Implantes personalizados de polimetilmetacrilato (PMMA) para aplicaciones en craneoplastia

Los implantes a la medida para aplicaciones en craneoplastias tienen el objetivo de restaurar la protección del cerebro que el cráneo proporcionaba y mejorar el aspecto de la superficie después de sufrir un traumatismo o para corregir una malformación. Los principales inconvenientes del procedimiento de craneoplastia incluyen la individualización de la geometría y las propiedades mecánicas del implante para que sea funcional. El objetivo de nuestra investigación fue proponer una metodología integrada para el dise~no biomecánico y fabricación de implantes craneales y aplicarlo a un caso de estudio de un implante personalizado craneofacial para el hueso frontal hecho con polimetilmetacrilato (PMMA) que cumpla con la geometría adecuada y las propiedades mecánicas para su funcionalidad. La primera etapa del procedimiento fue obtener los datos médicos del paciente a través de tomografía axial computarizada (TAC) y luego se realizó un procesamiento de las imágenes para crear un modelo 3D de la región de interés por medio de un software de procesamiento de imágenes. Se desarrollo el diseño del implante utilizando un software CAD y, finalmente, se utilizó la tecnología de prototipado rápido para crear el molde del implante final. La metodología utilizada nos permitió obtener un implante de acuerdo a los requerimientos geométricos y mecánicos. Del mismo modo, se observó que los costos finales de desarrollo del implante individualizado son competitivos, y permite que haya una reducción significativa del tiempo quirúrgico. Igualmente se realizó un análisis biomecánico por medio del método de los elemento finitos como validación del implante con las propiedades del PMMA. Por medio de este se pudo concluir que el PMMA proporciona las condiciones mecánicas suficientes para la protección de las estructuras cerebrales.Abstract. Custom implants for cranioplasty applications have the aim to restore the brain protection that the skull provided and improve the surface appearance after suffring a trauma or to correct a malformation. Major drawbacks of the procedure of cranioplasty include the individualization of the geometry and mechanical properties of the implant to make it functional. The aim of our investigation was to propose an integrated methodology to biomechanical design and manufacturing of cranial implants and apply it to a case study of a craniofacial custom implant for the frontal bone made with Polymethylmethacrylate (PMMA) that meets the suitable geometry and mechanical properties for its functionality. The first process step was to obtain the medical data from the patient through computed tomography; then the images were processed to create a 3D model of the interest region by an imaging processing software; we designed the implant using CAD software and finally we used rapid prototyping technology to create the implant mold to produce the final geometry of the implant. The used methodology allowed us to obtain an implant according to the geometric and mechanical requirements. Likewise, it was observed that the final costs of developing individualized implant are competitive with surgical time savings and further there is an increased quality of the procedure. Similarly a biomechanical analysis was performed using the finite element method as a validation of the implant with the properties of PMMA. Through this it was possible to concluded that the PMMA provides sufficient mechanical conditions for the protection of brain structures.Maestrí

Preconditioning of Bioactive Glasses before Introduction to Static Cell Culture: What Is Really Necessary?

Due to their high bioreactivity, the in-vitro analysis of bioactive glasses (BGs) can be challenging when it comes to maintaining a physiological pH. To improve BG biocompatibility, a heterogenic spectrum of preconditioning approaches, such as “passivation” of the BGs by incubation in cell culture medium, are used but have never been directly compared. In this study, the effect of passivation periods of up to 72 h on pH alkalization and viability of human bone marrow-derived mesenchymal stromal cells was evaluated to determine a time-efficient passivation protocol using granules based on the 45S5-BG composition (in wt%: 45.0 SiO2, 24.5 Na2O, 24.5 CaO, 6.0 P2O5) in different concentrations. pH alkalization was most reduced after passivation of 24 h. Cell viability continuously improved with increasing passivation time being significantly higher after passivation of at least 24 h compared to non-passivated 45S5-BG and the necessary passivation time increased with increasing BG concentrations. In this setting, a passivation period of 24 h presented as an effective approach to provide a biocompatible cell culture setting. In conclusion, before introduction of BGs in cell culture, different passivation periods should be evaluated in order to meet the respective experimental settings, e.g., by following the experimental protocols used in this study

Bioactive glasses incorporating less-common ions to improve biological and physical properties

