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Following its secretion from cytotoxic lymphocytes into the immune synapse, perforin binds to target cell membranes through its Ca2+-dependent C2 domain. Membrane-bound perforin then forms pores that allow passage of pro-apoptopic granzymes into the target cell. In the present study, structural and biochemical studies reveal that Ca2+ binding triggers a conformational change in the C2 domain that permits four key hydrophobic residues to interact with the plasma membrane. However, in contrast with previous suggestions, these movements and membrane binding do not trigger irreversible conformational changes in the pore-forming MACPF (membrane attack complex/perforin-like) domain, indicating that subsequent monomer-monomer interactions at the membrane surface are required for perforin pore formation.
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Activation of Src family tyrosine kinases by ferric ions.
Biochim. Biophys. Acta
PUBLISHED: 09-06-2013
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The Src-family tyrosine kinases (SFKs) are oncogenic enzymes that contribute to the initiation and progression of many types of cancer. In normal cells, SFKs are kept in an inactive state mainly by phosphorylation of a consensus regulatory tyrosine near the C-terminus (Tyr(530) in the SFK c-Src). As recent data indicate that tyrosine modification enhances binding of metal ions, the hypothesis that SFKs might be regulated by metal ions was investigated. The c-Src C-terminal peptide bound two Fe(3+) ions with affinities at pH4.0 of 33 and 252?M, and phosphorylation increased the affinities at least 10-fold to 1.4 and 23?M, as measured by absorbance spectroscopy. The corresponding phosphorylated peptide from the SFK Lyn bound two Fe(3+) ions with much higher affinities (1.2pM and 160nM) than the Src C-terminal peptide. Furthermore, when Lyn or Hck kinases, which had been stabilised in the inactive state by phosphorylation of the C-terminal regulatory tyrosine, were incubated with Fe(3+) ions, a significant enhancement of kinase activity was observed. In contrast Lyn or Hck kinases in the unphosphorylated active state were significantly inhibited by Fe(3+) ions. These results suggest that Fe(3+) ions can regulate SFK activity by binding to the phosphorylated C-terminal regulatory tyrosine.
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The relationship between unmet care needs in young-onset dementia and the course of neuropsychiatric symptoms: a two-year follow-up study.
Int Psychogeriatr
PUBLISHED: 09-04-2013
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ABSTRACT Background: Little is known about care needs in young-onset dementia (YOD) patients, even though this information is essential for service provision and future care planning. We explored: (1) care needs of people with YOD, (2) the level of agreement within patient-caregiver dyads on care needs, and (3) the longitudinal relationship between unmet needs and neuropsychiatric symptoms. Methods: A community-based prospective study of 215 YOD patients-caregiver dyads. Care needs were assessed with the Camberwell Assessment of Need for the Elderly. The level of agreement between patient and caregivers report on care needs was calculated using ? coefficients. The relationship between unmet needs and neuropsychiatric symptoms over time, assessed with the Neuropsychiatric Inventory, was explored using linear mixed models. Results: Patients and caregivers generally agreed on the areas in which needs occurred. Only modest agreement existed within patient-caregiver dyads regarding whether needs could be met. Patients experienced high levels of unmet needs in areas such as daytime activities, social company, intimate relationships, and information, leading to an increase in neuropsychiatric symptoms. Conclusions: Our findings indicate that in YOD, there are specific areas of life in which unmet needs are more likely to occur. The high proportions of unmet needs and their relationship with neuropsychiatric symptoms warrant interventions that target neuropsychiatric symptoms as well as the prevention of unmet needs. This underlines the importance of the periodic investigation of care needs, in which patient and caregiver perspectives are considered complementary.
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More insight into the concept of apathy: a multidisciplinary depression management program has different effects on depressive symptoms and apathy in nursing homes.
Int Psychogeriatr
PUBLISHED: 09-02-2013
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Apathy is common in nursing home (NH) residents and it overlaps with depression. This study examines the effects of a multidisciplinary depression program on apathy and depressive motivational and mood symptoms.
