Guanine-containing ssDNA and RNA induce dimeric and tetrameric structural forms of SAMHD1.

The dNTPase activity of tetrameric SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) plays a critical role in cellular dNTP regulation. SAMHD1 also associates with stalled DNA replication forks, DNA repair foci, ssRNA and telomeres. The above functions require nucleic acid binding by SAMHD1, which may be modulated by its oligomeric state. Here we establish in cryo-EM and biochemical studies that the guanine-specific A1 activator site of each SAMHD1 monomer is used to target the enzyme to guanine nucleotides within single-stranded (ss) DNA and RNA. Remarkably, nucleic acid strands containing a single guanine base induce dimeric SAMHD1, while two or more guanines with ∼20 nucleotide spacing induce a tetrameric form. A cryo-EM structure of ssRNA-bound tetrameric SAMHD1 shows how ssRNA strands bridge two SAMHD1 dimers and stabilize the structure. This ssRNA-bound tetramer is inactive with respect to dNTPase and RNase activity.

Phosphorylation of SAMHD1 Thr592 increases C-terminal domain dynamics, tetramer dissociation and ssDNA binding kinetics.

SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) is driven into its activated tetramer form by binding of GTP activator and dNTP activators/substrates. In addition, the inactive monomeric and dimeric forms of the enzyme bind to single-stranded (ss) nucleic acids. During DNA replication SAMHD1 can be phosphorylated by CDK1 and CDK2 at its C-terminal threonine 592 (pSAMHD1), localizing the enzyme to stalled replication forks (RFs) to promote their restart. Although phosphorylation has only a small effect on the dNTPase activity and ssDNA binding affinity of SAMHD1, perturbation of the native T592 by phosphorylation decreased the thermal stability of tetrameric SAMHD1 and accelerated tetramer dissociation in the absence and presence of ssDNA (∼15-fold). In addition, we found that ssDNA binds competitively with GTP to the A1 site. A full-length SAMHD1 cryo-EM structure revealed substantial dynamics in the C-terminal domain (which contains T592), which could be modulated by phosphorylation. We propose that T592 phosphorylation increases tetramer dynamics and allows invasion of ssDNA into the A1 site and the previously characterized DNA binding surface at the dimer-dimer interface. These features are consistent with rapid and regiospecific inactivation of pSAMHD1 dNTPase at RFs or other sites of free ssDNA in cells.

Proceedings of the United Kingdom Periprosthetic Joint Infection Meeting 2022: Combined and Arthroplasty Sessions.

Considerable variation in practice exists in the prevention, diagnosis, and treatment of periprosthetic joint infection (PJI), which is a devastating complication for patients and surgeons. The consensus principle has been increasingly embraced by the orthopaedic community to help guide practice, especially where high-level evidence remains unavailable. The third United Kingdom Periprosthetic Joint Infection (UK PJI) Meeting was held in Glasgow on April 1, 2022, with more than 180 delegates in attendance, representing orthopaedics, microbiology, infectious diseases, plastic surgery, anesthetics, and allied health professions, including pharmacy and arthroplasty nurses. The meeting comprised a combined session for all delegates, and separate breakout sessions for arthroplasty and fracture-related infection. Consensus questions for each session were prepared in advance by the UK PJI working group, based upon topics that were proposed at previous UK PJI Meetings, and delegates participated in an anonymized electronic voting process. We present the findings of the combined and arthroplasty sessions of the meeting in this article, and each consensus topic is discussed in relation to the contemporary literature.

Clinical and radiologic outcomes of Lima ProMade custom 3D-printed glenoid components in primary and revision reverse total shoulder arthroplasty with severe glenoid bone loss: a minimum 2-year follow-up.

