Oral Losartan After Limited Mandibulectomy for Treatment of Desmoid-Type Fibromatosis.

Desmoid-type fibromatosis (DF) is a rare soft tissue lesion with an annual incidence of 2 to 4 per million population and peak incidence occurring at approximately 4.5 years of age. While benign, the tumor has a locally aggressive infiltrative growth pattern and a high rate of recurrence. Given the functional and aesthetic implications of excision and reconstruction in the facial skeleton, novel medical treatment options are highly desirable. We describe the case of a 3-year-old boy who presented with an enlarging, asymptomatic mass involving the left mandible. Biopsy revealed an immunohistochemical profile consistent with DF. Despite the high likelihood of recurrence, conservative, mandible-sparing en bloc resection and limited mandibulectomy were performed. Pathological and immunohistochemical analysis of the resection specimen revealed DF with grossly positive margins and elevated expression of angiotensin II type 1 receptor. Postoperative medical treatment with the angiotensin receptor blocker losartan was initiated. The patient remains medically stable and disease progression-free on repeat imaging at 20 months post-resection. We describe for the first time the successful use of the angiotensin blocker losartan following conservative surgery for management of DF.

Canadian Expert Opinion on Breast Reconstruction Access: Strategies to Optimize Care during COVID-19.

BACKGROUND: Breast reconstructive services are medically necessary, time-sensitive procedures with meaningful health-related quality of life benefits for breast cancer survivors. The COVID-19 global pandemic has resulted in unprecedented restrictions in surgical access, including access to breast reconstructive services. A national approach is needed to guide the strategic use of resources during times of fluctuating restrictions on surgical access due to COVID-19 demands on hospital capacity. METHODS: A national team of experts were convened for critical review of healthcare needs and development of recommendations and strategies for patients seeking breast reconstruction during the pandemic. Following critical review of literature, expert discussion by teleconference meetings, and evidenced-based consensus, best practice recommendations were developed to guide national provision of breast reconstructive services. RESULTS: Recommendations include strategic use of multidisciplinary teams for patient selection and triage with centralized coordinated use of alternate treatment plans during times of resource restrictions. With shared decision-making, patient-centered shifting and consolidation of resources facilitate efficient allocation. Targeted application of perioperative management strategies and surgical treatment plans maximize the provision of breast reconstructive services. CONCLUSIONS: A unified national approach to strategically reorganize healthcare delivery is feasible to uphold standards of patient-centered care for patients interested in breast reconstruction.

Presentation and aetiology of paediatric trigger finger: a systematic review.

Paediatric trigger finger is a rare condition distinct from paediatric trigger thumb and adult trigger digits. We performed a systematic review of paediatric trigger finger presentation and aetiology in order to guide workup and management. Fifty-one studies with 193 patients and 398 trigger fingers were included. Most patients had a single, unilateral trigger finger (54%). Fifty-five patients (29%) had an underlying condition, such as mucopolysaccharidosis; these cases appeared to be associated with multiple or bilateral trigger fingers or with carpal tunnel syndrome. All patients with mucopolysaccharidosis were treated surgically. Conservative management was reported in 33% of all patients, and two-thirds of these did not need further intervention. Patients undergoing surgical release infrequently had recurrence of triggering (6%). We propose an algorithmic approach for patients presenting with paediatric trigger finger. Presence of bilateral or multiple trigger digits or concomitant carpal tunnel syndrome should raise suspicion for an atypical underlying pathology.

Anatomy of the Breast Fascial System: A Systematic Review of the Literature.

