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1.
Biophys J ; 123(7): 824-838, 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38414237

RESUMEN

The binding of calcium/calmodulin (CAM) to calcium/calmodulin-dependent protein kinase II (CaMKII) initiates an ATP-driven cascade that triggers CaMKII autophosphorylation. The autophosphorylation in turn increases the CaMKII affinity for CAM. Here, we studied the ATP dependence of CAM association with the actin-binding CaMKIIß isoform using single-molecule total internal reflection fluorescence microscopy. Rhodamine-CAM associations/dissociations to surface-immobilized Venus-CaMKIIß were resolved with 0.5 s resolution from video records, batch-processed with a custom algorithm. CAM occupancy was determined simultaneously with spot-photobleaching measurement of CaMKII holoenzyme stoichiometry. We show the ATP-dependent increase of the CAM association requires dimer formation for both the α and ß isoforms. The study of mutant ß holoenzymes revealed that the ATP-dependent increase in CAM affinity results in two distinct states. The phosphorylation-defective (T287.306-307A) holoenzyme resides only in the low-affinity state. CAM association is further reduced in the T287A holoenzyme relative to T287.306-307A. In the absence of ATP, the affinity of CAM for the T287.306-307A mutant and the wild-type monomer are comparable. The affinity of the ATP-binding impaired (K43R) mutant is even weaker. In ATP, the K43R holoenzyme resides in the low-affinity state. The phosphomimetic mutant (T287D) resides only in a 1000-fold higher-affinity state, with mean CAM occupancy of more than half of the 14-mer holoenzyme stoichiometry in picomolar CAM. ATP promotes T287D holoenzyme disassembly but does not elevate CAM occupancy. Single Poisson distributions characterized the ATP-dependent CAM occupancy of mutant holoenzymes. In contrast, the CAM occupancy of the wild-type population had a two-state distribution with both low- and high-affinity states represented. The low-affinity state was the dominant state, a result different from published in vitro assays. Differences in assay conditions can alter the balance between activating and inhibitory autophosphorylation. Bound ATP could be sufficient for CaMKII structural function, while antagonistic autophosphorylations may tune CaMKII kinase-regulated action-potential frequency decoding in vivo.


Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina , Calmodulina , Calmodulina/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/química , Calcio/metabolismo , Imagen Individual de Molécula , Adenosina Trifosfato/metabolismo , Holoenzimas/química , Holoenzimas/metabolismo , Fosforilación
2.
Mol Cell ; 62(1): 21-33, 2016 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-27058785

RESUMEN

The inhibitory function of killer cell immunoglobulin-like receptors (KIR) that bind HLA-C and block activation of human natural killer (NK) cells is dependent on zinc. We report that zinc induced the assembly of soluble KIR into filamentous polymers, as detected by electron microscopy, which depolymerized after zinc chelation. Similar KIR filaments were isolated from lysates of cells treated with zinc, and membrane protrusions enriched in zinc were detected on whole cells by scanning electron microscopy and imaging mass spectrometry. Two independent mutations in the extracellular domain of KIR, away from the HLA-C binding site, impaired zinc-driven polymerization and inhibitory function. KIR filaments formed spontaneously, without the addition of zinc, at functional inhibitory immunological synapses of NK cells with HLA-C(+) cells. Adding to the recent paradigm of signal transduction through higher order molecular assemblies, zinc-induced polymerization of inhibitory KIR represents an unusual mode of signaling by a receptor at the cell surface.


Asunto(s)
Células Asesinas Naturales/inmunología , Receptores KIR/química , Receptores KIR/metabolismo , Zinc/farmacología , Células Cultivadas , Células HEK293 , Antígenos HLA/metabolismo , Humanos , Sinapsis Inmunológicas/metabolismo , Polimerizacion , Receptores KIR/genética , Transducción de Señal
3.
BMC Med Educ ; 24(1): 468, 2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38671395

