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Find video protocols related to scientific articles indexed in Pubmed.
Vascular access in the obese: superficialisation of native radio-cephalic and brachio-cephalic fistulae.
J Vasc Access
PUBLISHED: 10-16-2014
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The Department of Health estimates that currently in the UK, 61.3% of the population are overweight or obese (BMI gt;25 kg/m2). Fistulae in the obese often fail to mature or prove inadequate to needle due to excessive depth (gt;6 mm). This study is a summary of our experience with brachio and radio-cephalic vein superficialisation in the obese.
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Kinetics of Conformational Changes Revealed by Voltage-Clamp Fluorometry Give Insight to Desensitization at ATP-Gated Human P2X1 Receptors.
Mol. Pharmacol.
PUBLISHED: 10-08-2014
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ATP acts as an extracellular signaling molecule at cell-surface P2X receptors, mediating a variety of important physiologic and pathophysiologic roles. Homomeric P2X1 receptors open on binding ATP and then transition to an ATP-bound closed, desensitized state that requires an agonist-free washout period to recover. Voltage-clamp fluorometry was used to record ion channel activity and conformational changes simultaneously at defined positions in the extracellular loop of the human P2X1 receptor during not only agonist binding and desensitization but also during recovery. ATP evoked distinct conformational changes adjacent to the agonist binding pocket in response to channel activation and desensitization. The speed of recovery of the conformational change on agonist washout was state-dependent, with a faster time constant from the open (5 seconds) compared with the desensitized (75 seconds) form of the channel. The ability of ATP to evoke channel activity on washout after desensitization was not dependent on the degree of conformational rearrangement in the extracellular loop, and desensitization was faster from the partially recovered state. An intracellular mutation in the carboxyl terminus that slowed recovery of P2X1 receptor currents (7-fold less recovery at 30 seconds) had no effect on the time course of the extracellular conformational rearrangements. This study highlights that the intracellular portion of the receptor can regulate recovery and shows for the first time that this is by a mechanism independent of changes in the extracellular domain, suggesting the existence of a distinct desensitization gate in this novel class of ligand gated ion channels.
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P2X1 expressed on polymorphonuclear neutrophils and platelets is required for thrombosis in mice.
Blood
PUBLISHED: 08-22-2014
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Adenosine triphosphate (ATP) and its metabolite, adenosine, are key regulators of polymorphonuclear neutrophil (PMN) functions. PMNs have recently been implicated in the initiation of thrombosis. We investigated the role of ATP and adenosine in PMN activation and recruitment at the site of endothelial injury. Following binding to the injured vessel wall, PMNs are activated and release elastase. The recruitment of PMNs and the subsequent fibrin generation and thrombus formation are strongly affected in mice deficient in the P2X1-ATP receptor and in wild-type (WT) mice treated with CGS 21680, an agonist of the A2A adenosine receptor or NF449, a P2X1 antagonist. Infusion of WT PMNs into P2X1-deficient mice increases fibrin generation but not thrombus formation. Restoration of thrombosis requires infusion of both platelets and PMNs from WT mice. In vitro, ATP activates PMNs, whereas CGS 21680 prevents their binding to activated endothelial cells. These data indicate that adenosine triphosphate (ATP) contributes to polymorphonuclear neutrophil (PMN) activation leading to their adhesion at the site of laser-induced endothelial injury, a necessary step leading to the generation of fibrin, and subsequent platelet-dependent thrombus formation. Altogether, our study identifies previously unknown mechanisms by which ATP and adenosine are key molecules involved in thrombosis by regulating the activation state of PMNs.
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Ipsilateral cochlear implantation after cochlear nerve preserving vestibular schwannoma surgery in patients with neurofibromatosis type 2.
Otol. Neurotol.
PUBLISHED: 08-15-2014
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To investigate the outcomes from ipsilateral simultaneous or sequential cochlear implantation in patients with neurofibromatosis type 2 (NF2) after vestibular schwannoma removal with cochlear nerve preservation.
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Metastable ionic diodes derived from an amine-based polymer of intrinsic microporosity.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 08-11-2014
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A highly rigid amine-based polymer of intrinsic microporosity (PIM), prepared by a polymerization reaction involving the formation of Tröger's base, is demonstrated to act as an ionic diode with electrolyte-dependent bistable switchable states.
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Ca2+ influx through P2X1 receptors amplifies P2Y1 receptor-evoked Ca2+ signaling and ADP-evoked platelet aggregation.
Mol. Pharmacol.
PUBLISHED: 06-12-2014
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Many cells express both P2X cation channels and P2Y G-protein-coupled receptors that are costimulated by nucleotides released during physiologic or pathophysiologic responses. For example, during hemostasis and thrombosis, ATP-gated P2X1 channels and ADP-stimulated P2Y1 and P2Y12 G-protein coupled receptors play important roles in platelet activation. It has previously been reported that P2X1 receptors amplify P2Y1-evoked Ca(2+) responses in platelets, but the underlying mechanism and influence on function is unknown. In human platelets, we show that maximally activated P2X1 receptors failed to stimulate significant aggregation but could amplify the aggregation response to a submaximal concentration of ADP. Costimulation of P2X1 and P2Y1 receptors generated a superadditive Ca(2+) increase in both human platelets and human embryonic kidney 293 (HEK293) cells via a mechanism dependent on Ca(2+) influx rather than Na(+) influx or membrane depolarization. The potentiation, due to an enhanced P2Y1 response, was observed if ADP was added up to 60 seconds after P2X1 activation. P2X1 receptors also enhanced Ca(2+) responses when costimulated with type 1 protease activated and M1 muscarinic acetylcholine receptors. The P2X1-dependent amplification of Gq-coupled [Ca(2+)]i increase was mimicked by ionomycin and was not affected by inhibition of protein kinase C, Rho-kinase, or extracellular signal-regulated protein kinase 1/2, which suggests that it results from potentiation of inositol 1,4,5-trisphosphate receptors and/or phospholipase C. We conclude that Ca(2+) influx through P2X1 receptors amplifies Ca(2+) signaling through P2Y1 and other Gq-coupled receptors. This represents a general form of co-incidence detection of ATP and coreleased agonists, such as ADP at sites of vascular injury or synaptic transmitters acting at metabotropic Gq-coupled receptors.
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Development, comparison, and validation using ELISAs for the determination of domoic acid in California sea lion body fluids.
J AOAC Int
PUBLISHED: 05-17-2014
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Mortalities of California sea lions (Zalophus californianus) attributed to the neurotoxin domoic acid (DA) produced by the diatom Pseudo-nitzschia have occurred repeatedly along the U.S. west coast since the late 1990s. Quantifying the amount of DA in these animals and correlating this information with the presence of DA in phytoplankton and the local food web has become a research focus for many scientists. However, differences in materials, equipment, technical capability, budgets, and objectives of the various groups and/or agencies involved in this work have influenced the DA quantification platforms used. The goal of the present study was to compare the performance of two commercially available ELISAs for the determination of DA in a spectrum of California sea lion body fluids and to compare the results with LC/MS of the same samples. The results indicated differences among these approaches, presumably owing to matrix effects (particularly urine) and antibody reactivities. This information implies that care should be taken in attempting to compare datasets generated using different analytical platforms and interpreting the results of published studies.
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Risk factors and diagnostic accuracy of clinical findings for meniscal disease in dogs with cranial cruciate ligament disease.
Vet Surg
PUBLISHED: 04-01-2014
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To determine the risk factors for meniscal disease and diagnostic accuracy of physical examination in dogs with cranial cruciate ligament (CCL) deficiency.
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Myosin-Va and dynamic actin oppose microtubules to drive long-range organelle transport.
Curr. Biol.