BACKGROUND: Understanding the anatomy of the fascial and ligamentous structures of the breast is important in both aesthetic and reconstructive breast surgery. Several structures have been identified that play a significant role in the aesthetic qualities and support of the breast warranting consideration in the context of breast reconstruction. METHODS: The authors performed a systematic review of anatomical, clinical, histologic, and radiologic studies that have described, characterized, and named these structures. The authors have summarized and critically appraised prior research to clarify and define the key fascial structures of the breast, their anatomical function, and their clinical significance in aesthetic and reconstructive breast surgery. RESULTS: Through their review, six distinct breast fascial structures were encountered consistently in the literature. The authors have organized them into intraglandular and extraglandular structures and have reviewed their significance in the context of reconstructive breast surgery. CONCLUSIONS: The primary fascial structures of the breast are important anatomical landmarks with numerous clinical applications. Cooper ligaments divide the breast parenchyma. The superficial and deep layers of the superficial fascia encase the breast in a "pocket," condensing into one thickened layer of fascia along the peripheral breast footprint. The inframammary fold supports and defines the inferior pole. The horizontal septum is a reliable neurovascular landmark. The vertical septum is a newly discovered fascial structure. There are certainly clinical implications that have yet to be described because of the relatively limited and disputed information on the fascia of the female breast and, ultimately, more research is warranted.

The Impact of the COVID-19 Pandemic on Breast Reconstruction: A Canadian Perspective.

BACKGROUND: The COVID-19 pandemic has led to unprecedented challenges and restrictions in surgical access across Canada, including for breast reconstructive services which are an integral component of comprehensive breast cancer care. We sought to determine how breast reconstructive services are being restricted, and what strategies may be employed to optimize the provision of breast reconstruction through a pan-Canadian evaluation from the providers' perspective. METHODS: This was a cross-sectional survey of Canadian plastic and reconstructive surgeons who perform breast reconstruction. The 33-item web-based questionnaire was developed by a pan-Canadian working group of breast reconstruction experts and disseminated via email to members of the Canadian Society of Plastic Surgery. The questionnaire queried respondents on the impact of the COVID-19 pandemic and associated restrictions on surgeons' breast reconstruction practice patterns and opinions on strategies for resource utilization. RESULTS: Responses were received from 49 surgeons, who reported practicing in 8 of 10 Canadian provinces. Restrictions on the provision of breast reconstructive procedures were most limited during the First Wave of the COVID-19 pandemic, where all respondents reported at least some reduction in capacity and more than a quarter reporting complete cessation. Average reported reduction in capacity ranged from 31% to 78% across all 3 waves. Autologous, delayed, and prophylactic reconstructions were most commonly restricted. CONCLUSION: This study provides a pan-Canadian impact assessment on breast reconstructive services during the COVID-19 pandemic from the providers' perspective. To uphold the standards of patient-centred care, a unified approach to strategically reorganize health care delivery now and in the future is needed.

HISTORIQUE: La pandémie de COVID-19 a donné lieu à des défis et des restrictions sans précédent en matière d'accès aux interventions chirurgicales au Canada, y compris les services de reconstruction mammaire qui font partie intégrante des soins complets du cancer du sein. Les chercheurs ont voulu déterminer le mode de restriction des services de reconstruction mammaire et les stratégies possibles pour en optimiser la prestation grâce à une évaluation pancanadienne du point de vue des chirurgiens. MÉTHODOLOGIE: La présente étude transversale a été effectuée auprès de chirurgiens plasticiens et reconstructeurs canadiens qui font de la reconstruction mammaire. Un groupe de travail pancanadien d'experts de la reconstruction mammaire a préparé le questionnaire en ligne en 33 points, lequel a été transmis par courriel aux membres de la Société canadienne de chirurgiens-plasticiens. Le questionnaire portait sur les répercussions de la pandémie de COVID-19 et les restrictions connexes sur les modes de pratique de reconstruction mammaire des chirurgiens, de même que sur leurs avis et stratégies à l'égard de l'utilisation des ressources. RÉSULTATS: Un total de 49 chirurgiens, qui ont déclaré exercer dans huit des dix provinces canadiennes, ont répondu au sondage. Les restrictions imposées aux interventions de reconstruction mammaire ont été plus limitées pendant la première vague de la pandémie COVID-19, puisque tous les répondants ont rendu compte d'au moins une certaine restriction de la capacité et que plus du quart ont fait état de leur arrêt complet. La diminution moyenne de la capacité a varié de 31 % à 78 % dans l'ensemble des trois vagues. Ce sont les reconstructions autologues, tardives et prophylactiques qui ont surtout été touchées. CONCLUSION: La présente étude fournit une évaluation pancanadienne des incidences de la pandémie de COVID-19 sur les services de reconstruction mammaire du point de vue des chirurgiens. Pour maintenir les normes des soins axés sur les patients, il faudra procéder à une réorganisation stratégique unifiée de la prestation des soins, tant maintenant qu'à l'avenir.

