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1.
Br J Sports Med ; 54(16): 949-959, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32475821

RESUMO

The highly infectious and pathogenic novel coronavirus (CoV), severe acute respiratory syndrome (SARS)-CoV-2, has emerged causing a global pandemic. Although COVID-19 predominantly affects the respiratory system, evidence indicates a multisystem disease which is frequently severe and often results in death. Long-term sequelae of COVID-19 are unknown, but evidence from previous CoV outbreaks demonstrates impaired pulmonary and physical function, reduced quality of life and emotional distress. Many COVID-19 survivors who require critical care may develop psychological, physical and cognitive impairments. There is a clear need for guidance on the rehabilitation of COVID-19 survivors. This consensus statement was developed by an expert panel in the fields of rehabilitation, sport and exercise medicine (SEM), rheumatology, psychiatry, general practice, psychology and specialist pain, working at the Defence Medical Rehabilitation Centre, Stanford Hall, UK. Seven teams appraised evidence for the following domains relating to COVID-19 rehabilitation requirements: pulmonary, cardiac, SEM, psychological, musculoskeletal, neurorehabilitation and general medical. A chair combined recommendations generated within teams. A writing committee prepared the consensus statement in accordance with the appraisal of guidelines research and evaluation criteria, grading all recommendations with levels of evidence. Authors scored their level of agreement with each recommendation on a scale of 0-10. Substantial agreement (range 7.5-10) was reached for 36 recommendations following a chaired agreement meeting that was attended by all authors. This consensus statement provides an overarching framework assimilating evidence and likely requirements of multidisciplinary rehabilitation post COVID-19 illness, for a target population of active individuals, including military personnel and athletes.


Assuntos
Infecções por Coronavirus/reabilitação , Pneumonia Viral/reabilitação , Reabilitação/normas , Betacoronavirus , COVID-19 , Humanos , Medicina , Pandemias , SARS-CoV-2 , Reino Unido
2.
BMC Musculoskelet Disord ; 18(1): 204, 2017 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-28532478

RESUMO

BACKGROUND: Chronic tendinopathy is a significant problem particularly in active populations limiting sporting and occupational performance. The prevalence of patellar tendinopathy in some sports is near 50% and the incidence of lower limb tendinopathy is 1.4% p.a. in the UK Military. Management includes isometric, eccentric, heavy slow resistance exercises and extracorporeal shockwave therapy (ESWT). Often these treatments are inadequate yet there is no good evidence for injection therapies and success rates from surgery can be as low as 50%. High Volume Image Guided Injection (HVIGI) proposes to strip away the neovascularity and disrupt the nerve ingrowth seen in chronic cases and has shown promising results in case series. This study aims to investigate the efficacy of HVIGI in a randomised controlled trial (RCT). METHODS: RCT comparing 40ml HVIGI, with or without corticosteroid, with a 3ml local anaesthetic sham-control injection. Ninety-six participants will be recruited. INCLUSION CRITERIA: male, 18-55 years old, chronic Achilles or patellar tendinopathy of at least 6 months, failed conservative management including ESWT, and Ultrasound (US) evidence of neovascularisation, tendon thickening and echogenic changes. Outcome measures will be recorded at baseline, 6 weeks, 3, 6 and 12 months. Primary outcome measures include The Victoria Institute of Sport Assessments for Achilles and patellar tendinopathy (VISA-A and VISA-P) and VAS pain. Secondary outcome measures include Modified Ohberg score, maximum tendon diameter and assessment of hypoechoic appearance on US, and Functional Activity Assessment. DISCUSSION: Despite previous interventional trials and reviews there is still insufficient evidence to guide injectable therapy for chronic tendinopathy that has failed conservative treatment. The scant evidence available suggests HVIGI has the greatest potential however there is no level one RCT evidence to support this. Investigating the efficacy of HVIGI against control in a RCT and separating the effect of HVIGI and corticosteroid will add high level evidence to the management of chronic tendinopathy resistant to conservative treatment. TRIAL REGISTRATION: EudraCT: 2015-003587-36 3 Dec 2015.