RESUMEN

BACKGROUND: Individuals from minority groups have historically faced social injustices. Those from underrepresented groups have been less likely to access both healthcare services and higher education. Little is known about the experiences of underrepresented students during their undergraduate studies in osteopathy in the UK. The aim of this project was to explore awareness of cultural diversity and beliefs about patients from underrepresented groups in current osteopathic educational environments and evaluate students' preparedness to manage patients from diverse groups. The project also aimed to investigate the educational experiences of students from underrepresented backgrounds during their training and their opinions on changes that could support better levels of recruitment and achievement. The findings were discussed with stakeholders in interactive workshops with the aim to develop recommendations for action and change. METHODS: A transformative action research paradigm informed this mixed methods project. It included: 1/ a survey of students from all seven osteopathic educational providers in the UK using the Multidimensional Cultural Humility Scale (MCHS); 2/ a series of focus groups with students from underrepresented groups (women, students with disabilities, students from minority ethnic backgrounds, and students identifying as LGBTQIA+); and 3/ a workshop forum to discuss findings. RESULTS: A total of 202 participants completed the MCHS and demographic questionnaire and seven focus groups were conducted. A model was developed to describe participants' training experiences comprising two main themes: institutional contextual obstacles (with four sub-themes) and underrepresented students' conceptual understanding of Equity, Diversity and Inclusion (EDI). Recommendations for change identified in the workshops were based on three topics: institutions, staff, and students. CONCLUSION: Our findings confirm conclusions from other institutions that staff education is urgently needed to create and maintain equitable, inclusive environments in osteopathic educational institutions in the UK to support all students, particularly those from underrepresented groups. Institutional EDI processes and policies also need to be clarified or modified to ensure their usefulness, accessibility, and implementation.


Asunto(s)
Diversidad Cultural , Grupos Focales , Grupos Minoritarios , Medicina Osteopática , Humanos , Medicina Osteopática/educación , Femenino , Masculino , Reino Unido , Estudiantes de Medicina/psicología , Adulto , Encuestas y Cuestionarios , Adulto Joven
4.
Am J Respir Cell Mol Biol ; 69(4): 391-403, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37290041

RESUMEN

Acute respiratory distress syndrome (ARDS) is a lung disease characterized by acute onset of noncardiogenic pulmonary edema, hypoxemia, and respiratory insufficiency. The current treatment for ARDS is mainly supportive in nature, providing a critical need for targeted pharmacological management. We addressed this medical problem by developing a pharmacological treatment for pulmonary vascular leakage, a culprit of alveolar damage and lung inflammation. Our novel therapeutic target is the microtubule accessory factor EB3 (end binding protein 3), which contributes to pulmonary vascular leakage by amplifying pathological calcium signaling in endothelial cells in response to inflammatory stimuli. EB3 interacts with IP3R3 (inositol 1,4,5-trisphosphate receptor 3) and orchestrates calcium release from endoplasmic reticulum stores. Here, we designed and tested the therapeutic benefits of a 14-aa peptide named CIPRI (cognate IP3 receptor inhibitor), which disrupted EB3-IP3R3 interaction in vitro and in lungs of mice challenged with endotoxin. Treatment with CIPRI or depletion of IP3R3 in lung microvascular endothelial monolayers mitigated calcium release from endoplasmic reticulum stores and prevented a disassembly of vascular endothelial cadherin junctions in response to the proinflammatory mediator α-thrombin. Furthermore, intravenous administration of CIPRI in mice mitigated inflammation-induced lung injury, blocked pulmonary microvascular leakage, prevented activation of NFAT (nuclear factor of activated T cells) signaling, and reduced production of proinflammatory cytokines in the lung tissue. CIPRI also improved survival of mice from endotoxemia and polymicrobial sepsis. Together, these data demonstrate that targeting EB3-IP3R3 interaction with a cognate peptide is a promising strategy to address hyperpermeability of microvessels in inflammatory lung diseases.


