Targeted ToF-SIMS Analysis of Macrophage Content from a Human Cranial Triphasic Calcium Phosphate Implant

Macrophages play a key role in determining the fate of implanted biomaterials, especially for biomaterials such as calcium phosphates (CaPs) where these cells play a vital role in material resorption and osteogenesis, as shown in different models, including clinical samples. Although substantial consideration is given to the design and validation of different CaPs, relatively little is known about their material-cell interaction. Specifically, the intracellular content of different CaP phases remains to be assessed, even though CaP-filled macrophages have been observed in several studies. In this study, 2D/3D ToF-SIMS imaging and multivariate analysis were directly applied on the histology samples of an explant to reveal the content of macrophages. The cellular content of the macrophages was analyzed to distinguish three CaP phases, monetite, beta-tricalcium phosphate, and pyrophosphate, which are all part of the monetite-based CaP implant composition under study. ToF-SIMS combined with histology revealed that the content of the identified macrophages was most similar to that of the pyrophosphate phase. This study is the first to uncover distinct CaP phases in macrophages from a human multiphasic CaP explant by targeted direct cell content analysis. The uncovering of pyrophosphate as the main phase found inside the macrophages is of great importance to understand the impact of the selected material in the process of biomaterial-instructed osteogenesis

Identidad étnica y redes personales entre jóvenes de Sarajevo

After fieldwork conducted among young people in Sarajevo, we found a relation between the discourses sustained by them and the ethnic categories they use to classify people and to identify themselves. Also we have found that people self-affiliated as "Bosnians" play an important role in the network of multiethnic relationships, in which strong ties, surprisingly, are still very important. Finally we found a relationship between the composition of personal networks and the ethnic discourses that are maintained.Después de un trabajo de campo realizado con un grupo de jóvenes en Sarajevo, hemos constatado la existencia de una relación entre los discursos que sostienen y las categorías étnicas que utilizan tanto para clasificar a los demás como para auto-identificarse. Asimismo hemos encontrado que los jóvenes que se autodenominan "Bosnios" juegan un rol importante en la red de relaciones multiétnicas, en la que los lazos fuertes, sorprendentemente, son muy importantes. Finalmente hemos hallado una relación entre la composición de las redes personales y los discursos étnicos que se sostienen. Vivimos, o creemos vivir, en múltiples "comunidades", imaginadas o no. Al mismo tiempo, el individuo y no el lugar, la familia o el grupo, se sitúa en el centro de la vida social y de las comunicaciones (Cf. Wellman, 2001). En este contexto, inducido por el avance del capitalismo flexible (Castells, 1996), pensamos que para entender adecuadamente la identidad o identidades postuladas por los individuos es necesario estudiar las redes personales y su dinámica. Desde esta perspectiva no podemos hablar de "etnias" o "multietnicidad" sin más precisiones, pues son conceptos basados en una concepción esencialista y estática de la identidad individual. El concepto de "sociedad multiétnica" es utilizado de una manera engañosamente progresista y objetiva, pues lo que en realidad legitima es la existencia de diferencias esenciales entre personas, alejando en lugar de acercar. Sin embargo, somos plenamente conscientes que los discursos esencialistas de la identidad étnica son omnipresentes, con enormes efectos políticos e individuales. Que planteemos que la concepción esencialista de la identidad sea inapropiada desde un punto de vista académico, no significa que ésta no se utilice políticamente y por lo tanto tenga consecuencias formidables en las relaciones sociales. Precisamente el estudio de las redes personales nos permite situarnos en una perspectiva que no utiliza con pretensiones analíticas conceptos "folk", como son los de "etnia", "pueblo" o "nación", sino que los sitúa en el terreno de los discursos sustentados por los actores (y los estados y medios de comunicación) y nos permite contextualizarlos mediante conceptos etic, es decir, impuestos por los investigadores. Sólo así podemos superar las tautologías que abundan en los discursos étnicos

Assumption without representation: the unacknowledged abstraction from communities and social goods

We have not clearly acknowledged the abstraction from unpriceable “social goods” (derived from communities) which, different from private and public goods, simply disappear if it is attempted to market them. Separability from markets and economics has not been argued, much less established. Acknowledging communities would reinforce rather than undermine them, and thus facilitate the production of social goods. But it would also help economics by facilitating our understanding of – and response to – financial crises as well as environmental destruction and many social problems, and by reducing the alienation from economics often felt by students and the public

Patient-Specific Titanium-Reinforced Calcium Phosphate Implant for the Repair and Healing of Complex Cranial Defects

BACKGROUND: The reconstruction of complex cranial defects is challenging and is associated with a high complication rate. The development of a patient-specific, titanium-reinforced, calcium phosphate-based (CaP-Ti) implant with bone regenerative properties has previously been described in 2 case studies with the hypothesis that the implant may improve clinical outcome. OBJECTIVE: To identify whether the introduction of CaP-Ti implant has the potential to improve clinical outcome. METHODS: A retrospective review of all patients having undergone CaP-Ti cranioplasty was conducted. Comprehensive clinical data were collected from the hospital computer database and patient records. Bone formation and osseointegration were analyzed in a single retrieval specimen. RESULTS: Fifty patients, with 52 cranial defects, met the inclusion criteria. The patient cohort displayed a previous failure rate of 64% (32/50) with autologous bone, alloplastic materials, or both. At a median follow-up time of 25 months, the explantation rate due to either early postoperative infection or persistent wound dehiscence was 1.9% (1/53) or 3.8% (2/53), respectively. Surgical intervention with local wound revision was required in 2 patients without the need of implant removal. One patient had a brain tumor recurrence, and the implant was explanted 31 months after implantation. Histologic examination showed that the entire implant was partly yet evenly transformed into vascularized compact bone. CONCLUSION: In the present study the CaP-Ti implant appears to have improved the clinical outcomes in a cohort of patients with a high rate of previous cranioplasty failures. The bone regenerative effect may in particular have an impact on the long-term success rate of the implant

Titanium reinforced calcium phosphate improves bone formation and osteointegration in ovine calvaria defects : a comparative 52 weeks study

In a 52 week ovine calvaria implantation model, the restoration of cranial defects with a bare titanium mesh (Ti-mesh) and a titanium mesh embedded in a calcium phosphate (CaP-Ti) were evaluated in seven animals. During the study, no major clinical abnormalities were observed, and all sheep presented a normal neurologic assessment. Blood and cerebrospinal fluid analysis, made at termination, did not show any abnormalities. No indentation of the soft tissue was observed for either test article; however, the Ti-mesh burr-hole covers were associated with filling of the calvarial defect by fibrous tissue mainly. Some bone formation was observed at the bottom of the created defect, but no significant bone was formed in the proximity of the implant. The defect sites implanted with CaP-Ti were characterized by a moderate degradation of the calcium phosphate (CaP) that was replaced by mature bone tissue. Calcium-phosphate-filled macrophages were observed in all animals, indicating that they might play a vital role in osteogenesis. The newly formed bone was present, especially at the bony edges of the defect and on the dura side. Integration of the Ti-mesh in a CaP improved bone formation and osteointegration in comparison to a bare Ti-mesh