PUBLISHED: 03-22-2014
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In animal cells, microtubule and actin tracks and their associated motors (dynein, kinesin, and myosin) are thought to regulate long- and short-range transport, respectively. Consistent with this, microtubules extend from the perinuclear centrosome to the plasma membrane and allow bidirectional cargo transport over long distances (>1 ?m). In contrast, actin often comprises a complex network of short randomly oriented filaments, suggesting that myosin motors move cargo short distances. These observations underpin the "highways and local roads" model for transport along microtubule and actin tracks. The "cooperative capture" model exemplifies this view and suggests that melanosome distribution in melanocyte dendrites is maintained by long-range transport on microtubules followed by actin/myosin-Va-dependent tethering. In this study, we used cell normalization technology to quantitatively examine the contribution of microtubules and actin/myosin-Va to organelle distribution in melanocytes. Surprisingly, our results indicate that microtubules are essential for centripetal, but not centrifugal, transport. Instead, we find that microtubules retard a centrifugal transport process that is dependent on myosin-Va and a population of dynamic F-actin. Functional analysis of mutant proteins indicates that myosin-Va works as a transporter dispersing melanosomes along actin tracks whose +/barbed ends are oriented toward the plasma membrane. Overall, our data highlight the role of myosin-Va and actin in transport, and not tethering, and suggest a new model in which organelle distribution is determined by the balance between microtubule-dependent centripetal and myosin-Va/actin-dependent centrifugal transport. These observations appear to be consistent with evidence coming from other systems showing that actin/myosin networks can drive long-distance organelle transport and positioning.
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Results of a pilot randomised controlled trial to measure the clinical and cost effectiveness of peer support in increasing hope and quality of life in mental health patients discharged from hospital in the UK.
BMC Psychiatry
PUBLISHED: 02-03-2014
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Mental health patients can feel anxious about losing the support of staff and patients when discharged from hospital and often discontinue treatment, experience relapse and readmission to hospital, and sometimes attempt suicide. The benefits of peer support in mental health services have been identified in a number of studies with some suggesting clinical and economic gains in patients being discharged.
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Triptycene induced enhancement of membrane gas selectivity for microporous Tröger's base polymers.
Adv. Mater. Weinheim
PUBLISHED: 01-30-2014
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A highly gas permeable polymer with exceptional size selectivity is prepared by fusing triptycene units together via a poly-merization reaction involving Tröger's base formation. The extreme rigidity of this polymer of intrinsic microporosity (PIM-Trip-TB) facilitates gas permeability data that lie well above the benchmark 2008 Robeson upper bounds for the important O2 /N2 and H2 /N2 gas pairs.
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Effect of total lens epithelial cell destruction on intraocular lens fixation in the human capsular bag.
J Cataract Refract Surg
PUBLISHED: 01-28-2014
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To evaluate the effect of complete destruction of lens epithelial cells (LECs) in the capsular bag on intraocular lens (IOL) stability.
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Habitat dynamics, marine reserve status, and the decline and recovery of coral reef fish communities.
Ecol Evol
PUBLISHED: 01-13-2014
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Severe climatic disturbance events often have major impacts on coral reef communities, generating cycles of decline and recovery, and in some extreme cases, community-level phase shifts from coral-to algal-dominated states. Benthic habitat changes directly affect reef fish communities, with low coral cover usually associated with low fish diversity and abundance. No-take marine reserves (NTRs) are widely advocated for conserving biodiversity and enhancing the sustainability of exploited fish populations. Numerous studies have documented positive ecological and socio-economic benefits of NTRs; however, the ability of NTRs to ameliorate the effects of acute disturbances on coral reefs has seldom been investigated. Here, we test these factors by tracking the dynamics of benthic and fish communities, including the important fishery species, coral trout (Plectropomus spp.), over 8?years in both NTRs and fished areas in the Keppel Island group, Great Barrier Reef, Australia. Two major disturbances impacted the reefs during the monitoring period, a coral bleaching event in 2006 and a freshwater flood plume in 2011. Both disturbances generated significant declines in coral cover and habitat complexity, with subsequent declines in fish abundance and diversity, and pronounced shifts in fish assemblage structure. Coral trout density also declined in response to the loss of live coral, however, the approximately 2:1 density ratio between NTRs and fished zones was maintained over time. The only post-disturbance refuges for coral trout spawning stocks were within the NTRs that escaped the worst effects of the disturbances. Although NTRs had little discernible effect on the temporal dynamics of benthic or fish communities, it was evident that the post-disturbance refuges for coral trout spawning stocks within some NTRs may be critically important to regional-scale population persistence and recovery.
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Introducing manganese complexes as redox mediators for dye-sensitized solar cells.
Phys Chem Chem Phys
PUBLISHED: 01-08-2014
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The abundance and low toxicity of manganese have led us to explore the application of manganese complexes as redox mediators for dye sensitized solar cells (DSCs), a promising solar energy conversion technology which mimics some of the key processes in photosynthesis during its operation. In this paper, we report the development of a DSC electrolyte based on the tris(acetylacetonato)manganese(iii)/(iv), [Mn(acac)3](0/1+), redox couple. PEDOT-coated FTO glass was used as a counter electrode instead of the conventionally used platinum. The influence of a number of device parameters on the DSC performance was studied, including the concentration of the reduced and oxidized mediator species, the concentration of specific additives (4-tert-butylpyridine, lithium tetrafluoroborate, and chenodeoxycholic acid) and the thickness of the TiO2 working electrode. These studies were carried out with a new donor-?-acceptor sensitizer K4. Maximum energy conversion efficiencies of 3.8% at simulated one Sun irradiation (AM 1.5 G; 1000 W m(-2)) with an open circuit voltage (VOC) of 765 mV, a short-circuit current (JSC) of 7.8 mA cm(-2) and a fill factor (FF) of 0.72 were obtained. Application of the commercially available MK2 and N719 sensitizers resulted in an energy conversion efficiency of 4.4% with a VOC of 733 mV and a JSC of 8.6 mA cm(-2) for MK2 and a VOC of 771 mV and a JSC of 7.9 mA cm(-2) for N719. Both dyes exhibit higher incident photon to current conversion efficiencies (IPCEs) than K4.
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Male contraception via simultaneous knockout of ?1A-adrenoceptors and P2X1-purinoceptors in mice.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 12-02-2013
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Therapeutic targets for male contraception are associated with numerous problems due to their focus on disrupting spermatogenesis or hormonal mechanisms to produce dysfunctional sperm. Here we describe the dual genetic deletion of ?1A-adrenergic G protein-coupled receptors (adrenoceptors) and P2X1-purinoceptor ligand gated ion channels in male mice, thereby blocking sympathetically mediated sperm transport through the vas deferens during the emission phase of ejaculation. This modification produced 100% infertility without effects on sexual behavior or function. Sperm taken from the cauda epididymides of double knockout mice were microscopically normal and motile. Furthermore, double knockout sperm were capable of producing normal offspring following intracytoplasmic sperm injection into wild-type ova and implantation of the fertilized eggs into foster mothers. Blood pressure and baroreflex function was reduced in double knockout mice, but no more than single knockout of ?1A-adrenoceptors alone. These results suggest that this autonomic method of male contraception appears free of major physiological and behavioral side effects. In addition, they provide conclusive proof of concept that pharmacological antagonism of the P2X1-purinoceptor and ?1A-adrenoceptor provides a safe and effective therapeutic target for a nonhormonal, readily reversible male contraceptive.
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Comparison of lateral fabellar suture and tibial plateau leveling osteotomy techniques for treatment of dogs with cranial cruciate ligament disease.
J. Am. Vet. Med. Assoc.
PUBLISHED: 08-27-2013
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To compare 1-year outcomes after lateral fabellar suture stabilization (LFS) and tibial plateau leveling osteotomy (TPLO) for the treatment of dogs with cranial cruciate ligament disease.
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Development of a P2X1-purinoceptor mediated contractile response in the aged mouse prostate gland through slowing down of ATP breakdown.
Neurourol. Urodyn.
PUBLISHED: 08-22-2013
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An age-related increase in prostatic smooth muscle tone is partly responsible for the lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH). Changes in the effectors of prostatic smooth muscle contraction with age may play a role in the development of these symptoms. Using a mouse model of prostate contractility, this study investigated the effect of age on the different components of contractility in the prostate gland.
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Comparison of the analgesic efficacy of perioperative firocoxib and tramadol administration in dogs undergoing tibial plateau leveling osteotomy.