Asunto(s)
Edema Pulmonar , Síndrome de Dificultad Respiratoria , Ratones , Animales , Células Endoteliales/metabolismo , Calcio/metabolismo , Síndrome de Dificultad Respiratoria/metabolismo , Pulmón/patología , Edema Pulmonar/patología , Proteínas Portadoras/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo
5.
Phys Chem Chem Phys ; 25(29): 19532-19539, 2023 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-37351579

RESUMEN

Advances in ultra-fast photonics have enabled monitoring of biochemical interactions on a sub nano-second time scale. In addition, picosecond dynamics of intermolecular energy transfer in fluorescent proteins has been observed. Here, we present the development of a genetically encoded fluorescent sensor that can detect changes in hydrophobicity by monitoring ultrafast fluorescence depolarisation. Our sensor is composed of a pair of dimeric enhanced green fluorescent proteins (dEGFPs) linked by a flexible amino-acid linker. We show dimerisation is perturbed by the addition of glycerol which interferes with the hydrophobic interaction of the two proteins. Time-resolved fluorescence anisotropy revealed a systematic attenuation of ultrafast fluorescence depolarisation when the sensor was exposed to increasing glycerol concentrations. This suggests that as hydrophobicity increases, dEGFP pairing decreases within a tandem dimer. Un-pairing of the protein fluorophores dramatically alters the rate of energy transfer between the proteins, resulting in an increase in the limiting anisotropy of the sensor.


Asunto(s)
Glicerol , Polímeros , Proteínas Fluorescentes Verdes/química , Espectrometría de Fluorescencia , Interacciones Hidrofóbicas e Hidrofílicas , Transferencia Resonante de Energía de Fluorescencia/métodos , Polarización de Fluorescencia
6.
Schmerz ; 37(5): 360-371, 2023 Oct.
Artículo en Alemán | MEDLINE | ID: mdl-35834004

RESUMEN

INTRODUCTION: Remote consultations through phone or video are gaining in importance for the treatment of musculoskeletal pain across a range of health care providers. However, there is a plethora of technical options for practitioners to choose from, and there are various challenges in the adaptation of clinical processes as well as several special considerations regarding regulatory context and patient management. Practitioners are faced with a lack of high-quality peer-reviewed resources to guide the planning and practical implementation of remote consultations. OBJECTIVES: This Clinical Update seeks to provide practical guidance for the planning and implementation of remote consultations for the management and treatment of people with musculoskeletal pain. METHODS: Recommendations are based on a brief overview of the relevant research regarding phone and video consultations for musculoskeletal practice and derived from the literature, relevant guidelines, and practical experience. RESULTS: The technical feasibility of remote consultations for musculoskeletal complaints is good, patient satisfaction is high, and a growing body of evidence supports its comparative effectiveness to in-person consultations in some circumstances for improving pain and functioning. We consider in detail practical aspects such as the choosing of hardware and software, we touch on the legal and regulatory context, and we focus on the adaptation of clinical processes and communication. CONCLUSION: This Clinical Update draws together best-practice evidence in a practically applicable format, enabling therapists who are working with people with pain to directly apply this knowledge to their individual clinical settings and the requirements of their patients.


Asunto(s)
Dolor Musculoesquelético , Consulta Remota , Humanos , Dolor Musculoesquelético/diagnóstico , Dolor Musculoesquelético/terapia
7.
Nat Methods ; 16(9): 815-829, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31471616

RESUMEN

The applications of Förster resonance energy transfer (FRET) grow with each year. However, different FRET techniques are not applied consistently, nor are results uniformly presented, which makes implementing and reproducing FRET experiments challenging. We discuss important considerations for designing and evaluating ensemble FRET experiments. Alongside a primer on FRET basics, we provide guidelines for making experimental design choices such as the donor-acceptor pair, instrumentation and labeling chemistries; selecting control experiments to unambiguously demonstrate FRET and validate that the experiments provide meaningful data about the biomolecular process in question; analyzing raw data and assessing the results; and reporting data and experimental details in a manner that easily allows for reproducibility. Some considerations are also given for FRET assays and FRET imaging, especially with fluorescent proteins. Our goal is to motivate and empower all biologists to consider FRET for the powerful research tool it can be.


