Investigating neovascularization in rat decellularized intestine - an in vitro platform for studying angiogenesis

One of the main challenges currently faced by tissue engineers is the loss of tissues post implantation due to delayed neovascularization. Several strategies are under investigation to create vascularized tissue but none have yet overcome this problem. In this study we produced a decellularized natural vascular scaffold from rat intestine to use as an in vitro platform for neovascularization studies for tissue engineered constructs. Decellularization resulted in almost complete (97%) removal of nuclei and DNA, while collagen, glycosaminoglycans and laminin content was preserved. Decellularization did, however, result in the loss of elastin and fibronectin. Some proangiogenic factors were retained, as fragments of decellularized intestine were able to stimulate angiogenesis in the chick chorioallantoic membrane assay. We demonstrated that decellularization left perfusable vascular channels intact, and these could be repopulated with human dermal microvascular endothelial cells. Optimization of reendothelialisation of the vascular channels showed this was improved by continuous perfusion of the vasculature and further improved by infusion of human dermal fibroblasts into the intestinal lumen, from where they invaded into the decellularized tissue. Finally we explored the ability of the perfused cells to form new vessels. In the absence of exogenous angiogenic stimuli, Dll4, a marker of endothelial capillary-tip cell activation during sprouting angiogenesis was absent, indicating the reformed vasculature was largely quiescent. However, after addition of VEGFA, Dll4 positive endothelial cells could be detected, demonstrating this engineered vascular construct maintained its capacity for neovascularization. In summary we have demonstrated how a natural xenobiotic vasculature can be used as an in vitro model platform to study 3 neovascularization and provide information on factors that are critical for efficient reendothelialisation of decellularized tissue

Collaborating for Success! Building a Digital Learning Object Repository

At the Florida State College at Jacksonville, the Library and the Center for e-Learning collaborated to build a searchable repository of digital learning objects for faculty to easily locate and upload into their courses. In this program, the presenters will address how to create instructional information for online students in a format that is understandable, usable and accessible. Additionally, they will outline the way they developed an authoritative system of tagging and organizing these resources

Fabrication of biodegradable synthetic vascular networks and their use as a model of angiogenesis

One of the greatest challenges currently faced in tissue engineering is the incorporation of vascular networks within tissue-engineered constructs. The aim of this study was to develop a technique for producing a perfusable, three-dimensional cell friendly model of vascular structures that could be used to study the factors affecting angiogenesis and vascular biology in engineered systems in more detail. Initially, biodegradable synthetic pseudo-vascular networks were produced via the combination of robocasting and electrospinning techniques. The internal surfaces of the vascular channels were then recellularized with human dermal microvascular endothelial cells (HDMECs) with and without the presence of human dermal fibroblasts (HDFs) on the outer surface of the scaffold. After 7 days in culture, channels that had been reseeded with HDMECs alone, demonstrated irregular cell coverage. However when using a co-culture of HDMECs inside and HDFs outside the vascular channels, coverage was found to be continuous throughout the internal channel. Using this cell combination, collagen gels loaded with vascular endothelial growth factor were deposited onto the outer surface of the scaffold and cultured for a further 7 days after which endothelial cell (EC) outgrowth from within the channels into the collagen gel was observed showing the engineered vasculature maintains its capacity for angiogenesis. Furthermore the HDMECs appeared to have formed perfusable tubules within the gel. These results show promising steps towards the development of an in vitro platform upon which to study angiogenesis and vascular biology in a tissue-engineering context

What topics of peer interactions correlate with student performance in physics courses?

