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Miralles-Iborra A, Elvira JLL, Urban T, Calado A, Del Coso J, Moreno-Pérez V. Agreement between isokinetic eccentric hamstring strength, Nordic hamstring strength and Nordic break-point angle in a sample of trained and healthy individuals. Eur J Sport Sci 2023; 23:155-164. [PMID: 34865597 DOI: 10.1080/17461391.2021.2014984] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Different eccentric strength assessments are used to identifying the risk of hamstring injury in athletes. However, there is scarce information to determine the association between Nordic-based measurements and the gold standard measurement of eccentric hamstring strength in an isokinetic dynamometer. To investigate the relationship of different measures of eccentric hamstring strength (break-point angle and eccentric strength during Nordic exercise) with eccentric hamstring peak torque measured with an isokinetic dynamometer. Forty-six participants volunteered to participate in this study. Eccentric peak force in the Smart-Nordic System and break-point angle measured as trunk lowering at >20°/s and >150°/s2 during the Nordic exercise via high-frequency video-analysis were compared to eccentric hamstring peak torque in an isokinetic dynamometer set to produce knee extension at 30°/s. There was a moderate association between peak eccentric strength with the Smart-Nordic and isokinetic eccentric hamstring peak torque (r = -0.65, p < 0.001, 95%CI = [-0.76-(-0.50)]). The association between Nordic break-point angle measured at 20°/s (r = 0.49, p < 0.001, 95%CI = [0.30-0.64]) and at 150°/s2 (r = 0.52, p < 0.001, 95%CI = [0.33-0.66]) presented statistically significant but lower associations with isokinetic eccentric hamstring peak torque. All Nordic-based measurements presented acceptable associations with the gold standard isokinetic eccentric hamstring peak torque. However, peak eccentric force measured on the Smart-Nordic device had a better agreement with eccentric peak torque measured with an isokinetic dynamometer than the video-based measurements.Highlights Peak eccentric force measured on the isometric strain-gauges device had a better agreement with eccentric hamstring peak torque measured with an isokinetic dynamometer than the break-point angle.The Nordic-based measurements are an alternative cost-effective method to assess eccentric muscle strength and weakness when the access to isokinetic dynamometry is not feasible.Caution should be taken with certain variables such as participants body mass, hip position and movement speed when interpreting the results of Nordic-based measurements.
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Affiliation(s)
- A Miralles-Iborra
- Sports Research Centre (Department of Sport Sciences), Miguel Hernandez University of Elche, Alicante, Spain
| | - J L L Elvira
- Sports Research Centre (Department of Sport Sciences), Miguel Hernandez University of Elche, Alicante, Spain
| | - T Urban
- Sports Research Centre (Department of Sport Sciences), Miguel Hernandez University of Elche, Alicante, Spain
| | - A Calado
- Rio Ave Rendimento, Rio Ave FC, Vila do Conde, Portugal
| | - J Del Coso
- Centre for Sport Studies, Rey Juan Carlos University, Madrid, Spain
| | - V Moreno-Pérez
- Sports Research Centre (Department of Sport Sciences), Miguel Hernandez University of Elche, Alicante, Spain.,Center for Translational Research in Physiotherapy, Department of Pathology and Surgery, Miguel Hernandez University of Elche, San Joan, Spain
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Moreno-Pérez V, Travassos B, Calado A, Gonzalo-Skok O, Del Coso J, Mendez-Villanueva A. Adductor squeeze test and groin injuries in elite football players: A prospective study. Phys Ther Sport 2019; 37:54-59. [PMID: 30856592 DOI: 10.1016/j.ptsp.2019.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 01/17/2023]
Abstract
OBJECTIVE To examining the relationship between hip adductor strength and groin injury incidence during the competitive season of professional football teams. DESIGN Prospective Cohort study. SETTING Controlled laboratory environment. PARTICIPANTS Seventy-one players volunteered to participate. MAIN OUTCOME MEASURES In the pre-season, maximal hip adductor strength was measured by means of the isometric adductor squeeze test. Hip adductor strength, normalized by body mass, was compared between players who suffered a groin injury (n = 18) vs uninjured players (n = 53). Risk ratios (RR) were used to evaluate the likelihood of players to suffer this type of injury. RESULTS Most of the reported groin injuries occurred during competitive matches (5.5 per 1000 match hours). Maximal isometric hip adductor strength was lower in the groin-injured group compared with their uninjured counterparts (429.8 ± 100 vs 564 ± 58.7 N, d = -1.58 and 5.40 ± 1.27 vs 7.71 ± 0.89 N/kg, d = -1.88, respectively). Results revealed that values of maximal isometric adductor strength lower than 465.33 N increased the probability to suffer a groin injury by 72%. Furthermore, values of force relative to body mass lower than 6.971 N/kg increased the probability to suffer a groin injury by 83%. CONCLUSION The assessment of Hip adductor strength, in addition to other measurements, might help practitioners to determine the probability of suffering an overuse groin injuries in elite football players.