J. Am. Vet. Med. Assoc.
PUBLISHED: 07-05-2013
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To evaluate the effects of perioperative oral administration of tramadol, firocoxib, and a tramadol-firocoxib combination on signs of pain and limb function after tibial plateau leveling osteotomy in dogs.
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Enhanced photovoltaic efficiency via light-triggered self-assembly.
Chem. Commun. (Camb.)
PUBLISHED: 06-14-2013
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Light-initiated, radical and hydrogen-bond induced self-assembly of bis-acetamido-functionalized triarylamines is demonstrated to occur in strongly dipolar "push-pull" molecules. This self-assembly process results in the formation of self-assembled nanostructures which in turn increase the efficiency of organic photovoltaic devices.
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P2X receptor chimeras highlight roles of the amino terminus to partial agonist efficacy, the carboxyl terminus to recovery from desensitization, and independent regulation of channel transitions.
J. Biol. Chem.
PUBLISHED: 06-05-2013
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P2X receptor subtypes can be distinguished by their sensitivity to ATP analogues and selective antagonists. We have used chimeras between human P2X1 and P2X2 receptors to address the contribution of the extracellular ligand binding loop, transmembrane segments (TM1 and TM2), and intracellular amino and carboxyl termini to the action of partial agonists (higher potency and efficacy of BzATP and Ap5A at P2X1 receptors) and antagonists. Sensitivity to the antagonists NF449, suramin, and PPADS was conferred by the nature of the extracellular loop (e.g. nanomolar for NF449 at P2X1 and P2X2-1EXT and micromolar at P2X2 and P2X1-2EXT). In contrast, the effectiveness of partial agonists was similar to P2X1 levels for both of the loop transfers, suggesting that interactions with the rest of the receptor played an important role. Swapping TM2 had reciprocal effects on partial agonist efficacy. However, TM1 swaps increased partial agonist efficacy at both chimeras, and this was similar for swaps of both TM1 and 2. Changing the amino terminus had no effect on agonist potency but increased partial agonist efficacy at P2X2-1N and decreased it at P2X1-2N chimeras, demonstrating that potency and efficacy can be independently regulated. Chimeras and point mutations also identified residues in the carboxyl terminus that regulated recovery from channel desensitization. These results show that interactions among the intracellular, transmembrane, and extracellular portions of the receptor regulate channel properties and suggest that transitions to channel opening, the behavior of the open channel, and recovery from the desensitized state can be controlled independently.
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Three-dimensional deep sub-diffraction optical beam lithography with 9 nm feature size.
Nat Commun
PUBLISHED: 05-28-2013
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The current nanofabrication techniques including electron beam lithography provide fabrication resolution in the nanometre range. The major limitation of these techniques is their incapability of arbitrary three-dimensional nanofabrication. This has stimulated the rapid development of far-field three-dimensional optical beam lithography where a laser beam is focused for maskless direct writing. However, the diffraction nature of light is a barrier for achieving nanometre feature and resolution in optical beam lithography. Here we report on three-dimensional optical beam lithography with 9?nm feature size and 52?nm two-line resolution in a newly developed two-photon absorption resin with high mechanical strength. The revealed dependence of the feature size and the two-line resolution confirms that they can reach deep sub-diffraction scale but are limited by the mechanical strength of the new resin. Our result has paved the way towards portable three-dimensional maskless laser direct writing with resolution fully comparable to electron beam lithography.
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Salvia officinalis for hot flushes: towards determination of mechanism of activity and active principles.
Planta Med.
PUBLISHED: 05-13-2013
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Herbal medicinal products are commonly used in alternative treatment of menopausal hot flushes. In a recent clinical study, Salvia officinalis tincture was found to reduce hot flush frequency and intensity. The aim of the current study was the investigation of the mechanism(s) responsible for the anti-hot flush activity of S. officinalis and determination of its active principle(s). The 66% ethanolic tincture, as well as the n-hexane, CHCl?, and aqueous ethanolic subextracts obtained from the tincture were studied in vitro for two of the most relevant activities, estrogenicity and selective serotonin reuptake inhibition. Because of an increased risk of menopausal women to suffer from Alzheimers disease, an in vitro acetylcholinesterase inhibition assay was also employed. No activity was observed in the selective serotonin reuptake inhibition or the acetylcholinesterase inhibition assays at the highest test concentrations. The tincture showed no estrogenic effects whereas the aqueous ethanolic subextract exhibited estrogenicity in the ERLUX assay with an EC?? value of 64 µg/mL. Estrogenic activity-guided fractionation of the aqueous ethanolic subextract by a combination of reverse-phase vacuum liquid chromatography and gel chromatography identified luteolin-7-O-glucuronide (EC?? 129 µg/mL) as the active component of the vacuum liquid chromatography fraction 4 (EC?? 69 µg/mL). Luteolin-7-O-glucoside was identified as the putative estrogenic principle of the most potent minor fraction (7.6.7.6, EC?? 0.7 µg/mL) obtained from the initial vacuum liquid chromatography fraction 7 (EC?? 3 µg/mL). This study suggests the involvement of common and ubiquitous estrogenic flavonoids in the anti-hot flush effect of Salvia officinalis, a safe and commonly used herbal medicinal product during the menopause.
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Short-term and long-term outcomes for overweight dogs with cranial cruciate ligament rupture treated surgically or nonsurgically.
J. Am. Vet. Med. Assoc.
PUBLISHED: 05-03-2013
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To determine short- and long-term rates of successful outcomes of surgical and nonsurgical treatments for overweight dogs with cranial cruciate ligament rupture (CCLR).
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Prevention of orthopaedic implant infection in patients undergoing dental procedures.
J Am Acad Orthop Surg
PUBLISHED: 03-05-2013
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The Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures evidence-based clinical practice guideline was codeveloped by the American Academy of Orthopaedic Surgeons (AAOS) and the American Dental Association. This guideline replaces the previous AAOS Information Statement, "Antibiotic Prophylaxis in Bacteremia in Patients With Joint Replacement," published in 2009. Based on the best current evidence and a systematic review of published studies, three recommendations have been created to guide clinical practice in the prevention of orthopaedic implant infections in patients undergoing dental procedures. The first recommendation is graded as Limited; this recommendation proposes that the practitioner consider changing the long-standing practice of routinely prescribing prophylactic antibiotic for patients with orthopaedic implants who undergo dental procedures. The second, graded as Inconclusive, addresses the use of oral topical antimicrobials in the prevention of periprosthetic joint infections. The third recommendation, a Consensus statement, addresses the maintenance of good oral hygiene.
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Glycogen function in adult central and peripheral nerves.
J. Neurosci. Res.
PUBLISHED: 01-24-2013
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We studied the roles of glycogen in axonal pathways of the central nervous system (CNS) and peripheral nervous system (PNS). By using electrophysiological recordings, in combination with biochemical glycogen assay, it was possible to determine whether glycogen was crucial to axon function under different conditions. Glycogen was present both in mouse optic nerve (MON) and in mouse sciatic nerve (MSN). Aglycemia caused loss of the compound action potential (CAP) in both pathways after a latency of 15 min (MON) and 120 min for myelinated axons (A fibers) in the MSN. With the exception of unmyelinated axons (C fibers) in the MSN, CAP decline began when usable glycogen was exhausted. Glycogen was located in astrocytes in the MON and in myelinating Schwann cells in the MSN; it was absent from the Schwann cells surrounding unmyelinated C fibers. In MON, astrocytic glycogen is metabolized to lactate and "shuttled" to axons to support metabolism. The ability of lactate to support A fiber conduction in the absence of glucose suggests a common pathway in both the CNS and the PNS. Lactate is released from MON and MSN in substantial quantities. That lactate levels fall in MSN in the presence of diaminobenzidine, which inhibits glycogen phosphorylase, strongly suggests that glycogen metabolism contributes to lactate release under resting conditions. Glycogen is a "backup" energy substrate in both the CNS and the PNS and, beyond sustaining excitability during glucose deprivation, has the capacity to subsidize the axonal energy demands during times of intense activity in the presence of glucose.
