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1.
Osteoarthritis Cartilage ; 31(3): 317-339, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36481451

RESUMEN

OBJECTIVE: To investigate the effects and mechanotransduction pathways of therapeutic ultrasound on chondrocytes. METHOD: PubMed, EMBASE and Web of Science databases were searched up to 19th September 2021 to identify in vitro studies exploring ultrasound to stimulate chondrocytes for osteoarthritis (OA) treatment. Study characteristics, ultrasound parameters, in vitro setup, and mechanotransduction pathways were collected. Risk of bias was judged using the Risk of Bias Assessment for Non-randomized Studies (RoBANS) tool. RESULTS: Thirty-one studies were included comprising healthy and OA chondrocytes and explants. Most studies had high risk of performance, detection and pseudoreplication bias due to lack of temperature control, setup calibration, inadequate semi-quantitatively analyzes and independent experiments. Ultrasound was applied to the culture plate via acoustic gel, water bath or culture media. Regardless of the setup used, ultrasound stimulated the cartilage production and suppressed its degradation, although the effect size was nonsignificant. Ultrasound inhibited p38, c-Jun N-terminal kinases (JNK) and factor nuclear kappa B (NFκB) pathways in OA chondrocytes to reduce apoptosis, inflammation and matrix degradation, while triggered phosphoinositide-3-kinase/akt (PI3K/Akt), extracellular signal-regulated kinase (ERK), p38 and JNK pathways in healthy chondrocytes to promote matrix synthesis. CONCLUSION: The included studies suggest that ultrasound application induces therapeutic effects on chondrocytes. However, these results should be interpreted with caution because high risk of performance, detection and pseudoreplication bias were identified. Future studies should explore the application of ultrasound on human OA chondrocytes cultures to potentiate the applicability of ultrasound towards cartilage regeneration of knee with OA.


Asunto(s)
Cartílago Articular , Osteoartritis , Terapia por Ultrasonido , Humanos , Condrocitos/metabolismo , Mecanotransducción Celular , Proteínas Proto-Oncogénicas c-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Cartílago Articular/metabolismo , Osteoartritis/metabolismo
2.
Immunohematology ; 38(4): 123-129, 2022 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-36789463

RESUMEN

Variant RHCE alleles are found mainly in Afro-descendant individuals, as well as in patients with sickle cell disease (SCD). The most common variants are related to the RHCE*ce allele, which can generate partial e and c antigens. Although RHCE variant alleles have been extensively studied, defining their clinical significance is a difficult task. We evaluated the risk of RhCE alloimmunization as a consequence of partial antigens in patients with a positive phenotype transfused with red blood cell (RBC) units with the corresponding antigen. A retrospective study was performed with Brazilian patients, evaluating the number of antigen-positive transfused RBC units (incompatible due to partial antigen) in 27 patients with SCD carrying RHCE variant alleles who did not develop antibodies as well as evaluating the variants present in 12 patients with partial phenotype and correlated antibody (one patient with SCD and 11 patients with other pathologies). Two patients showed variant alleles with molecular changes that had not yet been described. Variant RHCE alleles were identified in a previous study using molecular methods. RHCE*ceVS.01 was the most frequent allele found among the patients without antibodies. Six patients with partial c antigen had a mean of 3.8 c+ RBC units transfused, and 10 patients with partial e antigen were exposed for a mean of 7.2 e+ RBC units. Among the variant alleles found in alloimmunized patients, the most frequent was RHCE*ceAR, which was found in five patients; the antibodies developed were anti-hrS and/or anti-c. Our results showed that RHCE*ceVS.01 is indeed the most frequent variant allele in our cohort of patients with SCD, but the partial antigens that were identified have low risk of alloimmunization. RHCE*ceAR is the most impactful variant in the Brazilian population with high risk of alloimmunization and clinically significant anti-hrS formation.