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Affiliation(s)
- V Moreno-Pérez
- Sports Research Centre, Miguel Hernandez University of Elche, Avda. de La Universidad s/n, 03202, Elche, Alicante, Spain.
| | - B Travassos
- Departamento de Ciências do Desporto, Universidade da Beira Interior, Convento de Sto. António. 6201-001, Covilhã, Portugal.
| | - A Calado
- Rio Ave Rendimento, Rio Ave FC, Rua Sancho I, Estadio do Rio Ave, 4489-876, Vila do Conde, Portugal.
| | - O Gonzalo-Skok
- Faculty of Health Sciences, University of San Jorge of Zaragoza, Villanueva de Gállego, 50830, Zaragoza, Spain.
| | - J Del Coso
- Exercise Physiology Laboratory, Camilo José Cela University, Sport Sciences Institute Castillo de Alarcón, 49, Villafranca del Castillo, None, 28692, Spain.
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Vitorino de Almeida V, Silva-Herdade A, Calado A, Rosário H, Saldanha C. Fibrinogen modulates leukocyte recruitment in vivo during the acute inflammatory response. Clin Hemorheol Microcirc 2015; 59:97-106. [DOI: 10.3233/ch-121660] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- V. Vitorino de Almeida
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - A. Silva-Herdade
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - A. Calado
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - H.S. Rosário
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - C. Saldanha
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
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Calado A, Duarte A A, Pego J. Parotid Adenocarcinoma with Osteolytic Activity in a Cat. J Comp Pathol 2014. [DOI: 10.1016/j.jcpa.2013.11.156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Calado A, Silva T, Santos C, Figueira A, Prada J, Canavarro I. Diffuse Iris Melanoma with Atypical Metastatic Behaviour in a Cat. J Comp Pathol 2014. [DOI: 10.1016/j.jcpa.2013.11.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Dias S, Sequeira J, Morgado J, Jacinto J, Calado A, Pena J. Unilateral asterixis following thalamic stroke. J Neurol Sci 2013. [DOI: 10.1016/j.jns.2013.07.1049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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de Almeida VV, Calado A, Silva-Herdade AS, Rosário HS, Saldanha C. An in vitro study on the modulation of the neutrophil adhesive behavior by soluble fibrinogen. Clin Hemorheol Microcirc 2012; 56:47-56. [PMID: 23271201 DOI: 10.3233/ch-121662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fibrinogen constitutes an important plasma glycoprotein involved in hemostasis and in inflammation. Previously, we have shown that at physiological concentrations, soluble fibrinogen is able to modulate the pattern of neutrophil activation. This led us to propose that under these conditions, fibrinogen could as well interfere with the adhesive behaviour of circulating neutrophils which is of utmost importance in their recruitment to the vascular wall during inflammatory processes. To address our working hypothesis, in vitro adhesion assays were here performed in a flow chamber by using primary cultures of human umbilical vein endothelial cells (HUVEC) and neutrophils isolated from peripheral venous blood of healthy human donors. In the presence of a physiological concentration of soluble fibrinogen (300 mg/dL), we observed that despite the number of neutrophils rolling on an activated endothelium was not affected, their rolling velocity was increased in comparison to that of non-activated neutrophils. Consequently as expected, the number of fibrinogen-treated neutrophils adhering to activated HUVEC monolayers was significantly diminished. Overall, we have here demonstrated that at least in vitro, soluble fibrinogen under physiological concentrations is able to modulate the interaction of neutrophils with the vascular endothelium. In vivo studies will enable us in the future to study the physiological relevance of these findings and further to understand the mechanisms underlying this function.
