Effect of nano-sized bioactive glass particles on the angiogenic properties of collagen based composites.

Angiogenesis is essential for tissue regeneration and repair. A growing body of evidence shows that the use of bioactive glasses (BG) in biomaterial-based tissue engineering (TE) strategies may improve angiogenesis and induce increased vascularization in TE constructs. This work investigated the effect of adding nano-sized BG particles (n-BG) on the angiogenic properties of bovine type I collagen/n-BG composites. Nano-sized (20-30 nm) BG particles of nominally 45S5 Bioglass® composition were used to prepare composite films, which were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The in vivo angiogenic response was evaluated using the quail chorioallantoic membrane (CAM) as an model of angiogenesis. At 24 h post-implantation, 10 wt% n-BG containing collagen films stimulated angiogenesis by increasing by 41 % the number of blood vessels branch points. In contrast, composite films containing 20 wt% n-BG were found to inhibit angiogenesis. This experimental study provides the first evidence that addition of a limited concentration of n-BG (10 wt%) to collagen films induces an early angiogenic response making selected collagen/n-BG composites attractive matrices for tissue engineering and regenerative medicine.

Histomorphometric and microchemical characterization of maturing dental enamel in rats fed a boron-deficient diet.

Few reports are available in the literature on enamel formation under nutritional deficiencies. Thus, we performed a study to determine the effects of boron (B) deficiency on the maturing dental enamel, employing the rat continuously erupting incisor as the experimental model. Male Wistar rats, 21 days old, were used throughout. They were divided into two groups, each containing ten animals: +B (adequate; 3-mg B/kg diet) and -B (boron deficient; 0.07-mg B/kg diet). The animals were maintained on their respective diets for 14 days and then euthanized. The mandibles were resected, fixed, and processed for embedding in paraffin and/or methyl methacrylate. Oriented histological sections of the continuously erupting incisor were obtained at the level of the mesial root of the first molar, allowing access to the maturation zone of the developing enamel. Dietary treatment did not affect food intake and body weight. Histomorphometric evaluation using undecalcified sections showed a reduction in enamel thickness (hypoplasia), whereas microchemical characterization by energy-dispersive X-ray spectrometry did not reveal alterations in enamel mineralization.

Biocompatibility and bone mineralization potential of 45S5 Bioglass-derived glass-ceramic scaffolds in chick embryos.

The aim of the present study was to evaluate the biocompatibility and bone mineralization potential of 45S5 Bioglass-derived glass-ceramic scaffolds using a chick embryo shell-less (ex ovo) culture system. Chick embryos were divided into two groups: control (C) and experimental (E). Scaffolds were placed on the chorioallantoic membrane (CAM) in embryos of group E at 10 days of total incubation. The 45S5 Bioglass-derived glass-ceramic scaffolds proved to be biocompatible in terms of the absence of inflammatory response at the implant site (CAM). Moreover, no alterations in the other end-points assessed, i.e. survival, stage of embryonic development and body weight, were detected. However, body length was greater in group E embryos than in group C embryos (p0.05). A marked reduction (93%) in Ca content in the scaffolds was evidenced by energy-dispersive X-ray analysis at 5 days post-implantation. Calcium release from the scaffold implanted on the CAM might have been responsible for the restoration of the bone-like phenotype in chick embryonic skeleton of group E as detected by Alcian blue-Alizarin red double staining, as well as by histological and microchemical analyses. Conversely, the control embryos exhibited a chondrogenic phenotype.

Fauna de anuros en la ciudad de Salta, Argentina / Anuran fauna from Salta City, Argentina

The loss and transformation of habitat by anthropogenic activities is one of the main causes of biodiversity decrease. Amphibians are declining all over the world and one of the causes of this decline is thought to be habitat reduction. However, there are anuran populations in highly disturbed habitats, like cities. This study presents the ecological baseline needed to understand anuran communities in urban environments, for Salta City, Argentina (ca. 502 000 inhabitants). The sample was stratified by environments defined by infrastructure and geographic location. The species were identified by visual encounter techniques and by auditory transect during the 2002-2003 reproductive period. Three families, seven genera and twelve species were recorded and the species richness decreased from city border to center. Similarity index values among geographic areas was higher East-West (94.7) than South-West (33.3). Bufo arenarum was the only species recorded in all environments. Hyla andina and Odontophrynus americanus had a restricted distribution and are here considered vulnerable. The border effect can explain some distribution pattern in these populations. A map of the potential distribution of recorded species for Salta is provided

La pérdida y transformación del hábitat generado por actividades humanas es una de las principales causas de disminución de biodiversidad. Los anfibios constituyen un grupo en franca declinación a nivel global debido a múltiples motivos, entre ellos la reducción de sus hábitats; sin embargo, se observan poblaciones de anuros en ambientes altamente antropizados como las ciudades. El objetivo del trabajo fue recabar información de base ecológicamente necesaria para comprender la distribución de las comunidades de anuros en estos ambientes. Para ello, se efectuó el inventario de la fauna de anuros del ejido urbano de la Ciudad de Salta, Argentina, con una población estimada en 502 316 habitantes. Se diseñó el muestreo por ambientes, caracterizándolos en función del tipo de infraestructura urbana y su ubicación por zonas geográficas. La identificación de las especies se realizó a partir de técnicas de encuentro visual y transecta auditiva, abarcando la temporada reproductiva 2002-2003. Se detectaron tres familias, siete géneros y doce especies, observando una disminución de la riqueza desde los bordes hacia el centro del ejido urbano. El índice de similitud entre zonas geográficas fue mayor para el par Este-Oeste (94.7), mientras que el menor fue para el par Sur-Oeste (33.3). Bufo arenarum fue la especie presente en todos los ambientes caracterizados, mientras que Hyla andina y Odontophrynus americanus son las especies con distribución más restringida y por lo tanto más vulnerables. Con los datos obtenidos, se generó un mapa de distribución potencial de las especies en la ciudad analizando las posibles causas de las diferencias observadas

[Anuran fauna from Salta city, Argentina]. / Fauna de anuros en la ciudad de Salta, Argentina.

The loss and transformation of habitat by anthropogenic activities is one of the main causes of biodiversity decrease. Amphibians are declining all over the world and one of the causes of this decline is thought to be habitat reduction. However, there are anuran populations in highly disturbed habitats, like cities. This study presents the ecological baseline needed to understand anuran communities in urban environments, for Salta City. Argentina (ca. 502,000 inhabitants). The sample was stratified by environments defined by infrastructure and geographic location. The species were identified by visual encounter techniques and by auditory transect during the 2002-2003 reproductive period. Three families, seven genera and twelve species were recorded and the species richness decreased from city border to center. Similarity index values among geographic areas was higher East-West (94.7) than South-West (33.3). Bufo arenarum was the only species recorded in all environments. Hyla andina and Odontophrynus americanus had a restricted distribution and are here considered vulnerable. The border effect can explain some distribution pattern in these populations. A map of the potential distribution of recorded species for Salta is provided.