Nanostructured fibrin-based hydrogel membranes for use as an augmentation strategy in Achilles tendon surgical repair in rats.

Hydrogels are polymeric biomaterials characterised by their promising biological and biomechanical properties, which make them potential alternatives for use in tendon repair. The aim of the present study was to generate in vitro, and determine the therapeutic efficacy in vivo, of novel nanostructured fibrin-based hydrogels to be used as an augmentation strategy for the surgical repair of rat Achilles tendon injuries. Fibrin, fibrin-agarose and fibrin-collagen nanostructured hydrogels (NFH, NFAH and NFCH, respectively) were generated and their biomechanical properties and cell-biomaterial interactions characterised ex vivo. Achilles tendon ruptures were created in 24 adult Wistar rats, which were next treated with direct repair (control group) or direct repair augmented with the generated biomaterials (6 rats/group). After 4 and 8 weeks, the animals were euthanised for macroscopical and histological analyses. Biomechanical characterisation showed optimal properties of the biomaterials for use in tendon repair. Moreover, biological analyses confirmed that tendon-derived fibroblasts were able to adhere to the surface of the generated biomaterials, with high levels of viability and functionality. In vivo studies demonstrated successful tendon repair in all groups. Lastly, histological analyses disclosed better tissue and extracellular matrix organisation and alignment with biomaterial-based augmentation strategies than direct repair, especially when NFAH and NFCH were used. The present study demonstrated that nanostructured fibrin-collagen hydrogels can be used to enhance the healing process in the surgical repair of tendon ruptures.

[Vegetative states: a syndrome in search of a new name]. / Estados vegetativos? Síndrome en busca de un nuevo nombre.

OBJECTIVES: 1. To critically analyze the concept of 'vegetative' state and a number of reasons that seem to justify the abandonment of this term. 2. To propose a new conceptual approach to the syndrome and, based on this approach, a new terminology. DEVELOPMENT: The concept of 'vegetative' state became popular in the medical literature, in the context of a 'neocorticalist' theory of consciousness. Its clear-cut simplicity and the prestige of its proponents contributed to this acceptance. However, this concept seems to be neurologically and philosophically inappropriate. In addition, in recent years a number of studies have shown that these states are frequently misdiagnosed, due mainly to their inherent complexity. Thus, the need for a new name for this syndrome has become increasingly evident. A conceptualization of the brain global functioning leads to a redefinition of these states. The 'syndrome of brain dismetafunction' is conceptually defined. This term does not have a pejorative connotation. It respects the inherent uncertainty associated to the subjective dimension of consciousness as well as to the prognosis of these states. It promotes an integrative approach to problems related to the diagnosis, treatment, and rehabilitation of these patients. CONCLUSION: It seems pertinent to propose the abandonment of the term 'vegetative' both as conceptually equivocal and as a term that may become a self-fulfilling prophecy. Moreover, a no less important reason to abandon this qualifier is the possibility of a more coherent conceptualization of this syndrome. As a consequence, this approach leads to a new terminology.

[A complete and precise reformulation of human death]. / Una reformulación completa y precisa de la muerte humana.

INTRODUCTION: Today, a very active debate exists about the concept and determination of death. The lack of both an integrating rationale and a consistent and precise formulation to approach such a fundamental issue has been notable. However, a contribution regarding both aspects is indispensable to overcome inconsistencies affecting current death concepts. DEVELOPMENT: It is argued in this article why a sufficiently defined 'consciousness-organism-as-a-whole' system and its critical metafunction determines the neurological standard for a complete and precise reformulation of human death. This metafunction cannot be reduced to any of the particular functions of the system. It characterizes the highest hierarchical level of qualitative organization in the human organism. It defines the criticality of the system and the ontological level pertinent to the definition of death. Human death is 'both the irreversible loss of consciousness (considering its three anatomical and physiological components), and, inherently and inseparably, the loss of the capacity of the organism to function as a whole'. CONCLUSIONS: It is argued why the rationale supporting this definition overcomes the problems posed by either currently accepted conceptions or by those competing to gain acceptance. Some of the implications of this re-approach in the intersection of neurology with other disciplines are considered.