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Cyanomethylbenzoic acid: an acceptor for donor-?-acceptor chromophores used in dye-sensitized solar cells.
ChemSusChem
PUBLISHED: 01-23-2013
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Sensing the sun: Incorporation of a cyanomethyl benzoic acid electron acceptor into donor-?-acceptor sensitizers for dye-sensitized-solar cell is shown to lead to devices with improved conversion efficiency when compared with more widely used cyanoacetic acid acceptor.
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An efficient polymer molecular sieve for membrane gas separations.
Science
PUBLISHED: 01-19-2013
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Microporous polymers of extreme rigidity are required for gas-separation membranes that combine high permeability with selectivity. We report a shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units. The polymers contorted shape ensures both microporosity-with an internal surface area greater than 1000 square meters per gram-and solubility so that it is readily cast from solution into robust films. These films demonstrate exceptional performance as molecular sieves with high gas permeabilities and good selectivities for smaller gas molecules, such as hydrogen and oxygen, over larger molecules, such as nitrogen and methane. Hence, this polymer has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.
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Kin recognition affects plant communication and defence.
Proc. Biol. Sci.
PUBLISHED: 01-01-2013
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The ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviours; such ability is less well studied for plants. Many plants, including Artemisia tridentata, have been found to respond to volatile cues emitted by experimentally wounded neighbours to increase levels of resistance to herbivory. We report that this communication was more effective among A. tridentata plants that were more closely related based on microsatellite markers. Plants in the field that received cues from experimentally clipped close relatives experienced less leaf herbivory over the growing season than those that received cues from clipped neighbours that were more distantly related. These results indicate that plants can respond differently to cues from kin, making it less likely that emitters will aid strangers and making it more likely that receivers will respond to cues from relatives. More effective defence adds to a growing list of favourable consequences of kin recognition for plants.
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Metal-free and MRI visible theranostic lyotropic liquid crystal nitroxide-based nanoparticles.
Biomaterials
PUBLISHED: 11-18-2011
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The development of improved, low toxicity, clinically viable nanomaterials that provide MRI contrast have tremendous potential to form the basis of translatable theranostic agents. Herein we describe a class of MRI visible materials based on lyotropic liquid crystal nanoparticles loaded with a paramagnetic nitroxide lipid. These readily synthesized nanoparticles achieved enhanced proton-relaxivities on the order of clinically used gadolinium complexes such as Omniscan™ without the use of heavy metal coordination complexes. Their low toxicity, high water solubility and colloidal stability in buffer resulted in them being well tolerated in vitro and in vivo. The nanoparticles were initially screened in vitro for cytotoxicity and subsequently a defined concentration range was tested in rats to determine the maximum tolerated dose. Pharmacokinetic profiles of the candidate nanoparticles were established in vivo on IV administration to rats. The lyotropic liquid crystal nanoparticles were proven to be effective liver MRI contrast agents. We have demonstrated the effective in vivo performance of a T1 enhancing, biocompatible, colloidally stable, amphiphilic MRI contrast agent that does not contain a metal.
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The intracellular amino terminus plays a dominant role in desensitization of ATP-gated P2X receptor ion channels.
J. Biol. Chem.
PUBLISHED: 10-25-2011
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P2X receptors show marked variations in the time-course of response to ATP application from rapidly desensitizing P2X1 receptors to relatively sustained P2X2 receptors. In this study we have used chimeras between human P2X1 and P2X2 receptors in combination with mutagenesis to address the contribution of the extracellular ligand binding loop, the transmembrane channel, and the intracellular regions to receptor time-course. Swapping either the extracellular loop or both transmembrane domains (TM1 and -2) between the P2X1 and P2X2 receptors had no effect on the time-course of ATP currents in the recipient receptor. These results suggest that the agonist binding and channel-forming portions of the receptor do not play a major role in the control of the time-course. In contrast replacing the amino terminus of the P2X1 receptor with that from the non-desensitizing P2X2 receptor (P2X1-2N) slowed desensitization, and the mirror chimera induced rapid desensitization in the P2X2-1N chimera. These reciprocal effects on time-course can be replicated by changing four variant amino acids just before the first transmembrane (TM1) segment. These pre-TM1 residues also had a dominant effect on chimeras where both TMs had been transferred; mutating the variant amino acids 21-23 to those found in the P2X2 receptor removed desensitization from the P2X1-2TM1/-2 chimera, and the reciprocal mutants induced rapid desensitization in the non-desensitizing P2X2-1TM1/-2 chimera. These results suggest that the intracellular amino terminus, in particular the region just before TM1, plays a dominant role in the regulation of the time-course of ATP evoked P2X receptor currents.
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High-photosensitive resin for super-resolution direct-laser-writing based on photoinhibited polymerization.
Opt Express
PUBLISHED: 10-15-2011
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An ethoxylated bis-phenol-A dimethacrylate based photoresin BPE-100 of relatively high photosensitivity and modulus is used for the creation of sub-50 nm features. This is achieved by using the direct laser writing technique based on the single-photon photoinhibited polymerization. The super-resolution feature is realized by overlapping two laser beams of different wavelengths to enable the wavelength-controlled activation of photoinitiating and photoinhibiting processes in the polymerization. The increased photosensitivity of the photoresin promotes a fast curing speed and enhances the photopolymerization efficiency. Using the photoresin BPE-100, we achieve 40 nm dots for the first time in the super-resolution fabrication technique based on the photoinhibited polymerization, and a minimum linewidth of 130 nm. The influence of the power of the inhibiting laser and the exposure time on the feature size is studied and the results agree well with the prediction obtained from a simulation based on a non-steady-state kinetic model.
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Mechanical testing of orthopedic suture material used for extra-articular stabilization of canine cruciate ligament-deficient stifles.
Vet Surg
PUBLISHED: 09-23-2011
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To determine (1) if braided, polyblend orthopedic suture materials are mechanically superior to monofilament nylon leader and (2) have mechanical properties similar to biomechanical properties of the canine cruciate ligament.
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Effect of remote ischemic preconditioning on clinical outcomes in patients undergoing coronary artery bypass graft surgery (ERICCA): rationale and study design of a multi-centre randomized double-blinded controlled clinical trial.
Clin Res Cardiol
PUBLISHED: 08-30-2011
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Novel cardioprotective strategies are required to improve clinical outcomes in high risk patients undergoing coronary artery bypass graft (CABG) ± valve surgery. Remote ischemic preconditioning (RIC), in which brief episodes of non-lethal ischemia and reperfusion are applied to the arm or leg, has been demonstrated to reduce perioperative myocardial injury following CABG ± valve surgery. Whether RIC can improve clinical outcomes in this setting is unknown and is investigated in the effect of remote ischemic preconditioning on clinical outcomes (ERICCA) trial in patients undergoing CABG surgery. (ClinicalTrials.gov Identifier: NCT01247545).
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Using animal models in osteoarthritis biomarker research.
J Knee Surg
PUBLISHED: 08-11-2011
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Osteoarthritis (OA) is a disease that commonly affects human and veterinary patients. Animal models are routinely used for OA research, and the dog is a nearly ideal species for translational investigation of human OA biomarkers. The cytokine, chemokine, and matrix metalloprotease (MMP) profiles of synovial fluid, serum, and urine from dogs with surgically induced and naturally occurring OA were compared with dogs without OA using xMAP technology (Qiagen Inc., Valencia, CA). Markers that exhibited significant differences between groups were identified (monocyte chemoattractant protein 1 [MCP1], interleukin 8 [IL8], keratinocyte-derived chemoattractant [KC], and MMP2 and MMP3), and their sensitivities and specificities were calculated to determine their diagnostic usefulness in a future biomarker panel. Synovial fluid IL8 was the most sensitive, but MCP1 was also highly sensitive and specific. The alterations in KC suggested that it may differentiate between cruciate disease and other types of OA, and the MMPs were most sensitive and specific in the serum. This study provided additional insight to the participation of cytokines, chemokines, and MMPs in OA, and potential diagnostic biomarker candidates were identified. A brief literature review of other biomarker candidates previously examined using animal models is discussed.
