Finite element analysis of the influence of cyclic strain on cells anchored to substrates with varying properties.

The response of cytoskeleton to mechanical cues plays a pivotal role in understanding several aspects of cellular growth, migration, and cell-cell and cell-matrix interactions under normal and diseased conditions. Finite element analysis (FEA) has become a powerful computational technique to study the response of cytoskeleton in the maintenance of overall cellular mechanics. With the revelation of role of external mechanical microenvironment on cell mechanics, FEA models have also been developed to simulate the effect of substrate stiffness on the mechanical properties of cancer cells. However, the models developed so far model cellular response under static mode, whereas in physiological condition, cells always experience dynamic loading conditions. To develop a more accurate model of cell-extracellular matrix (ECM) interactions, this paper models the cytoskeleton and other parts of the cell by beam and solid elements respectively, assuming spherical morphology of the cell. The stiffness and roughness of extracellular matrix were varied. Furthermore, static and dynamic sinusoidal loads were applied through a flat plate indenter on the cell along with providing sinusoidal strain at the substrate. It is observed that due to axial loading, cell reaches a plastic region, and when the sinusoidal loading is added to the axial load, the cell experiences permanent deformation. Degradation of the cytoskeleton elements and a physiologically more relevant spherical cap shape of the cell were also considered during the analysis. This study suggests that asperity topology of the substrate and indirect cyclic load can play a significant role in the shape alterations and motion of a cell.

Establishing a deceased donor program in north Indian region: lessons learnt.

INTRODUCTION: Living-related donors are the source of almost all organ transplants in India. However, these donations fall far short of current needs, and there remains a huge disparity between demand and supply of organs. In the last five yr, a consistent increase in deceased donor transplant activity has been observed in some southern Indian states. This report describes our experience of establishing a new deceased donor program in the state of Uttar Pradesh in north India. METHODS: We describe our experience on counseling families of all brain-dead patients admitted to our center from October 2013 to September 2014 and data on retrieving and transplanting organs. RESULTS: A total of 99 brain-dead patients were identified, of which 67 were medically eligible as donors. Fourteen patients developed cardiac arrest before the counseling could begin. Only eight families agreed for multi-organ donation. CONCLUSION: Lack of consensus among the family members, mistrust of the medical system, fear of mutilation of the body, and delay in the funeral were identified as the main reasons behind negative consent. Conversely, mass media campaign, proper ICU care of brain-dead patients, rapport with the family and streamlining all medico legal processes were associated with positive consent.