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1.
Sci Eng Ethics ; 29(4): 23, 2023 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-37347323

RESUMO

There is growing need for hybrid curricula that integrate constructivist methods from Science and Technology Studies (STS) into both engineering and policy courses at the undergraduate and graduate levels. However, institutional and disciplinary barriers have made implementing such curricula difficult at many institutions. While several programs have recently been launched that mix technical training with consideration of "societal" or "ethical issues," these programs often lack a constructivist element, leaving newly-minted practitioners entering practical fields ill-equipped to unpack the politics of knowledge and technology or engage with skeptical publics. This paper presents a novel format for designing interdisciplinary coursework that combines conceptual content from STS with training in engineering and policy. Courses following this format would ideally be team taught by instructors with advanced training in diverse fields, and hence co-learning between instructors and disciplines is a key element of the format. Several instruments for facilitating both student and instructor collaborative learning are introduced. The format is also designed for versatility: in addition to being adaptable to both technical and policy training environments, topics are modularized around a conceptual core so that issues ranging from biotech to nuclear security can be incorporated to fit programmatic needs and resources.


Assuntos
Currículo , Engenharia , Humanos , Tecnologia , Educação de Pós-Graduação , Política Pública
2.
Malar J ; 21(1): 152, 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35614489

RESUMO

Building on an exercise that identified potential harms from simulated investigational releases of a population suppression gene drive for malaria vector control, a series of online workshops identified nine recommendations to advance future environmental risk assessment of gene drive applications.


Assuntos
Anopheles , Tecnologia de Impulso Genético , Malária , Animais , Anopheles/genética , Malária/prevenção & controle , Controle de Mosquitos , Mosquitos Vetores/genética , Medição de Risco
3.
J Tissue Viability ; 31(1): 73-83, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34238649

RESUMO

Pressure ulcers (PUs) are a major public health challenge, having a significant impact on healthcare service and patient quality of life. Computational biomechanical modelling has enhanced PU research by facilitating the investigation of pressure responses in subcutaneous tissue and skeletal muscle. Extensive work has been undertaken on PUs on patients in the seated posture, but research into heel ulcers has been relatively neglected. The aim of this review was to address the key challenges that exist in developing an effective FE foot model for PU prevention and the confusion surrounding the wide range of outputs reported. Nine FE foot studies investigating heel ulcers in bedrest were identified and reviewed. Six studies modelled the posterior part of the heel, two included the calf and foot, and one modelled the whole body. Due to the complexity of the foot anatomy, all studies involved simplification or assumptions regarding parts of the foot structure, boundary conditions and material parameters. Simulations aimed to understand better the stresses and strains exhibited in the heel soft tissues of the healthy foot. The biomechanical properties of soft tissue derived from experimental measurements are critical for developing a realistic model and consequently guiding clinical decisions. Yet, little to no validation was reported in each of the studies. If FE models are to address future research questions and clinical applications, then sound verification and validation of these models is required to ensure accurate conclusions and prediction of patient outcomes. Recommendations and considerations for future FE studies are therefore proposed.


Assuntos
Úlcera por Pressão , Repouso em Cama , Fenômenos Biomecânicos , Análise de Elementos Finitos , Humanos , Úlcera por Pressão/prevenção & controle , Qualidade de Vida
4.
Curr Issues Mol Biol ; 43(3): 1794-1804, 2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34889904