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Affiliation(s)
- V Vitorino de Almeida
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - A Calado
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - A S Silva-Herdade
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - H S Rosário
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
| | - C Saldanha
- Unidade de Biologia Microvascular e Inflamação, Instituto de Medicina Molecular, Instituto de Bioquímica, Faculdade de Medicina, Universidade de Lisboa, Portugal
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de Oliveira P, Gomes A, Pacheco T, Vitorino de Almeida V, Saldanha C, Calado A. Cell-specific regulation of acetylcholinesterase expression under inflammatory conditions. Clin Hemorheol Microcirc 2012; 51:129-37. [DOI: 10.3233/ch-2011-1520] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- P. de Oliveira
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - A.Q. Gomes
- Escola Superior de Tecnologia da Saúde de Lisboa, Lisboa, Portugal
| | - T.R. Pacheco
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - V. Vitorino de Almeida
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - C. Saldanha
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - A. Calado
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
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De Oliveira S, Vitorino de Almeida V, Calado A, Rosário HS, Saldanha C. Integrin-associated protein (CD47) is a putative mediator for soluble fibrinogen interaction with human red blood cells membrane. Biochim Biophys Acta 2011; 1818:481-90. [PMID: 22079249 DOI: 10.1016/j.bbamem.2011.10.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 10/12/2011] [Accepted: 10/27/2011] [Indexed: 10/15/2022]
Abstract
Fibrinogen is a multifunctional plasma protein that plays a crucial role in several biological processes. Elevated fibrinogen induces erythrocyte hyperaggregation, suggesting an interaction between this protein and red blood cells (RBCs). Several studies support the concept that fibrinogen interacts with RBC membrane and this binding, due to specific and non-specific mechanisms, may be a trigger to RBC hyperaggregation in inflammation. The main goals of our work were to prove that human RBCs are able to specifically bind soluble fibrinogen, and identify membrane molecular targets that could be involved in this process. RBCs were first isolated from blood of healthy individuals and then separated in different age fractions by discontinuous Percoll gradients. After isolation RBC samples were incubated with human soluble fibrinogen and/or with a blocking antibody against CD47 followed by fluorescence confocal microscopy, flow cytometry acquisitions and zeta potential measurements. Our data show that soluble fibrinogen interacts with the human RBC membrane in an age-dependent manner, with younger RBCs interacting more with soluble fibrinogen than the older cells. Importantly, this interaction is abrogated in the presence of a specific antibody against CD47. Our results support a specific and age-dependent interaction of soluble fibrinogen with human RBC membrane; additionally we present CD47 as a putative mediator in this process. This interaction may contribute to RBC hyperaggregation in inflammation.
