[Creation and functioning of Covid-19 pre-hospital triage centres : experience of french-speaking GP-coordinators]. / Face à la COVID-19. Création et fonctionnement des centres de tri pré-hospitaliers : expérience des médecins généralistes coordinateurs francophones.

Pre-hospital triage centres were created during the first wave of Covid-19 in March 2020. The intention was to examine patients in appropriate sanitary conditions and prevent emergency departments from overcrowding. This study describes triage centres in the Federation Wallonia-Brussels. The aim of the study was to collect key aspects of triage centres, implementation and information about the daily functioning interpreted positively or negatively by the GP-coordinators in charge of their management. This study was divided into two parts : an online questionnaire and semi-structured interviews. Overall, 14 questionnaires and 6 interviews were collected among the 44 initially contacted GP-coordinators. Our results point to a highly heterogeneous organisation of the triage centres, nevertheless adapted to local contexts, as well as a gap between local effective dynamics and challenges regarding federal/regional cooperation. This study may help for further crisis management plans.

Lors de la première vague de l'épidémie COVID-19, en mars 2020, des centres de tri (CDT) pré-hospitaliers ont été créés. Leur objectif était double : examiner les patients dans les conditions sanitaires adéquates et limiter l'afflux de patients aux urgences. L'étude vise à décrire ces CDT en Fédération Wallonie-Bruxelles. L'objectif était de relever, auprès des médecins généralistes (MG) coordinateurs de ces centres, les éléments ressentis comme positifs et négatifs dans la mise en place et le fonctionnement quotidien des CDT afin d'améliorer le dispositif pour de futures implémentations. Cette étude comportait deux volets : un questionnaire en ligne et des entretiens semi-structurés. Sur les 44 MG coordinateurs contactés, 14 questionnaires et 6 entretiens ont été récoltés. Nous avons mis en évidence une organisation très hétérogène des CDT, adaptée au contexte local, ainsi qu'un décalage entre la dynamique locale, décrite comme efficace, et les difficultés de coopération avec les niveaux fédéral et régional. Les résultats de cette étude pourraient aider dans l'implémentation de prochains plans de prise en charge en période de crise sanitaire.

Structure and function of RGD peptides involved in bone biology.

This review focuses on recent papers that describe the involvement of the RGD sequence in bone biology and incorporate the use of synthetic RGD peptides to develop new drugs or control the bioactivity of materials used for bone regeneration. Because in vivo bone function is completely dependent on angiogenesis and vessels, the present publication is focused on physiology, pathophysiology and therapeutics of RGD peptides dedicated to bone cells and endothelial systems. It appears that alphavbeta3, alphavbeta5 and alphaIIbbeta3 are the integrins most reported to be involved in bone function and RGD sequence binding. The specificity of RGD peptides depends on backbone conformation, orientations of the charged side chains of Arg and Asp residues, and hydrophobic moieties flanking the Asp residue. Despite of recent progress in integrins and RGD peptide structures and function, future work should focus on integrin selectivity of RGD-based agents, model structure and activity-selectivity relationships.

Surface coating with cyclic RGD peptides stimulates osteoblast adhesion and proliferation as well as bone formation.

The physiological inertness of synthetic implant materials often results in insufficient implant integration and limited acceptance of implants in tissues. After implantation the implant surface is often separated from the surrounding healthy and regenerating tissue, for example by a fibrous capsule. To avoid this host-versus-graft reaction, a strong mechanical contact between tissue and implant must be ensured. An enhanced contact between graft and the surrounding tissue can be provided by coating the implant with cell-adhesive molecules. The highly active and alpha(v)beta(3)- and alpha(v)beta(5)-integrin-selective peptide c(-RGDfK-) (f=D-phenylalanine) was functionalized with various linker molecules containing an acrylamide end group by using the lysine side chain of c(-RGDfK-). The acrylamide group can be used to bind the peptide covalently to poly(methyl methacrylate) (PMMA) surfaces. The coated surfaces effectively bind to murine osteoblasts as well as human osteoblasts in vitro when a minimum distance of 3.5 nm between surface and the constrained RGD sequence is provided. In contrast to osteoblasts in cell suspension, surface-bound osteoblasts show no apoptosis but proliferate by a factor of 10 over a 22 d period. Coating of inert implant surfaces with highly active and alpha(v)-selective peptides affords a marked improvement in osteoblast binding over current technologies. In vivo studies show that peptide-coated PMMA pellets implanted into the patella groove of rabbits are integrated into the regenerating bone tissue faster and more strongly than uncoated pellets.

Induced tissue integration of bone implants by coating with bone selective RGD-peptides in vitro and in vivo studies.

The optimal function of medical implant materials used in tissue substitution is often limited due to its healing properties. This effect is linked to reduced interactions of the implants with the surrounding tissue. Implant surfaces biologically functionalized with arginine-glycine-aspartic acid (RGD) peptides, a class of cellular adhesion factors, are described in this paper. The RGD-peptides are either bound via bovine serum albumin linking on culture plastic dishes as a model surface or via acrylic acid coupling on PMMA surface as a potential implant material. Resulting functionalized surfaces aquire the capability to bind cultured osteoblasts in high levels and show high proliferation rates in vitro. These results are observed for osteoblast cultures as well as from different species with different preparation procedures. A critical minimum distance between the bioactive portion of the RGD-peptides and the implant surface of 3.0-3.5 nm is crucial for the induction of an optimum cell binding process. In vivo animal studies in the rabbit show that newly formed bone tissue generated a direct contact with the RGD-peptide coated implants. In contrast uncoated implants are separated from newly formed bone tissue by a fibrous tissue layer thereby preventing the formation of a direct implant-bone bonding.