Asunto(s)
Anemia Hemolítica Autoinmune , Anemia de Células Falciformes , Humanos , Sistema del Grupo Sanguíneo Rh-Hr/genética , Alelos , Brasil , Estudios Retrospectivos , Isoanticuerpos , Anemia de Células Falciformes/genética , Anemia de Células Falciformes/terapia
3.
J Appl Microbiol ; 128(2): 513-517, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31587491

RESUMEN

AIM: To select the best combination of arbuscular mycorrhizal fungi and efficient vermicompost dose in maximizing the production of leaf metabolites in Punica granatum seedlings. METHODS AND RESULTS: The experimental design was in a 3 × 3 factorial arrangement: three inoculation treatments (inoculated with Gigaspora albida, inoculated with Acaulospora longula and control not inoculated) × 3 doses of vermicompost (0, 5 and 7·5%). After 120 days of inoculation, biomolecules, plant growth parameters and mycorrhizal colonization were evaluated. The combination of 7·5% of vermicompost and A. longula was favourable to the accumulation of leaf phenols, with an increase of 116·11% in relation to the non-inoculated control. The total tannins was optimized/enhanced when G. albida and 7·5% of fertilizer were used, registering an increase of 276·71%. CONCLUSIONS: The application of 7·5% of vermicompost associated with A. longula and G. albida is a low cost alternative to increase the levels of bioactive compounds in pomegranate leaves. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first published report of optimization of bioactive compound production in P. granatum by the combined use of mycorrhiza and vermicompost doses.


Asunto(s)
Producción de Cultivos/métodos , Fertilizantes/análisis , Glomeromycota/fisiología , Micorrizas/fisiología , Agricultura Orgánica/métodos , Hojas de la Planta/química , Granada (Fruta)/crecimiento & desarrollo , Producción de Cultivos/economía , Frutas/química , Frutas/crecimiento & desarrollo , Frutas/metabolismo , Agricultura Orgánica/economía , Fenoles/análisis , Fenoles/metabolismo , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Granada (Fruta)/química , Granada (Fruta)/metabolismo , Plantones/química , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Taninos/análisis , Taninos/metabolismo
4.
J Cardiothorac Vasc Anesth ; 34(6): 1622-1635, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32276758

RESUMEN

SEPARATION from cardiopulmonary bypass (CPB) after cardiac surgery is a progressive transition from full mechanical circulatory and respiratory support to spontaneous mechanical activity of the lungs and heart. During the separation phase, measurements of cardiac performance with transesophageal echocardiography (TEE) provide the rationale behind the diagnostic and therapeutic decision-making process. In many cases, it is possible to predict a complex separation from CPB, such as when there is known preoperative left or right ventricular dysfunction, bleeding, hypovolemia, vasoplegia, pulmonary hypertension, or owing to technical complications related to the surgery. Prompt diagnosis and therapeutic decisions regarding mechanical or pharmacologic support have to be made within a few minutes. In fact, a complex separation from CPB if not adequately treated leads to a poor outcome in the vast majority of cases. Unfortunately, no specific criteria defining complex separation from CPB and no management guidelines for these patients currently exist. Taking into account the above considerations, the aim of the present review is to describe the most common scenarios associated with a complex CPB separation and to suggest strategies, pharmacologic agents, and para-corporeal mechanical devices that can be adopted to manage patients with complex separation from CPB. The routine management strategies of complex CPB separation of 17 large cardiac centers from 14 countries in 5 continents will also be described.


Asunto(s)
Procedimientos Quirúrgicos Cardíacos , Cirugía Torácica , Disfunción Ventricular Derecha , Puente Cardiopulmonar/efectos adversos , Ecocardiografía Transesofágica , Humanos
5.
J Med Entomol ; 52(1): 50-5, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26336279