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Bettencourt A, Florindo HF, Ferreira IFS, Matos A, Monteiro J, Neves C, Lopes P, Calado A, Castro M, Almeida AJ. Incorporation of tocopherol acetate-containing particles in acrylic bone cement. J Microencapsul 2010; 27:533-41. [PMID: 20459296 DOI: 10.3109/02652048.2010.484106] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Acrylic bone cement (BC) is used in orthopaedic surgery to anchor cemented prostheses to bone. Association of antioxidant molecules to BC may suppress reactive species injury which contributes to implant failure. Tocopherol acetate (ATA)-loaded polymethylmethacrylate (PMMA) particles (ATA(PMMA)) were prepared by single emulsion solvent evaporation technique and were incorporated into BC. An encapsulation efficiency of 84% (w/w) was obtained and drug release studies showed distinct ATA release profiles and mechanisms before and after particle incorporation into BC. Experimental data, analysed using first-order, Higuchi and Korsmeyer-Peppas models revealed that ATA was released from particles by a Fickian diffusion mechanism while a non-Fickian transport was observed upon particle incorporation in BC. There were no changes in the mechanical properties of BC specimens containing ATA(PMMA) particles, in contrast to what was observed when ATA was loaded directly into BC. Overall, ATA(PMMA) particles are potential carriers for the incorporation of an antioxidant drug into BC.
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Affiliation(s)
- A Bettencourt
- Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003 Lisbon, Portugal.
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Vila-Real H, Alfaia A, Calado A, Ribeiro M. Beta-glucosidase inactivation from naringinase, using a combined thermal and Ph approach. N Biotechnol 2009. [DOI: 10.1016/j.nbt.2009.06.484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bettencourt A, Calado A, Amaral J, Alfaia A, Vale FM, Monteiro J, Montemor MF, Ferreira MGS, Castro M. Surface studies on acrylic bone cement. Int J Pharm 2004; 278:181-6. [PMID: 15158960 DOI: 10.1016/j.ijpharm.2004.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2003] [Revised: 03/12/2004] [Accepted: 03/12/2004] [Indexed: 10/26/2022]
Abstract
Poly(methyl methacrylate) (PMMA) is used to fill the gap between the prosthesis and the surrounding bone in cemented arthroplasties. Biocompatibility problems related to bone cement application limit the clinical success of these cemented arthroplasties. Being the cement surface in close connection with the living bone, it is reasonable to assume that surface properties such as, surface composition and surface energy, will play a role in the biomaterial performance. X-ray photoelectron spectroscopy (XPS) analysis and surface energy studies were carried out during 4 months, in order to assess a possible correlation between aging time and surface changes. The aging of PMMA, in a biological model fluid, strongly influences the composition and wettability of the cement surface. These changes may be explained through the hydrolysis of PMMA ester groups and the subsequent hydrogen bonding. Although our study does not exactly reproduce the in vivo environment surrounding a prosthesis, it suggests that the changes in the composition and wettability of the surface may modulate the host response towards the implant, thus contributing to its loosening.
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Affiliation(s)
- A Bettencourt
- Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisbon 1649-003, Portugal.
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Abstract
Prosthesis loosening is a major problem associated with the use of poly(methyl methacrylate) (PMMA) bone cement that may be related to a peri-implant vacuolisation commonly observed at bone-cement interface. Methyl methacrylate (MMA) monomer may be one of the cement components partly responsible for the mentioned vacuolisation due to a cytotoxic effect associated to this compound. Alcoholism has been related to bone necrosis in predisposed individuals. Furthermore, ethanol has been shown to clean material with adherent cement debris during cleaning procedure in laboratory. Consequently, we have decided to study whether ethanol will also be related to an increased liberation of MMA from the polymer matrix. 'In vitro' release studies using PMMA plates were conducted to access the role of ethanol on the liberation of the monomer. Contact angle measurements and surface tension estimation were also carried out in order to find a possible effect of ethanol on surface cement properties. Results suggest that ethanol, even in small quantities, enhances the leaching of the monomer from the polymer matrix, but does not considerably change the wettability properties of the cement surface.
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Affiliation(s)
- A Bettencourt
- Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisbon, Portugal.