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Cytoplasmic streaming in plant cells emerges naturally by microfilament self-organization.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 08-12-2013
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Many cells exhibit large-scale active circulation of their entire fluid contents, a process termed cytoplasmic streaming. This phenomenon is particularly prevalent in plant cells, often presenting strikingly regimented flow patterns. The driving mechanism in such cells is known: myosin-coated organelles entrain cytoplasm as they process along actin filament bundles fixed at the periphery. Still unknown, however, is the developmental process that constructs the well-ordered actin configurations required for coherent cell-scale flow. Previous experimental works on streaming regeneration in cells of Characean algae, whose longitudinal flow is perhaps the most regimented of all, hint at an autonomous process of microfilament self-organization driving the formation of streaming patterns during morphogenesis. Working from first principles, we propose a robust model of streaming emergence that combines motor dynamics with both microscopic and macroscopic hydrodynamics to explain how several independent processes, each ineffectual on its own, can reinforce to ultimately develop the patterns of streaming observed in the Characeae and other streaming species.
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White paper defining optimal palliative care in older people with dementia: A Delphi study and recommendations from the European Association for Palliative Care.
Palliat Med
PUBLISHED: 07-04-2013
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Background:Dementia is a life-limiting disease without curative treatments. Patients and families may need palliative care specific to dementia.Aim:To define optimal palliative care in dementia.Methods:Five-round Delphi study. Based on literature, a core group of 12 experts from 6 countries drafted a set of core domains with salient recommendations for each domain. We invited 89 experts from 27 countries to evaluate these in a two-round online survey with feedback. Consensus was determined according to predefined criteria. The fourth round involved decisions by the core team, and the fifth involved input from the European Association for Palliative Care.Results:A total of 64 (72%) experts from 23 countries evaluated a set of 11 domains and 57 recommendations. There was immediate and full consensus on the following eight domains, including the recommendations: person-centred care, communication and shared decision-making; optimal treatment of symptoms and providing comfort (these two identified as central to care and research); setting care goals and advance planning; continuity of care; psychosocial and spiritual support; family care and involvement; education of the health care team; and societal and ethical issues. After revision, full consensus was additionally reached for prognostication and timely recognition of dying. Recommendations on nutrition and dehydration (avoiding overly aggressive, burdensome or futile treatment) and on dementia stages in relation to care goals (applicability of palliative care) achieved moderate consensus.Conclusion:We have provided the first definition of palliative care in dementia based on evidence and consensus, a framework to provide guidance for clinical practice, policy and research.
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Domain structure and function of matrix metalloprotease 23 (MMP23): role in potassium channel trafficking.
Cell. Mol. Life Sci.
PUBLISHED: 06-18-2013
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MMP23 is a member of the matrix metalloprotease family of zinc- and calcium-dependent endopeptidases, which are involved in a wide variety of cellular functions. Its catalytic domain displays a high degree of structural homology with those of other metalloproteases, but its atypical domain architecture suggests that it may possess unique functional properties. The N-terminal MMP23 pro-domain contains a type-II transmembrane domain that anchors the protein to the plasma membrane and lacks the cysteine-switch motif that is required to maintain other MMPs in a latent state during passage to the cell surface. Instead of the C-terminal hemopexin domain common to other MMPs, MMP23 contains a small toxin-like domain (TxD) and an immunoglobulin-like cell adhesion molecule (IgCAM) domain. The MMP23 pro-domain can trap Kv1.3 but not closely-related Kv1.2 channels in the endoplasmic reticulum, preventing their passage to the cell surface, while the TxD can bind to the channel pore and block the passage of potassium ions. The MMP23 C-terminal IgCAM domain displays some similarity to Ig-like C2-type domains found in IgCAMs of the immunoglobulin superfamily, which are known to mediate protein-protein and protein-lipid interactions. MMP23 and Kv1.3 are co-expressed in a variety of tissues and together are implicated in diseases including cancer and inflammatory disorders. Further studies are required to elucidate the mechanism of action of this unique member of the MMP family.
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Dicarba ?-conotoxin Vc1.1 analogues with differential selectivity for nicotinic acetylcholine and GABAB receptors.
ACS Chem. Biol.