Bioactive glasses (BGs) have been a focus of research for over five decades for several biomedical applications. Although their use in bone substitution and bone tissue regeneration has gained important attention, recent developments have also seen the expansion of BG applications to the field of soft tissue engineering. Hard and soft tissue repair therapies can benefit from the biological activity of metallic ions released from BGs. These metallic ions are incorporated in the BG network not only for their biological therapeutic effects but also in many cases for influencing the structure and processability of the glass and to impart extra functional properties. The “classical” elements in silicate BG compositions are silicon (Si), phosphorous (P), calcium (Ca), sodium (Na), and potassium (K). In addition, other well-recognized biologically active ions have been incorporated in BGs to provide osteogenic, angiogenic, anti-inflammatory, and antibacterial effects such as zinc (Zn), magnesium (Mg), silver (Ag), strontium (Sr), gallium (Ga), fluorine (F), iron (Fe), cobalt (Co), boron (B), lithium (Li), titanium (Ti), and copper (Cu). More recently, rare earth and other elements considered less common or, some of them, even “exotic” for biomedical applications, have found room as doping elements in BGs to enhance their biological and physical properties. For example, barium (Ba), bismuth (Bi), chlorine (Cl), chromium (Cr), dysprosium (Dy), europium (Eu), gadolinium (Gd), ytterbium (Yb), thulium (Tm), germanium (Ge), gold (Au), holmium (Ho), iodine (I), lanthanum (La), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), nitrogen (N), palladium (Pd), rubidium (Rb), samarium (Sm), selenium (Se), tantalum (Ta), tellurium (Te), terbium (Tb), erbium (Er), tin (Sn), tungsten (W), vanadium (V), yttrium (Y) as well as zirconium (Zr) have been included in BGs. These ions have been found to be particularly interesting for enhancing the biological performance of doped BGs in novel compositions for tissue repair (both hard and soft tissue) and for providing, in some cases, extra functionalities to the BG, for example fluorescence, luminescence, radiation shielding, anti-inflammatory, and antibacterial properties. This review summarizes the influence of incorporating such less-common elements in BGs with focus on tissue engineering applications, usually exploiting the bioactivity of the BG in combination with other functional properties imparted by the presence of the added elements

PLASTIMONIUM, plastilina como una manera divertida para apropiación del patrimonio. Exposiciones de resultados.

This is a short article that summarizes some of the experiences of the social projection project “Plastimonium, Plastilina as a didactic strategy for the dissemination of heritage”, a dissemination strategy of the research project “Tunjan heritage locator.” Plastimonium is a project initially aimed at children with the aim of disseminating Tunja’s architectural heritage, proposing a didactic strategy for raising awareness and recognition of the value of the City’s Heritage of Cultural Interest. An exploratory research was carried out, with a structure that could be made more flexible after the confinement and different points of view were taken into account according to the partial results. A primary research method was used as part of the qualitative methodology based on direct observation of children’s attitudes during the workshops and results measured from surveys and interviews. The practice was developed with an active and participatory methodology. The results have been satisfactory in children and young people and the experiences have continued to be replicated even after the end of the initial project activities.El presente es un artículo corto que resume algunas de las experiencias del proyecto de proyección social “Plastimonium, Plastilina como estrategia didáctica para la difusión del patrimonio”, estrategia de difusión del proyecto de investigación “dLocalizador patrimonial tunjano”. Plastimonium es un proyecto inicialmente dirigido a niños con el objetivo de difundir el patrimonio arquitectónico de Tunja, planteando una estrategia didáctica para la sensibilización y reconocimiento del valor de los Bienes de Interés Cultural de la ciudad. Se realizó una investigación de tipo exploratorio, con una estructura que pudo flexibilizarse a raíz del confinamiento y se tuvieron presentes distintos puntos de vista de acuerdo con los resultados parciales. Se utilizó un método de investigación primario como parte de la metodología cualitativa a partir de la observación directa de las actitudes de los niños durante los talleres y de los resultados medidos a partir de encuestas y entrevistas. La práctica se desarrolló con una metodología activa y participativa. Los resultados han sido satisfactorios en niños y jóvenes y las experiencias se han continuado replicando aún después de terminar las actividades iniciales del proyecto