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Bettencourt A, Calado A, Amaral J, Vale FM, Rico JM, Monteiro J, Castro M. The influence of vacuum mixing on methylmethacrylate liberation from acrylic cement powder. Int J Pharm 2001; 219:89-93. [PMID: 11337169 DOI: 10.1016/s0378-5173(01)00630-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Polymethylmethacrylate (PMMA) bone cement is a biomaterial used to anchor prostheses during joint replacement surgery. Residual methylmethacrylate monomer (MMA) may be related with the cytotoxic effect of PMMA. The aim of the present paper was to investigate the effect of two different cement mixing methods: hand stirring at atmospheric pressure and under partial vacuum (0.330 and 0.154 bar) on residual monomer liberation in phosphate buffer saline solution from acrylic cement powder. Residual MMA content was determined by high-performance liquid chromatography. Mathematical models were applied to experimental dissolution data revealing that monomer release was significantly reduced in bone cement powder obtained at 0.154 bar vacuum pressure compared to the other mixing conditions. The kinetic models applied are consistent with a simple diffusion mechanism of the monomer from the polymer matrix.
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Affiliation(s)
- A Bettencourt
- Faculdade de Farmácia, Universidade de Lisboa, Av. das Forcas Armadas, 1600-083, Lisbon, Portugal.
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Vautier D, Chesné P, Cunha C, Calado A, Renard JP, Carmo-Fonseca M. Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos. J Cell Sci 2001; 114:1521-31. [PMID: 11282028 DOI: 10.1242/jcs.114.8.1521] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A unique feature of certain members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family of proteins is that they shuttle continuously between nucleus and cytoplasm and their accumulation in the nucleus is transcription-dependent. An extensively characterised protein of this group is hnRNP A1. To date, most studies addressing the transcription-dependent transport of hnRNP A1 have been performed on cultured cell lines treated with transcription inhibitors. Here we have analysed the nucleocytoplasmic distribution of hnRNP A1 in early mouse embryos, where the haploid pronuclei remain transcriptionally inactive for a period of several hours. Consistent with its small molecular size (36 kDa), the hnRNP A1 protein diffuses passively through the nuclear pores and equilibrates between the nucleus and the cytoplasm of transcriptionally inactive embryos. In contrast, following transcriptional activation the A1 protein becomes accumulated in the nucleus. This accumulation of the A1 protein in the nucleus is blocked by the lectin wheat germ agglutinin (WGA), which binds to nuclear pore proteins and prevents translocation of receptor-cargo complexes through the pores. This indicates that a carrier-mediated transport pathway is required for the concentration of A1 in transcriptionally active nuclei. To further analyse how transcription is coupled to nucleocytoplasmic transport, we transplanted transcriptionally inactive pronuclei into the cytoplasm of transcriptionally active embryos. The results show that the presence of newly synthesised RNAs in the cytoplasm is not sufficient to induce the accumulation of hnRNP A1 in the nucleus. Rather, the appearance of nascent transcripts in the nucleus appears to be the crucial event. Since hnRNP A1 is a shuttling protein, an increase in its steady state nuclear concentration could be the result of either faster nuclear import or slower export to the cytoplasm. We propose that binding of A1 to nascent transcripts retards its export to the cytoplasm and therefore contributes to its concentration in the nucleus.
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Affiliation(s)
- D Vautier
- Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Portugal
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Kutay U, Hartmann E, Treichel N, Calado A, Carmo-Fonseca M, Prehn S, Kraft R, Gorlich D, Bischoff FR. Identification of two novel RanGTP-binding proteins belonging to the importin beta superfamily. J Biol Chem 2000; 275:40163-8. [PMID: 11024021 DOI: 10.1074/jbc.m006242200] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleo-cytoplasmic transport comprises a large number of distinct pathways, many of which are defined by members of the importin beta superfamily of nuclear transport receptors. These transport receptors all directly interact with RanGTP to modulate the compartment-specific binding of their transport substrates. To identify new members of the importin beta family, we used affinity chromatography on immobilized RanGTP and isolated Ran-binding protein (RanBP) 16 from HeLa cell extracts. RanBP16 and its close human homologue, RanBP17, are distant members of the importin beta family. Like the other members of the transport receptor superfamily, RanBP16 interacts with the nuclear pore complex and is able to enter the nucleus independent of energy and additional nuclear transport receptors.
