Faculty Bibliography

Small animal models have been a challenge for the study of SARS-CoV-2 transmission, with most investigators using golden hamsters or ferrets ^1,2 . Mice have the advantages of low cost, wide availability, less regulatory and husbandry challenges, and the existence of a versatile reagent and genetic toolbox. However, adult mice do not transmit SARS-CoV-2 ³ . Here we establish a model based on neonatal mice that allows for transmission of clinical SARS-CoV-2 isolates. We characterize tropism, respiratory tract replication and transmission of ancestral WA-1 compared to variants alpha (B.1.1.7), beta (B.1.351), gamma (P.1), delta (B.1.617.2) and omicron (B.1.1.529). We identify inter-variant differences in timing and magnitude of infectious particle shedding from index mice, both of which shape transmission to contact mice. Furthermore, we characterize two recombinant SARS-CoV-2 lacking either the ORF6 or ORF8 host antagonists. The removal of ORF8 shifts viral replication towards the lower respiratory tract, resulting in significantly delayed and reduced transmission. Our results demonstrate the potential of our neonatal mouse model to characterize viral and host determinants of SARS-CoV-2 transmission, while revealing for the first time a role for an accessory protein this context.

PURPOSE/OBJECTIVE:To determine if the DTS decreases radiation exposure (primary outcome measure), fluoroscopy time (secondary outcome measure), and time to distal screw placement (secondary outcome measure) compared to the freehand "perfect circles" method when used for locking of cephalomedullary nails in the treatment of femur fractures METHODS: Fifty-eight patients with hip or femoral shaft fractures that were treated with a long cephalomedullary nail were enrolled in this study. Cohorts were determined based on the method of distal interlocking screw placement into either the "Perfect Circles" or "Distal Targeting" cohort. Time from cephalad screw placement to placement of final distal interlocking screw (seconds), radiation exposure (mGy), and fluoroscopy time (seconds) were compared between groups. Hospital quality measures were compared between cohorts. RESULTS:Use of the DTS resulted in 77% (4.3x) lower radiation exposure (p < 0.001), 64% (2.7x) lower fluoroscopy time (p < 0.001), and 60% (1.7x) lower intraoperative time from end of cephalad screw placement to end of distal interlocking screw placement (p < 0.001) compared to the freehand "perfect circles" method. There was no difference in 30-day or 90-day complication rates between cohorts. CONCLUSION/CONCLUSIONS:The Stryker Gamma3® Distal Targeting System is a safe, effective and efficient alternative to the freehand "perfect circles" method.

INTRODUCTION/BACKGROUND:The inositol polyphosphate-5-phosphatase D (INPP5D) gene encodes a dual-specificity phosphatase that can dephosphorylate both phospholipids and phosphoproteins. Single nucleotide polymorphisms in INPP5D impact risk for developing late onset sporadic Alzheimer's disease (LOAD). METHODS:mice with either tamoxifen (TAM) or corn oil (CO) to induce recombination. RESULTS:deposits and plaque-associated microglia in Inpp5d knockdown mice were increased compared to controls. Spatial transcriptomics identified a plaque-specific expression profile that was extensively altered by Inpp5d knockdown. DISCUSSION/CONCLUSIONS:These results demonstrate that conditional Inpp5d downregulation in the PSAPP mouse increases plaque burden and recruitment of microglia to plaques. Spatial transcriptomics highlighted an extended gene expression signature associated with plaques and identified CST7 (cystatin F) as a novel marker of plaques. HIGHLIGHTS/CONCLUSIONS:Inpp5d knockdown increases plaque burden and plaque-associated microglia number. Spatial transcriptomics identifies an expanded plaque-specific gene expression profile. Plaque-induced gene expression is altered by Inpp5d knockdown in microglia. Our plaque-associated gene signature overlaps with human Alzheimer's disease gene networks.

Neurofilament and tau proteins are neuron-specific cytoskeletal proteins that are enriched in axons, regulated by many of the same protein kinases, interact physically, and are the principal constituents of neurofibrillary lesions in major adult-onset dementias. Both proteins share functions related to the modulation of stability and functions of the microtubule network in axons, axonal transport and scaffolding of organelles, long-term synaptic potentiation, and learning and memory. Expression of these proteins is regulated not only at the transcriptional level but also through posttranscriptional control of pre-mRNA splicing, mRNA stability, transport, localization, local translation and degradation. Current evidence suggests that posttranscriptional determinants of their levels are usually regulated by RNA-binding proteins and microRNAs primarily through 3'-untranslated regions of neurofilament and tau mRNAs. Dysregulations of neurofilament and tau expression caused by mutations or pathologies of RNA-binding proteins such as TDP43, FUS and microRNAs are increasingly recognized in association with varied neurological disorders. In this review, we summarize the current understanding of posttranscriptional control of neurofilament and tau by examining the posttranscriptional regulation of neurofilament and tau by RNA-binding proteins and microRNAs implicated in health and diseases.