Facile Preparative Access to Bioactive Silicon Oxycarbides with Tunable Porosity

In the present work, Ca-containing silicon oxycarbides (SiCaOC) with varying Ca content have been synthesized via sol-gel processing and thermal treatment in inert gas atmosphere (pyrolysis). It has been shown that the as-prepared SiCaOC materials with low Ca loadings (Ca/Si molar ratios = 0.05 or 0.12) were X-ray amorphous; their glassy network contains Q(3) sites, indicating the presence of Ca2+ at non-bridging-oxygen sites. SiCaOC with high Ca content (i.e., Ca/Si molar ratio = 0.50) exhibits the presence of crystalline calcium silicate (mainly pseudowollastonite). Furthermore, it has been shown that the incorporation of Ca into the SiOC glassy network has a significant effect on its porosity and specific surface area. Thus, the as-prepared Ca-free SiOC material is shown to be non-porous and having a specific surface area (SSA) of 22.5 m(2)/g; whereas SiCaOC with Ca/Si molar ratio of 0.05 exhibits mesoporosity and a SSA value of 123.4 m(2)/g. The further increase of Ca content leads to a decrease of the SSA and the generation of macroporosity in SiCaOC; thus, SiCaOC with Ca/Si molar ratio of 0.12 is macroporous and exhibits a SSA value of 39.5 m(2)/g. Bioactivity assessment in simulated body fluid (SBF) confirms the hydroxyapatite formation on all SiCaOC samples after seven days soaking, unlike the relatively inert ternary silicon oxycarbide reference. In particular, SiCaOC with a Ca/Si molar ratio of 0.05 shows an increased apatite forming ability compared to that of SiCaOC with Ca/Si molar ratio of 0.12; this difference is considered to be a direct consequence of the significantly higher SSA of the sample with the Ca/Si ratio of 0.05. The present work indicates two effects of Ca incorporation into the silicon oxycarbide glassy network on its bioactivity: Firstly, Ca2+ is shown to contribute to the slight depolymerization of the network, which clearly triggers the hydroxyapatite formation (compare the bioactive behavior of SiOC to that of SiCaOC with Ca/Si molar ratio 0.12 upon SBF exposure); secondly, the Ca2+ incorporation seems to strongly affect the porosity and SSA in the prepared SiCaOC materials. There is an optimum of Ca loading into the silicon oxycarbide glassy network (at a Ca/Si molar ration of 0.05), which provides mesoporosity and reaches maximum SSA, both highly beneficial for the bioactive behavior of the materials. An increase of the Ca loading leads, in addition to the crystallization of calcium silicates, to a coarsening of the pores (i.e., macroporosity) and a significant decrease of the SSA, both negatively affecting the bioactivity

Effect of Sr, Mg and Fe substitution on thephysico-chemical and biological properties ofSi Ca P multilayer scaffolds

tIn this work, a new combination of ceramic materials is proposed for bone tissue engi-neering applications. Multilayer scaffolds consisting of a core composed mainly of calciumpyrophosphate and external coatings of silica and calcium doped with Fe3+, Sr2+and Mg2+were prepared. To study the influence of the arrangement of dopant ions in the externalcoatings, two different scaffolds were developed: scaffolds 3J consisting of a single exter-nal coating with 9 mol% of Fe3+, Sr2+and Mg2+ions; and scaffolds 3S comprising threeexternal coatings, each containing 3 mol% of Fe3+, Sr2+and Mg2+ions. Scaffolds were physico-chemically characterized and evaluated for in vitro bioactivity and cellular response in thepresence of MG-63 cells. The results showed that the core scaffold displayed no in vitro bioac-tivity or good cellular response, but served as a support for the external coatings given itsmechanical resistance. The cell viability of scaffolds 3J and 3S increased more than 100%in relation to the core, and also improved cell proliferation and adhesion resulting in adense layer of cells that covered the scaffolds’ entire surface. The arrangement of ions inthe external coatings did not influence the cellular response, but determined the bioactivityrate

A new population of the hooded antpitta (Grallaricula cucullata: Grallaridae) for the Colombian Central Andes

We report a new population of the Hooded Anpitta (Grallariculla cucullata) in the Central Andes of Colombia, a threatened bird species inhabiting montane cloud forests in Colombian and Venezuelan Andes. We present capture-rate data, which suggest the occurrence of a resident with the highest population size reported for this bird species.Presentamos una nueva población del Tororoi Cabecirrufo (Grallariculla cucullata), una especie de ave amenazada de los bosques montanos nublados de los Andes de Colombia y Venezuela. Presentamos datos de tasas de captura que indican la presencia de una población residente con el tamaño poblacional más alto reportado para la especie