PUBLISHED: 06-17-2013
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Conotoxins have emerged as useful leads for the development of novel therapeutic analgesics. These peptides, isolated from marine molluscs of the genus Conus, have evolved exquisite selectivity for receptors and ion channels of excitable tissue. One such peptide, ?-conotoxin Vc1.1, is a 16-mer possessing an interlocked disulfide framework. Despite its emergence as a potent analgesic lead, the molecular target and mechanism of action of Vc1.1 have not been elucidated to date. In this paper we describe the regioselective synthesis of dicarba analogues of Vc1.1 using olefin metathesis. The ability of these peptides to inhibit acetylcholine-evoked current at rat ?9?10 and ?3?4 nicotinic acetylcholine receptors (nAChR) expressed in Xenopus oocytes has been assessed in addition to their ability to inhibit high voltage-activated (HVA) calcium channel current in isolated rat DRG neurons. Their solution structures were determined by NMR spectroscopy. Significantly, we have found that regioselective replacement of the native cystine framework with a dicarba bridge can be used to selectively tune the cyclic peptides innate biological activity for one receptor over another. The 2,8-dicarba Vc1.1 isomer retains activity at ?-aminobutyric acid (GABAB) G protein-coupled receptors, whereas the isomeric 3,16-dicarba Vc1.1 peptide retains activity at the ?9?10 nAChR subtype. These singularly acting analogues will enable the elucidation of the biological target responsible for the peptides potent analgesic activity.
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Parkinson Disease in Long Term Care Facilities: A Review of the Literature.
J Am Med Dir Assoc
PUBLISHED: 06-08-2013
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Parkinson disease (PD) is common in long term care (LTC) facilities. The number of institutionalized patients with PD will rise sharply in the coming decades because of 2 concurrent phenomena: aging of the population leads to an increased PD prevalence and improved quality of care has led to a prolonged survival in advanced disease stages. Only a few studies have investigated the prevalence and clinical characteristics of patients with PD in LTC facilities. Even fewer studies have addressed the treatment strategies used to support these institutionalized patients, who are mostly in advanced stages of the disease. The available evidence suggests that current management of patients with PD in LTC facilities is less than optimal. In the Netherlands, and we suspect in many other countries, there are no formal guidelines for treating patients with PD who have been admitted to a LTC facility. In this review, we describe the epidemiology, clinical characteristics, and clinical management of patients with PD in LTC settings. We also address potentially modifiable elements of care and provide several recommendations to improve the management of PD in these facilities. We conclude by suggesting a possible guide for future research in this area.
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Time use of stroke patients with stroke admitted for rehabilitation in Skilled Nursing Facilities.
Rehabil Nurs
PUBLISHED: 05-29-2013
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To describe the time use of patients with stroke in five Skilled Nursing Facilities (SNFs) in the Netherlands, focusing on the time spent on therapeutic activities, nontherapeutic activities, interaction with others, and the location where the activities took place. Evidence suggest that task-oriented interventions are the most effective for patients with stroke and that some of these interventions are relevant and feasible for use by nurses. The question arises to what extent elderly patients who had a stroke and rehabilitate in a SNF receive therapeutic training and engage in therapeutic activities.
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Awareness and its association with affective symptoms in young-onset and late-onset Alzheimer disease: a prospective study.
Alzheimer Dis Assoc Disord
PUBLISHED: 05-28-2013
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It is unknown whether there are differences between young-onset dementia and late-onset dementia in awareness levels and whether awareness is differentially associated with affective symptoms in both groups. The present study assesses possible differences between young-onset (YO-AD) and late-onset Alzheimer disease (LO-AD) in awareness levels and the association between awareness and affective symptoms.
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A structural multidisciplinary approach to depression management in nursing-home residents: a multicentre, stepped-wedge cluster-randomised trial.
Lancet
PUBLISHED: 05-02-2013
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Depression in nursing-home residents is often under-recognised. We aimed to establish the effectiveness of a structural approach to its management.
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Antiphase synchronization in a flagellar-dominance mutant of Chlamydomonas.
Phys. Rev. Lett.
PUBLISHED: 04-29-2013
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Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report the discovery that ptx1, a flagellar-dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. High-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wild-type. Possible mechanisms underlying these observations are discussed.
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Mammalian Neuronal Sodium Channel Blocker ?-Conotoxin BuIIIB Has a Structured N-Terminus That Influences Potency.
ACS Chem. Biol.