BACKGROUND: The purpose of this study is to report the clinical and radiologic outcomes of patients undergoing primary or revision reverse total shoulder arthroplasty using custom 3D-printed components to manage severe glenoid bone loss with a minimum of 2-year follow-up. METHODS: Following ethical approval, patients were identified and invited to participate. Inclusion criteria were (1) severe glenoid bone loss necessitating the need for custom implants and (2) patients with definitive glenoid and humeral components implanted more than 2 years prior. Included patients underwent clinical assessment using the Oxford Shoulder Score (OSS), Constant-Murley score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and the quick Disabilities of the Arm, Shoulder, and Hand questionnaire (QuickDASH). Radiographic assessment included anteroposterior and axial projections. Patients were invited to attend a computed tomography (CT) scan to confirm osseointegration. Statistical analysis used descriptive statistics (mean and standard deviation [SD]) and paired t test for parametric data. RESULTS: Eleven patients declined to participate. Five patients were deceased prior to study commencement, leaving 42 remaining patients in this analysis. Three patients had revision surgery before the 2-year follow-up; of these, 2 retained their custom glenoid components. Mean follow-up was 31.6 months from surgery (range 24-52 months). All 4 scores improved: OSS from a mean 15 (SD 8.4) to 36 (SD 12) (P < .001), Constant-Murley score from a mean 15 (SD 11.2) to 52 (SD 20.1) (P < .001), QuickDASH from a mean 70 (SD 21) to 31 (SD 24.8) (P = .004), and the ASES score from a mean 22 (SD 17.8) to 71 (SD 23.3) (P = .007). Radiologic evaluation demonstrated good osseointegration in all but 1 included patient. CONCLUSION: The utility of custom 3D-printed components for managing severe glenoid bone loss in primary and revision reverse total shoulder arthroplasty yields significant clinical improvements in this complex cohort. Large complex glenoid bone defects can be managed successfully with custom 3D-printed glenoid components.

Cooperation Between Distinct Cancer Driver Genes Underlies Intertumor Heterogeneity in Hepatocellular Carcinoma.

BACKGROUND AND AIMS: The pattern of genetic alterations in cancer driver genes in patients with hepatocellular carcinoma (HCC) is highly diverse, which partially explains the low efficacy of available therapies. In spite of this, the existing mouse models only recapitulate a small portion of HCC inter-tumor heterogeneity, limiting the understanding of the disease and the nomination of personalized therapies. Here, we aimed at establishing a novel collection of HCC mouse models that captured human HCC diversity. METHODS: By performing hydrodynamic tail-vein injections, we tested the impact of altering a well-established HCC oncogene (either MYC or ß-catenin) in combination with an additional alteration in one of eleven other genes frequently mutated in HCC. Of the 23 unique pairs of genetic alterations that we interrogated, 9 were able to induce HCC. The established HCC mouse models were characterized at histopathological, immune, and transcriptomic level to identify the unique features of each model. Murine HCC cell lines were generated from each tumor model, characterized transcriptionally, and used to identify specific therapies that were validated in vivo. RESULTS: Cooperation between pairs of driver genes produced HCCs with diverse histopathology, immune microenvironments, transcriptomes, and drug responses. Interestingly, MYC expression levels strongly influenced ß-catenin activity, indicating that inter-tumor heterogeneity emerges not only from specific combinations of genetic alterations but also from the acquisition of expression-dependent phenotypes. CONCLUSIONS: This novel collection of murine HCC models and corresponding cell lines establishes the role of driver genes in diverse contexts and enables mechanistic and translational studies.

Radiofrequency ablation for osteoid osteoma - Recurrence rates and predictive factors.

BACKGROUND AND PURPOSE: Osteoid osteoma is an infrequent but debilitating benign bone lesion which can be successfully managed by percutaneous radiofrequency ablation (RFA). There are few studies investigating the efficacy and follow-up of this treatment. An arbitrary upper limit of 15 mm has been used to differentiate between osteoid osteoma and osteoblastoma with surgery used for lesions above this limit. We aimed to analyse the cases identified from our prospectively maintained database over a ten year period since adoption of this technique in our unit. The primary objectives were to investigate factors which influenced recurrence and the time period at which patients are at risk of this. BASIC PROCEDURES: Consecutive patients with confirmed osteoid osteoma were included. Patient demographics, complications, and recurrence were recorded and multiple regression analysis was performed to investigate causation. MAIN FINDINGS: Within a minimum follow up of 21 months (mean 72), a recurrence rate of 16.3% was noted, higher than the published literature. Cox regression analysis to predict chance of recurrence revealed a relationship between larger lucent diameter and recurrence (p = 0.049, CI 95%, hazard ratio 1.33). CONCLUSIONS: The traditional cut off between osteoid osteoma and osteoblastoma appears less rigidly defined than previously thought and probably represents a progressive scale with larger lesions responding less well to RFA. This study indicates that each millimetre increase represents a ×1.33 chance of recurrence. Clinicians should counsel patients accordingly with lesions approaching the larger limits of this diagnosis.

