ProNodal acts via FGFR3 to govern duration of Shh expression in the prechordal mesoderm.

The secreted glycoprotein sonic hedgehog (Shh) is expressed in the prechordal mesoderm, where it plays a crucial role in induction and patterning of the ventral forebrain. Currently little is known about how Shh is regulated in prechordal tissue. Here we show that in the embryonic chick, Shh is expressed transiently in prechordal mesoderm, and is governed by unprocessed Nodal. Exposure of prechordal mesoderm microcultures to Nodal-conditioned medium, the Nodal inhibitor CerS, or to an ALK4/5/7 inhibitor reveals that Nodal is required to maintain both Shh and Gsc expression, but whereas Gsc is largely maintained through canonical signalling, Nodal signals through a non-canonical route to maintain Shh. Further, Shh expression can be maintained by a recombinant Nodal cleavage mutant, proNodal, but not by purified mature Nodal. A number of lines of evidence suggest that proNodal acts via FGFR3. ProNodal and FGFR3 co-immunoprecipitate and proNodal increases FGFR3 tyrosine phosphorylation. In microcultures, soluble FGFR3 abolishes Shh without affecting Gsc expression. Further, prechordal mesoderm cells in which Fgfr3 expression is reduced by Fgfr3 siRNA fail to bind to proNodal. Finally, targeted electroporation of Fgfr3 siRNA to prechordal mesoderm in vivo results in premature Shh downregulation without affecting Gsc. We report an inverse correlation between proNodal-FGFR3 signalling and pSmad1/5/8, and show that proNodal-FGFR3 signalling antagonises BMP-mediated pSmad1/5/8 signalling, which is poised to downregulate Shh. Our studies suggest that proNodal/FGFR3 signalling governs Shh duration by repressing canonical BMP signalling, and that local BMPs rapidly silence Shh once endogenous Nodal-FGFR3 signalling is downregulated.

Early experience with laparoscopic lavage in acute complicated diverticulitis.

BACKGROUND: Contemporary surgical management of complicated diverticulitis is controversial. Traditionally, the gold standard has been resection and colostomy, but recently peritoneal lavage and drainage without resection in cases of purulent peritonitis have been suggested. This study aims to review our initial experience with laparoscopic peritoneal lavage for complicated diverticulitis. METHODS: Retrospective review of all patients who underwent emergent peritoneal lavage and drainage for acute complicated diverticulitis. RESULTS: Five-hundred-thirty-eight patients admitted for acute diverticulitis between 2007 and 2012 were recorded in the database. Thirty seven underwent emergent surgery of which 10 had peritoneal lavage and drainage without colonic resection for complicated diverticulitis causing peritonitis. Peritoneal lavage and drainage resulted in the resolution of acute symptoms in all cases. In long-term follow-up, 3 (30%) patients required elective resection owing to symptomatic disease, two of these due to recurrent diverticulitis, and one owing to complicated fistula following the procedure. CONCLUSION: Peritoneal lavage is a feasible option for complicated diverticulitis with purulent non-fecal peritonitis, but a significant portion of the patients may require elective resection. Comparative studies with emergent resection are needed to determine the role of peritoneal lavage in complicated diverticulitis.

The Use of Active Coagulation Whole Blood-An Innovative Treatment Strategy for Hard-To-Heal Wounds.

BACKGROUND: Deep and tunneling wounds are a challenge to apply and maintain most advanced wound dressings to promote effective healing. An autologous whole blood clot is a topical treatment and has been found to be safe and effective in healing cutaneous wounds. The active coagulation whole blood (ACWB) clot treatment, using the patient's own blood, is used to treat deep and tunneling wounds, by mixing the blood with coagulation components and applying it into the wound cavity allowing the clot to re-form inside the wound. We aimed to explore ACWB treatment in hard-to-heal wounds. METHODS: 5 patients with multiple comorbidities, exhibiting surgical abdominal wound, chronic pilonidal sinus, stage 4 sacral pressure ulcer with exposed bone, post-amputation surgical site wound, and non-healing wound dehiscence at the site of a prior hip replacement, were all treated with the ACWB clot treatment. RESULTS: Complete wound healing was observed in 4/5 cases. In the fifth case, there was a 70% reduction in the depth and surface area of the abdominal surgical wound. DISCUSSION: The ACWB treatment was found to be effective in deep wounds with cavities and exposed structures. ACWB, in its flowable form, can effectively provide coverage of the deepest interstices of the wound's cavities by virtue of its liquid properties, forming a fibrin matrix, mimicking the role of the extracellular matrix. The flowable formulation of ACWB treatment safely and efficiently provides coverage of the entirety of the wound surface to improve the time and process of complex wound surface healing.

