Epithelial cells polarize and orient polarity in response to cell-cell and cell-matrix adhesion. Although there has been much recent progress in understanding the general polarizing machinery of epithelia, it is largely unclear how this machinery is controlled by the extracellular environment. To explore the signals from cell-matrix interactions that control orientation of cell polarity, we have used three-dimensional culture systems in which Madin-Darby canine kidney (MDCK) cells form polarized, lumen-containing structures. We show that interaction of collagen I with apical ␤1-integrins after collagen overlay of a polarized MDCK monolayer induces activation of Rac1, which is required for collagen overlay-induced tubulocyst formation. Cysts, comprised of a monolayer enclosing a central lumen, form after embedding single cells in collagen. In those cultures, addition of a ␤1-integrin function-blocking antibody to the collagen matrix gives rise to cysts that have defects in the organization of laminin into the basement membrane and have inverted polarity. Normal polarity is restored by either expression of activated Rac1, or the inclusion of excess laminin-1 (LN-1). Together, our results suggest a signaling pathway in which the activation of ␤1-integrins orients the apical pole of polarized cysts via a mechanism that requires Rac1 activation and laminin organization into the basement membrane. INTRODUCTIONPolarization of cells is a fundamental process in biology. Epithelial cells polarize into apical and basolateral poles. Much has been learned recently about the mechanisms of epithelial polarization. Three major polarization complexes, the Par3/Par6/atypical protein kinase C (aPKC), Crumbs/ PATJ/Stardust, and Scribble/Discs Large/Lethal Giant Larvae complexes are conserved from Caenorhabditis elegans and Drosophila to mammals and are essential for epithelial polarization (Roh and Margolis, 2003;Macara, 2004). Cell polarization also requires interactions of the cells with each other and the extracellular matrix (ECM), as well as polarized organization of the cytoskeleton and membrane traffic, although how these processes are connected to the three polarization complexes is largely obscure (Vega-Salas et al., 1987;Yeaman et al., 1999;O'Brien et al., 2002;Mostov et al., 2003;Nelson, 2003;Zegers et al., 2003).Formation of epithelial tissues requires that the orientation of polarity of individual epithelial cells be coordinated in space and time. This was underappreciated in studies using cells grown on filter supports, because the filter provides an overriding extrinsic cue to orient the cells with the basolateral surface facing the filter and the apical surface opposite. Building on earlier observations (Wang et al., 1990a), we found that generation of epithelial polarity can be uncoupled from the orientation of that polarity (O'Brien et al., 2001). Madin-Darby canine kidney (MDCK) epithelial cells grown in three-dimensional (3D) collagen gels form cysts, where the apical surface of a polarized monolayer of cells fa...

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OBJECTIVES Median arcuate ligament syndrome (MALS) is a vascular compression syndrome with symptoms that overlap chronic functional abdominal pain (CFAP). We report our experience treating MALS in a pediatric cohort previously diagnosed with CFAP. PATIENTS AND METHODS We prospectively evaluated 46 pediatric (<21 years of age) patients diagnosed with MALS at a tertiary care referral center from 2008 to 2012. All patients had previously been diagnosed with CFAP. Patients were evaluated for celiac artery compression by duplex ultrasound and diagnosis was confirmed by computed tomography. Quality of life (QOL) was determined by pre- and post-surgical administration of PedsQLtm questionnaire. The patients underwent laparoscopic release of the median arcuate ligament overlying the celiac artery which included surgical neurolysis. We examined the hemodynamic changes in parameters of the celiac artery and peri-operative QOL outcomes to determine correlation. RESULTS All patients had studies suggestive of MALS on duplex and computed tomography. 91% (n=42) positive for MALS were females. All patients underwent a technically satisfactory laparoscopic surgical release resulting in a significant improvement in blood flow through the celiac artery. There were no deaths and a total of 9 complications, 8 requiring a secondary procedure. 33 patients were administered QOL surveys. 18 patients completed the survey with 15 (83%) patients reporting overall improvement in the QOL. Overall, 31/46 patients (67%) reported improvement of symptoms since the time of surgery. CONCLUSIONS MALS was found to be more common in pediatric females than males. Laparoscopic release of the celiac artery can be performed safely in the pediatric population. Surgical release of the artery and resultant neurolysis resulted in significant improvement in the blood flow, symptoms, and overall QOL in this cohort. The overall improvement in QOL outcome measures after surgery leads us to conclude that MALS might be earlier diagnosed and possibly treated in patients with CFAP. We recommend a multidisciplinary team approach to care for these complex patients.

for the Midwest Pediatric Surgery Consortium IMPORTANCE Nonoperative management with antibiotics alone has the potential to treat uncomplicated pediatric appendicitis with fewer disability days than surgery.OBJECTIVE To determine the success rate of nonoperative management and compare differences in treatment-related disability, satisfaction, health-related quality of life, and complications between nonoperative management and surgery in children with uncomplicated appendicitis. DESIGN, SETTING, AND PARTICIPANTS Multi-institutional nonrandomized controlled intervention study of 1068 children aged 7 through 17 years with uncomplicated appendicitis treated at 10 tertiary children's hospitals across 7 US states between May 2015 and October 2018 with 1-year follow-up through October 2019. Of the 1209 eligible patients approached, 1068 enrolled in the study. INTERVENTIONS Patient and family selection of nonoperative management with antibiotics alone (nonoperative group, n = 370) or urgent (Յ12 hours of admission) laparoscopic appendectomy (surgery group, n = 698). MAIN OUTCOMES AND MEASURESThe 2 primary outcomes assessed at 1 year were disability days, defined as the total number of days the child was not able to participate in all of his/her normal activities secondary to appendicitis-related care (expected difference, 5 days), and success rate of nonoperative management, defined as the proportion of patients initially managed nonoperatively who did not undergo appendectomy by 1 year (lowest acceptable success rate, Ն70%). Inverse probability of treatment weighting (IPTW) was used to adjust for differences between treatment groups for all outcome assessments. RESULTS Among 1068 patients who were enrolled (median age, 12.4 years; 38% girls), 370 (35%) chose nonoperative management and 698 (65%) chose surgery. A total of 806 (75%) had complete follow-up: 284 (77%) in the nonoperative group; 522 (75%) in the surgery group. Patients in the nonoperative group were more often younger (median age, 12.3 years vs 12.5 years), Black (9.6% vs 4.9%) or other race (14.6% vs 8.7%), had caregivers with a bachelor's degree (29.8% vs 23.5%), and underwent diagnostic ultrasound (79.7% vs 74.5%). After IPTW, the success rate of nonoperative management at 1 year was 67.1% (96% CI, 61.5%-72.31%; P = .86). Nonoperative management was associated with significantly fewer patient disability days at 1 year than did surgery (adjusted mean, 6.6 vs 10.9 days; mean difference, −4.3 days (99% CI, −6.17 to −2.43; P < .001). Of 16 other prespecified secondary end points, 10 showed no significant difference.CONCLUSION AND RELEVANCE Among children with uncomplicated appendicitis, an initial nonoperative management strategy with antibiotics alone had a success rate of 67.1% and, compared with urgent surgery, was associated with statistically significantly fewer disability days at 1 year. However, there was substantial loss to follow-up, the comparison with the prespecified threshold for an acceptable success rate of nonoperative management was not stat...

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