The crosstalk between neuropilin-1 and tumor necrosis factor-α in endothelial cells.

Tumor necrosis factor-α (TNFα) is a master cytokine which induces expression of chemokines and adhesion molecules, such as intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), in endothelial cells to initiate the vascular inflammatory response. In this study, we identified neuropilin-1 (NRP1), a co-receptor of several structurally diverse ligands, as a modulator of TNFα-induced inflammatory response of endothelial cells. NRP1 shRNA expression suppressed TNFα-stimulated leukocyte adhesion and expression of ICAM-1 and VCAM-1 in human umbilical vein endothelial cells (HUVECs). Likewise, it reduced TNFα-induced phosphorylation of MAPK p38 but did not significantly affect other TNF-induced signaling pathways, such as the classical NFκB and the AKT pathway. Immunofluorescent staining demonstrated co-localization of NRP1 with the two receptors of TNF, TNFR1 and TNFR2. Co-immunoprecipitation further confirmed that NRP1 was in the same protein complex or membrane compartment as TNFR1 and TNFR2, respectively. Modulation of NRP1 expression, however, neither affected TNFR levels in the cell membrane nor the receptor binding affinities of TNFα. Although a direct interface between NRP1 and TNFα/TNFR1 appeared possible from a protein docking model, a direct interaction was not supported by binding assays in cell-free microplates and cultured cells. Furthermore, TNFα was shown to downregulate NRP1 in a time-dependent manner through TNFR1-NFκB pathway in HUVECs. Taken together, our study reveals a novel reciprocal crosstalk between NRP1 and TNFα in vascular endothelial cells.

Pifithrin-µ Induces Stress Granule Formation, Regulates Cell Survival, and Rewires Cellular Signaling.

(1) Background: Stress granules (SGs) are cytoplasmic protein-RNA condensates that assemble in response to various insults. SG production is driven by signaling pathways that are relevant to human disease. Compounds that modulate SG characteristics are therefore of clinical interest. Pifithrin-µ is a candidate anti-tumor agent that inhibits members of the hsp70 chaperone family. While hsp70s are required for granulostasis, the impact of pifithrin-µ on SG formation is unknown. (2) Methods: Using HeLa cells as model system, cell-based assays evaluated the effects of pifithrin-µ on cell viability. Quantitative Western blotting assessed cell signaling events and SG proteins. Confocal microscopy combined with quantitative image analyses examined multiple SG parameters. (3) Results: Pifithrin-µ induced bona fide SGs in the absence of exogenous stress. These SGs were dynamic; their properties were determined by the duration of pifithrin-µ treatment. The phosphorylation of eIF2α was mandatory to generate SGs upon pifithrin-µ exposure. Moreover, the formation of pifithrin-µ SGs was accompanied by profound changes in cell signaling. Pifithrin-µ reduced the activation of 5'-AMP-activated protein kinase, whereas the pro-survival protein kinase Akt was activated. Long-term pifithrin-µ treatment caused a marked loss of cell viability. (4) Conclusions: Our study identified stress-related changes in cellular homeostasis that are elicited by pifithrin-µ. These insights are important knowledge for the appropriate therapeutic use of pifithrin-µ and related compounds.

SC912 inhibits AR-V7 activity in castration-resistant prostate cancer by targeting the androgen receptor N-terminal domain.

Androgen deprivation therapies (ADT) are the mainstay treatments for castration-resistant prostate cancer (CRPC). ADT suppresses the androgen receptor (AR) signaling by blocking androgen biosynthesis or inhibiting AR with antiandrogens that target AR's ligand-binding domain (LBD). However, the ADT's effect is short-lived, as the AR signaling inevitably arises again, which is frequently coupled with AR-V7 overexpression. AR-V7 is a truncated form of AR that lacks the LBD, thus being constitutively active in the absence of androgens and irresponsive to AR-LBD-targeting inhibitors. Though compelling evidence has tied AR-V7 to drug resistance in CRPC, pharmacological inhibition of AR-V7 is still an unmet need. Here, we discovered a small molecule, SC912, which binds to full-length AR as well as AR-V7 through AR N-terminal domain (AR-NTD). This pan-AR targeting relies on the amino acids 507-531 in the AR-NTD. SC912 also disrupted AR-V7 transcriptional activity, impaired AR-V7 nuclear localization and DNA binding. In the AR-V7 positive CRPC cells, SC912 suppressed proliferation, induced cell-cycle arrest, and apoptosis. In the AR-V7 expressing CRPC xenografts, SC912 attenuated tumor growth and antagonized intratumoral AR signaling. Together, these results suggested the therapeutic potential of SC912 for CRPC.