Facile Preparative Access to Bioactive Silicon Oxycarbides with Tunable Porosity

In the present work, Ca-containing silicon oxycarbides (SiCaOC) with varying Ca content have been synthesized via sol-gel processing and thermal treatment in inert gas atmosphere (pyrolysis). It has been shown that the as-prepared SiCaOC materials with low Ca loadings (Ca/Si molar ratios = 0.05 or 0.12) were X-ray amorphous; their glassy network contains Q³ sites, indicating the presence of Ca²⁺ at non-bridging-oxygen sites. SiCaOC with high Ca content (i.e., Ca/Si molar ratio = 0.50) exhibits the presence of crystalline calcium silicate (mainly pseudowollastonite). Furthermore, it has been shown that the incorporation of Ca into the SiOC glassy network has a significant effect on its porosity and specific surface area. Thus, the as-prepared Ca-free SiOC material is shown to be non-porous and having a specific surface area (SSA) of 22.5 m²/g; whereas SiCaOC with Ca/Si molar ratio of 0.05 exhibits mesoporosity and a SSA value of 123.4 m²/g. The further increase of Ca content leads to a decrease of the SSA and the generation of macroporosity in SiCaOC; thus, SiCaOC with Ca/Si molar ratio of 0.12 is macroporous and exhibits a SSA value of 39.5 m²/g. Bioactivity assessment in simulated body fluid (SBF) confirms the hydroxyapatite formation on all SiCaOC samples after seven days soaking, unlike the relatively inert ternary silicon oxycarbide reference. In particular, SiCaOC with a Ca/Si molar ratio of 0.05 shows an increased apatite forming ability compared to that of SiCaOC with Ca/Si molar ratio of 0.12; this difference is considered to be a direct consequence of the significantly higher SSA of the sample with the Ca/Si ratio of 0.05. The present work indicates two effects of Ca incorporation into the silicon oxycarbide glassy network on its bioactivity: Firstly, Ca²⁺ is shown to contribute to the slight depolymerization of the network, which clearly triggers the hydroxyapatite formation (compare the bioactive behavior of SiOC to that of SiCaOC with Ca/Si molar ratio 0.12 upon SBF exposure); secondly, the Ca²⁺ incorporation seems to strongly affect the porosity and SSA in the prepared SiCaOC materials. There is an optimum of Ca loading into the silicon oxycarbide glassy network (at a Ca/Si molar ration of 0.05), which provides mesoporosity and reaches maximum SSA, both highly beneficial for the bioactive behavior of the materials. An increase of the Ca loading leads, in addition to the crystallization of calcium silicates, to a coarsening of the pores (i.e., macroporosity) and a significant decrease of the SSA, both negatively affecting the bioactivity

Bioactive Glass (BG) ICIE16 Shows Promising Osteogenic Properties Compared to Crystallized 45S5-BG

The ICIE16-bioactive glass (BG) (48.0 SiO2, 6.6 Na2O, 32.9 CaO, 2.5 P2O5, 10.0 K2O (wt %)) has been developed as an alternative to 45S5-BG, the original BG composition (45.0 SiO2, 24.5 Na2O, 24.5 CaO, 6.0 P2O5 (wt %)), with the intention of broadening the BG sintering window while maintaining bioactivity. Because there is a lack of reports on ICIE16-BG biological properties, the influence of ICIE16-BG on viability, proliferation, and osteogenic differentiation of human mesenchymal stromal cells (MSCs) was evaluated in direct comparison to 45S5-BG in this study. The BGs underwent heat treatment similar to that which is required in order to fabricate scaffolds by sintering, which resulted in crystallization of 45S5-BG (45S5-CBG) while ICIE16 remained amorphous. Granules based on both BGs were biocompatible, but ICIE16-BG was less harmful to cell viability, most likely due to a more pronounced pH alkalization in the 45S5-CBG group. ICIE16-BG outperformed 45S5-CBG in terms of osteogenic differentiation at the cellular level, as determined by the increased activity of alkaline phosphatase. However, granules from both BGs were comparable regarding the stimulation of expression levels of genes encoding for osseous extracellular matrix (ECM) proteins. The addition of therapeutically active ions to ICIE16-BG might further improve its ability to stimulate ECM production and should be investigated in upcoming studies