RESUMO

Thyroid stimulating antibodies (TSAB) cause Graves' disease and contribute to Graves' Orbitopathy (GO) pathogenesis. We hypothesise that the presence of TSH binding proteins (truncated TSHR variants (TSHRv)) and/or nonclassical ligands such as thyrostimulin (α2ß5) might provide a mechanism to protect against or exacerbate GO. We analysed primary human orbital preadipocyte-fibroblasts (OF) from GO patients and people free of GO (non-GO). Transcript (QPCR) and protein (western blot) expression levels of TSHRv were measured through an adipogenesis differentiation process. Cyclic-AMP production by TSHR activation was studied using luciferase-reporter and RIA assays. After differentiation, TSHRv levels in OF from GO were significantly higher than non-GO (p = 0.039), and confirmed in ex vivo analysis of orbital adipose samples. TSHRv western blot revealed a positive signal at 46 kDa in cell lysates and culture media (CM) from non-GO and GO-OF. Cyclic-AMP decreased from basal levels when OF were stimulated with TSH or Monoclonal TSAB (M22) before differentiation protocol, but increased in differentiated cells, and was inversely correlated with the TSHRv:TSHR ratio (Spearman correlation: TSH r = -0.55, p = 0.23, M22 r = 0.87, p = 0.03). In the bioassay, TSH/M22 induced luciferase-light was lower in CM from differentiated GO-OF than non-GO, suggesting that secreted TSHRv had neutralised their effects. α2 transcripts were present but reduced during adipogenesis (p < 0.005) with no difference observed between non-GO and GO. ß5 transcripts were at the limit of detection. Our work demonstrated that TSHRv transcripts are expressed as protein, are more abundant in GO than non-GO OF and have the capacity to regulate signalling via the TSHR.


Assuntos
Proteínas de Transporte/genética , Suscetibilidade a Doenças , Expressão Gênica , Oftalmopatia de Graves/etiologia , Oftalmopatia de Graves/metabolismo , Tireotropina/metabolismo , Autoanticorpos/imunologia , Biomarcadores , Proteínas de Transporte/metabolismo , Variação Genética , Humanos , Receptores da Tireotropina/genética , Receptores da Tireotropina/metabolismo
5.
Hum Mol Genet ; 25(12): 2404-2416, 2016 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-27106103

RESUMO

Mitochondrial dysfunction connects metabolic disturbance with numerous pathologies, but the significance of mitochondrial activity in bone remains unclear. We have, therefore, characterized the skeletal phenotype in the Opa3L122P mouse model for Costeff syndrome, in which a missense mutation of the mitochondrial membrane protein, Opa3, impairs mitochondrial activity resulting in visual and metabolic dysfunction. Although widely expressed in the developing normal mouse head, Opa3 expression was restricted after E14.5 to the retina, brain, teeth and mandibular bone. Opa3 was also expressed in adult tibiae, including at the trabecular surfaces and in cortical osteocytes, epiphyseal chondrocytes, marrow adipocytes and mesenchymal stem cell rosettes. Opa3L122P mice displayed craniofacial abnormalities, including undergrowth of the lower mandible, accompanied in some individuals by cranial asymmetry and incisor malocclusion. Opa3L122P mice showed an 8-fold elevation in tibial marrow adiposity, due largely to increased adipogenesis. In addition, femoral length and cortical diameter and wall thickness were reduced, the weakening of the calcified tissue and the geometric component of strength reducing overall cortical strength in Opa3L122P mice by 65%. In lumbar vertebrae reduced vertebral body area and wall thickness were accompanied by a proportionate reduction in marrow adiposity. Although the total biomechanical strength of lumbar vertebrae was reduced by 35%, the strength of the calcified tissue (σmax) was proportionate to a 38% increase in trabecular number. Thus, mitochondrial function is important for the development and maintenance of skeletal integrity, impaired bone growth and strength, particularly in limb bones, representing a significant new feature of the Costeff syndrome phenotype.


Assuntos
Desenvolvimento Ósseo/genética , Coreia/genética , Erros Inatos do Metabolismo/genética , Mitocôndrias/genética , Atrofia Óptica/genética , Proteínas/genética , Paraplegia Espástica Hereditária/genética , Animais , Encéfalo/crescimento & desenvolvimento , Encéfalo/fisiopatologia , Coreia/fisiopatologia , Modelos Animais de Doenças , Cabeça/crescimento & desenvolvimento , Cabeça/fisiopatologia , Humanos , Mandíbula/crescimento & desenvolvimento , Mandíbula/fisiopatologia , Erros Inatos do Metabolismo/fisiopatologia , Camundongos , Mitocôndrias/patologia , Mutação de Sentido Incorreto , Atrofia Óptica/fisiopatologia , Retina/crescimento & desenvolvimento , Retina/fisiopatologia , Esqueleto/crescimento & desenvolvimento , Esqueleto/fisiopatologia , Paraplegia Espástica Hereditária/fisiopatologia , Dente/crescimento & desenvolvimento , Dente/fisiopatologia
6.
Ophthalmic Plast Reconstr Surg ; 32(2): 145-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26784548