Design and performance of an ultrahigh vacuum spectroscopic-imaging scanning tunneling microscope with a hybrid vibration isolation system.

A spectroscopic imaging-scanning tunneling microscope (SI-STM) allows for the atomic scale visualization of the surface electronic and magnetic structure of novel quantum materials with a high energy resolution. To achieve the optimal performance, a low vibration facility is required. Here, we describe the design and performance of an ultrahigh vacuum STM system supported by a hybrid vibration isolation system that consists of a pneumatic passive and a piezoelectric active vibration isolation stage. We present the detailed vibrational noise analysis of the hybrid vibration isolation system, which shows that the vibration level can be suppressed below 10-8 m/sec/√Hz for most frequencies up to 100 Hz. Combined with a rigid STM design, vibrational noise can be successfully removed from the tunneling current. We demonstrate the performance of our STM system by taking high resolution spectroscopic maps and topographic images on several quantum materials. Our results establish a new strategy to achieve an effective vibration isolation system for high-resolution STM and other scanning probe microscopies to investigate the nanoscale quantum phenomena.

Theoretical Investigation of the Adsorbate and Potential-Induced Stability of Cu Facets During Electrochemical CO2 and CO Reduction.

The activity and product selectivity of electrocatalysts for reactions like the carbon dioxide reduction reaction (CO2RR) are intimately dependent on the catalyst's structure and composition. While engineering catalytic surfaces can improve performance, discovering the key sets of rational design principles remains challenging due to limitations in modeling catalyst stability under operating conditions. Herein, we perform first-principles density functional calculations adopting implicit solvation methods with potential control to study the influence of adsorbates and applied potential on the stability of different facets of model Cu electrocatalysts. Using coverage dependencies extracted from microkinetic models, we describe an approach for calculating potential and adsorbate-dependent contributions to surface energies under reaction conditions, where Wulff constructions are used to understand the morphological evolution of Cu electrocatalysts under CO2RR conditions. We identify that CO*, a key reaction intermediate, exhibits higher kinetically and thermodynamically accessible coverages on (100) relative to (111) facets, which can translate into an increased relative stabilization of the (100) facet during CO2RR. Our results support the known tendency for increased (111) faceting of Cu nanoparticles under more reducing conditions and that the relative increase in (100) faceting observed under CO2RR conditions is likely attributed to differences in CO* coverage between these facets.

The influence of posterior acromial morphology on outcomes and return to pushups in young patients undergoing arthroscopic posterior capsulolabral repair.

Background: Prior evidence has identified specific posterior acromial morphology as significantly associated with unidirectional posterior shoulder instability. The purpose of this study is to determine the influence of posterior acromial morphology on the outcomes of arthroscopic posterior capsulolabral repair (APCLR) for unidirectional posterior shoulder instability. Additionally, we sought to determine the influence of posterior acromial morphology on the rate and time to return to pushups following APCLR. Methods: We performed a retrospective review of prospectively collected data. The study included consecutive patients undergoing APCLR. Data collected included demographics, radiographic measurements including posterior acromial height (PAH) and posterior acromial tilt on preoperative scapular-Y radiographs, and patient-reported outcome measures at the preoperative and postoperative visits. In addition, starting at 6 months postoperative, patients were asked if they could perform pushups defined as at least 10 repetitions. At the final follow-up, we collected the number of pushups patients were able to perform. Results: Thirty-two consecutive patients underwent APCLR with a mean follow-up of 26 months (range, 12-41). Significant improvement from preoperative to 2 years postoperative was demonstrated in Subjective Shoulder Value (50-85), VAS (6-2.5), American Shoulder and Elbow Surgeons (48 to 83), and Western Ontario Shoulder Instability (WOSI) (1437-777), P = .001. The recurrent instability rate was 3/32 (9%). Patients with PAH > 23 (N = 17) had a recurrent instability rate of 18% (3/17) versus PAH ≤ 23 (N = 15) 0% (0/15), worse WOSI scores (P = .41), and a lower number of pushups (P = .48). The percentage of patients reporting the ability to perform pushups was (6 months/1 year/2 years) (50%/78%/95%). The mean number of pushups reported at the final follow-up was 33 (range, 1-60). Discussion: Following APCLR, approximately 50% of patients resume pushups at 6 months postoperatively, and 80% return at 1 year. Patients reported performing a mean of 33 pushups following APCLR at the final follow-up. Patients with a PAH greater than 23 on preoperative scapular-Y radiographs had a higher rate of recurrent posterior instability, worse WOSI scores, and lower return to pushups; however, the results did not meet statistical significance. Therefore, future larger studies are needed to determine if posterior acromial morphology is independently associated with worse outcomes and increased recurrent instability rates following APCLR.