Assuntos
Tendão do Calcâneo/diagnóstico por imagem , Corticosteroides/administração & dosagem , Patela/diagnóstico por imagem , Tendinopatia/diagnóstico por imagem , Tendinopatia/tratamento farmacológico , Ultrassonografia de Intervenção/métodos , Tendão do Calcâneo/efeitos dos fármacos , Adolescente , Adulto , Anestésicos Locais/administração & dosagem , Método Duplo-Cego , Humanos , Injeções , Masculino , Pessoa de Meia-Idade , Patela/efeitos dos fármacos , Adulto Jovem
3.
BMC Musculoskelet Disord ; 17(1): 459, 2016 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-27821103

RESUMO

BACKGROUND: Non-arthritic hip disorders are defined as abnormalities of the articulating surfaces of the acetabulum and femur before the onset of osteoarthritis, including intra-articular structures such as the acetabular labrum and chondral surfaces. Abnormal femoroacetabular morphology is commonly seen in young men who constitute much of the UK military population. Residential multidisciplinary team (MDT) rehabilitation for patients with musculoskeletal injuries has a long tradition in the UK military, however, there are no studies presenting empirical data on the efficacy of a residential MDT approach compared with individualised conventional outpatient treatment. With no available data, the sustainability of this care pathway has been questioned. The purpose of this randomised controlled trial is to compare the effects of a residential multidisciplinary intervention, to usual outpatient care, on the clinical outcomes of young active adults undergoing treatment for non-arthritic intra-articular hip pain. METHODS/DESIGN: The trial will be conducted at the Defence Medical Rehabilitation Centre, Headley Court, UK. One hundred military male participants with clinical indicators of non-arthritic intra-articular hip pain will be randomly allocated to either: (1) 7-day residential multidisciplinary team intervention, n = 50; (2) 6-week physiotherapist-led outpatient intervention (conventional care), n = 50. Measurements will be taken at baseline, post-treatment (1-week MDT group; 6-weeks physiotherapy group), and 12-weeks. The primary outcome measures are the function in daily living sub-scale of the Copenhagen Hip and Groin Outcome Score (HAGOS), the physical function subscale of the Non-arthritic Hip Score (NAHS), and VAS pain scale. Secondary outcomes include objective measures of physical capacity and general health. An intention-to-treat analysis will be performed using linear and mixed models. DISCUSSION: This study will be the first to assess the efficacy of intensive MDT rehabilitation, versus conventional outpatient care, for the management of non-arthritic hip pain. The results from this study will add to the evidence-base and inform clinical practice for the management of intra-articular non-arthritic hip pain and femoroacetabular impingement in young active adults. TRIAL REGISTRATION: ISRCTN Reference: ISRCTN 59255714 dated 11-Nov-2015.


Assuntos
Assistência Ambulatorial/métodos , Artralgia/terapia , Terapia por Exercício/métodos , Impacto Femoroacetabular/complicações , Articulação do Quadril/patologia , Modalidades de Fisioterapia , Adulto , Artralgia/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Militares , Medição da Dor , Equipe de Assistência ao Paciente , Medicina de Precisão/métodos , Centros de Reabilitação , Instituições Residenciais , Resultado do Tratamento , Reino Unido , Adulto Jovem
4.
EMBO J ; 27(1): 62-75, 2008 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-18079697

RESUMO

T lymphocytes use LFA-1 to migrate into lymph nodes and inflammatory sites. To investigate the mechanisms regulating this migration, we utilize mAbs selective for conformational epitopes as probes for active LFA-1. Expression of the KIM127 epitope, but not the 24 epitope, defines the extended conformation of LFA-1, which has intermediate affinity for ligand ICAM-1. A key finding is that KIM127-positive LFA-1 forms new adhesions at the T lymphocyte leading edge. This LFA-1 links to the cytoskeleton through alpha-actinin-1 and disruption at the level of integrin or actin results in loss of cell spreading and migratory speed due to a failure of attachment at the leading edge. The KIM127 pattern contrasts with high-affinity LFA-1 that expresses both 24 and KIM127 epitopes, is restricted to the mid-cell focal zone and controls ICAM-1 attachment. Identification of distinctive roles for intermediate- and high-affinity LFA-1 in T lymphocyte migration provides a biological function for two active conformations of this integrin for the first time.