Asunto(s)
Investigación Biomédica , Transferencia Resonante de Energía de Fluorescencia/métodos , Colorantes Fluorescentes/química , Proteínas Luminiscentes/metabolismo , Imagen Molecular/métodos , Animales , Humanos
8.
Biophys J ; 116(10): 1918-1930, 2019 05 21.
Artículo en Inglés | MEDLINE | ID: mdl-31060812

RESUMEN

Fluorescent proteins (FPs) have revolutionized cell biology by allowing genetic tagging of specific proteins inside living cells. In conjunction with Förster's resonance energy transfer (FRET) measurements, FP-tagged proteins can be used to study protein-protein interactions and estimate distances between tagged proteins. FRET is mediated by weak Coulombic dipole-dipole coupling of donor and acceptor fluorophores that behave independently, with energy hopping discretely and incoherently between fluorophores. Stronger dipole-dipole coupling can mediate excitonic coupling in which excitation energy is distributed near instantaneously between coherently interacting excited states that behave as a single quantum entity. The interpretation of FP energy transfer measurements to estimate separation often assumes that donors and acceptors are very weakly coupled and therefore use a FRET mechanism. This assumption is considered reasonable as close fluorophore proximity, typically associated with strong excitonic coupling, is limited by the FP ß-barrel structure. Furthermore, physiological temperatures promote rapid vibrational dephasing associated with a rapid decoherence of fluorophore-excited states. Recently, FP dephasing times that are 50 times slower than traditional organic fluorophores have been measured, raising the possibility that evolution has shaped FPs to allow stronger than expected coupling under physiological conditions. In this study, we test if excitonic coupling between FPs is possible at physiological temperatures. FRET and excitonic coupling can be distinguished by monitoring spectral changes associated with fluorophore dimerization. The weak coupling mediating FRET should not cause a change in fluorophore absorption, whereas strong excitonic coupling causes Davydov splitting. Circular dichroism spectroscopy revealed Davydov splitting when the yellow FP VenusA206 dimerizes, and a novel approach combining photon antibunching and fluorescence correlation spectroscopy was used to confirm that the two fluorophores in a VenusA206 homodimer behave as a single-photon emitter. We conclude that excitonic coupling between VenusA206 fluorophores is possible at physiological temperatures.


Asunto(s)
Proteínas Luminiscentes/química , Multimerización de Proteína , Temperatura , Células HEK293 , Humanos , Modelos Moleculares , Estructura Cuaternaria de Proteína
9.
Nature ; 494(7436): 238-42, 2013 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-23354054

RESUMEN

The basal ganglia are subcortical nuclei that control voluntary actions, and they are affected by a number of debilitating neurological disorders. The prevailing model of basal ganglia function proposes that two orthogonal projection circuits originating from distinct populations of spiny projection neurons (SPNs) in the striatum--the so-called direct and indirect pathways--have opposing effects on movement: activity of direct-pathway SPNs is thought to facilitate movement, whereas activity of indirect-pathway SPNs is presumed to inhibit movement. This model has been difficult to test owing to the lack of methods to selectively measure the activity of direct- and indirect-pathway SPNs in freely moving animals. Here we develop a novel in vivo method to specifically measure direct- and indirect-pathway SPN activity, using Cre-dependent viral expression of the genetically encoded calcium indicator (GECI) GCaMP3 in the dorsal striatum of D1-Cre (direct-pathway-specific) and A2A-Cre (indirect-pathway-specific) mice. Using fibre optics and time-correlated single-photon counting (TCSPC) in mice performing an operant task, we observed transient increases in neural activity in both direct- and indirect-pathway SPNs when animals initiated actions, but not when they were inactive. Concurrent activation of SPNs from both pathways in one hemisphere preceded the initiation of contraversive movements and predicted the occurrence of specific movements within 500 ms. These observations challenge the classical view of basal ganglia function and may have implications for understanding the origin of motor symptoms in basal ganglia disorders.


Asunto(s)
Movimiento/fisiología , Neostriado/citología , Neostriado/fisiología , Vías Nerviosas/fisiología , Animales , Señalización del Calcio , Femenino , Tecnología de Fibra Óptica/métodos , Fluorescencia , Integrasas/genética , Integrasas/metabolismo , Mediciones Luminiscentes/métodos , Masculino , Ratones , Modelos Neurológicos , Enfermedad de Parkinson , Fotones
11.
Biophys J ; 112(6): 1270-1281, 2017 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-28355553