Understanding child anxiety before otoplasty: A qualitative study.

BACKGROUND: Pre-operative anxiety in pediatric patients is a major concern in surgical care due to the future medical and behavioral consequences that can occur. The objective of this study was to understand the factors that lead to pre-operative anxiety before otoplasty. METHODS: Participants at a Canadian pediatric hospital were identified to discuss their experience with otoplasty and any anxiety they experienced using a semi-structured interview. Interviews were transcribed and analyzed using a qualitative semantic thematic approach. Major themes were identified and supporting quotes were extracted from the interviews. RESULTS: Ten participants were enrolled in the study. Three main themes (and seven subthemes) were identified: concern for post-operative well-being (perception by others, physical well-being, and negative experiences), fear of the unknown (surgical uncertainty, vulnerability), and support (family and friends, surgeon). CONCLUSIONS: Otoplasty was shown to be an emotional experience for participants with multiple sources of anxiety being identified. While most anxiety sources were similar to those for other pediatric surgeries, a number were specific to otoplasty and its post-operative care plan. This understanding of anxiety will allow physicians and care teams to better prepare patients and their families for otoplasty and enhance the patient's overall experience.

Up-regulation of N-cadherin by Collagen I-activated Discoidin Domain Receptor 1 in Pancreatic Cancer Requires the Adaptor Molecule Shc1.

Pancreatic ductal adenocarcinomas are highly malignant cancers characterized by extensive invasion into surrounding tissues, metastasis to distant organs, and a limited response to therapy. A main feature of pancreatic ductal adenocarcinomas is desmoplasia, which leads to extensive deposition of collagen I. We have demonstrated that collagen I can induce epithelial-mesenchymal transition (EMT) in pancreatic cancer cells. A hallmark of EMT is an increase in the expression of the mesenchymal cadherin N-cadherin. Previously we showed up-regulation of N-cadherin promotes tumor cell invasion and that collagen I-induced EMT is mediated by two collagen receptors, α2ß1-integrin and discoidin domain receptor 1 (DDR1). DDR1 is a receptor-tyrosine kinase widely expressed during embryonic development and in many adult tissues and is also highly expressed in many different cancers. In the signaling pathway initiated by collagen, we have shown proline-rich tyrosine kinase 2 (Pyk2) is downstream of DDR1. In this study we found isoform b of DDR1 is responsible for collagen I-induced up-regulation of N-cadherin and tyrosine 513 of DDR1b is necessary. Knocking down Shc1, which binds to tyrosine 513 of DDR1b via its PTB (phosphotyrosine binding) domain, eliminates the up-regulation of N-cadherin. The signaling does not require a functional SH2 domain or the tyrosine residues commonly phosphorylated in Shc1 but is mediated by the interaction between a short segment of the central domain of Shc1 and the proline-rich region of Pyk2. Taken together, these data illustrate DDR1b, but not DDR1a, mediates collagen I-induced N-cadherin up-regulation, and Shc1 is involved in this process by coupling to both DDR1 and Pyk2.

Is it true that injecting palmar finger skin hurts more than dorsal skin? New level 1 evidence.