Assuntos
Actinina/metabolismo , Movimento Celular/imunologia , Antígeno-1 Associado à Função Linfocitária/metabolismo , Linfócitos T/metabolismo , Sequência de Aminoácidos , Anticorpos Bloqueadores/metabolismo , Anticorpos Monoclonais/metabolismo , Linhagem Celular , Linhagem Celular Transformada , Linhagem Celular Tumoral , Epitopos de Linfócito T/imunologia , Humanos , Antígeno-1 Associado à Função Linfocitária/química , Antígeno-1 Associado à Função Linfocitária/imunologia , Antígeno-1 Associado à Função Linfocitária/fisiologia , Dados de Sequência Molecular , Ligação Proteica/imunologia , Conformação Proteica , Isoformas de Proteínas/química , Isoformas de Proteínas/imunologia , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/fisiologia , Linfócitos T/imunologia
5.
Orthop J Sports Med ; 10(4): 23259671221088326, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35425844

RESUMO

Background: Chronic Achilles and patellar tendinopathy are a significant burden in physically active populations. High-volume image-guided injection (HVIGI) proposes to strip away associated neovascularity, disrupt painful nerve ingrowth, and facilitate rehabilitation. Purpose: To investigate the efficacy of HVIGI with and without steroid relative to placebo. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 62 participants were recruited between May 25, 2016, and March 5, 2020. Participants were men aged 18 to 55 years with Achilles or patellar tendinopathy of at least 6-month chronicity that had not improved with nonoperative management (including physical therapy and shockwave therapy), with ultrasound evidence of neovascularization, tendon thickening, and echogenic changes. They were assigned to the following groups: control (3 mL of subcutaneous 0.5% bupivacaine), HVIGI (10 mL of 0.5% bupivacaine and 30 mL of normal saline, ultrasound-guided between tendon and underlying fat pad), or HVIGI with steroid (HVIGIwSteroid; 0.25 mL of 100 mg/mL hydrocortisone). Clinicians and assessors were blinded. All participants were supervised through a pain-guided progressive loading program for 6 months postinjection. The main outcome measures were the Victoria Institute of Sport Assessments (VISA) for Achilles and patellar tendinopathy and the visual analog scale (VAS) for pain at 6 months postinjection. Results: The VISA score improved by a mean of 22.8 points (95% CI, 10.4-35.3 points; effect size [ES], 1.51) in the control group (n = 21), 18.6 points (95% CI, 9.1-28.0 points; ES, 1.31) in the HVIGI group (n = 21), and 18.5 points (95% CI, 3.4-33.6 points; ES, 0.88) in the HVIGIwSteroid group (n = 20). VAS pain improved by a mean of 15 points (interquartile range [IQR], -38.75, 8 points; ES, 0.39) in controls, 13 points (IQR,-34.0, 3.75 points; ES, 0.47) in the HVIGI group, and 27 points (IQR,-38.0, -1.0 points; ES, 0.54) in the HVIGIwSteroid group. The main effects were significant for time (P < .001) but not group (P ≥ .48), with no group × time interaction (P = .71). One participant was lost to follow-up from each group, multiple imputation was used for missing data points. No adverse events occurred. Conclusion: Study findings did not demonstrate superiority of HVIGI over control injection. Registration: EU Clinical Trials Register (EudraCT: 2015-003587-36).

6.
J Public Health (Oxf) ; 33(2): 256-61, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20581127

RESUMO

BACKGROUND: Rugby union is the most popular worldwide collision sport, yet concerns have been raised regarding the safety of the sport due to the physical, high impact nature and an increasing number of injuries. METHODS: A prospective, cohort study of the incidence, pattern and severity of injuries in rugby players in six Scottish schools during the second half of the 2008-09 season. Definition of injury and severity of injury were taken from International Rugby Board (IRB) consensus guidelines. Injury report forms and exposure data for match play were completed by a nominated staff member. RESULTS: Four hundred and seventy consent forms with survey information were returned. Of 37 rugby injuries in the study, 11 occurred during training. Head and face were the most injured body part and sprain/ligament injury the most common injury. Twenty injuries required attendance at Accident & Emergency with one admission. The tackle was the commonest phase of play causing injury. In the 193 matches played, the injury incidence during the match play was 10.8 injuries per 1000 player hours. CONCLUSIONS: This study confirms the feasibility of collecting relevant injury data in schools rugby in Scotland. The findings are consistent with other studies with respect to incidence and profile of injuries sustained.


