Bone regeneration in a rabbit critical femoral defect by means of magnetic hydroxyapatite macroporous scaffolds.

Magnetic scaffolds have recently attracted significant attention in tissue engineering due to the prospect of improving bone tissue formation by conveying soluble factors such as growth factors, hormones, and polypeptides directly to the site of implantation, as well as to the possibility of improving implant fixation and stability. The objective of this study was to compare bone tissue formation in a preclinical rabbit model of critical femoral defect treated either with a hydroxyapatite (HA)/magnetite (90/10 wt %) or pure HA porous scaffolds at 4 and 12 weeks after implantation. The biocompatibility and osteogenic activity of the novel magnetic constructs was assessed with analysis of the amount of newly formed bone tissue and its nanomechanical properties. The osteoconductive properties of the pure HA were confirmed. The HA/magnetite scaffold was able to induce and support bone tissue formation at both experimental time points without adverse tissue reactions. Biomechanically, similar properties were obtained from nanoindentation analysis of bone formed following implantation of magnetic and control scaffolds. The results indicate that the osteoconductive properties of an HA scaffold are maintained following inclusion of a magnetic component. These provide a basis for future studies investigating the potential benefit in tissue engineering of applying magnetic stimuli to enhance bone formation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 546-554, 2018.

Evaluación de teóricos on-line en la Cátedra de Odontología Integral Niños / Evaluation of online theoreticals at the Department of Comprehensive Dentistry for Children

Los objetivos de este trabajo fueron conocer la percepción de estudiantes y docentes sobre la implementación de la modalidad de clases expositivas on-line, estimar la frecuencia y oportunidad de acceso por parte de los alumnos y comparar los resultados obtenidos en las calificaciones finales obtenidas con la modalidad teórico presencial y la on-line. El recurso resultó positivo para el 80,62% y 73,33% de alumnos y docentes respectivamente. Los primeros ingresaron cada uno un promedio de 2,75±1,45 veces a cada uno de los 15 módulos y el 60.45% lo hizo 15 días antes del examen. No hubo diferencias entre las calificaciones obtenidas entre dos cohortes que utilizaron las diferentes modalidades. Se concluyó que la modalidad on-line con clase de repaso presencial fue percibida como apropiada y con contenidos relevantes. Fue utilizada por los estudiantes como una herramienta de consulta, con amplia flexibilidad horaria y en reiteradas oportunidades, sin restarle horas a la atención de pacientes (AU)

Modifying bone scaffold architecture in vivo with permanent magnets to facilitate fixation of magnetic scaffolds.

The fundamental elements of tissue regeneration are cells, biochemical signals and the three-dimensional microenvironment. In the described approach, biomineralized-collagen biomaterial functions as a scaffold and provides biochemical stimuli for tissue regeneration. In addition superparamagnetic nanoparticles were used to magnetize the biomaterials with direct nucleation on collagen fibres or impregnation techniques. Minimally invasive surgery was performed on 12 rabbits to implant cylindrical NdFeB magnets in close proximity to magnetic scaffolds within the lateral condyles of the distal femoral epiphyses. Under this static magnetic field we demonstrated, for the first time in vivo, that the ability to modify the scaffold architecture could influence tissue regeneration obtaining a well-ordered tissue. Moreover, the association between NdFeB magnet and magnetic scaffolds represents a potential technique to ensure scaffold fixation avoiding micromotion at the tissue/biomaterial interface.

Innovative magnetic scaffolds for orthopedic tissue engineering.

The use of magnetism in tissue engineering is a very promising approach, in fact magnetic scaffolds are able not only to support tissue regeneration, but they can be activated and work like a magnet attracting functionalized magnetic nanoparticles (MNPs) injected close to the scaffold enhancing tissue regeneration. This study aimed to assess the in vivo biocompatibility and osteointegrative properties of novel magnetic scaffolds. Two hydroxyapatite/collagen (70/30 wt %) magnetic scaffolds were magnetized with two different techniques: direct nucleation of biomimetic phase and superparamagnetic nanoparticles (MNPs) on self-assembling collagen fibers (MAG-A) and scaffold impregnation in ferro-fluid solution (MAG-B). Magnetic scaffolds were implanted in rabbit distal femoral epiphysis and tibial mid-diaphysis. Histopathological screening showed no inflammatory reaction due to MNPs. Significantly higher bone healing rate (ΔBHR) results were observed in MAG-A in comparison to MAG-B. Significant differences were also found between experimental times with an increase in ΔBHR from 2 to 4 weeks for both scaffolds in trabecular bone, while only for MAG-B (23%, p < 0.05) in cortical bone. The proposed magnetic scaffolds seem to be promising for magnetic guiding in orthopedic tissue engineering applications and they will be suitable to treat also several pathologies in regenerative medicine area.

The use of low-frequency vocalizations in African elephant(Loxodonta africana) reproductive strategies.