RESUMO

PURPOSE: To present the results of 1-stage surgical advancement flaps for the repair of large full thickness lower eyelid defects. These avoid the disadvantages of the 2-stage Hughes procedure and provide favorable functional and aesthetic outcomes. METHODS: A retrospective case series of 36 lower eyelid repairs performed on 31 patients by a single surgeon in Sydney, Australia is presented. The selection criterion was a horizontal defect size 10 mm or greater that could have "classically" been repaired with a 2-stage Hughes procedure. Three different 1-stage surgical repair techniques were utilized, all incorporating local advancement-type flaps: 1) a lateral-based full thickness advancement flap; 2) a vertical tarsal plate advancement flap combined with a full thickness skin graft; and 3) a vertical skin advancement flap combined with a mucosal graft. The postoperative outcomes evaluated included flap viability, lower eyelid margin position and contour, characteristics of the new eyelid margin and patient satisfaction. RESULTS: Thirty-six lower eyelid repairs were performed in 31 patients. There were no cases of flap ischemia, necrosis, or failure. There was 1 case (3%) of postoperative eyelid retraction, 1 case (3%) of eyelid entropion requiring surgical repair, 1 case (3%) of pyogenic granuloma, 2 cases (6%) of eyelid margin cyst, and 7 cases (19%) of eyelid distichiasis. In 34 cases (94%), the patient was satisfied with the aesthetic result. CONCLUSION: The techniques described provide successful alternatives to the Hughes procedure. They are 1-stage and do not render the patient temporarily monocular, or alter the upper eyelid anatomy or function. All maintained favorable long-term functional and aesthetic outcomes for the reconstructed lower eyelid.


Assuntos
Doenças Palpebrais/cirurgia , Procedimentos Cirúrgicos Oftalmológicos , Procedimentos de Cirurgia Plástica , Retalhos Cirúrgicos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Estudos Retrospectivos
7.
Nature ; 510(7504): 218, 2014 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-24919914
8.
Arthroscopy ; 30(12): 1535-9, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25218007

RESUMO

PURPOSE: To assess the effect of the insertion angle and the angle of applied load on the pullout strength of screw-in suture anchors. METHODS: Screw-in metallic suture anchors were inserted into a 10-lb/cu ft synthetic cancellous bone block at 30°, 45°, 60°, and 90° to the surface. The suture pull angle was then varied in 30° increments between 0° and 180°. Five constructs were tested to failure (anchor pullout) for each combination of angles using a Zwick tensile testing machine (Zwick Roell, Ulm, Germany). RESULTS: There were a total of 25 combinations. The greatest pullout strength was seen with a suture anchor inserted at 90° to the bone block with a pull angle of 90° to the bone (mean, 306 N; standard deviation [SD], 9 N). The weakest pullout strength was seen with a suture anchor inserted at 30° with the angle of pull at 120° (i.e., opposite to the direction of insertion of the anchor) (mean, 97 N; SD, 11 N). A simulated deadman's angle of 45° with an angle of pull of 150° produced a pullout strength of 127 N (SD, 4 N). The pullout strengths for each insertion angle were greatest when the angle of pull was similar to the angle of insertion (P < .0001, repeated-measures analysis of variance). CONCLUSIONS: The angle of applied load to a suture anchor and the insertion angle significantly influence the biomechanical pullout strength of screw-in suture anchors. The insertion angle of the suture anchor should replicate the angle of applied load to ensure the optimum pullout strength. CLINICAL RELEVANCE: The screw-in anchor insertion angle and angle of applied load may have an influence on pullout strength.