BACKGROUND: Since the first texts on local anesthesia were written in the early 1900s, it has been widely quoted and believed that dorsal finger skin is less sensitive to needlestick pain than volar finger skin. The result is that the most commonly used finger block for local anesthesia is the dorsal two injection technique. METHODS: In this study, the needlestick discomfort associated with dorsal and volar finger skin was compared in a group of 78 volunteers who had the long finger of both hands poked with a 25 G needle; one in the midline of the volar side and the other in the lateral web space of the dorsal side. Volunteers then completed a pain scale for each needlestick and ranked which technique they would prefer for future injections. RESULTS: We found that there was no significant difference in needlestick pain or preference of future needle location between the dorsal and volar aspects of the finger. CONCLUSIONS: We provide level 1 evidence that the needlestick of the SIMPLE block which has one needlestick on the volar side of the finger is not more painful than the needlestick of the dorsal finger block.

Assembly of connexin43 into gap junctions is regulated differentially by E-cadherin and N-cadherin in rat liver epithelial cells.

Cadherins have been thought to facilitate the assembly of connexins (Cxs) into gap junctions (GJs) by enhancing cell-cell contact, however the molecular mechanisms involved in this process have remained unexplored. We examined the assembly of GJs composed of Cx43 in isogenic clones derived from immortalized and nontransformed rat liver epithelial cells that expressed either epithelial cadherin (E-Cad), which curbs the malignant behavior of tumor cells, or neuronal cadherin (N-Cad), which augments the invasive and motile behavior of tumor cells. We found that N-cad expression attenuated the assembly of Cx43 into GJs, whereas E-Cad expression facilitated the assembly. The expression of N-Cad inhibited GJ assembly by causing endocytosis of Cx43 via a nonclathrin-dependent pathway. Knock down of N-Cad by ShRNA restored GJ assembly. When both cadherins were simultaneously expressed in the same cell type, GJ assembly and disassembly occurred concurrently. Our findings demonstrate that E-Cad and N-Cad have opposite effects on the assembly of Cx43 into GJs in rat liver epithelial cells. These findings imply that GJ assembly and disassembly are the down-stream targets of the signaling initiated by E-Cad and N-Cad, respectively, and may provide one possible explanation for the disparate role played by these cadherins in regulating cell motility and invasion during tumor progression and invasion.

E-cadherin differentially regulates the assembly of Connexin43 and Connexin32 into gap junctions in human squamous carcinoma cells.

It is as yet unknown how the assembly of connexins (Cx) into gap junctions (GJ) is initiated upon cell-cell contact. We investigated whether the trafficking and assembly of Cx43 and Cx32 into GJs were contingent upon cell-cell adhesion mediated by E-cadherin. We also examined the role of the carboxyl termini of these Cxs in initiating the formation of GJs. Using cadherin and Cx-null cells, and by introducing Cx43 and Cx32, either alone or in combination with E-cadherin, our studies demonstrated that E-cadherin-mediated cell-cell adhesion was neither essential nor sufficient to initiate GJ assembly de novo in A431D human squamous carcinoma cells. However, E-cadherin facilitated the growth and assembly of preformed GJs composed of Cx43, although the growth of cells on Transwell filters was required to initiate the assembly of Cx32. Our results also documented that the carboxyl termini of both Cxs were required in this cell type to initiate the formation of GJs de novo. Our findings also showed that GJ puncta composed of Cx43 co-localized extensively with ZO-1 and actin fibers at cell peripheries and that ZO-1 knockdown attenuated Cx43 assembly. These findings suggest that the assembly of Cx43 and Cx32 into GJs is differentially modulated by E-cadherin-mediated cell-cell adhesion and that direct or indirect cross-talk between carboxyl tails of Cxs and actin cytoskeleton via ZO-1 may regulate GJ assembly and growth.

Expression artifact with retroviral vectors based on pBMN.

While characterizing various splice forms of p120 catenin, we observed what appeared to be a novel posttranslational modification of p120, resulting in a higher molecular weight form that was dependent on the splicing pattern. Further investigation revealed the higher molecular weight form to be a fusion protein between sequences encoded by the retroviral vector and p120. We found that the publicly available sequence of the vector we used does not agree with the experimental sequence. We caution other investigators to be aware of this potential artifact.

E-cadherin/catenin complexes are formed cotranslationally in the endoplasmic reticulum/Golgi compartments.