The nodal precursor acting via activin receptors induces mesoderm by maintaining a source of its convertases and BMP4.

During early mouse development, the subtilisin-like proprotein convertases (SPC) Furin and PACE4 pattern the primitive ectoderm and visceral endoderm, presumably by activating the TGFss-related Nodal precursor. Here, mutation of the SPC motif provides direct evidence that Nodal processing is essential to specify anterior visceral endoderm and mesendoderm. Surprisingly, however, the Nodal precursor binds and activates activin receptors to maintain expression of Furin, PACE4, and Bmp4 in extraembryonic ectoderm at a distance from the Nodal source. In return, Bmp4 induces Wnt3, which amplifies Nodal expression in the epiblast and mediates induction of mesoderm. We conclude that uncleaved Nodal sustains the extraembryonic source of proprotein convertases and Bmp4 to amplify Nodal signaling in two nonredundant feedback loops with dual timescales and to localize primitive streak formation at the posterior pole. Based on mathematical modeling, we discuss how these sequential loops control cell fate.

Extraembryonic proteases regulate Nodal signalling during gastrulation.

During gastrulation, a cascade of inductive tissue interactions converts pre-existing polarity in the mammalian embryo into antero-posterior pattern. This process is triggered by Nodal, a protein related to transforming growth factor-beta (TFG-beta) that is expressed in the epiblast and visceral endoderm, and its co-receptor Cripto, which is induced downstream of Nodal. Here we show that the proprotein convertases Spc1 and Spc4 (also known as Furin and Pace4, respectively) are expressed in adjacent extraembryonic ectoderm. They stimulate Nodal maturation after its secretion and are required in vivo for Nodal signalling. Embryo explants deprived of extraembryonic ectoderm phenocopy Spc1(-/-); Spc4(-/-) double mutants in that endogenous Nodal fails to induce Cripto. But recombinant mature Nodal, unlike uncleaved precursor, can efficiently rescue Cripto expression. Cripto is also expressed in explants treated with bone morphogenetic protein 4 (BMP4). This indicates that Nodal may induce Cripto through both a signalling pathway in the embryo and induction of Bmp4 in the extraembryonic ectoderm. A lack of Spc1 and Spc4 affects both pathways because these proteases also stimulate induction of Bmp4.

Long-term results of fibrin glue treatment for cryptogenic perianal fistulas: a multicenter study.

BACKGROUND: Instillation of fibrin glue, a simple and safe procedure, has been shown to have a moderate short-term success rate in the treatment of cryptogenic perianal fistulas. OBJECTIVE: This study aimed to assess the long-term outcome of this procedure. DESIGN: This study included a retrospective chart review and telephone interviews. SETTINGS: This study was conducted at 4 university-affiliated medical centers. PATIENTS: Patients were included who underwent fibrin glue instillation for complex cryptogenic fistula between 2002 and 2003 within a prospective trial and had successful healing. INTERVENTIONS: Fibrin glue was instilled for complex cryptogenic fistula. MAIN OUTCOME MEASURES: The main outcome measure was long-term fistula healing. RESULTS: Sixty patients participated in the initial trial; the fistulas in 32 of these patients were healed at 6 months. We have located and interviewed 23 (72%) of those patients. Seventeen (74%) patients remained disease free at a mean follow-up of 6.5 years. Six (26%) patients had variable degrees of recurrence; 4 needed further surgical intervention and 2 were treated with antibiotics only. Recurrent disease occurred at an average of 4.1 years (range, 11 mo to 6 y) from surgery, and on several occasions was at a different location in the perianal region. None of the patients experienced incontinence following the procedure. LIMITATIONS: The retrospective nature of this long-term follow-up was a limitation. Twenty-eight percent of the potentially eligible patients were lost to long-term follow-up. CONCLUSIONS: Short-term success of fibrin glue in the treatment of cryptogenic perianal fistula is predictive of long-term healing, but a quarter of those healed in the short term may develop recurrent symptoms in the long run. Injection of fibrin glue remains a safe and simple procedure and may preclude extensive surgery.