Assuntos
Estresse Mecânico , Âncoras de Sutura , Técnicas de Sutura , Análise de Variância , Fenômenos Biomecânicos , Parafusos Ósseos , Humanos , Teste de Materiais , Fenômenos Físicos , Suturas
9.
Colloids Surf A Physicochem Eng Asp ; 460: 83-89, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25431523

RESUMO

Cold atmospheric plasma (CAP) treatment was used on ultra-high molecular weight polyethylene (UHMWPE), a common articulating counter material employed in hip and knee replacements. UHMWPE is a biocompatible polymer with low friction coefficient, yet does not have robust wear characteristics. CAP effectively cross-links the polymer chains of the UHMWPE improving wear performance (Perni et al., Acta Biomater. 8(3) (2012) 1357). In this work, interactions between CAP treated UHMWPE and spherical borosilicate sphere (representing model material for bone) were considered employing AFM technique. Adhesive forces increased, in the presence of PBS, after treatment with helium and helium/oxygen cold gas plasmas. Furthermore, a more hydrophilic surface of UHMWPE was observed after both treatments, determined through a reduction of up to a third in the contact angles of water. On the other hand, the asperity density also decreased by half, yet the asperity height had a three-fold decrease. This work shows that CAP treatment can be a very effective technique at enhancing the adhesion between bone and UHMWPE implant material as aided by the increased adhesion forces. Moreover, the hydrophilicity of the CAP treated UHMWPE can lead to proteins and cells adhesion to the surface of the implant stimulating osseointegration process.

10.
J Vis Commun Med ; 37(1-2): 3-12, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24848573

RESUMO

Investigators assessing the likelihood of physical abuse, must make a decision as to whether the injury seen matches the explanation given. In some instances the pattern of these injuries can give the investigator a possible link to the cause of the injury. Thus, matching an injury pattern to an implement or weapon used has forensic implications. The current method of capturing patterned injuries together with poor scale placement often result in some form of distortion that causes a change to the shape of the patterned injury. The aim of this guideline is to assist individuals dealing with the capture of photographic evidence for the investigation of suspected non-accidental patterned cutaneous injuries (PCI), and to ensure high standards of image quality are met for both evidential records and for forensic analysis. The technical equipment specified within these guidelines are recommended by the authors as a basic requirement for imaging best practice, due to their ability to capture detailed and critical data. For precise pattern matching analysis, it is vital that both the injury and the suspected implement are photographed in accordance with this guidance.


Assuntos
Violência Doméstica , Guias como Assunto , Fotografação/métodos , Fotografação/normas , Pele/lesões , Medicina Legal/métodos , Humanos
11.
PLoS One ; 19(4): e0300346, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38656930

RESUMO

Across the Western United States, human development into the wildland urban interface (WUI) is contributing to increasing wildfire damage. Given that natural disasters often cause greater harm within socio-economically vulnerable groups, research is needed to explore the potential for disproportionate impacts associated with wildfire. Using Zillow Transaction and Assessment Database (ZTRAX), hereafter "Zillow", real estate data, we explored whether lower-priced structures were more likely to be damaged during the most destructive, recent wildfires in Southern California. Within fire perimeters occurring from 2000-2019, we matched property price data to burned and unburned structures. To be included in the final dataset, fire perimeters had to surround at least 25 burned and 25 unburned structures and have been sold at most seven years before the fire; five fires fit these criteria. We found evidence to support our hypothesis that lower-priced properties were more likely to be damaged, however, the likelihood of damage and the influence of property value significantly varied across individual fire perimeters. When considering fires individually, properties within two 2003 fires-the Cedar and Grand Prix-Old Fires-had statistically significantly decreasing burn damage with increasing property value. Occurring in 2007 and later, the other three fires (Witch-Poomacha, Thomas, and Woolsey) showed no significant relationship between price and damage. Consistent with other studies, topographic position, slope, elevation, and vegetation were also significantly associated with the likelihood of a structure being damaged during the wildfire. Driving time to the nearest fire station and previously identified fire hazard were also significant. Our results suggest that further studies on the extent and reason for disproportionate impacts of wildfire are needed. In the meantime, decision makers should consider allocating wildfire risk mitigation resources-such as fire-fighting and wildfire structural preparedness resources-to more socioeconomically vulnerable neighborhoods.