RESUMEN

Paederus beetles are cosmopolitan medically important insects that cause dermatitis linearis to humans. In Brazil, despite the medical importance of these beetles, no studies focusing directly on the abundance and ecological features of harmful species exist. Therefore, this study aims at determining the abundance and the nocturnal hourly dispersal of Paederus species attracted to fluorescent, incandescent, and black light sources in the Brazilian savanna. Paederus species were captured from May to September for three consecutive years, between 2011 and 2013. The specimens were caught hourly, from 1800 to 0600 hours. Paederus beetles were attracted to incandescent, fluorescent, and black light lamps as light sources. A total of 959 individuals of five species were collected. The collected species were Paederus protensus Sharp (59.85%), Paederus columbinus Laporte de Castelnau (29.20%), Paederus mutans Sharp (7.09%), Paederus brasiliensis Erichson (3.34%), and Paederus ferus Erichson (0.52%). The black light was the most attractive source, and the darkest collecting point was the most representative for the number of individuals. The lowest catches were captured at full moon, and the highest catches were between 2200 and 0100 hours. Future investigations are needed to better understand the role of night temperature and soil humidity affecting the seasonal growth of Paederus beetle populations of northeastern Brazil.


Asunto(s)
Escarabajos/fisiología , Animales , Brasil , Femenino , Luz , Masculino , Dinámica Poblacional , Estaciones del Año , Factores de Tiempo
6.
Med Vet Entomol ; 28(2): 228-31, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24382216

RESUMEN

Culicoides biting midges (Diptera: Ceratopogonidae) are of great medical and veterinary importance because the haematophagous females of some species can transmit diseases to humans and animals. In order to determine the presence and seasonal abundance of the bluetongue virus (BTV) vector Culicoides insignis Lutz at domestic animal sheds in northeastern Brazil, insects were collected once a month between January and December 2010. Light traps were set from 18.00 to 06.00 hours at a pigsty, chicken coop and bovine corral. Culicoides insignis accounted for 81% of the 22,316 specimens collected. Other well-represented species were: Culicoides paucienfuscatus Barbosa (3246 individuals), Culicoides diabolicus Hoffman (308), Culicoides leopoldoi Ortiz (224) and Culicoides duartei Tavares and Luna Dias (221). The remainder accounted for 4% of the total sample. Culicoides insignis occurred mostly at the cattle corral, 98.2% in the rainy season. This study confirms the presence and close association of C. insignis with cattle in Maranhão state, northeastern Brazil and emphasizes the risk of bluetongue infections spreading in the area.


Asunto(s)
Ceratopogonidae/fisiología , Insectos Vectores/fisiología , Estaciones del Año , Animales , Lengua Azul/transmisión , Virus de la Lengua Azul/fisiología , Brasil , Bovinos , Enfermedades de los Bovinos/transmisión , Ceratopogonidae/clasificación , Femenino , Dinámica Poblacional , Medición de Riesgo
7.
Parasitology ; 140(2): 171-80, 2013 02.
Artículo en Inglés | MEDLINE | ID: mdl-22975090

RESUMEN

Heparin-binding proteins (HBPs) play a key role in Trypanosoma cruzi-host cell interactions. HBPs recognize heparan sulfate (HS) at the host cell surface and are able to induce the cytoadherence and invasion of this parasite. Herein, we analysed the biochemical properties of the HBPs and also evaluated the expression and subcellular localization of HBPs in T. cruzi trypomastigotes. A flow cytometry analysis revealed that HBPs are highly expressed at the surface of trypomastigotes, and their peculiar localization mainly at the flagellar membrane, which is known as an important signalling domain, may enhance their binding to HS and elicit the parasite invasion. The plasmon surface resonance results demonstrated the stability of HBPs and their affinity to HS and heparin. Additionally, gelatinolytic activities of 70 kDa, 65·8 kDa and 59 kDa HBPs over a broad pH range (5·5-8·0) were revealed using a zymography assay. These proteolytic activities were sensitive to serine proteinase inhibitors, such as aprotinin and phenylmethylsulfonyl fluoride, suggesting that HBPs have the properties of trypsin-like proteinases.