PUBLISHED: 04-16-2013
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Among the ?-conotoxins that block vertebrate voltage-gated sodium channels (VGSCs), some have been shown to be potent analgesics following systemic administration in mice. We have determined the solution structure of a new representative of this family, ?-BuIIIB, and established its disulfide connectivities by direct mass spectrometric collision induced dissociation fragmentation of the peptide with disulfides intact. The major oxidative folding product adopts a 1-4/2-5/3-6 pattern with the following disulfide bridges: Cys5-Cys17, Cys6-Cys23, and Cys13-Cys24. The solution structure reveals that the unique N-terminal extension in ?-BuIIIB, which is also present in ?-BuIIIA and ?-BuIIIC but absent in other ?-conotoxins, forms part of a short ?-helix encompassing Glu3 to Asn8. This helix is packed against the rest of the toxin and stabilized by the Cys5-Cys17 and Cys6-Cys23 disulfide bonds. As such, the side chain of Val1 is located close to the aromatic rings of Trp16 and His20, which are located on the canonical helix that displays several residues found to be essential for VGSC blockade in related ?-conotoxins. Mutations of residues 2 and 3 in the N-terminal extension enhanced the potency of ?-BuIIIB for NaV1.3. One analogue, [d-Ala2]BuIIIB, showed a 40-fold increase, making it the most potent peptide blocker of this channel characterized to date and thus a useful new tool with which to characterize this channel. On the basis of previous results for related ?-conotoxins, the dramatic effects of mutations at the N-terminus were unanticipated and suggest that further gains in potency might be achieved by additional modifications of this region.
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Strategies for the development of conotoxins as new therapeutic leads.
Mar Drugs
PUBLISHED: 04-14-2013
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Peptide toxins typically bind to their target ion channels or receptors with high potency and selectivity, making them attractive leads for therapeutic development. In some cases the native peptide as it is found in the venom from which it originates can be used directly, but in many instances it is desirable to truncate and/or stabilize the peptide to improve its therapeutic properties. A complementary strategy is to display the key residues that make up the pharmacophore of the peptide toxin on a non-peptidic scaffold, thereby creating a peptidomimetic. This review exemplifies these approaches with peptide toxins from marine organisms, with a particular focus on conotoxins.
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Confinement stabilizes a bacterial suspension into a spiral vortex.
Phys. Rev. Lett.
PUBLISHED: 04-10-2013
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Confining surfaces play crucial roles in dynamics, transport, and order in many physical systems, but their effects on active matter, a broad class of dynamically self-organizing systems, are poorly understood. We investigate here the influence of global confinement and surface curvature on collective motion by studying the flow and orientational order within small droplets of a dense bacterial suspension. The competition between radial confinement, self-propulsion, steric interactions, and hydrodynamics robustly induces an intriguing steady single-vortex state, in which cells align in inward spiraling patterns accompanied by a thin counterrotating boundary layer. A minimal continuum model is shown to be in good agreement with these observations.
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De novo design and synthesis of a ?-conotoxin KIIIA peptidomimetic.
Bioorg. Med. Chem. Lett.
PUBLISHED: 03-25-2013
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?-Conotoxin KIIIA blocks voltage-gated sodium channels and displays potent analgesic activity in mice models for pain. Structure-activity studies with KIIIA have shown that residues important for sodium channel activity are presented on an ?-helix. Herein, we report the de novo design and synthesis of a three-residue (Lys7, Trp8, His12) peptidomimetic based on a novel diketopiperazine (DKP) carboxamide scaffold.
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Fluid dynamics of bacterial turbulence.
Phys. Rev. Lett.
PUBLISHED: 02-21-2013
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Self-sustained turbulent structures have been observed in a wide range of living fluids, yet no quantitative theory exists to explain their properties. We report experiments on active turbulence in highly concentrated 3D suspensions of Bacillus subtilis and compare them with a minimal fourth-order vector-field theory for incompressible bacterial dynamics. Velocimetry of bacteria and surrounding fluid, determined by imaging cells and tracking colloidal tracers, yields consistent results for velocity statistics and correlations over 2 orders of magnitude in kinetic energy, revealing a decrease of fluid memory with increasing swimming activity and linear scaling between kinetic energy and enstrophy. The best-fit model allows for quantitative agreement with experimental data.
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A novel inhibitor of ?9?10 nicotinic acetylcholine receptors from Conus vexillum delineates a new conotoxin superfamily.