Epidemiology of glenohumeral dislocation and subsequent instability in an urban population.

BACKGROUND: Glenohumeral dislocation is the most commonly encountered adult joint instability. The epidemiology in the United Kingdom and worldwide is unclear and often limited to young, active groups that are not representative of general populations. Information regarding epidemiology and outcome from a first dislocation is useful for trauma service planning and patient counseling. We calculated the incidence of shoulder instability after a first dislocation in our urban population and investigated predictors of recurrent instability. METHODS: A prospectively collected trauma database was retrospectively examined to identify patients with a first-time dislocation. Demographics, subsequent dislocation, and instability details were collected from electronic patient records. RESULTS: In a 38-month study period, 329 first dislocations occurred in a population of 475,147 with mean follow-up 28.5 months (range, 10-50 months). The overall incidence for first-time dislocations in this population was 21.9 per 100,000 population, of which 7.9% sustained a redislocation and 6.1% had further symptomatic instability. There were 18.8% with associated greater tuberosity fractures, 8.8% sustained a nerve injury, and 2.7% were posterior dislocations. A bimodal distribution was observed for males (peak incidence per 100,000 of 42.1 and 50.9 in 15-24 and ≥85 age groups, respectively), and unimodal for females (peak 45.7 in the 65-74 age group). CONCLUSION: We demonstrate a previously unreported burden of dislocation in older age groups and suggest a rate of recurrence lower than previously reported in the United Kingdom. The group aged 15 to 19 years was at the highest risk of recurrent dislocation and instability. Gender was not a significant predictor of instability.

Single-reviewer electronic phenotyping validation in operational settings: Comparison of strategies and recommendations.

OBJECTIVE: Develop evidence-based recommendations for single-reviewer validation of electronic phenotyping results in operational settings. MATERIAL AND METHODS: We conducted a randomized controlled study to evaluate whether electronic phenotyping results should be used to support manual chart review during single-reviewer electronic phenotyping validation (N=3104). We evaluated the accuracy, duration and cost of manual chart review with and without the availability of electronic phenotyping results, including relevant patient-specific details. The cost of identification of an erroneous electronic phenotyping result was calculated based on the personnel time required for the initial chart review and subsequent adjudication of discrepancies between manual chart review results and electronic phenotype determinations. RESULTS: Providing electronic phenotyping results (vs not providing those results) was associated with improved overall accuracy of manual chart review (98.90% vs 92.46%, p<0.001), decreased review duration per test case (62.43 vs 76.78s, p<0.001), and insignificantly reduced estimated marginal costs of identification of an erroneous electronic phenotyping result ($48.54 vs $63.56, p=0.16). The agreement between chart review and electronic phenotyping results was higher when the phenotyping results were provided (Cohen's kappa 0.98 vs 0.88, p<0.001). As a result, while accuracy improved when initial electronic phenotyping results were correct (99.74% vs 92.67%, N=3049, p<0.001), there was a trend towards decreased accuracy when initial electronic phenotyping results were erroneous (56.67% vs 80.00%, N=55, p=0.07). Electronic phenotyping results provided the greatest benefit for the accurate identification of rare exclusion criteria. DISCUSSION: Single-reviewer chart review of electronic phenotyping can be conducted more accurately, quickly, and at lower cost when supported by electronic phenotyping results. However, human reviewers tend to agree with electronic phenotyping results even when those results are wrong. Thus, the value of providing electronic phenotyping results depends on the accuracy of the underlying electronic phenotyping algorithm. CONCLUSION: We recommend using a mix of phenotyping validation strategies, with the balance of strategies based on the anticipated electronic phenotyping error rate, the tolerance for missed electronic phenotyping errors, as well as the expertise, cost, and availability of personnel involved in chart review and discrepancy adjudication.