Asunto(s)
Membrana Celular/metabolismo , Flagelos/enzimología , Proteínas Protozoarias/metabolismo , Serina Proteasas/metabolismo , Trypanosoma cruzi/fisiología , Membrana Celular/enzimología , Activación Enzimática/efectos de los fármacos , Citometría de Flujo , Gelatina/metabolismo , Regulación de la Expresión Génica , Heparina/metabolismo , Interacciones Huésped-Parásitos , Concentración de Iones de Hidrógeno , Unión Proteica , Inhibidores de Serina Proteinasa/farmacología , Trypanosoma cruzi/enzimología
8.
Mutat Res ; 753(1): 42-7, 2013 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-23474391

RESUMEN

Acitretin is currently used alone or combined with PUVA (psoralen + UVA) or with narrow-band ultraviolet B (NBUVB), to treat moderate and severe psoriasis. However, little is known about the potential genotoxic/carcinogenic risk and the cytostatic/cytotoxic effects of these treatments. Our aim was to study the cytotoxic and genotoxic effects of acitretin - alone or in combination with PUVA or NBUVB - by performing studies with blood from patients with psoriasis vulgaris who were treated with acitretin, acitretin+PUVA or acitretin+NBUVB for 12 weeks, and in vitro studies with blood from healthy volunteers, which was incubated with acitretin at different concentrations. The cytotoxic and genotoxic effects were evaluated by the cytokinesis-blocked micronucleus test and the comet assay. Our results show that psoriatic patients treated with acitretin alone or with acitretin+NBUVB, did not show genotoxic effects. In addition, these therapies reduced the rate of proliferation and induced apoptosis and necrosis of lymphocytes; the same occurred with lymphocyte cultures incubated with acitretin (1.2-20µM). The acitretin+PUVA reduced also the proliferation rate, and increased the necrotic lymphocytes. Our studies suggest that therapy with acitretin alone or combined with NBUVB, as used in psoriatic patients, does not show genotoxic effects, reduces the rate of proliferation and induces apoptosis and necrosis of lymphocytes. The combination of acitretin with PUVA also reduces the proliferation rate and increases the number of necrotic lymphocytes. However, as it induced slight genotoxic effects, further studies are needed to clarify its genotoxic potential.


Asunto(s)
Acitretina/toxicidad , Queratolíticos/toxicidad , Linfocitos/efectos de los fármacos , Metoxaleno/toxicidad , Terapia PUVA/efectos adversos , Psoriasis/tratamiento farmacológico , Fármacos Sensibilizantes a Radiaciones/toxicidad , Rayos Ultravioleta/efectos adversos , Acitretina/administración & dosificación , Acitretina/uso terapéutico , Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , División Celular/efectos de los fármacos , División Celular/efectos de la radiación , Terapia Combinada , Ensayo Cometa , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Femenino , Humanos , Queratolíticos/administración & dosificación , Queratolíticos/uso terapéutico , Linfocitos/efectos de la radiación , Masculino , Metoxaleno/administración & dosificación , Metoxaleno/uso terapéutico , Pruebas de Micronúcleos , Persona de Mediana Edad , Necrosis , Fármacos Sensibilizantes a Radiaciones/administración & dosificación , Fármacos Sensibilizantes a Radiaciones/uso terapéutico
9.
J Mech Behav Biomed Mater ; 138: 105583, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36442369

RESUMEN

A home-made 3D Multi-Material Laser Powder Bed Fusion (3DMMLPBF) technology was exploited to manufacture novel multi-material Ti6Al4V-CoCrMo parts. This multi-material concept aims to bring to life a new and disruptive material's design concept for the acetabular cup. Only using a layer-by-layer approach it is possible to manufacture an acetabular cup capable to combine CoCrMo alloy wear resistance and Ti6Al4V alloy bone-friendly nature, in a single component, fabricated at once. This system works with multiple powder deposition functions and vacuum cleaning procedures allowing to use two different powders (Ti6Al4V and CoCrMo) in each layer and thus, allowing to construct 3D Multi-Material transition between distinct materials, point-by-point and layer-by-layer. In this sense, the manufacturing strategies and the functional transition between Ti6Al4V and CoCrMo with a mechanical interlocking were analyzed and discussed both from mechanical and metallurgical point of view. A small diffusion area and no evidence of defects or cracks can be found in the transition's regions between the distinct materials which are strong evidences of a solid metallurgical bonding at the interfacial regions of Ti6Al4V and CoCrMo materials. A functional transition is also obtained through a design capable to provide a 3D mechanical interlocking with potential of assuring, simultaneously, tensile and compressive strength. This proof of concept might be a step-ahead in Laser Powder Bed Fusion in which the most desired intrinsic of individual materials can be combined in a single component targeting biomedical disruptive solutions.


