Differential endothelial cell cycle status in postnatal retinal vessels revealed using a novel PIP-FUCCI reporter and zonation analysis.

Cell cycle regulation is critical to blood vessel formation and function, but how the endothelial cell cycle integrates with vascular regulation is not well-understood, and available dynamic cell cycle reporters do not precisely distinguish all cell cycle stage transitions in vivo. Here we characterized a recently developed improved cell cycle reporter (PIP-FUCCI) that precisely delineates S phase and the S/G2 transition. Live image analysis of primary endothelial cells revealed predicted temporal changes and well-defined stage transitions. A new inducible mouse cell cycle reporter allele was selectively expressed in postnatal retinal endothelial cells upon Cre-mediated activation and predicted endothelial cell cycle status. We developed a semi-automated zonation program to define endothelial cell cycle status in spatially defined and developmentally distinct retinal areas and found predicted cell cycle stage differences in arteries, veins, and remodeled and angiogenic capillaries. Surprisingly, the predicted dearth of S-phase proliferative tip cells relative to stalk cells at the vascular front was accompanied by an unexpected enrichment for endothelial tip and stalk cells in G2, suggesting G2 stalling as a contribution to tip-cell arrest and dynamics at the front. Thus, this improved reporter precisely defines endothelial cell cycle status in vivo and reveals novel G2 regulation that may contribute to unique aspects of blood vessel network expansion.

Differential endothelial cell cycle status in postnatal retinal vessels revealed using a novel PIP-FUCCI reporter and zonation analysis.

Cell cycle regulation is critical to blood vessel formation and function, but how the endothelial cell cycle integrates with vascular regulation is not well-understood, and available dynamic cell cycle reporters do not precisely distinguish all cell cycle stage transitions in vivo. Here we characterized a recently developed improved cell cycle reporter (PIP-FUCCI) that precisely delineates S phase and the S/G2 transition. Live image analysis of primary endothelial cells revealed predicted temporal changes and well-defined stage transitions. A new inducible mouse cell cycle reporter allele was selectively expressed in postnatal retinal endothelial cells upon Cre-mediated activation and predicted endothelial cell cycle status. We developed a semi-automated zonation program to define endothelial cell cycle status in spatially defined and developmentally distinct retinal areas and found predicted cell cycle stage differences in arteries, veins, and remodeled and angiogenic capillaries. Surprisingly, the predicted dearth of proliferative tip cells at the vascular front was accompanied by an unexpected enrichment for endothelial tip cells in G2, suggesting G2 stalling as a contribution to tip-cell arrest. Thus, this improved reporter precisely defines endothelial cell cycle status in vivo and reveals novel G2 regulation that may contribute to unique aspects of blood vessel network expansion.

Supporting the spread and scale-up of electronic consultation across Canada: cross-sectional analysis.

OBJECTIVE: To examine the process of implementing an electronic consultation (eConsult) service and evaluate its impact along key metrics outlined by the Reach, Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) framework. DESIGN: Cross-sectional study. SETTING: Clinics using eConsult in four provinces across Canada: Alberta, Manitoba, Quebec and Newfoundland and Labrador. PARTICIPANTS: All eConsult cases submitted in four participating provinces were included. INTERVENTION: The eConsult service is a secure online application that allows primary care providers and specialists to communicate regarding a patient's care. We measured the impact using system utilisation data and mandatory close-out surveys completed at the end of each eConsult. MAIN OUTCOME MEASURES: Implementation progress and impact were examined using the five categories outlined by the RE-AIM framework: reach, effectiveness, adoption, implementation and maintenance. RESULTS: Four provinces provided data from different periods, ranging from 4 years (Alberta) to 10 months (Manitoba). Total cases completed ranged from 96 (Manitoba) to 6885 (Alberta). Newfoundland had the largest menu of available specialties (n=35), while Alberta and Quebec had the smallest (n=22). The most frequently requested groups varied across provinces, with only endocrinology appearing in the top five for all provinces. The average specialist response time ranged from 3 days (Manitoba) to 16.7 days (Alberta). Between 54% (Newfoundland) and 66% (Manitoba) of cases resulted in new or additional information. Primary care providers avoided completing referrals they had originally considered in 36% (Newfoundland) to 53% of cases (Manitoba), while only between 27 % (Quebec) and 29% (Newfoundland) of cases resulted in a referral. In every province, services demonstrated higher rates of usage in their last quarter of data than their first. CONCLUSIONS: eConsult was successfully implemented in four new provinces across Canada. Implementation strategies and scope varied, but services demonstrated substantial consistency on several key metrics, most notably on whether new information was learnt and impact on decision to refer.