A High Rate of Return to Running Is Seen After Both Arthroscopic and Open Shoulder Surgery.

Purpose: To determine the percentage of patients who report the ability to run 1 mile at various time points after arthroscopic and open shoulder surgery. Methods: We performed a retrospective review of prospectively collected data for all active-duty military patients aged 18 to 45 years who underwent shoulder surgery at a single institution over a 2-year period. The rehabilitation protocol discouraged running before 3 months, but all patients were able to return to unrestricted running at 3 months postoperatively. Patients were excluded if they lacked 1-year follow-up data. Parameters collected included demographic information and validated patient-reported outcome measures at the preoperative and short-term postoperative visits, as well as patients' ability to run at least 1 mile postoperatively. Results: A total of 126 patients were identified who underwent shoulder surgery with return-to-running data. Compared with baseline, significant improvements in patient-reported outcomes were shown at 1 and 2 years postoperatively (P = .001). The percentage of patients reporting the ability to run 1 mile postoperatively was 59% at 3 months, 74% at 4.5 months, 79% at 6 months, 83% at 12 months, and 91% at 24 months. There was no significant difference in patients undergoing shoulder surgery for instability versus non-instability diagnoses or in patients undergoing open versus arthroscopic anterior stabilization. All 11 patients unable to return to running at final follow-up had chronic lower-extremity diagnoses limiting their running ability. Conclusions: Young military athletes undergoing arthroscopic and open shoulder surgery have a high rate of early return to running. Approximately 60% of patients report the ability to run 1 mile at 3 months postoperatively, and three-quarters of patients do so at 4.5 months. Age, sex, military occupation, underlying diagnosis or type of surgery did not influence the rate of return to running after shoulder surgery. Level of Evidence: Level IV, therapeutic case series.

Oral follicle-stimulating hormone receptor agonist affects granulosa cells differently than recombinant human FSH.

OBJECTIVE: To determine whether TOP5300, a novel oral follicle-stimulating hormone (FSH) receptor (FSHR) allosteric agonist, elicits a different cellular response than recombinant human FSH (rh-FSH) in human granulosa cells from patients undergoing in vitro fertilization. DESIGN: Basic science research with a preclinical allosteric FSHR agonist. SETTING: University hospital. PATIENT(S): Patients with infertility at a single academic fertility clinic were recruited under an Institutional Review Board-approved protocol. Primary granulosa cell cultures were established for 41 patients, of whom 8 had normal ovarian reserve (NOR), 17 were of advanced reproductive age (ARA), 12 had a diagnosis of polycystic ovary syndrome (PCOS), and 4 had a combination of diagnoses, such as ARA and PCOS. INTERVENTION(S): Primary granulosa-lutein (GL) cell cultures were treated with rh-FSH, TOP5300, or vehicle. MAIN OUTCOME MEASURE(S): Estradiol (E2) production using enzyme-linked immunosorbent assay, steroid pathway gene expression of StAR and aromatase using quantitative polymerase chain reaction, and FSHR membrane localization using immunofluorescence were measured in human GL cells. RESULT(S): TOP5300 consistently stimulated E2 production among patients with NOR, ARA, and PCOS. Recombinant FSH was the more potent ligand in GL cells from patients with NOR but was ineffective in cells from patients with ARA or PCOS. The lowest level of FSHR plasma membrane localization was seen in patients with ARA, although FSHR localization was more abundant in cells from patients with PCOS; the highest levels were present in cells from patients with NOR. The localization of FSHR was not affected by TOP5300 relative to rh-FSH in any patient group. TOP5300 stimulated greater expression of StAR and CYP19A1 across cells from all patients with NOR, ARA, and PCOS combined, although rh-FSH was unable to stimulate StAR and aromatase (CYP19A1) expression in cells from patients with PCOS. TOP5300-induced expression of StAR and CYP19A1 mRNA among patients with ARA and NOR was consistently lower than that observed in cells from patients with PCOS. CONCLUSION(S): TOP5300 appears to stimulate E2 production and steroidogenic gene expression from GL cells more than rh-FSH in PCOS, relative to patients with ARA and NOR. It does not appear that localization of FSHR at cell membranes is a limiting step for TOP5300 or rh-FSH stimulation of steroidogenic gene expression and E2 production.

