Fiber reinforced hydrated networks recapitulate the poroelastic mechanics of articular cartilage

The role of poroelasticity on the functional performance of articular cartilage has been established in the scientific literature since the 1960s. Despite the extensive knowledge on this topic there remain few attempts to design for poroelasticity and to our knowledge no demonstration of an engineered poroelastic material that approaches the physiological performance. In this paper, we report on the development of an engineered material that begins to approach physiological poroelasticity. We quantify poroelasticity using the fluid load fraction, apply mixture theory to model the material system, and determine cytocompatibility using primary human mesenchymal stem cells. The design approach is based on a fiber reinforced hydrated network and uses routine fabrication methods (electrohydrodynamic deposition) and materials (poly[ɛ-caprolactone] and gelatin) to develop the engineered poroelastic material. This composite material achieved a mean peak fluid load fraction of 68%, displayed consistency with mixture theory, and demonstrated cytocompatibility. This work creates a foundation for designing poroelastic cartilage implants and developing scaffold systems to study chondrocyte mechanobiology and tissue engineering. STATEMENT OF SIGNIFICANCE: Poroelasticity drives the functional mechanics of articular cartilage (load bearing and lubrication). In this work we develop the design rationale and approach to produce a poroelastic material, known as a fiber reinforced hydrated network (FiHy™), that begins to approach the native performance of articular cartilage. This is the first engineered material system capable of exceeding isotropic linear poroelastic theory. The framework developed here enables fundamental studies of poroelasticity and the development of translational materials for cartilage repair.

Analysis of relation between coronary perfusion pressure and the extracted parameters from a ventricular fibrillation ECG signal

This work presents an alternative return of spontaneous circulation (ROSC) estimate using indirectly induced presumption that coronary perfusion pressure (CPP) correlates with the extracted parameter from the ventricular fibrillation (VF) ECG signal. In past studies, it is revealed that successful cardiopulmonary resuscitation (CPR) needs at least 30 approximately 40 mmHg CPP during the aortic diastolic period. In 360 segments derived from 18 test dogs with experimental cardiac arrest of cardiac cause, we analyzed the ability of 4 spectral features of VF before countershock to discriminate or not between segments that correspond to CPP. The median frequency (MF), peak frequency (PF), average segment amplitude (ASA) and maximum segment amplitude (MSA) were studied. After preprocessing the raw data acquired from the specific experimental setup and protocol, we verified CPP is a serious estimate of ROSC, and then we analyzed the extracted parameters corresponding to CPP by multiple regression. In the specific conditional frequency domain (MF: 9.42 approximately 12.42 Hz, PF: 8.71 approximately 13.08 Hz, ASA: > 0.19 mV), CPP is correlated to the extracted parameter with 0.71 +/- 0.05 coefficient of multiple determination (R(2)). The combination of MF, PF, and ASA achieved a 79.47 +/- 3% sensitivity and 41.67 +/- 4% specificity in testing.