RESUMEN

While kinases are typically composed of one or two subunits, calcium-calmodulin (CaM)-dependent protein kinase II (CaMKII) is composed of 8-14 subunits arranged as pairs around a central core. It is not clear if the CaMKII holoenzyme functions as an assembly of independent subunits, as catalytic pairs, or as a single unit. One strategy to address this question is to genetically engineer monomeric and dimeric CaMKII and evaluate how their activity compares to the wild-type (WT) holoenzyme. Here a technique that combines fluorescence correlation spectroscopy and homo-FRET analysis was used to characterize assembly mutants of Venus-tagged CaMKIIα to identify a dimeric CaMKII. Spectroscopy was then used to compare how holoenzyme structure and function changes in response to activation with CaM in the dimeric mutant, WT-holoenzyme, and a monomeric CaMKII oligomerization-domain deletion mutant control. CaM triggered an increase in hydrodynamic volume in both WT and dimeric CaMKII without altering subunit stoichiometry or the net homo-FRET between Venus-tagged catalytic domains. Biochemical analysis revealed that the dimeric mutant also functioned like WT holoenzyme in terms of its kinase activity with an exogenous substrate, and for endogenous T286 autophosphorylation. We conclude that the fundamental functional units of CaMKII holoenzyme are paired catalytic-domains.


Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/química , Transferencia Resonante de Energía de Fluorescencia , Multimerización de Proteína , Células HEK293 , Holoenzimas/química , Humanos , Estructura Cuaternaria de Proteína
12.
J Immunol ; 194(2): 817-26, 2015 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-25505289

RESUMEN

Signaling by immunoreceptors is often initiated by phosphorylation of cytosolic tyrosines, which then recruit effector molecules. In the case of MHC class I-specific inhibitory receptors, phosphorylation of cytosolic tyrosine residues within ITIMs results in recruitment of a protein tyrosine phosphatase that blocks activation signals. Recent work showed that signaling by an HLA-C-specific killer cell Ig-like receptor (KIR) is independent of signaling by activation receptors. It is not known how ITIM phosphorylation is initiated and regulated. In this article, we show that substitution of His-36 in the first Ig domain of KIR2DL1 with alanine (KIR2DL1-H36A) resulted in constitutive KIR2DL1 self-association and phosphorylation, as well as recruitment of tyrosine phosphatase SHP-1. Furthermore, substitution of His-36 with a similar bulky amino acid, phenylalanine, maintained the receptor in its unphosphorylated state, suggesting that steric hindrance by the His-36 side chain prevents constitutive KIR2DL1 self-association and ITIM phosphorylation. The equally strong phosphorylation of KIR2DL1 and KIR2DL1-H36A after inhibition of tyrosine phosphatase by pervanadate suggested that KIR2DL1-H36A is selectively protected from dephosphorylation. We propose that KIR phosphorylation is controlled by the accessibility of ITIM to tyrosine phosphatases and that KIR binding to HLA-C must override the hindrance that His-36 puts on KIR2DL1 self-association. Expression of KIR2DL1-H36A on NK cells led to stronger inhibition of lysis of HLA-C(+) target cells than did expression of wild-type KIR2DL1. These results revealed that ITIM phosphorylation is controlled by self-association of KIR and that His-36 serves as a gatekeeper to prevent unregulated signaling through KIR2DL1.


Asunto(s)
Sustitución de Aminoácidos/inmunología , Antígenos HLA-C , Células Asesinas Naturales/inmunología , Proteína Tirosina Fosfatasa no Receptora Tipo 6 , Receptores KIR2DL1 , Transducción de Señal , Línea Celular , Antígenos HLA-C/genética , Antígenos HLA-C/inmunología , Humanos , Células Asesinas Naturales/citología , Fosforilación/genética , Fosforilación/inmunología , Proteína Tirosina Fosfatasa no Receptora Tipo 6/genética , Proteína Tirosina Fosfatasa no Receptora Tipo 6/inmunología , Receptores KIR2DL1/genética , Receptores KIR2DL1/inmunología , Transducción de Señal/genética , Transducción de Señal/inmunología
13.
Proc Natl Acad Sci U S A ; 110(51): 20831-6, 2013 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-24302765