The Moral Frameworks and Foundations of Contesting Orientations.

According to contesting theory (Shields & Bredemeier, 2011), people conceptualize competition either through a metaphor of partnership or war. These two alternate metaphors suggest differing sociomoral relationships among the participants. In the current study of intercollegiate athletes (n = 610), we investigated the two approaches to contesting in relation to formalist and consequentialist moral frameworks (Brady & Wheeler, 1996) and individualizing and binding moral foundations (Haidt, 2001). Correlational analysis indicated that the partnership approach correlated significantly with all four moral dimensions, while the war approach correlated with formalist and consequentialist frameworks and binding foundations (i.e., appeals to in-group loyalty, authority, and purity). Multiple regressions demonstrated that the best predictors of a partnership approach were formalist thinking and endorsement of individualizing moral foundations (i.e., appeal to fairness and welfare). Among our primary variables, the best predictors of a war orientation were consequentialist thinking and endorsement of binding foundations.

Predictors of Moral Disengagement in Sport.

Researchers have made productive use of Bandura's (1991) construct of moral disengagement (MD) to help explain why sport participants deviate from ethical ideals. In this study of intercollegiate athletes from diverse sports (N = 713), we examined MD in relation to other character-related variables: empathy, moral identity, moral attentiveness, and contesting orientations. We also examined whether moral attentiveness conforms to the pattern of "bracketed morality" found in moral reasoning (Shields & Bredemeier, 1995) and moral behavior (Kavussanu, Boardley, Sagar, & Ring, 2013). Results indicated that MD correlated positively with perceptual moral attentiveness and war contesting orientation; MD correlated negatively with empathy, moral identity, reflective moral attentiveness, and partnership contesting orientation. Results of hierarchical regression demonstrated that gender, contesting orientations, moral identity, and one form of moral attentiveness were significant predictors of MD. Finally, sport participants were found to be less morally attentive in sport than in everyday life.

Notch promotes vascular maturation by inducing integrin-mediated smooth muscle cell adhesion to the endothelial basement membrane.

Vascular development and angiogenesis initially depend on endothelial tip cell invasion, which is followed by a series of maturation steps, including lumen formation and recruitment of perivascular cells. Notch ligands expressed on the endothelium and their cognate receptors expressed on perivascular cells are involved in blood vessel maturation, though little is known regarding the Notch-dependent effectors that facilitate perivascular coverage of nascent vessels. Here, we report that vascular smooth muscle cell (VSMC) recognition of the Notch ligand Jagged1 on endothelial cells leads to expression of integrin αvß3 on VSMCs. Once expressed, integrin αvß3 facilitates VSMC adhesion to VWF in the endothelial basement membrane of developing retinal arteries, leading to vessel maturation. Genetic or pharmacologic disruption of Jagged1, Notch, αvß3, or VWF suppresses VSMC coverage of nascent vessels and arterial maturation during vascular development. Therefore, we define a Notch-mediated interaction between the developing endothelium and VSMCs leading to adhesion of VSMCs to the endothelial basement membrane and arterial maturation.

A role for VEGF as a negative regulator of pericyte function and vessel maturation.

Angiogenesis does not only depend on endothelial cell invasion and proliferation: it also requires pericyte coverage of vascular sprouts for vessel stabilization. These processes are coordinated by vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) through their cognate receptors on endothelial cells and vascular smooth muscle cells (VSMCs), respectively. PDGF induces neovascularization by priming VSMCs/pericytes to release pro-angiogenic mediators. Although VEGF directly stimulates endothelial cell proliferation and migration, its role in pericyte biology is less clear. Here we define a role for VEGF as an inhibitor of neovascularization on the basis of its capacity to disrupt VSMC function. Specifically, under conditions of PDGF-mediated angiogenesis, VEGF ablates pericyte coverage of nascent vascular sprouts, leading to vessel destabilization. At the molecular level, VEGF-mediated activation of VEGF-R2 suppresses PDGF-Rbeta signalling in VSMCs through the assembly of a previously undescribed receptor complex consisting of PDGF-Rbeta and VEGF-R2. Inhibition of VEGF-R2 not only prevents assembly of this receptor complex but also restores angiogenesis in tissues exposed to both VEGF and PDGF. Finally, genetic deletion of tumour cell VEGF disrupts PDGF-Rbeta/VEGF-R2 complex formation and increases tumour vessel maturation. These findings underscore the importance of VSMCs/pericytes in neovascularization and reveal a dichotomous role for VEGF and VEGF-R2 signalling as both a promoter of endothelial cell function and a negative regulator of VSMCs and vessel maturation.