Cadherins are synthesized with a proregion that lies between a short amino-terminal signal sequence and the first extracellular domain. Following synthesis, the proregion is cleaved, an event that is mandatory for the mature cadherin to function in adhesion. The authors have previously reported that catenins coimmunoprecipate with pro-N-cadherin, and that the N-cadherin/catenin complex forms in the Golgi/endoplasmic reticulum. It is clear that N- and E-cadherin confer significantly different characteristics on cells, and it is possible that N- and E-cadherin/catenin complex formation is equally different. To investigate this, the authors generated an antibody against the proregion of E-cadherin and have used it to examine the assembly of the E-cadherin/catenin complex.

TGF-beta induces formation of F-actin cores and matrix degradation in human breast cancer cells via distinct signaling pathways.

Transforming growth factor beta regulates many biological processes including cell motility and invasion. Podosomes are specialized F-actin rich structures found in normal cells, such as osteoclasts and macrophages. Tumor cells often form related structures called invadopodia that are thought to promote invasion and metastasis. Here we show that human breast cancer cells organize F-actin rich structures in response to transforming growth factor beta that colocalize with areas of extracellular matrix degradation. We further show that organizing the complex of proteins needed to form these structures requires signaling through phosphatidylinositide 3-kinase and Src kinase, while activating the proteases involved in degradation of extracellular matrix requires extracellular signal-regulated kinase signaling, and that each of these pathways is activated by transforming growth factor beta in CA1D human breast cancer cells.

Generation and characterization of monoclonal antibodies against the proregion of human desmoglein-2.

Abstract Cadherins are synthesized with a signal sequence and a proregion that must be removed for optimal adhesive activity. Mutations that prevent processing of cadherins have been implicated in a number of human diseases; thus understanding their processing is critical. In this study, we produced and characterized a number of monoclonal antibodies against the proregion of the desmosomal cadherin, human desmoglein-2, that will facilitate investigations into the processing of this protein.

Cadherin switching.

The cadherin molecules at adherens junctions have multiple isoforms. Cadherin isoform switching (cadherin switching) occurs during normal developmental processes to allow cell types to segregate from one another. Tumor cells often recapitulate this activity and the result is an aggressive tumor cell that gains the ability to leave the site of the tumor and metastasize. At present, we understand some of the mechanisms that promote cadherin switching and some of the pathways downstream of this process that influence cell behavior. Specific cadherin family members influence growth-factor-receptor signaling and Rho GTPases to promote cell motility and invasion. In addition, p120-catenin probably plays multiple roles in cadherin switching, regulating Rho GTPases and stabilizing cadherins.

Collagen I-mediated up-regulation of N-cadherin requires cooperative signals from integrins and discoidin domain receptor 1.

Tumor cells undergo epithelial-to-mesenchymal transition (EMT) to convert from a benign to a malignant phenotype. Our recent focus has been signaling pathways that promote EMT in response to collagen. We have shown that human pancreatic cancer cells respond to collagen by up-regulating N-cadherin, which promotes tumor growth, invasion, and metastasis. Initial characterization showed that knocking down c-Jun NH2-terminal kinase prevented N-cadherin up-regulation and limited tumor growth and invasion in a mouse model for pancreatic cancer. The current study was designed to understand the pathway from collagen to N-cadherin up-regulation. Initiation of the signal requires two collagen receptors, alpha2beta1 integrin and discoidin domain receptor (DDR) 1. Each receptor propagates signals through separate pathways that converge to up-regulate N-cadherin. Focal adhesion kinase (FAK)-related protein tyrosine kinase (Pyk2) is downstream of DDR1, whereas FAK is downstream of alpha2beta1 integrin. Both receptor complexes rely on the p130 Crk-associated substrate scaffold. Interestingly, Rap1, but not Rho family guanosine triphosphatases, is required for the response to collagen I.

Collagen I promotes epithelial-to-mesenchymal transition in lung cancer cells via transforming growth factor-beta signaling.