RESUMEN

Dysferlinopathies, most commonly limb girdle muscular dystrophy 2B and Miyoshi myopathy, are degenerative myopathies caused by mutations in the DYSF gene encoding the protein dysferlin. Studies of dysferlin have focused on its role in the repair of the sarcolemma of skeletal muscle, but dysferlin's association with calcium (Ca(2+)) signaling proteins in the transverse (t-) tubules suggests additional roles. Here, we reveal that dysferlin is enriched in the t-tubule membrane of mature skeletal muscle fibers. Following experimental membrane stress in vitro, dysferlin-deficient muscle fibers undergo extensive functional and structural disruption of the t-tubules that is ameliorated by reducing external [Ca(2+)] or blocking L-type Ca(2+) channels with diltiazem. Furthermore, we demonstrate that diltiazem treatment of dysferlin-deficient mice significantly reduces eccentric contraction-induced t-tubule damage, inflammation, and necrosis, which resulted in a concomitant increase in postinjury functional recovery. Our discovery of dysferlin as a t-tubule protein that stabilizes stress-induced Ca(2+) signaling offers a therapeutic avenue for limb girdle muscular dystrophy 2B and Miyoshi myopathy patients.


Asunto(s)
Señalización del Calcio , Membrana Celular/metabolismo , Proteínas de la Membrana/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Distrofia Muscular de Cinturas/metabolismo , Estrés Fisiológico , Animales , Antihipertensivos/farmacología , Canales de Calcio Tipo L/genética , Canales de Calcio Tipo L/metabolismo , Membrana Celular/patología , Diltiazem/farmacología , Disferlina , Proteínas de la Membrana/genética , Ratones , Ratones Mutantes , Contracción Muscular/efectos de los fármacos , Contracción Muscular/genética , Fibras Musculares Esqueléticas/patología , Distrofia Muscular de Cinturas/genética , Distrofia Muscular de Cinturas/patología , Necrosis/genética , Necrosis/metabolismo , Necrosis/patología
15.
Biophys J ; 108(9): 2158-70, 2015 May 05.
Artículo en Inglés | MEDLINE | ID: mdl-25954874

RESUMEN

Between 8 to 14 calcium-calmodulin (Ca(2+)/CaM) dependent protein kinase-II (CaMKII) subunits form a complex that modulates synaptic activity. In living cells, the autoinhibited holoenzyme is organized as catalytic-domain pairs distributed around a central oligomerization-domain core. The functional significance of catalytic-domain pairing is not known. In a provocative model, catalytic-domain pairing was hypothesized to prevent ATP access to catalytic sites. If correct, kinase-activity would require catalytic-domain pair separation. Simultaneous homo-FRET and fluorescence correlation spectroscopy was used to detect structural changes correlated with kinase activation under physiological conditions. Saturating Ca(2+)/CaM triggered Threonine-286 autophosphorylation and a large increase in CaMKII holoenzyme hydrodynamic volume without any appreciable change in catalytic-domain pair proximity or subunit stoichiometry. An alternative hypothesis is that two appropriately positioned Threonine-286 interaction-sites (T-sites), each located on the catalytic-domain of a pair, are required for holoenzyme interactions with target proteins. Addition of a T-site ligand, in the presence of Ca(2+)/CaM, elicited a large decrease in catalytic-domain homo-FRET, which was blocked by mutating the T-site (I205K). Apparently catalytic-domain pairing is altered to allow T-site interactions.


Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/química , Dominio Catalítico , Secuencia de Aminoácidos , Calcio/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Células HEK293 , Holoenzimas/química , Holoenzimas/metabolismo , Humanos , Datos de Secuencia Molecular , Unión Proteica , Treonina/química , Treonina/metabolismo
16.
Methods ; 66(2): 131-8, 2014 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-23811334