PLoS ONE
PUBLISHED: 01-30-2013
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Conotoxins (CTxs) selectively target a range of ion channels and receptors, making them widely used tools for probing nervous system function. Conotoxins have been previously grouped into superfamilies according to signal sequence and into families based on their cysteine framework and biological target. Here we describe the cloning and characterization of a new conotoxin, from Conus vexillum, named ?B-conotoxin VxXXIVA. The peptide does not belong to any previously described conotoxin superfamily and its arrangement of Cys residues is unique among conopeptides. Moreover, in contrast to previously characterized conopeptide toxins, which are expressed initially as prepropeptide precursors with a signal sequence, a pro region, and the toxin-encoding region, the precursor sequence of ?B-VxXXIVA lacks a pro region. The predicted 40-residue mature peptide, which contains four Cys, was synthesized in each of the three possible disulfide arrangements. Investigation of the mechanism of action of ?B-VxXXIVA revealed that the peptide is a nicotinic acetylcholine receptor (nAChR) antagonist with greatest potency against the ?9?10 subtype. (1)H nuclear magnetic resonance (NMR) spectra indicated that all three ?B-VxXXIVA isomers were poorly structured in aqueous solution. This was consistent with circular dichroism (CD) results which showed that the peptides were unstructured in buffer, but adopted partially helical conformations in aqueous trifluoroethanol (TFE) solution. The ?9?10 nAChR is an important target for the development of analgesics and cancer chemotherapeutics, and ?B-VxXXIVA represents a novel ligand with which to probe the structure and function of this protein.
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A general allometric and life-history model for cellular differentiation in the transition to multicellularity.
Am. Nat.
PUBLISHED: 01-28-2013
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The transition from unicellular, to colonial, to larger multicellular organisms has benefits, costs, and requirements. Here we present a model inspired by the volvocine green algae that explains the dynamics involved in the unicellular-multicellular transition using life-history theory and allometry. We model the two fitness components (fecundity and viability) and compare the fitness of hypothetical colonies of different sizes with varying degrees of cellular differentiation to understand the general principles that underlie the evolution of multicellularity. We argue that germ-soma separation may have evolved to counteract the increasing costs and requirements of larger multicellular colonies. The model shows that the cost of investing in soma decreases with size. For lineages such as the Volvocales, as reproduction costs increase with size for undifferentiated colonies, soma specialization benefits the colony indirectly by decreasing such costs and directly by helping reproductive cells acquire resources for their metabolic needs. Germ specialization is favored once soma evolves and takes care of vegetative functions. To illustrate the model, we use some allometric relationships measured in Volvocales. Our analysis shows that the cost of reproducing an increasingly larger group has likely played an important role in the transition to multicellularity and cellular differentiation.
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Membrane viscosity determined from shear-driven flow in giant vesicles.
Phys. Rev. Lett.
PUBLISHED: 01-14-2013
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The viscosity of lipid bilayer membranes plays an important role in determining the diffusion constant of embedded proteins and the dynamics of membrane deformations, yet it has historically proven very difficult to measure. Here we introduce a new method based on quantification of the large-scale circulation patterns induced inside vesicles adhered to a solid surface and subjected to simple shear flow in a microfluidic device. Particle image velocimetry based on spinning disk confocal imaging of tracer particles inside and outside of the vesicle and tracking of phase-separated membrane domains are used to reconstruct the full three-dimensional flow pattern induced by the shear. These measurements show excellent agreement with the predictions of a recent theoretical analysis, and allow direct determination of the membrane viscosity.
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Intracellular trafficking of the KV1.3 potassium channel is regulated by the prodomain of a matrix metalloprotease.
J. Biol. Chem.
PUBLISHED: 01-08-2013
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Matrix metalloproteases (MMPs) are endopeptidases that regulate diverse biological processes. Synthesized as zymogens, MMPs become active after removal of their prodomains. Much is known about the metalloprotease activity of these enzymes, but noncanonical functions are poorly defined, and functions of the prodomains have been largely ignored. Here we report a novel metalloprotease-independent, channel-modulating function for the prodomain of MMP23 (MMP23-PD). Whole-cell patch clamping and confocal microscopy, coupled with deletion analysis, demonstrate that MMP23-PD suppresses the voltage-gated potassium channel KV1.3, but not the closely related KV1.2 channel, by trapping the channel intracellularly. Studies with KV1.2-1.3 chimeras suggest that MMP23-PD requires the presence of the KV1.3 region from the S5 trans-membrane segment to the C terminus to modulate KV1.3 channel function. NMR studies of MMP23-PD reveal a single, kinked trans-membrane ?-helix, joined by a short linker to a juxtamembrane ?-helix, which is associated with the surface of the membrane and protected from exchange with the solvent. The topological similarity of MMP23-PD to KCNE1, KCNE2, and KCNE4 proteins that trap KV1.3, KV1.4, KV3.3, and KV3.4 channels early in the secretory pathway suggests a shared mechanism of channel regulation. MMP23 and KV1.3 expression is enhanced and overlapping in colorectal cancers where the interaction of the two proteins could affect cell function.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.