Research suggests that interacting with more peers about physics course material is correlated with higher student performance. Some studies, however, have demonstrated that different topics of peer interactions may correlate with their performance in different ways, or possibly not at all. In this study, we probe both the peers with whom students interact about their physics course and the particular aspects of the course material about which they interacted in six different introductory physics courses: four lecture courses and two lab courses. Drawing on methods in social network analysis, we replicate prior work demonstrating that, on average, students who interact with more peers in their physics courses have higher final course grades. Expanding on this result, we find that students discuss a wide range of aspects of course material with their peers: concepts, small-group work, assessments, lecture, and homework. We observe that in the lecture courses, interacting with peers about concepts is most strongly correlated with final course grade, with smaller correlations also arising for small-group work and homework. In the lab courses, on the other hand, small-group work is the only interaction topic that significantly correlates with final course grade. We use these findings to discuss how course structures (e.g., grading schemes and weekly course schedules) may shape student interactions and add nuance to prior work by identifying how specific types of student interactions are associated (or not) with performance.Comment: Submitted to European Journal of Physic

Clinical trial of FK 506 immunosuppression in adult cardiac transplantation

The new immunosuppressive agent FK 506 was used as primary immunotherapy in conjunction with low-dose steroids and azathioprine in 72 patients subsequent to orthotopic cardiac transplantation. Overall patient survival at a mean follow-up of 360 days was 92%. The number of episodes of cardiac rejection (grade 3A or greater) within 90 days of transplantation was 0.95 per patient. The actuarial freedom from rejection at 90 days was 41%. Achievement of this level of immunosuppression is comparable with that of cyclosporine-based triple-drug therapy with OKT3 immunoprophylaxis. Thirty percent of patients were tapered off all steroids, and the average steroid dose in the group who received steroids was 8.6 mg of prednisone per day. The incidence of infection reflected the diminished necessity for steroids: seven major infections (10%) and 11 minor infections (16%). Renal dysfunction occurred during the perioperative period in most patients in this trial. However, the incidence of hypertension was 54% compared with 70% during the cyclosporine era. Ten adults underwent successful rescue therapy with FK 506 after cardiac rejection refractory to conventional immunotherapy. Side effects of FK 506 were notably few, and the results of the trial are encouraging for the future of the cardiac transplant recipient. © 1992

Towards understanding startup product development as effectual entrepreneurial behaviors

Software startups face with multiple technical and business challenges, which could make the startup journey longer, or even become a failure. Little is known about entrepreneurial decision making as a direct force to startup development outcome. In this study, we attempted to apply a behaviour theory of entrepreneurial firms to understand the root-cause of some software startup s challenges. Six common challenges related to prototyping and product development in twenty software startups were identified. We found the behaviour theory as a useful theoretical lens to explain the technical challenges. Software startups search for local optimal solutions, emphasise on short-run feedback rather than long-run strategies, which results in vague prototype planning, paradox of demonstration and evolving throw-away prototypes. The finding implies that effectual entrepreneurial processes might require a more suitable product development approach than the current state-of-practice.Comment: This is the author's version of the work. Copyright owner's version can be accessed at https://doi.org/10.1007/978-3-319-69191-6_15, 8th ICSOB 2017, Essen, German

Fast diffusion of a Lennard-Jones cluster on a crystalline surface

We present a Molecular Dynamics study of large Lennard-Jones clusters evolving on a crystalline surface. The static and the dynamic properties of the cluster are described. We find that large clusters can diffuse rapidly, as experimentally observed. The role of the mismatch between the lattice parameters of the cluster and the substrate is emphasized to explain the diffusion of the cluster. This diffusion can be described as a Brownian motion induced by the vibrationnal coupling to the substrate, a mechanism that has not been previously considered for cluster diffusion.Comment: latex, 5 pages with figure

Influence of nonlocal electrodynamics on the anisotropic vortex pinning in YNi2B2CYNi_2B_2C

We have studied the pinning force density Fp of YNi_2B_2C superconductors for various field orientations. We observe anisotropies both between the c-axis and the basal plane and within the plane, that cannot be explained by usual mass anisotropy. For magnetic field $H \parallel c$, the reorientation structural transition in the vortex lattice due to nonlocality, which occurs at a field $H_1 \sim 1kOe$, manifests itself as a kink in Fp(H). When $H \bot c$, Fp is much larger and has a quite different H dependence, indicating that other pinning mechanisms are present. In this case the signature of nonlocal effects is the presence of a fourfold periodicity of Fp within the basal plane.Comment: 4 pages, 3 figure