RESUMEN

Förster resonance energy transfer (FRET) describes a physical phenomenon widely applied in biomedical research to estimate separations between biological molecules. Routinely, genetic engineering is used to incorporate spectral variants of the green fluorescent protein (GFPs), into cellular expressed proteins. The transfer efficiency or rate of energy transfer between donor and acceptor FPs is then assayed. As appreciable FRET occurs only when donors and acceptors are in close proximity (1-10nm), the presence of FRET may indicate that the engineered proteins associate as interacting species. For a homogeneous population of FRET pairs the separations between FRET donors and acceptors can be estimated from a measured FRET efficiency if it is assumed that donors and acceptors are randomly oriented and rotate extensively during their excited state (dynamic regime). Unlike typical organic fluorophores, the rotational correlation-times of FPs are typically much longer than their fluorescence lifetime; accordingly FPs are virtually static during their excited state. Thus, estimating separations between FP FRET pairs is problematic. To overcome this obstacle, we present here a simple method for estimating separations between FPs using the experimentally measured average FRET efficiency. This approach assumes that donor and acceptor fluorophores are randomly oriented, but do not rotate during their excited state (static regime). This approach utilizes a Monte-Carlo simulation generated look-up table that allows one to estimate the separation, normalized to the Förster distance, from the average FRET efficiency. Assuming a dynamic regime overestimates the separation significantly (by 10% near 0.5 and 30% near 0.75 efficiencies) compared to assuming a static regime, which is more appropriate for estimates of separations between FPs.


Asunto(s)
Transferencia Resonante de Energía de Fluorescencia/métodos , Algoritmos , Simulación por Computador , Colorantes Fluorescentes/química , Microscopía Fluorescente/métodos , Método de Montecarlo
17.
BMC Musculoskelet Disord ; 16: 332, 2015 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-26537894

RESUMEN

BACKGROUND: Patients with back pain radiating to the leg(s) report worse symptoms and poorer recovery than those with back pain alone. Robust evidence regarding their epidemiological profile is lacking from primary care, the setting where most of these patients will present and be managed. Our objective was to describe the characteristics of patients with back and leg pain, including sciatica, seeking treatment in primary care. METHODS: Adults visiting their general practitioner with back and leg pain, of any duration and severity, were invited to participate. Participants completed questionnaires, underwent clinical assessments and received MRI scans. Characteristics of the sample are described, and differences between patients diagnosed with referred leg pain and those with sciatica are analysed. RESULTS: Six hundred nine patients participated; 62.6 % were female, mean (SD) age 50.2 (13.9). 67.5 % reported pain below the knee, 60.7 % were in paid employment with 39.7 % reporting time off work. Mean disability (RMDQ) was 12.7 (5.7) and mean pain intensity was 5.6 (2.2) and 5.2 (2.4) for back and leg respectively. Mean sciatica bothersomeness index (SBI) was 14.9 (5.1). Three quarters (74.2 %) were clinically diagnosed as having sciatica. In the sciatica group, leg pain intensity, neuropathic pain, pain below the knee, leg pain worse than back pain, SBI and positive MRI findings were significantly higher as compared to patients with referred leg pain. CONCLUSIONS: This primary care cohort reported high levels of disability and pain. This is the first epidemiological study of unselected primary care patients seeking healthcare for back and leg pain. Follow-up of this cohort will investigate the prognostic value of their baseline characteristics. This new information will contribute to our understanding of the characteristics and clinical features of this population, and will underpin future research aimed at defining prognostic subgroups to enable better targeting of health care provision.


Asunto(s)
Dolor de la Región Lumbar/epidemiología , Atención Primaria de Salud/estadística & datos numéricos , Ciática/epidemiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Prospectivos , Reino Unido/epidemiología , Adulto Joven
18.
Commun Biol ; 7(1): 766, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38918547

RESUMEN

The calcium calmodulin protein kinase II (CaMKII) is a multi-subunit ring assembly with a central hub formed by the association domains. There is evidence for hub polymorphism between and within CaMKII isoforms, but the link between polymorphism and subunit exchange has not been resolved. Here, we present near-atomic resolution cryogenic electron microscopy (cryo-EM) structures revealing that hubs from the α and ß isoforms, either standalone or within an ß holoenzyme, coexist as 12 and 14 subunit assemblies. Single-molecule fluorescence microscopy of Venus-tagged holoenzymes detects intermediate assemblies and progressive dimer loss due to intrinsic holoenzyme lability, and holoenzyme disassembly into dimers upon mutagenesis of a conserved inter-domain contact. Molecular dynamics (MD) simulations show the flexibility of 4-subunit precursors, extracted in-silico from the ß hub polymorphs, encompassing the curvature of both polymorphs. The MD explains how an open hub structure also obtained from the ß holoenzyme sample could be created by dimer loss and analysis of its cryo-EM dataset reveals how the gap could open further. An assembly model, considering dimer concentration dependence and strain differences between polymorphs, proposes a mechanism for intrinsic hub lability to fine-tune the stoichiometry of αß heterooligomers for their dynamic localization within synapses in neurons.