Asunto(s)
Aleaciones , Rayos Láser , Ensayo de Materiales , Polvos
10.
Eur J Paediatr Dent ; 24(2): 112-123, 2023 06 09.
Artículo en Inglés | MEDLINE | ID: mdl-37038757

RESUMEN

Aim: The present study aimed: i) to retrospectively evaluate the expansion movement predicted by the Clincheck® software and the achieved expansion using Invisalign First® in children needing maxillary expansion to correct malocclusions; and ii) to critically compare these clinical results with the outcomes obtained for maxillary expansion using conventional removable and cemented expanders. Material and Methods: The 3D digital models of the dental arches of 24 children undergoing orthodontic treatment exclusively with Invisalign First® aligners between 2018 and 2021 were sequentially selected for this study. Three digital models were analysed: pre-treatment (P0), the Clincheck®-predicted tooth positions (P1), and post-treatment (P2) models. The maxillary dental arch width and expansion efficiency were measured andcalculated. An in-depth review of the available literature on maxillary expansion was performed following PRISMA guidelines. Results: Invisalign First® was able to achieve a total effectiveness of maxillary expansion of 62.6%, compared to the predicted movement. Similarly, the total effectiveness of mandibular expansion was 61.6%. Conclusions: Our data shows that Invisalign First® system can increase the arch width with maxillary expansion effectiveness, providing similar results to those achieved with conventional removable appliances. However, neither Invisalign First® aligners nor conventional removable expanders are as much efficient as cemented-retained appliances.


Asunto(s)
Maloclusión , Aparatos Ortodóncicos Removibles , Niño , Humanos , Estudios Retrospectivos , Técnicas de Movimiento Dental , Resultado del Tratamiento , Dentición Mixta , Maloclusión/terapia
11.
Toxicol Appl Pharmacol ; 265(3): 368-72, 2012 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-22982620

RESUMEN

Ethanolic extract of Casearia sylvestris is thought to be antimutagenic. In this study, we attempted to determine whether this extract and casearin X (a clerodane diterpene from C. sylvestris) are protective against the harmful effects of airborne pollutants from sugarcane burning. To that end, we used the Tradescantia micronucleus test in meiotic pollen cells of Tradescantia pallida, the micronucleus test in mouse bone marrow cells, and the comet assay in mouse blood cells. The mutagenic compound was total suspended particulate (TSP) from air. For the Tradescantia micronucleus test, T. pallida cuttings were treated with the extract at 0.13, 0.25, or 0.50 mg/ml. Subsequently, TSP was added at 0.3mg/ml, and tetrads from the inflorescences were examined for micronuclei. For the micronucleus test in mouse bone marrow cells and the comet assay in mouse blood cells, Balb/c mice were treated for 15 days with the extract-3.9, 7.5, or 15.0 mg/kg body weight (BW)-or with casearin X-0.3, 0.25, or 1.2 mg/kg BW-after which they received TSP (3.75 mg/kg BW). In T. pallida and mouse bone marrow cells, the extract was antimutagenic at all concentrations tested. In mouse blood cells, the extract was antigenotoxic at all concentrations, whereas casearin X was not antimutagenic but was antigenotoxic at all concentrations. We conclude that C. sylvestris ethanolic extract and casearin X protect DNA from damage induced by airborne pollutants from sugarcane burning.


