Novel and effective hemostats based on graphene oxide-polymer aerogels: In vitro and in vivo evaluation.

In this study, graphene oxide (GO)-based aerogels cross-linked with chitosan (CS), gelatin (GEL), and polyvinyl alcohol (PVA) were characterized and their hemostatic efficiencies both in vitro and in vivo were investigated and compared to commercial materials (ChitoGauze®XR and Spongostan™). All aerogels exhibited highly porous structures and a negative surface charge density favorable to their interaction with blood cells. The in vitro studies showed that all aerogels coagulated >60 % of the blood contained in their structures after 240 s of the whole-blood clotting assay, the GO-CS aerogel being the one with the highest blood clotting. All aerogels showed high hemocompatibility, with hemolytic rates <5 %, indicating their use as biomaterials. Among them, the GO-GEL aerogel exhibited the lowest hemolytic activity, due possibly to its high GEL content compared to the GO amount. According to their blood clotting activity, aerogels did not promote coagulation through extrinsic and intrinsic pathways. However, their surfaces are suitable for accelerating hemostasis by promoting alternative routes. All aerogels adhered platelets and gathered RBCs on their surfaces, and in addition the GO-CS aerogel surface also promoted the formation of filamentous fibrin networks adhered on its structure. Furthermore, in vivo evaluations revealed that all aerogels significantly shortened the hemostatic times and reduced the blood loss amounts compared both to the Spongostan™ and ChitoGauze®XR commercial materials and to the gauze sponge (control group). The hemostatic performance in vitro and in vivo of these aerogels suggests that they could be used as hemostats for controlling profuse bleedings.

Variability of empathy among dental students. Implications not yet understood in Latin America / Variabilidad empática en estudiantes de odontología. Consecuencias aún no entendidas en América Latina

Abstract Introduction: Empathy is a quality that allows dentists to build an intersubjective relationship with their patients, which, among other benefits, contributes to the effectiveness of the treatment. Objective: To determine whether there is variability in empathy levels between two populations of dental students and to describe theoretically the general implications of this variability for intervention strategies. Materials and methods: Exploratory cross-sectional study. The study population consisted of 1st-5th year dental students from the Universidad Santiago de Cali, Colombia (n=610; N=647) and the Universidad San Sebastián, Chile (n=535; N=800). In both groups, empathy was measured using the Jefferson Scale of Empathy (S-Version) Scale. Descriptive statistics (mean and standard deviation) were used for data analysis. Internal consistency of data was estimated using Cronbach's alpha and the intraclass correlation coefficient. A factorial analysis of variance was performed, and three factors were studied: University (U), Course (C), and Sex (S). The statistical significance level used was α≤ 0.05 and β ≤0.20. Results: Differences in empathy level and in some of its three dimensions were observed between students from both universities and among courses (lst-5th year). No differences were found between sexes. Conclusions: There is variability in empathy levels among dental students from both universities. Thus, the implementation of specific empathy intervention strategies in each dental medicine program offered in Latin America is required to increase empathy levels in this population.

Resumen Introducción. La empatía es un atributo que permite a los odontólogos establecer una relación intersubjetiva con sus pacientes, lo que contribuye a un tratamiento exitoso, entre otros beneficios. Objetivo. Determinar si hay variabilidad en los niveles de empatía entre dos poblaciones de estudiantes de odontología y describir teóricamente las implicaciones generales de esta variabilidad en estrategias de intervención. Materiales y métodos. Estudio exploratorio transversal. La población de estudio consistió de estudiantes de odontología de 1er a 5to año de la Universidad Santiago de Cali, Colombia (n=610; N=647) y la Universidad San Sebastián, Chile (n=535; N=800). En ambos grupos, la empatía se midió con la Escala de Empatía Médica de Jefferson (Versión S). Para el análisis de los datos se utilizó estadística descriptiva (media y desviación estándar). La consistencia interna de los datos se estimó mediante el coeficiente alfa de Cronbach y el coeficiente de correlación intraclase. Se realizó un análisis de varianza factorial: tres factores estudiados: Universidad (U), Curso (C) y Sexo (S). El nivel de significancia estadística utilizado fue de α≤0.05 y β≤0.20. Resultados. Se observaron diferencias en el nivel de empatía y algunas de sus tres dimensiones entre los estudiantes de ambas universidades y entre los cursos (1er-5to año). No se observaron diferencias entre sexos. Conclusiones. Existe variabilidad en los niveles de empatía entre los estudiantes de ambas universidades. Para aumentar los niveles de empatía en esta población en Latinoamérica se requiere implementar estrategias específicas de intervención empática en cada programa de odontología ofrecido en la región.

Improved hemocompatibility for gelatin-graphene oxide composite aerogels reinforced with proanthocyanidins for wound dressing applications.

Aerogels based on gelatin and graphene oxide (GO) were synthesized by microwave-assisted reactions, incorporating grape skin extracts -high in proanthocyanidins (PAs)- to develop a hemostatic device with improved properties. The effects of incorporating PAs into the aerogels were investigated in relation to their physicochemical properties, absorption ability, clotting activity and cytotoxicity in human dermal fibroblast (HDF) cells. The aerogels presented highly resistant porous structures, capable of absorbing more than 50 times their weight when in contact with a phosphate saline solution (PBS) and fresh human blood. Interestingly, the addition of PAs increased the negative surface charges and the blood absorption ability of the aerogels, which may make them suitable for hemostasis. The incorporation of 5% and 10% (w/w) of extracts into the aerogels increased the total coagulated blood content by 36.6% and 24.5% compared with gelatin-GO aerogel, respectively. These improvements in the hemostatic properties of the aerogels were greater with the inclusion of 5% (w/w) of grape skin extracts into the aerogels. The aerogels were also able to adhere red blood cells onto their surfaces, which could favor the formation of stable fibrin networks to promote hemostasis. Their clotting activity suggested the activation of alternative routes based on complement coagulation systems. Finally, the aerogels were non-toxic for HDF cells and the PAs were successfully released from their matrices. Thus, gelatin-GO aerogels reinforced with PAs are promising as topical phytodrug delivery systems, with great potential for wound healing processes.

Synthesis and characterization of graphene oxide chitosan aerogels reinforced with flavan-3-ols as hemostatic agents.

The natural mechanisms of the body cannot control massive hemorrhaging, resulting in a requirement for hemostatic intervention. In this study, Graphene oxide and Chitosan aerogels reinforced with grape seed (SD) and skin (SK) extracts were developed for use as hemostatic agents by evaluating the influence of pH on their synthesis, and the amount of grape extract added on the physical and chemical properties of the aerogels. The material was evaluated by FTIR, XRD, Raman spectroscopy, DLS, uniaxial compression tests and SEM. The capacity of the aerogels to absorb water, PBS and blood, as well as their coagulation capacity, were determined. In addition, the release profile for grape extracts in PBS and the material's cytotoxicity were determined. The aerogels that were synthesized under basic conditions and loaded with grape extracts were more rigid and negatively charged, and they presented smaller pores than the un-loaded acidic aerogels. For all aerogels, the hemoglobin absorption was greater than 90 % in the first 30 s. A higher density of adsorbed blood cells was observed on aerogels loaded with a higher amount of grape extract. The maximum release of extract from the aerogels occurred for those loaded with SK extracts at a basic pH; the aerogels that were prepared under acidic conditions dissolved in the media. Aerogels loaded with SK extracts under alkaline conditions were not cytotoxic toward human dermal fibroblasts and exhibited cell viabilities above 90 %. These findings suggest that these aerogels have the potential for use as hemostatic agents in wound management.