Systematic Exposure in Revision Total Hip Arthroplasty: The Posterior Approach.

As indications for total hip arthroplasty (THA) continue to expand, and patients continue to live longer with more active lifestyles, the incidence of revision THA is expected to rise. General orthopaedic surgeons are now beginning to consider doing revision THA surgery because of the increased revision burden being experienced nationwide. While classical approaches to the hip can be used for simple revisions, extensile exposure techniques in conjunction with selective soft-tissue releases are often required for adequate visualization for more complex revision cases. This review provides a systematic approach to surgical exposure for revision THA using the posterior approach. The surgeon should follow a stepwise progression to obtain safe, adequate, and reproducible visualization of both the acetabulum and the proximal femur.

The Iatrogenic Injury Potential of Self-adherent Elastic Bandages in Finger Injuries.

BACKGROUND: The use of a self-adherent, elastic bandage is a practical way to dress finger injuries. Multiple reports describe iatrogenic injuries from elastic bandages, ranging from skin necrosis to finger gangrene, necessitating amputations. This study investigated whether elastic bandages can compromise digital perfusion by occluding arterial blood flow in healthy volunteers and evaluated the utility of pulse oximetry as a monitoring tool for digital perfusion. A technique for safe bandage application is proposed. METHODS: A commercially available elastic bandage was wrapped around the index finger of 20 healthy volunteers at varying degrees of stretch. Digital perfusion measurements were carried out using photoelectric pulse transduction, laser Doppler flowmetry, and pulse oximetry. Intracompartmental pressure measurements were recorded using a separate in vitro experimental model. RESULTS: Elastic bandages applied at maximum stretch did not change digital brachial index or pulse oximetry values, suggesting arterial blood flow was preserved distal to the bandage. Intracompartmental pressure measurements at maximum stretch remained below the systolic digital pressure. In contrast, superficial dermal perfusion fell to 32% of normal as measured by laser Doppler flow, at 100% bandage stretch. CONCLUSION: This study suggests a risk for iatrogenic injury when using elastic bandages for finger dressings. While arterial inflow was never compromised, pressures were high enough to occlude superficial venous outflow, which may begin at 20% bandage stretch. Pulse oximetry failed to detect changes distal to applied dressings, and we do not recommend it to detect digital vascular compromise in this setting.

Prosthetic Hip Dislocations in Direct Anterior Versus Posterior Approach in Patients With Instrumented Lumbar Fusion.

BACKGROUND: Instrumented posterior lumbar spinal fusion (IPLSF) has been demonstrated to contribute to instability following total hip arthroplasty (THA). It is unclear whether a supine direct anterior (DA) approach reduces the risk of instability. METHODS: A retrospective review of 1,773 patients who underwent THA through either a DA approach or a posterior approach at our institution over a 7-year period was performed. Radiographic and chart reviews were then used to identify our primary group of interest comprised of 111 patients with previous IPLSF. Radiographic review, chart review, and phone survey was performed. Dislocation rates in each approach group were then compared within this cohort of patients with IPLSF. RESULTS: Within the group of patients with IPLSF, 33.3% (n = 37) received a DA approach while 66.6% (n = 74) received a posterior approach. None of the 9 total dislocations in the DA group had IPLSF, whereas 4 of the 16 total dislocations in the posterior approach group had IPLSF (P = .78). When examining the larger group of patients, including those without IPLSF, patients undergoing a DA approach had a lower BMI and were likely have a smaller head size implanted (P < .001 for both). Using Fischer's exact test, fusion was associated with dislocation in the posterior approach group (P < .01), whereas fusion was not associated with dislocation in the anterior approach group (P = 1.0). CONCLUSIONS: While there was no significant difference in dislocation rates between posterior and anterior approach groups, in patients with IPLSF, the anterior approach had a lower percentage of dislocation events compared to the posterior approach.

