Faculty Bibliography

The human high-affinity sodium-dicarboxylate cotransporter (NaDC3) imports various substrates into the cell as tricarboxylate acid cycle intermediates, lipid biosynthesis precursors and signaling molecules. Understanding the cellular signaling process and developing inhibitors require knowledge of the structural basis of the dicarboxylate specificity and inhibition mechanism of NaDC3. To this end, we determined the cryo-electron microscopy structures of NaDC3 in various dimers, revealing the protomer in three conformations: outward-open C_o, outward-occluded C_oo and inward-open C_i. A dicarboxylate is first bound and recognized in C_o and how the substrate interacts with NaDC3 in C_oo likely helps to further determine the substrate specificity. A phenylalanine from the scaffold domain interacts with the bound dicarboxylate in the C_oo state and modulates the kinetic barrier to the transport domain movement. Structural comparison of an inhibitor-bound structure of NaDC3 to that of the sodium-dependent citrate transporter suggests ways for making an inhibitor that is specific for NaDC3.

PURPOSE/OBJECTIVE:To assess the association between neoadjuvant therapy and overall survival (OS) in patients with left-sided resectable pancreatic cancer (RPC) compared to upfront surgery. BACKGROUND:Left-sided pancreatic cancer is associated with worse OS compared to right-sided pancreatic cancer. Although neoadjuvant therapy is currently seen as not effective in patients with RPC, current randomized trials included mostly patients with right-sided RPC. METHODS:International multicenter retrospective study including consecutive patients after left-sided pancreatic resection for pathology-proven RPC, either after neoadjuvant therapy or upfront surgery in 76 centers from 18 countries on 4 continents (2013-2019). Primary endpoint is OS from diagnosis. Time-dependent Cox regression analysis was performed to investigate the association of neoadjuvant therapy with OS, adjusting for confounders at time of diagnosis. Adjusted OS probabilities were calculated. RESULTS:=0.96) involvement. CONCLUSIONS:Neoadjuvant therapy in patients with left-sided RPC was associated with improved OS compared to upfront surgery. The impact of neoadjuvant therapy increased with larger tumor size and higher serum CA19-9 at diagnosis. Randomized controlled trials on neoadjuvant therapy specifically in patients with left-sided RPC are needed.

OBJECTIVES/OBJECTIVE:To determine the most common reason for 30-day readmission following hospitalization for hip fractures. METHODS:Design: A retrospective review. SETTING/METHODS:Single academic medical center that includes a Level 1 Trauma Center. PATIENT SELECTION CRITERIA/UNASSIGNED:Included were all patients operatively treated for hip fractures (OTA 31) between October 2014 and November 2023. Patients that died during their initial admission were excluded. OUTCOME MEASURES AND COMPARISONS/UNASSIGNED:Patient demographics, hospital quality measures, outcomes and readmission within 30-days following discharge for each patient were reviewed. 30-day readmission reason was recorded and correlation analysis was performed. RESULTS:A total of 3,032 patients were identified with a mean age of 82.1 years and 70.5% of patients being female. The 30-day readmission cohort was 2.6 years older (p<0.001) and 8.8% more male patients (p=0.027), had 0.5 higher CCI (p<0.001), 0.3 higher ASA class (p<0.001) and were 9.2% less independent at the time of admission (p= 0.003). Hemiarthroplasty procedure (32.7% vs. 24.1%) was associated with higher 30-day readmission compared to closed percutaneous screw fixation (4.5% vs. 8.8%) and cephalomedullary nail fixation (52.2% vs. 54.4%, p<0.001). Those readmitted by 30-days developed more major (16.7% vs. 8.0%) (p<0.001) and minor (50.5% vs. 36.4%) (p<0.001) complications during their initial hospitalization and had a 1.5 day longer LOS during their first admission (p<0.001). Those discharged home were less likely to be readmitted within 30-days (20.7% vs. 27.6%, (p=0.008). Multivariate regression revealed increasing ASA class (O.R. 1.47, p=0.002) and pre-injury ambulatory status (O.R. 1.42, p=0.007) were most associated with increased 30-day readmission. The most common reason for readmission was pulmonary complications (17.1% of complications) including acute respiratory failure, COPD exacerbation and pneumonia. CONCLUSION/CONCLUSIONS:Thirty-day readmission following hip fracture was associated with older, sicker patients with decreased pre-injury ambulation status. Hemiarthroplasty for femoral neck fracture was also associated with readmission. The most common reason for 30-day readmission following hip fracture was pulmonary complications. LEVEL OF EVIDENCE/METHODS:Prognostic Level III.

