The small GTPase RhoB regulates endocytic trafficking of receptor tyrosine kinases (RTKs) and the non-receptor kinases Src and Akt. While receptor-mediated endocytosis is critical for signaling processes driving cell migration, mechanisms that coordinate endocytosis with the propagation of migratory signals remain relatively poorly understood. In this study, we show that RhoB is essential for activation and trafficking of the key migratory effectors Cdc42 and Rac in mediating the ability of platelet-derived growth factor (PDGF) to stimulate cell movement. Stimulation of the PDGF receptor-β on primary vascular smooth muscle cells (VSMCs) results in RhoB-dependent trafficking of endosome-bound Cdc42 from the perinuclear region to the cell periphery, where the RhoGEF Vav2 and Rac are also recruited to drive formation of circular dorsal and peripheral ruffles necessary for cell migration. Our findings identify a novel RhoB dependent endosomal trafficking pathway that integrates RTK endocytosis with Cdc42/Rac localization and cell movement. KeywordsRhoB; Cdc42; Rac; Endosome; platelet-derived growth factor receptor; endocytic trafficking; vascular smooth muscle cells; cell migration Cell migration is an important part of physiological and pathological processes that support embryonic morphogenesis, tissue repair/regeneration, immune surveillance, atherosclerosis, arthritis and cancer progression [Raftopoulou and Hall, 2004;Ridley et al., 2003]. Critical signaling events that promote cell migration are triggered by cell surface receptors resulting in fine alterations in the organization of the actin cytoskeleton. Among the many effector signaling molecules that alter actin organization, the Rho GTPases play pivotal roles in regulating cell migration. This class of molecules, which includes Cdc42, Rac and Rho, function as binary switches that trigger formation of different cytoskeletal actin structures required for migratory behaviors. Specifically, Cdc42, Rac and Rho promote the formation of filopodia, lamellipodia and stress fibers, respectively, different structures required to drive cell movement [Hall, 1998;Heasman and Ridley, 2008] Endocytosis of receptor tyrosine kinases (RTKs) such as the PDGFR not only promotes cell proliferation but also actin remodeling and cell migration. PDGFR promotes formation of migratory cellular protrusions, such as peripheral ruffles and circular dorsal ruffles by stimulating rearrangement of actin filaments [Andrae et al., 2008;Buccione et al., 2004]. As the major driving force in migration, the extension of leading edge lamellipodia formed by Rac activation serve as pliable and dynamic structures. As another necessary part of the actin dynamic at the leading edge, dorsal circular ruffles function as important sites in directing spatially restricted actin remodeling adjacent to lamellipodia extension [Buccione et al., 2004]. How receptor-mediated endocytosis regulates these processes remains elusive. It has been shown that the regulators of endocytosis, such as dynamin and R...

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Introduction Influenza vaccination of healthcare workers (HCW) has been recommended for over 30 years. In 2009, HCWs were designated as a priority group by the Centers for Disease and Prevention (CDC). Current HCW vaccination rates are 78% across all settings, and reach approximately 92% among those employed in hospital settings. Over the last decade, it has become clear that mandatory vaccine policies result in maximal rates of HCW immunization. Methods This observational 10-year study describes the implementation of a mandatory influenza vaccination policy in a dedicated quaternary pediatric hospital setting by a multidisciplinary team. We analyzed 10 years of available data from de-identified Occupational Health records from 2009-2010 through the 2018-2019 influenza seasons. Descriptive statistics were performed using Stata v15 and Excel. Results Sustained increases in HCW immunization rates above 99% were observed in the 10 years post implementation, in addition to a reduction in exemption requests and health-care associated influenza. In the year of implementation, 145 (1.6%) HCWs were placed on temporary suspension for failure to receive the vaccine without documentation of an exemption, with 9 (0.06%) subsequently being terminated. Since then, between 0-3 HCWs are terminated yearly for failure to receive the vaccine. Conclusion Implementation of our mandatory influenza vaccination program succeeded in successfully increasing the proportion of immunized HCWs at a quaternary care children’s hospital, reducing annual exemption requests with a small number of terminations secondary to vaccine refusal. Temporal trends suggest a positive impact on the safety of our patients.

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Background: Mandatory reporting of all healthcare-associated infections (HAIs) leads to substantial surveillance volume for infection prevention and control (IPC) programs. Prior to 2019, 6 infection preventionists were performing system-wide surveillance for all infection types using NHSN definitions at a large quaternary-care center in Pennsylvania. Limited surveillance validation was performed. With the continued expansion of the health system, increased demands for IPC expertise, and a growing team, the need for streamlined surveillance, and a validation program were identified. Methods: A surveillance training program for novice team members was developed and implemented. Infection prevention associates (IPAs), whose primary role was data management, began training. The new program included NHSN training videos, direct observation of surveillance with infection preventionists and practice case studies. Following training, IPAs performed surveillance for experienced infection preventionists covering high-risk inpatient units. To ensure high reliability, surveillance validation was initiated. Each month, ~10% of investigated infections were randomly pulled from the electronic surveillance system and divided among experienced infection preventionists. These validators performed unbiased reviews of the charts based on limited data, including patient demographics and culture results. Validation documentation included noting whether an infection was reportable to NHSN and a rationale. Data on whether or not each patient had a complex medical history and time spent validating each case were collected. Compliance of validator documentation aligning with original documentation was tracked. Discrepancies were discussed as a team and were adjudicated as needed. IPAs tracked hours spent on surveillance to capture effort transitioned from infection preventionists. Results: Between March and July 2019, an average of 223 (range, 178–261) potential infections were reviewed per month. From March through June 2019, 61 infections were selected for validation, with 98% compliance with original documentation. One minor discrepancy was attributed to interpretation of documentation in the medical record. Medical complexity accounted for 78% of reviews and validation time spent averaged 12 minutes per infection (range, 3–28 minutes). Self-reported effort directed from infection preventionists to 2 IPAs for surveillance was ~20 hours per week. An additional IPA was hired to perform surveillance in addition to other job responsibilities. Conclusions: Centralized surveillance programs can promote high reliability and cost-efficient IPC staffing for large healthcare systems, especially those with mandatory reporting requirements or medically complex patient populations. Improving surveillance skills among associate staff can increase experienced infection preventionist bandwidth for project management, staff supervision, and other leadership responsibilities. Lastly, validation programs are crucial to ensuring quality assurance of data reporting to both internal and external stakeholders.Funding: NoneDisclosures: None