Rate and time to return to shooting following arthroscopic and open shoulder surgery.

Background: There is limited information on return to shooting following shoulder surgery. The purpose of this study is to determine the rate and timing for resuming shooting a rifle following shoulder surgery. Methods: We performed a retrospective review of prospectively collected data. The study included patients undergoing arthroscopic and open shoulder stabilization for unidirectional shoulder instability, and arthroscopic surgery for rotator cuff tears, SLAP lesions, biceps tendinopathy, and acromioclavicular pathology. Data collected included the laterality of surgery, shooting dominance, and patient-reported outcome measures at the preoperative and postoperative visits. Starting at the 4.5-month clinic visit, patients were asked if they could shoot a military rifle. Results: One hundred patients were identified with arthroscopic and open shoulder surgery with a mean age of 30 years (range, 18-45) and a mean follow-up of 24 months (range, 12-32). The cohort consisted of patients undergoing arthroscopic Bankart repair (n = 23), arthroscopic posterior labral repair (n = 18), open Latarjet (n = 16), mini-open subpectoral biceps tenodesis (OBT) (n = 25), OBT with open distal clavicle resection (DCR) (n = 10), open DCR (n = 4), and arthroscopic rotator cuff repair with concomitant OBT (n = 4). Significant improvement in SSV, VAS, ASES, and WOSI was shown at 1-year postoperative, SSV 85, VAS 2, ASES 85, WOSI 239, P = .001. The percentage of patients reporting the ability to shoot a military rifle postoperatively were 47%, 63%, 85%, and 94% at 4.5 months, 6 months, 1 year, and 2 years, respectively. At 4.5 months postoperatively, patients who underwent surgery ipsilateral to their shooting dominance (n = 59) had a rate of return to shooting (33%) versus shoulder surgery on the contralateral side of shooting dominance (n = 41) (60%), P = .04. However, there was no significant difference in the groups at 6 months and 1 year. Additionally, there was a significant difference in the rate of return to shooting at 6 months in patients undergoing arthroscopic posterior labral repair versus the remainder of the cohort (posterior instability (33%) vs. (69%), P = .016), and a significant difference between posterior shoulder stabilization and anterior shoulder stabilization (70%), P = .03. Conclusion: Patients undergoing arthroscopic and open shoulder surgery have a high rate of return to shooting. Approximately 60% of patients resume shooting at 6 months postoperatively and 85% return at 1 year. Patients undergoing shoulder surgery on the contralateral side of their shooting dominance return to shooting significantly faster than those with shoulder surgery ipsilateral to their shooting dominance. Additionally, those undergoing arthroscopic posterior shoulder stabilization return to shooting at a slower rate than anterior stabilization surgery.

Designing 1D correlated-electron states by non-Euclidean topography of 2D monolayers.

Two-dimensional (2D) bilayers, twisted to particular angles to display electronic flat bands, are being extensively explored for physics of strongly correlated 2D systems. However, the similar rich physics of one-dimensional (1D) strongly correlated systems remains elusive as it is largely inaccessible by twists. Here, a distinctive way to create 1D flat bands is proposed, by either stamping or growing a 2D monolayer on a non-Euclidean topography-patterned surface. Using boron nitride (hBN) as an example, our analysis employing elastic plate theory, density-functional and coarse-grained tight-binding method reveals that hBN's bi-periodic sinusoidal deformation creates pseudo- electric and magnetic fields with unexpected spatial dependence. A combination of these fields leads to anisotropic confinement and 1D flat bands. Moreover, changing the periodic undulations can tune the bandwidth, to drive the system to different strongly correlated regimes such as density waves, Luttinger liquid, and Mott insulator. The 1D nature of these states differs from those obtained in twisted materials and can be exploited to study the exciting physics of 1D quantum systems.

NEDD9 links anaplastic thyroid cancer stemness to chromosomal instability through integrated centrosome asymmetry and DNA sensing regulation.