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Affiliation(s)
- U Kutay
- Swiss Federal Institute of Technology Zürich, Institute of Biochemistry, 8092 Zürich, Switzerland.
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Calado A, Tomé FM, Brais B, Rouleau GA, Kühn U, Wahle E, Carmo-Fonseca M. Nuclear inclusions in oculopharyngeal muscular dystrophy consist of poly(A) binding protein 2 aggregates which sequester poly(A) RNA. Hum Mol Genet 2000; 9:2321-8. [PMID: 11001936 DOI: 10.1093/oxfordjournals.hmg.a018924] [Citation(s) in RCA: 186] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset disease characterized by progressive eyelid drooping, swallowing difficulties and proximal limb weakness. The autosomal dominant form of the disease is caused by short (GCG)(8-13) expansions in the PABP2 gene. This gene encodes the poly(A) binding protein 2 (PABP2), an abundant nuclear protein that binds with high affinity to nascent poly(A) tails, stimulating their extension and controlling their length. In this work we report that PABP2 is detected in filamentous nuclear inclusions, which are the pathological hallmark of OPMD. Using both immunoelectron microscopy and fluorescence confocal microscopy, the OPMD-specific nuclear inclusions appeared decorated by anti-PABP2 antibodies. In addition, the inclusions were labeled with antibodies directed against ubiquitin and the subunits of the proteasome and contained a form of PABP2 that was more resistant to salt extraction than the protein dispersed in the nucleoplasm. This suggests that the polyalanine expansions in PABP2 induce a misfolding and aggregation of the protein into insoluble inclusions, similarly to events in neurodegenerative diseases caused by CAG/polyglutamine expansions. No significant differences were observed in the steady-state poly(A) tail length in OPMD and normal myoblasts. However, the nuclear inclusions were shown to sequester poly(A) RNA. This raises the possibility that in OPMD the polyalanine expansions in the PABP2 protein may interfere with the cellular traffic of poly(A) RNA.
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Affiliation(s)
- A Calado
- Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Avenida Prof. Egas Moniz, 1649-028 Lisbon, Portugal
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Calado A, Carmo-Fonseca M. Localization of poly(A)-binding protein 2 (PABP2) in nuclear speckles is independent of import into the nucleus and requires binding to poly(A) RNA. J Cell Sci 2000; 113 ( Pt 12):2309-18. [PMID: 10825302 DOI: 10.1242/jcs.113.12.2309] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nuclei of mammalian cells contain domains, termed nuclear speckles, which are enriched in splicing factors and poly(A) RNA. Although nuclear speckles are thought to represent reservoirs from which splicing factors are recruited to sites of transcription and splicing, the presence of poly(A) RNA in these structures remains enigmatic. An additional component of the speckles is poly(A) binding protein 2 (PABP2), a protein that binds with high affinity to nascent poly(A) tails, stimulating their extension and controlling their length. In this work we investigated whether PABP2 contributes to the targeting of poly(A) RNA to the speckles. The results show that localization of PABP2 in speckles is independent of import of the protein into the nucleus. Inhibition of transcription or poly(A) synthesis at the end of mitosis does not affect nuclear import of PABP2 but prevents its localization to speckles. Furthermore, PABP2 mutants with decreased ability to bind to poly(A) fail to localize to speckles. Taken together the results show that PABP2 localizes to the nuclear speckles as a consequence of its binding to poly(A) RNA, contrasting to splicing factors which assemble into speckles in the absence of newly synthesized transcripts.