Clinical outcome of wedged glenoid reconstruction in anatomic total shoulder arthroplasty for osteoarthritic retroverted glenoid: a minimum 2-year follow-up.

Background: Glenoid retroversion and humeral head subluxation is a progressive disorder due to abnormal force coupling and increased contact force. In situ placement of anatomic total shoulder arthroplasty (TSA) components in this scenario results in edge loading, progressive subluxation, and early failure. Wedged glenoid components have been demonstrated to improve glenohumeral alignment, but have not been correlated with mid-term clinical outcomes. Methods: Patients undergoing TSA using a wedged all-polyethylene glenoid component for retroverted glenoid deformity were identified from a prospectively maintained database. Preoperative planning computed tomography was routinely performed and compared to postoperative correction on radiographic evaluation. Evidence of loosening was correlated to prospectively collect clinical outcome using patient-reported outcome measures. A matched group of neutrally aligned glenohumeral joints undergoing anatomic TSA was used to compare improvement in clinical outcomes. Results: Over a 5-year period, 17 patients with mean age 60 (range 43-81, standard deviation 10.5) were identified with a mean preoperative neoglenoid retroversion of 16.7° (standard deviation 4.5). At a mean follow-up of 43.8 months (range 27-60), no revision surgeries were undertaken. Improvement in the Oxford Shoulder Score was 18 points (P < .0001). The mean improvement was compared to a matched control group demonstrating a comparable magnitude of improvement of 20.4 points. Conclusion: Wedged polyethylene components for Walch B2-type glenoids in TSA yield acceptable correction of the joint line, excellent clinical outcomes, and survivorship is maintained in the short term. The clinical and radiological outcome demonstrated similar improvement to that seen in A type deformities.

Mid to Long-Term Outcomes of Grade III-B Open Tibial Fractures Definitively Managed With a Circular Frame: A 13-Year Prospective Database Study at a Major Trauma Center.

OBJECTIVES: The aim of this study was to report experience of a major trauma center utilizing circular frames as definitive fixation in patients sustaining Gustilo-Anderson 3B open tibial fractures. DESIGN: A prospectively maintained database was retrospectively interrogated. SETTING: Single major trauma center in the United Kingdom. PATIENT SELECTION CRITERIA: All patients over the age of 16 sustaining an open tibial fracture with initial debridement performed at the study center. All patients also received orthoplastic care for a soft tissue defect (via skeletal deformation or a soft tissue cover procedure) and subsequent definitive management using an Ilizarov ring fixator. Patients who received primary debridement at another center, had preexisting infection, sustained a periarticular fracture, or those who did not afford a minimum of 12-month follow-up were excluded. Case notes and radiographs were reviewed to collate patient demographics and injury factors. OUTCOME MEASURES AND COMPARISONS: The primary outcome of interest was deep infection rate with secondary outcomes including time to union and secondary interventions. RESULTS: Two hundred twenty-five patients met inclusion criteria. Mean age was 43.2 year old, with 72% males, 34% smokers, and 3% diabetics. Total duration of frame management averaged 6.4 months (SD 7.7). Eight (3.5%) patients developed a deep infection and 41 (20%) exhibited signs of a pin site infection. Seventy-nine (35.1%) patients had a secondary intervention, of which 8 comprised debridement of deep infection, 29 bony procedures, 8 soft tissue operations, 30 frame adjustments, and 4 patients requiring a combination of soft tissue and bony procedures. Bony union was achieved in 221 cases (98.2%), 195 (86.7%) achieved union in a single frame without the need for secondary intervention, 26 required frame adjustments to achieve union. Autologous bone grafts were used in 10 cases. CONCLUSIONS: Orthoplastic care including circular frame fixation for Gustilo-Anderson-3B fractures of the tibia resulted in a low rate of deep infection (3.5%) and achieved excellent union rates (98.2%). LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

RBBP9: a tumor-associated serine hydrolase activity required for pancreatic neoplasia.

