Mimicking nature by codelivery of stimulant and inhibitor to create temporally stable and spatially restricted angiogenic zones.

Nature frequently utilizes opposing factors to create a stable activator gradient to robustly control pattern formation. This study employs a biomimicry approach, by delivery of both angiogenic and antiangiogenic factors from spatially restricted zones of a synthetic polymer to achieve temporally stable and spatially restricted angiogenic zones in vivo. The simultaneous release of the two spatially separated agents leads to a spatially sharp angiogenic region that is sustained over 3 wk. Further, the contradictory action of the two agents leads to a stable level of proangiogenic stimulation in this region, in spite of significant variations in the individual release rates over time. The resulting spatially restrictive and temporally sustained profiles of active signaling allow the creation of a spatially heterogeneous and functional vasculature.

How Good is Good Enough?: Current-Day Pediatric Residency Program Directors' Challenges in Assessing and Achieving Resident Procedural Competency.

OBJECTIVE: Significant gaps exist in the pediatric resident (PR) procedural experience. Graduating PRs are not achieving competency in the 13 ACGME recommended procedures. It is unclear why PR are not able to achieve competency, or how existing gaps may be addressed. METHODS: We performed in-depth one-on-one semistructured interviews with 12 pediatric residency program directors (PPDs). The interviews were audio-recorded, and transcribed verbatim. Coding of the data using conventional content analysis led to generation of categories, which were validated through consensus development. RESULTS: We identified 4 main categories, including (1) programs struggle to ensure adequate training in procedural skills for PRs, with various barriers reported; (2) programs develop individualized strategies to address challenges in procedural skills training, and multiple options are necessary; (3) PPDs face challenges defining procedural competency and standardizing expectations; and (4) expectations for PR procedural training may require modification based upon current practice environments. Solutions include simulation, procedural boot camps, and procedural/subspecialty electives. CONCLUSIONS: Numerous methods to combat challenges in PR procedural training have been identified by participating PPDs, including simulation, tailoring electives, and developing institutional guidelines. However, accreditation bodies may need to update procedural expectations based on individual resident career goals and realities of current day practice.

Statistical platform to discern spatial and temporal coordination of endothelial sprouting.

Many biological processes, including angiogenesis, involve intercellular feedback and temporal coordination, but inference of these relations is often drowned in low sample sizes or noisy population data. To address this issue, a methodology was developed to statistically study spatial lateral inhibition and temporal synchronization in one specific biological process, endothelial sprouting mediated by Notch signaling. Notch plays an essential role in the development of organized vasculature, but the effects of Notch on the temporal characteristics of angiogenesis are not well understood. Results from this study showed that Notch lateral inhibition operates at distances less than 31 µm. Furthermore, combining time lapse microscopy with an intraclass correlation model typically used to analyze family data showed intrinsic temporal synchronization among endothelial sprouts originating from the same microcarrier. Such synchronization was reduced with Notch inhibitors, but was enhanced with the addition of Notch ligands. These results indicate that Notch plays a critical role in the temporal regulation of angiogenesis, as well as spatial control, and this method of analysis will be of significant utility in studies of a variety of other biological processes.