Assuntos
Traumatismos em Atletas/epidemiologia , Futebol Americano/lesões , Adolescente , Criança , Feminino , Humanos , Escala de Gravidade do Ferimento , Masculino , Estudos Prospectivos , Roupa de Proteção , Instituições Acadêmicas , Escócia/epidemiologia
7.
Curr Biol ; 16(14): 1447-52, 2006 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-16860745

RESUMO

During asymmetric cytoplasmic mRNA transport, cis-acting localization signals are widely assumed to tether a specific subset of transcripts to motor complexes that have intrinsic directionality. Here we provide evidence that mRNA transcripts control their sorting by regulating the relative activities of opposing motors on microtubules. We show in Drosophila embryos that all mRNAs undergo bidirectional transport on microtubules and that cis-acting elements produce a range of polarized transcript distributions by regulating the frequency, velocity, and duration of minus-end-directed runs. Increased minus-end motility is dependent on the dosage of RNA elements and the proteins Egalitarian (Egl) and Bicaudal-D (BicD). We show that these proteins, together with the dynein motor, are recruited differentially to different RNA signals. Cytoplasmic transfer experiments reveal that, once assembled, cargo/motor complexes are insensitive to reduced cytoplasmic levels of transport proteins. Thus, the concentration of these proteins is only critical at the onset of transport. This work suggests that the architecture of RNA elements, through Egl and BicD, regulates directional transport by controlling the relative numbers of opposite polarity motors assembled. Our data raise the possibility that recruitment of different numbers of motors and regulatory proteins is a general strategy by which microtubule-based cargoes control their sorting.


Assuntos
Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Dineínas/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , RNA Mensageiro/metabolismo , Animais , Drosophila/embriologia , Drosophila/genética , Proteínas de Drosophila/fisiologia , Dineínas/fisiologia , Embrião não Mamífero/metabolismo , Embrião não Mamífero/ultraestrutura , Microtúbulos/metabolismo , Modelos Biológicos , RNA Mensageiro/análise , RNA Mensageiro/fisiologia
8.
Br J Sports Med ; 41(6): 392-7, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17261562

RESUMO

OBJECTIVE: To determine if ice-water immersion after eccentric quadriceps exercise minimises the symptoms of delayed-onset muscle soreness (DOMS). DESIGN: A prospective randomised double-blind controlled trial was undertaken. 40 untrained volunteers performed an eccentric loading protocol with their non-dominant leg. INTERVENTIONS: Participants were randomised to three 1-min immersions in either ice water (5+/-1 degrees C) or tepid water (24 degrees C). MAIN OUTCOME MEASURES: Pain and tenderness (visual analogue scale), swelling (thigh circumference), function (one-legged hop for distance), maximal isometric strength and serum creatine kinase (CK) recorded at baseline, 24, 48 and 72 h after exercise. Changes in outcome measures over time were compared to determine the effect of group allocation using independent t tests or Mann-Whitney U tests. RESULTS: No significant differences were observed between groups with regard to changes in most pain parameters, tenderness, isometric strength, swelling, hop-for-distance or serum CK over time. There was a significant difference in pain on sit-to-stand at 24 h, with the intervention group demonstrating a greater increase in pain than the control group (median change 8.0 vs 2.0 mm, respectively, p = 0.009). CONCLUSIONS: The protocol of ice-water immersion used in this study was ineffectual in minimising markers of DOMS in untrained individuals. This study challenges the wide use of this intervention as a recovery strategy by athletes.


Assuntos
Crioterapia/métodos , Exercício Físico , Hidroterapia/métodos , Músculo Esquelético/fisiopatologia , Manejo da Dor , Adulto , Biomarcadores/sangue , Protocolos Clínicos , Creatina Quinase/sangue , Método Duplo-Cego , Feminino , Humanos , Gelo , Perna (Membro) , Masculino , Dor/diagnóstico , Medição da Dor , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento
9.
Nat Commun ; 7: 11245, 2016 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-27071537

RESUMO

RAS signalling through phosphoinositide 3-kinase (PI3-Kinase) has been shown to have an essential role in tumour initiation and maintenance. RAS also regulates cell motility and tumour invasiveness, but the role of direct RAS binding to PI3-Kinase in this remains uncertain. Here, we provide evidence that disruption of RAS interaction with PI3-Kinase p110α decreases cell motility and prevents activation of Rac GTPase. Analysis of gene expression in cells lacking RAS interaction with p110α reveals increased levels of the extracellular matrix glycoprotein Reelin and activation of its downstream pathway resulting in upregulation of E-cadherin expression. Induction of the Reelin/E-cadherin axis is also observed in Kras mutant lung tumours that are regressing due to blockade of RAS interaction with PI3-Kinase. Furthermore, loss of Reelin correlates with decreased survival of lung and breast cancer patients. Reelin thus plays a role in restraining RAS and PI3-kinase promotion of cell motility and potentially tumour metastasis.