Asunto(s)
Anticarcinógenos/farmacología , Casearia/química , Daño del ADN , Diterpenos de Tipo Clerodano/farmacología , Material Particulado/toxicidad , Extractos Vegetales/farmacología , Saccharum/química , Contaminantes Atmosféricos/toxicidad , Animales , Médula Ósea/efectos de los fármacos , Médula Ósea/metabolismo , Brasil , Ensayo Cometa , Masculino , Ratones , Ratones Endogámicos BALB C , Pruebas de Micronúcleos , Hojas de la Planta/química , Distribución Aleatoria
12.
Materials (Basel) ; 15(18)2022 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-36143744

RESUMEN

Multi-Material Additive Manufacturing for Advanced High-Tech Components is a new open Special Issue of Materials, which aims to publish original and review papers regarding new scientific and applied research and make great contributions to finding, exploring and understanding novel multi-material components via additive manufacturing [...].

13.
J Mech Behav Biomed Mater ; 136: 105508, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36265278

RESUMEN

The development of implant metal-free surfaces has gained attention since non-benefic results have been reported related to the metallic ions released from metal implants to the human body. Ceramic coatings have been proposed as a possible solution however, the detachment of these coatings, during implantation or even in function, can compromise its function. In order to overcome this problem, this work proposes a novel hybrid Ti6Al4V-ZrO2 surface, starting with laser texturing of the Ti6Al4V substrate by Laser Nd:YV04, followed by the allocation of the zirconia (ZrO2) powder and its subsequent sintering by hot pressing process. Results revealed that zirconia strongly adheres to titanium textured surfaces since no detachment was found under tribological and adhesion scratch tests. Moreover, the tribological results showed that the incorporation of zirconia into textured titanium surface reduces significantly the wear rate of titanium (≈93%), which is a good indicator of low metallic particles/ions released to the body. These results suggest that this novel surface with good aesthetic properties and improved wear resistance (given by zirconia) and mechanical resistance (from titanium) can be a promising solution for dental implants, especially for implant/abutment or abutment/ceramic contact zones, and thus have a huge impact on the long-term performance of implants.


Asunto(s)
Implantes Dentales , Titanio , Humanos , Ensayo de Materiales , Titanio/química , Circonio/química , Rayos Láser , Iones , Propiedades de Superficie
14.
J Mech Behav Biomed Mater ; 131: 105246, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35512486

RESUMEN

In this study, Selective Laser Melting (SLM) was used to produce mono-material Ti64Al4V- and NiTi-cubic cellular structures with an open-cell size and wall thickness of 500 µm and 100 µm, respectively. Bioactive beta-tricalcium phosphate (ßTCP) and polymer poly-ether-ether ketone (PEEK) were used to fill the produced structures open-cells, thus creating multi-material components. These structures were characterized in vitro in terms of cell viability, adhesion, differentiation and mineralization. Also, bio-tribological experiments were performed against bovine plate to mimic the moment of implant insertion. Results revealed that metabolic activity and mineralization were improved on SLM mono-material groups, when compared to the control group. All cell metrics were improved with the addition of PEEK, conversely to ßTCP where no significant differences were found. These results suggest that the proposed solutions can be used to improve implants performance.


Asunto(s)
Aleaciones , Prótesis e Implantes , Animales , Bovinos , Éteres , Cetonas/química , Cetonas/farmacología , Ensayo de Materiales , Polietilenglicoles/química , Polímeros/farmacología , Titanio/química , Titanio/farmacología
15.
J Mech Behav Biomed Mater ; 113: 104123, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33032011

RESUMEN

Ti6Al4V sub-millimetric cellular structures arise as promising solutions concerning the progress of conventional orthopedic implants due to its ability to address a combination of mechanical, physical and topological properties. Such ability can improve the interaction between implant materials and surrounding bone leading to long-term successful orthopedic implants. Selective Laser Melting (SLM) capability to produce high quality Ti6Al4V porous implants is in great demand towards orthopedic biomaterials. In this study, Ti6Al4V cellular structures were designed, modeled, SLM produced and characterized targeting orthopedic implants. For that purpose, a set of tools is proposed to overcome SLM limited accuracy to produce porous biomaterials with desired dimensions and mechanical properties. Morphological analyses were performed to evaluate the dimensional deviations noticed between the model CAD and the SLM produced structures. Tensile tests were carried out to estimate the elastic modulus of the Ti6Al4V cellular structures. The present work proposes a design methodology showing the linear correlations found for the dimensions, the porosity and the elastic modulus when comparing the model CAD designs with Ti6Al4V structures by SLM.


