Establishment of an inferior vena cava filter database and interventional radiology led follow-up - retrieval rates and patients lost to follow-up.

INTRODUCTION: To evaluate the rates of inferior vena cava (IVC) filter retrieval and the number of patient's lost to follow-up, before and after the establishment of an IVC filter database and interventional radiology (inserting physician) led follow-up. METHODS: On the 1st of June 2012, an electronic interventional radiology database was established at our Institution. In addition, the interventional radiology team took responsibility for follow-up of IVC filters. Data were prospectively collected from the database for all patients who had an IVC filter inserted between the 1st June 2012 and the 31st May 2014. Data on patients who had an IVC filter inserted between the 1st of June 2009 to the 31st of May 2012 were retrospectively reviewed. Patient demographics, insertion indications, filter types, retrieval status, documented retrieval decisions, time in situ, trackable events and complications were obtained in the pre-database (n = 136) and post-database (n = 118) cohorts. RESULTS: Attempted IVC filter retrieval rates were improved from 52.9% to 72.9% (P = 0.001) following the establishment of the database. The number of patients with no documented decision (lost to follow-up) regarding their IVC filter reduced from 31 of 136 (23%) to 0 of 118 patients (P = < 0.001). There was a non-significant reduction in IVC filter dwell time in the post-database group (113 as compared to 137 days, P = 0.129). CONCLUSION: Following the establishment of an IVC filter database and interventional radiology led follow-up, we demonstrate a significant improvement in the attempted retrieval rates of IVC filters and the number of patient's lost to follow-up.

Variability and degradation of homeostasis in self-sustained oscillators.

Homeostasis is known to be absolutely critical to the sustainability of living organisms. At the heart of homeostasis are various feedback loops, which can control and regulate a system to stay in a most favourable stable state upon the influence of various disturbance. While variability has emerged as a key factor in sustainability, too much variability could however be detrimental. It is thus absolutely crucial to understand the effect of fluctuation in different feedback loops. While modelling technique has achieved a great advancement to understand this issue, too a complicated model however often prevents us from disentangling different many processes. Here, we propose a novel model to gain a key insight into the effect of variability in feedback on self-sustained oscillation. Specifically, by taking into account variation in model parameters for self-excitation and nonlinear damping, corresponding to positive and negative feedback, respectively, we show how fluctuation in positive or negative feedback weakens the efficiency of feedback and affects self-sustained oscillations, possibly leading to a complete breakdown of self-regulation. While results are generic and could be applied to different self-regulating systems (e.g. self-regulation of neuron activity, normal cell growth, etc.), we present a specific application to heart dynamics. In particular, we show that fluctuation in positive feedback can lead to slow heart by either amplitude death or oscillation death pathway while fluctuation in negative feedback can lead to fast heart beat.

Embryonic-derived olfactory ensheathing cells remyelinate focal areas of spinal cord demyelination more efficiently than neonatal or adult-derived cells.

Transplanted olfactory ensheathing cells (OECs) contribute to functional recovery in a range of CNS injuries by several mechanisms, one of which is potentially their ability to form myelin sheaths. OECs sourced from donors of different ages have been shown to remyelinate in several in vitro and in vivo models. However, the optimal donor age for OEC associated remyelination is unclear. This project directly compared the remyelinating potential of p75 purified OEC transplants from three donor ages. OECs were sourced from the olfactory bulbs of embryonic, neonatal, and adult rats and purified by immunopanning, and their remyelinating potential was directly compared by transplantation into the same adult rat toxin-induced model of spinal cord demyelination. Remyelination efficiency 3 weeks after transplantation was assessed morphologically and by immunostaining. Our results indicate that all donor ages remyelinate; however, this process is most efficiently achieved by embryonic-derived OECs.