Stemness and chromosomal instability (CIN) are two common contributors to intratumor heterogeneity and therapy relapse in advanced cancer, but their interplays are poorly defined. Here, in anaplastic thyroid cancer (ATC), we show that ALDH+ stem-like cancer cells possess increased CIN-tolerance owing to transcriptional upregulation of the scaffolding protein NEDD9. Thyroid patient tissues and transcriptomic data reveals NEDD9/ALDH1A3 to be co-expressed and co-upregulated in ATC. Compared to bulk ALDH- cells, ALDH+ cells were highly efficient at propagating CIN due to their intrinsic tolerance of both centrosome amplification and micronuclei. ALDH+ cells mitigated the fitness-impairing effects of centrosome amplification by partially inactivating supernumerary centrosomes. Meanwhile, ALDH+ cells also mitigated cell death caused by micronuclei-mediated type 1 interferon secretion by suppressing the expression of the DNA-sensor protein STING. Both mechanisms of CIN-tolerance were lost upon RNAi-mediated NEDD9 silencing. Both in vitro and in vivo, NEDD9-depletion attenuated stemness, CIN, cell/tumor growth, while enhancing paclitaxel effectiveness. Collectively, these findings reveal that ATC progression can involve an ALDH1A3/NEDD9-regulated program linking their stemness to CIN-tolerance that could be leveraged for ATC treatment.

Electron Optics and Valley Hall Effect of Undulated Graphene.

Electron optics is the systematic use of electromagnetic (EM) fields to control electron motions. In graphene, strain induces pseudo-electromagnetic fields to guide electron motion. Here we demonstrate the use of substrate topography to impart desirable strain on graphene to induce static pseudo-EM fields. We derive the quasi-classical equation of motion for Dirac Fermions in a pseudo-EM field in graphene and establish the correspondence between the quasi-classical and quantum mechanical snake states. Based on the trajectory analysis, we design sculpted substrates to realize various "optical devices" such as a converging lens or a collimator, and further propose a setup to achieve valley Hall effect solely through substrate patterning, without any external fields, to be used in valleytronics applications. Finally, we discuss how the predicted strain/pseudo-EM field patterns can be experimentally sustained by typical substrates and generalized to other 2D materials.

Formal Orthopaedic Surgery "Boot Camp" Curriculum to Optimize Performance on Acting Internships.

Orthopaedic surgery is one of the most competitive residency specialties in the National Residency Matching Program. To improve the odds of matching, senior medical students applying in the field participate in orthopaedic surgery away rotations with programs across the country. Students who do well on these rotations have a higher likelihood of matching because clinical performance is a principal criterion used by admissions committees to rank applicants. On the other hand, these rotations can be physically and emotionally taxing on medical students because poor performance can negatively affect their application and, thus, chances of matching at that institution. Unfortunately, the resources provided by medical schools to prepare students for these high-stakes rotations are usually sparse and unstructured. To address this gap in training at our institution, we developed a formal "boot camp" offered through the university to prepare interested senior medical students for their orthopaedic surgery acting internships. This course focuses on building a solid foundation of musculoskeletal knowledge and exposing students to surgical and procedural skills that are fundamental to the practice of orthopaedic surgery. Over the 2 years, this course has been offered at our institution, and it has proven successful in outcome measures, such as student satisfaction and preparedness, student orthopaedic knowledge, program director evaluations, and match rate. This article describes the novel 1-month curriculum, which includes lectures, laboratory, and clinical experience.

High Incidence of Anterior Shoulder Pain in Young Athletes Undergoing Arthroscopic Posterior Labral Repair for Posterior Shoulder Instability.

PURPOSE: The purposes of this study were to determine the incidence of anterior shoulder pain in young athletes undergoing arthroscopic posterior labral repair for symptomatic unidirectional posterior shoulder instability and in patients with preoperative anterior shoulder pain treated without biceps tenodesis at the time of arthroscopic posterior labral repair who underwent a revision biceps tenodesis procedure at short-term follow up. METHODS: A retrospective review was performed at a single institution over a 24-month period. The study included young patients who underwent an arthroscopic posterior labral repair for symptomatic unidirectional posterior shoulder instability. The electronic medical record, magnetic resonance arthrograms, and arthroscopic images were reviewed to exclude patients with posterior labral tears with anterior labral tear or SLAP (superior labrum anterior-to-posterior) tear extension on advanced imaging and arthroscopic examination. Data collected included the presence of preoperative tenderness to palpation of the biceps tendon in the groove, the results of a preoperative Speed test, postoperative Subjective Shoulder Value, the presence of postoperative anterior shoulder pain, and the need for a secondary biceps tenodesis. RESULTS: We identified 65 patients who underwent arthroscopic labral repair for posterior shoulder instability. From this cohort, 26 patients with symptomatic unidirectional posterior shoulder instability underwent an arthroscopic posterior labral repair. The incidence of preoperative anterior shoulder pain with Zone 2 biceps groove tenderness and a positive Speed test was identified in 20 of 26 patients (76.9%). Of 26 patients, 5 (19%) had concomitant biceps tenodesis. The median postoperative Subjective Shoulder Value was 80 (interquartile range, 60-90) at median follow-up of 2.1 years. Of the 20 patients with preoperative anterior shoulder pain, 8 of 20 (40%) reported persistent anterior pain. One patient (4.7%) underwent a secondary biceps tenodesis. CONCLUSIONS: There is a high incidence of anterior shoulder pain and Zone 2 biceps groove tenderness in patients undergoing isolated arthroscopic posterior labral repair for unidirectional posterior shoulder instability. At short-term follow-up, few patients required a secondary biceps tenodesis procedure; however, 30% of patients had persistent anterior shoulder pain. LEVEL OF EVIDENCE: Level IV, retrospective diagnostic case series.