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Identification of human P2X1 receptor-interacting proteins reveals a role of the cytoskeleton in receptor regulation.
J. Biol. Chem.
PUBLISHED: 07-07-2011
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P2X1 receptors are ATP-gated ion channels expressed by smooth muscle and blood cells. Carboxyl-terminally His-FLAG-tagged human P2X1 receptors were stably expressed in HEK293 cells and co-purified with cytoskeletal proteins including actin. Disruption of the actin cytoskeleton with cytochalasin D inhibited P2X1 receptor currents with no effect on the time course of the response or surface expression of the receptor. Stabilization of the cytoskeleton with jasplakinolide had no effect on P2X1 receptor currents but decreased receptor mobility. P2X2 receptor currents were unaffected by cytochalasin, and P2X1/2 receptor chimeras were used to identify the molecular basis of actin sensitivity. These studies showed that the intracellular amino terminus accounts for the inhibitory effects of cytoskeletal disruption similar to that shown for lipid raft/cholesterol sensitivity. Stabilization of the cytoskeleton with jasplakinolide abolished the inhibitory effects of cholesterol depletion on P2X1 receptor currents, suggesting that lipid rafts may regulate the receptor through stabilization of the cytoskeleton. These studies show that the cytoskeleton plays an important role in P2X1 receptor regulation.
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Cysteine scanning mutagenesis (residues Glu52-Gly96) of the human P2X1 receptor for ATP: mapping agonist binding and channel gating.
J. Biol. Chem.
PUBLISHED: 06-20-2011
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P2X receptors are ATP-gated cation channels. The x-ray structure of a P2X4 receptor provided a major advance in understanding the molecular basis of receptor properties. However, how agonists are coordinated, the extent of the binding site, and the contribution of the vestibules in the extracellular domain to ionic permeation have not been addressed. We have used cysteine-scanning mutagenesis to determine the contribution of residues Glu(52)-Gly(96) to human P2X1 receptor properties. ATP potency was reduced for the mutants K68C, K70C, and F92C. The efficacy of the partial agonist BzATP was also reduced for several mutants forming the back of the proposed agonist binding site. Molecular docking in silico of both ATP and BzATP provided models of the agonist binding site consistent with these data. Individual cysteine mutants had no effect or slightly increased antagonism by suramin or pyridoxal-phosphate-6-azophenyl-2,4-disulfonate. Mutants at the entrance to and lining the upper vestibule were unaffected by cysteine-reactive methanethiosulfonate (MTS) reagents, suggesting that it does not contribute to ionic permeation. Mutants that were sensitive to modification by MTS reagents were predominantly found either around the proposed ATP binding pocket or on the strands connecting the binding pocket to the transmembrane region and lining the central vestibule. In particular, ATP sensitivity and currents were increased by a positively charged MTS reagent at the G60C mutant at the interface between the central and extracellular vestibule. This suggests that dilation of the base of the central vestibule contributes to gating of the receptor.
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Current concepts for clean air and total joint arthroplasty: laminar airflow and ultraviolet radiation: a systematic review.
Clin. Orthop. Relat. Res.
PUBLISHED: 05-13-2011
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With the trend toward pay-for-performance standards plus the increasing incidence and prevalence of periprosthetic joint infection (PJI), orthopaedic surgeons must reconsider all potential infection control measures. Both airborne and nonairborne bacterial contamination must be reduced in the operating room.
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Surgical site infection prevention: the operating room environment.
Instr Course Lect
PUBLISHED: 05-11-2011
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Surgical site infections can complicate orthopaedic procedures and contribute to morbidity, mortality, and health care costs. Extensive literature has been published on this topic; however, the quality of data using standards of evidence-based medicine is variable with a lack of well-controlled studies. A review of the literature concerning measures to prevent surgical site infections in the operating room environment may be helpful in preventing such infections.
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Modifiable risk factors for surgical site infection.
Instr Course Lect
PUBLISHED: 05-11-2011
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Multiple risk factors for orthopaedic surgical site infection have been identified. Some of these factors directly affect the wound-healing process, whereas others can lead to blood-borne sepsis or relative immunosuppression. Modifying a patients medications; screening for comorbidities, such as HIV or diabetes mellitus; and advising the patient on options to diminish or eliminate adverse behaviors, such as smoking, should lower the risk for surgical site infections.
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Prophylactic antibiotics in orthopaedic surgery.
Instr Course Lect
PUBLISHED: 05-11-2011
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The use of prophylactic antibiotics in orthopaedic surgery has been proven effective in reducing surgical site infections after hip and knee arthroplasty, spine procedures, and open reduction and internal fixation of fractures. To maximize the beneficial effect of prophylactic antibiotics, while minimizing any adverse effects, the correct antimicrobial agent must be selected, the drug must be administered just before incision, and the duration of administration should not exceed 24 hours.
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Surgical site infection prevention and control: an emerging paradigm.
Instr Course Lect
PUBLISHED: 05-11-2011
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Examining the current state of infection in orthopaedic surgery provides tools and techniques to reduce the risks of nosocomial infections and prevent and treat infections from drug-resistant organisms. It is important for surgeons to recognize modifiable surgical risk factors and be aware of the importance of preoperative patient screening in reducing surgical site infections. The latest evidence-based data from scientific exhibits, instructional course lectures, and the Orthopaedic Knowledge Online continuing medical education module gathered during the past 5 years by the American Academy of Orthopaedic Surgeons Patient Safety Committee are useful in understanding and controlling the increasing and vital problem of surgical site infection.
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Vibrational properties of the disulfur dinitride molecule, S2N2: IR and Raman spectra of the matrix-isolated molecule.
J Phys Chem A
PUBLISHED: 04-29-2011
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The IR and Raman spectra of disulfur dinitride, S(2)N(2), are reported not only for the solid condensate but also for the molecules isolated in solid noble gas, N(2), or CH(4) matrices at low temperatures. The results imply that the isolated S(2)N(2) molecule has much the same geometry as in the crystalline solid with a virtually square-planar structure conforming to D(2h) symmetry, a conclusion confirmed by isotopic enrichment in (15)N and by the results of earlier as well as fresh quantum chemical calculations. These calculations also support the results of normal coordinate analysis of the experimental data in giving potential constants suggestive of a relatively rigid S(2)N(2) molecule consistent with its description as a 2?-electron aromatic, while appearing to maintain a formal S-N bond order close to 1.
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Experiencing patient-experience surveys: a qualitative study of the accounts of GPs.
Br J Gen Pract
PUBLISHED: 03-29-2011
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Despite policy and financial support for patient-experience surveys as feedback to modify clinical practice, their benefits and other effects remain unclear.
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Ex vivo biomechanical evaluation of the canine cranial cruciate ligament-deficient stifle with varying angles of stifle joint flexion and axial loads after tibial tuberosity advancement.
Vet Surg
PUBLISHED: 03-01-2011
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To evaluate the effect of tibial tuberosity advancement (TTA) on cranial tibial thrust (CrTT), retropatellar force (RPF), patellar tendon load (PTL), and patellar tendon angle determined by the tibial plateau angle (PTA(TPA) ) method or common tangent (PTA(CT) ) method in the canine cranial cruciate ligament (CrCL)-deficient stifle joint.
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The P2X1 receptor and platelet function.
Purinergic Signal.
PUBLISHED: 02-22-2011
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Extracellular nucleotides are ubiquitous signalling molecules, acting via the P2 class of surface receptors. Platelets express three P2 receptor subtypes, ADP-dependent P2Y1 and P2Y12 G-protein-coupled receptors and the ATP-gated P2X1 non-selective cation channel. Platelet P2X1 receptors can generate significant increases in intracellular Ca(2+), leading to shape change, movement of secretory granules and low levels of ?(IIb)?(3) integrin activation. P2X1 can also synergise with several other receptors to amplify signalling and functional events in the platelet. In particular, activation of P2X1 receptors by ATP released from dense granules amplifies the aggregation responses to low levels of the major agonists, collagen and thrombin. In vivo studies using transgenic murine models show that P2X1 receptors amplify localised thrombosis following damage of small arteries and arterioles and also contribute to thromboembolism induced by intravenous co-injection of collagen and adrenaline. In vitro, under flow conditions, P2X1 receptors contribute more to aggregate formation on collagen-coated surfaces as the shear rate is increased, which may explain their greater contribution to localised thrombosis in arterioles compared to venules within in vivo models. Since shear increases substantially near sites of stenosis, anti-P2X1 therapy represents a potential means of reducing thrombotic events at atherosclerotic plaques.