Estrogen deficiency is considered the most important cause of postmenopausal osteoporosis. However, the underlying mechanism is still not completely understood. In this study, progranulin (PGRN) was isolated as a key regulator of bone mineral density in postmenopausal women through high throughput proteomics screening. In addition, PGRN-deficient mice exhibited significantly lower bone mass than their littermates in an ovariectomy-induced osteoporosis model. Furthermore, estrogen-mediated inhibition of osteoclastogenesis and bone resorption as well as its protection against ovariectomy-induced bone loss largely depended on PGRN. Mechanistic studies revealed the existence of a positive feedback regulatory loop between PGRN and estrogen signaling. In addition, loss of PGRN led to the reduction of estrogen receptor α, the important estrogen receptor involved in estrogen regulation of osteoporosis, through enhancing its degradation via K48-linked ubiquitination. These findings not only provide a previously unrecognized interplay between PGRN and estrogen signaling in regulating osteoclastogenesis and osteoporosis but may also present a new therapeutic approach for the prevention and treatment of postmenopausal osteoporosis by targeting PGRN/estrogen receptor α.

OBJECTIVE:Genome-wide association studies implicate metabo-psychiatric origins for anorexia nervosa (AN). There are two case reports totaling six adult females who experienced complete remission of AN following a treatment comprised of ketogenic diet (targeting metabolism) with ketamine infusions (targeting psychiatric origins), but no study has determined the efficacy of ketogenic diet, alone. We addressed this gap in knowledge, with exploration of potential molecular mechanisms, using an animal model. METHOD/METHODS:Adult C57BL6 female mice underwent 2 or 3 cycles of activity-based anorexia (ABA1, ABA2, ABA3), an animal model of AN relapse, in which AN-like maladaptive behaviors of hyperactivity and voluntary food restriction are elicited when wheel access is combined with food restriction. ABA was categorized as severe, based on weight loss ≥ 20%, food restriction-evoked increase in wheel counts > 10,000/6 h, and crouching/grimace, and compared across two groups: (1) KG, fed ketogenic food continuously (N = 25); and (2) CON, fed standard diet (N = 28). RESULTS:86% of CON versus none of the KG were crouching with grimace during ABA1. 93% of CON versus 11% of KG lost weight severely during ABA2 (p < 0.001, 8% difference of group mean weights). Severe hyperactivity was prevalent among CON (86%) and rare for KG (4%) during ABA2 (p < 0.001 on all food-restricted days). ABA up-regulated BDNF (brain-derived neurotrophic factor) in the hippocampus of both groups but ketone body, β-hydroxybutyrate, in urine was increased only among KG. DISCUSSION/CONCLUSIONS:Ketogenic diet may reduce severity of AN relapse through reduction of compulsive exercise, via mechanisms that are in addition to BDNF up-regulation and involve β-hydroxybutyrate.

The advent of large-scale sequencing in both development and disease has identified large numbers of candidate genes that may be linked to important phenotypes. Validating the function of these candidates in vivo is challenging, due to low efficiency and low throughput of most model systems. We have developed a rapid, scalable system for assessing the role of candidate genes using zebrafish. We generated transgenic zebrafish in which Cas9 was knocked-in to the endogenous mitfa locus, a master transcription factor of the melanocyte lineage. We used this system to identify both cell-autonomous and non-cell autonomous regulators of normal melanocyte development. We then applied this to the melanoma setting to demonstrate that loss of genes required for melanocyte survival can paradoxically promote more aggressive phenotypes, highlighting that in vitro screens can mask in vivo phenotypes. Our high-efficiency genetic approach offers a versatile tool for exploring developmental processes and disease mechanisms that can readily be applied to other cell lineages.

