Faculty Bibliography

PURPOSE/OBJECTIVE:Chronic use of selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression has been linked to an imbalance in bone metabolism leading to osteoporosis. More recently, the use of SSRIs in murine models has been shown to delay bone healing both in vivo and in vitro by decreasing the osteoblastic differentiation and mineralization. The purpose of this study was to evaluate whether or not chronic use of SSRI's in nonunion patients increases their time to union after surgical intervention. METHODS:We retrospectively analyzed 343 patients in a nonunion database to determine which patients were on SSRI medication. Of these patients, 139 could be contacted and of those 102 were not taking SSRIs and 37 were taking SSRIs. Patient's time to union from nonunion surgical intervention between each cohort at our institution was recorded as the primary outcome. Patient's medical comorbidities that could affect union rates such as diabetes and smoking status were also noted. Baseline Short Musculoskeletal Function Assessment (SMFA) index for bother and function were recorded from the time of nonunion surgery as well as last follow-up. RESULTS:Compared to recent census data, we found significantly more patients in the nonunion cohort using SSRIs (26.6%) than patients in the general population using any type of antidepressant (11%). There was no significant difference in the patients' baseline characteristics other than patients on SSRI treatment had a higher body mass index (BMI) and age (p = 0.048 and p = 0.043, respectively). There was no significant difference noted in the fracture types (p = 0.2063). Patients on SSRIs had a higher SMFA bother index and function index on follow-up (p = 0.0103, p = 0.0147). Patients in the SSRI group had a mean time to union from nonunion surgery of 6.1 months compared to 6.0 in patients without SSRI usage (p = 0.74). These did not reach statistical significance when subcohort analysis for long bone fractures was performed for the femur, tibia, and humerus. CONCLUSION/CONCLUSIONS:To our knowledge, this is the first clinical study to investigate the effects of SSRIs on fracture healing. While in vivo and in vitro murine models have shown that SSRIs can have a deleterious effect on osteoblastic activity, our retrospective analysis did not show a significant difference in time to union between patients with chronic SSRI use and patients who have not been on SSRIs. However, this investigation did show a higher incidence of SSRI use in the nonunion cohort when compared to the general population. In the context of the recent animal model study, this may point to a negative effect of SSRI use on the acute fracture healing process.

Skin wounds in adult mammals typically heal with a fibrotic scar and fail to restore ectodermal appendages, such as hair follicles or adipose tissue. Intriguingly, new hair follicles regenerate in the center of large full-thickness wounds of mice in a process called wound-induced hair neogenesis (WIHN). WIHN is followed by neogenesis of dermal adipose tissue. Both neogenic events reactivate embryonic-like cellular and molecular programs. The WIHN model provides a platform for studying mammalian regeneration, and findings from this model could instruct future regenerative medicine interventions for treating wounds and alopecia. Since Ito et al. rediscovered WIHN 15 years ago, numerous investigators have worked on the WIHN model using varying wounding protocols and model interpretations. Because a variety of factors, including environmental variables and choice of mouse strains, can affect the outcomes of a WIHN study, the purpose of this article is to provide an overview of the experimental variables that impact WIHN so that experiments between laboratories can be compared in a meaningful manner.

Development, morphogenesis, immune system function, and cancer metastasis rely on the ability of cells to move through diverse tissues. To dissect migratory cell behavior in vivo, we developed cell type-specific imaging and perturbation techniques for Drosophila primordial germ cells (PGCs). We find that PGCs use global, retrograde cortical actin flows for orientation and propulsion during guided developmental homing. PGCs use RhoGEF2, a RhoA-specific RGS-RhoGEF, as a dose-dependent regulator of cortical flow through a feedback loop requiring its conserved PDZ and PH domains for membrane anchoring and local RhoA activation. This feedback loop is regulated for directional migration by RhoGEF2 availability and requires AMPK rather than canonical Gα_12/13 signaling. AMPK multisite phosphorylation of RhoGEF2 near a conserved EB1 microtubule-binding SxIP motif releases RhoGEF2 from microtubule-dependent inhibition. Thus, we establish the mechanism by which global cortical flow and polarized RhoA activation can be dynamically adapted during natural cell navigation in a changing environment.

The pectoral fins of teleost fish are analogous structures to human forelimbs, and the developmental mechanisms directing their initial growth and patterning are conserved between fish and tetrapods. The forelimb vasculature is crucial for limb function, and it appears to play important roles during development by promoting development of other limb structures, but the steps leading to its formation are poorly understood. In this study, we use high-resolution imaging to document the stepwise assembly of the zebrafish pectoral fin vasculature. We show that fin vascular network formation is a stereotyped, choreographed process that begins with the growth of an initial vascular loop around the pectoral fin. This loop connects to the dorsal aorta to initiate pectoral vascular circulation. Pectoral fin vascular development continues with concurrent formation of three elaborate vascular plexuses, one in the distal fin that develops into the fin-ray vasculature and two near the base of the fin in association with the developing fin musculature. Our findings detail a complex, yet highly choreographed, series of steps involved in the development of a complete, functional, organ-specific vascular network.

The cell envelope of Gram-negative bacteria is composed of an inner membrane, outer membane, and an intervening periplasmic space. How the outer membrane lipids are trafficked and assembled there, and how the asymmetry of the outer membrane is maintained is an area of intense research. The Mla system has been implicated in the maintenance of lipid asymmetry in the outer membrane, and is generally thought to drive the removal of mislocalized phospholipids from the outer membrane and their retrograde transport to the inner membrane. At the heart of the Mla pathway is a structurally unique ABC transporter complex in the inner membrane, called MlaFEDB. Recently, an explosion of cryo-EM studies has begun to shed light on the structure and lipid translocation mechanism of MlaFEDB, with many parallels to other ABC transporter families, including human ABCA and ABCG, as well as bacterial lipopolysaccharide and O-antigen transporters. Here we synthesize information from all available structures, and propose a model for lipid trafficking across the cell envelope by MlaFEDB.