Pancreatic cancer is one of the most lethal malignancies. To discover functionally relevant modulators of pancreatic neoplasia, we performed activity-based proteomic profiling on primary human ductal adenocarcinomas. Here, we identify retinoblastoma-binding protein 9 (RBBP9) as a tumor-associated serine hydrolase that displays elevated activity in pancreatic carcinomas. Whereas RBBP9 is expressed in normal and malignant tissues at similar levels, its elevated activity in tumor cells promotes anchorage-independent growth in vitro as well as pancreatic carcinogenesis in vivo. At the molecular level, RBBP9 activity overcomes TGF-beta-mediated antiproliferative signaling by reducing Smad2/3 phosphorylation, a previously unknown role for a serine hydrolase in cancer biology. Conversely, loss of endogenous RBBP9 or expression of mutationally inactive RBBP9 leads to elevated Smad2/3 phosphorylation, implicating this serine hydrolase as an essential suppressor of TGF-beta signaling. Finally, RBBP9-mediated suppression of TGF-beta signaling is required for E-cadherin expression as loss of the serine hydrolase activity leads to a reduction in E-cadherin levels and a concomitant decrease in the integrity of tumor cell-cell junctions. These data not only define a previously uncharacterized serine hydrolase activity associated with epithelial neoplasia, but also demonstrate the potential benefit of functional proteomics in the identification of new therapeutic targets.

Disruption of angiogenesis and tumor growth with an orally active drug that stabilizes the inactive state of PDGFRbeta/B-RAF.

Kinases are known to regulate fundamental processes in cancer including tumor proliferation, metastasis, neovascularization, and chemoresistance. Accordingly, kinase inhibitors have been a major focus of drug development, and several kinase inhibitors are now approved for various cancer indications. Typically, kinase inhibitors are selected via high-throughput screening using catalytic kinase domains at low ATP concentration, and this process often yields ATP mimetics that lack specificity and/or function poorly in cells where ATP levels are high. Molecules targeting the allosteric site in the inactive kinase conformation (type II inhibitors) provide an alternative for developing selective inhibitors that are physiologically active. By applying a rational design approach using a constrained amino-triazole scaffold predicted to stabilize kinases in the inactive state, we generated a series of selective type II inhibitors of PDGFRbeta and B-RAF, important targets for pericyte recruitment and endothelial cell survival, respectively. These molecules were designed in silico and screened for antivascular activity in both cell-based models and a Tg(fli1-EGFP) zebrafish embryogenesis model. Dual inhibition of PDGFRbeta and B-RAF cellular signaling demonstrated synergistic antiangiogenic activity in both zebrafish and murine models of angiogenesis, and a combination of previously characterized PDGFRbeta and RAF inhibitors validated the synergy. Our lead compound was selected as an orally active molecule with favorable pharmacokinetic properties which demonstrated target inhibition in vivo leading to suppression of murine orthotopic tumors in both the kidney and pancreas.

Guanine-containing ssDNA and RNA induce dimeric and tetrameric SAMHD1 in cryo-EM and binding studies.

The dNTPase activity of tetrameric SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) plays a critical role in cellular dNTP regulation. SAMHD1 also associates with stalled DNA replication forks, DNA repair foci, ssRNA, and telomeres. The above functions require nucleic acid binding by SAMHD1, which may be modulated by its oligomeric state. Here we establish that the guanine-specific A1 activator site of each SAMHD1 monomer is used to target the enzyme to guanine nucleotides within single-stranded (ss) DNA and RNA. Remarkably, nucleic acid strands containing a single guanine base induce dimeric SAMHD1, while two or more guanines with ~20 nucleotide spacing induce a tetrameric form. A cryo-EM structure of ssRNA-bound tetrameric SAMHD1 shows how ssRNA strands bridge two SAMHD1 dimers and stabilize the structure. This ssRNA-bound tetramer is inactive with respect to dNTPase and RNase activity.