OBJECTIVES/OBJECTIVE:To determine which in-hospital complications following the operative treatment of hip fractures are associated with increased inpatient, 30-day and 1 year mortality. METHODS:Design: Retrospective study. SETTING/METHODS:A single academic medical center and a Level 1 Trauma Center. PATIENT SELECTION CRITERIA/UNASSIGNED:All patients who were operatively treated for hip fractures (OTA/AO 31A, 31B and Vancouver A,B, and C periprosthetic fractures) at a single center between October, 2014 and June, 2023. OUTCOME MEASURES AND COMPARISONS/UNASSIGNED:Occurrence of an in-hospital complication was recorded. Cohorts were based upon mortality time points (during admission, 30-days and 1-year) and compared to patients who were alive at those time points to determine which in- hospital complications were most associated with mortality. Correlation analysis was performed between patients who died and those who were alive at each time point. RESULTS:A total of 3,134 patients (average age of 79.6 years, range 18-104 years and 66.6% female) met inclusion for this study. The overall mortality rate during admission, 30 days and 1 year were found to be 1.6%, 3.9% and 11.1%, respectively. Sepsis was the complication most associated with increased in-hospital mortality (OR: 7.79, 95% CI 3.22 - 18.82, p<0.001) compared to other in-hospital complications. Compared to other in-hospital complications, stroke was the complication most associated with 30-day mortality (OR: 7.95, 95% CI 1.82 - 34.68, p<0.001). Myocardial infarction was the complication most associated with 1-year mortality (OR: 2.86, 95% CI 1.21 - 6.77, p=0.017) compared to other in-hospital complications. CONCLUSIONS:Post-operative sepsis, stroke and myocardial infraction were the three complications most associated with mortality during admission, 30-day mortality and 1-year mortality, respectively, during the operative treatment of hip fractures. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

As efforts to study the mechanisms of melanoma metastasis and novel therapeutic approaches multiply, researchers need accurate, high-throughput methods to evaluate the effects on tumor burden resulting from specific interventions. We show that automated quantification of tumor content from whole slide images is a compelling solution to assess in vivo experiments. In order to increase the outflow of data collection from preclinical studies, we assembled a large dataset with annotations and trained a deep neural network for the quantitative analysis of melanoma tumor content on histopathological sections of murine models. After assessing its performance in segmenting these images, the tool obtained consistent results with an orthogonal method (bioluminescence) of measuring metastasis in an experimental setting. This AI-based algorithm, made freely available to academic laboratories through a web-interface called MetFinder, promises to become an asset for melanoma researchers and pathologists interested in accurate, quantitative assessment of metastasis burden.

Hair follicle neogenesis (HFN) occurs following large skin excisions in mice, serving as a rare regenerative model in mammalian wound healing. Wound healing typically results in fibrosis in mice and humans. We previously showed small skin excisions in mice result in scarring devoid of HFN, displaying features of non-regenerative healing, and Hedgehog (Hh) activation in the dermis of such wounds can induce HFN. In this study, we sought to verify the role of dermal Wnt/β-catenin signaling in HFN, as this pathway is essential for HF development, but is also paradoxically well-characterized in fibrosis of adult wounds. By deletion of β-catenin in large wound myofibroblasts, we show Wnt/β-catenin signaling is required for endogenous mechanisms of HFN. Through utilizing a combined mouse model that simultaneously induces deletion of β-catenin and constitutive activation of Smoothened (Smo) in myofibroblasts, we also found β-catenin is required for Hh-driven DP formation. Transcriptome analysis confirms Wnt/β-catenin and Hh pathways are activated in dermal papilla (DP) cells. Our results indicate that Wnt-active fibrotic status may also create a permissive state for the regenerative function of Hh, suggesting that activation of both Wnt and Hh pathways in skin wound fibroblasts must be ensured in future strategies to promote HFN.