OBJECTIVES/OBJECTIVE:To examine the efficacy of regional anesthesia with sedation only for a variety of hip fractures using the newly described lateral femoral cutaneous with over the hip Block (LOH Block). DESIGN/METHODS:Retrospective. SETTING/METHODS:Level-I Trauma CenterPatients/Participants: 40 patients who presented between 11/2021 and 02/2022 for fixation of OTA/AO 31.A1-3 and 31.B1-3 fractures. Matched cohorts of 40 patients who received general anesthesia and 40 patients who received spinal anesthesia for hip fracture fixation were also used. INTERVENTION/METHODS:Operative fixation under LOH block and sedation only. The LOH block is a regional hip analgesic that targets the lateral femoral cutaneous nerve, articular branches of femoral nerve (FN) and accessory obturator nerve (AON). MAIN OUTCOME MEASUREMENTS/METHODS:Demographics, intraoperative characteristics, anesthesia-related complications, hospital quality metrics, and short-term mortality and reoperation rates. RESULTS:A total of 120 patients (40 each: general, spinal, LOH block) were compared. The cohorts were similar in age, race, BMI, gender, CCI, trauma risk score, ambulatory status at baseline, fracture type, and surgical fixation technique performed. Physiologic parameters during surgery were more stable in the LOH block group (p<0.05). Total OR time and anesthesia time were shortest for the LOH block cohort (p<0.05). Patients in the LOH block cohort also had lower post-operative pain scores (p<0.05). Length of hospital stay was shortest for patients in the LOH block cohort (p<0.05), and at time of discharge, patients in the LOH block cohort ambulated the furthest (p<0.05). No differences were found in regards to anesthesia-related complications, palliative care consults, major and minor hospital complications, discharge disposition, reoperation and readmission rates, and mortality rates. CONCLUSIONS:The LOH block is safe and effective anesthesia for the treatment of all types of hip fractures in the elderly requiring surgery. In addition, this block may decrease post-operative pain and length of hospital stay, and also allow for greater ambulation in the early post-operative period for hip fracture patients. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

AIM/OBJECTIVE:The Diabetes risk index (DRI) is a composite of NMR-measured lipoproteins and branched chain amino acids predictive of diabetes mellitus development. Bariatric surgery is indicated in patients with severe obesity, many of whom are at high-risk for developing diabetes. Substantial weight loss occurs following bariatric surgery and sustained weight loss likely contributes to reductions in the development of diabetes and cardiovascular disease. However, some evidence suggests that bariatric surgical procedures themselves may contribute to reducing risk of these conditions independent of weight loss. We aimed to investigate DRI and its association with reductions in body weight and adiposity over one year following bariatric surgery. METHODS:; n = 15). RESULTS:, but DRI decreased so that it no longer differed from that of normal BMI controls (1.9 [1, 17] vs control 12 [1, 20]; p = 0.35). Subjects continued to lose weight, whereas DRI remained similar, throughout follow-up with DRI 1.0 [1, 7] at 12 months. Changes in DRI did not correlate with changes in BMI, body weight or waist circumference at any time during follow-up. There was no difference in change in DRI between surgical procedures or pre-operative metabolic syndrome status. CONCLUSIONS:Our analysis of DRI scores supports the capacity of bariatric surgery to reduce risk of developing diabetes in severely obese individuals. Our findings suggest that bariatric surgical techniques may have inherent effects that improve cardiometabolic risk independent of reductions in body weight or adiposity.

Cultured primary neurons are a well-established model for the study of neuronal function. Conventional stable isotope labeling with amino acids in cell culture (SILAC) requires nearly complete metabolic labeling of proteins and therefore is difficult to apply to cultured primary neurons, which do not divide in culture. In a multiplex SILAC strategy, two different sets of heavy amino acids are used for labeling cells for the different experimental conditions. This allows for straightforward SILAC quantitation using partially labeled cells because the two cell populations are always equally labeled. When combined with bioorthogonal noncanonical amino acid tagging (BONCAT), it allows for comparative proteomic analysis of de novo protein synthesis. Here we describe protocols that utilize the multiplex SILAC labeling strategy for primary cultured neurons to study steady-state and nascent proteomes.