Assuntos
Incêndios Florestais , California , Humanos , Incêndios
12.
J Biomech ; 163: 111913, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38181575

RESUMO

Advancements in systems for prevention and management of pressure ulcers require a more detailed understanding of the complex response of soft tissues to compressive loads. This study aimed at quantifying the progressive deformation of the buttock based on 3D measurements of soft tissue displacements from MR scans of 10 healthy subjects in a semi-recumbent position. Measurements were obtained using digital volume correlation (DVC) and released as a public dataset. A first parametric optimisation of the global registration step aimed at aligning skeletal elements showed acceptable values of Dice coefficient (around 80%). A second parametric optimisation on the deformable registration method showed errors of 0.99mm and 1.78mm against two simulated fields with magnitude 7.30±3.15mm and 19.37±9.58mm, respectively, generated with a finite element model of the buttock under sitting loads. Measurements allowed the quantification of the slide of the gluteus maximus away from the ischial tuberosity (IT, average 13.74 mm) that was only qualitatively identified in the literature, highlighting the importance of the ischial bursa in allowing sliding. Spatial evolution of the maximus shear strain on a path from the IT to the seating interface showed a peak of compression in the fat, close to the interface with the muscle. Obtained peak values were above the proposed damage threshold in the literature. Results in the study showed the complexity of the deformation of the soft tissues in the buttock and the need for further investigations aimed at isolating factors such as tissue geometry, duration and extent of load, sitting posture and tissue properties.


Assuntos
Úlcera por Pressão , Postura Sentada , Humanos , Nádegas , Úlcera por Pressão/prevenção & controle , Postura/fisiologia , Coxa da Perna
13.
Proc Inst Mech Eng H ; 227(2): 120-8, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23513983

RESUMO

The aseptic loosening of total elbow replacements is a serious complication resulting in significant patient morbidity. It is thought to occur secondary to stress shielding of the distal humeral cortex by the stiff stem of the implant. Some total elbow prostheses incorporate an anterior flange intended to improve implant stability and peri-articular load transfer in an attempt to reduce this effect However, few studies have directly assessed the changes in cortical strains following total elbow arthroplasty or the biomechanical advantage of the anterior flange design. A regular and a long flange Coonrad-Morrey total elbow prosthesis were implanted into six Sawbone synthetic humeri. The constructs were subjected to physiological loads in axial compression (500 N), antero-posterior bending (50 N) and antero-posterior compression with condylar supports (300 N). Digital image correlation was used to measure the distal antero-lateral cortical strains and the results compared with those of whole Sawbones that had been tested in the same way. Significant stress shielding was demonstrated over the distal humeral cortex following prosthesis implantation during axial compression. In contrast, cortical strains increased following prosthesis implantation during antero-posterior compression with condylar supports. The increase in cortical strains following total elbow arthroplasty may help to maintain the integrity of the anterior cortex offering additional stability for implants with an anterior flange. These results are important for the development of future total elbow prosthesis designs and indicate that simulating the action of the forearm muscles is essential when evaluating changes in strain about the distal humerus in vitro.


Assuntos
Artroplastia de Substituição do Cotovelo/métodos , Biomimética/métodos , Articulação do Cotovelo/fisiopatologia , Úmero/fisiopatologia , Úmero/cirurgia , Modelos Biológicos , Suporte de Carga , Artroplastia de Substituição do Cotovelo/instrumentação , Força Compressiva , Módulo de Elasticidade , Humanos , Resistência à Tração
14.
BMJ Paediatr Open ; 7(1)2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37491132

RESUMO

Accurate recording of forensically important information on bruises is vital in child protection proceedings (Royal College of Paediatrics and Child Health (RCPCH)). An online survey was distributed to the RCPCH child protection committees to assess compliance with guidance. 56 individuals were contacted by email, 47 (84%) completed the survey. Results showed that the paediatricians always or usually record size (n=41; 87%), site (n=45; 96%), shape (n=32; 68%) and colour (n=36; 77%); n=10; 22% of the paediatricians stated that they 'always' used a ranking system for likelihood of abuse; n=12; 35% of those surveyed 'sometimes' estimated the size of the bruise. Results showed that paediatric bruise reporting is inconsistent and incomplete for some fields compared with national guidance.