Nodal stability determines signaling range.

Secreted TGFbeta proteins of the Nodal family pattern the vertebrate body axes and induce mesoderm and endoderm . Nodal proteins can act as morphogens , but the mechanisms regulating their activity and signaling range are poorly understood. In particular, it has been unclear how inefficient processing or rapid turnover of the Nodal protein influences autocrine and paracrine signaling properties . Here, we evaluate the role of Nodal processing and stability in tissue culture and zebrafish embryos. Removal of the pro domain potentiates autocrine signaling but reduces Nodal stability and signaling range. Insertion of an N-glycosylation site present in several related TGFbeta proteins increases the stability of mature Nodal. The stabilized form of Nodal acts at a longer range than the wild-type form. These results suggest that increased proteolytic maturation of Nodal potentiates autocrine signaling, whereas increased Nodal stability extends paracrine signaling.

The Clinical Utility of Over-the-Scope Clip for the Treatment of Gastrointestinal Defects.

BACKGROUND: The over-the-scope clip (OTSC) is a novel endoscopic tool that enables non-surgical management of gastrointestinal (GI) defects. The aim of this study was to report our experience with OTSC for patients with GI defects. METHODS: A prospectively maintained IRB-approved institutional database was queried for all patients treated with OTSC from 2012 to 2015. Primary outcome was the clinical success of the OTSC for the individual indication. Secondary outcome was the number of additional procedures needed following OTSC. RESULTS: Fifty-one patients were treated with OTSC: upper GI (UGI) 30 and lower GI (LGI) 21. GI leak (n = 24; UGI = 12, LGI = 12) and fistulae (n = 17; UGI = 8, LGI = 9) were the most common indications. Overall success rate for the treatment of leaks was 59 % [UGI 66 % vs. LGI 33 % (p = 0.1)]. A lower success rate (35 %) was noted for fistulae [UGI 62 % vs. LGI 0 % (p = 0.001)]. Success rates for UGI perforation, bleeding, and stent anchoring indications were 75, 75, and 50 %, respectively. Additional endoscopic or surgical interventions following OTSC were indicated in 68.6 % of the patients. CONCLUSIONS: OTSC appears to have additional value in treating UGI defects. However, lower success rates for LGI defects were noted, specifically for fistulae. Most patients require an additional endoscopic or surgical procedure after one OTSC application.

Innovative integrative bedside teaching model improves tutors' self-assessments of teaching skills and attitudes.

INTRODUCTION: Patient bedside is the ideal setting for teaching physical examination, medical interviewing, and interpersonal skills. Herein we describe a novel model for bedside teaching (BST) practiced during tutor training workshop and its resulting effect on practitioners' self assessment of teaching skills and perceptions. METHODS: One-day tutor training workshop included theoretical knowledge supplementation regarding tutors' roles as well as implementing practical tools for clinical education, mainly BST model. The model, which emphasizes simultaneous clinical and communication teaching in a stepwise approach, was practiced by consecutive simulations with a gradual escalation of difficulty and adjusted instruction approaches. Pre- and post-workshop-adjusted questionnaires using a Likert scale of 1 to 4 were completed by participants and compared. RESULTS: Analysis was based on 25 out of 48 participants who completed both questionnaires. Significantly improved teaching skills were demonstrated upon workshop completion (mean 3.3, SD 0.5) compared with pre-training (mean 2.6, SD 0.6; p<0.001) with significant increase in most examined parameters. Significantly improved tutor's roles internalization was demonstrated after training completion (mean 3.7, SD 0.3) compared with pre-workshop (mean 3.5 SD 0.5; p=0.002). DISCUSSION: Successful BST involves combination of clinical and communication skills. BST model practiced during the workshop may contribute to improved teaching skills in this challenging environment.

