A Comparison of Mechanical Properties of Different Hydroxyapatite (HAp) Based Nanocomposites: The Influence of Morphology and Preferential Orientation.

Three different types of hydroxyapatite (HAp) based porous ceramic materials were obtained through the modified gel casting method; one of them was made of commercial HAp particles and used as a reference in the mechanical characterization. Other type of ceramic was elaborated using HAp nanofibers, which were synthesized through the microwave assisted hydrothermal method and they possess a high crystallinity, purity and a preferential crystalline orientation in the [300], such were grown along the [001]. The third type of porous ceramic was elaborated using a combination of HAp nanofibers and particles. The HAp nanofibers and particles were previously analyzed by using X-ray diffraction to study their crystal structure, the topology and morphology of those HAp aggregates were observed with scanning electron microscopy (SEM); high-resolution transmission electron microscopy was useful to carry out a detailed crystallographic analysis. Afterwards, an organic phase made of gelatin was added to the porous ceramics in order to obtain nanocomposite materials. Two different concentrations of gelatin were used separately, and the combination of three types of porous ceramics and two concentrations of gelatin produced six different nanocomposite materials. All of these composite materials were observed through the SEM to see their topology and porosity and after that, they were probed under compression tests and their corresponding mechanical behavior was analyzed. All the composites showed mechanical properties similar to those observed in cellular materials. The Young modulus and ultimate strength were compared, finally, it was determined the contribution to the mechanical properties of the morphology, crystalline quality and preferential crystalline orientation in the HAp nanofibers. According to such properties, the composite material made of HAp nanofibers has bone tissue implant potential applications.

Interconnected porosity analysis by 3D X-ray microtomography and mechanical behavior of biomimetic organic-inorganic composite materials.

Hydroxyapatite-based materials have been used for dental and biomedical applications. They are commonly studied due to their favorable response presented when used for replacement of bone tissue. Those materials should be porous enough to allow cell penetration, internal tissue growth, vascular incursion and nutrient supply. Furthermore, their morphology should be designed to guide the growth of new bone tissue in anatomically applicable ways. In this work, the mechanical performance and 3D X-ray microtomography (X-ray µCT) study of a biomimetic, organic-inorganic composite material, based on hydroxyapatite, with physicochemical, structural, morphological and mechanical properties very similar to those of natural bone tissue is reported. Ceramic pieces in different shapes and several porous sizes were produced using a Modified Gel Casting Method. Pieces with a controlled and 3D hierarchical interconnected porous structure were molded by adding polymethylmethacrylate microspheres. Subsequently, they were subject to a thermal treatment to remove polymers and to promote a sinterization of the ceramic particles, obtaining a HAp scaffold with controlled porosity. Then, two different organic phases were used to generate an organic-inorganic composite material, so gelatin and collagen, which was extracted from bovine tail, were used. The biomimetic organic-inorganic composite material was characterized by Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, X-ray Diffraction, Fourier Transform Infrared Spectroscopy and 3D X-ray microtomography techniques. Mechanical properties were characterized in compression tests, obtaining a dramatic and synergic increment in the mechanical properties due to the chemical and physical interactions between the two phases and to the open-cell cellular behavior of the final composite material; the maximum compressive strength obtained corresponds to about 3 times higher than that reported for natural cancellous bone. The pore size distribution obtained could be capable to allow cell penetration, internal tissue in-growth, vascular incursion and nutrient supply and this material has tremendous potential for use as a replacement of bone tissue or in the manufacture and molding of prosthesis with desired shapes.

Intraventricular hemorrhage treated with intraventricular fibrinolysis. A 10-year experience