Pharmacological Characterization of Low Molecular Weight Biased Agonists at the Follicle Stimulating Hormone Receptor.

Follicle-stimulating hormone receptor (FSHR) plays a key role in reproduction through the activation of multiple signaling pathways. Low molecular weight (LMW) ligands composed of biased agonist properties are highly valuable tools to decipher complex signaling mechanisms as they allow selective activation of discrete signaling cascades. However, available LMW FSHR ligands have not been fully characterized yet. In this context, we explored the pharmacological diversity of three benzamide and two thiazolidinone derivatives compared to FSH. Concentration/activity curves were generated for Gαs, Gαq, Gαi, ß-arrestin 2 recruitment, and cAMP production, using BRET assays in living cells. ERK phosphorylation was analyzed by Western blotting, and CRE-dependent transcription was assessed using a luciferase reporter assay. All assays were done in either wild-type, Gαs or ß-arrestin 1/2 CRISPR knockout HEK293 cells. Bias factors were calculated for each pair of read-outs by using the operational model. Our results show that each ligand presented a discrete pharmacological efficacy compared to FSH, ranging from super-agonist for ß-arrestin 2 recruitment to pure Gαs bias. Interestingly, LMW ligands generated kinetic profiles distinct from FSH (i.e., faster, slower or transient, depending on the ligand) and correlated with CRE-dependent transcription. In addition, clear system biases were observed in cells depleted of either Gαs or ß-arrestin genes. Such LMW properties are useful pharmacological tools to better dissect the multiple signaling pathways activated by FSHR and assess their relative contributions at the cellular and physio-pathological levels.

Rescue of Cell Surface Expression and Signaling of Mutant Follicle-Stimulating Hormone Receptors.

Mutations in G protein-coupled receptors (GPCRs) underlie numerous diseases. Many cause receptor misfolding and failure to reach the cell surface. Pharmacological chaperones are cell-permeant small molecules that engage nascent mutant GPCRs in the endoplasmic reticulum, stabilizing folding and "rescuing" cell surface expression. We previously demonstrated rescue of cell surface expression of luteinizing hormone receptor mutants by an allosteric agonist. Here we demonstrate that a similar approach can be employed to rescue mutant follicle-stimulating hormone receptors (FSHRs) with poor cell surface expression using a small-molecule FSHR agonist, CAN1404. Seventeen FSHR mutations described in patients with reproductive dysfunction were expressed in HEK 293T cells, and cell surface expression was determined by enzyme-linked immunosorbent assay of epitope-tagged FSHRs before/after treatment with CAN1404. Cell surface expression was severely reduced to ≤18% of wild-type (WT) for 11, modestly reduced to 66% to 84% of WT for 4, and not reduced for 2. Of the 11 with severely reduced cell surface expression, restoration to ≥57% of WT levels was achieved for 6 by treatment with 1 µM CAN1404 for 24 h, and a corresponding increase in FSH-induced signaling was observed for 4 of these, indicating restored functionality. Therefore, CAN1404 acts as a pharmacological chaperone and can rescue cell surface expression and function of certain mutant FSHRs with severely reduced cell surface expression. These findings aid in advancing the understanding of the effects of genetic mutations on GPCR function and provide a proof of therapeutic principle for FSHR pharmacological chaperones.