Asunto(s)
Rayos Láser , Titanio , Aleaciones , Materiales Biocompatibles , Ensayo de Materiales , Porosidad
17.
J Mech Behav Biomed Mater ; 112: 104049, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32942227

RESUMEN

OBJECTIVES: The aim of this study was to develop a novel design for implants surface functionalization through the production of HAp-coated zirconia structured surfaces by means of hybrid laser technique. The HAp-rich structured surfaces were designed to avoid hydroxyapatite (HAp) coating detachment from the zirconia surface during implant insertion, thus guaranteeing an effective osseointegration. MATERIALS AND METHODS: The functionalization process of zirconia surface started by creating micro-textures using a Nd:YAG laser and subsequent deposition of a HAp coating on the designated locations by dip-coating process. Afterwards, a CO2 laser was used to sinter the HAp coating. The potential of the HAp-coated zirconia structured surfaces was inspected concerning HAp bioactivity preservation, surface wettability, HAp coating adhesion to the textured surfaces and mechanical resistance of zirconia, as assessed by different approaches. RESULTS: The functionalized surfaces exhibited a superhydrophilic behavior (2.30 ± 0.81°) and the remaining results showed that through the hybrid strategy, it is possible to maintain the HAp bioactivity as well as promote a strong adhesion of HAp coating to the textured surfaces even after high energy ultrasonic cavitation tests and friction tests against bovine bone. It was also verified that the flexural strength of zirconia (503 ± 24 MPa) fulfills the strict requirements of the ISO 13356:2008 standard and as such is expectable to be enough for biomedical applications. SIGNIFICANCE: The promising results of this study indicate that the proposed surface design can open the window for manufacturing zirconia-based implants with improved bioactivity required for an effective osseointegration as it avoids the coating detachment problem during the implant insertion.


Asunto(s)
Durapatita , Circonio , Animales , Bovinos , Materiales Biocompatibles Revestidos , Rayos Láser , Propiedades de Superficie , Titanio
18.
J Mech Behav Biomed Mater ; 110: 103891, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32957198

RESUMEN

Nickel-titanium (NiTi) cellular structures are a very promising solution to some issues related to orthopaedic implant failure. These structures can be designed and fabricated to simultaneously address a combination of mechanical and physical properties, such as elastic modulus, porosity, wear and corrosion resistance, biocompatibility and appropriate biological environment. This ability can enhance the modest interaction currently existing between metallic dense implants and surrounding bone tissue, allowing long-term successful orthopaedic implants. For that purpose, NiTi cellular structures with different levels of porosity intended to reduce the elastic modulus were designed, modelled, selective laser melting (SLM) fabricated and characterized. Significant differences were found between the CAD design and the SLM-produced NiTi structures by performing systematic image analysis. This work proposes designing guidelines to anticipate and correct the systematic differences between CAD and produced structures. Compressive tests were carried out to estimate the elastic modulus of the produced structures and finite element analyses were performed, for comparison purposes. Linear correlations were found for the dimensions, porosity, and elastic modulus when comparing the CAD design with the SLM structures. The produced NiTi structures exhibit elastic moduli that match that of bone tissue, which is a good indication of the potential of these structures in orthopaedic implants.