Assuntos
Moléculas de Adesão Celular Neuronais/metabolismo , Movimento Celular , Proteínas da Matriz Extracelular/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Serina Endopeptidases/metabolismo , Transdução de Sinais , Proteínas ras/metabolismo , Animais , Caderinas/metabolismo , Polaridade Celular , Ativação Enzimática , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Camundongos , Ligação Proteica , Proteína Reelina , Regulação para Cima , Proteínas rac1 de Ligação ao GTP/metabolismo
10.
BMJ Open Sport Exerc Med ; 2(1): e000107, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27900174

RESUMO

BACKGROUND: There are no studies describing the clinical outcomes of a residential, multidisciplinary team (MDT) rehabilitation intervention for patients with prearthritic hip pain. The aim of this cohort study was to describe the functional and physical outcomes of multidisciplinary residential rehabilitation for UK military personnel with prearthritic hip pain. METHODS: Participants (N=40) with a mean age of 33 years referred to a specialist residential rehabilitation centre completed a comprehensive multidisciplinary residential intervention. The main outcome measures were mean pain, physical function (modified shuttle test (MST) and Y-balance test), hip range of motion (HROM) and a patient-reported outcome measure (The Copenhagen Hip and Groin Outcome Score, HAGOS). All scores for symptomatic hips were taken at baseline and post-treatment. RESULTS: There were improvements in the Y-balance test and HROM following rehabilitation. There were significant improvements in mean difference (T1-to-T2) for Y-balance scores (15.8 cm, 95% CI 10.7 to 20.9, p<0.001), HROM (6.5° increase in hip flexion, 95% CI 4.6 to 9.4, p<0.001) and hip internal rotation (4.6°, 95% CI 2.7 to 6.6, p<0.001). Scores for HAGOS, pain, MST and functional activity assessment showed no improvement. CONCLUSIONS: Among UK military personnel with prearthritic hip pain, MDT residential rehabilitation resulted in improvements in a functional Y-balance test, hip flexion and internal rotation. The study suggests short-term benefits across some outcomes for the current UK military approach to MDT residential rehabilitation.

12.
Mol Cancer Ther ; 11(9): 1884-93, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22752425

RESUMO

Activating mutations in Kras are the most frequent mutations in human cancer. They define a subset of patients who do not respond to current therapies and for whom prognosis is poor. Oncogenic Kras has been shown to deregulate numerous signaling pathways of which the most intensively studied are the Ras/extracellular signal-regulated kinase cascade and the phosphoinositide 3-kinase (PI3K)/Akt cascade. However, to date, there are no effective targeted therapies in the clinic against Kras-mutant cancers. Here, we report that the ß-galactoside-binding protein (ßGBP) cytokine, a physiologic inhibitor of class I PI3Ks, is a potent activator of apoptosis in Kras-mutant colorectal cancer cells, even when coharboring mutant-activated PIK3CA. Our study unveils an elective route to intrinsic and extrinsic apoptosis, which involves the cytoskeleton. Early events are inhibition of PI3K activity and Rac-independent actin rearrangement assignable to phosphoinositide changes at the plasma membrane. Cyclin E deregulation, arrest of DNA synthesis, and checkpoint kinase 2 activation underscore events critical to the activation of an intrinsic apoptotic program. Clustering of CD95/Fas death receptors underscore events critical to the activation of extrinsic apoptosis. In nude mice, we present the first evidence that xenograft tumor development is strongly inhibited by Hu-r-ßGBP. Taken together, our results open a new therapeutic opportunity to a subset of patients refractive to current treatments. This first demonstration of therapeutic efficacy against Kras-mutant colon cancer suggests that Hu-r-ßGBP may also be therapeutically effective against other cancers harboring activating Ras mutations as well as PIK3CA mutations.