Epithelial-to-mesenchymal transition (EMT) is a fundamental biological process whereby epithelial cells lose their polarity and undergo a transition to a mesenchymal phenotype. When cancer cells invade adjacent tissues, they use a mechanism akin to EMT, and understanding the molecular mechanisms that drive this transition will facilitate studies into new targets for prevention of metastasis. Extracellular stimuli, such as growth factors, and their cytosolic effectors cooperate to promote EMT. In highly fibrotic cancers like lung cancer, it is thought that extracellular matrix molecules, including collagen, can initiate signals that promote EMT. Here, we present data showing that collagen I induces EMT in non-small cell lung cancer cell lines, which is prevented by blocking transforming growth factor (TGF)-beta3 signaling. In addition, we show that collagen I-induced EMT is prevented by inhibitors of phosphoinositide 3-kinase and extracellular signal-related kinase signaling, which promotes transcription of TGF-beta3 mRNA in these cells. Thus, our data are consistent with the hypothesis that collagen I induces EMT in lung cancer cells by activating autocrine TGF-beta3 signaling. Epidermal growth factor also seems to initiate EMT via a TGF-dependent mechanism.

The regulatory or phosphorylation domain of p120 catenin controls E-cadherin dynamics at the plasma membrane.

In contrast to growth factor-stimulated tyrosine phosphorylation of p120, its relatively constitutive serine/threonine phosphorylation is not well understood. Here we examined the role of serine/threonine phosphorylation of p120 in cadherin function. Expression of cadherins in cadherin-null cells converted them to an epithelial phenotype, induced p120 phosphorylation and localized it to sites of cell contact. Detergent solubility and immunofluorescence confirmed that phosphorylated p120 was at the plasma membrane. E-cadherin constructs incapable of traveling to the plasma membrane did not induce serine/threonine phosphorylation of p120, nor did cadherins constructs incapable of binding p120. However, an E-cadherin cytoplasmic domain construct artificially targeted to the plasma membrane did induce serine/threonine phosphorylation of p120, suggesting phosphorylation occurs independently of signals from cadherin dimerization and trafficking through the ER/Golgi. Solubility assays following calcium switch showed that p120 isoform 3A was more effective at stabilizing E-cadherin at the plasma membrane relative to isoform 4A. Since the major phosphorylation domain of p120 is included in isoform 3A but not 4A, we tested p120 mutated in the known phosphorylation sites in this domain and found that it was even less effective at stabilizing E-cadherin. These data suggest that serine/threonine phosphorylation of p120 influences the dynamics of E-cadherin in junctions.

ADH-1 suppresses N-cadherin-dependent pancreatic cancer progression.

Pancreatic cancer is one of the most aggressive malignant diseases. We recently reported that N-cadherin plays a key role in tumor progression and metastasis in pancreatic cancer. For this study, we sought to determine if an N-cadherin-blocking peptide (ADH-1) could prevent N-cadherin-mediated tumor progression in a mouse model for pancreatic cancer. The effect of ADH-1 on N-cadherin-mediated cell scattering and migration on collagen I was examined using pancreatic cancer cells. We also examined the influence of ADH-1 on cell apoptosis. Furthermore, in vivo animal studies were performed using orthotopic injection of N-cadherin overexpressing BxPC-3 cells with or without ADH-1 treatment. BxPC-3 and Capan-1 cells exhibited increased expression of N-cadherin in response to collagen I. This increase in N-cadherin promoted cell scattering and migration in response to collagen I. ADH-1 prevented these changes, but did not inhibit upregulation of N-cadherin. TUNEL assays and immunoblots for caspase-3 showed that ADH-1 induced apoptosis in a concentration dependent and N-cadherin dependent manner in pancreatic cancer cells. ADH-1 treatment resulted in significant reductions in tumor growth and lung metastasis in a mouse model for pancreatic cancer. The N-cadherin antagonist, ADH-1 has significant antitumor activity against N-cadherin-expressing cells using in vitro assays and in an orthotopic mouse model for pancreatic cancer, raising the possibility that N-cadherin antagonists have therapeutic potential for the treatment of pancreatic cancer in humans.