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Extracellular Ca(2+) modulates ADP-evoked aggregation through altered agonist degradation: implications for conditions used to study P2Y receptor activation.
Br. J. Haematol.
PUBLISHED: 02-20-2011
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ADP is considered a weak platelet agonist due to the limited aggregation responses it induces in vitro at physiological concentrations of extracellular Ca(2+) [(Ca(2+) )(o) ]. Lowering [Ca(2+) ](o) paradoxically enhances ADP-evoked aggregation, an effect that has been attributed to enhanced thromboxane A(2) production. This study examined the role of ectonucleotidases in the [Ca(2+) ](o) -dependence of platelet activation. Reducing [Ca(2+) ](o) from millimolar to micromolar levels converted ADP (10 ?mol/l)-evoked platelet aggregation from a transient to a sustained response in both platelet-rich plasma and washed suspensions. Blocking thromboxane A(2) production with aspirin had no effect on this [Ca(2+) ](o) -dependence. Prevention of ADP degradation abolished the differences between low and physiological [Ca(2+) ](o) resulting in a robust and sustained aggregation in both conditions. Measurements of extracellular ADP revealed reduced degradation in both plasma and apyrase-containing saline at micromolar compared to millimolar [Ca(2+) ](o) . As reported previously, thromboxane A(2) generation was enhanced at low [Ca(2+) ](o) , however this was independent of ectonucleotidase activity(.) P2Y receptor antagonists cangrelor and MRS2179 demonstrated the necessity of P2Y(12) receptors for sustained ADP-evoked aggregation, with a minor role for P2Y(1) . In conclusion, Ca(2+) -dependent ectonucleotidase activity is a major factor determining the extent of platelet aggregation to ADP and must be controlled for in studies of P2Y receptor activation.
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Polymer coatings that display specific biological signals while preventing nonspecific interactions.
J Biomed Mater Res A
PUBLISHED: 02-18-2011
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Control over cell-material surface interactions is the key to many new and improved biomedical devices. It can only be achieved if interactions that are mediated by nonspecifically adsorbed serum proteins are minimized and if cells instead respond to specific ligand molecules presented on the surface. Here, we present a simple yet effective surface modification method that allows for the covalent coupling and presentation of specific biological signals on coatings which have significantly reduced nonspecific biointerfacial interactions. To achieve this we synthesized bottle brush type copolymers consisting of poly(ethylene glycol) methyl ether methacrylate and (meth)acrylates providing activated NHS ester groups as well as different spacer lengths between the NHS groups and the polymer backbone. Copolymers containing different molar ratios of these monomers were grafted to amine functionalized polystyrene cell culture substrates, followed by the covalent immobilization of the cyclic peptides cRGDfK and cRADfK using residual NHS groups. Polymers were characterized by GPC and NMR and surface modification steps were analyzed using XPS. The cellular response was evaluated using HeLa cell attachment experiments. The results showed strong correlations between the effectiveness of the control over biointerfacial interactions and the polymer architecture. They also demonstrate that optimized fully synthetic copolymer coatings, which can be applied to a wide range of substrate materials, provide excellent control over biointerfacial interactions. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
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Extinction vulnerability of coral reef fishes.
Ecol. Lett.
PUBLISHED: 02-14-2011
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With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate.
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Multivariate analysis of morphometric characteristics to evaluate risk factors for cranial cruciate ligament deficiency in Labrador retrievers.
Vet Surg
PUBLISHED: 02-11-2011
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To determine the combination of conformation characteristics of the pelvic limbs of Labrador Retrievers that best discriminates between limb at risk to develop cranial cruciate ligament (CCL) disease and limbs at low risk using radiographs, computerized tomography (CT) images, and dual-energy X-ray absorptiometry (DEXA).
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Evaluation of S-adenosyl l-methionine in a double-blinded, randomized, placebo-controlled, clinical trial for treatment of presumptive osteoarthritis in the dog.
Vet Surg
PUBLISHED: 01-18-2011
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To evaluate the efficacy of S-adenosyl l-methionine (SAMe) in the treatment of clinically inferred canine osteoarthritis (OA).
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The dimer interface of the membrane type 1 matrix metalloproteinase hemopexin domain: crystal structure and biological functions.
J. Biol. Chem.
PUBLISHED: 12-30-2010
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Homodimerization is an essential step for membrane type 1 matrix metalloproteinase (MT1-MMP) to activate proMMP-2 and to degrade collagen on the cell surface. To uncover the molecular basis of the hemopexin (Hpx) domain-driven dimerization of MT1-MMP, a crystal structure of the Hpx domain was solved at 1.7 ? resolution. Two interactions were identified as potential biological dimer interfaces in the crystal structure, and mutagenesis studies revealed that the biological dimer possesses a symmetrical interaction where blades II and III of molecule A interact with blades III and II of molecule B. The mutations of amino acids involved in the interaction weakened the dimer interaction of Hpx domains in solution, and incorporation of these mutations into the full-length enzyme significantly inhibited dimer-dependent functions on the cell surface, including proMMP-2 activation, collagen degradation, and invasion into the three-dimensional collagen matrix, whereas dimer-independent functions, including gelatin film degradation and two-dimensional cell migration, were not affected. These results shed light on the structural basis of MT1-MMP dimerization that is crucial to promote cellular invasion.
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Diagnosis of periprosthetic joint infections of the hip and knee.
J Am Acad Orthop Surg
PUBLISHED: 12-02-2010
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No preferred test for diagnosis of periprosthetic joint infection exists, and the algorithm for the workup of patients suspected of infection remains unclear. The work group evaluated the available literature to determine the role of each diagnostic modality and devise a practical algorithm that allows physicians to reach diagnosis of periprosthetic joint infection. Ten of the 15 recommendations have strong or moderate evidence in support. These include matters involving erythrocyte sedimentation rate and C-reactive protein level testing, knee and hip aspiration, and stopping the use of antibiotics prior to obtaining intra-articular cultures. The group recommends against the use of intraoperative Gram stain but does recommend the use of frozen sections of peri-implant tissues in reoperation patients in whom infection has not been established, as well as multiple cultures in reoperation patients being assessed for infection. The group recommends against initiating antibiotic treatment in patients with suspected infection until after joint cultures have been obtained, but recommends that prophylactic preoperative antibiotics not be withheld in patients at lower probability for infection.
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Chemically-coupled-peptide-promoted virus nanoparticle templated mineralization.
Integr Biol (Camb)
PUBLISHED: 10-28-2010
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The external surface of the plant virus Cowpea mosaic virus (CPMV) can be chemically modified with peptides that direct specific mineralization processes. Subsequent mineralization of the peptide-CPMV conjugates produces monodisperse nanoparticles of ca. 32 nm diameter coated with, for example, cobalt-platinum, iron-platinum or zinc sulfide, which cannot be readily prepared by other methods. This route is particularly attractive as it avoids the need to genetically engineer the protein surface of the virus to provide chimaeras for templated-mineralization. The synthetic procedure is environmentally friendly, as it proceeds at ambient temperature and pressure, in aqueous solvent. Further, the methodology is demonstrated to be generally applicable by the mineralization of a peptide-modified multiwalled carbon nanotube.
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Structural interpretation of P2X receptor mutagenesis studies on drug action.
Br. J. Pharmacol.