Asunto(s)
Níquel , Titanio , Materiales Biocompatibles , Módulo de Elasticidad , Rayos Láser , Ensayo de Materiales , Porosidad
19.
Mater Sci Eng C Mater Biol Appl ; 108: 110390, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31923937

RESUMEN

The development of new surface designs to enhance the integration process between surgically placed implants and biological tissues remains a challenge for the scientific community. In this way and trying to overcome this issue, in this work, laser technology was explored to produce novel textures on the surface of green zirconia compacts produced by cold pressing technique. Two strategies regarding line design (8 and 16 lines design) and different laser parameters (laser power and number of laser passages) were explored to assess their influence on geometry and depth of created textures. The produced textures were evaluated with Scanning Electron Microscopy (SEM) and it was observed that well-defined textured surfaces with regular geometric features (cavities or pillars) were obtained by laser combining different strategies lines design and parameters. The potential of proposed textures was also evaluated regarding surface wettability, friction performance (static and dynamic coefficient of friction evolution) against bone, aging resistance and flexural strength. Results demonstrated that all the produced textures display a super hydrophilic or hydrophilic behavior. Regarding the friction behavior, it was experimentally observed a high initial static coefficient of friction (COF) for all produced textures. Concerning the aging resistance, all the textured surfaces revealed a low monoclinic content, less than 25% after 5 h of hydrothermal aging. The flexural strength results showed that the mechanical resistance of zirconia was not significantly compromised with the laser action. Based on the obtained results, it is possible to prove that the processing route used for manufacturing the new and different surface designs (cold pressing technique followed by laser texturing) showed to be particularly effective for the production of zirconia implants with customized surface designs according to the properties required in a specific application. These new surface designs besides to enhance the surface wettability and also to improve the fixation at the initial moment of the implantation, do not significantly compromise the resistance to aging and the mechanical performance of zirconia. Hence, a positive impact on the long-term performance of the zirconia implants may be expected with the proposed novel laser textured surface designs.


Asunto(s)
Rayos Láser , Prótesis e Implantes , Circonio/química , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Propiedades de Superficie , Temperatura
20.
Mater Sci Eng C Mater Biol Appl ; 107: 110342, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31761155

RESUMEN

Orthopedic implants are under incessant advancement to improve their interactions with surrounding bone tissue aiming to ensure successful outcomes for patients. A successful biological interaction between implant and surrounding bone depends on the combination of mechanical, physical and topological properties. Hence, Ti6Al4V cellular structures appear as very promising solutions towards the improvement of conventional orthopedic implants. This work addresses a set of fundamental tools that allow improving the design of Ti6Al4V cellular structures produced by Selective Laser Melting (SLM). Three-point bending tests were carried out to estimate the elastic modulus of the produced structures. Morphological analysis allowed to evaluate the dimensional differences that were noticed between the model CAD and the SLM structures. Finite element models (adjusted CAD) were constructed with the experimentally obtained dimensions to replicate the mechanical response of the SLM structures. Linear correlations were systematically found for the dimensions of the SLM structures as a function of the designed model CAD dimensions. This has also been observed for the measured porosities as a function of the designed CAD models. This data can be used in further FE analyses as design guidelines to help engineers fabricating near-net-shape SLM Ti6Al4V cellular structures. Besides, polished and sandblasted surface treatments performed on the Ti6Al4V cellular structures allowed to obtain suitable properties regarding roughness and wettability when compared to as-produced surfaces. The capillarity tests showed that all the analyzed Ti6Al4V structures are able to transport fluid along its structure. The cell viability tests demonstrate Ti6Al4V cellular structures SLM produced did not release toxic substances to the medium, indicating that these structures can assure a suitable environment for cells to proliferate and attach. This study proposes a design methodology for Ti6Al4V cellular structures, that owe suitable mechanical properties but also provide a proper combination of porosity, roughness, wettability, capillarity and cell viability, all of them relevant for orthopedic applications. A Ti6Al4V cellular structured hip implant prototype gathering the suitable features addressed in this study was successfully SLM-produced.


Asunto(s)
Materiales Biocompatibles/química , Prótesis e Implantes , Titanio/química , Aleaciones , Animales , Artroplastia de Reemplazo de Cadera/instrumentación , Fenómenos Biomecánicos , Línea Celular , Supervivencia Celular , Diseño Asistido por Computadora , Módulo de Elasticidad , Fibroblastos , Ensayo de Materiales , Ratones , Porosidad , Propiedades de Superficie
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