Purpose We evaluate the results and complications of our intraventricular fibrinolysis protocol. Material and methods A retrospective analysis was made of the cases of intraventricular hemorrhage with 13-bed Intensive Care Unit. Graeb score 6 or above subjected to intraventricular fibrinolysis. We gathered demographic parameters, clinical risk scores, tomography data and case histories showing neurological status and complications related to intraventricular treatment. The results between those who died and the survivors were compared. Results Intraventricular fibrinolysis was performed in 42 patients (69% males) with intraventricular hemorrhage. The average age was 58.36 years (SD 16.67), with a median APACHE II score of 17.5 (r 3–29). A total of 16.7% were receiving acenocoumarol, and 7.1% were on antiplatelet drugs. The median Glasgow Coma Score at the start of treatment was 8 (r 3–13). The median Graeb score was 9 (r 6–12), and was severe (Graeb 9–12) in almost 62%. In turn, 26.2% of the patients developed ventriculitis, and there was further bleeding in 7.1%. Death occurred in 50% of the cases. None of the analyzed variables were significantly related to increased mortality. In the 21 survivors, the Glasgow Outcome Score at 3 months was 2 in 23.8% of the cases, 3 in 28.57%, 4 in 23.8% and 5 in 28.57% of the patients. Conclusions Intraventricular fibrinolysis does not appear to involve a high rate of complications, and may result in lesser mortality, with a better functional outcome after three months than that estimated and published in the literature in reference to intraventricular hemorrhage (AU)

Objetivo Evaluar los resultados y complicaciones de un protocolo de fibrinólisis intraventricular empleado durante 10 años. Ámbito de aplicación y métodos Servicio de Medicina Intensiva de 13 camas. Análisis retrospectivo de nuestra base prospectiva de pacientes con hemorragia intraventricular con Graeb mayor de 5 tratados con fibrinólisis intraventricular. Registramos datos demográficos, escalas de gravedad, datos tomográficos y evolutivos neurológicos, y complicaciones relacionadas con la fibrinólisis. Comparamos los resultados entre fallecidos y supervivientes. Resultados Recibieron fibrinolíticos intraventriculares 42 pacientes (69% varones) con hemorragia intraventricular. La edad media fue 58,36 años (DE 16,67), con una mediana de APACHE II de 17,5 (rango 3-29). El 16,7% tomaban acenocumarol y el 7,1% estaban en tratamiento antiagregante. La mediana del Glasgow Coma Score en el momento de inicio de la fibrinólisis fue de 8 (rango 3-13), y la mediana de Graeb fue 9 (rango 6-12). Más del 62% de las hemorragias fueron clasificadas como graves (Graeb 9-12). Se complicaron con ventriculitis el 26,2% y con sangrado el 7,1%. Falleció el 50% de la serie. Ninguna de las variables analizadas se relacionó de modo significativo con la mortalidad. De los 21 supervivientes, el Glasgow Out come Score a los 3 meses fue de 2 en el 23,8%, de 3 en el 28,57%, de 4 en el 23,8% y de 5 en el 28,57%.ConclusionesLa fibrinólisis intraventricular no parece asociar una alta tasa de complicaciones, y puede contribuir a una menor mortalidad con mejor resultado funcional a los 3 meses que la estimada y publicada en la hemorragia intraventricular (AU)

Intraventricular hemorrhage treated with intraventricular fibrinolysis. A 10-year experience.

PURPOSE: We evaluate the results and complications of our intraventricular fibrinolysis protocol. MATERIAL AND METHODS: A retrospective analysis was made of the cases of intraventricular hemorrhage with 13-bed Intensive Care Unit. Graeb score 6 or above subjected to intraventricular fibrinolysis. We gathered demographic parameters, clinical risk scores, tomography data and case histories showing neurological status and complications related to intraventricular treatment. The results between those who died and the survivors were compared. RESULTS: Intraventricular fibrinolysis was performed in 42 patients (69% males) with intraventricular hemorrhage. The average age was 58.36 years (SD 16.67), with a median APACHE II score of 17.5 (r 3-29). A total of 16.7% were receiving acenocoumarol, and 7.1% were on antiplatelet drugs. The median Glasgow Coma Score at the start of treatment was 8 (r 3-13). The median Graeb score was 9 (r 6-12), and was severe (Graeb 9-12) in almost 62%. In turn, 26.2% of the patients developed ventriculitis, and there was further bleeding in 7.1%. Death occurred in 50% of the cases. None of the analyzed variables were significantly related to increased mortality. In the 21 survivors, the Glasgow Outcome Score at 3 months was 2 in 23.8% of the cases, 3 in 28.57%, 4 in 23.8% and 5 in 28.57% of the patients. CONCLUSIONS: Intraventricular fibrinolysis does not appear to involve a high rate of complications, and may result in lesser mortality, with a better functional outcome after three months than that estimated and published in the literature in reference to intraventricular hemorrhage.