PUBLISHED: 10-28-2010
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P2X receptors for ATP are ligand gated cation channels that form from the trimeric assembly of subunits with two transmembrane segments, a large extracellular ligand binding loop, and intracellular amino and carboxy termini. The receptors are expressed throughout the body, involved in functions ranging from blood clotting to inflammation, and may provide important targets for novel therapeutics. Mutagenesis based studies have been used to develop an understanding of the molecular basis of their pharmacology with the aim of developing models of the ligand binding site. A crystal structure for the zebra fish P2X4 receptor in the closed agonist unbound state has been published recently, which provides a major advance in our understanding of the receptors. This review gives an overview of mutagenesis studies that have led to the development of a model of the ATP binding site, as well as identifying residues contributing to allosteric regulation and antagonism. These studies are discussed with reference to the crystal to provide a structural interpretation of the molecular basis of drug action.
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Targeting of cancer cells using click-functionalized polymer capsules.
J. Am. Chem. Soc.
PUBLISHED: 10-26-2010
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Targeted delivery of drugs to specific cells allows a high therapeutic dose to be delivered to the target site with minimal harmful side effects. Combining targeting molecules with nanoengineered drug carriers, such as polymer capsules, micelles and polymersomes, has significant potential to improve the therapeutic delivery and index of a range of drugs. We present a general approach for functionalization of low-fouling, nanoengineered polymer capsules with antibodies using click chemistry. We demonstrate that antibody (Ab)-functionalized capsules specifically bind to colorectal cancer cells even when the target cells constitute less than 0.1% of the total cell population. This precise targeting offers promise for drug delivery applications.
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Carotid endarterectomy: a Southern North Island regional consensus statement.
N. Z. Med. J.
PUBLISHED: 10-09-2010
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The aim of this project was to employ interdepartmental and cross district health board collaboration to reach a regional consensus on the management of patients who may benefit from carotid endarterectomy.
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The residual nonadrenergic contractile response to nerve stimulation of the mouse prostate is mediated by acetylcholine but not ATP in a comparison with the mouse vas deferens.
J. Pharmacol. Exp. Ther.
PUBLISHED: 08-19-2010
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Neuronal release of noradrenaline is primarily responsible for the contraction of prostatic smooth muscle in all species, and this forms the basis for the use of ?(1)-adrenoceptor antagonists as pharmacotherapies for benign prostatic hyperplasia. Previous studies in mice have demonstrated that a residual nonadrenergic component to nerve stimulation remains after ?(1)-adrenoceptor antagonism. In the guinea pig and rat prostate and the vas deferens of guinea pigs, rats, and mice, ATP is the mediator of this residual contraction. This study investigates the mediator of residual contraction in the mouse prostate. Whole prostates from wild-type, ?(1A)-adrenoceptor, and P2X1-purinoceptor knockout mice were mounted in organ baths, and the isometric force that tissues developed in response to electrical field stimulation or exogenously applied agonists was recorded. Deletion of the P2X1 purinoceptor did not affect nerve-mediated contraction. Furthermore, the P2-purinoceptor antagonist suramin (30 ?M) failed to attenuate nerve-mediated contractions in wild-type, ?(1A)-adrenoceptor, or P2X1-purinoceptor knockout mice. Atropine (1 ?M) attenuated contraction in prostates taken from wild-type mice. In the presence of prazosin (0.3 ?M) or guanethidine (10 ?M), or in prostates taken from ?(1A)-adrenoceptor knockout mice, residual nerve-mediated contraction was abolished by atropine (1 ?M), but not suramin (30 ?M). Exogenously administered acetylcholine elicited reproducible concentration-dependent contractions of the mouse prostate that were atropine-sensitive (1 ?M), but not prazosin-sensitive (0.3 ?M). Acetylcholine, but not ATP, mediates the nonadrenergic component of contraction in the mouse prostate. This cholinergic component of prostatic contraction is mediated by activation of muscarinic receptors.
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Lipid raft association and cholesterol sensitivity of P2X1-4 receptors for ATP: chimeras and point mutants identify intracellular amino-terminal residues involved in lipid regulation of P2X1 receptors.
J. Biol. Chem.
PUBLISHED: 08-10-2010
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Cholesterol-rich lipid rafts act as signaling microdomains and can regulate receptor function. We have shown in HEK293 cells recombinant P2X1-4 receptors (ATP-gated ion channels) are expressed in lipid rafts. Localization to flotillin-rich lipid rafts was reduced by the detergent Triton X-100. This sensitivity to Triton X-100 was concentration- and subunit-dependent, demonstrating differential association of P2X1-4 receptors with lipid rafts. The importance of raft association to ATP-evoked P2X receptor responses was determined in patch clamp studies. The cholesterol-depleting agents methyl-?-cyclodextrin or filipin disrupt lipid rafts and reduced P2X1 receptor currents by >90%. In contrast, ATP-evoked P2X2-4 receptor currents were unaffected by lipid raft disruption. To determine the molecular basis of cholesterol sensitivity, we generated chimeric receptors replacing portions of the cholesterol-sensitive P2X1 receptor with the corresponding region from the insensitive P2X2 receptor. These chimeras identified the importance of the intracellular amino-terminal region between the conserved protein kinase C site and the first transmembrane segment for the sensitivity to cholesterol depletion. Mutation of any of the variant residues between P2X1 and P2X2 receptors in this region in the P2X1 receptor (residues 20-23 and 27-29) to cysteine removed cholesterol sensitivity. Cholesterol depletion did not change the ATP sensitivity or cell surface expression of P2X1 receptors. This suggests that cholesterol is normally needed to facilitate the opening/gating of ATP-bound P2X1 receptor channels, and mutations in the pre-first transmembrane segment region remove this requirement.
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CO2 triggering and controlling orthogonally multiresponsive photochromic systems.
J. Am. Chem. Soc.
PUBLISHED: 08-05-2010
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We report a new generic method of reversibly controlling the photochromism of spiropyrans. It was found that the photochromic effect of spiropyrans can be reversibly switched on and off by addition and removal of carbon dioxide (CO(2)) to spiropyran in alcohol solutions containing an amidine (i.e., DBU) that acts as a CO(2) sensitizer. Spiropyrans are not photochromic in the presence of DBU but photochromic when CO(2) is subsequently added to the solution. The CO(2) is readily removed by inert gas bubbling, thus allowing facile activation and deactivation of the photochromic effect. Carbon dioxide, without the presence of the sensitizing amidine, had no effect on photochromism of the spiropyrans. Other photochromic dyes classes such as spirooxazines and chromenes are not affected by this CO(2)/DBU stimulus. As a result, orthogonal activation of mixtures of spirooxazines and spiropyrans was achieved to provide four color states (clear, yellow, green, and blue) by varying the combinations of the stimuli of UV, visible light, CO(2), and CO(2) depleted. This finding now permits the many applications using spiropyrans to be CO(2) responsive.
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Serum cortisol concentration and force plate analysis in the assessment of pain associated with sodium urate-induced acute synovitis in dogs.
Am. J. Vet. Res.
PUBLISHED: 08-03-2010
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To determine the relationship between serum cortisol concentration and pain severity as measured by force platform gait analysis in dogs with experimentally induced synovitis of the stifle joint.
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Contribution of the intracellular C terminal domain to regulation of human P2X1 receptors for ATP by phorbol ester and Gq coupled mGlu(1?) receptors.
Eur. J. Pharmacol.
PUBLISHED: 08-02-2010
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P2X1 receptors are expressed in arteries and blood platelets, play an important role in the cardiovascular system, and their activity can be potentiated following stimulation of Gq coupled receptors or phorbol ester treatment. The contribution of the intracellular carboxy terminus of the P2X1 receptor to this regulation was determined using over-expression of the C terminus and a mutagenesis based approach on recombinant receptors expressed in Xenopus oocytes. PMA induced potentiation of P2X1 receptor currents (~125% above control) was abolished following over-expression of the intracellular carboxy terminus of the P2X1 receptor. To determine the molecular basis of regulation by the carboxy terminus a series of individual cysteine point mutations between His(355) and Tyr(370) was characterized. PMA potentiation was abolished for the P2X1 receptor mutants H355C, P358C, Y363C, K367C, F368C, K369C and Y370C. When these mutations were introduced into the carboxy terminus fragment the inhibitory effect was absent only for P358C, K367C and Y370C mutants. These results suggest that residues Pro(358), Lys(367) and Tyr(370) are involved in the sequestering effect of the carboxy terminal fragment and indicate they are directly involved in modulation of the receptor by binding to a regulatory factor. The other mutants that abolished the PMA effect when introduced into the P2X1 receptor are likely to be involved in transduction of the regulatory event. These studies highlight the importance of the carboxy terminus in determining the properties and regulation of the P2X1 receptor and suggest that the intracellular terminal regions of the receptor close to the transmembrane segments interact.