Fertility-advertisement calls in females are predicted to occur in nonmonogamous species where males and females are widely separated in space. In African elephants, low-frequency vocalizations have thus been suggested as a reproductive strategy used by fertile females to attract mates. This study examined the use of low-frequency vocalizations with respect to different phases of the estrous cycle in African elephants by simultaneously monitoring vocalizations, behavior, and hormonal profiles. Subjects were one male and six female African elephants housed at Disney's Animal Kingdom. No acoustically distinct vocalizations were restricted to the ovulatory follicular phase. However, overall rate of low-frequency vocalization as well as the rate of one acoustically distinct vocalization changed over the estrous cycle, with highest rates of calling related to the first period of follicular growth, or anovulatory follicular phase. Elevated rates of vocalization thus were not restricted to behavioral estrus and occurred much earlier in the estrous cycle than in most species that produce fertility-advertisement calls. Both herd composition and elephant identity also affected rates of vocalization. Vocalizations therefore may not be reliable signals of actual fertility. However, the increase in vocalizations in advance of estrus may attract males to the herd prior to ovulation, facilitating both male-male competition and female choice. Once present in the herd, males may then switch strategies to use more reliable chemical and visual cues to detect ovulating females.

Características clínicas y factores de riesgo asociados a hipomineralización molar incisiva / Clinical features and risk factors associated to molar-incisor hypomineralization

La hipomineralización molar incisiva (MIH), entidad clínica de etiología desconocida, tiene actualmente fuerte impacto en las necesidades de tratamiento odntopediátrico por la frecuencia y severidad de las lesiones OBJETIVOS: Estimar el riesgo relativo de algunas variables asociadas a MIH. Valorar las características clínicas yseveridad de las lesiones de MIH. Estimar el riesgo relativo de los defectos de esmalte en molares, en relación a lapresencia de opacidades en los incisivos. SUJETOS Y MÉTODOS: Se incluyeron 98 niños con MIH que concurrieron para su atención a 4 consultorios privados de CABA de odontopediatras docentes de FOUBA, cuyas madres accedieron a completar una encuesta indagando sobre la historia del niño. El grupo control se constituyó con 98 niños sin HMI de igual sexo y edad provenientes de los mismos consultorios. Fue estimado el riesgo relativo utilizando Odds Ratio (IC 95%). Se realizó la evaluación clínica para registrar: caras dentarias afectadas, extensión, severidad e hipersensibilidad. RESULTADOS: Se encontraron asociaciones positivas con infecciones respiratorias, ingesta de leches especiales y administración deantiinflamatorios no esteroides. Se registraron 286 molares y 254 incisivos afectados. El orden de frecuenciaobservada fue: molares inferiores, molares superiores, incisivos centrales superiores, incisivos centrales inferiores,incisivos laterales superiores e incisivos laterales inferiores. El 80,61 por ciento presentaban 1 ó más incisivos afectadosy el 41,83 por ciento presentaban afectados los 4 molares; de loscuales el 44,5 por ciento reportaron sensibilidad. Se encontró asociaciónpositiva de lesiones en molares con lesiones en incisivos. CONCLUSIONES: La etiología de la Hipomineralización molar incisiva permanece aún poco clara,observándose en este trabajo la asociación mas firme con la ingesta de antiinflamatorios no esteroides

Vinculación entre actividad cariógena y cobertura social en niños / Link between cariogenic activity and social coverage in children

Ante los altos valores e incremento de patología de caries en la última década observados en un trabajo anterior (SAIO, 1998), y dado que su prevalencia se encuentra asociada a determinantes socioeconómicos y educativos, el objetivo de este trabajo fue comparar inidcadores clínicos de actividad cariogénica en pacientes pertenecientes a diferentes sectores de atención: A: Privado (Modalidad prepago). B: Obra Social, C: Público Arancelado Universitario. La información de las Historias Clínicas de 409 pacientes entre 2 y 17 años fue volcada en una base de datos donde se analizaron separadamente piezas primarias y permanentes. Se registraron, edad, ceos o CPOS, y prestaciones realizadas, que fueron evaluados estadísticamente a través de ANOVA y comparaciones múltiples, obteniéndose los siguientes resultados: La edad media más tardía de consulta se consignó en B (dentición primaria: 9,36+2,16, permanente: 11,43+2,45). Con respecto a la patología, los niveles más bajos se observaron en A: ceos: 1,74+2,9, CPOS: 1,77+2,93, ceos=0: 56,88 por ciento y CPOS=0: 53,96 por ciento, mientras que los más altos fueron registrados en C: ceos: 7,83+6,98, CPOS: 5,77+5,11, ceos=0: 6 por ciento, CPOS=0 10 por ciento. En relación con el tipo de prácticas realizadas, el mayor registro de preventivas en aambas denticiones se obtuvo en C. Conclusiones: De los resultados obtenidos se confirma la relación del compromiso social con los niveles de patología y puede inferirse que los intereses de los distintos sectores de atención condiciona las prácticas realizadas por los profesionales