The RON-receptor regulates pancreatic cancer cell migration through phosphorylation-dependent breakdown of the hemidesmosome.

The recepteur d'origine nantais (RON) receptor tyrosine kinase is overexpressed and stimulates invasive growth in pancreatic cancer cells, yet the mechanisms that underlie RON-mediated phenotypes remain poorly characterized. To better understand RON function in pancreatic cancer cells, we sought to identify novel RON interactants using multidimensional protein identification analysis. These studies revealed plectin, a large protein of the spectrin superfamily, to be a novel RON interactant. Plectin is a multifunctional protein that complexes with integrin-ß4 (ITGB4) to form hemidesmosomes, serves as a scaffolding platform crucial to the function of numerous protein signaling pathways and was recently described as an overexpressed protein in pancreatic cancer (Bausch D et al., Clin Cancer Res 2010; Kelly et al., PLoS Med 2008;5:e85). In this study, we demonstrate that on exposure to its ligand, macrophage-stimulating protein, RON binds to plectin and ITGB4, which results in disruption of the plectin-ITGB4 interaction and enhanced cell migration, a phenotype that can be recapitulated by small hairpin ribosomal nucleic acid (shRNA)-mediated suppression of plectin expression. We demonstrate that disruption of plectin-ITGB4 is dependent on RON and phosphoinositide-3 (PI3) kinase, but not mitogen-activated protein kinase (MEK), activity. Thus, in pancreatic cancer cells, plectin and ITGB4 form hemidesmosomes which serve to anchor cells to the extracellular matrix (ECM) and restrain migration. The current study defines a novel interaction between RON and plectin, provides new insight into RON-mediated migration and further supports efforts to target RON kinase activity in pancreatic cancer.

Comparison of intraocular pressure measurement between rebound, non-contact and Goldmann applanation tonometry in treated glaucoma patients.

BACKGROUND: To compare the intraocular pressure readings obtained with the iCare rebound tonometer and the 7CR non-contact tonometer with those measured by Goldmann applanation tonometry in treated glaucoma patients. DESIGN: A prospective, cross-sectional study was conducted in a private tertiary glaucoma clinic. PARTICIPANTS OR SAMPLES: One hundred nine (54 males : 55 females) patients including only eyes under medical treatment for glaucoma. METHODS: Measurement by Goldmann applanation tonometry, iCare rebound tonometry and 7CR non-contact tonometry. MAIN OUTCOME MEASURES: Intraocular pressure. RESULTS: There were strong correlations between the intraocular pressure measurements obtained with Goldmann and both the rebound and non-contact tonometers (Spearman r-values ≥ 0.79, P < 0.001). However, there were small, statistically significant differences between the average readings for each tonometer. For the rebound tonometer, the mean intraocular pressure was slightly higher compared with the Goldmann applanation tonometer in the right eyes (P = 0.02), and similar in the left eyes (P = 0.93); however, these differences did not reach statistical significance. The Goldmann correlated measurements from the non-contact tonometer were lower than the average Goldmann reading for both right (P < 0.001) and left (P > 0.01) eyes. The corneal compensated measurements from the non-contact tonometer were significantly higher compared with the other tonometers (P ≤ 0.001). CONCLUSIONS: The iCare rebound tonometer and the 7CR non-contact tonometer measure intraocular pressure in fundamentally different ways to the Goldmann applanation tonometer. The resulting intraocular pressure values vary between the instruments and will need to be considered when comparing clinical versus home acquired measurements.

A Systematic Review of the Utility of Intraoperative Navigation During Total Shoulder Arthroplasty.

Total shoulder arthroplasty (TSA) has been demonstrated to successfully recover function to shoulders impaired by arthrosis and rotator cuff insufficiency. Long-term survival depends on the correct positioning of glenoid components and secure bone fixation. Computed tomography (CT)-based intraoperative navigation has proven to be an effective technique for successful TSA procedures. This paper presents a review of CT-based intraoperative navigation considering its advantages and disadvantages. The crucial factors that contribute to the success of this technique are glenoid component positioning, operative duration, and screw selection, which are detailed in this review.