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Locked intramedullary fixation vs plating for displaced and shortened mid-shaft clavicle fractures: a randomized clinical trial.
J Shoulder Elbow Surg
PUBLISHED: 05-02-2010
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Recent literature supports surgical intervention for shortened, displaced, mid-shaft clavicle fractures. We present the results of a randomized clinical trial comparing locked intramedullary fixation and plate fixation for short, displaced, mid-shaft clavicle fractures.
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Severity of patellar luxation and frequency of concomitant cranial cruciate ligament rupture in dogs: 162 cases (2004-2007).
J. Am. Vet. Med. Assoc.
PUBLISHED: 04-16-2010
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To evaluate severity of medial patellar luxation (MPL) and frequency of concomitant cranial cruciate ligament rupture (CCLR) in dogs.
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Photochromic spirooxazines functionalized with oligomers: investigation of core-oligomer interactions and photomerocyanine isomer interconversion using NMR spectroscopy and DFT.
J. Org. Chem.
PUBLISHED: 04-14-2010
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Photochromic spirooxazines functionalized with poly(ethylene glycol) (PEG) and poly(dimethylsiloxane) (PDMS) oligomers were monitored using NMR spectroscopy at temperatures between 193 and 233 K before and after in situ exposure to UV irradiation. NOESY and ROESY experiments reveal the TTC (trans-s-trans-cis) isomer to be the dominant merocyanine isomer formed on photolysis, with some CTC (cis-s-trans-cis) isomer also present. Significant ROE cross peaks were observed between the "bulk" of the oligomeric units and protons across the entire photochromic core of the molecule, the intensity of these cross peaks suggesting that the interaction of the oligomer side chain and core of the molecule is significantly enhanced by the permanent attachment, especially with the PDMS side chain. The 2D NMR spectra indicate that there is exchange between the TTC and CTC isomers even at 193 K. This isomerization of the parent spirooxazine compounds, lacking the oligomeric side chains, was found to be acid-catalyzed, and DFT calculations support the strong possibility that it is the protonated merocyanine form that undergoes the facile isomerization process. Interconversion of the different merocyanine isomers is suggested to be fast on the NMR time scale under many experimental conditions, precluding the observation of different isomers using NMR spectroscopy at room temperature.
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P2X1 receptor mobility and trafficking; regulation by receptor insertion and activation.
J. Neurochem.
PUBLISHED: 04-02-2010
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P2X1 receptors for ATP contribute to signalling in a variety of cell types and following stimulation undergo rapid desensitisation (within 1 s), and require approximately 5 min to recover. In HEK293 cells P2X1 receptors C-terminally tagged with enhanced green fluorescent protein (P2X1-eGFP) were predominantly expressed at the cell surface. Following > 90% photo-bleaching of P2X1-eGFP within a 6 microm(2) circle at the cell surface fluorescence recovery after photo-bleaching (FRAP) was fit with a time constant of approximately 60 s and recovered to approximately 75% of pre-bleach levels. Following activation of the P2X1 receptor with alpha,beta-methylene ATP the associated calcium influx doubled the FRAP recovery rate. The protein synthesis inhibitor cycloheximide had only a small effect on repeated FRAP and indicated a limited contribution of new P2X1 receptors to the FRAP. Inhibition of trafficking with brefeldin A reduced recovery and this effect could be reversed following receptor activation. In contrast, the dynamin inhibitor dynasore had no effect on FRAP under unstimulated conditions but reduced the level of recovery following agonist stimulation. In functional studies both brefeldin A and dynasore increased the recovery time from desensitisation. Taken together these studies demonstrate for the first time an important role of receptor recycling on P2X1 receptor responsiveness.
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Pitfalls in the diagnosis of infection around the shoulder joint--report of three cases.
Bull NYU Hosp Jt Dis
PUBLISHED: 03-30-2010
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Infection around the shoulder joint is rare. Clinical suspicion and diagnostic imaging are required for accurate diagnosis. We present three cases that emphasise particular diagnostic challenges when dealing with infection around the shoulder joint. Discussion includes the role of ultrasound as a screening tool and the importance of magnetic resonance imaging (MRI) in the accurate diagnosis and localisation of infections around the shoulder.
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Adaptive management of the Great Barrier Reef: a globally significant demonstration of the benefits of networks of marine reserves.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 02-22-2010
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The Great Barrier Reef (GBR) provides a globally significant demonstration of the effectiveness of large-scale networks of marine reserves in contributing to integrated, adaptive management. Comprehensive review of available evidence shows major, rapid benefits of no-take areas for targeted fish and sharks, in both reef and nonreef habitats, with potential benefits for fisheries as well as biodiversity conservation. Large, mobile species like sharks benefit less than smaller, site-attached fish. Critically, reserves also appear to benefit overall ecosystem health and resilience: outbreaks of coral-eating, crown-of-thorns starfish appear less frequent on no-take reefs, which consequently have higher abundance of coral, the very foundation of reef ecosystems. Effective marine reserves require regular review of compliance: fish abundances in no-entry zones suggest that even no-take zones may be significantly depleted due to poaching. Spatial analyses comparing zoning with seabed biodiversity or dugong distributions illustrate significant benefits from application of best-practice conservation principles in data-poor situations. Increases in the marine reserve network in 2004 affected fishers, but preliminary economic analysis suggests considerable net benefits, in terms of protecting environmental and tourism values. Relative to the revenue generated by reef tourism, current expenditure on protection is minor. Recent implementation of an Outlook Report provides regular, formal review of environmental condition and management and links to policy responses, key aspects of adaptive management. Given the major threat posed by climate change, the expanded network of marine reserves provides a critical and cost-effective contribution to enhancing the resilience of the Great Barrier Reef.
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A non-linear regression analysis method for quantitative resolution of the stimulus-evoked compound action potential from rodent optic nerve.
J. Neurosci. Methods
PUBLISHED: 02-01-2010
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The stimulus-evoked compound action potential (CAP) recorded from rodent optic nerve is polyphasic in profile, with total area under the CAP an index of nerve function. A decrease in CAP area signifies a decrease in the number of axons contributing to the CAP. A disadvantage of considering the CAP a uniform entity is that any distinctions between the axon-subpopulations contributing to the individual peaks go undetected. We illustrate two instances that demonstrate the advantages of resolving the CAP into its constituent peaks. The individual peaks of the CAP were quantified using curve-fitting procedures to describe the CAP as the sum of multiple Gaussian functions. The first example illustrates that the individual peaks comprising the CAP exhibit differential sensitivities to glucopenia, suggesting that the axons within the nerve cannot be considered a homogeneous population with regard to their metabolic characteristics. The second example illustrates that the complex waveform of the CAP recorded from the optic nerve of the hypomyelinated rumpshaker mutant mouse, comprising both positive and negative overlapping peaks, can be resolved into five individual peaks. In conclusion we show that assessing each individual peak of the CAP is a powerful analytic tool for identifying heterogeneous profiles of axon-subpopulations in the rodent optic nerve.
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Bilateral glenohumeral septic arthritis secondary to retroperitoneal abscess.
Bull NYU Hosp Jt Dis
PUBLISHED: 12-17-2009
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Glenohumeral septic arthritis is rare and usually a result of Staphylococcus aureus infection. Gram-negative septic arthritis is on the increase and is usually associated with intraabdominal pathology. We present a case of bilateral E. Coli glenohumeral septic arthritis associated with retroperitoneal abscess and discuss pitfalls in diagnosis and management.
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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.