Assuntos
Maus-Tratos Infantis , Contusões , Humanos , Criança , Abuso Físico , Contusões/etiologia , Contusões/prevenção & controle , Maus-Tratos Infantis/diagnóstico , Maus-Tratos Infantis/prevenção & controle , Probabilidade , Saúde da Criança
15.
J Mech Behav Biomed Mater ; 142: 105824, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37060717

RESUMO

Bone fracture surface morphology (FSM) can provide valuable information on the cause of failure in forensic and archaeological applications and it depends primarily on three factors, the loading conditions (like strain rate), the ambient conditions (wet or dry bone material) and the quality of bone material itself. The quality of bone material evidently changes in taphonomy as a result of the decomposition process and that in turn is expected to affect FSM. Porcine bones were fractured by a standardised impact during the course of soft tissue decomposition, at 28-day intervals, over 140 days (equivalent to 638 cooling degree days). Measurements of the associated microcracks on the fractured cortical bone surfaces indicated a progressive increase in mean length during decomposition from around 180 µm-375 µm. The morphology of these microcracks also altered, from multiple intersecting microcracks emanating from a central point at 0-28 cumulative cooling degree days, to longer linear cracks appearing to track lamellae as soft tissue decomposition progressed. The implications of these findings are that taphonomic changes of bone may offer the real possibility of distinguishing perimortem and taphonomic damage and also provide a new surrogate parameter for estimation of post-mortem interval (PMI) in forensics.


Assuntos
Antropologia Forense , Fraturas Ósseas , Suínos , Animais , Osso e Ossos , Autopsia , Medicina Legal
16.
Comput Methods Biomech Biomed Engin ; 26(14): 1719-1731, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36420964

RESUMO

Microneedle (MN) array patches present a promising new approach for the minimally invasive delivery of therapeutics and vaccines. However, ensuring reproducible insertion of MNs into the skin is challenging. The spacing and arrangement of MNs in an array are critical determinants of skin penetration and the mechanical integrity of the MNs. In this work, the finite element method was used to model the effect of MN spacing on needle reaction force and skin strain during the indentation phase prior to skin penetration. Spacings smaller than 2-3 mm (depending on variables, e.g., skin stretch) were found to significantly increase these parameters.

17.
J Mech Behav Biomed Mater ; 140: 105704, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36801778

RESUMO

Synthetic models (phantoms) of the brain-skull system are useful tools for the study of surgical events that are otherwise difficult to study directly in humans. To date, very few studies can be found which replicate the full anatomical brain-skull system. Such models are required to study the more global mechanical events that can occur in neurosurgery, such as positional brain shift. Presented in this work is a novel workflow for the fabrication of a biofidelic brain-skull phantom which features a full hydrogel brain with fluid-filled ventricle/fissure spaces, elastomer dural septa and fluid-filled skull. Central to this workflow is the utilization of the frozen intermediate curing state of an established brain tissue surrogate, which allows for a novel moulding and skull installation approach that permits a much fuller recreation of the anatomy. The mechanical realism of the phantom was validated through indentation testing of the phantom's brain and simulation of the supine to prone brain shift event, while the geometric realism was validated through magnetic resonance imaging. The developed phantom captured a novel measurement of the supine to prone brain shift event with a magnitude that accurately reproduces that seen in the literature.


Assuntos
Cabeça , Hidrogéis , Humanos , Crânio , Encéfalo , Imageamento por Ressonância Magnética , Imagens de Fantasmas
18.
Arthritis Rheum ; 63(11): 3417-27, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21769844

RESUMO

OBJECTIVE: We have discovered that a combination of fibroblast growth factor 2 and transforming growth factor ß1 induce profound morphologic changes in immature articular cartilage. The purpose of this study was to test the hypothesis that these changes represent accelerated postnatal maturation. METHODS: Histochemical and biochemical assays were used to confirm the nature of the morphologic changes that accompany growth factor stimulation of immature bovine articular cartilage explants in serum-free culture medium. Growth factor-induced apoptosis, cellular proliferation, and changes in the collagen network were also quantitatively analyzed. RESULTS: Growth factor stimulation resulted in rapid resorption from the basal aspect of immature cartilage explants that was simultaneously opposed by cellular proliferation from the apical aspect driven from a pool of chondroprogenitor cells we have previously described. Maturation-dependent changes in tissue stiffness, collagen crosslinking, and collagen fibril architecture as well as differentiation of the extracellular matrix into distinct pericellular, territorial, and interterritorial domains were all present in growth factor-stimulated cartilage samples and absent in control samples. CONCLUSION: Our data demonstrate that it is possible to significantly enhance the maturation of cartilage tissue using specific growth factor stimulation. This may have applications in transplantation therapy or in the treatment of diseased cartilage, through phenotype modulation of osteoarthritic chondrocytes in order to stimulate growth and maturation of cartilage repair tissue.