Asunto(s)
Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina , Microscopía por Crioelectrón , Simulación de Dinámica Molecular , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/química , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/genética , Humanos , Holoenzimas/química , Holoenzimas/metabolismo , Holoenzimas/genética , Multimerización de Proteína , Animales
19.
Chiropr Man Therap ; 32(1): 16, 2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38745213

RESUMEN

BACKGROUND: Research waste is defined as research outcomes with no or minimal societal benefits. It is a widespread problem in the healthcare field. Four primary sources of research waste have been defined: (1) irrelevant or low priority research questions, (2) poor design or methodology, (3) lack of publication, and (4) biased or inadequate reporting. This commentary, which was developed by a multidisciplinary group of researchers with spinal manipulative therapy (SMT) research expertise, discusses waste in SMT research and provides suggestions to improve future research. MAIN TEXT: This commentary examines common sources of waste in SMT research, focusing on design and methodological issues, by drawing on prior research and examples from clinical and mechanistic SMT studies. Clinical research is dominated by small studies and studies with a high risk of bias. This problem is compounded by systematic reviews that pool heterogenous data from varying populations, settings, and application of SMT. Research focusing on the mechanisms of SMT often fails to address the clinical relevance of mechanisms, relies on very short follow-up periods, and has inadequate control for contextual factors. CONCLUSIONS: This call to action is directed to researchers in the field of SMT. It is critical that the SMT research community act to improve the way research is designed, conducted, and disseminated. We present specific key action points and resources, which should enhance the quality and usefulness of future SMT research.


Asunto(s)
Manipulación Espinal , Humanos , Manipulación Espinal/métodos , Proyectos de Investigación , Investigación Biomédica
20.
Chiropr Man Therap ; 32(1): 17, 2024 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-38773515

RESUMEN

BACKGROUND: Musculoskeletal conditions are the leading contributor to global disability and health burden. Manual therapy (MT) interventions are commonly recommended in clinical guidelines and used in the management of musculoskeletal conditions. Traditional systems of manual therapy (TMT), including physiotherapy, osteopathy, chiropractic, and soft tissue therapy have been built on principles such as clinician-centred assessment, patho-anatomical reasoning, and technique specificity. These historical principles are not supported by current evidence. However, data from clinical trials support the clinical and cost effectiveness of manual therapy as an intervention for musculoskeletal conditions, when used as part of a package of care. PURPOSE: The purpose of this paper is to propose a modern evidence-guided framework for the teaching and practice of MT which avoids reference to and reliance on the outdated principles of TMT. This framework is based on three fundamental humanistic dimensions common in all aspects of healthcare: safety, comfort, and efficiency. These practical elements are contextualised by positive communication, a collaborative context, and person-centred care. The framework facilitates best-practice, reasoning, and communication and is exemplified here with two case studies. METHODS: A literature review stimulated by a new method of teaching manual therapy, reflecting contemporary evidence, being trialled at a United Kingdom education institute. A group of experienced, internationally-based academics, clinicians, and researchers from across the spectrum of manual therapy was convened. Perspectives were elicited through reviews of contemporary literature and discussions in an iterative process. Public presentations were made to multidisciplinary groups and feedback was incorporated. Consensus was achieved through repeated discussion of relevant elements. CONCLUSIONS: Manual therapy interventions should include both passive and active, person-empowering interventions such as exercise, education, and lifestyle adaptations. These should be delivered in a contextualised healing environment with a well-developed person-practitioner therapeutic alliance. Teaching manual therapy should follow this model.


Asunto(s)
Manipulaciones Musculoesqueléticas , Humanos , Manipulaciones Musculoesqueléticas/educación , Manipulaciones Musculoesqueléticas/métodos , Enfermedades Musculoesqueléticas/terapia
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