BACKGROUND:The purpose of this study was to compare outcomes following surgical treatment of tibial plateau fractures in an elderly (≥ 65y) and non-elderly (< 65) population. METHODS:Patients with tibial plateau fractures were prospectively followed. Patients were included if they were operatively treated, had an Injury Severity Score of < 16, and had follow-up through 12 months. Clinical, radiographic, and functional outcomes were evaluated at the 3, 6, and 12-month follow-up points. RESULTS:Mean time to radiographic fracture union was by 4.68 and 5.26 months in young and elderly patients, respectively (p = 0.25). There was no difference in self-reported baseline SMFA (p = 0.617). SMFA scores were better in younger patients at 3 months (p = 0.031), however this did not hold when multivariate modeling controlled for other factors. There was no difference at 6 and 12 months (p = 0.475, 0.392). There was no difference in range of knee motion at 3 months. At 6 and 12 months, young patients had statistically but not clinically better range of knee motion (p = 0.045, 0.007). There were no differences in overall reoperation rates, conversion arthroplasty, post-traumatic osteoarthritis or wound complications. CONCLUSIONS:Age greater than 65 does not appear to portend poorer outcomes after surgical repair of a tibial plateau fracture. The complication profiles are similar. Elderly and younger patients had similar function at 12 months compared to their baseline. These data suggest that age should not be a disqualifying factor when considering whether a patient with a tibial plateau fracture should be treated operatively.

PURPOSE/OBJECTIVE:To analyze clinical, radiographic and patient-reported outcomes of distal metaphyseal femoral nonunions treated with fixed-angle plates and screws. METHODS:All patients presenting with a distal metaphyseal femoral fracture nonunion repaired with fixed-angle plating from one urban level 1 trauma center and an orthopedic specialty hospital were identified. Baseline demographic, injury information, and outcomes (healing rates, Short Musculoskeletal Function Assessment, range of motion, and post-operative pain levels) at 12 months following nonunion repair were collected. Outcomes were evaluated between patients fixed with a blade plate and with a locking plate. RESULTS:Of these 31 patients, 27 (87.1%) healed after their index nonunion surgery, 2 (6.5%) healed after one reoperation, 1 (3.2%) healed after 2 reoperations, and 1 (3.2%) had a persistent nonunion but did not want further treatment. At one-year follow-up, the group demonstrated a significant improvement in functional recovery with a mean difference of 14.5 points (p = 0.007) when compared to status before fixed-angle fixation of the nonunion. There was also a significant change in patient-reported pain levels using the VAS scale with a mean difference of 2.0 points (p = 0.009). At one-year follow-up, 11 (39.3%) had full knee range of motion (0-130), 11 (39.3%) had flexion greater than 90 and less than 120°, and 6 (21.4%) had range of motion less than 90°. CONCLUSION/CONCLUSIONS:Patients who undergo fixed angle plating and autogenous bone grafting for distal femoral metapyseal nonunions demonstrate improved functional outcomes and VAS pain score at one year follow up.

PURPOSE/OBJECTIVE:To determine if the type of approach used for treatment of lateral split-depression tibial plateau fractures affects clinical outcome and complications rate. METHODS:This is a retrospective review of 169 patients who presented between 01/2005 and 12/2020 to a Level-I trauma center for operative management of an isolated lateral Schatzker II tibial plateau fractures (AO/OTA Type 41B3.1) treated through a single anterolateral approach: a 90-degree "L" (L), longitudinal vertical (V), or "lazy S" (S). Postoperative radiographic, clinical, and functional outcomes were assessed at 3, 6, 12 months, and beyond. RESULTS:Average time to radiographic healing was longer in the S incision cohort (p < 0.05). Furthermore, patients within the S incision cohort developed more postoperative wound complications at follow-up when compared to those within the L and V incision cohorts (p < 0.05). Additionally, reoperation rates were greater in the S incision cohort (p < 0.05). Lastly, on physical examination of the knee, patients within the S incision cohort had significantly poorer knee range of motion (p < 0.05). CONCLUSIONS:Our study demonstrates that skin incision type in the anterolateral approach to the proximal tibia has an association with outcomes following operative repair of tibial plateau fractures. The information from this study can be used to inform surgeons about the potential complications and long-term outcomes that patients may experience when undergoing operative repair of a tibial plateau fracture through a specific incision type. LEVEL OF EVIDENCE/METHODS:III.