Assuntos
Cartilagem Articular/efeitos dos fármacos , Cartilagem Articular/crescimento & desenvolvimento , Condrócitos/efeitos dos fármacos , Fator 2 de Crescimento de Fibroblastos/farmacologia , Fator de Crescimento Transformador beta1/farmacologia , Animais , Apoptose/efeitos dos fármacos , Cartilagem Articular/metabolismo , Bovinos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Condrócitos/metabolismo , Colágeno/metabolismo , Masculino
19.
Knee Surg Sports Traumatol Arthrosc ; 20(2): 262-7, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21779795

RESUMO

PURPOSE: To investigate two different methods of suture fixation and tendon behaviour when using an Endobutton and a tripled tendon. METHODS: Thirty bovine tendons and foam blocks were randomly allocated to three groups: group 1: The tendon was doubled through 40-mm Endobutton; group 2: Tripled tendon--whip-stitched with No. 2 Ultrabraid, passed through an Endobutton and third limb secured to the loop via seven knots; and group 3: Tripled tendon--whip-stitched with No. 2 Fibreloop and fixed as group 2. A tunnel matching the graft diameter was drilled through the block. The graft was passed through the tunnel and fixed with an interference screw. The constructs were cycled at 1 Hz from 10 to 50 N for 10 cycles followed by 50-250 N at 1 Hz for 500 cycles. Load-to-failure test was then carried out at a rate of 20 mm/min. A custom digital image capture technique was used to measure and calculate displacement, strain and stress. Statistical analysis was carried out using Kruskal-Wallis test and paired t test. RESULTS: There was no statistical significant difference between ultimate tensile strength (UTS) (P = 0.35) and yield load (0.41) between the 3 groups. The mean displacement of the third tendon limb in group 2 was 4.8 mm and in group 3, 1.5 mm. Displacement was not statistically significant (P = 0.07). The mean stress in the third limb versus the doubled portion of tendon in group 2 was 0.4 ± 0.02 versus 4.8 ± 0.52 MPa and in group 3, 0.5 ± 0.03 versus 5.2 ± 0.52 MPa. CONCLUSIONS: In this biomechanical study, there was no mechanical difference in the overall properties between a doubled and tripled tendon graft. Significant cyclic elongation occurred in the third limb of the tripled tendon in comparison with the doubled portioned. Further work is needed to determine whether these mechanical findings translate to clinical practice. Caution should be used when tripling hamstring grafts. In particular, tripling small grafts provides no biomechanical advantage immediately and possibly long term, thus potentially increasing the risk of failure.


Assuntos
Reconstrução do Ligamento Cruzado Anterior/métodos , Tendões/transplante , Tenodese/métodos , Animais , Fenômenos Biomecânicos , Bovinos , Técnicas In Vitro , Distribuição Aleatória , Estresse Mecânico , Tendões/fisiologia , Tenodese/instrumentação , Resistência à Tração , Suporte de Carga
20.
Foot Ankle Surg ; 18(3): 195-7, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22857962

RESUMO

BACKGROUND: The aim of this study was to assess bone loss and thickness of the cut with the use of a burr in percutaneous hallux valgus surgery. METHODS: Twelve blocks of saw bone were used. Cuts of same depth were made in each block with two different saw blades and a burr. Each block was assessed for bone loss and thickness of the cut. RESULTS: There was statistically significant (p<0.05) increased bone loss and thickness of the cuts with the use of a burr as compared to use of two different saw blades. The use of a burr resulted in threefold increased loss of bone material and fourfold increase in the thickness of the cut as compare to use of two different saw blades. CONCLUSION: The metatarsal shortening is a risk factor in percutaneous hallux valgus surgery with the use of a burr.


Assuntos
Hallux Valgus/cirurgia , Procedimentos Ortopédicos/efeitos adversos , Reabsorção Óssea/etiologia , Humanos , Procedimentos Ortopédicos/instrumentação , Fatores de Risco
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