Cell-specific integration of artificial organelles based on functionalized polymer vesicles.

Cell organelles are subcellular structures characterized by specific functionalities. They often consist of membrane-delineated microcompartments with a unique set of enzymes. Here we report the design of synthetic organelles based on nanometer-sized polymer vesicles, show their introduction into cells in a target-specific fashion, document their intact biochemical functionality in the cellular environment, and study their intracellular trafficking. This novel paradigm of introducing polymer-based artificial organelles to specific target cells for expansion of their biochemical capabilities appears suited for biomedical applications such as enzyme replacement in genetic diseases or, more generically, to add a desired biochemical function to a cell.

Inhibition of macrophage phagocytotic activity by a receptor-targeted polymer vesicle-based drug delivery formulation of pravastatin.

Ruptures of macrophage-rich atherosclerotic plaques in the coronary arteries are the main reason for heart attack. Targeted therapeutic interventions with an inhibitory effect on the macrophages promise to be beneficial, but currently available drugs such as statins achieve event reductions of only 30%. Dose-limiting adverse effects in remote organs prohibit achieving higher drug levels known to have strong inhibitory effects on macrophages. Receptor-specific targeting using statin-loaded nanometer-sized triblock copolymer vesicles with targeting moieties might allow high-dose treatment for improved efficacy, while minimizing toxicity in other cells. Vesicle uptake by target cells but not other cell types and slow intracellular content release was observed. A major improvement in biologic efficacy was observed for polymer vesicles compared to free drug, whereas no increased cytotoxicity was observed in muscle cells. Such high-dose, targeted therapy of statins through cell-specific polymer vesicles allows novel treatment paradigms not only for atherosclerosis, but appears promising for a wide range of drugs and diseases.

Toward intelligent nanosize bioreactors: a pH-switchable, channel-equipped, functional polymer nanocontainer.

To develop an intelligent sensor-effector functionality on the nanoscale, a pH-switchable, controlled nanoreactor based on amphiphilic copolymer membranes was built. The nanovesicles were equipped with bacterial transmembrane ompF pore proteins and the pH-sensitive enzyme acid phosphatase, resulting in a switchable substrate processing at pH 4-6.5. Ideal pH and substrate concentrations for the reaction were determined experimentally. In future, the reactor might be used for self-regulating targeted diagnostic and therapeutic applications in medicine.

Nodal protein processing and fibroblast growth factor 4 synergize to maintain a trophoblast stem cell microenvironment.

Before implantation in the uterus, mammalian embryos set aside trophoblast stem cells that are maintained in the extraembryonic ectoderm (ExE) during gastrulation to generate the fetal portion of the placenta. Their proliferation depends on diffusible signals from neighboring cells in the epiblast, including fibroblast growth factor 4 (Fgf4). Here, we show that Fgf4 expression is induced by the transforming growth factor beta-related protein Nodal. Together with Fgf4, Nodal also acts directly on neighboring ExE to sustain a microenvironment that inhibits precocious differentiation of trophoblast stem cells. Because the ExE itself produces the proteases Furin and PACE4 to activate Nodal, it represents the first example, to our knowledge, of a stem cell compartment that actively maintains its own microenvironment.

Rescue of MODY-1 by agonist ligands of hepatocyte nuclear factor-4alpha.

Missense mutations of the ligand binding domain of hepatocyte nuclear factor (HNF)-4alpha result in maturity onset diabetes of the young (MODY)-1. We show here that MODY-1 as well as Gln-185 missense mutants of the ligand binding domain of HNF-4alpha fail to transactivate transcription of HNF-4alpha-responsive genes. Defective transactivation by these mutants is accounted for by their reduced binding affinities for fatty acyl agonist ligands of HNF-4alpha. These mutants may be rescued by exogenous fatty acid agonist ligands of HNF-4alpha, yielding transcriptional activities in the wild type range. The effect of added ligands is synergistic with that of transcriptional coactivators of HNF-4alpha. These findings may indicate the means for treating selected MODY-1 subjects with HNF-4alpha agonist nutrients and drugs.