Assuntos
Actinas/metabolismo , Antineoplásicos/farmacologia , Neoplasias do Colo/tratamento farmacológico , Galectinas/farmacologia , Inibidores de Fosfoinositídeo-3 Quinase , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Animais , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Proliferação de Células , Forma Celular , Quinase do Ponto de Checagem 2 , Ciclina E/metabolismo , Replicação do DNA , Resistencia a Medicamentos Antineoplásicos , Ativação Enzimática , Feminino , Galectinas/uso terapêutico , Humanos , Potencial da Membrana Mitocondrial , Camundongos , Camundongos Nus , Mutação de Sentido Incorreto , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas p21(ras) , Ensaios Antitumorais Modelo de Xenoenxerto , Receptor fas/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo
14.
Biochemistry ; 46(45): 12930-44, 2007 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-17935306

RESUMO

Nonviral gene delivery vectors now show good therapeutic potential: however, detailed characterization of the composition and macromolecular organization of such particles remains a challenge. This paper describes experiments to elucidate the structure of a ternary, targeted, lipopolyplex synthetic vector, the LID complex. This consists of a lipid component, Lipofectin (L) (1:1 DOTMA:DOPE), plasmid DNA (D), and a dual-function, cationic peptide component (I) containing DNA condensation and integrin-targeting sequences. Fluorophore-labeled lipid, peptide, and DNA components were used to formulate the vector, and the stoichiometry of the particles was established by fluorescence correlation spectroscopy (FCS). The size of the complex was measured by FCS, and the sizes of LID, L, LD, and ID complexes were measured by dynamic light scattering (DLS). Fluorescence quenching experiments and freeze-fracture electron microscopy were then used to demonstrate the arrangement of the lipid, peptide, and DNA components within the complex. These experiments showed that the cationic portion of the peptide, I, interacts with the plasmid DNA, resulting in a tightly condensed DNA-peptide inner core; this is surrounded by a disordered lipid layer, from which the integrin-targeting sequence of the peptide partially protrudes.


Assuntos
Vetores Genéticos , Integrinas , Fenômenos Biofísicos , Biofísica , DNA/química , Difusão , Técnica de Fratura por Congelamento , Luz , Lipossomos/síntese química , Microscopia Eletrônica , Fosfatidiletanolaminas/química , Compostos de Amônio Quaternário/química , Espalhamento de Radiação , Espectrometria de Fluorescência
15.
J Cell Sci ; 119(Pt 10): 2084-94, 2006 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-16687737

RESUMO

The inositol lipid phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2] is involved in a myriad of cellular processes, including the regulation of exocytosis and endocytosis. In this paper, we address the role of PtdIns(4,5)P2 in compound exocytosis from rat peritoneal mast cells. This process involves granule-plasma membrane fusion as well as homotypic granule membrane fusion and occurs without any immediate compensatory endocytosis. Using a novel quantitative immunofluorescence technique, we report that plasma membrane PtdIns(4,5)P2 becomes transiently depleted upon activation of exocytosis, and is not detected on the membranes of fusing granules. Depletion is caused by phospholipase C activity, and is mandatory for exocytosis. Although phospholipase C is required for Ca2+ release from internal stores, the majority of the requirement for PtdIns(4,5)P2 hydrolysis occurs downstream of Ca2+ signalling - as shown in permeabilised cells, where the inositol (1,4,5)-trisphosphate-Ca2+ pathway is bypassed. Neither generation of the PtdIns(4,5)P2 metabolite, diacylglycerol (DAG) or simple removal and/or sequestration of PtdIns(4,5)P2 are sufficient for exocytosis to occur. However, treatment of permeabilised cells with DAG induces a small potentiation of exocytosis, indicating that it may be required. We propose that a cycle of PtdIns(4,5)P2 synthesis and breakdown is crucial for exocytosis to occur in mast cells, and may have a more general role in all professional secretory cells.


Assuntos
Mastócitos/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Animais , Membrana Celular/enzimologia , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular/fisiologia , Ativação Enzimática , Exocitose/fisiologia , Imunofluorescência , Masculino , Mastócitos/enzimologia , Microscopia Confocal , Cavidade Peritoneal/citologia , Fosfatidilinositol 4,5-Difosfato , Ratos , Ratos Sprague-Dawley , Fosfolipases Tipo C/metabolismo
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