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Affiliation(s)
- A Calado
- Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Portugal
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Bettencourt A, Calado A, Amaral J, Vale FM, Rico JM, Monteiro J, Lopes A, Pereira L, Castro M. In vitro release studies of methylmethacrylate liberation from acrylic cement powder. Int J Pharm 2000; 197:161-8. [PMID: 10704803 DOI: 10.1016/s0378-5173(99)00468-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bone cement or polymethylmethacrylate (PMMA) is commonly used for anchoring cemented prosthesis to the bone. Cytotoxic effect of culture media exposed to PMMA powder may be related with long term problems associated with acrylic cement application, being the monomer (methylmethacrylate) one of the cement's component partly responsible for the cytotoxic effect. The present work reports the studies of monomer release from acrylic bone cement powder under different experimental conditions: setting time of PMMA (in solution and air) and different culture media composition. High-performance liquid chromatography was used for the determination of residual monomer. Mathematical models were applied to experimental dissolution data revealing that monomer release is lightly affected by the studied variables. The monomer release seems to be a surface phenomena, suggesting that the possible actions of monomer will mainly be due to the initial loss of non polymerized monomer rather than to further depolymerization of the already polymerized cement.
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Affiliation(s)
- A Bettencourt
- Faculdade de Farmácia da Universidade de Lisboa, Av. das Forças Armadas, 1600-083, Lisbon, Portugal.
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Abstract
Within the nucleus, protein-encoding genes are transcribed into messenger RNA by RNA polymerase II. Messenger RNAs migrate to the cytoplasm, but before reaching their final destination the primary transcripts must undergo a series of modifications that include 5'-capping, splicing, and 3'-cleavage/polyadenylation. Errors in these processing events can originate aberrant products that, if translated, would produce abnormal proteins. Therefore, it is not surprising that eukaryotes have evolved a surveillance mechanism that recognizes and rapidly degrades aberrant mRNAs. Recent experiments provide exciting insights into how proper mRNAs are distinguished and selected for export. Transcription by RNA polymerase II is directly coupled to pre-mRNA processing, and the mechanism that targets the processing machinery to the polymerase complex suggests a model for co-transcriptional proofreading. Furthermore, there is evidence that at least some mRNAs move randomly throughout the nucleus, presumably by free diffusion. In this light, retention of aberrant mRNAs by the transcription/processing machinery is crucial to prevent their diffusion to the nuclear pores and eventual translocation to the cytoplasm.
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Affiliation(s)
- M Carmo-Fonseca
- Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Portugal
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Abstract
Poly(A)-binding protein II (PABP2) is an abundant nuclear protein that binds with high affinity to nascent poly(A) tails, stimulating their extension and controlling their length. In the cytoplasm, a distinct protein (PABP1) binds to poly(A) tails and participates in mRNA translation and stability. How cytoplasmic PABP1 substitutes for nuclear PABP2 is still unknown. Here we report that PABP2 shuttles back and forth between nucleus and cytoplasm by a carrier-mediated mechanism. A potential novel type of nuclear localization signal exists at the C-terminus of the protein, a domain that is highly enriched in methylated arginines. PABP2 binds directly to transportin in a RanGTP-sensitive manner, suggesting an involvement of this transport receptor in mediating import of the protein into the nucleus. Although PABP2 is small enough to diffuse passively through the nuclear pores, protein fusion experiments reveal the existence of a facilitated export pathway. Accordingly, no transport of PABP2 to the cytoplasm occurs at 4 degrees C. In contrast, export of PABP2 continues in the absence of transcription, indicating that transport to the cytoplasm is independent of mRNA traffic. Thus, rather than leaving the nucleus as a passive passenger of mRNAs, the data suggest that PABP2 interacts with the nuclear export machinery and may therefore contribute to mRNA transport.
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Affiliation(s)
- A Calado
- Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Lisboa, Portugal
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