Purpose: To compare outcomes following IVC stent placement covering versus not covering the renal veins
Material(s) and Method(s): Consecutive patients who underwent IVC stent placement for venous obstruction at a single quaternary care center between 1999 and 2018 were retrospectively identified. These 144 patients were divided into two cohorts based on imaging: 48 patients with an IVC stent implanted across the renal veins (covered) and 96 patients with an IVC stent sparing renal veins (uncovered). Baseline and post-procedural eGFR values were calculated using the CKD-EPI Creatinine Equation (2021)1. Baseline demographics and eGFR were compared between the two groups using Student's t-tests and chi² tests. Changes in average eGFR from baseline were calculated and differences between the cohorts were assessed using Student's t-tests. Kaplan-Meier methods were used to assess the primary patency of the stents in both groups. The covered and uncovered groups did not differ significantly on sex (P = 0.68), race (P = 0.12), age (P = 0.40), or underlying thrombophilia or malignancy (P = 0.11).
Result(s): The average baseline eGFR was 79 mL/min +/- 27 mL/min in the covered group and 86 mL/min +/- 25 mL/min in the uncovered group (P = 0.16). There were no statistically significant differences in changes in eGFR from baseline between the two cohorts following IVC stent placement (Table 1). No patients in either cohort developed renal vein thrombosis following IVC stent placement based on imaging and clinical follow-up. There were no statistically significant differences in primary patency between the two groups with a 2-year primary patency rate of 61% in the covered group and 70% in the uncovered group (P=0.11).
Conclusion(s): In this single-center, retrospective cohort study, renal function, thrombosis, and patency outcomes following IVC stent placement did not differ significantly based on the relation of the IVC stent to the renal veins. This suggests that IVC stent placement across the renal veins is safe and effective for treating symptomatic stenosis in the perirenal IVC. [Formula presented]
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Stem cell - like tumor propagating cells self-renew to drive clonal expansion or differentiate into post-mitotic cells without tumorigenic potential in squamous cell carcinomas. This fate choice is governed by a transcriptional network comprised of SOX2-PITX1-TP63 driven self-renewal and KLF4 dependent differentiation circuits. Yet, how stem cell - like tumor propagating cells switch from self-renewal to differentiation remains elusive. Here, we report that this cell fate choice is governed by a bi-stable Klf4 enhancer that is occupied by the transcription factor SOX2 in self-renewing or KLF4 in differentiating squamous cell carcinoma cells, dependent on whether SOX2 is phosphorylated. We will present proteomic, transcriptomic, chromatin immunoprecipitation sequencing, chromatin conformation capture sequencing, and conditional gene targeting data leading to the discovery of a molecular mechanism that governs self-renewal, differentiation, squamous cell carcinoma promotion and growth. The identified mechanism provides a novel path towards the future development of differentiation therapies that could inhibit squamous carcinogenesis in patients.
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Genetic evidence has increasingly linked lysosome dysfunction to an impaired autophagy-lysosomal pathway (ALP) flux in Alzheimer disease (AD) although the relationship of these abnormalities to other pathologies is unclear. In our recent investigation on the origin of impaired autophagic flux in AD, we established the critical early role of defective lysosomes in 5 mouse AD models. To assess in vivo alterations of autophagy and ALP vesicle acidification, we expressed eGFP-mRFP-LC3 specifically in neurons. We discovered that autophagy dysfunction in these models arises from exceptionally early failure of autolysosome/lysosome acidification, which then drives downstream AD pathogenesis. Extreme autophagic stress in compromised but still intact neurons causes AVs containing toxic APP metabolites, Aβ/β-CTFs, to pack into huge blebs and protrude from the perikaryon membrane. Most notably, AVs also coalesce with ER tubules and yield fibrillar β-amyloid within these tubules. Collectively, amyloid immunoreactivity within these intact neurons assumes the appearance of amyloid-plaques and, indeed, their eventual death transforms them into extracellular plaque lesions. Quantitative analysis confirms that neurons undergoing this transformation are the principal source of β-amyloid-plaques in APP-AD models. These findings prompt reconsideration of the conventionally accepted sequence of events in plaque formation and may help explain the inefficacy of Aβ/amyloid vaccine therapies.

Objective/UNASSIGNED:To describe a unique case of primary ovarian insufficiency and review the systemic barriers in place that hinder reproductive autonomy for Black women who require third-party reproduction. Design/UNASSIGNED:Case report and review of the literature. Setting/UNASSIGNED:Safety-net hospital in an urban community. Patients/UNASSIGNED:A 36-year-old Black woman, gravida 0, with primary ovarian insufficiency who desires future fertility but is restricted by systemic barriers. Interventions/UNASSIGNED:Chromosome analysis. Main Outcome Measures/UNASSIGNED:Not applicable. Results/UNASSIGNED:Balanced reciprocal translocation between chromosomes 1 and 13: 46,XX,t(1;13)(q25;q14.1). Conclusions/UNASSIGNED:The field of assisted reproductive technology has evolved at an exponential rate, yet it unfortunately benefits some and not all. It is imperative that when we advocate for full spectrum infertility care, that this encompasses everyone. As we continue to further study and develop assisted reproductive technology, we must not forget to consider the factors leading to racial and socioeconomic disparities in reproductive care access, utilization, and outcomes.